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1. Measurement of the electric potential and the magnetic field in the shifted analysing plane of the KATRIN experiment

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Beisenkötter, J., Biassoni, M., Bieringer, B., Biondi, Y., Block, F., Bobien, S., Böttcher, M., Bornschein, B., Bornschein, L., Caldwell, T. S., Carminati, M., Chatrabhuti, A., Chilingaryan, S., Daniel, B. A., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Fengler, C., Fiorini, C., Formaggio, J. A., Forstner, C., Fränkle, F. M., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Hannen, V., Hasselmann, L., Haußmann, N., Helbing, K., Heyns, S., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Khosonthongkee, K., Köhler, C., Köllenberger, L., Kopmann, A., Kovač, N., Krause, H., La Cascio, L., Lasserre, T., Lauer, J., Le, T. L., Lebeda, O., Lehnert, B., Li, G., Lokhov, A., Machatschek, M., Mark, M., Marsteller, A., Martin, E. L., McMichael, K., Melzer, C., Mertens, S., Mohanty, S., Mostafa, J., Müller, K., Nava, A., Neumann, H., Niemes, S., Parno, D. S., Pavan, M., Pinsook, U., Poon, A. W. P., Poyato, J. M. L., Pozzi, S., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodenbeck, C., Röllig, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schrank, M., Schürmann, J., Schütz, A. K., Schwemmer, A., Schwenck, A., Šefčík, M., Siegmann, D., Simon, F., Spanier, F., Spreng, D., Sreethawong, W., Steidl, M., Štorek, J., Stribl, X., Sturm, M., Suwonjandee, N., Jerome, N. Tan, Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Weinheimer, C., Welte, S., Wendel, J., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadorozhny, S., and Zeller, G.

Subjects
Physics - Instrumentation and Detectors
Abstract

The projected sensitivity of the effective electron neutrino-mass measurement with the KATRIN experiment is below 0.3 eV (90 % CL) after five years of data acquisition. The sensitivity is affected by the increased rate of the background electrons from KATRIN's main spectrometer. A special shifted-analysing-plane (SAP) configuration was developed to reduce this background by a factor of two. The complex layout of electromagnetic fields in the SAP configuration requires a robust method of estimating these fields. We present in this paper a dedicated calibration measurement of the fields using conversion electrons of gaseous $^\mathrm{83m}$Kr, which enables the neutrino-mass measurements in the SAP configuration., Comment: 19 pages, 11 figures

Published
2024

2. Direct neutrino-mass measurement based on 259 days of KATRIN data

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Beisenkötter, J., Biassoni, M., Bieringer, B., Biondi, Y., Block, F., Bobien, S., Böttcher, M., Bornschein, B., Bornschein, L., Caldwell, T. S., Carminati, M., Chatrabhuti, A., Chilingaryan, S., Daniel, B. A., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Fengler, C., Fiorini, C., Formaggio, J. A., Forstner, C., Fränkle, F. M., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grohmann, S., Grössle, R., Gumbsheimer, R., Gutknecht, N., Hannen, V., Hasselmann, L., Haußmann, N., Helbing, K., Henke, H., Heyns, S., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Khosonthongkee, K., Kleifges, M., Klein, M., Kohpeiß, J., Köhler, C., Köllenberger, L., Kopmann, A., Kovač, N., Kovalík, A., Krause, H., La Cascio, L., Lasserre, T., Lauer, J., Le, T., Lebeda, O., Lehnert, B., Li, G., Lokhov, A., Machatschek, M., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Mertens, S., Mohanty, S., Mostafa, J., Müller, K., Nava, A., Neumann, H., Niemes, S., Onillon, A., Parno, D. S., Pavan, M., Pinsook, U., Poon, A. W. P., Poyato, J. M. Lopez, Pozzi, S., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schnurr, U., Schrank, M., Schürmann, J., Schütz, A., Schwemmer, A., Schwenck, A., Šefčík, M., Siegmann, D., Simon, F., Spanier, F., Spreng, D., Sreethawong, W., Steidl, M., Štorek, J., Stribl, X., Sturm, M., Suwonjandee, N., Jerome, N. Tan, Telle, H. H., Thorne, L. A., Thümmler, T., Tirolf, S., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Weinheimer, C., Welte, S., Wendel, J., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadorozhny, S., and Zeller, G.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The fact that neutrinos carry a non-vanishing rest mass is evidence of physics beyond the Standard Model of elementary particles. Their absolute mass bears important relevance from particle physics to cosmology. In this work, we report on the search for the effective electron antineutrino mass with the KATRIN experiment. KATRIN performs precision spectroscopy of the tritium $\beta$-decay close to the kinematic endpoint. Based on the first five neutrino-mass measurement campaigns, we derive a best-fit value of $m_\nu^{2} = {-0.14^{+0.13}_{-0.15}}~\mathrm{eV^2}$, resulting in an upper limit of $m_\nu < {0.45}~\mathrm{eV}$ at 90 % confidence level. With six times the statistics of previous data sets, amounting to 36 million electrons collected in 259 measurement days, a substantial reduction of the background level and improved systematic uncertainties, this result tightens KATRIN's previous bound by a factor of almost two., Comment: 61 pages, 20 figures, 2 tables

Published
2024

3. Search for keV-scale Sterile Neutrinos with first KATRIN Data

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., Chilingaryan, S., Choi, W., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Hannen, V., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kleifges, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., La Cascio, L., Lasserre, T., Le, T. L., Lebeda, O., Lehnert, B., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Mertens, S., Mostafa, J., Müller, K., Neumann, H., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schimpf, L., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schrank, M., Schwemmer, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Sturm, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wetter, M., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadoroghny, S., and Zeller, G.

Subjects
Nuclear Experiment
Abstract

In this work we present a keV-scale sterile-neutrino search with the first tritium data of the KATRIN experiment, acquired in the commissioning run in 2018. KATRIN performs a spectroscopic measurement of the tritium $\beta$-decay spectrum with the main goal of directly determining the effective electron anti-neutrino mass. During this commissioning phase a lower tritium activity facilitated the search for sterile neutrinos with a mass of up to $1.6\, \mathrm{keV}$. We do not find a signal and set an exclusion limit on the sterile-to-active mixing amplitude of down to $\sin^2\theta < 5\cdot10^{-4}$ ($95\,\%$ C.L.), improving current laboratory-based bounds in the sterile-neutrino mass range between 0.1 and $1.0\, \mathrm{keV}$.

Published
2022

4. Search for Lorentz-Invariance Violation with the first KATRIN data

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., Chilingaryan, S., Choi, W., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Hannen, V., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kleifges, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., La Cascio, L., Lasserre, T., Le, T. L., Lebeda, O., Lehnert, B., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Mertens, S., Mostafa, J., Müller, K., Neumann, H., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schimpf, L., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schrank, M., Schwemmer, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Sturm, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wetter, M., Wickles, J., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadoroghny, S., and Zeller, G.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Some extensions of the Standard Model of Particle Physics allow for Lorentz invariance and Charge-Parity-Time (CPT)-invariance violations. In the neutrino sector strong constraints have been set by neutrino-oscillation and time-of-flight experiments. However, some Lorentz-invariance-violating parameters are not accessible via these probes. In this work, we focus on the parameters $(a_{\text{of}}^{(3)})_{00}$, $(a_{\text{of}}^{(3)})_{10}$ and $(a_{\text{of}}^{(3)})_{11}$ which would manifest themselves in a non-isotropic beta-decaying source as a sidereal oscillation and an overall shift of the spectral endpoint. Based on the data of the first scientific run of the KATRIN experiment, we set the first limit on $\left|(a_{\text{of}}^{(3)})_{11}\right|$ of $< 3.7\cdot10^{-6}$ GeV at 90\% confidence level. Moreover, we derive new constraints on $(a_{\text{of}}^{(3)})_{00}$ and $(a_{\text{of}}^{(3)})_{10}$.

Published
2022
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5. KATRIN: Status and Prospects for the Neutrino Mass and Beyond

Author

Aker, M., Balzer, M., Batzler, D., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Biassoni, M., Bieringer, B., Block, F., Bobien, S., Bombelli, L., Bormann, D., Bornschein, B., Bornschein, L., Böttcher, M., Brofferio, C., Bruch, C., Brunst, T., Caldwell, T. S., Carminati, M., Carney, R. M. D., Chilingaryan, S., Choi, W., Cremonesi, O., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Fink, D., Fiorini, C., Formaggio, J. A., Forstner, C., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grande, A., Grössle, R., Gugiatti, M., Gumbsheimer, R., Hannen, V., Hartmann, J., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., King, P., Kleifges, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., Lasserre, T., La Cascio, L., Lebeda, O., Lechner, P., Lehnert, B., Le, T. L., Lokhov, A., Machatschek, M., Malcherek, E., Manfrin, D., Mark, M., Marsteller, A., Martin, E. L., Mazzola, E., Melzer, C., Mertens, S., Mostafa, J., Müller, K., Nava, A., Neumann, H., Niemes, S., Oelpmann, P., Onillon, A., Parno, D. S., Pavan, M., Pigliafreddo, A., Poon, A. W. P., Poyato, J. M. L., Pozzi, S., Priester, F., Puritscher, M., Radford, D. C., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R. W. J., Schäfer, P., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schneidewind, S., Schrank, M., Schütz, A. K., Schwemmer, A., Sedlak, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Spreng, D., Steidl, M., Sturm, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trigilio, P., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Voigt, P., Weinheimer, C., Weiss, E., Welte, S., Wendel, J., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wunderl, L., Wüstling, S., Wydra, J., Xu, W., Zadoroghny, S., and Zeller, G.

Subjects
Nuclear Experiment, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to measure a high-precision integral spectrum of the endpoint region of T2 beta decay, with the primary goal of probing the absolute mass scale of the neutrino. After a first tritium commissioning campaign in 2018, the experiment has been regularly running since 2019, and in its first two measurement campaigns has already achieved a sub-eV sensitivity. After 1000 days of data-taking, KATRIN's design sensitivity is 0.2 eV at the 90% confidence level. In this white paper we describe the current status of KATRIN; explore prospects for measuring the neutrino mass and other physics observables, including sterile neutrinos and other beyond-Standard-Model hypotheses; and discuss research-and-development projects that may further improve the KATRIN sensitivity., Comment: Contribution to Snowmass 2021. 70 pages excluding references; 35 figures. Author list updated June 2023

Published
2022
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6. New Constraint on the Local Relic Neutrino Background Overdensity with the First KATRIN Data Runs

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., Chilingaryan, S., Choi, W., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Hannen, V., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, F., Kellerer, J., Kleifges, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., La Cascio, L., Lasserre, T., Le, T. L., Lebeda, O., Lehnert, B., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Mertens, S., Mostafa, J., Müller, K., Neumann, H., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schimpf, L., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schrank, M., Schwemmer, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Sturm, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wetter, M., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadoroghny, S., and Zeller, G.

Subjects
Nuclear Experiment, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Experiment
Abstract

We report on the direct cosmic relic neutrino background search from the first two science runs of the KATRIN experiment in 2019. Beta-decay electrons from a high-purity molecular tritium gas source are analyzed by a high-resolution MAC-E filter around the kinematic endpoint at 18.57 keV. The analysis is sensitive to a local relic neutrino overdensity of 9.7e10 (1.1e11) at a 90% (95%) confidence level. A fit of the integrated electron spectrum over a narrow interval around the kinematic endpoint accounting for relic neutrino captures in the Tritium source reveals no significant overdensity. This work improves the results obtained by the previous kinematic neutrino mass experiments at Los Alamos and Troitsk. We furthermore update the projected final sensitivity of the KATRIN experiment to <1e10 at 90% confidence level, by relying on updated operational conditions., Comment: 7 pages, 7 figures

Published
2022
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7. Improved eV-scale Sterile-Neutrino Constraints from the Second KATRIN Measurement Campaign

Author

Aker, M., Batzler, D., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., Chilingaryan, S., Choi, W., Debowski, K., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gavin, A. S., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Hannen, V., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kleifges, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., La Cascio, L., Lasserre, T., Le, T. L., Lebeda, O., Lehnert, B., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Mertens, S., Mostafa, J., Müller, K., Neumann, H., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ráliš, J., Ramachandran, S., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Salomon, R., Schäfer, P., Schimpf, L., Schlösser, M., Schlösser, K., Schlüter, L., Schneidewind, S., Schrank, M., Schwemmer, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Sturm, M., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wetter, M., Wiesinger, C., Wilkerson, J. F., Wolf, J., Wüstling, S., Wydra, J., Xu, W., Zadoroghny, S., and Zeller, G.

Subjects
High Energy Physics - Experiment
Abstract

We present the results of the light sterile neutrino search from the second KATRIN measurement campaign in 2019. Approaching nominal activity, $3.76 \times 10^6$ tritium $\beta$-electrons are analyzed in an energy window extending down to $40\,$eV below the tritium endpoint at $E_0 = 18.57\,$keV. We consider the $3\nu+1$ framework with three active and one sterile neutrino flavor. The analysis is sensitive to a fourth mass eigenstate $m_4^2\lesssim1600\,$eV$^2$ and active-to-sterile mixing $|U_{e4}|^2 \gtrsim 6 \times 10^{-3}$. As no sterile-neutrino signal was observed, we provide improved exclusion contours on $m_4^2$ and $|U_{e4}|^2$ at $95\,$% C.L. Our results supersede the limits from the Mainz and Troitsk experiments. Furthermore, we are able to exclude the large $\Delta m_{41}^2$ solutions of the reactor antineutrino and gallium anomalies to a great extent. The latter has recently been reaffirmed by the BEST collaboration and could be explained by a sterile neutrino with large mixing. While the remaining solutions at small $\Delta m_{41}^2$ are mostly excluded by short-baseline reactor experiments, KATRIN is the only ongoing laboratory experiment to be sensitive to relevant solutions at large $\Delta m_{41}^2$ through a robust spectral shape analysis., Comment: 14 pages, 8 figures, 2 tables

Published
2022
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8. Direct neutrino-mass measurement with sub-electronvolt sensitivity

Author

Aker, M, Beglarian, A, Behrens, J, Berlev, A, Besserer, U, Bieringer, B, Block, F, Bobien, S, Boettcher, M, Bornschein, B, Bornschein, L, Brunst, T, Caldwell, TS, Carney, RMD, La Cascio, L, Chilingaryan, S, Choi, W, Debowski, K, Deffert, M, Descher, M, Barrero, D Diaz, Doe, PJ, Dragoun, O, Drexlin, G, Eitel, K, Ellinger, E, Engel, R, Enomoto, S, Felden, A, Formaggio, JA, Fraenkle, FM, Franklin, GB, Friedel, F, Fulst, A, Gauda, K, Gil, W, Glueck, F, Groessle, R, Gumbsheimer, R, Gupta, V, Hoehn, T, Hannen, V, Haussmann, N, Helbing, K, Hickford, S, Hiller, R, Hillesheimer, D, Hinz, D, Houdy, T, Huber, A, Jansen, A, Karl, C, Kellerer, F, Kellerer, J, Kleifges, M, Klein, M, Koehler, C, Koellenberger, L, Kopmann, A, Korzeczek, M, Kovalik, A, Krasch, B, Krause, H, Kunka, N, Lasserre, T, Le, TL, Lebeda, O, Lehnert, B, Lokhov, A, Machatschek, M, Malcherek, E, Mark, M, Marsteller, A, Martin, EL, Melzer, C, Menshikov, A, Mertens, S, Mostafa, J, Mueller, K, Neumann, H, Niemes, S, Oelpmann, P, Parno, DS, Poon, AWP, Poyato, JML, Priester, F, Ramachandran, S, Robertson, RGH, Rodejohann, W, Roellig, M, Roettele, C, Rodenbeck, C, Rysavy, M, Sack, R, Saenz, A, Schaefer, P, Pollithy, A Schaller Nee, Schimpf, L, Schloesser, K, and Schloesser, M

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Mathematical Sciences, Fluids & Plasmas, Mathematical sciences, Physical sciences
Abstract

Since the discovery of neutrino oscillations, we know that neutrinos have non-zero mass. However, the absolute neutrino-mass scale remains unknown. Here we report the upper limits on effective electron anti-neutrino mass, mν, from the second physics run of the Karlsruhe Tritium Neutrino experiment. In this experiment, mν is probed via a high-precision measurement of the tritium β-decay spectrum close to its endpoint. This method is independent of any cosmological model and does not rely on assumptions whether the neutrino is a Dirac or Majorana particle. By increasing the source activity and reducing the background with respect to the first physics campaign, we reached a sensitivity on mν of 0.7 eV c–2 at a 90% confidence level (CL). The best fit to the spectral data yields mν2 = (0.26 ± 0.34) eV2 c–4, resulting in an upper limit of mν < 0.9 eV c–2 at 90% CL. By combining this result with the first neutrino-mass campaign, we find an upper limit of mν < 0.8 eV c–2 at 90% CL.

Published
2022

9. First direct neutrino-mass measurement with sub-eV sensitivity

Author

Aker, M., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., La Cascio, L., Chilingaryan, S., Choi, W., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gil, W., Glück, F., Grössle, R., Gumbsheimer, R., Gupta, V., Höhn, T., Hannen, V., Haußmann, N., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, F., Kellerer, J., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., Kunka, N., Lasserre, T., Le, T. L., Lebeda, O., Lehnert, B., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Melzer, C., Menshikov, A., Mertens, S., Mostafa, J., Müller, K., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Röllig, M., Röttele, C., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Ryšavý, M., Sack, R., Saenz, A., Schäfer, P., Schaller, A., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schneidewind, S., Schrank, M., Schulz, B., Schwemmer, A., Šefčík, M., Sibille, V., Siegmann, D., Slezák, M., Steidl, M., Sturm, M., Sun, M., Tcherniakhovski, D., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., Xu, W., Yen, Y. -R., Zadoroghny, S., and Zeller, G.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

We report the results of the second measurement campaign of the Karlsruhe Tritium Neutrino (KATRIN) experiment. KATRIN probes the effective electron anti-neutrino mass, $m_{\nu}$, via a high-precision measurement of the tritium $\beta$-decay spectrum close to its endpoint at $18.6\,\mathrm{keV}$. In the second physics run presented here, the source activity was increased by a factor of 3.8 and the background was reduced by $25\,\%$ with respect to the first campaign. A sensitivity on $m_{\nu}$ of $0.7\,\mathrm{eV/c^2}$ at $90\,\%$ confidence level (CL) was reached. This is the first sub-eV sensitivity from a direct neutrino-mass experiment. The best fit to the spectral data yields $m_{\nu}^2 = (0.26\pm0.34)\,\mathrm{eV^4/c^4}$, resulting in an upper limit of $m_{\nu}<0.9\,\mathrm{eV/c^2}$ ($90\,\%$ CL). By combining this result with the first neutrino mass campaign, we find an upper limit of $m_{\nu}<0.8\,\mathrm{eV/c^2}$ ($90\,\%$ CL)., Comment: 19 pages, 10 figures, 5 tables

Published
2021

10. Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment

Author

Aker, M., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Bieringer, B., Block, F., Bornschein, B., Bornschein, L., Böttcher, M., Brunst, T., Caldwell, T. S., Carney, R. M. D., Chilingaryan, S., Choi, W., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Edzards, F., Eitel, K., Ellinger, E., Miniawy, A. El, Engel, R., Enomoto, S., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Friedel, F., Fulst, A., Gauda, K., Gil, W., Glück, F., Groh, S., Grössle, R., Gumbsheimer, R., Hannen, V., Haußmann, N., Heizmann, F., Helbing, K., Hickford, S., Hiller, R., Hillesheimer, D., Hinz, D., Höhn, T., Houdy, T., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kleesiek, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., Kunka, N., Lasserre, T., La Cascio, L., Lebeda, O., Lehnert, B., Le, T. L., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Meier, M., Melzer, C., Menshikov, A., Mertens, S., Mostafa, J., Müller, K., Niemes, S., Oelpmann, P., Parno, D. S., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ranitzsch, P. C. -O., Robertson, R. G. H., Rodejohann, W., Rodenbeck, C., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schäfer, P., Schaller, A., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schneidewind, S., Schrank, M., Schulz, B., Schwachtgen, C., Šefčík, M., Seitz-Moskaliuk, H., Sibille, V., Siegmann, D., Slezák, M., Steidl, M., Sturm, M., Sun, M., Tcherniakhovski, D., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Urban, K., Valerius, K., Vénos, D., Hernández, A. P. Vizcaya, Weinheimer, C., Welte, S., Wendel, J., Wilkerson, J. F., Wolf, J., Wüstling, S., Xu, W., Yen, Y. -R., Zadoroghny, S., and Zeller, G.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium $\beta$-decay endpoint region with a sensitivity on $m_\nu$ of 0.2$\,$eV/c$^2$ (90% CL). For this purpose, the $\beta$-electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6$\,$keV. A dominant systematic effect of the response of the experimental setup is the energy loss of $\beta$-electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the \linebreak energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes; the latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95% T$_2$ gas mixture at 30$\,$K, as used in the first KATRIN neutrino mass analyses, as well as a D$_2$ gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of $\sigma(m_\nu^2)<10^{-2}\,\mathrm{eV}^2$ [arXiv:2101.05253] in the KATRIN neutrino-mass measurement to a subdominant level., Comment: 12 figures, 18 pages; to be submitted to EPJ C

Published
2021
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11. Suppression of Penning discharges between the KATRIN spectrometers

Author

Aker, M., Altenmüller, K., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Blaum, K., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Bouquet, H., Brunst, T., Caldwell, T. S., Chilingaryan, S., Choi, W., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Eversheim, D., Fedkevych, M., Felden, A., Formaggio, J. A., Fränkle, F., Franklin, G. B., Frankrone, H., Friedel, F., Fulst, A., Gauda, K., Gil, W., Glück, F., Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Hartmann, J., Haußmann, N., Heizmann, F., Heizmann, J., Helbing, K., Hickford, S., Hillesheimer, D., Hinz, D., Höhn, T., Holzapfel, B., Holzmann, S., Houdy, T., Jansen, A., Karl, C., Kellerer, J., Kernert, N., Kippenbrock, L., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., Kuffner, B., Kunka, N., Lasserre, T., La Cascio, L., Lebeda, O., Lehnert, B., Letnev, J., Leven, F., Le, T. L., Lichter, S., Lokhov, A., Machatschek, M., Malcherek, E., Marsteller, A., Martin, E. L., Melzer, C., Menshikov, A., Mertens, S., Monreal, B., Müller, K., Naumann, U., Neumann, H., Niemes, S., Noe, M., Ortjohann, H. -W., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ranitzsch, P. C. -O., Rest, O., Rinderspacher, R., Robertson, R. G. H., Rodenbeck, C., Rohr, P., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schäfer, P., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schrank, M., Schulz, B., Seitz-Moskaliuk, H., Seller, W., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Steven, M., Sturm, M., Suesser, M., Sun, 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., Xu, W., Yen, Y. -R., Zadoroghny, S., and Zeller, G.

Subjects
Physics - Instrumentation and Detectors
Abstract

The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to determine the effective electron (anti)neutrino mass with a sensitivity of $0.2\textrm{ eV/c}^2$ (90$\%$ C.L.) by precisely measuring the endpoint region of the tritium $\beta$-decay spectrum. It uses a tandem of electrostatic spectrometers working as MAC-E (magnetic adiabatic collimation combined with an electrostatic) filters. In the space between the pre-spectrometer and the main spectrometer, an unavoidable Penning trap is created when the superconducting magnet between the two spectrometers, biased at their respective nominal potentials, is energized. The electrons accumulated in this trap can lead to discharges, which create additional background electrons and endanger the spectrometer and detector section downstream. To counteract this problem, "electron catchers" were installed in the beamline inside the magnet bore between the two spectrometers. These catchers can be moved across the magnetic-flux tube and intercept on a sub-ms time scale the stored electrons along their magnetron motion paths. In this paper, we report on the design and the successful commissioning of the electron catchers and present results on their efficiency in reducing the experimental background., Comment: - 12 pages, 14 figures, LaTeX; typos corrected, references added; precised a few arguments, added additional discussions, results unchanged

Published
2019
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12. 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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13. First operation of the KATRIN experiment with tritium

Author

Aker, M., Altenmüller, K., Arenz, M., Baek, W. -J., Barrett, J., Beglarian, A., Behrens, J., Berlev, A., Besserer, U., Blaum, K., Block, F., Bobien, S., Bornschein, B., Bornschein, L., Bouquet, H., Brunst, T., Caldwell, T. S., Chilingaryan, S., Choi, W., Debowski, K., Deffert, M., Descher, M., Barrero, D. Díaz, Doe, P. J., Dragoun, O., Drexlin, G., Dyba, S., Edzards, F., Eitel, K., Ellinger, E., Engel, R., Enomoto, S., Eversheim, D., Fedkevych, M., Felden, A., Formaggio, J. A., Fränkle, F. M., Franklin, G. B., Frankrone, H., Friedel, F., Fuchs, D., Fulst, A., Gauda, K., Gil, W., Glück, F., Grohmann, S., Grössle, R., Gumbsheimer, R., Hackenjos, M., Hannen, V., Hartmann, J., Haußmann, N., Minh, M. Ha, Heizmann, F., Heizmann, J., Helbing, K., Hickford, S., Hillesheimer, D., Hinz, D., Höhn, T., Holzapfel, B., Holzmann, S., Houdy, T., Howe, M. A., Huber, A., Jansen, A., Karl, C., Kellerer, J., Kernert, N., Kippenbrock, L., Kleesiek, M., Klein, M., Köhler, C., Köllenberger, L., Kopmann, A., Korzeczek, M., Kovalík, A., Krasch, B., Krause, H., Kuffner, B., Kunka, N., Lasserre, T., La Cascio, L., Lebeda, O., Lebert, M., Lehnert, B., Letnev, J., Leven, F., Le, T. L., Lichter, S., Lokhov, A., Machatschek, M., Malcherek, E., Mark, M., Marsteller, A., Martin, E. L., Megas, F., Melzer, C., Menshikov, A., Mertens, S., Meier, M., Mirz, S., Monreal, B., Guzmán, P. I. Morales, Müller, K., Naumann, U., Neumann, H., Niemes, S., Noe, M., Off, A., Ortjohann, H. -W., Osipowicz, A., Otten, E., Parno, D. S., Pollithy, A., Poon, A. W. P., Poyato, J. M. L., Priester, F., Ranitzsch, P. C. -O., Rest, O., Rinderspacher, R., Robertson, R. G. H., Rodenbeck, C., Rohr, P., Röllig, M., Röttele, C., Ryšavý, M., Sack, R., Saenz, A., Schäfer, P., Schimpf, L., Schlösser, K., Schlösser, M., Schlüter, L., Schrank, M., Schulz, B., Seitz-Moskaliuk, H., Seller, W., Sibille, V., Siegmann, D., Slezák, M., Spanier, F., Steidl, M., Steven, M., Sturm, M., Suesser, M., Sun, M., Tcherniakhovski, D., Telle, H. H., Thorne, L. A., Thümmler, T., Titov, N., Tkachev, I., Trost, N., Urban, K., 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., Xu, W., Yen, Y. -R., Zadorozhny, S., and Zeller, G.

Subjects
Physics - Instrumentation and Detectors, Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Experiment, Nuclear Experiment
Abstract

The determination of the neutrino mass is one of the major challenges in astroparticle physics today. Direct neutrino mass experiments, based solely on the kinematics of beta-decay, provide a largely model-independent probe to the neutrino mass scale. The Karlsruhe Tritium Neutrino (KATRIN) experiment is designed to directly measure the effective electron antineutrino mass with a sensitivity of 0.2 eV 90% CL. In this work we report on the first operation of KATRIN with tritium which took place in 2018. During this commissioning phase of the tritium circulation system, excellent agreement of the theoretical prediction with the recorded spectra was found and stable conditions over a time period of 13 days could be established. These results are an essential prerequisite for the subsequent neutrino mass measurements with KATRIN in 2019.

Published
2019
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14. Relaxation of curvature induced elastic stress by the Asaro-Tiller-Grinfeld instability

Author

Köhler, C., Backofen, R., and Voigt, A.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

A two-dimensional crystal on the surface of a sphere experiences elastic stress due to the incompatibility of the crystal axes and the curvature. A common mechanism to relax elastic stress is the Asaro-Tiller-Grinfeld (ATG) instability. With a combined numerical and analytical approach we demonstrate, that also curvature induced stress in surface crystals can be relaxed by the long wave length ATG instability. The numerical results are obtained using a surface phase-field crystal (PFC) model, from which we determine the characteristic wave numbers of the ATG instability for various surface coverages corresponding to different curvature induced compressions. The results are compared with an analytic expression for the characteristic wave number, obtained from a continuum approach which accounts for hexagonal crystals and intrinsic PFC symmetries. We find our numerical results in accordance with the analytical predictions., Comment: 6 pages, 5 figures

Published
2015
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15. Boosting terahertz generation in laser-field ionized gases using a sawtooth wave shape

Author

Martínez, P. González de Alaiza, Babushkin, I., Bergé, L., Skupin, S., Cabrera-Granado, E., Köhler, C., Morgner, U., Husakou, A., and Herrmann, J.

Subjects
Physics - Optics, Physics - Plasma Physics
Abstract

Broadband ultrashort terahertz (THz) pulses can be produced using plasma generation in a noble gas ionized by femtosecond two-color pulses. Here we demonstrate that, by using multiple-frequency laser pulses, one can obtain a waveform which optimizes the free electron trajectories in such a way that they reach the highest velocity at the electric field extrema. This allows to increase the THz conversion efficiency to the percent level, an unprecedented performance for THz generation in gases. Besides the analytical study of THz generation using a local current model, we perform comprehensive 3D simulations accounting for propagation effects which confirm this prediction. Our results show that THz conversion via tunnel ionization can be greatly improved with well-designed multicolor pulses.

Published
2014
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16. Large resistivity change and phase transition in LiMnAs

Author

Beleanu, A., Kiss, J., Kreiner, G., Köhler, C., Müchler, L., Schnelle, W., Burkhardt, U., Chadov, S., Medvediev, S., Ebke, D., Cordier, G., Albert, B., Hoser, A., Bernardi, F., Larkin, T. I., Pröpper, D., Boris, A. V., Keimer, B., and Felser, C.

Subjects
Condensed Matter - Materials Science
Abstract

Antiferromagnetic semiconductors are new alternative materials for spintronic applications and spin valves. In this work, we report a detailed investigation of two antiferromagnetic semiconductors AMnAs (A = Li, LaO), which are isostructural to the well-known LiFeAs and LaOFeAs superconductors. Here we present a comparison between the structural, magnetic, and electronic properties of LiMnAs, LaOMnAs and related materials. Interestingly, both LiMnAs and LaOMnAs show a variation in resistivity with more than five orders of magnitude, making them particularly suitable for use in future electronic devices. From neutron and X-ray diffraction measurements on LiMnAs we have observed a magnetic phase transition corresponding to the Neel temperature of 373.8 K, and a structural transition from the tetragonal to the cubic phase at 768 K. These experimental results are supported by density functional theory (DFT) calculations.

Published
2013

18. Tailoring THz radiation by controlling tunnel photoionization events in gases

Author

Babushkin, I., Skupin, S., Husakou, A., Köhler, C., Cabrera-Granado, E., Bergé, L., and Herrmann, J.

Subjects
Physics - Optics
Abstract

Applications ranging from nonlinear terahertz spectroscopy to remote sensing require broadband and intense THz radiation which can be generated by focusing two-color laser pulses into a gas. In this setup, THz radiation originates from the buildup of the electron density in sharp steps of attosecond duration due to tunnel ionization, and subsequent acceleration of free electrons in the laser field. We show that the spectral shape of the THz pulses generated by this mechanism is determined by superposition of contributions from individual ionization events. This provides a straightforward analogy with linear diffraction theory, where the ionization events play the role of slits in a grating. This analogy offers simple explanations for recent experimental observations and opens new avenues for THz pulse shaping based on temporal control of the ionization events. We illustrate this novel technique by tailoring the spectral width and position of the resulting radiation using multi-color pump pulses., Comment: 9 pages, 5 figures

Published
2011
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19. Ultrafast spatio-temporal dynamics of terahertz generation by ionizing two-color femtosecond pulses in gases

Author

Babushkin, I., Kuehn, W., Koehler, C., Skupin, S., Berge, L., Reimann, K., Woerner, M., Herrmann, J., and Elsaesser, T.

Subjects
Physics - Optics
Abstract

We present a combined theoretical and experimental study of spatio-temporal propagation effects in terahertz (THz) generation in gases using two-color ionizing laser pulses. The observed strong broadening of the THz spectra with increasing gas pressure reveals the prominent role of spatio-temporal reshaping and of a plasma-induced blue-shift of the pump pulses in the generation process. Results obtained from (3+1)-dimensional simulations are in good agreement with experimental findings and clarify the mechanisms responsible for THz emission.

Published
2010
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20. Compression of ultrashort UV pulses in a self-defocusing gas

Author

Berge, L., Koehler, C., and Skupin, S.

Subjects
Physics - Optics, Physics - Plasma Physics
Abstract

Compression of UV femtosecond laser pulses focused into a gas cell filled with xenon is reported numerically. With a large negative Kerr index and normal dispersion, xenon promotes temporal modulational instability (MI) which can be monitored to shorten ~ 100 fs pulses to robust, singly-peaked waveforms exhibiting a fourfold compression factor. Combining standard MI theory with a variational approach allows us to predict the beam parameters suitable for efficient compression. At powers < 30 MW, nonlinear dispersion is shown to shift the pulse temporal profile to the rear zone., Comment: 4 pages, 4 figures

Published
2009
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22. Probing unexplored territories with MUSE: a second generation instrument for the VLT

Author

Bacon, R., Bauer, S., Boehm, P., Boudon, D., Brau-Nogue, S., Caillier, P., Capoani, L., Carollo, C. M., Champavert, N., Contini, T., Daguise, E., Dalle, D., Delabre, B., Devriendt, J., Dreizler, S., Dubois, J., Dupieux, M., Dupin, J. P., Emsellem, E., Ferruit, P., Franx, M., Gallou, G., Gerssen, J., Guiderdoni, B., Hahn, T., Hofmann, D., Jarno, A., Kelz, A., Koehler, C., Kollatschny, W., Kosmalski, J., Laurent, F., Lilly, S. J., Lizon, J., Loupias, M., Lynn, S., Manescau, A., McDermid, R. M., Monstein, C., Nicklas, H., Pares, L., Pasquini, L., Pecontal-Rousset, A., Pecontal, E., Pello, R., Petit, C., Picat, J. -P., Popow, E., Quirrenbach, A., Reiss, R., Renault, E., Roth, M., Schaye, J., Soucail, G., Steinmetz, M., Stroebele, S., Stuik, R., Weilbacher, P., Wozniak, H., and de Zeeuw, P. T.

Subjects
Astrophysics
Abstract

The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph under preliminary design study. MUSE has a field of 1x1 arcmin**2 sampled at 0.2x0.2 arcsec**2 and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The simultaneous spectral range is 465-930 nm, at a resolution of R~3000. MUSE couples the discovery potential of a large imaging device to the measuring capabilities of a high-quality spectrograph, while taking advantage of the increased spatial resolution provided by adaptive optics. This makes MUSE a unique and tremendously powerful instrument for discovering and characterizing objects that lie beyond the reach of even the deepest imaging surveys. MUSE has also a high spatial resolution mode with 7.5x7.5 arcsec**2 field of view sampled at 25 milli-arcsec. In this mode MUSE should be able to obtain diffraction limited data-cubes in the 600-930 nm wavelength range. Although the MUSE design has been optimized for the study of galaxy formation and evolution, it has a wide range of possible applications; e.g. monitoring of outer planets atmosphere, environment of young stellar objects, super massive black holes and active nuclei in nearby galaxies or massive spectroscopic surveys of stellar fields in the Milky Way and nearby galaxies., Comment: Astronomical Telescopes and Instrumentation, SPIE 6265 Orlando 24-31May 2006 9 pages

Published
2006
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23. On the optimum spacing of stereoscopic imaging atmospheric Cherenkov telescopes

Author

HEGRA Collaboration, Hofmann, W., Hermann, G., Konopelko, A., Krawczynski, H., Koehler, C., and Puehlhofer, G.

Subjects
Astrophysics
Abstract

For stereoscopic systems of imaging atmospheric Cherenkov telescopes (IACTs), a key parameter to optimize the sensitivity for VHE gamma-ray point sources is the intertelescope spacing. Using pairs of telescopes of the HEGRA IACT system, the sensitivity of two-telescope stereo IACT systems is studied as a function of the telescope spacing, ranging from 70 m to 140 m. Data taken during the 1997 outburst of Mrk 501 are used to evaluate both the detection rates before cuts, and the sensitivity for weak signals after cuts to optimize the significance of signals. Detection rates decrease by about 1/3 between the minimum and maximum spacing. The significance of signals is essentially independent of distance, in the range investigated., Comment: 9 Pages, 3 Figures, Latex

Published
1999

24. Locating TeV Gamma-Ray Sources with Sub-Arcminute Precision: the Pointing Calibration of the HEGRA System of Imaging Atmospheric Cherenkov Telescopes

Author

Puehlhofer, G., Daum, A., Hermann, G., Hess, M., Hofmann, W., Koehler, C., and Panter, M.

Subjects
Astrophysics
Abstract

Stereoscopic viewing of TeV gamma-ray air showers with systems of Imaging Atmospheric Cherenkov Telescopes (IACTs) allows to reconstruct the origin of individual primary particles with an accuracy of 0.1 degree or better. The shower impact point can be determined within 15 meters. To actually achieve this resolution, the pointing of the telescopes of an IACT system needs to be controlled with high precision. For the HEGRA IACT system, a procedure to calibrate telescope pointing was established, using bright stars distributed over the sky as references. On the basis of these measurements, one determines parameters of a correction function which is valid for the complete hemisphere. After correction a pointing accuracy of 0.01 degree is achieved., Comment: 14 pages, 7 postscript figures, Latex2e; accepted in Astroparticle Physics

Published
1998

25. Characteristics of the Multi-Telescope Coincidence Trigger of the HEGRA IACT System

Author

Bulian, N., Daum, A., Hermann, G., Hess, M., Hofmann, W., Lampeitl, H., Puehlhofer, G., Koehler, C., Panter, M., Stein, M., Boerst, G., Rauterberg, G., Samorski, M., Sauerland, C., and Stamm, W.

Subjects
Astrophysics
Abstract

The HEGRA--collaboration is operating a system of imaging atmospheric Cherenkov telescopes to search for sources of TeV-gamma-rays. Air showers are observed in stereoscopic mode with several telescopes simultaneously. To trigger the telescope system a versatile two-level trigger scheme has been implemented, which allows a significant reduction of the energy threshold with respect to single telescopes. The technical implementation of this trigger scheme and the performance of the trigger system are described. Results include the dependence of single- and multi-telescope trigger rates on the trigger thresholds, on the orientation of the telescopes, and on the type of the primary particle., Comment: 17 Pages, 10 figures, Latex

Published
1997
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26. Calibration of the Sensitivity of Imaging Atmospheric Cherenkov Telescopes using a Reference Light Source

Author

Frass, A., Koehler, C., Hermann, G., Hess, M., and Hofmann, W.

Subjects
Astrophysics
Abstract

The sensitivity of an Imaging Atmospheric Cherenkov telescope is calibrated by shining, from a distant pulsed monochromatic light source, a defined photon flux onto the mirror. The light pulse is captured and reconstructed by the telescope in an identical fashion as real Cherenkov light. The intensity of the calibration light pulse is monitored via a calibrated sensor at the telescope; in order to account for the lower sensitivity of this sensor compared to the Cherenkov telescope, an attenuator is inserted in the light source between the measurements with the calibrated sensor, and with the telescope. The resulting telescope sensitivities have errors of 10%, and compare well with other estimates of the sensitivity., Comment: 14 Pages, 5 figures, Latex, uses epsf

Published
1997
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27. Triggering of Imaging Air Cherenkov Telescopes: PMT trigger rates due to night-sky photons

Author

Hermann, G., Köhler, C., Kutter, T., and Hofmann, W.

Subjects
Astrophysics, High Energy Physics - Experiment, Nuclear Experiment
Abstract

Imaging air Cherenkov telescopes are usually triggered on a coincidence of two or sometimes more pixels, with discriminator thresholds in excess of 20 photoelectrons applied for each pixel. These thresholds required to suppress night-sky background are significantly higher than expected on the basis of a Poisson distribution in the number of night-sky photoelectrons generated during the characteristic signal integration time. We studied noise trigger rates under controlled conditions using an artificial background light source. Large tails in the PMT amplitude response to single photoelectrons are identified as a dominant contribution to noise triggers. The rate of such events is very sensitive to PMT operating parameters., Comment: 19 pages, latex,epsf, 7 figures appended as uuencoded file, submitted to Journal of Physics G

Published
1995

30. Treatment of micropollutants in wastewater: Balancing effectiveness, costs and implications

Author

Pistocchi, A., primary, Andersen, H.R., additional, Bertanza, G., additional, Brander, A., additional, Choubert, J.M., additional, Cimbritz, M., additional, Drewes, J.E., additional, Koehler, C., additional, Krampe, J., additional, Launay, M., additional, Nielsen, P.H., additional, Obermaier, N., additional, Stanev, S., additional, and Thornberg, D., additional

Published
2022
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31. New Science Opportunities Offered by MUSE

Author

Bacon, R., Bauer, S., Brau-Nogué, S., Caillier, P., Capoani, L., Carollo, M., Contini, T., Daguisé, E., Delabre, B., Dreizler, S., Dubois, J. P., Dupieux, M., Dupin, J., Emsellem, E., Ferruit, P., Francois, M., Franx, M., Gallou, G., Gerssen, J., Guiderdoni, B., Hansali, G., Hofmann, D., Jarno, A., Kelz, A., Koehler, C., Kollatschny, W., Kosmalski, J., Laurent, F., Lilly, S., Lizon, J., Loupias, M., Monstein, C., Moultaka, J., Nicklas, H., Parés, L., Pasquini, L., Pecontal, A., Pello, R., Petit, C., Manescau, A., Reiss, R., Remillieux, A., Renault, E., Roth, M., Schaye, J., Steinmetz, M., Ströbele, S., Stuik, R., Weilbacher, P., Wisotzki, L., Wozniak, H., Burton, W. B., editor, Christensen, Lars Lindberg, editor, and Moorwood, Alan, editor

Published
2009
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32. MUSE: A Second-Generation Integral-Field Spectrograph for the VLT

Author

McDermid, R. M., Bacon, R., Bauer, S., Boehm, P., Boudon, D., Brau-Nogué, S., Caillier, P., Capoani, L., Carollo, C. M., Champavert, N., Contini, T., Daguisé, E., Delabre, B., Devriendt, J., Dreizler, S., Dubois, J., Dupieux, M., Dupin, J. P., Emsellem, E., Ferruit, P., Franx, M., Gallou, G., Gerssen, J., Guiderdoni, B., Hahn, T., Hofmann, D., Jarno, A., Kelz, A., Koehler, C., Kollatschny, W., Kosmalski, J., Laurent, F., Lilly, S. J., Lizon, J. L., Loupias, M., Manescau, A., Monstein, C., Nicklas, H., Parès, L., Pasquini, L., Pécontal-Rousset, A., Pécontal, E., Pello, R., Petit, C., Picat, J.-P., Popow, E., Quirrenbach, A., Reiss, R., Renault, E., Roth, M., Schaye, J., Soucail, G., Steinmetz, M., Stroebele, S., Stuik, R., Weilbacher, P., Wisotzki, L., Wozniak, H., de Zeeuw, P. T., Leibundgut, Bruno, editor, Kaufer, Andreas, editor, and Kerber, Florian, editor

Published
2008
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45. Anwendunggen

Author

Debold, P., Eysenbach, G., Dickehut, B., Ellsässer, K.-H., Hertwig, U., Zimpelmann, B., Köhler, C. O., and Schaefer, O. P., editor

Published
1995
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49. Rocket Observation of Sub‐Relativistic Electrons in the Quiet Dayside Auroral Ionosphere

Author

Namekawa, T., primary, Mitani, T., additional, Asamura, K., additional, Miyoshi, Y., additional, Hosokawa, K., additional, Ogawa, Y., additional, Saito, S., additional, Hori, T., additional, Sugo, S., additional, Kawashima, O., additional, Kasahara, S., additional, Nomura, R., additional, Yagi, N., additional, Fukizawa, M., additional, Sakanoi, T., additional, Saito, Y., additional, Matsuoka, A., additional, Shinohara, I., additional, Fedorenko, Y., additional, Nikitenko, A., additional, and Koehler, C., additional

Published
2021
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