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3,335 results on '"Kraus, M"'

1. Two-Loop Master Integrals for Leading-Color $pp\to t\bar{t}H$ Amplitudes with a Light-Quark Loop

Author: Cordero, F. Febres, Figueiredo, G., Kraus, M., Page, B., and Reina, L.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Theory
Abstract: We compute the two-loop master integrals for leading-color QCD scattering amplitudes including a closed light-quark loop in $t\bar{t}H$ production at hadron colliders. Exploiting numerical evaluations in modular arithmetic, we construct a basis of master integrals satisfying a system of differential equations in $\epsilon$-factorized form. We present the analytic form of the differential equations in terms of a minimal set of differential one-forms. We explore properties of the function space of analytic solutions to the differential equations in terms of iterative integrals which can be exploited for studying the analytic form of related scattering amplitudes. Finally, we solve the differential equations using generalized series expansions to numerically evaluate the master integrals in physical phase space. As the first computation of a set of two-loop seven-scale master integrals, our results provide valuable input for analytic studies of scattering amplitudes in processes involving massive particles and a large number of kinematic scales., Comment: published version, fixed typo in ancillary files
Published: 2023
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2. BCD spectrophotometry for massive stars in transition phases

Author: Aidelman, Y. J., Fernandes, M. Borges, Cidale, L. S., Castelli, A. Smith, Arias, M. L., Zorec, J., Kraus, M., Torres, A., Souza, T. B., and Cochetti, Y. R.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: Context. Stars in transition phases, like those showing the B[e] phenomenon and luminous blue variables (LBVs), undergo strong, often irregular mass ejection events. The prediction of these phases in stellar evolution models is therefore extremely difficult if not impossible. As a result, their effective temperatures, their luminosities and even their true nature are not fully known. Aims. A suitable procedure to derive the stellar parameters of these types of objects is to use the BCD spectrophotometric classification system, based on the analysis of the Balmer discontinuity. The BCD parameters ({\lambda}_1, D) are independent of interstellar extinction and circumstellar contributions. Methods. We obtained low-resolution spectra for 14 stars with the B[e] phenomenon and LBVs. Using the BCD method, we derived the stellar and physical parameters. The study was complemented with the information provided by the JHK colour-colour diagram. Results. For each star, the BCD system gives a complete set of fundamental parameters and related quantities such as luminosity and distance. We confirmed HK Ori, HD 323771 and HD 52721 as pre-main sequence HAe/B[e], AS 202 and HD 85567 as FS CMa-type, and HD 62623 as sgB[e] stars. We classified Hen 3-847, CD-24 5721, and HD 53367 as young B[e] stars or FS CMa-type candidates, and HD 58647 as a slightly evolved B[e] star. In addition, Hen 3-1398 is an sgB[e] and MWC 877, CPD-59 2854 and LHA 120-S 65 are LBV candidates. The stellar parameters of the latter two LBVs are determined for the first time. Conclusions. Our results emphasise that the BCD system is a highly valuable tool to derive stellar parameters and physical properties of B-type stars in transition phases. This method can be combined with near-IR colour-colour diagrams to determine or confirm the evolutionary stage of emission-line stars with dust disks.
Published: 2023
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3. Two-loop master integrals for leading-color pp→tt¯H amplitudes with a light-quark loop

Author: Cordero, F. Febres, Figueiredo, G., Kraus, M., Page, B., and Reina, L.
Published: 2024
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4. V838 Mon: A slow waking up of Sleeping Beauty?

Author: Liimets, T., Kolka, I., Kraus, M., Eenmäe, T., Tuvikene, T., Augusteijn, T., Amaral, L. Antunes, Djupvik, A. A., Telting, J. H., Deshev, B., Kankare, E., Kankare, J., Lindberg, J. E., Amby, T. M., Pursimo, T., Somero, A., Thygesen, A., and Strøm, P. A.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: Context. V838 Monocerotis is a peculiar binary that underwent an immense stellar explosion in 2002, leaving behind an expanding cool supergiant and a hot B3V companion. Five years after the outburst, the B3V companion disappeared from view, and so far did not recover. Aims. We investigate the changes in the light curve and spectral features Methods. A monitoring campaign has been performed during the past 13 years with the Nordic Optical Telescope to obtain optical photometric and spectroscopic data. The data sets are used to analyse the temporal evolution of the spectral features and the spectral energy distribution, and to characterize the object. Results. Our photometric data show a steady brightening in all bands during the past 13 years, which is particularly prominent in the blue. This rise is also reflected in the spectra, showing a gradual relative increase in the continuum flux at shorter wavelengths. In addition, a slow brightening of the Ha emission line starting in 2015 was detected. These changes might imply that the B3V companion is slowly reappearing. During the same time interval, our analysis reveals a considerable change in the observed colours of the object along with a steady decrease in the strength and width of molecular absorption bands in our low-resolution spectra. These changes suggest a rising temperature of the cool supergiant along with a weakening of its wind, most likely combined with a slow recovery of the secondary due to the evaporation of the dust and accretion of the material from the shell in which the hot companion is embedded. From our medium-resolution spectra, we find that the heliocentric radial velocity of the atomic absorption line of TiI 6556.06 A has been stable for more than a decade. We propose that TiI lines are tracing the velocity of the red supergiant in V838 Mon, and not representing the infalling matter as previously stated., Comment: 13 pages, 12 figures, accepted for publication in A&A
Published: 2022
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5. Follow-Up of Extended Shells around B[e] Stars

Author: Liimets, T., Kraus, M., Moiseev, A., Duronea, N., Cidale, L. S., and Farina, Cecilia
Subjects: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies
Abstract: B[e] stars are massive B type emission line stars in different evolutionary stages ranging from pre-main sequence to post-main sequence. Due to their mass loss and ejection events these objects deposit huge amounts of mass and energy into their environment and enrich it with chemically processed material, contributing significantly to the chemical and dynamical evolution of their host galaxies. However, the large-scale environments of these enigmatic objects have not attracted much attention. The first and so far only catalog reporting the detection of extended shells around a sample of B[e] stars was an Ha imaging survey carried out in the year 2001, and was limited to bright targets in the northern hemisphere. We have recently started a follow-up of those targets to detect possible evolution of their nebulae in the plane of the sky over a baseline of two decades. Furthermore, we extend our survey to southern targets and fainter northern ones to complement and complete our knowledge on large-scale ejecta surrounding B[e] stars. Besides imaging in Ha and selected nebular lines, we utilize long-slit and 3D spectral observations across the nebulae to derive their physical properties. We discovered pronounced nebula structures around 15 more objects, resulting in a total of 27 B[e] stars with a large-scale nebula. Here we present our (preliminary) results for three selected objects: the two massive supergiants MWC137 and MWC 314, and the unclassified B[e] star MWC 819., Comment: 11 pages, 5 figures, Published in Galaxies
Published: 2022
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6. Equal waiting times for all? Empirical evidence for elective surgeries in the Austrian public healthcare system

Author: Kraus, M., Stacherl, B., Czypionka, T., and Mayer, S.
Published: 2024
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7. Modeling uncertainties of $t\bar{t}W^\pm$ multilepton signatures

Author: Bevilacqua, G., Bi, H. Y., Cordero, F. Febres, Hartanto, H. B., Kraus, M., Nasufi, J., Reina, L., and Worek, M.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract: In light of recent discrepancies between the modeling of $t\bar{t} W^\pm$ signatures and measurements reported by the Large Hadron Collider (LHC) experimental collaborations, we investigate in detail theoretical uncertainties for multi-lepton signatures. We compare results from the state-of-the-art full off-shell calculation and its Narrow Width Approximation to results obtained from the on-shell $t\bar{t} W^\pm$ calculation, with approximate spin-correlations in top-quark and $W$ decays, matched to parton showers. In the former case double-, single-, and non-resonant contributions together with interference effects are taken into account, while the latter two cases are only based on the double resonant top-quark contributions. The comparison is performed for the LHC at $\sqrt{s} = 13$ TeV for which we study separately the multi-lepton signatures as predicted from the dominant NLO contributions at the perturbative orders $\mathcal{O}(\alpha_s^3\alpha^6)$ and $\mathcal{O}(\alpha_s\alpha^8)$. Furthermore, we combine both contributions and propose a simple way to approximately incorporate the full off-shell effects in the NLO computation of on-shell $pp\to t\bar{t} W^\pm$ matched to parton showers., Comment: 37 pages, 10 figures, 1 table, published version
Published: 2021
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8. Rare HCV subtypes and retreatment outcomes in a cohort of European DAA-experienced patients

Author: Antoni, C., Teufel, A., Vogelmann, R., Ebert, M., Balavoine, J., Giostra, E., Berning, M., Hampe, J., Boettler, T., Neumann-Haefelin, C., Thimme, R., De Gottardi, A., Rauch, A., Semmo, N., Ellenrieder, V., Gress, M., Herrmann, A., Stallmach, A., Hoffmann, D., Protzer, U., Kodal, A., Löbermann, M., Götze, T., Keitel-Anselmino, V., Lange, C.M., Zachoval, R., Mayerle, J., Maieron, A., Michl, P., Merle, U., Moradpour, D., Chave, J.-P., Muche, M., Epple, H.-J., Müller-Schilling, M., Kocheise, F., Müller, T., Tacke, F., Roeb, E., Rissland, J., Krawczyk, M., Schulze, P., Semela, D., Spengler, U., Rockstroh, J., Strassburg, C.P., Siebler, J., Schulze zur Wiesch, J., Piecha, F., von Felden, J., Jordan, S., Lohse, A., Sprinzl, M., Galle, P., Stauber, R., Strey, B., Steckstor, W., Schmiegel, W., Brockmeyer, N.H., Canbay, A., Trautwein, C., Uschner, F., Trebicka, J., Weber, T., Wedemeyer, H., Cornberg, M., Manns, M., Wietzke-Braun, P., Günther, R., Willuweit, K., Hilgard, G., Schmidt, H., Zizer, E., Backhus, J., Seufferlein, T., Al-Taie, O., Angeli, W., Beckebaum, S., Erhardt, A., Garrido-Lüneburg, A., Gattringer, H., Genné, D., Gschwantler, M., Gundling, F., Hametner, S., Schöfl, R., Haag, S., Heinzow, H., Heyer, T., Hirschi, C., Jussios, A., Kanzler, S., Kordecki, N., Kraus, M., Kullig, U., Wollschläger, S., Magenta, L., Beretta-Piccoli, B. Terziroli, Menges, M., Mohr, L., Muehlenberg, K., Niederau, C., Paulweber, B., Petrides, A., Pinkernell, M., Piso, R., Rambach, W., Reinhardt, L., Reiser, M., Riecken, B., Rieke, A., Roth, J., Schelling, M., Schlee, P., Schneider, A., Scholz, D., Schott, E., Schuchmann, M., Schulten-Baumer, U., Seelhoff, A., Stich, A., Stickel, F., Ungemach, J., Walter, E., Weber, A., Wege, H., Winzer, T., Abels, W., Adler, M., Audebert, F., Baermann, C., Bästlein, E., Barth, R., Barthel, K., Becker, W., Behrends, J., Benninger, J., Berger, F., Berzow, D., Beyer, T., Bierbaum, M., Blaukat, O., Bodtländer, A., Böhm, G., Börner, N., Bohr, U., Bokemeyer, B., Bruch, H.R., Bucholz, D., Buggisch, P., Matschenz, K., Petersen, J., Burkhard, O., Busch, N., Chirca, C., Delker, R., Diedrich, J., Frank, M., Diehl, M., Tal, A.O., Schneider, M., Dienethal, A., Dietel, P., Dikopoulos, N., Dreck, M., Dreher, F., Drude, L., Ende, K., Ehrle, U., Baumgartl, K., Emke, F., Glosemeyer, R., Felten, G., Hüppe, D., Fischer, J., Fischer, U., Frederking, D., Frick, B., Friese, G., Gantke, B., Geyer, P., Schwind, H.R., Glas, M., Glaunsinger, T., Goebel, F., Göbel, U., Görlitz, B., Graf, R., Gruber, H., Hartmann, C., Klag, C., Härter, G., Herder, M., Heuchel, T., Heuer, S., Hinrichsen, H., Seegers, B., Höffl, K.-H., Hörster, H., Sonne, J.-U., Hofmann, W.P., Holst, F., Hunstiger, M., Hurst, A., Jägel-Guedes, E., John, C., Jung, M., Kallinowski, B., Kapzan, B., Kerzel, W., Khaykin, P., Klarhof, M., Klüppelberg, U., Wolfratshausen, Klugewitz, K., Knapp, B., Knevels, U., Kochsiek, T., Körfer, A., Köster, A., Kuhn, M., Langekamp, A., Künzig, B., Link, R., Littman, M., Löhr, H., Lutz, T., Gute, P., Knecht, G., Lutz, U., Mainz, D., Mahle, I., Maurer, P., Mauss, S., Mayer, C., Möller, H., Heyne, R., Moritzen, D., Mroß, M., Mundlos, M., Naumann, U., Nehls, O., K, Ningel, R., Oelmann, A., Olejnik, H., Gadow, K., Pascher, E., Philipp, A., Pichler, M., Polzien, F., Raddant, R., Riedel, M., Rietzler, S., Rössle, M., Rufle, W., Rump, A., Schewe, C., Hoffmann, C., Schleehauf, D., Schmidt, W., Schmidt-Heinevetter, G., Fabris, J. Schmidtler-von, Schneider, L., Schober, A., Niehaus-Hahn, S., Schwenzer, J., Seidel, T., Seitel, G., Sick, C., Simon, K., Stähler, D., Stenschke, F., Steffens, H., Stein, K., Steinmüller, M., Sternfeld, T., Svensson, K., Tacke, W., Teuber, G., Teubner, K., Thieringer, J., Tomesch, A., Trappe, U., Ullrich, J., Urban, G., Usadel, S., von Lucadou, A., Weinberger, F., Werheid-Dobers, M., Werner, P., Winter, T., Zehnter, E., Zipf, A., Dietz, Julia, Graf, Christiana, Berg, Christoph P., Port, Kerstin, Deterding, Katja, Buggisch, Peter, Peiffer, Kai-Henrik, Vermehren, Johannes, Dultz, Georg, Geier, Andreas, Reiter, Florian P., Bruns, Tony, Schattenberg, Jörn M., Durmashkina, Elena, Gustot, Thierry, Moreno, Christophe, Trauth, Janina, Discher, Thomas, Fischer, Janett, Berg, Thomas, Kremer, Andreas E., Müllhaupt, Beat, Zeuzem, Stefan, and Sarrazin, Christoph
Published: 2024
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9. The Design, Construction, and Commissioning of the KATRIN Experiment

Author: Aker, M., Altenmüller, K., Amsbaugh, J. F., Arenz, M., Babutzka, M., Bast, J., Bauer, S., Bechtler, H., Beck, M., Beglarian, A., Behrens, J., Bender, B., Berendes, R., Berlev, A., Besserer, U., Bettin, C., Bieringer, B., Blaum, K., Block, F., Bobien, S., Bohn, J., Bokeloh, K., Bolz, H., Bornschein, B., Bornschein, L., Böttcher, M., Bouquet, H., Boyd, N. M., Brunst, T., Burritt, T. H., Caldwell, T. S., Chaoui, Z., Chilingaryan, S., Choi, W., Corona, T. J., Cox, G. A., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Dunmore, J. A., Dyba, S., Edzards, F., Eichelhardt, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Felden, A., Fischer, S., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Frenzel, H., Friedel, F., Fulst, A., Gauda, K., Gehring, R., Gil, W., Glück, F., Görhardt, S., Grimm, J., Grohmann, S., Groh, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Häßler, D., Hannen, V., Harms, F., Harper, G. C., Hartmann, J., Haußmann, N., Heizmann, F., Helbing, K., Held, M., Hickford, S., Hilk, D., Hillen, B., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Holzmann, S., Horn, S., Hötzel, M., Houdy, T., Howe, M. A., Huber, A., James, T., Jansen, A., Kaiser, M., Karl, C., Kazachenko, O., Kellerer, J., Kippenbrock, L., Kleesiek, M., Kleifges, M., Kleinfeller, J., Klein, M., Köllenberger, L., Kopmann, A., Korzeczek, M., Kosmider, A., Kovalík, A., Krasch, B., Krause, H., Kraus, M., Kuckert, L., Kumb, A., Kunka, N., Lasserre, T., La Cascio, L., Lebeda, O., Leber, M. L., Lehnert, B., Leiber, B., Letnev, J., Lewis, R. J., Le, T. L., Lichter, S., Lokhov, A., Poyato, J. M. Lopez, Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Mehret, K., Meloni, M., Melzer, C., Menshikov, A., Mertens, S., Minter, L. I., Monreal, B., Mostafa, J., Müller, K., Myers, A. W., Naumann, U., Neumann, H., Niemes, S., Oelpmann, P., Off, A., Ortjohann, H. -W., Osipowicz, A., Ostrick, B., Parno, D. S., Peterson, D. A., Plischke, P., Poon, A. W. P., Prall, M., Priester, F., Ranitzsch, P. C. -O., Reich, J., Renschler, P., Rest, O., Rinderspacher, R., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Rohr, P., Röllig, M., Röttele, C., Rupp, S., Ryšavý, M., Sack, R., Saenz, A., Sagawe, M., Schäfer, P., Schaller, A., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schneidewind, S., Schön, H., Schönung, K., Schrank, M., Schulz, B., Schwarz, J., Šefčík, M., Seitz-Moskaliuk, H., Seller, W., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Sturm, M., Sun, M., Tcherniakhovski, D., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., VanDevender, B. A., Van Wechel, T. D., Vénos, D., Verbeek, A., Vianden, R., Hernández, A. P. Vizcaya, Vogt, K., Wall, B. L., Wandkowsky, N., Weber, M., Weingardt, H., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wierman, K. J., Wilkerson, J. F., Wolf, J., Wüstling, S., Xu, W., Yen, Y. -R., Zacher, M., Zadoroghny, S., Zboril, M., and Zeller, G.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract: The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [https://publikationen.bibliothek.kit.edu/270060419] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [arXiv:1909.06048]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns., Comment: Added missing acknowledgement, corrected performance statement in chapter 4.2.5, updated author list and references
Published: 2021
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10. Intriguing detection of $^{12}$CO molecular emission in a classical Be star

Author: Cochetti, Y. R., Arias, M. L., Kraus, M., Cidale, L. S., Torres, A. F., Granada, A., and Maryeva, O. V.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: In the group of B stars with spectroscopic peculiarities, we can find the Be and the B[e] stars. The Be stars are early-type rapid rotators that present, as their principal characteristic, emission lines of hydrogen and singly ionized metals due to the presence of a gaseous envelope. The B[e] stars present in their spectra heterogeneous features that reveal the presence of regions with very different properties in a gaseous and dusty envelope. Our goal is to study the evolution of the disks around peculiar B stars through the variability of their physical properties and dynamical structure, as well as to set constraints on different models and disk forming mechanisms. Throughout the last decade, we have carried out temporal monitoring of a sample of objects in the near infrared using spectroscopic facilities at the Gemini and Las Campanas Observatories. In the present work, we focus on the classical Be star 12 Vul, for which also optical spectra have been collected quasi-simultaneously. We observed variability in the hydrogen line profiles of 12 Vul, attributed to dissipating and building-up processes of the circumstellar envelope. Also, we found that this Be star presented the $^{12}$CO band heads in emission in one observation. The emission of this molecule has not been previously reported in a Be star, while it is a common feature among B[e] stars. We obtained parameters to describe the $^{12}$CO emitting region and propose different scenarios to explain this intriguing emission., Comment: 6 pages, 3 figures. Accepted for publication in A&A
Published: 2021
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11. Top-quark pair production in association with a $W^\pm$ gauge boson in the POWHEG-BOX

Author: Cordero, F. Febres, Kraus, M., and Reina, L.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract: We present a new Monte Carlo event generator for the production of a top-quark pair in association with a $W^\pm$ boson at hadron colliders in the POWHEG-BOX framework. We consider the next-to-leading-order QCD corrections to the $pp\to t\bar{t} W^\pm$ cross section, corresponding to the $\mathcal{O}(\alpha_s^3\alpha)$ and $\mathcal{O}(\alpha_s\alpha^3)$ terms in the perturbative expansion of the parton-level cross section, and model the decays of $W$ and top quarks at leading order retaining spin correlations. The fixed-order QCD calculation is further interfaced with the Pythia8 parton-shower event generator via the POWHEG method as implemented in the POWHEG-BOX. The corresponding code is now part of the public repository of the POWHEG-BOX. We perform a comparison of different event generators for both the case of inclusive production and the case of the two same-sign leptons signature at the Large Hadron Collider operating at a center-of-mass energy of $13$ TeV. We investigate theoretical uncertainties in the modelling of the fiducial volume stemming from missing higher-order corrections, the different parton shower matching schemes, and the modelling of decays. We find that the subleading contribution at $\mathcal{O}(\alpha_s\alpha^3)$ is particularly sensitive to differences in the matching scheme and higher-order parton shower effects. We observe that in particular jet observables can differ quite visibly although these differences play only a subordinate role in the description of physical observables once all contributions are combined., Comment: 52 pages and 36 beautiful plots, matches published version
Published: 2021
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12. Radiation Protection and C-Arm Operation

Author: Schütz, U., Kraus, M., and Jerosch, Jörg, editor
Published: 2023
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13. Caravel: A C++ Framework for the Computation of Multi-Loop Amplitudes with Numerical Unitarity

Author: Abreu, S., Dormans, J., Cordero, F. Febres, Ita, H., Kraus, M., Page, B., Pascual, E., Ruf, M. S., and Sotnikov, V.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Theory
Abstract: We present the first public version of Caravel, a C++17 framework for the computation of multi-loop scattering amplitudes in quantum field theory, based on the numerical unitarity method. Caravel is composed of modules for the $D$-dimensional decomposition of integrands of scattering amplitudes into master and surface terms, the computation of tree-level amplitudes in floating point or finite-field arithmetic, the numerical computation of one- and two-loop amplitudes in QCD and Einstein gravity, and functional reconstruction tools. We provide programs that showcase Caravel's main functionalities and allow to compute selected one- and two-loop amplitudes.
Published: 2020
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14. Resolving acceleration to very high energies along the Jet of Centaurus A

Author: Collaboration, The H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Colafrancesco, S., Curyło, M., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, N., Kosack, K., Kostunin, D., Kraus, M., Lamanna, G., Lau, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Mares, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Moulin, E., Muller, J., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H. M., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yonedak, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The nearby radio galaxy Centaurus A belongs to a class of Active Galaxies that are very luminous at radio wavelengths. The majority of these galaxies show collimated relativistic outflows known as jets, that extend over hundreds of thousands of parsecs for the most powerful sources. Accretion of matter onto the central super-massive black hole is believed to fuel these jets and power their emission, with the radio emission being related to the synchrotron radiation of relativistic electrons in magnetic fields. The origin of the extended X-ray emission seen in the kiloparsec-scale jets from these sources is still a matter of debate, although Cen A's X-ray emission has been suggested to originate in electron synchrotron processes. The other possible explanation is Inverse Compton (IC) scattering with CMB soft photons. Synchrotron radiation needs ultra-relativistic electrons ($\sim50$ TeV), and given their short cooling times, requires some continuous re-acceleration mechanism to be active. IC scattering, on the other hand, does not require very energetic electrons, but requires jets that stay highly relativistic on large scales ($\geq$1 Mpc) and that remain well-aligned with the line of sight. Some recent evidence disfavours inverse Compton-CMB models, although other evidence seems to be compatible with them. In principle, the detection of extended gamma-ray emission, directly probing the presence of ultra-relativistic electrons, could distinguish between these options, but instruments have hitherto been unable to resolve the relevant structures. At GeV energies there is also an unusual spectral hardening in Cen A, whose explanation is unclear. Here we report observations of Cen A at TeV energies that resolve its large-scale jet. We interpret the data as evidence for the acceleration of ultra-relativistic electrons in the jet, and favour the synchrotron explanation for the X-rays., Comment: 32 pages, 5 figure
Published: 2020
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15. Off-shell vs on-shell modelling of top quarks in photon associated production

Author: Bevilacqua, G., Hartanto, H. B., Kraus, M., Weber, T., and Worek, M.
Subjects: High Energy Physics - Phenomenology
Abstract: We present a comparative study of various approaches for modelling of the $e^+ \nu_e \mu^- \bar{\nu}_\mu b\bar{b} \gamma$ final state in $t\bar{t}\gamma$ production at the LHC. Working at the NLO in QCD we compare the fully realistic description of the top quark decay chain with the one provided by the narrow-width-approximation. The former approach comprises all double, single and non-resonant diagrams, interferences, and off-shell effects of the top quarks. The latter incorporates only double resonant contributions and restricts the unstable top quarks to on-shell states. We confirm that for the integrated cross sections the finite top quark width effects are small and of the order of ${\cal O}(\Gamma_t/m_t)$. We show, however, that they are strongly enhanced for more exclusive observables. In addition, we investigate fractions of events where the photon is radiated either in the production or in the decay stage. We find that large fraction of isolated photons comes from radiative decays of top quarks. Based on our findings, selection criteria might be developed to reduce such contributions, that constitute a background for the measurement of the anomalous couplings in the $t\bar{t}\gamma$ vertex., Comment: 31 pages, 11 figures, 2 tables, version to appear in JHEP
Published: 2019
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16. Creep damaged microstructure and mechanical properties of Cr–Mo–V steel subjected to long-term service exposures

Author: Négyesi, M., Kraus, M., Mareš, V., Kwon, D., and Strnadel, B.
Published: 2023
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17. H.E.S.S. detection of very-high-energy gamma-ray emission from the quasar PKS 0736+017

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Colafrancesco, S., Curylo, M., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kraus, M., Lamanna, G., Lau, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Mares, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Muller, J., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Oña, Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, L., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Zywucka, N., and Smith, P. S.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Flat-spectrum radio-quasars (FSRQs) are rarely detected at very-high-energies (VHE; E>100 GeV) due to their low-frequency-peaked SEDs. At present, only 6 FSRQs are known to emit VHE photons, representing only 7% of the VHE extragalactic catalog. Following the detection of MeV-GeV gamma-ray flaring activity from the FSRQ PKS 0736+017 (z=0.189) with Fermi, the H.E.S.S. array of Cherenkov telescopes triggered ToO observations on February 18, 2015, with the goal of studying the gamma-ray emission in the VHE band. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft-X-rays and optical/UV, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, the ATOM, the KAIT and the ASAS-SN telescope. VHE emission from PKS 0736+017 was detected with H.E.S.S. during the night of February 19, 2015, only. Fermi data indicate the presence of a gamma-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling time-scale of around six hours. The gamma-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The gamma-ray observations with H.E.S.S. and Fermi are used to put constraints on the location of the gamma-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line-region with a bulk Lorentz factor $\simeq 20$, or at the level of the radius of the dusty torus with Gamma > 60. PKS 0736+017 is the seventh FSRQ known to emit VHE photons and, at z=0.189, is the nearest so far. The location of the gamma-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments., Comment: In press in A&A. 13 pages, 5 figures. Abstract abridged
Published: 2019
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18. Resolving the Crab pulsar wind nebula at teraelectronvolt energies

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Arm, C., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Ch, T., Ch, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kraus, M., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., López-Coto, R., Lypova, I., Malyshev, D., Mar, V., Marcowith, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, R. M., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Crab nebula is one of the most studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very high-energy gamma rays. It is known from radio to gamma-ray observations that the nebula is powered by a pulsar, which converts most of its rotational energy losses into a highly relativistic outflow. This outflow powers a pulsar wind nebula (PWN), a region of up to 10~light-years across, filled with relativistic electrons and positrons. These particles emit synchrotron photons in the ambient magnetic field and produce very high-energy gamma rays by Compton up-scattering of ambient low-energy photons. While the synchrotron morphology of the nebula is well established, it was up to now not known in which region the very high-energy gamma rays are emitted. Here we report that the Crab nebula has an angular extension at gamma-ray energies of 52 arcseconds (assuming a Gaussian source width), significantly larger than at X-ray energies. This result closes a gap in the multi-wavelength coverage of the nebula, revealing the emission region of the highest energy gamma rays. These gamma rays are a new probe of a previously inaccessible electron and positron energy range. We find that simulations of the electromagnetic emission reproduce our new measurement, providing a non-trivial test of our understanding of particle acceleration in the Crab nebula., Comment: 23 pages, 5 figures
Published: 2019

19. A discrete Nambu bracket for 2D extended Magnetohydrodynamics

Author: Kaltsas, D. A., Kraus, M., and Throumoulopoulos, G. N.
Subjects: Physics - Plasma Physics
Abstract: In this note we propose a trilinear bracket formulation for the Hamiltonian extended Magnetohydrodynamics (XMHD) model with homogeneous mass density. The corresponding two-dimensional representation is derived by performing spatial reduction on the three-dimensional bracket, upon introducing a symmetric representation for the field variables. Subsequently, the trilinear bracket of the resulting two-dimensional, four-field model is discretized using a finite difference scheme, which results in semi-discrete dynamics that involve the Arakawa Jacobian. Simulations of planar dynamics show that this scheme respects the desired conservation properties to high precision.
Published: 2019
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20. An improved upper limit on the neutrino mass from a direct kinematic method by KATRIN

Author: Aker, M., Altenmüller, K., Arenz, M., Babutzka, M., Barrett, J., Bauer, S., Beck, M., Beglarian, A., Behrens, J., Bergmann, T., Besserer, U., Blaum, K., Block, F., Bobien, S., Bokeloh, K., Bonn, J., Bornschein, B., Bornschein, L., Bouquet, H., Brunst, T., Caldwell, T. S., La Cascio, L., Chilingaryan, S., Choi, W., Corona, T. J., Debowski, K., Deffert, M., Descher, M., Doe, P. J., Dragoun, O., Drexlin, G., Dunmore, J. A., Dyba, S., Edzards, F., Eisenblätter, L., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Felden, A., Fischer, S., Flatt, B., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Frankrone, H., Friedel, F., Fuchs, D., Fulst, A., Furse, D., Gauda, K., Gemmeke, H., Gil, W., Glück, F., Görhardt, S., Groh, S., Grohmann, S., Grössle, R., Gumbsheimer, R., Minh, M. Ha, Hackenjos, M., Hannen, V., Harms, F., Hartmann, J., Haußmann, N., Heizmann, F., Helbing, K., Hickford, S., Hilk, D., Hillen, B., Hillesheimer, D., Hinz, D., Höhn, T., Holzapfel, B., Holzmann, S., Houdy, T., Howe, M. A., Huber, A., Jansen, A., Kaboth, A., Karl, C., Kazachenko, O., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kosmider, A., Kovalí, A., Krasch, B., Kraus, M., Krause, H., Kuckert, L., Kuffner, B., Kunka, N., Lasserre, T., Le, T. L., Lebeda, O., Leber, M., Lehnert, B., Letnev, J., Leven, F., Lichter, S., Lobashev, V. M., Lokhov, A., Machatschek, M., Malcherek, E., Müller, K., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Menshikov, A., Mertens, S., Minter, L. I., Mirz, S., Monreal, B., Guzman, P. I. Morales, Naumann, U., Ndeke, W., Neumann, H., Niemes, S., Noe, M., Oblath, N. S., Ortjohann, H. -W., Osipowicz, A., Ostrick, B., Otten, E., Parno, D. S., Phillips II, D. G., Plischke, P., Pollithy, A., Poon, A. W. P., Pouryamout, J., Prall, M., Priester, F., Röllig, M., Röttele, C., Ranitzsch, P. C. -O., Rest, O., Rinderspacher, R., Robertson, R. G. H., Rodenbeck, C., Rohr, P., Roll, Ch., Rupp, S., Rysavy, M., Sack, R., Saenz, A., Schäfer, P., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schön, H., Schönung, K., Schrank, M., Schulz, B., Schwarz, J., Seitz-Moskaliuk, H., Seller, W., Sibille, V., Siegmann, D., Skasyrskaya, A., Slezak, M., Spalek, A., Spanier, F., Steidl, M., Steinbrink, N., Sturm, M., Suesser, M., Sun, M., Tcherniakhovski, D., Telle, H. H., Thümmler, T., Thorne, L. A., Titov, N., Tkachev, I., Trost, N., Urban, K., Venos, D., Valerius, K., VanDevender, B. A., Vianden, R., Hernandez, A. P. Vizcaya, Wall, B. L., Wüstling, S., Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wierman, K. J., Wilkerson, J. F., Wolf, J., Xu, W., Yen, Y. -R., Zacher, M., Zadorozhny, S., Zboril, M., and Zeller, G.
Subjects: High Energy Physics - Experiment, Astrophysics - Cosmology and Nongalactic Astrophysics, Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract: We report on the neutrino mass measurement result from the first four-week science run of the Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are energy analyzed by a high-resolution MAC-E filter. A fit of the integrated electron spectrum over a narrow interval around the kinematic endpoint at 18.57 keV gives an effective neutrino mass square value of $(-1.0^{+0.9}_{-1.1})$ eV$^2$. From this we derive an upper limit of 1.1 eV (90$\%$ confidence level) on the absolute mass scale of neutrinos. This value coincides with the KATRIN sensitivity. It improves upon previous mass limits from kinematic measurements by almost a factor of two and provides model-independent input to cosmological studies of structure formation.
Published: 2019
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21. Towards constraining Dark Matter at the LHC: Higher order QCD predictions for $t\bar{t}+Z(Z\to \nu_\ell \bar{\nu}_\ell)$

Author: Bevilacqua, G., Hartanto, H. B., Kraus, M., Weber, T., and Worek, M.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract: Triggered by ongoing dark matter searches in the top quark sector at the Large Hadron Collider we report on the calculation of the next-to-leading order QCD corrections to the Standard Model process $pp\to t\bar{t}+ Z(\to \nu_\ell \bar{\nu}_\ell)$. This calculation is based on matrix elements for $e^+\nu_e \, \mu^- \bar{\nu}_\mu \, b\bar{b} \, \nu_\tau \bar{\nu}_\tau$ production and includes all non-resonant diagrams, interferences, and off-shell effects of the top quarks. Non-resonant and off-shell effects due to the finite $W$-boson width are also consistently taken into account. As it is common for such studies, we present results for both integrated and differential cross sections for a few renormalisation and factorisation scale choices and three different parton distribution functions. Already with the fairly inclusive cut selection and independently of the scale choice and the parton distribution function non-flat differential ${\cal K}$-factors are obtained for $p_T^{miss}, \Delta \phi_{\ell\ell}, \Delta y_{\ell\ell}, \cos\theta_{\ell\ell}, H_T, H^\prime_T$ observables that are relevant for new physics searches. Good theoretical control over the Standard Model background is a fundamental prerequisite for a correct interpretation of possible signals of new physics that may arise in this channel. Thus, these observables need to be carefully reexamined in the presence of more exclusive cuts before any realistic strategies for the detection of new physics signal can be further developed., Comment: 36 pages, 14 figures, 4 tables, version to appear in JHEP
Published: 2019
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22. Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE gamma-ray observations with H.E.S.S

Author: Collaboration, H. E. S. S., Abdalla, H., Adam, R., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chand, T., Chandra, S., Chen, A., Colafrancesco, S., Curylo, M., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gate, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jardin-Blicq, A., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khelifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kraus, M., Lamanna, G., Lau, J., Lemiere, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Mares, A., Mariaud, C., Marti-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Moulin, E., Muller, J., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, L., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Zywucka, N., and Meyer, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract: The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy ($100\,$MeV$100\,$GeV) $\gamma$-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with $8.7\,\sigma$ significance above an energy threshold of $66\,$GeV. No VHE variability has been detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of $4.2\pm 0.3$. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole is estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at $r\gtrsim 1.7\times10^{17}\,$cm from the black hole, i.e., beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models are used to describe the evolution of the 2015 flare. Neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data are used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279., Comment: 20 pages, 12 figures, accepted by A&A
Published: 2019
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23. The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds

Author: Condori, C. A. H., Fernandes, M. Borges, Kraus, M., Panoglou, D., and Guerrero, C. A.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: We investigated 12 unclassified B[e] stars or candidates, 8 from the Galaxy, 2 from the Large Magellanic Cloud (LMC) and 2 from the Small Magellanic Cloud (SMC). Based on the analysis of high-resolution spectroscopic (FEROS) and photometric data, we confirmed the presence of the B[e] phenomenon for all objects of our sample, except for one (IRAS 07455-3143). We derived their effective temperature, spectral type, luminosity class, interstellar extinction and, using the distances from Gaia DR2, we obtained their bolometric magnitude, luminosity and radius. Modeling of the forbidden lines present in the FEROS spectra revealed information about the kinematics and geometry of the circumstellar medium of these objects. In addition, we analyzed the light curves of four stars, finding their most probable periods. The evolutionary stage of 11 stars of our sample is suggested from their position on the HR diagram, taking into account evolutionary tracks of stars with solar, LMC and SMC metallicities. As results, we identified B and B[e] supergiants, B[e] stars probably at the main sequence or close to its end, post-AGB and HAeB[e] candidates, and A[e] stars in the main sequence or in the pre-main sequence. However, our most remarkable results are the identification of the third A[e] supergiant (ARDB\,54, the first one in the LMC), and of an "LBV impostor" in the SMC (LHA 115-N82).
Published: 2019
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24. Upper Limits on Very-High-Energy Gamma-ray Emission from Core-Collapse Supernovae Observed with H.E.S.S

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Ashkar, H., Backes, M., Martins, V. Barbosa, Barnard, M., Becherini, Y., Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bregeon, J., Breuhaus, M., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chand, T., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Curylo, M., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Feijen, K., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kostunin, D., Kraus, M., Lamanna, G., Lau, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Levy, C., Lohse, T., Lypova, I., Mackey, J., Majumdar, J., Malyshev, D., Marandon, V., Marcowith, A., Mares, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Muller, J., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Wilhelmi, E. de Ona, Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Remy, Q., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., Żywucka, N., and Maxted, Nigel
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Young core-collapse supernovae with dense-wind progenitors may be able to accelerate cosmic-ray hadrons beyond the knee of the cosmic-ray spectrum, and this may result in measurable gamma-ray emission. We searched for gamma-ray emission from ten supernovae observed with the High Energy Stereoscopic System (H.E.S.S.) within a year of the supernova event. Nine supernovae were observed serendipitously in the H.E.S.S. data collected between December 2003 and December 2014, with exposure times ranging from 1.4 hours to 53 hours. In addition we observed SN 2016adj as a target of opportunity in February 2016 for 13 hours. No significant gamma-ray emission has been detected for any of the objects, and upper limits on the $>1$ TeV gamma-ray flux of the order of $\sim$10$^{-13}$ cm$^{-2}$s$^{-1}$ are established, corresponding to upper limits on the luminosities in the range $\sim$2 $\times$ 10$^{39}$ erg s$^{-1}$ to $\sim$1 $\times$ 10$^{42}$ erg s$^{-1}$. These values are used to place model-dependent constraints on the mass-loss rates of the progenitor stars, implying upper limits between $\sim$2 $\times 10^{-5}$ and $\sim$2 $\times 10^{-3}$M$_{\odot}$yr$^{-1}$ under reasonable assumptions on the particle acceleration parameters., Comment: Accepted for publication in A&A
Published: 2019
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25. H.E.S.S. observations of the flaring gravitationally lensed galaxy PKS 1830-211

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Anguener, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernloehr, K., Blackwell, R., Boettcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Buchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chand, T., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Atai, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Fuessling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzynski, K., Katsuragawa, M., Katz, U., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluzniak, W., Komin, Nu., Kosack, K., Kraus, M., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lopez-Coto, R., Lorentz, M., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Marti-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Puehlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schuessler, F., Schulz, A., Schutte, H, Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, L., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Voelk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, R. M., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Ziegler, A., Zorn, J., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: PKS 1830-211 is a known macrolensed quasar located at a redshift of z=2.5. Its high-energy gamma-ray emission has been detected with the Fermi-LAT instrument and evidence for lensing was obtained by several authors from its high-energy data. Observations of PKS 1830-211 were taken with the H.E.S.S. array of Imaging Atmospheric Cherenkov Telescopes in August 2014, following a flare alert by the Fermi- LAT collaboration. The H.E.S.S observations were aimed at detecting a gamma-ray flare delayed by 20-27 days from the alert flare, as expected from observations at other wavelengths. More than twelve hours of good quality data were taken with an analysis threshold of $\sim67$ GeV. The significance of a potential signal is computed as a function of the date as well as the average significance over the whole period. Data are compared to simultaneous observations by Fermi-LAT. No photon excess or significant signal is detected. An upper limit on PKS 1830-211 flux above 67 GeV is computed and compared to the extrapolation of the Fermi-LAT flare spectrum., Comment: Accepted for publication in MNRAS
Published: 2019
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26. High-resolution spectroscopy of gaseous $^\mathrm{83m}$Kr conversion electrons with the KATRIN experiment

Author: Altenmüller, K., Arenz, M., Baek, W. -J., Beck, M., Beglarian, A., Behrens, J., Bergmann, T., Berlev, A., Besserer, U., Blaum, K., Block, F., Bobien, S., Bode, T., Bornschein, B., Bornschein, L., Brunst, T., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Eversheim, D., Fedkevych, M., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gil, W., Glück, F., Ureña, A. Gonzalez, Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Hickford, S., Hilk, D., Hillesheimer, D., Hinz, D., Howe, M. A., Huber, A., Jansen, A., Kellerer, J., Kernert, N., Kippenbrock, L., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, M., Lasserre, T., Lebeda, O., Letnev, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Off, A., Osipowicz, A., Otten, E., Parno, D. S., Plischke, P., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Robertson, R. G. H., Roccati, F., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schönung, K., Schrank, M., Seitz-Moskaliuk, H., Sentkerestiová, J., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Suesser, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Weber, M., Weinheimer, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., Zadoroghny, S., and Zeller, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous $^\mathrm{83m}$Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The results obtained in this calibration measurement represent a major commissioning milestone for the upcoming direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the full KATRIN beamline. The KATRIN main spectrometer's excellent energy resolution of ~ 1 eV made it possible to determine the narrow K-32 and L$_3$-32 conversion electron line widths with an unprecedented precision of ~ 1 %., Comment: Fixed affiliation of the corresponding author
Published: 2019
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27. Gamma-induced background in the KATRIN main spectrometer

Author: Altenmüller, K., Arenz, M., Baek, W. -J., Beck, M., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Blaum, K., Block, F., Bobien, S., Bode, T., Bornschein, B., Bornschein, L., Bouquet, H., Brunst, T., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gil, W., Glück, F., Ureña, A. Gonzalez, Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Herz, W., Hickford, S., Hilk, D., Hillesheimer, D., Howe, M. A., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kernert, N., Kippenbrock, L., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, A., Kraus, M., Lasserre, T., Lebeda, O., Lehnert, B., Letnev, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Robertson, R. G. H., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schrank, M., Seitz-Moskaliuk, H., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Tcherniakhovski, D., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., Zadoroghny, S., and Zeller, G.
Subjects: Physics - Instrumentation and Detectors
Abstract: The KATRIN experiment aims to measure the effective electron antineutrino mass $m_{\overline{\nu}_e}$ with a sensitivity of 0.2 eV/c$^2$ using a gaseous tritium source combined with the MAC-E filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of 0.006 count/s (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.
Published: 2019
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28. Wind properties of variable B supergiants. Evidence of pulsations connected with mass-loss episodes

Author: Haucke, M., Cidale, L. S., Venero, R. O. J., Curé, M., Kraus, M., Kanaan, S., and Arcos, C.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: Variable B supergiants (BSGs) constitute a heterogeneous group of stars with complex photometric and spectroscopic behaviours. They exhibit mass-loss variations and experience different types of oscillation modes, and there is growing evidence that variable stellar winds and photospheric pulsations are closely related. To discuss the wind properties and variability of evolved B-type stars, we derive new stellar and wind parameters for a sample of 19 Galactic BSGs by fitting theoretical line profiles of H, He, and Si to the observed ones and compare them with previous determinations. The mass-loss rate of three stars has been obtained for the first time. All stars follow the known empirical wind momentum-luminosity relationships, and the late BSGs show the trend of the mid BSGs. We find an empirical relationship that associates the amplitude of mass-loss variations with photometric/spectroscopic variability on timescales of tens of days. We find that stars located on the cool side of the bi-stability jump show a decrease in the terminal and escape velocities ratio, while their corresponding mass-loss rates are similar to or lower than the values found for stars on the hot side. Particularly, for those variable stars a decrease in the terminal and escape velocities ratio is accompanied by a decrease in the mass-loss rate. Our results also suggest that radial pulsation modes with periods longer than 6 days might be responsible for the wind variability in the mid/late-type BSGs. These radial modes might be identified with strange modes, which are known to facilitate (enhanced) mass loss. On the other hand, we propose that the wind behaviour of stars on the cool side of the bi-stability jump could fit with predictions of the delta-slow hydrodynamics solution for radiation-driven winds with highly variable ionization.
Published: 2019
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29. The 2014 TeV Gamma-ray Flare of Mrk 501 Seen with H.E.S.S.: Temporal and Spectral Constraints on Lorentz Invariance Violation

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Martí-Devesa, G. Guillem, Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spanier, F., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Wörnlein, A., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: The blazar Mrk 501 (z=0.034) was observed at very-high-energy (VHE, $E\gtrsim 100$~GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data taken that night by H.E.S.S. at large zenith angle reveal an exceptional number of gamma-ray photons at multi-TeV energies, with rapid flux variability and an energy coverage extending significantly up to 20 TeV. This data set is used to constrain Lorentz invariance violation (LIV) using two independent channels: a temporal approach considers the possibility of an energy dependence in the arrival time of gamma rays, whereas a spectral approach considers the possibility of modifications to the interaction of VHE gamma rays with extragalactic background light (EBL) photons. The non-detection of energy-dependent time delays and the non-observation of deviations between the measured spectrum and that of a supposed power-law intrinsic spectrum with standard EBL attenuation are used independently to derive strong constraints on the energy scale of LIV ($E_{\rm{QG}}$) in the subluminal scenario for linear and quadratic perturbations in the dispersion relation of photons. For the case of linear perturbations, the 95% confidence level limits obtained are $E_{\rm{QG},1} > 3.6 \times 10^{17} \ \rm{GeV} $ using the temporal approach and $E_{\rm{QG},1} > 2.6 \times 10^{19} \ \rm{GeV}$ using the spectral approach. For the case of quadratic perturbations, the limits obtained are $E_{\rm{QG},2} > 8.5 \times 10^{10} \ \rm{GeV} $ using the temporal approach and $E_{\rm{QG},2} > 7.8 \times 10^{11} \rm{ GeV}$ using the spectral approach., Comment: Published in ApJ
Published: 2019
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30. High-resolution spectroscopy of gaseous 83mKr conversion electrons with the KATRIN experiment

Author: Altenmüller, K, Arenz, M, Baek, WJ, Beck, M, Beglarian, A, Behrens, J, Bergmann, T, Berlev, A, Besserer, U, Blaum, K, Block, F, Bobien, S, Bode, T, Bornschein, B, Bornschein, L, Brunst, T, Buzinsky, N, Chilingaryan, S, Choi, WQ, Deffert, M, Doe, PJ, Dragoun, O, Drexlin, G, Dyba, S, Edzards, F, Eitel, K, Ellinger, E, Engel, R, Enomoto, S, Eversheim, D, Fedkevych, M, Formaggio, JA, Fränkle, FM, Franklin, GB, Friedel, F, Fulst, A, Gil, W, Glück, F, Ureña, AG, Grohmann, S, Grössle, R, Gumbsheimer, R, Hackenjos, M, Hannen, V, Harms, F, Haußmann, N, Heizmann, F, Helbing, K, Hickford, S, Hilk, D, Hillesheimer, D, Hinz, D, Howe, MA, Huber, A, Jansen, A, Kellerer, J, Kernert, N, Kippenbrock, L, Klein, M, Kopmann, A, Korzeczek, M, Kovalík, A, Krasch, B, Kraus, M, Lasserre, T, Lebeda, O, Letnev, J, Lokhov, A, Machatschek, M, Marsteller, A, Martin, EL, Mertens, S, Mirz, S, Monreal, B, Neumann, H, Niemes, S, Off, A, Osipowicz, A, Otten, E, Parno, DS, Plischke, P, Pollithy, A, Poon, AWP, Priester, F, C-O Ranitzsch, P, Rest, O, Robertson, RGH, Roccati, F, Rodenbeck, C, Röllig, M, Röttele, C, Ryšavý, M, Sack, R, Saenz, A, Schimpf, L, Schlösser, K, Schlösser, M, Schönung, K, Schrank, M, and Seitz-Moskaliuk, H
Subjects: Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous 83mKr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The obtained results represent one of the major commissioning milestones for the subsequent direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the KATRIN beamline. Precise measurement of the narrow K-32, L3-32, and N2,3-32 conversion electron lines allowed to verify the eV-scale energy resolution of the KATRIN main spectrometer necessary for competitive measurement of the absolute neutrino mass scale.
Published: 2020

31. Post-thoracotomy Pain Syndrome

Author: Maloney, J., Wie, C., Pew, S., Covington, S., Maita, M., Kozinn, R., Sabin, M., Freeman, J., Kraus, M., and Strand, N.
Published: 2022
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32. Long-term persistence of HCV resistance-associated substitutions after DAA treatment failure

Author: Balavoine, J., Giostra, E., Berning, M., Hampe, J., Canbay, A., Steckstor, W., Schmiegel, W., Brockmeyer, N.H., De Gottardi, A., Rauch, A., Semmo, N., Fischer, J., Gress, M., Heinzow, H., Hilgard, G., Schmidt, H., Herrmann, A., Stallmach, A., Hoffmann, D., Protzer, U., Klinker, H., Schulze, P., Kodal, A., Kremer, A., Siebler, J., Löbermann, M., Götze, T., Weigt, J., Lohse, A., Von Felden, J., Jordan, S., Lange, C.M., Zachoval, R., Mayerle, J., Maieron, A., Moradpour, D., Chave, J.-P., Moreno, C., Muche, M., Epple, H.-J., Müller-Schilling, M., Kocheise, F., Müllhaupt, B., Port, K., Deterding, K., Wedemeyer, H., Cornberg, M., Manns, M., Reinhardt, L., Ellenrieder, V., Rissland, J., Semela, D., Spengler, U., Rockstroh, J., Roeb, E., Sprinzl, M., Galle, P., Stauber, R., Stremmel, W., Strey, B., Thimme, R., Boettler, T., Tacke, F., Teufel, A., Vogelmann, R., Ebert, M., Tomasiewicz, K., Trautwein, C., Koenen, T., Weber, T., Wietzke-Braun, P., Günther, R., Zizer, E., Backhus, J., Seufferlein, T., Angeli, W., Beckebaum, S., Doberauer, C., Durmashkina, E., Hackelsberger, A., Erhardt, A., Garrido-Lüneburg, A., Gattringer, H., Genné, D., Gschwantler, M., Gundling, F., Hametner, S., Schöfl, R., Hartmann, C., Heyer, T., Hirschi, C., Jussios, A., Kanzler, S., Kordecki, N., Kraus, M., Kullig, U., Wollschläger, S., Magenta, L., Terziroli Beretta-Piccoli, B., Menges, M., Mohr, L., Muehlenberg, K., Niederau, C., Paulweber, B., Petrides, A., Pinkernell, M., Piso, R., Rambach, W., Reiser, M., Riecken, B., Rieke, A., Roth, J., Schelling, M., Schlee, P., Schneider, A., Scholz, D., Schott, E., Schuchmann, M., Schulten-Baumer, U., Seelhoff, A., Stich, A., Stickel, F., Ungemach, J., Walter, E., Weber, A., Winzer, T., Abels, W., Adler, M., Audebert, F., Baermann, C., Bästlein, E., Barth, R., Barthel, K., Becker, W., Behrends, J., Benninger, J., Berger, F., Berzow, D., Beyer, T., Bierbaum, M., Blaukat, O., Bodtländer, A., Böhm, G., Börner, N., Bohr, U., Bokemeyer, B., Bruch, H.R., Bucholz, D., Burkhard, O., Busch, N., Chirca, C., Delker, R., Diedrich, J., Frank, M., Diehl, M., Dienethal, A., Dietel, P., Dikopoulos, N., Dreck, M., Dreher, F., Drude, L., Ende, K., Ehrle, U., Baumgartl, K., Emke, F., Glosemeyer, R., Felten, G., Hüppe, D., Fischer, U., Frederking, D., Frick, B., Friese, G., Gantke, B., Geyer, P., Schwind, H.R., Glas, M., Glaunsinger, T., Goebel, F., Göbel, U., Görlitz, B., Graf, R., Gruber, H., Härter, G., Herder, M., Heuchel, T., Heuer, S., Höffl, K.-H., Hörster, H., Sonne, J.-U., Hofmann, W.P., Holst, F., Hunstiger, M., Hurst, A., Jägel-Guedes, E., John, C., Jung, M., Kallinowski, B., Kapzan, B., Kerzel, W., Khaykin, P., Klarhof, M., Klüppelberg, U., Wolfratshausen, Klugewitz, K., Knapp, B., Knevels, U., Kochsiek, T., Körfer, A., Köster, A., Kuhn, M., Langekamp, A., Künzig, B., Link, R., Littman, M., Löhr, H., Lutz, T., Knecht, G., Lutz, U., Mainz, D., Mahle, I., Maurer, P., Mayer, C., Meister, V., Möller, H., Heyne, R., Moritzen, D., Mroß, M., Mundlos, M., Naumann, U., Nehls, O., Ningel, K.R., Oelmann, A., Olejnik, H., Gadow, K., Pascher, E., Petersen, J., Philipp, A., Pichler, M., Polzien, F., Raddant, R., Riedel, M., Rietzler, S., Rössle, M., Rufle, W., Rump, A., Schewe, C., Hoffmann, C., Schleehauf, D., Schmidt, W., Schmidt-Heinevetter, G., Schmidtler-von Fabris, J., Schneider, L., Schober, A., Niehaus-Hahn, S., Schwenzer, J., Seegers, B., Seidel, T., Seitel, G., Sick, C., Simon, K., Stähler, D., Stenschke, F., Steffens, H., Stein, K., Steinmüller, M., Sternfeld, T., Svensson, K., Tacke, W., Teuber, G., Teubner, K., Thieringer, J., Tomesch, A., Trappe, U., Ullrich, J., Urban, G., Usadel, S., Von Lucadou, A., Weinberger, F., Werheid-Dobers, M., Werner, P., Winter, T., Zehnter, E., Zipf, A., Dietz, Julia, Müllhaupt, Beat, Buggisch, Peter, Graf, Christiana, Peiffer, Kai-Henrik, Matschenz, Katrin, Schattenberg, Jörn M., Antoni, Christoph, Mauss, Stefan, Niederau, Claus, Discher, Thomas, Trauth, Janina, Dultz, Georg, Schulze zur Wiesch, Julian, Piecha, Felix, Klinker, Hartwig, Müller, Tobias, Berg, Thomas, Neumann-Haefelin, Christoph, Berg, Christoph P., Zeuzem, Stefan, and Sarrazin, Christoph
Published: 2023
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33. Particle Transport within the Pulsar Wind Nebula HESS J1825-137

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chand, T., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Kraus, M., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moore, C., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schutte, H., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, R. M., White, R., Wierzcholska, A., Yang, R., Yoneda, H., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Aims: We present a detailed view of the pulsar wind nebula (PWN) HESS J1825-137. We aim to constrain the mechanisms dominating the particle transport within the nebula, accounting for its anomalously large size and spectral characteristics. Methods: The nebula is studied using a deep exposure from over 12 years of H.E.S.S. I operation, together with data from H.E.S.S. II improving the low energy sensitivity. Enhanced energy-dependent morphological and spatially-resolved spectral analyses probe the Very High Energy (VHE, E > 0.1 TeV) gamma-ray properties of the nebula. Results: The nebula emission is revealed to extend out to 1.5 degrees from the pulsar, ~1.5 times further than previously seen, making HESS J1825--137, with an intrinsic diameter of ~100 pc, potentially the largest gamma-ray PWN currently known. Characterisation of the nebula's strongly energy-dependent morphology enables the particle transport mechanisms to be constrained. A dependence of the nebula extent with energy of R $\propto$ E^\alpha with \alpha = -0.29 +/- 0.04 (stat) +/- 0.05 (sys) disfavours a pure diffusion scenario for particle transport within the nebula. The total gamma-ray flux of the nebula above 1~TeV is found to be (1.12 +/- 0.03 (stat) +/- 0.25 (sys)) $\times 10^{-11}$ cm$^{-2}$ s$^{-1}$, corresponding to ~64% of the flux of the Crab Nebula. Conclusions: HESS J1825-137 is a PWN with clear energy-dependent morphology at VHE gamma-ray energies. This source is used as a laboratory to investigate particle transport within middle-aged PWNe. Deep observations of this highly spatially-extended PWN enable a spectral map of the region to be produced, providing insights into the spectral variation within the nebula., Comment: 20 pages, 10 figures, 5 tables, accepted for publication by Astronomy and Astrophysics
Published: 2018
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34. VHE $\gamma$-ray discovery and multi-wavelength study of the blazar 1ES 2322-409

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Martí-Devesa, G. Guillem, Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spanier, F., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Wörnlein, A., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: A hotspot at a position compatible with the BL Lac object 1ES 2322-409 was serendipitously detected with H.E.S.S. during observations performed in 2004 and 2006 on the blazar PKS 2316-423. Additional data on 1ES 2322-409 were taken in 2011 and 2012, leading to a total live-time of 22.3h. Point-like very-high-energy (VHE; E>100GeV) $\gamma$-ray emission is detected from a source centred on the 1ES 2322-409 position, with an excess of 116.7 events at a significance of 6.0$\sigma$. The average VHE $\gamma$-ray spectrum is well described with a power law with a photon index $\Gamma=3.40\pm0.66_{\text{stat}}\pm0.20_{\text{sys}}$ and an integral flux $\Phi(E>200GeV) = (3.11\pm0.71_{\rm stat}\pm0.62_{\rm sys})\times10^{-12} cm^{-2} s^{-1}$, which corresponds to 1.1$\%$ of the Crab nebula flux above 200 GeV. Multi-wavelength data obtained with Fermi LAT, Swift XRT and UVOT, RXTE PCA, ATOM, and additional data from WISE, GROND and Catalina, are also used to characterise the broad-band non-thermal emission of 1ES 2322-409. The multi-wavelength behaviour indicates day-scale variability. Swift UVOT and XRT data show strong variability at longer scales. A spectral energy distribution (SED) is built from contemporaneous observations obtained around a high state identified in Swift data. A modelling of the SED is performed with a stationary homogeneous one-zone synchrotron-self-Compton (SSC) leptonic model. The redshift of the source being unknown, two plausible values were tested for the modelling. A systematic scan of the model parameters space is performed, resulting in a well-constrained combination of values providing a good description of the broad-band behaviour of 1ES 2322-409., Comment: Accepted for publication in MNRAS. 13 pages, 8 figures
Published: 2018
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35. Searches for gamma-ray lines and `pure WIMP' spectra from Dark Matter annihilations in dwarf galaxies with H.E.S.S

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spanier, F., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, R. M., White, R., Wierzcholska, A., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., Żywucka, N., Cirelli, M., Panci, P., Sala, F., Silk, J., and Taoso, M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract: Dwarf spheroidal galaxies are among the most promising targets for detecting signals of Dark Matter (DM) annihilations. The H.E.S.S. experiment has observed five of these systems for a total of about 130 hours. The data are re-analyzed here, and, in the absence of any detected signals, are interpreted in terms of limits on the DM annihilation cross section. Two scenarios are considered: i) DM annihilation into mono-energetic gamma-rays and ii) DM in the form of pure WIMP multiplets that, annihilating into all electroweak bosons, produce a distinctive gamma-ray spectral shape with a high-energy peak at the DM mass and a lower-energy continuum. For case i), upper limits at 95\% confidence level of about $\langle \sigma v \rangle \lesssim 3 \times 10^{-25}$ cm$^3$ s$^{-1}$ are obtained in the mass range of 400 GeV to 1 TeV. For case ii), the full spectral shape of the models is used and several excluded regions are identified, but the thermal masses of the candidates are not robustly ruled out., Comment: Accepted for publication in JCAP. 18 pages, 7 figures
Published: 2018
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36. Precise predictions for $t\bar{t}\gamma/t\bar{t}$ cross section ratios at the LHC

Author: Bevilacqua, G., Hartanto, H. B., Kraus, M., Weber, T., and Worek, M.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract: With the goal of increasing the precision of NLO QCD predictions for the $pp\to t\bar{t} \gamma$ process in the di-lepton top quark decay channel we present theoretical predictions for the ${\cal R}= \sigma_{t\bar{t}\gamma}/\sigma_{t\bar{t}}$ cross section ratio. Results for the latter together with various differential cross section ratios are given for the LHC with the Run II energy of $\sqrt{s} = 13$ TeV. Fully realistic NLO computations for $t\bar{t}$ and $t\bar{t}\gamma$ production are employed. They are based on matrix elements for $e^+\nu_e \mu^- \bar{\nu}_\mu b\bar{b}$ and $e^+\nu_e \mu^- \bar{\nu}_\mu b\bar{b}\gamma$ processes and include all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the $W$ gauge bosons. Various renormalisation and factorisation scale choices and parton density functions are examined to assess their impact on the cross section ratio. Depending on the transverse momentum cut on the hard photon a judicious choice of a dynamical scale allows us to obtain $1\%-3\%$ percent precision on ${\cal R}$. Moreover, for differential cross section ratios theoretical uncertainties in the range of $1\%-6\%$ have been estimated. Until now such high precision predictions have only been reserved for the top quark pair production at NNLO QCD. Thus, ${\cal R}$ at NLO in QCD represents a very precise observable to be measured at the LHC for example to study the top quark charge asymmetry or to probe the strength and the structure of the $t$-$\bar{t}$-$\gamma$ vertex. The latter can shed some light on possible new physics that can reveal itself only once sufficiently precise theoretical predictions are available., Comment: 25 pages, 7 figures and 1 table, version to appear in JHEP
Published: 2018
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37. Relaxation to magnetohydrodynamics equilibria via collision brackets

Author: Bressan, C., Kraus, M., Morrison, P. J., and Maj, O.
Subjects: Physics - Plasma Physics
Abstract: Metriplectic dynamics is applied to compute equilibria of fluid dynamical systems. The result is a relaxation method in which Hamiltonian dynamics (symplectic structure) is combined with dissipative mechanisms (metric structure) that relaxes the system to the desired equilibrium point. The specific metric operator, which is considered in this work, is formally analogous to the Landau collision operator. These ideas are illustrated by means of case studies. The considered physical models are the Euler equations in vorticity form, the Grad-Shafranov equation, and force-free MHD equilibria., Comment: Conference Proceeding (Theory of Fusions Plasmas, 2018), 9 pages, 8 figures
Published: 2018
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38. On the evolutionary state of massive stars in transition phases in M33

Author: Kourniotis, M., Kraus, M., Arias, M. L., Cidale, L., and Torres, A. F.
Subjects: Astrophysics - Solar and Stellar Astrophysics
Abstract: The advanced stages of several high-mass stars are characterized by episodic mass loss shed during phases of instability. Key for assigning these stars a proper evolutionary state is to assess the composition and geometry of their ejecta alongside the stellar properties. We selected five hot LBV candidates in M33 to refine their classification, investigate their circumstellar environments and explore their evolutionary properties. Being accessible targets in the near-infrared, we conducted medium-resolution spectroscopy with GNIRS/GEMINI in the $K-$band to investigate their molecular circumstellar environments. Two stars were found to display CO emission, which was modeled to emerge from a circumstellar or circumbinary Keplerian disk/ring. The identification of the carbon isotope $^{13}$C and, for one of the two stars, a significantly low $^{12}$CO/$^{13}$CO ratio, implies an evolved stellar state. As both CO emission stars are highly luminous and hence do not undergo a red supergiant phase, we suggest that stripping processes and equatorial high-density ejecta due to fast rotation are responsible for the enrichment of the stellar surface with processed material from the core. A candidate B[e]SG displays an absorption CO profile, which may be attributed to a jet or stellar pulsations. The featureless infrared spectra of two stars suggest a low-density gas shell or dissipation of the molecule due to the ionizing temperature of the star. We propose spectroscopic monitoring of our targets to evaluate the stability of the CO molecule and assess the time-dependent dynamics of the circumstellar gas structures., Comment: 13 pages, 8 figures, 4 tables. MNRAS in press
Published: 2018
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39. The $\gamma$-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT

Author: Collaboration, H. E. S. S., Abdalla, H., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Armand, C., Arrieta, M., Backes, M., Balzer, A., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chaves, R. C. G., Chen, A., Chevalier, J., Colafrancesco, S., Condon, B., Conrad, J., Davids, I. D., Decock, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Donath, A., Drury, L. O'C., Dyks, J., Edwards, T., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Farnier, C., Fegan, S., Fernandes, M. V., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hawkes, J., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Ivascenko, A., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jingo, M., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Klochkov, D., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Laffon, H., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., Liu, R., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Marx, R., Maurin, G., Maxted, N., Mayer, M., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Morå, K., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Pekeur, N. W., Pelletier, G., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Rulten, C. B., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Seyffert, A. S., Shafi, N., Shilon, I., Simoni, K. Shiningayamwe. R., Sol, H., Spanier, F., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Willmann, P., Wörnlein, A., Wouters, D., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., Żywucka, N., collaboration, Fermi-LAT, Magill, J. D., Buson, S., Cheung, C. C., Perkins, J. S., and Tanaka, Y.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Centaurus A (Cen A) is the nearest radio galaxy discovered as a very-high-energy (VHE; 100 GeV-100 TeV) $\gamma$-ray source by the High Energy Stereoscopic System (H.E.S.S.). It is a faint VHE $\gamma$-ray emitter, though its VHE flux exceeds both the extrapolation from early Fermi-LAT observations as well as expectations from a (misaligned) single-zone synchrotron-self Compton (SSC) description. The latter satisfactorily reproduces the emission from Cen A at lower energies up to a few GeV. New observations with H.E.S.S., comparable in exposure time to those previously reported, were performed and eight years of Fermi-LAT data were accumulated to clarify the spectral characteristics of the $\gamma$-ray emission from the core of Cen A. The results allow us for the first time to achieve the goal of constructing a representative, contemporaneous $\gamma$-ray core spectrum of Cen A over almost five orders of magnitude in energy. Advanced analysis methods, including the template fitting method, allow detection in the VHE range of the core with a statistical significance of 12$\sigma$ on the basis of 213 hours of total exposure time. The spectrum in the energy range of 250 GeV-6 TeV is compatible with a power-law function with a photon index $\Gamma=2.52\pm0.13_{\mathrm{stat}}\pm0.20_{\mathrm{sys}}$. An updated Fermi-LAT analysis provides evidence for spectral hardening by $\Delta\Gamma\simeq0.4\pm0.1$ at $\gamma$-ray energies above $2.8^{+1.0}_{-0.6}$ GeV at a level of $4.0\sigma$. The fact that the spectrum hardens at GeV energies and extends into the VHE regime disfavour a single-zone SSC interpretation for the overall spectral energy distribution (SED) of the core and is suggestive of a new $\gamma$-ray emitting component connecting the high-energy emission above the break energy to the one observed at VHE energies., Comment: Accepted for publication in A&A, Abstract abridged for arXiv submission
Published: 2018
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40. First Ground-based Measurement of Sub-20 GeV to 100 GeV $\gamma$-rays from the Vela Pulsar with H.E.S.S. II

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Arm, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Ch, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Doroshenko, V., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Mar, V., Marcowith, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spanier, F., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, R. M., White, R., Wierzcholska, A., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., Żywucka, N., Kerr, M., Johnston, S., and Shannon, R. M.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on the measurement and investigation of pulsed high-energy $\gamma$-ray emission from the Vela pulsar, PSR B0833$-$45, based on 40.3 hours of observations with the largest telescope of H.E.S.S., CT5, in monoscopic mode, and on 8 years of data obtained with the Fermi-LAT. A dedicated very-low-threshold event reconstruction and analysis pipeline was developed and, together with the CT5 telescope response model, was validated using the Fermi-LAT data as reference. A pulsed $\gamma$-ray signal at a significance level of more than $15\sigma$ is detected from the P2 peak of the Vela pulsar light curve. Of a total of 15835 events, more than 6000 lie at an energy below 20 GeV, implying a significant overlap between H.E.S.S. II-CT5 and the Fermi-LAT. While the investigation of the pulsar light curve with the LAT confirms characteristics previously known up to 20 GeV, in the tens of GeV energy range, CT5 data show a change in the pulse morphology of P2, i.e., an extreme sharpening of its trailing edge, together with the possible onset of a new component at 3.4$\sigma$ significance level. Assuming a power-law model for the P2 spectrum, an excellent agreement is found for the photon indices ($\Gamma \simeq$ 4.1) obtained with the two telescopes above 10 GeV and an upper bound of 8% is derived on the relative offset between their energy scales. Using both instruments data, it is however shown that the spectrum of P2 in the 10-100 GeV has a pronounced curvature, i.e. a confirmation of the sub-exponential cutoff form found at lower energies with the LAT. This is further supported by the weak evidence for an emission above 100 GeV obtained with CT5. In contrast, converging indications are found from both CT5 and LAT data for the emergence of a hard component above 50 GeV in the leading wing (LW2) of P2, which possibly extends beyond 100 GeV., Comment: Accepted for publication in A&A. 16 Pages, 9 figures (slightly language edited version)
Published: 2018
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41. Characterisation and Testing of CHEC-M - a camera prototype for the Small-Sized Telescopes of the Cherenkov Telescope Array

Author: Zorn, J., White, R., Watson, J. J., Armstrong, T. P., Balzer, A., Barcelo, M., Berge, D., Bose, R., Brown, A. M., Bryan, M., Chadwick, P. M., Clark, P., Costantini, H., Cotter, G., Dangeon, L., Daniel, M., De Franco, A., Deiml, P., Fasola, G., Funk, S., Gebyehu, M., Gironnet, J., Graham, J. A., Greenshaw, T., Hinton, J. A., Kraus, M., Lapington, J. S., Laporte, P., Leach, S. A., Blanc, O. Le, Malouf, A., Molyneux, P., Moore, P., Prokoph, H., Okumura, A., Ross, D., Rowell, G., Sapozhnikov, L., Schoorlemmer, H., Sol, H., Stephan, M., Tajima, H., Tibaldo, L., Varner, G., and Zink, A.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The Compact High Energy Camera (CHEC) is a camera design for the Small-Sized Telescopes (SSTs; 4 m diameter mirror) of the Cherenkov Telescope Array (CTA). The SSTs are focused on very-high-energy $\gamma$-ray detection via atmospheric Cherenkov light detection over a very large area. This implies many individual units and hence cost-effective implementation. CHEC relies on dual-mirror optics to reduce the plate-scale and make use of 6 $\times$ 6 mm$^2$ pixels, leading to a low-cost ($\sim$150 kEuro), compact (0.5 m $\times$ 0.5 m), and light ($\sim$45 kg) camera with 2048 pixels providing a camera FoV of $\sim$9 degrees. The electronics are based on custom TARGET (TeV array readout with GSa/s sampling and event trigger) ASICs and FPGAs sampling incoming signals at a gigasample per second, with flexible camera-level triggering within a single backplane FPGA. CHEC is designed to observe in the $\gamma$-ray energy range of 1$-$300 TeV, and at impact distances up to $\sim$500 m. To accommodate this and provide full flexibility for later data analysis, full waveforms with 96 samples for all 2048 pixels can be read out at rates up to $\sim$900 Hz. The first prototype, CHEC-M, based on multi-anode photomultipliers (MAPMs) as photosensors, was commissioned and characterised in the laboratory and during two measurement campaigns on a telescope structure at the Paris Observatory in Meudon. In this paper, the results and conclusions from the laboratory and on-site testing of CHEC-M are presented. They have provided essential input on the system design and on operational and data analysis procedures for a camera of this type. A second full-camera prototype based on Silicon photomultipliers (SiPMs), addressing the drawbacks of CHEC-M identified during the first prototype phase, has already been built and is currently being commissioned and tested in the laboratory.
Published: 2018
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42. The KATRIN Superconducting Magnets: Overview and First Performance Results

Author: Arenz, M., Baek, W. -J., Beck, M., Beglarian, A., Behrens, J., Bergmann, T., Berlev, A., Besserer, U., Blaum, K., Bode, T., Bornschein, B., Bornschein, L., Brunst, T., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gil, n W., Glück, F., Ureña, A. Gonzalez, Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Herz, W., Hickford, S., Hilk, D., Howe, M. A., Huber, A., Jansen, A., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, M., Kuckert, L., Lasserre, T., Lebeda, O., Letnev, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Off, A., Osipowicz, A., Otten, uE., Parno, D. S., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Robertson, R. G. H., Roccati, F., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schönung, K., Schrank, M., Seitz-Moskaliuk, H., Sentkerestiová, J., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., and Zadoroghny, S.
Subjects: Physics - Instrumentation and Detectors
Abstract: The KATRIN experiment aims for the determination of the effective electron anti-neutrino mass from the tritium beta-decay with an unprecedented sub-eV sensitivity. The strong magnetic fields, designed for up to 6~T, adiabatically guide $\beta$-electrons from the source to the detector within a magnetic flux of 191~Tcm$^2$. A chain of ten single solenoid magnets and two larger superconducting magnet systems have been designed, constructed, and installed in the 70-m-long KATRIN beam line. The beam diameter for the magnetic flux varies from 0.064~m to 9~m, depending on the magnetic flux density along the beam line. Two transport and tritium pumping sections are assembled with chicane beam tubes to avoid direct "line-of-sight" molecular beaming effect of gaseous tritium molecules into the next beam sections. The sophisticated beam alignment has been successfully cross-checked by electron sources. In addition, magnet safety systems were developed to protect the complex magnet systems against coil quenches or other system failures. The main functionality of the magnet safety systems has been successfully tested with the two large magnet systems. The complete chain of the magnets was operated for several weeks at 70$\%$ of the design fields for the first test measurements with radioactive krypton gas. The stability of the magnetic fields of the source magnets has been shown to be better than 0.01$\%$ per month at 70$\%$ of the design fields. This paper gives an overview of the KATRIN superconducting magnets and reports on the first performance results of the magnets.
Published: 2018
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43. The starburst galaxy NGC 253 revisited by H.E.S.S. and Fermi-LAT

Author: Collaboration, H. E. S. S., Abdalla, H., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arcaro, C., Armand, C., Arrieta, M., Backes, M., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Bylund, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chandra, S., Chaves, R. C. G., Chen, A., Colafrancesco, S., Condon, B., Davids, I. D., Deil, C., Devin, J., de Wilt, P., Dirson, L., Djannati-Ataï, A., Dmytriiev, A., Donath, A., Drury, L. O'C., Dyks, J., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Fegan, S., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Huber, D., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Kluźniak, W., Komin, N., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Lamanna, G., Lau, J., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Martí-Devesa, G., Marx, R., Maurin, G., Meintjes, P. J., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Noel, A. Priyana, Prokhorov, D. A., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Ruiz-Velasco, E., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Senniappan, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sinha, A., Sol, H., Spanier, F., Specovius, A., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Wörnlein, A., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: (Abridged) Context. NGC 253 is one of only two starburst galaxies found to emit $\gamma$-rays from hundreds of MeV to multi-TeV energies. Accurate measurements of the very-high-energy (VHE) (E $>$ 100 GeV) and high-energy (HE) (E $>$ 60 MeV) spectra are crucial to study the underlying particle accelerators and cosmic-ray interaction and transport. Aims. The measurement of the VHE $\gamma$-ray emission of NGC 253 published in 2012 by H.E.S.S. was limited by large systematic uncertainties. Here, a measurement of the $\gamma$-ray spectrum of NGC 253 is investigated in both HE and VHE $\gamma$-rays. Methods. The data of H.E.S.S. observations are reanalysed using an updated calibration and analysis chain. The $Fermi$-LAT analysis employs more than 8 years of data processed using pass 8. The cosmic-ray particle population is evaluated from the combined HE--VHE $\gamma$-ray spectrum using NAIMA. Results. The VHE $\gamma$-ray energy spectrum is best fit by a power-law with a flux normalisation of $(1.34\,\pm\,0.14^{\mathrm{stat}}\,\pm\,0.27^{\mathrm{sys}}) \times 10^{-13} \mathrm{cm^{-2} s^{-1} TeV^{-1}}$ at 1 TeV -- about 40 \% above, but compatible with the value obtained in Abramowski et al. (2012). The spectral index $\Gamma = 2.39 \pm 0.14^{\mathrm{stat}} \pm 0.25^{\mathrm{sys}}$ is slightly softer than but consistent with the previous measurement. At energies above $\sim$3 GeV the HE spectrum is consistent with a power-law ranging into the VHE part of the spectrum measured by H.E.S.S. Conclusions. Two scenarios for the starburst nucleus are tested, in which the gas in the starburst nucleus acts as a target for hadronic cosmic rays. In these two models, the level to which NGC\,253 acts as a calorimeter is estimated to a range of $f_{\rm cal} = 0.1$ to $1$ while accounting for the measurement uncertainties., Comment: Accepted by A&A, 8 pages, 2 figures, 2 tables
Published: 2018
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44. Muon-induced background in the KATRIN main spectrometer

Author: Altenmüller, K., Arenz, M., Baek, W. -J., Beck, M., Beglarian, A., Behrens, J., Bergmann, T., Berlev, A., Besserer, U., Blaum, K., Bobien, S., Bode, T., Bornschein, B., Bornschein, L., Brunst, T., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gil, W., Glück, F., Ureña, A. Gonzalez, Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Herz, W., Hickford, S., Hilk, D., Hillesheimer, D., Howe, M. A., Huber, A., Jansen, A., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, M., Kuckert, L., Lasserre, T., Lebeda, O., Leiber, B., Letnev, J., Linek, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Off, A., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Rink, R., Robertson, R. G. H., Roccati, F., Rodenbeck, C., Röllig, M., Röttele, C., Rovedo, P., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schönung, K., Schrank, M., Seitz-Moskaliuk, H., Sentkerestiová, J., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Suesser, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Wandkowsky, N., Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., Zadoroghny, S., and Zeller, G.
Subjects: Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract: The KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c$^{2}$. It investigates the kinematics of $\beta$-particles from tritium $\beta$-decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about $12\%$ of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than $17\%$ ($90\%$ confidence level) of the overall MS background.
Published: 2018
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45. Search for $\gamma$-ray line signals from dark matter annihilations in the inner Galactic halo from ten years of observations with H.E.S.S

Author: Collaboration, H. E. S. S., Abdallah, H., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arrieta, M., Aubert, P., Backes, M., Balzer, A., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Capasso, M., Caroff, S., Carosi, A., Carr, J., Casanova, S., Cerruti, M., Chakraborty, N., Chaves, R. C. G., Chen, A., Chevalier, J., Colafrancesco, S., Condon, B., Conrad, J., Davids, I. D., Decock, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Domainko, W., Donath, A., Drury, L. O'C., Dutson, K., Dyks, J., Edwards, T., Egberts, K., Eger, P., Emery, G., Ernenwein, J. P., Eschbach, S., Farnier, C., Fegan, S., Fernandes, M. V., Fiasson, A., Fontaine, G., Förster, A., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Giebels, B., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. H., Hahn, J., Haupt, M., Hawkes, J., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Holch, T. L., Holler, M., Horns, D., Ivascenko, A., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Janiak, M., Jankowsky, D., Jankowsky, F., Jingo, M., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Klochkov, D., Kluźniak, W., Komin, N., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Laffon, H., Lamanna, G., Lau, J., Lees, J. P., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. P., Leser, E., Liu, R., Lohse, T., Lorentz, M., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Marx, R., Maurin, G., Maxted, N., Mayer, M., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Morå, K., Moulin, E., Murach, T., Nakashima, S., de Naurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Pekeur, N. W., Pelletier, G., Perennes, C., Petrucci, P. O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Poon, H., Prokhorov, D., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Rulten, C. B., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schandri, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Settimo, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sol, H., Spanier, F., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Willmann, P., Wörnlein, A., Wouters, D., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Zywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy $\gamma$-rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of signal versus background. The analysis makes use of Galactic Center (GC) observations accumulated over ten years (2004 - 2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant $\gamma$-ray excess above the background is found. We derive upper limits on the annihilation cross section $\langle\sigma v\rangle$ for monoenergetic DM lines at the level of $\sim4\times10^{-28}$ cm$^{3}$s$^{-1}$ at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of six. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV - 70 TeV. Ground-based $\gamma$-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two $\gamma$-ray photons at the level expected from the thermal relic density for TeV DM particles., Comment: Accepted by Phys. Rev. Lett. Includes Supplemental Material. 8+4 pages, 3+3 figures, 2 tables
Published: 2018
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46. Reduction of stored-particle background by a magnetic pulse method at the KATRIN experiment

Author: KATRIN Collaboration, Arenz, M., Baek, W. -J., Bauer, S., Beck, M., Beglarian, A., Behrens, J., Berendes, R., Bergmann, T., Berlev, A., Besserer, U., Blaum, K., Bode, T., Bornschein, B., Bornschein, L., Brunst, T., Buglak, W., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Furse, D., Gil, W., Glück, F., Urena, A. Gonzalez, Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Herz, W., Hickford, S., Hilk, D., Howe, M. A., Huber, A., Jansen, A., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, M., Kuckert, L., Lasserre, T., Lebeda, O., Letnev, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Off, A., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Robertson, R. G. H., Roccati, F., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schönung, K., Schrank, M., Seitz-Moskaliuk, H., Sentkerestiová, J., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Wandkowsky, N., Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., and Zadoroghny, S.
Subjects: Physics - Instrumentation and Detectors
Abstract: The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of $0.2\,{\text{eV}/c^2}$ (90\% C.L.) by precision measurement of the shape of the tritium \textbeta-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. A common background source in this setup is the decay of short-lived isotopes, such as $\textsuperscript{219}$Rn and $\textsuperscript{220}$Rn, in the spectrometer volume. Active and passive countermeasures have been implemented and tested at the KATRIN main spectrometer. One of these is the magnetic pulse method, which employs the existing air coil system to reduce the magnetic guiding field in the spectrometer on a short timescale in order to remove low- and high-energy stored electrons. Here we describe the working principle of this method and present results from commissioning measurements at the main spectrometer. Simulations with the particle-tracking software Kassiopeia were carried out to gain a detailed understanding of the electron storage conditions and removal processes., Comment: 16 pages, 9 figures, 4 tables
Published: 2018
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47. Hard Photons in Hadroproduction of Top Quarks with Realistic Final States

Author: Bevilacqua, G., Hartanto, H. B., Kraus, M., Weber, T., and Worek, M.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract: We present a complete description of top quark pair production in association with a hard photon in the dilepton channel. Our calculation is accurate to NLO in QCD. It is based on matrix elements for $e^+\nu_e \mu^-\bar{\nu}_\mu b \bar{b}\gamma$ production and includes all resonant and non-resonant diagrams, interferences, and off-shell effects of the top quarks and the $W$ gauge bosons. This calculation constitutes the first full computation for top quark pair production with a final state photon in hadronic collisions at NLO in QCD. Numerical results for total and differential cross sections are presented for the LHC at a centre-of-mass energy of $\sqrt{s}=13$ TeV. For a few observables relevant for new physics searches, beyond some kinematic bounds, we observe shape distortions of more than $100\%$. In addition, we confirm that the size of the top quark off-shell effects for the total cross section is consistent with the expected uncertainties of the narrow width approximation. Results presented here are not only relevant for beyond the Standard Model physics searches but also important for precise measurements of the top-quark fiducial cross sections and top-quark properties at the LHC., Comment: 23 pages, 10 figures, the fixed scale results extended, new results with the dynamic scale added, version to appear in JHEP
Published: 2018
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48. H.E.S.S. discovery of very high energy gamma-ray emission from PKS 0625-354

Author: Collaboration, H. E. S. S., Abdalla, H., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Akhperjanian, A. G., Andersson, T., Angüner, E. O., Arrieta, M., Aubert, P., Backes, M., Balzer, A., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Bulik, T., Capasso, M., Carr, J., Casanova, S., Cerruti, M., Chakraborty, N., Chalme-Calvet, R., Chaves, R. C. G., Chen, A., Chevalier, J., Chrétien, M., Colafrancesco, S., Cologna, G., Condon, B., Conrad, J., Cui, Y., Davids, I. D., Decock, J., Degrange, B., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Domainko, W., Donath, A., Drury, L. O'C., Dubus, G., Dutson, K., Dyks, J., Dyrda, M., Edwards, T., Egberts, K., Eger, P., Ernenwein, J. -P., Eschbach, S., Farnier, C., Fegan, S., Fernandes, M. V., Fiasson, A., Fontaine, G., Förster, A., Funk, S., Füßling, M., Gabici, S., Gajdus, M., Gallant, Y. A., Garrigoux, T., Giavitto, G., Giebels, B., Glicenstein, J. F., Gottschall, D., Goyal, A., Grondin, M. -H., Hadasch, D., Hahn, J., Haupt, M., Hawkes, J., Heinzelmann, G., Henri, G., Hermann, G., Hervet, O., Hinton, J. A., Hofmann, W., Hoischen, C., Holler, M., Horns, D., Ivascenko, A., Jacholkowska, A., Jamrozy, M., Janiak, M., Jankowsky, D., Jankowsky, F., Jingo, M., Jogler, T., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katz, U., Kerszberg, D., Khélifi, B., Kieffer, M., King, J., Klepser, S., Klochkov, D., Kluźniak, W., Kolitzus, D., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krayzel, F., Krüger, P. P., Laffon, H., Lamanna, G., Lau, J., Lees, J. -P., Lefaucheur, J., Lefranc, V., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., Liu, R., López-Coto, R., Lypova, I., Marandon, V., Marcowith, A., Mariaud, C., Marx, R., Maurin, G., Maxted, N., Mayer, M., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Morå, K., Moulin, E., Murach, T., de Naurois, M., Niederwanger, F., Niemiec, J., Oakes, L., O'Brien, P., Odaka, H., Öttl, S., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Pekeur, N. W., Pelletier, G., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poon, H., Prokhorov, D., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Romoli, C., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Sahakian, V., Salek, D., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Settimo, M., Seyffert, A. S., Shafi, N., Shilon, I., Simoni, R., Sol, H., Spanier, F., Spengler, G., Spies, F., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Stycz, K., Sushch, I., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Willmann, P., Wörnlein, A., Wouters, D., Yang, R., Zabalza, V., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: PKS 0625-354 (z=0.055) was observed with the four H.E.S.S. telescopes in 2012 during 5.5 hours. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1$\sigma$. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index $\Gamma =2.84 \pm 0.50_{stat} \pm 0.10_{syst}$ and normalization (at $E_0$=1.0 TeV) $N_0(E_0)=(0.58 \pm 0.22_{stat} \pm 0.12_{syst})\times10^{-12}$ TeV$^{-1}$cm$^{-2}$s$^{-1}$. Multi-wavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT $\gamma$-ray and Swift-XRT X-ray energy bands. Having a good multi-wavelength coverage from radio to very high energy, we performed a broadband modelling from two types of emission scenarios. The results from a one zone lepto-hadronic, and a multi-zone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multi-zone model. Models associated to the X-ray variability constraint supports previous results suggesting a BL Lac nature of PKS 0625-354, with, however, a large-scale jet structure typical of a radio galaxy., Comment: 13 pages, 6 figures, accepted for publication in MNRAS
Published: 2018
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49. Population study of Galactic supernova remnants at very high $\gamma$-ray energies with H.E.S.S.

Author: Collaboration, H. E. S. S., Abdalla, H., Abramowski, A., Aharonian, F., Benkhali, F. Ait, Angüner, E. O., Arakawa, M., Arrieta, M., Aubert, P., Backes, M., Balzer, A., Barnard, M., Becherini, Y., Tjus, J. Becker, Berge, D., Bernhard, S., Bernlöhr, K., Blackwell, R., Böttcher, M., Boisson, C., Bolmont, J., Bonnefoy, S., Bordas, P., Bregeon, J., Brun, F., Brun, P., Bryan, M., Büchele, M., Bulik, T., Capasso, M., Caroff, S., Carosi, A., Casanova, S., Cerruti, M., Chakraborty, N., Chaves, R. C. G., Chen, A., Chevalier, J., Colafrancesco, S., Condon, B., Conrad, J., Davids, I. D., Decock, J., Deil, C., Devin, J., deWilt, P., Dirson, L., Djannati-Ataï, A., Donath, A., Drury, L. O'C., Dutson, K., Dyks, J., Edwards, T., Egberts, K., Emery, G., Ernenwein, J. -P., Eschbach, S., Farnier, C., Fegan, S., Fernandes, M. V., Fernandez, D., Fiasson, A., Fontaine, G., Funk, S., Füßling, M., Gabici, S., Gallant, Y. A., Garrigoux, T., Gaté, F., Giavitto, G., Giebels, B., Glawion, D., Glicenstein, J. F., Gottschall, D., Grondin, M. -H., Hahn, J., Haupt, M., Hawkes, J., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hofmann, W., Hoischen, C., Holch, T. L., Holler, M., Horns, D., Ivascenko, A., Iwasaki, H., Jacholkowska, A., Jamrozy, M., Jankowsky, D., Jankowsky, F., Jingo, M., Jouvin, L., Jung-Richardt, I., Kastendieck, M. A., Katarzyński, K., Katsuragawa, M., Katz, U., Kerszberg, D., Khangulyan, D., Khélifi, B., King, J., Klepser, S., Klochkov, D., Kluźniak, W., Komin, Nu., Kosack, K., Krakau, S., Kraus, M., Krüger, P. P., Laffon, H., Lamanna, G., Lau, J., Lees, J. -P., Lefaucheur, J., Lemière, A., Lemoine-Goumard, M., Lenain, J. -P., Leser, E., Lohse, T., Lorentz, M., Liu, R., López-Coto, R., Lypova, I., Malyshev, D., Marandon, V., Marcowith, A., Mariaud, C., Marx, R., Maurin, G., Maxted, N., Mayer, M., Meintjes, P. J., Meyer, M., Mitchell, A. M. W., Moderski, R., Mohamed, M., Mohrmann, L., Morå, K., Moulin, E., Murach, T., Nakashima, S., deNaurois, M., Ndiyavala, H., Niederwanger, F., Niemiec, J., Oakes, L., OBrien, P., Odaka, H., Ohm, S., Ostrowski, M., Oya, I., Padovani, M., Panter, M., Parsons, R. D., Pekeur, N. W., Pelletier, G., Perennes, C., Petrucci, P. -O., Peyaud, B., Piel, Q., Pita, S., Poireau, V., Poon, H., Prokhorov, D., Prokoph, H., Pühlhofer, G., Punch, M., Quirrenbach, A., Raab, S., Rauth, R., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Rinchiuso, L., Romoli, C., Rowell, G., Rudak, B., Rulten, C. B., Safi-Harb, S., Sahakian, V., Saito, S., Sanchez, D. A., Santangelo, A., Sasaki, M., Schlickeiser, R., Schüssler, F., Schulz, A., Schwanke, U., Schwemmer, S., Seglar-Arroyo, M., Settimo, M., Seyffert, A. S., Shafi, N., Shilon, I., Shiningayamwe, K., Simoni, R., Sol, H., Spanier, F., Spir-Jacob, M., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steppa, C., Sushch, I., Takahashi, T., Tavernet, J. -P., Tavernier, T., Taylor, A. M., Terrier, R., Tibaldo, L., Tiziani, D., Tluczykont, M., Trichard, C., Tsirou, M., Tsuji, N., Tuffs, R., Uchiyama, Y., van der Walt, D. J., van Eldik, C., van Rensburg, C., van Soelen, B., Vasileiadis, G., Veh, J., Venter, C., Viana, A., Vincent, P., Vink, J., Voisin, F., Völk, H. J., Vuillaume, T., Wadiasingh, Z., Wagner, S. J., Wagner, P., Wagner, R. M., White, R., Wierzcholska, A., Willmann, P., Wörnlein, A., Wouters, D., Yang, R., Zaborov, D., Zacharias, M., Zanin, R., Zdziarski, A. A., Zech, A., Zefi, F., Ziegler, A., Zorn, J., and Żywucka, N.
Subjects: Astrophysics - High Energy Astrophysical Phenomena
Abstract: Shell-type supernova remnants (SNRs) are considered prime candidates for the acceleration of Galactic cosmic rays (CRs) up to the knee of the CR spectrum at $\mathrm{E} \approx \mathrm{3}\times \mathrm{10}^\mathrm{15}$ eV. Our Milky Way galaxy hosts more than 350 SNRs discovered at radio wavelengths and at high energies, of which 220 fall into the H.E.S.S. Galactic Plane Survey (HGPS) region. Of those, only 50 SNRs are coincident with a H.E.S.S source and in 8 cases the very high-energy (VHE) emission is firmly identified as an SNR. The H.E.S.S. GPS provides us with a legacy for SNR population study in VHE $\gamma$-rays and we use this rich data set to extract VHE flux upper limits from all undetected SNRs. Overall, the derived flux upper limits are not in contradiction with the canonical CR paradigm. Assuming this paradigm holds true, we can constrain typical ambient density values around shell-type SNRs to $n\leq 7~\textrm{cm}^\textrm{-3}$ and electron-to-proton energy fractions above 10~TeV to $\epsilon_\textrm{ep} \leq 5\times 10^{-3}$. Furthermore, comparisons of VHE with radio luminosities in non-interacting SNRs reveal a behaviour that is in agreement with the theory of magnetic field amplification at shell-type SNRs., Comment: 20 pages, 11 figures, 4 tables. Accepted for publication in A&A
Published: 2018
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50. Calibration of high voltages at the ppm level by the difference of $^{83\mathrm{m}}$Kr conversion electron lines at the KATRIN experiment

Author: Arenz, M., Baek, W. -J., Beck, M., Beglarian, A., Behrens, J., Bergmann, T., Berlev, A., Besserer, U., Blaum, K., Bode, T., Bornschein, B., Bornschein, L., Brunst, T., Buzinsky, N., Chilingaryan, S., Choi, W. Q., Deffert, M., Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Erhard, M., Eversheim, D., Fedkevych, M., Fischer, S., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gil, W., Glück, F., Ureña, A. Gonzalez, Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Harms, F., Haußmann, N., Heizmann, F., Helbing, K., Herz, W., Hickford, S., Hilk, D., Hillesheimer, D., Howe, M. A., Huber, A., Jansen, A., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Kraus, M., Kuckert, L., Lasserre, T., Lebeda, O., Letnev, J., Lokhov, A., Machatschek, M., Marsteller, A., Martin, E. L., Mertens, S., Mirz, S., Monreal, B., Neumann, H., Niemes, S., Off, A., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Priester, F., Ranitzsch, P. C. -O., Rest, O., Robertson, R. G. H., Roccati, F., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schimpf, L., Schlösser, K., Schlösser, M., Schönung, K., Schrank, M., Seitz-Moskaliuk, H., Sentkerestiová, J., Sibille, V., Slezák, M., Steidl, M., Steinbrink, N., Sturm, M., Suchopar, M., Suesser, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Valerius, K., Vénos, D., Vianden, R., Hernández, A. P. Vizcaya, Weber, M., Weinheimer, C., Weiss, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., and Zadoroghny, S.
Subjects: Physics - Instrumentation and Detectors
Abstract: The neutrino mass experiment KATRIN requires a stability of 3 ppm for the retarding potential at -18.6 kV of the main spectrometer. To monitor the stability, two custom-made ultra-precise high-voltage dividers were developed and built in cooperation with the German national metrology institute Physikalisch-Technische Bundesanstalt (PTB). Until now, regular absolute calibration of the voltage dividers required bringing the equipment to the specialised metrology laboratory. Here we present a new method based on measuring the energy difference of two $^{83\mathrm{m}}$Kr conversion electron lines with the KATRIN setup, which was demonstrated during KATRIN's commissioning measurements in July 2017. The measured scale factor $M=1972.449(10)$ of the high-voltage divider K35 is in agreement with the last PTB calibration four years ago. This result demonstrates the utility of the calibration method, as well as the long-term stability of the voltage divider., Comment: 7 pages, 5 figures
Published: 2018
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