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1. Directional Sensitivity of the NEWSdm Experiment to Cosmic Ray Boosted Dark Matter

Author: Agafonova, N. Y., Alexandrov, A., Anokhina, A. M., Asada, T., Ashikhmin, V. V, Boccia, V., Centanni, D., Chernyavskii, M. M., D'Ambrosio, N., De Lellis, G., Di Crescenzo, A., Dowdy, Y. C., Dmitrievski, S., Enikeev, R. I., Galati, G., Galkin, V. I., Golovatiuk, A., Gorbunov, S. A., Gornushkin, Y., Guler, A. M., Gulyaeva, V. V., Iuliano, A., Khalikov, E. V., Kim, S. H., Konovalova, N. S., Krasilnikova, Y. O., Lauria, A., Lee, K. Y., Loschiavo, V. P., Managadze, A. K., Miloi, A., Montesi, M. C., Naka, T., Okateva, N. M., Park, B. D, Podgrudkov, D. A., Polukhina, N. G., Roganova, T. M., Rosa, G., Samoilov, M. A., Sadykov, Z. T., Saeki, K., Sato, O., Shakiryanova, I. R., Shchedrina, T. V., Shiraishi, T., Sohn, J. Y., Sotnikov, A., Starkov, N. I., Starkova, E. N., Strekalina, D. M., Tioukov, V., Ursov, E. D., Ustyuzhanin, A., Vasina, S., Voronkov, R. A., and Yoon, C. S.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present a study of a directional search for Dark Matter boosted forward when scattered by cosmic-ray nuclei, using a module of the NEWSdm experiment. The boosted Dark Matter flux at the edge of the Earth's atmosphere is expected to be pointing to the Galactic Center, with a flux 15 to 20 times larger than in the transverse direction. The module of the NEWSdm experiment consists of a 10 kg stack of Nano Imaging Trackers, i.e.~newly developed nuclear emulsions with AgBr crystal sizes down to a few tens of nanometers. The module is installed on an equatorial telescope. The relatively long recoil tracks induced by boosted Dark Matter, combined with the nanometric granularity of the emulsion, result in an extremely low background. This makes an installation at the INFN Gran Sasso laboratory, both on the surface and underground, viable. A comparison between the two locations is made. The angular distribution of nuclear recoils induced by boosted Dark Matter in the emulsion films at the surface laboratory is expected to show an excess with a factor of 3.5 in the direction of the Galactic Center. This excess allows for a Dark Matter search with directional sensitivity. The surface laboratory configuration prevents the deterioration of the signal in the rock overburden and it emerges as the most powerful approach for a directional observation of boosted Dark Matter with high sensitivity. We show that, with this approach, a 10 kg module of the NEWSdm experiment exposed for one year at the Gran Sasso surface laboratory can probe Dark Matter masses between 1 keV/c$^2$ and 1 GeV/c$^2$ and cross-section values down to $10^{-30}$~cm$^2$ with a directional sensitive search., Comment: 15 pages, 14 figures, updated references, clarified discussion in intro section. Accepted in JCAP
Published: 2023
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2. Updated constraints on sterile neutrino mixing in the OPERA experiment using a new $\nu_e$ identification method

Author: Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Okateva, N., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Subjects: High Energy Physics - Experiment
Abstract: This paper describes a new $\nu_e$ identification method specifically designed to improve the low-energy ($< 30\,\mathrm{GeV}$) $\nu_e$ identification efficiency attained by enlarging the emulsion film scanning volume with the next generation emulsion readout system. A relative increase of 25-70% in the $\nu_e$ low-energy region is expected, leading to improvements in the OPERA sensitivity to neutrino oscillations in the framework of the 3 + 1 model. The method is applied to a subset of data where the detection efficiency increase is expected to be more relevant, and one additional $\nu_e$ candidate is found. The analysis combined with the $\nu_\tau$ appearance results improves the upper limit on $\sin^2 2\theta_{\mu e}$ to 0.016 at 90% C.L. in the MiniBooNE allowed region $\Delta m^2_{41} \sim 0.3\,\mathrm{eV}^2$., Comment: 13 pages, 6 figures
Published: 2022

3. Environmental sub-MeV neutron measurement at the Gran Sasso surface laboratory with a super-fine-grained nuclear emulsion detector

Author: Shiraishi, T., Akamatsu, S., Naka, T., Asada, T., De Lellis, G., Tioukov, V., Rosa, G., Kobayashi, R., Ambrosio, N., Alexandrov, A., and Sato, O.
Subjects: Physics - Instrumentation and Detectors, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The measurement of environmental neutrons is particularly important in the search for new physics, such as dark matter particles, because neutrons constitute an often-irreducible background source. The measurement of the neutron energy spectra in the sub-MeV scale is technically difficult because it requires a very good energy resolution and a very high $\gamma$-ray rejection power. In this study, we used a super-fine-grained nuclear emulsion, called Nano Imaging Tracker (NIT), as a neutron detector. The main target of neutrons is the hydrogen (proton) content of emulsion films. Through a topological analysis, proton recoils induced by neutron scattering can be detected as tracks with sub-micrometric accuracy. This method shows an extremely high $\gamma$-ray rejection power, at the level of $5 \times 10^7 ~ \gamma/\rm{cm}^2$, which is equivalent to 5 years accumulation of environmental $\gamma$-rays, and a very good energy and direction resolution even in the sub-MeV energy region. In order to carry out this measurement with sufficient statistics, we upgraded the automated scanning system to achieve a speed of 250 g/year/machine. We calibrated the detector performance of this system with 880 keV monochromatic neutrons: a very good agreement with the expectation was found for all the relevant kinematic variables. The application of the developed method to a sample exposed at the INFN Gran Sasso surface laboratory provided the first measurement of sub-MeV environmental neutrons with a flux of $(7.6 \pm 1.7) \times 10^{-3} \rm{cm}^{-2} \rm{s}^{-1}$ in the proton energy range between 0.25 and 1 MeV (corresponds to neutron energy range between 0.25 and 10 MeV), consistent with the prediction. The neutron energy and direction distributions also show a good agreement., Comment: 11 pages, 14 figures
Published: 2022
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4. Unusually strong electronic correlation and field-induced ordered phase in YbCo$_2$

Author: Valenta, J., Tsujii, N., Yamaoka, H., Honda, F., Hirose, Y., Sakurai, H., Terada, N., Naka, T., Nakane, T., Koizumi, T., Ishii, H., Hiraoka, N., and Mori, T.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: We report the first study of electrical resistivity, magnetization, and specific heat on YbCo$_2$. The measurements on a single-phased sample of YbCo$_2$ bring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature, C/T, keeps increasing logarithmically beyond 7 J/mol.K2 with decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3d and 4f electrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCo$_2$ is in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo$_2$, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.
Published: 2022
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5. Development of New Tracking Detector with Fine-grained Nuclear Emulsion for sub-MeV Neutron Measurement

Author: Shiraishi, T., Todoroki, I., Naka, T., Umemoto, A., Kobayashi, R., and Sato, O.
Subjects: Physics - Instrumentation and Detectors
Abstract: In this study, we have developed a new sub-MeV neutron detector that has a high position resolution, energy resolution, directional sensitivity, and low background. The detector is based on a super-fine-grained nuclear emulsion, called the Nano Imaging Tracker (NIT), and it is capable of detecting neutron induced proton recoils as tracks through topological analysis with sub-micrometric accuracy. We used a type of NIT with AgBr:I crystals of (98 +- 10) nm size dispersed in the gelatin. First, we calibrated the performance of NIT device for detecting monochromatic neutrons with sub-MeV energy generated by nuclear fusion reactions, and the detection efficiency for recoil proton tracks of more than 2 um range was consistently 100\% (the 1 sigma lower limit was 83%) in accordance with expectations by manual based analysis. In addition, recoil energy and angle distribution obtained good agreement with kinematical expectation. The primary neutron energy was reconstructed by using them, and it was evaluated as 42% with FWHM at 540 keV. Furthermore, we demonstrated newly developed an automatic track recognition system dedicated to the track range of more than a few micrometers. It achieved a recognition efficiency of (74 +- 4)%, and recoil energy and angle distribution obtained good agreement with manual analysis. Finally, it indicated the very high rejection power for gamma-rays., Comment: 16 pages, 13 figures
Published: 2021
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6. Cluster glass transition and relaxation in random spinel CoGa2O4

Author: Naka, T., Nakane, T., Ishii, S., Nakayama, M., Ohmura, A., Ishikawa, F., de Visser, A., Abe, H., and Uchikoshi, T.
Subjects: Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Disordered Systems and Neural Networks
Abstract: We report magnetic properties in the random spinel magnet CoGa2O4. Rietveld analysis of the x-ray diffraction profile for CoGa2O4 reveals that the Co and Ga ions are distributed randomly in the tetrahedral A-sites and octahedral B-sites in the cubic spinel structure. CoGa2O4 exhibits a spin-glass transition at TSG = 8.2 K that is confirmed by measurements of the dc- and ac-susceptibilities and thermoremanent magnetization (TRM) that develops below TSG. From the frequency dependence of the freezing temperature Tf for CoGa2O4, it is indicated that the relaxation time follows a Vogel-Fulcher law. Magnetic entropy is considerably reduced, probably because magnetic cluster formation developed even at T > TSG. The relaxation rate of TRM is considerably enhanced at TSG and decays rapidly above and below TSG. The time course of TRM is reproduced by non-exponential relaxation forms, such as a stretched exponential (Kohlrausch) as well as Ogielski and Weron relaxation forms. This behavior is displayed universally in glass systems, and the characteristic parameters associated with these functions were reasonable., Comment: 34 pages, 14 figures, 3 table
Published: 2020
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7. First observation of a tau neutrino charged current interaction with charm production in the Opera experiment

Author: Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., ić, K. Jakovč, Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., ek, B. Klič, Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Okateva, N., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., ević, M. Stipč, Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Subjects: High Energy Physics - Experiment
Abstract: An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the Opera target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with $c\overline{c}$ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a $\nu_{\tau}$ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated., Comment: 10 pages, 7 figures; Editors: Marco Roda, Chiara Sirignano and Gabriele Sirri
Published: 2019
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8. Final results on neutrino oscillation parameters from the OPERA experiment in the CNGS beam

Author: OPERA Collaboration, Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Okateva, N., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. Exploiting the OPERA detector capabilities, it was possible to isolate high purity samples of $\nu_{e}$, $\nu_{\mu}$ and $\nu_{\tau}$ charged current weak neutrino interactions, as well as neutral current weak interactions. In this Letter, the full dataset is used for the first time to test the three-flavor neutrino oscillation model and to derive constraints on the existence of a light sterile neutrino within the framework of the $3+1$ neutrino model. For the first time, tau and electron neutrino appearance channels are jointly used to test the sterile neutrino hypothesis. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit values obtained by MiniBooNE combining neutrino and antineutrino data are excluded at 3.3 $\sigma$ significance., Comment: 7 pages, 4 figures; Editors: Budimir Kli\v{c}ek and Matteo Tenti
Published: 2019
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9. Superconductivity under pressure in the Dirac semimetal PdTe2

Author: Leng, H., Ohmura, A., Anh, L. N., Ishikawa, F., Naka, T., Huang, Y. K., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: The Dirac semimetal PdTe$_2$ was recently reported to be a type-I superconductor ($T_c = $1.64 K, $\mu_0 H_c (0) = 13.6$ mT) with unusual superconductivity of the surface sheath. We here report a high-pressure study, $p \leq 2.5$ GPa, of the superconducting phase diagram extracted from ac-susceptibility and transport measurements on single crystalline samples. $T_c (p)$ shows a pronounced non-monotonous variation with a maximum $T_c = $1.91 K around 0.91 GPa, followed by a gradual decrease to 1.27 K at 2.5 GPa. The critical field of bulk superconductivity in the limit $T \rightarrow 0$, $H_c(0,p)$, follows a similar trend and consequently the $H_c(T,p)$-curves under pressure collapse on a single curve: $H_c(T,p)=H_c(0,p)[1-(T/T_c(p))^2]$. Surface superconductivity is robust under pressure as demonstrated by the large superconducting screening signal that persists for applied dc-fields $H_a > H_c$. Surprisingly, for $p \geq 1.41$ GPa the superconducting transition temperature at the surface $T_c^S$ is larger than $T_c$ of the bulk. Therefore surface superconductivity may possibly have a non-trivial nature and is connected to the topological surface states detected by ARPES. We compare the measured pressure variation of $T_c$ with recent results from band structure calculations and discuss the importance of a Van Hove singularity., Comment: manuscript 9 pages with 8 figures + supplemental material 3 pages with 6 figures
Published: 2019
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10. Latest results of the OPERA experiment on nu-tau appearance in the CNGS neutrino beam

Author: Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Favier, J., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Longhin, A., Loverre, P., Malenica, M., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Olchevsky, A., Okateva, N., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sadovsky, A., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Ustyuzhanin, A., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., and Yoon, C. S.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: OPERA is a long-baseline experiment designed to search for $\nu_{\mu}\to\nu_{\tau}$ oscillations in appearance mode. It was based at the INFN Gran Sasso laboratory (LNGS) and took data from 2008 to 2012 with the CNGS neutrino beam from CERN. After the discovery of $\nu_\tau$ appearance in 2015, with $5.1\sigma$ significance, the criteria to select $\nu_\tau$ candidates have been extended and a multivariate approach has been used for events identification. In this way the statistical uncertainty in the measurement of the oscillation parameters and of $\nu_\tau$ properties has been improved. Results are reported., Comment: 7 pages, 1 figure, conference: The 15th International Workshop on Tau Lepton Physics (tau2018)AB
Published: 2018

11. Measurement of the cosmic ray muon flux seasonal variation with the OPERA detector

Author: Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovčić, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Kliček, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Ljubičić, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Okateva, N., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipčević, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The OPERA experiment discovered muon neutrino into tau neutrino oscillations in appearance mode, detecting tau leptons by means of nuclear emulsion films. The apparatus was also endowed with electronic detectors with tracking capability, such as scintillator strips and resistive plate chambers. Because of its location, in the underground Gran Sasso laboratory, under 3800 m.w.e., the OPERA detector has also been used as an observatory for TeV muons produced by cosmic rays in the atmosphere. In this paper the measurement of the single muon flux modulation and of its correlation with the seasonal variation of the atmospheric temperature are reported.
Published: 2018
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12. Final results of the OPERA experiment on $\nu_\tau$ appearance in the CNGS beam

Author: OPERA Collaboration, Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Favier, J., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gornushkin, Y., Gorbunov, S., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Okateva, N., Olchevsky, A., Ogawa, S., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sadovsky, A., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibuya, H., Shibayama, E., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Ustyuzhanin, A., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., and Yoon, C. S.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA experiment was designed to study $\nu_\mu\to\nu_\tau$ oscillations in appearance mode in the CNGS neutrino beam. In this letter we report the final analysis of the full data sample collected between 2008 and 2012, corresponding to $17.97\cdot 10^{19}$ protons on target. Selection criteria looser than in previous analyses have produced ten $\nu_\tau$ candidate events, thus reducing the statistical uncertainty in the measurement of the oscillation parameters and of $\nu_\tau$ properties. A multivariate approach for event identification has been applied to the candidate events and the discovery of $\nu_\tau$ appearance is confirmed with an improved significance level of 6.1 $\sigma$. $\Delta m^2_{23}$ has been measured, in appearance mode, with an accuracy of 20%. The measurement of $\nu_\tau$ CC cross-section, for the first time with a negligible contamination from $\bar{\nu}_\tau$, and the first direct observation of the $\nu_\tau$ lepton number are also reported., Comment: 7 pages, 3 figures
Published: 2018
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13. Final results of the search for $\nu_{\mu} \to \nu_{e}$ oscillations with the OPERA detector in the CNGS beam

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Favier, J., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gornushkin, Y., Gorbunov, S., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Hosseini, B., Ishiguro, K., Iuliano, A., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meisel, F., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Okateva, N., Ogawa, S., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Shibuya, H., Shibayama, E., Shiraishi, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Vasina, S., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino interaction target, made of Emulsion Cloud Chamber, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by $\pi^0$s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate $m_{4}$ is introduced. At high $\Delta m^{2}_{41}$ $( \gtrsim 0.1~\textrm{eV}^{2})$, an upper limit on $\sin^2 2\theta_{\mu e}$ is set to 0.021 at 90% C.L. and $\Delta m^2_{41} \gtrsim 4 \times 10^{-3}~\textrm{eV}^{2}$ is excluded for maximal mixing in appearance mode., Comment: Editors: M. Tenti and S. Vasina
Published: 2018

14. Discovery potential for directional Dark Matter detection with nuclear emulsions

Author: Agafonova, N., Aleksandrov, A., Anokhina, A., Asada, T., Ashikhmin, V. V., Bodnarchuk, I., Buonaura, A., Chernyavskii, M., Chukanov, A., D'Ambrosio, N., De Lellis, G., Di Crescenzo, A., Di Marco, N., Dmitrievski, S., Enikeev, R. I., Fini, R. A., Galati, G., Gentile, V., Gorbunov, S., Gornushkin, Y., Guler, A. M., Ichiki, H., Katsuragawa, T., Konovalova, N., Kuge, K., Lauria, A., Lee, K. Y., Lista, L., Malgin, A. S., Managadze, A., Monacelli, P., Montesi, M. C., Naka, T., Okateva, N., Park, B. D., Podgrudkov, D., Polukhina, N., Pupilli, F., Roganova, T., Rogozhnikov, A., Rosa, G., Ryazhskaya, O. G., Sato, O., Shakiryanova, I. R., Shchedrina, T., Sirignano, C., Sohn, J. Y., Sotnikov, A., Starkov, N., Strolin, P., Tioukov, V., Umemoto, A., Ustyuzhanin, A., Yoon, C. S., Yoshimoto, M., and Vasina, S.
Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics, High Energy Physics - Phenomenology, Physics - Instrumentation and Detectors
Abstract: Direct Dark Matter searches are nowadays one of the most fervid research topics with many experimental efforts devoted to the search for nuclear recoils induced by the scattering of Weakly Interactive Massive Particles (WIMPs). Detectors able to reconstruct the direction of the nucleus recoiling against the scattering WIMP are opening a new frontier to possibly extend Dark Matter searches beyond the neutrino background. Exploiting directionality would also prove the galactic origin of Dark Matter with an unambiguous signal-to-background separation. Indeed, the angular distribution of recoiled nuclei is centered around the direction of the Cygnus constellation, while the background distribution is expected to be isotropic. Current directional experiments are based on gas TPC whose sensitivity is limited by the small achievable detector mass. In this paper we present the discovery potential of a directional experiment based on the use of a solid target made of newly developed nuclear emulsions and of optical read-out systems reaching unprecedented nanometric resolution., Comment: 8 pages, 12 figures
Published: 2017
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15. Readout technologies for directional WIMP Dark Matter detection

Author: Battat, J. B. R., Irastorza, I. G., Aleksandrov, A., Guler, M. Ali, Asada, T., Baracchini, E., Billard, J., Bosson, G., Bourrion, O., Bouvier, J., Buonaura, A., Burdge, K., Cebrian, S., Colas, P., Consiglio, L., Dafni, T., D'Ambrosio, N., Deaconu, C., De Lellis, G., Descombes, T., Di Crescenzo, A., Di Marco, N., Druitt, G., Eggleston, R., Ferrer-Ribas, E., Fusayasu, T., Galan, J., Galati, G., Garcia, J. A., Garza, J. G., Gentile, V., Garcia-Sciveres, M., Giomataris, Y., Guerrero, N., Guillaudin, O., Harton, J., Hashimoto, T., Hedges, M. T., Iguaz, F., Ikeda, T., Jaegle, I., Kadyk, J. A., Katsuragawa, T., Komura, S., Kubo, H., Kuge, K., Lamblin, J., Lauria, A., Lee, E. R., Lewis, P., Leyton, M., Loomba, D., Lopez, J. P., Luzon, G., Mayet, F., Mirallas, H., Miuchi, K., Mizumoto, T., Mizumura, Y., Monacelli, P., Monroe, J., Montesi, M. C., Naka, T., Nakamura, K., Nishimura, H., Ochi, A., Papevangelou, T., Parker, J. D., Phan, N. S., Pupilli, F., Richer, J. P., Riffard, Q., Rosa, G., Santos, D., Sawano, T., Sekiya, H., Seong, I. S., Snowden-Ifft, D. P., Spooner, N. J. C., Sugiyama, A., Taishaku, R., Takada, A., Takeda, A., Tanaka, M., Tanimori, T., Thorpe, T. N., Tioukov, V., Tomita, H., Umemoto, A., Vahsen, S. E., Yamaguchi, Y., Yoshimoto, M., and Zayas, E.
Subjects: Physics - Instrumentation and Detectors, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract: The measurement of the direction of WIMP-induced nuclear recoils is a compelling but technologically challenging strategy to provide an unambiguous signature of the detection of Galactic dark matter. Most directional detectors aim to reconstruct the dark-matter-induced nuclear recoil tracks, either in gas or solid targets. The main challenge with directional detection is the need for high spatial resolution over large volumes, which puts strong requirements on the readout technologies. In this paper we review the various detector readout technologies used by directional detectors. In particular, we summarize the challenges, advantages and drawbacks of each approach, and discuss future prospects for these technologies., Comment: 58 pages, 26 figures, accepted by Physics Reports
Published: 2016
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16. High-pressure study of the basal-plane anisotropy of the upper critical field of the topological superconductor SrxBi2Se3

Author: Nikitin, A. M., Pan, Y., Huang, Y. K., Naka, T., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: We report a high-pressure transport study of the upper-critical field, $B_{c2}(T)$, of the topological superconductor Sr$_{0.15}$Bi$_2$Se$_3$ ($T_c = 3.0$ K). $B_{c2}(T)$ was measured for magnetic fields directed along two orthogonal directions, $a$ and $a^*$, in the trigonal basal plane. While superconductivity is rapidly suppressed at the critical pressure $p_c \sim 3.5$ GPa, the pronounced two-fold basal-plane anisotropy $B_{c2}^a/B_{c2}^{a^*} = 3.2$ at $T=0.3$ K, recently reported at ambient pressure (Pan et al., 2016), is reinforced and attains a value of $\sim 5$ at the highest pressure (2.2 GPa). The data reveal that the unconventional superconducting state with broken rotational symmetry is robust under pressure.
Published: 2016
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17. NEWS: Nuclear Emulsions for WIMP Search

Author: Aleksandrov, A., Anokhina, A., Asada, T., Bender, D., Bodnarchuk, I., Buonaura, A., Buontempo, S., Chernyavskii, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Di Crescenzo, A., Di Marco, N., Dmitrievski, S., Dzhatdoev, T., Fini, R. A., Furuya, S., Galati, G., Gentile, V., Gorbunov, S., Gornushkin, Y., Guler, A. M., Ichiki, H., Kamiscioglu, C., Kamiscioglu, M., Katsuragawa, T., Kimura, M., Konovalova, N., Kuge, K., Lauria, A., Loverre, P., Machii, S., Managadze, A., Monacelli, P., Montesi, M. C., Naka, T., Nakamura, M., Nakano, T., Pastore, A., Podgrudkov, D., Polukhina, N., Pupilli, F., Roganova, T., Rosa, G., Sato, O., Shchedrina, T., Simone, S., Sirignano, C., Sotnikov, A., Starkov, N., Strolin, P., Tawara, Y., Tioukov, V., Umemoto, A., Vladymyrov, M., Yoshimoto, M., and Zemskova, S.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract: Nowadays there is compelling evidence for the existence of dark matter in the Universe. A general consensus has been expressed on the need for a directional sensitive detector to confirm, with a complementary approach, the candidates found in conventional searches and to finally extend their sensitivity beyond the limit of neutrino-induced background. We propose here the use of a detector based on nuclear emulsions to measure the direction of WIMP-induced nuclear recoils. The production of nuclear emulsion films with nanometric grains is established. Several measurement campaigns have demonstrated the capability of detecting sub-micrometric tracks left by low energy ions in such emulsion films. Innovative analysis technologies with fully automated optical microscopes have made it possible to achieve the track reconstruction for path lengths down to one hundred nanometers and there are good prospects to further exceed this limit. The detector concept we propose foresees the use of a bulk of nuclear emulsion films surrounded by a shield from environmental radioactivity, to be placed on an equatorial telescope in order to cancel out the effect of the Earth rotation, thus keeping the detector at a fixed orientation toward the expected direction of galactic WIMPs. We report the schedule and cost estimate for a one-kilogram mass pilot experiment, aiming at delivering the first results on the time scale of six years.
Published: 2016

18. Rotational symmetry breaking in the topological superconductor Sr$_x$Bi$_2$Se$_3$ probed by upper-critical field experiments

Author: Pan, Y., Nikitin, A. M., Araizi, G. K., Huang, Y. K., Matsushita, Y., Naka, T., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi$_2$Se$_3$. Topological superconductors are predicted to be unconventional, with mixed even and odd parity Cooper pairs states. An adequate probe to test for unconventional superconductivity is the upper critical field, $B_{c2}$. For a standard BCS layered superconductor $B_{c2}$ shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting Sr$_x$Bi$_2$Se$_3$ crystals ($T_c = 3.0$~K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of $B_{c2}$ when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of $B_{c2}$ indicates unconventional superconductivity with an odd-parity polarized triplet Cooper pair state ($\Delta_4$-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms., Comment: 16 pages, including 4 figures
Published: 2016

19. Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches

Author: Alexandrov, A., Asada, T., Buonaura, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., Di Crescenzo, A., Di Marco, N., Di Vacri, M. L., Furuya, S., Galati, G., Gentile, V., Katsuragawa, T., Laubenstein, M., Lauria, A., Loverre, P. F., Machii, S., Monacelli, P., Montesi, M. C., Naka, T., Pupilli, F., Rosa, G., Sato, O., Strolin, P., Tioukov, V., Umemoto, A., and Yoshimoto, M.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract: Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.06 neutrons per year per kilogram, fully compatible with the design of a 10 kg$\times$year exposure., Comment: Revised version
Published: 2015
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20. Discovery of tau neutrino appearance in the CNGS neutrino beam with the OPERA experiment

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bender, D., Bertolin, A., Bodnarchuk, I., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Büttner, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Goldberg, J., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, H., Hollnagel, A., Hosseini, B., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Ljubicic, A., Longhin, A., Loverre, P. F., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matsushita, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Olchevsky, A., Omura, T., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Schmidt-Parzefall, W., Shakirianova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladymyrov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., and Zemskova, S.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA experiment was designed to search for $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations in appearance mode, i.e. by detecting the $\tau$-leptons produced in charged current $\nu_{\tau}$ interactions. The experiment took data from 2008 to 2012 in the CERN Neutrinos to Gran Sasso beam. The observation of $\nu_{\mu} \rightarrow \nu_{\tau}$ appearance, achieved with four candidate events in a sub-sample of the data, was previously reported. In this paper, a fifth $\nu_{\tau}$ candidate event, found in an enlarged data sample, is described. Together with a further reduction of the expected background, the candidate events detected so far allow assessing the discovery of $\nu_{\mu}\rightarrow \nu_{\tau}$ oscillations in appearance mode with a significance larger than 5 $\sigma$., Comment: 7 pages, 3 figures
Published: 2015
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21. A facility to Search for Hidden Particles (SHiP) at the CERN SPS

Author: SHiP Collaboration, Anelli, M., Aoki, S., Arduini, G., Back, J. J., Bagulya, A., Baldini, W., Baranov, A., Barker, G. J., Barsuk, S., Battistin, M., Bauche, J., Bay, A., Bayliss, V., Bellagamba, L., Bencivenni, G., Bertani, M., Bezshyyko, O., Bick, D., Bingefors, N., Blondel, A., Bogomilov, M., Boyarsky, A., Bonacorsi, D., Bondarenko, D., Bonivento, W., Borburgh, J., Bradshaw, T., Brenner, R., Breton, D., Brook, N., Bruschi, M., Buonaura, A., Buontempo, S., Cadeddu, S., Calcaterra, A., Calviani, M., Campanelli, M., Capoccia, C., Cecchetti, A., Chatterjee, A., Chauveau, J., Chepurnov, A., Chernyavskiy, M., Ciambrone, P., Cicalo, C., Conti, G., Cornelis, K., Courthold, M., Dallavalle, M. G., D'Ambrosio, N., De Lellis, G., De Serio, M., Dedenko, L., Di Crescenzo, A., Di Marco, N., Dib, C., Dietrich, J., Dijkstra, H., Domenici, D., Donskov, S., Druzhkin, D., Ebert, J., Egede, U., Egorov, A., Egorychev, V., Alaoui, M. A. El, Enik, T., Etenko, A., Fabbri, F., Fabbri, L., Fedorova, G., Felici, G., Ferro-Luzzi, M., Fini, R. A., Franke, M., Fraser, M., Galati, G., Giacobbe, B., Goddard, B., Golinka-Bezshyyko, L., Golubkov, D., Golutvin, A., Gorbunov, D., Graverini, E., Grenard, J-L, Guler, A. M., Hagner, C., Hakobyan, H., Helo, J. C., van Herwijnen, E., Horvath, D., Iacovacci, M., Iaselli, G., Jacobsson, R., Kadenko, I., Kamiscioglu, M., Kamiscioglu, C., Khaustov, G., Khotjansev, A., Kilminster, B., Kim, V., Kitagawa, N., Kodama, K., Kolesnikov, A., Kolev, D., Komatsu, M., Konovalova, N., Koretskiy, S., Korolko, I., Korzenev, A., Kovalenko, S., Kudenko, Y., Kuznetsova, E., Lacker, H., Lai, A., Lanfranchi, G., Lauria, A., Lebbolo, H., Levy, J. -M., Lista, L., Loverre, P., Lukiashin, A., Lyubovitskij, V. E., Malinin, A., Manfredi, M., Perillo-Marcone, A., Marrone, A., Matev, R., Messomo, E. N., Mermod, P., Mikado, S., Mikhaylov, Yu., Miller, J., Milstead, D., Mineev, O., Mingazheva, R., Mitselmakher, G., Miyanishi, M., Monacelli, P., Montanari, A., Montesi, M. C., Morello, G., Morishima, K., Movtchan, S., Murzin, V., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nurakhov, N., Obinyakov, B., Ocalan, K., Ogawa, S., Oreshkin, V., Orlov, A., Osborne, J., Pacholek, P., Panman, J., Paoloni, A., Paparella, L., Pastore, A., Patel, M., Petridis, K., Petrushin, M., Poli-Lener, M., Polukhina, N., Polyakov, V., Prokudin, M., Puddu, G., Pupilli, F., Rademakers, F., Rakai, A., Rawlings, T., Redi, F., Ricciardi, S., Rinaldesi, R., Roganova, T., Rogozhnikov, A., Rokujo, H., Romaniouk, A., Rosa, G., Rostovtseva, I., Rovelli, T., Ruchayskiy, O., Ruf, T., Saitta, G., Samoylenko, V., Samsonov, V., Ull, A. Sanz, Saputi, A., Sato, O., Schmidt-Parzefall, W., Serra, N., Sgobba, S., Shaposhnikov, M., Shatalov, P., Shaykhiev, A., Shchutska, L., Shevchenko, V., Shibuya, H., Shitov, Y., Silverstein, S., Simone, S., Skorokhvatov, M., Smirnov, S., Solodko, E., Sosnovtsev, V., Spighi, R., Spinetti, M., Starkov, N., Storaci, B., Strabel, C., Strolin, P., Takahashi, S., Teterin, P., Tioukov, V., Tommasini, D., Treille, D., Tsenov, R., Tshchedrina, T., Ustyuzhanin, A., Vannucci, F., Venturi, V., Villa, M., Vincke, Heinz, Vincke, Helmut, Vladymyrov, M., Xella, S., Yalvac, M., Yershov, N., Yilmaz, D., Yilmazer, A. U., Vankova-Kirilova, G., Zaitsev, Y., and Zoccoli, A.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract: A new general purpose fixed target facility is proposed at the CERN SPS accelerator which is aimed at exploring the domain of hidden particles and make measurements with tau neutrinos. Hidden particles are predicted by a large number of models beyond the Standard Model. The high intensity of the SPS 400~GeV beam allows probing a wide variety of models containing light long-lived exotic particles with masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. The experimental programme of the proposed facility is capable of being extended in the future, e.g. to include direct searches for Dark Matter and Lepton Flavour Violation., Comment: Technical Proposal
Published: 2015

22. Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bender, D., Bertolin, A., Bodnarchuk, I., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Büttner, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Goldberg, J., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hollnagel, A., Hosseini, B., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Ljubicic, A., Longhin, A., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Omura, T., Ozaki, K., Paoloni, A., Paparella, L., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakirianova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladymyrov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., and Zemskova, S.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA experiment, exposed to the CERN to Gran Sasso $\nu_\mu$ beam, collected data from 2008 to 2012. Four oscillated $\nu_\tau$ Charged Current interaction candidates have been detected in appearance mode, which are consistent with $\nu_\mu \to \nu_\tau$ oscillations at the atmospheric $\Delta m^2$ within the "standard" three-neutrino framework. In this paper, the OPERA $\nu_\tau$ appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino., Comment: 11 pages, 4 figures; reference to Planck result updated in the Introduction. Submitted to JHEP
Published: 2015
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23. Structural characterization and magnetic properties of iron-phosphate glass prepared by sol-gel method

Author: Khan, I., Sunakawa, K., Higashinaka, R., Matsuda, T.D., Aoki, Y., Nomura, K., Kuzmann, E., Homonnay, Z., Sinkó, K., Naka, T., Nakane, T., Krehula, S., Musić, S., and Kubuki, S.
Published: 2020
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24. Phase transitions and slow spin dynamics of slightly inverted A-site spinel CoAl2−x Ga x O4

Author: Naka, T, primary, Valenta, J, additional, Nakane, T, additional, Ishii, S, additional, Nakayama, M, additional, Mamiya, H, additional, Takehana, K, additional, Tsujii, N, additional, Imanaka, Y, additional, Matsushita, Y, additional, Abe, H, additional, Uchikoshi, T, additional, and Yusa, H, additional
Published: 2023
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25. Observation of nu_tau appearance in the CNGS beam with the OPERA experiment

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Asada, T., Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Buttne, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Giacomelli, G., Goellnitz, C., Goldberg, J., Gornushkin, Y., Grella, G., Guler, M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Katsuragawa, T., Kawada, J., Kawahara, H., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malenica, M., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Meyer, M., Mikado, S., Miyanishi, M., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Umemoto, A., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Yaguchi, I., Yoshimoto, M., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA experiment is searching for nu_mu -> nu_tau oscillations in appearance mode i.e. via the direct detection of tau leptons in nu_tau charged current interactions. The evidence of nu_mu -> nu_tau appearance has been previously reported with three nu_tau candidate events using a sub-sample of data from the 2008-2012 runs. We report here a fourth nu_tau candidate event, with the tau decaying into a hadron, found after adding the 2012 run events without any muon in the final state to the data sample. Given the number of analysed events and the low background, nu_mu -> nu_tau oscillations are established with a significance of 4.2sigma., Comment: Submitted to Progress of Theoretical and Experimental Physics (PTEP)
Published: 2014
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26. Angular variation of the magnetoresistance of the superconducting ferromagnet UCoGe

Author: Bay, T. V., Nikitin, A. M., Naka, T., McCollam, A., Huang, Y. K., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: We report a magnetoresistance study of the superconducting ferromagnet UCoGe. The data, taken on single-crystalline samples, show a pronounced structure at $B^* = 8.5$~T for a field applied along the ordered moment $m_0$. Angle dependent measurements reveal this field-induced phenomenon has an uniaxial anisotropy. Magnetoresistance measurements under pressure show a rapid increase of $B^*$ to 12.8~T at 1.0~GPa. We discuss $B^*$ in terms of a field induced polarization change. Upper critical field measurements corroborate the unusual S-shaped $B_{c2}(T)$-curve for a field along the $b$-axis of the orthorhombic unit cell., Comment: 6 pages, 5 figures; accepted for publication in Phys. Rev. B
Published: 2014
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27. Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Büttner, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Giacomelli, G., Goellnitz, C., Goldberg, J., Goloubkov, D., Gornushkin, Y., Grella, G., Guler, M., Gustavino, C., Hagner, C., Hara, T., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kawada, J., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Meyer, M., Mikado, S., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Rokujo, H., Roganova, T., Rosa, G., Rostovtseva, I., Ryazhskaya, O., Sato, O., Sato, Y., Schembri, A., Shakiryanova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Zaitsev, Y., Zemskova, S., and Zghiche, A.
Subjects: Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract: The OPERA long-baseline neutrino-oscillation experiment has observed the direct appearance of $\nu_\tau$ in the CNGS $\nu_\mu$ beam. Two large muon magnetic spectrometers are used to identify muons produced in the $\tau$ leptonic decay and in $\nu_\mu^{CC}$ interactions by measuring their charge and momentum. Besides the kinematic analysis of the $\tau$ decays, background resulting from the decay of charmed particles produced in $\nu_\mu^{CC}$ interactions is reduced by efficiently identifying the muon track. A new method for the charge sign determination has been applied, via a weighted angular matching of the straight track-segments reconstructed in the different parts of the dipole magnets. Results obtained for Monte Carlo and real data are presented. Comparison with a method where no matching is used shows a significant reduction of up to 40\% of the fraction of wrongly determined charges., Comment: 10 pages. Improvements in the text
Published: 2014

28. Procedure for short-lived particle detection in the OPERA experiment and its application to charm decays

Author: Agafonova, N., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Buttner, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Giacomelli, G., Gollnitz, C., Goldberg, J., Gornushkin, Y., Grella, G., Guler, M., Gustavino, C., Hagner, C., Hara, T., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kawada, J., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Rokujo, H., Roganova, T., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strauss, T., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA experiment, designed to perform the first observation of $\nu_\mu \rightarrow \nu_\tau$ oscillations in appearance mode through the detection of the $\tau$ leptons produced in $\nu_\tau$ charged current interactions, has collected data from 2008 to 2012. In the present paper, the procedure developed to detect $\tau$ particle decays, occurring over distances of the order of 1 mm from the neutrino interaction point, is described in detail. The results of its application to the search for charmed hadrons are then presented as a validation of the methods for $\nu_\tau$ appearance detection.
Published: 2014
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29. Measurement of TeV atmospheric muon charge ratio with the full OPERA data

Author: Agafonova, N., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Buettner, B., Chernyavsky, M., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Giacomelli, G., Goellnitz, C., Goldberg, J., Gornushkin, Y., Grella, G., Guler, M., Gustavino, C., Hagner, C., Hara, T., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kawada, J., Kim, J. H., Kim, S. H., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Malenica, M., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Rokujo, H., Roganova, T., Rosa, G., Ryazhskaya, O., Sato, O., Schembri, A., Shakiryanova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA detector, designed to search for $\nu_{\mu} \to \nu_{\tau}$ oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio $R_{\mu} \equiv N_{\mu^+}/N_{\mu^-}$ was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1-20 TeV investigated by OPERA, $R_{\mu}$ is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to $200$ TeV/nucleon primary energy., Comment: 8 pages, 2 figures, 4 tables
Published: 2014
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30. Evidence for $\nu_\mu \to \nu_\tau$ appearance in the CNGS neutrino beam with the OPERA experiment

Author: Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Asada, T., Autiero, D., Dhahbi, A. Ben, Badertscher, A., Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Brunet, F., Brunetti, G., Buonaura, A., Buontempo, S., Buettner, B., Chaussard, L., Chernyavsky, M., Chiarella, V., Chukanov, A., Consiglio, L., D'Ambrosio, N., De Lellis, G., De Serio, M., Sanchez, P. Del Amo, Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Favier, J., Ferber, T., Ferone, G., Fini, R. A., Fukuda, T., Galati, G., Garfagnini, A., Giacomelli, G., Goellnitz, C., Goldberg, J., Gornushkin, Y., Grella, G., Grianti, F., Guler, M., Gustavino, C., Hagner, C., Hakamata, K., Hara, T., Hayakawa, T., Hierholzer, M., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Ishikawa, M., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Katsuragawa, T., Kawada, J., Kawahara, H., Kim, J. H., Kim, S. H., Kimura, M., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Marteau, J., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Migliozzi, P., Mikado, S., Miyanishi, M., Miyashita, E., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pastore, A., Patrizii, L., Pennacchio, E., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pretzl, K., Pupilli, F., Rescigno, R., Roda, M., Rokujo, H., Roganova, T., Rosa, G., Rostovtseva, I., Rubbia, A., Ryazhskaya, O., Sato, O., Sato, Y., Schembri, A., Schmidt-Parzefal, W., Shakiryanova, I., Shchedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strauss, T., Strolin, P., Suzuki, K., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Yoshida, J., Yoshimoto, M., Zaitsev, Y., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The OPERA experiment is designed to search for $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations in appearance mode i.e. through the direct observation of the $\tau$ lepton in $\nu_{\tau}$ charged current interactions. The experiment has taken data for five years, since 2008, with the CERN Neutrino to Gran Sasso beam. Previously, two $\nu_{\tau}$ candidates with a $\tau$ decaying into hadrons were observed in a sub-sample of data of the 2008-2011 runs. Here we report the observation of a third $\nu_\tau$ candidate in the $\tau^-\to\mu^-$ decay channel coming from the analysis of a sub-sample of the 2012 run. Taking into account the estimated background, the absence of $\nu_{\mu} \rightarrow \nu_{\tau}$ oscillations is excluded at the 3.4 $\sigma$ level., Comment: 9 pages, 5 figures, 1 tables
Published: 2014
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31. OPERA tau neutrino charged current interactions

Author: Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Bertolin, A., Bozza, C., Brugnera, R., Buonaura, A., Buontempo, S., Chernyavskiy, M., Chukanov, A., Consiglio, L., D’Ambrosio, N., De Lellis, G., De Serio, M., del Amo Sanchez, P., Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Ereditato, A., Fini, R. A., Fornari, F., Fukuda, T., Galati, G., Garfagnini, A., Gentile, V., Goldberg, J., Gorbunov, S., Gornushkin, Y., Grella, G., Guler, A. M., Gustavino, C., Hagner, C., Hara, T., Hayakawa, T., Hollnagel, A., Ishiguro, K., Iuliano, A., Jakovčić, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Kim, S. H., Kitagawa, N., Kliček, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Laudisio, F., Lauria, A., Lavasa, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Mikado, S., Miyanishi, M., Mizutani, F., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Niwa, K., Ogawa, S., Okateva, N., Ozaki, K., Paoloni, A., Park, B. D., Pasqualini, L., Pastore, A., Patrizii, L., Pessard, H., Podgrudkov, D., Polukhina, N., Pozzato, M., Pupilli, F., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Ryazhskaya, O., Sato, O., Shakirianova, I., Schembri, A., Shchedrina, T., Shibayama, E., Shibuya, H., Shiraishi, T., Šimko, T., Simone, S., Sirignano, C., Sirri, G., Sotnikov, A., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipčević, M., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tsanaktsidis, I., Tufanli, S., Ustyuzhanin, A., Vasina, S., Vidal García, M., Vilain, P., Voevodina, E., Votano, L., Vuilleumier, J. L., Wilquet, G., and Yoon, C. S.
Published: 2021
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32. New results on $\nu_\mu \to \nu_\tau$ appearance with the OPERA experiment in the CNGS beam

Author: OPERA Collaboration, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Asada, T., Autiero, D., Badertscher, A., Dhahbi, A. Ben, Bender, D., Bertolin, A., Bozza, C., Brugnera, R., Brunetti, G., Buettner, B., Buontempo, S., Chaussard, L., Chernyavskiy, M., Chiarella, V., Chukanov, A., Consiglio, L., D'Ambrosio, N., Sanchez, P. Del Amo, De Lellis, G., De Serio, M., Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Ebert, J., Ereditato, A., Favier, J., Ferber, T., Fini, R. A., Fukuda, T., Garfagnini, A., Giacomelli, G., Goellnitz, C., Goldberg, J., Gornushkin, Y., Grella, G., Grianti, F., Guler, A. M., Gustavino, C., Hagner, C., Hakamata, K., Hara, T., Hayakawa, T., Hierholzer, M., Hollnagel, A., Hosseini, B., Ishida, H., Ishiguro, K., Ishikawa, M., Jakovcic, K., Jollet, C., Kamiscioglu, C., Kamiscioglu, M., Katsuragawa, T., Kawahara, H., Kawada, J., Kim, J. H., Kim, S. H., Kimura, M., Kitagawa, N., Klicek, B., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lauria, A., Lenkeit, J., Ljubicic, A., Longhin, A., Loverre, P., Malgin, A., Mandrioli, G., Marteau, J., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meregaglia, A., Migliozzi, P., Mikado, S., Minotti, A., Miyanishi, M., Miyashita, E., Monacelli, P., Montesi, M. C., Morishima, K., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Niwa, K., Ogawa, S., Okateva, N., Olshevsky, A., Omura, T., Ozaki, K., Paoloni, A., Park, B. D., Park, I. G., Pastore, A., Patrizii, L., Pennacchio, E., Pessard, H., Pistillo, C., Podgrudkov, D., Polukhina, N., Pozzato, M., Pretzl, K., Pupilli, F., Rescigno, R., Roda, M., Roganova, T., Rokujo, H., Rosa, G., Rostovtseva, I., Rubbia, A., Russo, A., Ryazhskaya, O., Sato, O., Sato, Y., Schembri, A., Schmidt-Parzefall, W., Shakiryanova, I., Schcedrina, T., Sheshukov, A., Shibuya, H., Shiraishi, T., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S. M., Stipcevic, M., Strauss, T., Strolin, P., Suzuki, K., Takahashi, S., Tenti, M., Terranova, F., Tioukov, V., Tolun, P., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yoon, C. S., Yoshida, J., Yoshimoto, M., Zaitsev, Y., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the $\nu_\mu \to \nu_\tau$ channel, via the detection of the $\tau$-leptons created in charged current $\nu_\tau$ interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first $\nu_\tau$ candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional $\nu_\tau$ candidate has been observed. The significance of the two events in terms of a $\nu_\mu \to \nu_\tau$ oscillation signal is of 2.40 $\sigma$., Comment: 33 pages, 12 figures, 5 tables. Prepared for submission to JHEP
Published: 2013

33. Superconductivity in non-centrosymmetric YPtBi under pressure

Author: Bay, T. V., Naka, T., Huang, Y. K., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: We report a high-pressure single-crystal study of the non-centrosymmetric superconductor YPtBi ($T_c = 0.77$ K). Magnetotransport measurements show a weak metallic behavior with a carrier concentration $n \simeq 2.2 \times 10^{19}$ cm$^{-3}$. Resistivity measurements up to $p = 2.51$ GPa reveal superconductivity is promoted by pressure. The reduced upper critical field $B_{c2}(T)$ curves collapse onto a single curve, with values that exceed the model values for spin-singlet superconductivity. The $B_{c2}$ data point to an odd-parity component in the superconducting order parameter, in accordance with predictions for non-centrosymmetric superconductors., Comment: 5 pages, 5 figures; submitted for publication
Published: 2012
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34. Superconductivity in the doped topological insulator Cu$_x$Bi$_2$Se$_3$ under high pressure

Author: Bay, T. V., Naka, T., Huang, Y. K., Luigjes, H., Golden, M. S., and de Visser, A.
Subjects: Condensed Matter - Superconductivity
Abstract: We report a high-pressure single crystal study of the topological superconductor Cu$_x$Bi$_2$Se$_3$. Resistivity measurements under pressure show superconductivity is depressed smoothly. At the same time the metallic behavior is gradually lost. The upper critical field data $B_{c2}(T)$ under pressure collapse onto a universal curve. The absence of Pauli limiting and the comparison of $B_{c2}(T)$ to a polar state function point to spin-triplet superconductivity, but an anisotropic spin-singlet state cannot be discarded completely., Comment: 5 pages, 4 figures; accepted for publication in PRL
Published: 2011
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35. Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

Author: The OPERA Collaboration, Adam, T., Agafonova, N., Aleksandrov, A., Altinok, O., Sanchez, P. Alvarez, Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Autiero, D., Badertscher, A., Dhahbi, A. Ben, Bertolin, A., Bozza, C., Brugiere, T., Brugnera, R., Brunet, F., Brunetti, G., Buontempo, S., Carlus, B., Cavanna, F., Cazes, A., Chaussard, L., Chernyavsky, M., Chiarella, V., Chukanov, A., Colosimo, G., Crespi, M., D'Ambrosio, N., De Lellis, G., De Serio, M., Declais, Y., Sanchez, P. del Amo, Di Capua, F., Di Crescenzo, A., Di Ferdinando, D., Di Marco, N., Dmitrievsky, S., Dracos, M., Duchesneau, D., Dusini, S., Dzhatdoev, T., Ebert, J., Efthymiopoulos, I., Egorov, O., Ereditato, A., Esposito, L. S., Favier, J., Ferber, T., Fini, R. A., Fukuda, T., Garfagnini, A., Giacomelli, G., Giorgini, M., Giovannozzi, M., Girerd, C., Goldberg, J., Gollnitz, C., Golubkov, D., Goncharova, L., Gornushkin, Y., Grella, G., Grianti, F., Gschwendtner, E., Guerin, C., Guler, A. M., Gustavino, C., Hagner, C., Hamada, K., Hara, T., Enikeev, R., Hierholzer, M., Hollnagel, A., Ieva, M., Ishida, H., Ishiguro, K., Jakovcic, K., Jollet, C., Jones, M., Juget, F., Kamiscioglu, M., Kawada, J., Kim, S. H., Kimura, M., Kiritsis, E., Kitagawa, N., Klicek, B., Knuesel, J., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Lazzaro, C., Lenkeit, J., Ljubicic, A., Longhin, A., Malgin, A., Mandrioli, G., Marteau, J., Matsuo, T., Matveev, V., Mauri, N., Mazzoni, A., Medinaceli, E., Meisel, F., Meregaglia, A., Migliozzi, P., Mikado, S., Missiaen, D., Monacelli, P., Morishima, K., Moser, U., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Nakatsuka, Y., Naumov, D., Nikitina, V., Nitti, F., Ogawa, S., Okateva, N., Olchevsky, A., Palamara, O., Paoloni, A., Park, B. D., Park, I. G., Pastore, A., Patrizii, L., Pennacchio, E., Pessard, H., Pistillo, C., Polukhina, N., Pozzato, M., Pretzl, K., Pupilli, F., Rescigno, R., Riguzzi, F., Roganova, T., Rokujo, H., Rosa, G., Rostovtseva, I., Rubbia, A., Russo, A., Ryasny, V., Ryazhskaya, O., Sato, O., Sato, Y., Sahnoun, Z., Schembri, A., Schuler, J., Lavina, L. Scotto, Serrano, J., Shakiryanova, I., Sheshukov, A., Shibuya, H., Shoziyoev, G., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Song, J. S., Spinetti, M., Stanco, L., Starkov, N., Stellacci, S., Stipcevic, M., Strauss, T., Takahashi, S., Tenti, M., Terranova, F., Tezuka, I., Tioukov, V., Tolun, P., Tran, N. T., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. -L., Wilquet, G., Wonsak, B., Wurtz, J., Yakushev, V., Yoon, C. S., Yoshida, J., Zaitsev, Y., Zemskova, S., and Zghiche, A.
Subjects: High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract: The OPERA neutrino experiment at the underground Gran Sasso Laboratory has measured the velocity of neutrinos from the CERN CNGS beam over a baseline of about 730 km. The measurement is based on data taken by OPERA in the years 2009, 2010 and 2011. Dedicated upgrades of the CNGS timing system and of the OPERA detector, as well as a high precision geodesy campaign for the measurement of the neutrino baseline, allowed reaching comparable systematic and statistical accuracies. An arrival time of CNGS muon neutrinos with respect to the one computed assuming the speed of light in vacuum of (6.5 +/- 7.4(stat.)((+8.3)(-8.0)sys.))ns was measured corresponding to a relative difference of the muon neutrino velocity with respect to the speed of light (v-c)/c =(2.7 +/-3.1(stat.)((+3.4)(-3.3)(sys.))x10^(-6). The above result, obtained by comparing the time distributions of neutrino interactions and of protons hitting the CNGS target in 10.5 microseconds long extractions, was confirmed by a test performed at the end of 2011 using a short bunch beam allowing to measure the neutrino time of flight at the single interaction level., Comment: 34 pages, 22 figures This version replaces all previous ones
Published: 2011
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36. R&D Status of Nuclear Emulsion For Directional Dark Matter Search

Author: Naka, T., Kimura, M., Nakamura, M., Sato, O., Nakano, T., Asada, T., Tawara, Y., and Suzuki, Y.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract: In this study, we are doing R&D for directional dark matter search with nuclear emulsion. First of all, higher resolution nuclear emulsion with fine silver halide crystals was developed in the production facility of emulsion at Nagoya university, and we confirmed that it can detect the expected nuclear recoil tracks. The readout of submicron tracks was required the new technology. We developed the expansion technique, and could readout the signal by shape analysis with optical microscopy. The two dimensional angular resolution is 36 degrees at the original track length of range from 150nm to 200nm with optical microscopy. Finally we demonstrated by using recoiled nuclei induced by 14.8MeV neutron, and confirmed the technique.Moreover, we developed the X-ray microscope system with SPring-8 as final check with higher resolution of selected candidate tracks with optical microscopy. The angular resolution was improved from 31 degrees with optical microscopy to 17degrees with X-ray microscopy at the track length of range from 150nm to 250nm. We are developing the practical system and planning for start of the test running with prototype detector., Comment: Proceedings of the 3rd International conference on Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 2011
Published: 2011
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37. Weak itinerant ferromagnetism in Heusler type Fe2VAl0.95

Author: Sato, K., Naka, T., Taguchi, M., Nakane, T., Ishikawa, F., Yamada, Yuh, Takaesu, Y., Nakama, T., de Visser, A., and Matsushita, A.
Subjects: Condensed Matter - Strongly Correlated Electrons, Condensed Matter - Materials Science
Abstract: We report measurements of the magnetic, transport and thermal properties of the Heusler type compound Fe2VAl0.95. We show that while stoichiometric Fe2VAl is a non-magnetic semi-metal a 5% substitution on the Al-site with the 3d elements Fe and V atoms leads to a ferromagnetic ground state with a Curie temperature TC = 33+-3 K and a small ordered moment ms = 0.12 mB/Fe in Fe2VAl0.95. The reduced value of the ratio ms/mp = 0.08, where mp = 1.4 mB/Fe is the effective Curie-Weiss moment, together with the analysis of the magnetization data M(H,T), show magnetism is of itinerant nature. The specific heat shows an unusual temperature variation at low temperatures with an enhanced Sommerfeld coefficient, g = 12 mJK-2mol-1. The resistivity, r(T), is metallic and follows a power law behavior r(T) = r0+AT^n with n = 1.5 below TC. With applying pressure, TC decreases with the rate of (1/TC)(dTC /dP) = -0.061 GPa-1. We conclude substitution on the Al-site with Fe and V atoms results in itinerant ferromagnetism with a low carrier density., Comment: 27 pages, 9 figures
Published: 2010
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38. The superconducting ferromagnet UCoGe

Author: Gasparini, A., Huang, Y. K., Huy, N. T., Klaasse, J. C. P., Naka, T., Slooten, E., and de Visser, A.
Subjects: Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract: The correlated metal UCoGe is a weak itinerant ferromagnet with a Curie temperature T_C = 3 K and a superconductor with a transition temperature T_s = 0.6 K. We review its basic thermal, magnetic - on the macro and microscopic scale - and transport properties, as well as the response to high pressure. The data unambiguously show that superconductivity and ferromagnetism coexist below T_s = 0.6 K and are carried by the same 5f electrons. We present evidence that UCoGe is a p-wave superconductor and argue that superconductivity is mediated by critical ferromagnetic spin fluctuations., Comment: 19 pages; review paper; accepted for publication in the Journal of Low Temperature Physics (Special issue: Quantum Phase Transitions 2010)
Published: 2010
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39. Measurement of the atmospheric muon charge ratio with the OPERA detector

Author: OPERA Collaboration, Agafonova, N., Anokhina, A., Aoki, S., Ariga, A., Ariga, T., Autiero, D., Badertscher, A., Bagulya, A., Bertolin, A., Besnier, M., Bick, D., Boyarkin, V., Bozza, C., Brugière, T., Brugnera, R., Brunetti, G., Buontempo, S., Cazes, A., Chaussard, L., Chernyavsky, M., Chiarella, V., Chon-Sen, N., Chukanov, A., Cozzi, M., D'Amato, G., Corso, F. Dal, D'Ambrosio, N., De Lellis, G., D'eclais, Y., De Serio, M., Di Capua, F., Di Ferdinando, D., Di Giovanni, A., Di Marco, N., Dmitrievski, S., Dracos, M., Duchesneau, D., Dusini, S., Ebert, J., Egorov, O., Enikeev, R., Ereditato, A., Esposito, L. S., Favier, J., Felici, G., Ferber, T., Fini, R., Frekers, D., Fukuda, T., Fukushima, C., Galkin, V. I., Garfagnini, A., Giacomelli, G., Giorgini, M., Goellnitz, C., Goldberg, J., Golubkov, D., Goncharova, L., Gornushkin, Y., Grella, G., Grianti, F., Guler, M., Gustavino, C., Hagner, C., Hamada, K., Hara, T., Hierholzer, M., Hoshino, K., Ieva, M., Jakovcic, K., Jollet, C., Juget, F., Kazuyama, M., Kim, S. H., Kimura, M., Klicek, B., Knuesel, J., Kodama, K., Komatsu, M., Kose, U., Kreslo, I., Kubota, H., Lazzaro, C., Lenkeit, J., Ljubicic, A., Longhin, A., Lutter, G., Malgin, A., Mandrioli, G., Marotta, A., Marteau, J., Matsuo, T., Matveev, V., Mauri, N., Medinaceli, E., Meisel, F., Meregaglia, A., Migliozzi, P., Mikado, S., Miyamoto, S., Monacelli, P., Morishima, K., Moser, U., Muciaccia, M. T., Naganawa, N., Naka, T., Nakamura, M., Nakano, T., Naumov, D., Nikitina, V., Niwa, K., Nonoyama, Y., Ogawa, S., Olchevski, A., Oldorf, C., Orlova, G., Osedlo, V., Paniccia, M., Paoloni, A., Park, B. D., Park, I. G., Pastore, A., Patrizii, L., Pennacchio, E., Pessard, H., Pilipenko, V., Pistillo, C., Policastro, G., Polukhina, N., Pozzato, M., Pretzl, K., Publichenko, P., Pupilli, F., Rescigno, R., Roganova, T., Rokujo, H., Romano, G., Rosa, G., Rostovtseva, I., Rubbia, A., Russo, A., Ryasny, V., Ryazhskaya, O., Sato, O., Sato, Y., Schembri, A., Parzefall, W. Schmidt, Schroeder, H., Lavina, L. Scotto, Sheshukov, A., Shibuya, H., Simone, S., Sioli, M., Sirignano, C., Sirri, G., Song, J. S., Spinetti, M., Stanco, L., Starkov, N., Stipcevic, M., Strauss, T., Strolin, P., Takahashi, S., Tenti, M., Terranova, F., Tezuka, I., Tioukov, V., Tolun, P., Tran, T., Tufanli, S., Vilain, P., Vladimirov, M., Votano, L., Vuilleumier, J. L., Wilquet, G., Wonsak, B., Yakushev, V., Yoon, C. S., Yoshioka, T., Yoshida, J., Zaitsev, Y., Zemskova, S., Zghiche, A., and Zimmermann, R.
Subjects: High Energy Physics - Experiment
Abstract: The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio in the TeV energy region. We analyzed 403069 atmospheric muons corresponding to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the charge ratio dependence on the primary composition. The measured charge ratio values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the "vertical surface energy". A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum., Comment: 14 pages, 10 figures
Published: 2010

40. The case for a directional dark matter detector and the status of current experimental efforts

Author: Ahlen, S., Afshordi, N., Battat, J. B. R., Billard, J., Bozorgnia, N., Burgos, S., Caldwell, T., Carmona, J. M., Cebrian, S., Colas, P., Dafni, T., Daw, E., Dujmic, D., Dushkin, A., Fedus, W., Ferrer, E., Finkbeiner, D., Fisher, P. H., Forbes, J., Fusayasu, T., Galan, J., Gamble, T., Ghag, C., Giomataris, I., Gold, M., Gomez, H., Gomez, M. E., Gondolo, P., Green, A., Grignon, C., Guillaudin, O., Hagemann, C., Hattori, K., Henderson, S., Higashi, N., Ida, C., Iguaz, F. J., Inglis, A., Irastorza, I. G., Iwaki, S., Kaboth, A., Kabuki, S., Kadyk, J., Kallivayalil, N., Kubo, H., Kurosawa, S., Kudryavtsev, V. A., Lamy, T., Lanza, R., Lawson, T. B., Lee, A., Lee, E. R., Lin, T., Loomba, D., Lopez, J., Luzon, G., Manobu, T., Martoff, J., Mayet, F., Mccluskey, B., Miller, E., Miuchi, K., Monroe, J., Morgan, B., Muna, D., Murphy, A. St. J., Naka, T., Nakamura, K., Nakamura, M., Nakano, T., Nicklin, G. G., Nishimura, H., Niwa, K., Paling, S. M., Parker, J., Petkov, A., Pipe, M., Pushkin, K., Robinson, M., Rodriguez, A., Rodriguez-Quintero, J., Sahin, T., Sanderson, R., Sanghi, N., Santos, D., Sato, O., Sawano, T., Sciolla, G., Sekiya, H., Slatyer, T. R., Snowden-Ifft, D. P., Spooner, N. J. C., Sugiyama, A., Takada, A., Takahashi, M., Takeda, A., Tanimori, T., Taniue, K., Tomas, A., Tomita, H., Tsuchiya, K., Turk, J., Tziaferi, E., Ueno, K., Vahsen, S., Vanderspek, R., Vergados, J., Villar, J. A., Wellenstein, H., Wolfe, I., Yamamoto, R. K., and Yegoryan, H.
Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present the case for a dark matter detector with directional sensitivity. This document was developed at the 2009 CYGNUS workshop on directional dark matter detection, and contains contributions from theorists and experimental groups in the field. We describe the need for a dark matter detector with directional sensitivity; each directional dark matter experiment presents their project's status; and we close with a feasibility study for scaling up to a one ton directional detector, which would cost around $150M., Comment: 48 pages, 37 figures, whitepaper on direct dark matter detection with directional sensitivity
Published: 2009
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41. Enhancement of superconductivity near the ferromagnetic quantum critical point in UCoGe

Author: Slooten, E., Naka, T., Gasparini, A., Huang, Y. K., and de Visser, A.
Subjects: Condensed Matter - Superconductivity, Condensed Matter - Strongly Correlated Electrons
Abstract: We report a high-pressure single crystal study of the superconducting ferromagnet UCoGe. Ac-susceptibility and resistivity measurements under pressures up to 2.2 GPa show ferromagnetism is smoothly depressed and vanishes at a critical pressure $p_c = 1.4$ GPa. Near the ferromagnetic critical point superconductivity is enhanced. Upper-critical field measurements under pressure show $B_{c2}(0)$ attains remarkably large values, which provides solid evidence for spin-triplet superconductivity over the whole pressure range. The obtained $p-T$ phase diagram reveals superconductivity is closely connected to a ferromagnetic quantum critical point hidden under the superconducting `dome'., Comment: 4 pages, 3 figures; accepted for publication in PRL
Published: 2009
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42. Ordered magnetic and quadrupolar states under hydrostatic pressure in orthorhombic PrCu2

Author: Naka, T., Ponomarenko, L. A., de Visser, A., Matsushita, A., Settai, R., and Onuki, Y.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: We report magnetic susceptibility and electrical resistivity measurements on single-crystalline PrCu2 under hydrostatic pressure, up to 2 GPa, which pressure range covers the pressure-induced Van Vleck paramagnet-to-antiferromagnet transition at 1.2 GPa. The measured anisotropy in the susceptibility shows that in the pressure-induced magnetic state the ordered 4f-moments lie in the ac-plane. We propose that remarkable pressure effects on the susceptibility and resistivity are due to changes in the quadrupolar state of O22 and/or O20 under pressure. We present a simple analysis in terms of the singlet-singlet model., Comment: 14 pages, 9 figures submitted to Phys. Rev. B
Published: 2004
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43. High pressure transport study of non-Fermi liquid behaviour in U2Pt2In and U3Ni3Sn4

Author: de Visser, A., Estrela, P., and Naka, T.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: The strongly correlated metals U2Pt2In and U3Ni3Sn4 show pronounced non-Fermi liquid (NFL) phenomena at ambient pressure. Here we review single-crystal electrical resistivity measurements under pressure (p <= 1.8 GPa) conducted to investigate the stability of the NFL phase. For tetragonal U2Pt2In (I||a) we observe a rapid recovery of the Fermi-liquid T^2-term with pressure. The Fermi-liquid temperature varies as T_FL ~ p-p_c, where p_c= 0 is a critical pressure. The analysis within the magnetotransport theory of Rosch provides evidence for the location of U2Pt2In at a zero pressure antiferromagnetic quantum critical point (QCP). In the case of cubic U3Ni3Sn4 we find T_FL ~ (p-p_c)^1/2. The analysis provides evidence for an antiferromagnetic QCP in U3Ni3Sn4 at a negative pressure p_c= -0.04+-0.04 GPa., Comment: 6 pages (4 figures); to appear in Proc. of Int. Conf. PPHMF-IV (20-25 Oct. 2001, Santa Fe)
Published: 2001
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44. Pressure-induced recovery of the Fermi-liquid state in the non-Fermi liquid material U2Pt2In

Author: Estrela, P., de Visser, A., Naka, T., de Boer, F. R., and Pereira, L. C. J.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: In the study of non-Fermi-liquid (NFL) phenomena in correlated metals, U2Pt2In is of special interest as it is one of the rare stoichiometric (undoped) materials that show NFL behaviour at ambient pressure. Here we report on the stability of the NFL phase with respect to hydrostatic pressure (p< 1.8 GPa). Electrical resistivity data under pressure, taken on a single-crystalline sample for a current in the tetragonal plane, show that T_FL, i.e. the temperature below which the Fermi-liquid T^2-term is observed, increases with pressure as T_FL ~ (p-p_c), where p_c~0 is a critical pressure. This provides strong evidence for the location of U2Pt2In at an antiferromagnetic quantum critical point., Comment: 7 pages (including 2 figures); pdf format; short paper submitted to the Proceedings of SCES2001
Published: 2001
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45. Recovery of the Fermi-liquid state in U_3Ni_3Sn_4 by pressure

Author: Estrela, P., de Visser, A., de Boer, F. R., Naka, T., and Shlyk, L.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: Measurements of the resistivity of single-crystalline U_3Ni_3Sn_4 under hydrostatic pressure up to 1.8 GPa are reported. We show that the temperature T_FL, below which the resistivity obeys the Fermi-liquid expression rho ~ T^2, increases with pressure as T_FL ~ (p-p_c)^1/2. The analysis of the data within the magnetotransport theory of Rosch lends strong support for an antiferromagnetic quantum critical point in U_3Ni_3Sn_4 at a negative critical pressure p_c of -0.04+-0.02 GPa. The proximity to an antiferromagnetic instability in U_3Ni_3Sn_4 is consistent with the previously reported non-Fermi liquid term in the low-temperature specific heat., Comment: 14 pages (including 4 figures); pdf format
Published: 2000
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46. High-pressure study of the non-Fermi liquid material U_2Pt_2In

Author: Estrela, P., de Visser, A., Naka, T., de Boer, F. R., and Pereira, L. C. J.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: The effect of hydrostatic pressure (p<= 1.8 GPa) on the non-Fermi liquid state of U_2Pt_2In is investigated by electrical resistivity measurements in the temperature interval 0.3-300 K. The experiments were carried out on single-crystals with the current along (I||c) and perpendicular (I||a) to the tetragonal axis. The pressure effect is strongly current-direction dependent. For I||a we observe a rapid recovery of the Fermi-liquid T^2-term with pressure. The low-temperature resistivity can be analysed satisfactorily within the magnetotransport theory of Rosch, which provides strong evidence for the location of U_2Pt_2In at an antiferromagnetic quantum critical point. For I||c the resistivity increases under pressure, indicating the enhancement of an additional scattering mechanism. In addition, we have measured the pressure dependence of the antiferromagnetic ordering temperature (T_N= 37.6 K) of the related compound U_2Pd_2In. A simple Doniach-type diagram for U_2Pt_2In and U_2Pd_2In under pressure is presented., Comment: 21 pages (including 5 figures); pdf format
Published: 2000
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47. Resistivity of non-Fermi liquid U2Pt2In under pressure

Author: Estrela, P., Naka, T., de Visser, A., de Boer, F. R., Pereira, L. C. J., and Almeida, M.
Subjects: Condensed Matter - Strongly Correlated Electrons
Abstract: Non-Fermi liquid behaviour in single-crystalline U2Pt2In has been studied by means of resistivity experiments (I||c) under hydrostatic pressure (P<1.5 GPa). At ambient pressure the resistivity rho(T) follows a power law rho~T^alpha with alpha~0.5. Upon applying pressure alpha increases. For P>1 GPa a minimum develops in rho(T). A study of the field dependence of the minimum confirms its magnetic origin. The ratio c/a is proposed as the effective control parameter, rather than the unit cell volume., Comment: 5 pages (incl. 2 figures), submitted to SCES'99, Nagano
Published: 1999
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48. Directional sensitivity of the NEWSdm experiment to cosmic ray boosted dark matter

Author: Agafonova, N.Y., primary, Alexandrov, A., additional, Anokhina, A.M., additional, Asada, T., additional, Ashikhmin, V.V., additional, Boccia, V., additional, Centanni, D., additional, Chernyavskii, M.M., additional, Chin, N., additional, D'Ambrosio, N., additional, De Lellis, G., additional, Di Crescenzo, A., additional, Dowdy, Y.C., additional, Dmitrievski, S., additional, Enikeev, R.I., additional, Galati, G., additional, Galkin, V.I., additional, Golovatiuk, A., additional, Gorbunov, S.A., additional, Gornushkin, Y., additional, Guler, A.M., additional, Gulyaeva, V.V., additional, Iuliano, A., additional, Khalikov, E.V., additional, Kim, S.H., additional, Konovalova, N.S., additional, Krasilnikova, Y.O., additional, Lauria, A., additional, Lee, K.Y., additional, Loschiavo, V.P., additional, Managadze, A.K., additional, Miloi, A., additional, Montesi, M.C., additional, Naka, T., additional, Okateva, N.M., additional, Park, B.D., additional, Podgrudkov, D.A., additional, Polukhina, N.G., additional, Roganova, T.M., additional, Rosa, G., additional, Samoilov, M.A., additional, Sadykov, Z.T., additional, Sadovsky, A., additional, Saeki, K., additional, Sato, O., additional, Shakiryanova, I.R., additional, Shchedrina, T.V., additional, Shiraishi, T., additional, Sohn, J.Y., additional, Sotnikov, A., additional, Starkov, N.I., additional, Starkova, E.N., additional, Strekalina, D.M., additional, Tioukov, V., additional, Ursov, E.D., additional, Ustyuzhanin, A., additional, Vasina, S., additional, Voronkov, R.A., additional, and Yoon, C.S., additional
Published: 2023
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49. Relation between UIS withstanding capability and I-V characteristics in high-voltage GaN-HEMTs

Author: Saito, W. and Naka, T.
Published: 2017
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50. WIMP tracking with cryogenic nuclear emulsion

Author: Kimura, M., Naka, T., Furuya, S., Asada, T., Katsuragawa, T., Yoshimoto, M., Umemoto, A., Machii, S., Ichiki, H., Sato, O., and Hoshino, Y.
Published: 2017
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