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1. Neutron-antineutron oscillation search using a 0.37 megaton-years exposure of Super-Kamiokande

Author

Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Imaizumi, S, Ito, H, Kameda, J, Kataoka, Y, Miura, M, Moriyama, S, Nagao, Y, Nakahata, M, Nakajima, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Suzuki, Y, Takeda, A, Takemoto, Y, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Han, S, Kajita, T, Okumura, K, Tashiro, T, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Marti, Ll, Zaldivar, B, Blaszczyk, FDM, Kearns, E, Gustafson, JD, Raaf, JL, Stone, JL, Wan, L, Wester, T, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Coffani, A, Drapier, O, Hedri, S El, Giampaolo, A, Gonin, M, Mueller, Th A, Paganini, P, Quilain, B, Ishizuka, T, Nakamura, T, Jang, JS, Learned, JG, Anthony, LHV, Sztuc, AA, Uchida, Y, Berardi, V, Catanesi, MG, Radicioni, E, Calabria, NF, Machado, LN, De Rosa, G, Collazuol, G, Iacob, F, Lamoureux, M, Ospina, N, Ludovici, L, Nishimura, Y, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Matsubara, T, Nakadaira, T, Jakkapu, M, Nakamura, K, Oyama, Y, Sakashita, K, and Sekiguchi, T

Subjects
Nuclear and Plasma Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

As a baryon number violating process with ΔB=2, neutron-antineutron oscillation (n→n¯) provides a unique test of baryon number conservation. We have performed a search for n→n¯ oscillation with bound neutrons in Super-Kamiokande, with the full dataset from its first four run periods, representing an exposure of 0.37 Mton-years. The search used a multivariate analysis trained on simulated n→n¯ events and atmospheric neutrino backgrounds and resulted in 11 candidate events with an expected background of 9.3 events. In the absence of statistically significant excess, we derived a lower limit on n¯ appearance lifetime in O16 nuclei of 3.6×1032 years and on the neutron-antineutron oscillation time of τn→n¯>4.7×108 s at 90% C.L.

Published
2021

2. Search for proton decay via p→e+π0 and p→μ+π0 with an enlarged fiducial volume in Super-Kamiokande I-IV

Author

Takenaka, A, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Imaizumi, S, Ito, H, Kameda, J, Kataoka, Y, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nagao, Y, Nakahata, M, Nakajima, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Suzuki, Y, Takeda, A, Takemoto, Y, Tanaka, H, Yano, T, Akutsu, R, Han, S, Kajita, T, Okumura, K, Tashiro, T, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Fernandez, P, Zaldivar, B, Blaszczyk, FDM, Kearns, E, Raaf, JL, Stone, JL, Wan, L, Wester, T, Pointon, BW, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Coffani, A, Drapier, O, Hedri, S El, Giampaolo, A, Gonin, M, Mueller, Th A, Paganini, P, Quilain, B, Ishizuka, T, Nakamura, T, Jang, JS, Learned, JG, Matsuno, S, Anthony, LHV, Litchfield, RP, Sztuc, AA, Uchida, Y, Berardi, V, Catanesi, MG, Radicioni, E, Calabria, NF, Machado, LN, De Rosa, G, Collazuol, G, Iacob, F, Lamoureux, M, Ospina, N, Ludovici, L, Nishimura, Y, Cao, S, Friend, M, Hasegawa, T, Ishida, T, and Jakkapu, M

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

We have searched for proton decay via p→e+π0 and p→μ+π0 modes with the enlarged fiducial volume data of Super-Kamiokande from April 1996 to May 2018, which corresponds to 450 kton·years exposure. We have accumulated about 25% more livetime and enlarged the fiducial volume of the Super-Kamiokande detector from 22.5 kton to 27.2 kton for this analysis, so that 144 kton·years of data, including 78 kton·years of additional fiducial volume data, has been newly analyzed. No candidates have been found for p→e+π0 and one candidate remains for p→μ+π0 in the conventional 22.5 kton fiducial volume and it is consistent with the atmospheric neutrino background prediction. We set lower limits on the partial lifetime for each of these modes: τ/B(p→e+π0)>2.4×1034 years and τ/B(p→μ+π0)>1.6×1034 years at 90% confidence level.

Published
2020

3. Indirect search for dark matter from the Galactic Center and halo with the Super-Kamiokande detector

Author

Abe, K, Bronner, C, Haga, Y, Hayato, Y, Ikeda, M, Imaizumi, S, Ito, H, Iyogi, K, Kameda, J, Kataoka, Y, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nagao, Y, Nakahata, M, Nakajima, Y, Nakajima, T, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Tasaka, S, Tomura, T, Ueno, K, Yano, T, Yokozawa, T, Akutsu, R, Han, S, Irvine, T, Kajita, T, Kametani, I, Lee, KP, McLachlan, T, Okumura, K, Richard, E, Tashiro, T, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Fernandez, P, Blaszczyk, FDM, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Sussman, S, Wan, L, Wester, T, Berkman, S, Tobayama, S, Bian, J, Carminati, G, Elnimr, M, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Renshaw, A, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Hartfiel, BL, Hill, J, Keig, WE, Hong, N, Kim, JY, Lim, IT, Park, RG, Akiri, T, Bodur, B, Himmel, A, Li, Z, O’Sullivan, E, Scholberg, K, Walter, CW, Wongjirad, T, Coffani, A, Drapier, O, Hedri, S El, Giampaolo, A, Gonin, M, Imber, J, Mueller, Th A, Paganini, P, Quilain, B, and Ishizuka, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

We present a search for an excess of neutrino interactions due to dark matter in the form of weakly interacting massive particles (WIMPs) annihilating in the Galactic center or halo based on the data set of Super-Kamiokande-I, -II, -III and -IV taken from 1996 to 2016. We model the neutrino flux, energy, and flavor distributions assuming WIMP self-annihilation is dominant to νν¯, μ+μ-, bb¯, or W+W-. The excess is in comparison to atmospheric neutrino interactions which are modeled in detail and fit to data. Limits on the self-annihilation cross section σ are derived for WIMP masses in the range 1 GeV to 10 TeV, reaching as low as 9.6×10-23 cm3 s-1 for 5 GeV WIMPs in bb¯ mode and 1.2×10-24 cm3 s-1 for 1 GeV WIMPs in νν¯ mode. The obtained sensitivity of the Super-Kamiokande detector to WIMP masses below several tens of GeV is the best among similar indirect searches to date.

Published
2020

4. Search for proton decay into three charged leptons in 0.37 megaton-years exposure of the Super-Kamiokande

Author

Tanaka, M, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Imaizumi, S, Ito, H, Kameda, J, Kataoka, Y, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nakahata, M, Nakajima, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Okumura, K, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Fernandez, P, Blaszczyk, FDM, Kearns, E, Raaf, JL, Stone, JL, Wan, L, Wester, T, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Coffani, A, Drapier, O, Hedri, S El, Gonin, M, Mueller, Th A, Paganini, P, Ishizuka, T, Nakamura, T, Jang, JS, Learned, JG, Matsuno, S, Litchfield, RP, Sztuc, AA, Uchida, Y, Berardi, V, Catanesi, MG, Radicioni, E, Calabria, NF, De Rosa, G, Collazuol, G, Iacob, F, Ludovici, L, Nishimura, Y, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Hasegawa, M, Isobe, Y, Miyabe, H, Nakano, Y, Shiozawa, T, Sugimoto, T, and Suzuki, AT

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

A search for proton decay into three charged leptons has been performed by using 0.37 Mton·years of data collected in Super-Kamiokande. All possible combinations of electrons, muons, and their antiparticles consistent with charge conservation were considered as decay modes. No significant excess of events has been found over the background, and lower limits on the proton lifetime divided by the branching ratio have been obtained. The limits range between 9.2×1033 and 3.4×1034 years at 90% confidence level, improving by more than an order of magnitude upon limits from previous experiments. A first limit has been set for the p→μ-e+e+ mode.

Published
2020

5. Search for Astronomical Neutrinos from Blazar TXS 0506+056 in Super-Kamiokande

Author

Hagiwara, K, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Ito, H, Kameda, J, Kataoka, Y, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nakahata, M, Nakajima, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Okumura, K, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Fernandez, P, Blaszczyk, FDM, Kearns, E, Raaf, JL, Stone, JL, Wan, L, Wester, T, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Coffani, A, Drapier, O, Gonin, M, Mueller, Th A, Paganini, P, Ishizuka, T, Nakamura, T, Jang, JS, Learned, JG, Matsuno, S, Litchfield, RP, Sztuc, AA, Uchida, Y, Berardi, V, Calabria, NF, Catanesi, MG, Radicioni, E, De Rosa, G, Collazuol, G, Iacob, F, Ludovici, L, Nishimura, Y, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Hasegawa, M, Isobe, Y, Miyabe, H, Nakano, Y, Shiozawa, T, Sugimoto, T, Suzuki, AT, and Takeuchi, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, astro-ph.HE, Astronomical and Space Sciences, Astronomy & Astrophysics, Astronomical sciences, Space sciences
Abstract

We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron-and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10-7 and 4.5 × 10-7-9.3 × 10-10 [erg cm-2 s-1], respectively.

Published
2019

6. Sensitivity of Super-Kamiokande with Gadolinium to Low Energy Antineutrinos from Pre-supernova Emission

Author

Simpson, C, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Ito, H, Iyogi, K, Kameda, J, Kataoka, Y, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nakahata, M, Nakajima, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Okumura, K, Wang, R, Xia, J, Bravo-Berguño, D, Labarga, L, Fernandez, P, Blaszczyk, FDM, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Wan, L, Wester, T, Sussman, S, Berkman, S, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Smy, MB, Sobel, HW, Takhistov, V, Weatherly, P, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Coffani, A, Drapier, O, Gonin, M, Imber, J, Mueller, Th A, Paganini, P, Ishizuka, T, Nakamura, T, Jang, JS, Choi, K, Learned, JG, Matsuno, S, Litchfield, RP, Sztuc, AA, Uchida, Y, Wascko, MO, Berardi, V, Calabria, NF, Catanesi, MG, Intonti, RA, Radicioni, E, De Rosa, G, Collazuol, G, Iacob, F, Ludovici, L, Nishimura, Y, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, and Tsukamoto, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Neutrino astronomy, Supernova neutrinos, Particle astrophysics, Silicon burning, astro-ph.HE, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

Supernova detection is a major objective of the Super-Kamiokande (SK) experiment. In the next stage of SK (SK-Gd), gadolinium (Gd) sulfate will be added to the detector, which will improve the ability of the detector to identify neutrons. A core-collapse supernova (CCSN) will be preceded by an increasing flux of neutrinos and antineutrinos, from thermal and weak nuclear processes in the star, over a timescale of hours; some of which may be detected at SK-Gd. This could provide an early warning of an imminent CCSN, hours earlier than the detection of the neutrinos from core collapse. Electron antineutrino detection will rely on inverse beta decay events below the usual analysis energy threshold of SK, so Gd loading is vital to reduce backgrounds while maximizing detection efficiency. Assuming normal neutrino mass ordering, more than 200 events could be detected in the final 12 hr before core collapse for a 15-25 solar mass star at around 200 pc, which is representative of the nearest red supergiant to Earth, α-Ori (Betelgeuse). At a statistical false alarm rate of 1 per century, detection could be up to 10 hr before core collapse, and a pre-supernova star could be detected by SK-Gd up to 600 pc away. A pre-supernova alert could be provided to the astrophysics community following gadolinium loading.

Published
2019

7. Atmospheric neutrino oscillation analysis with improved event reconstruction in Super-Kamiokande IV

Author

Jiang, M, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kato, Y, Kishimoto, Y, Marti, LL, Miura, M, Moriyama, S, Mochizuki, T, Nakahata, M, Nakajima, Y, Nakano, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Nishimura, Y, Okumura, K, Wang, R, Xia, J, Labarga, L, Fernandez, P, Blaszczyk, FDM, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sussman, S, Berkman, S, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Weatherly, P, Smy, MB, Sobel, HW, Takhistov, V, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Gonin, M, Imber, J, Mueller, Th A, Ishizuka, T, Nakamura, T, Jang, JS, Choi, K, Learned, JG, Matsuno, S, Litchfield, RP, Uchida, Y, Wascko, MO, Calabria, NF, Catanesi, MG, Intonti, RA, Radicioni, E, De Rosa, G, Ali, A, Collazuol, G, Iacob, F, Ludovici, L, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Abe, KE, Hasegawa, M, Isobe, Y, Miyabe, H, Sugimoto, T, Suzuki, AT, Takeuchi, Y, and Ashida, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Mathematical Sciences
Abstract

A new event reconstruction algorithm based on a maximum likelihood method has been developed for Super-Kamiokande. Its improved kinematic and particle identification capabilities enable the analysis of atmospheric neutrino data in a detector volume 32% larger than previous analyses and increase the sensitivity to the neutrino mass hierarchy.Analysis of a 253.9 kton•year exposure of the Super-Kamiokande IV atmospheric neutrino data has yielded a weak preference for the normal hierarchy, disfavoring the inverted hierarchy at 74% assuming oscillations at the best fit of the analysis.

Published
2019

8. Measurement of the neutrino-oxygen neutral-current quasielastic cross section using atmospheric neutrinos at Super-Kamiokande

Author

Wan, L, Abe, K, Bronner, C, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kato, Y, Kishimoto, Y, Marti, Ll, Miura, M, Moriyama, S, Mochizuki, T, Nakahata, M, Nakajima, Y, Nakano, Y, Nakayama, S, Okada, T, Okamoto, K, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Yano, T, Akutsu, R, Kajita, T, Nishimura, Y, Okumura, K, Wang, R, Xia, J, Labarga, L, Fernandez, P, Blaszczyk, FDM, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sussman, S, Berkman, S, Bian, J, Griskevich, NJ, Kropp, WR, Locke, S, Mine, S, Weatherly, P, Smy, MB, Sobel, HW, Takhistov, V, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Park, RG, Bodur, B, Scholberg, K, Walter, CW, Gonin, M, Imber, J, Mueller, Th A, Ishizuka, T, Nakamura, T, Jang, JS, Choi, K, Learned, JG, Matsuno, S, Litchfield, RP, Uchida, Y, Wascko, MO, Calabria, NF, Catanesi, MG, Intonti, RA, Radicioni, E, De Rosa, G, Ali, A, Collazuol, G, Iacob, F, Ludovici, L, Cao, S, Friend, M, Hasegawa, T, Ishida, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Abe, KE, Hasegawa, M, Isobe, Y, Miyabe, H, Sugimoto, T, Suzuki, AT, Takeuchi, Y, and Ashida, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

Neutral current (NC) interactions of atmospheric neutrinos on oxygen form one of the major backgrounds in the search for supernova relic neutrinos with water-based Cherenkov detectors. The NC channel is dominated by neutrino quasielastic (NCQE) scattering off nucleons inside O16 nuclei. In this paper we report the first measurement of NCQE cross section using atmospheric neutrinos at Super-Kamiokande (SK). The measurement used 2,778 live days of SK-IV data with a fiducial volume of 22.5 kiloton water. Within the visible energy window of 7.5-29.5 MeV, we observed 117 events compared to the expected 71.9 NCQE signal and 53.1 background events. Weighted by the atmospheric neutrino spectrum from 160 MeV to 10 GeV, the flux averaged NCQE cross section is measured to be (1.01±0.17(stat.)-0.30+0.78(sys.))×10-38 cm2.

Published
2019

9. Search for n-n ¯ oscillation in Super-Kamiokande SEARCH FOR n-n ¯ OSCILLATION IN SUPER-⋯ K. ABE et al.

Author

Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, and Itow, Y

Subjects
hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract

A search for neutron-antineutron (n-n¯) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or 2.45×1034 neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for n-n¯ oscillation was found; the lower limit of the lifetime for neutrons bound in O16, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9×1032years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7×108s using a theoretical value of the nuclear suppression factor of 0.517×1023s-1 and its uncertainty.

Published
2015

10. Search for dinucleon decay into pions at Super-Kamiokande

Author

Gustafson, J, Abe, K, Haga, Y, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kishimoto, Y, Miura, M, Moriyama, S, Nakahata, M, Nakajima, T, Nakano, Y, Nakayama, S, Orii, A, Sekiya, H, Shiozawa, M, Takeda, A, Tanaka, H, Tomura, T, Wendell, RA, Irvine, T, Kajita, T, Kametani, I, Kaneyuki, K, Nishimura, Y, Richard, E, Okumura, K, Labarga, L, Fernandez, P, Berkman, S, Tanaka, HA, Tobayama, S, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Goldhaber, M, Carminati, G, Kropp, WR, Mine, S, Weatherly, P, Renshaw, A, Smy, MB, Sobel, HW, Takhistov, V, Ganezer, KS, Hartfiel, BL, Hill, J, Hong, N, Kim, JY, Lim, IT, Akiri, T, Himmel, A, Scholberg, K, Walter, CW, Wongjirad, T, Ishizuka, T, Tasaka, S, Jang, JS, Learned, JG, Matsuno, S, Smith, SN, Hasegawa, T, Ishida, T, Ishii, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Suzuki, AT, Takeuchi, Y, Yano, T, Hirota, S, Huang, K, Ieki, K, Kikawa, T, Minamino, A, Nakaya, T, Suzuki, K, Takahashi, S, Fukuda, Y, Choi, K, Itow, Y, Mitsuka, G, Suzuki, T, Mijakowski, P, Hignight, J, Imber, J, Jung, CK, Palomino, JL, Yanagisawa, C, Ishino, H, Kayano, T, Kibayashi, A, Koshio, Y, and Mori, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Super-Kamiokande Collaboration, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

A search for the dinucleon decay pp → K+ K+ has been performed using 91.6  kton·yr data from Super-Kamiokande-I. This decay provides a sensitive probe of the R-parity-violating parameter λ112''. A boosted decision tree analysis found no signal candidates in the data. The expected background was 0.28±0.19 atmospheric neutrino induced events and the estimated signal detection efficiency was 12.6%±3.2%. A lower limit of 1.7×10(32)  years has been placed on the partial lifetime of the decay O16 → C14K+ K+ at 90% C.L. A corresponding upper limit of 7.8×10(-9) has been placed on the parameter λ112''.

Published
2015

11. Search for n−n¯ oscillation in Super-Kamiokande

Author

Abe, K, Hayato, Y, Iida, T, Ishihara, K, Kameda, J, Koshio, Y, Minamino, A, Mitsuda, C, Miura, M, Moriyama, S, Nakahata, M, Obayashi, Y, Ogawa, H, Sekiya, H, Shiozawa, M, Suzuki, Y, Takeda, A, Takeuchi, Y, Ueshima, K, Watanabe, H, Higuchi, I, Ishihara, C, Ishitsuka, M, Kajita, T, Kaneyuki, K, Mitsuka, G, Nakayama, S, Nishino, H, Okumura, K, Saji, C, Takenaga, Y, Clark, S, Desai, S, Dufour, F, Herfurth, A, Kearns, E, Likhoded, S, Litos, M, Raaf, JL, Stone, JL, Sulak, LR, Wang, W, Goldhaber, M, Casper, D, Cravens, JP, Dunmore, J, Griskevich, J, Kropp, WR, Liu, DW, Mine, S, Regis, C, Smy, MB, Sobel, HW, Vagins, MR, Ganezer, KS, Hartfiel, B, Hill, J, Keig, WE, Jang, JS, Jeoung, IS, Kim, JY, Lim, IT, Scholberg, K, Tanimoto, N, Walter, CW, Wendell, R, Ellsworth, RW, Tasaka, S, Guillian, G, Learned, JG, Matsuno, S, Messier, MD, Ichikawa, AK, Ishida, T, Ishii, T, Iwashita, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Nishikawa, K, Nitta, K, Oyama, Y, Suzuki, AT, Hasegawa, M, Maesaka, H, Nakaya, T, Sasaki, T, Sato, H, Tanaka, H, Yamamoto, S, Yokoyama, M, Haines, TJ, Dazeley, S, Hatakeyama, S, Svoboda, R, Sullivan, GW, Gran, R, Habig, A, Fukuda, Y, and Itow, Y

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

A search for neutron-antineutron (n-n¯) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or 2.45×1034 neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for n-n¯ oscillation was found; the lower limit of the lifetime for neutrons bound in O16, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be 1.9×1032years at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be 2.7×108s using a theoretical value of the nuclear suppression factor of 0.517×1023s-1 and its uncertainty.

Published
2015

12. Evaluation of gadolinium's action on water Cherenkov detector systems with EGADS

Author

Ikeda, M, Kato, Y, Kishimoto, Y, Marti, L, Nakahata, M, Nakajima, Y, Nakano, Y, Nakayama, S, Okajima, Y, Orii, A, Pronost, G, Sekiya, H, Shiozawa, M, Tanaka, H, Ueno, K, Yamada, S, Yano, T, Yokozawa, T, Murdoch, M, Schuemann, J, Vagins, MR, Bays, K, Carminati, G, Griskevich, NJ, Kropp, WR, Locke, S, Renshaw, A, Smy, MB, Weatherly, P, Ito, S, Ishino, H, Kibayashi, A, Koshio, Y, Mori, T, Sakuda, M, Yamaguchi, R, Fernandez, P, Labarga, L, Bandac, I, Perez, J, Amey, J, Litchfield, RP, Sztuc, A, Uchida, Y, Ma, WY, Goldsack, A, Simpson, C, Wark, D, Anthony, LHV, McCauley, N, Pritchard, A, Lodovico, FD, Richards, B, Cole, A, Thiesse, M, Thompson, L, Imber, J, Cao, SV, Ito, K, Takeuchi, Y, Akutsu, R, Nishimura, Y, Okumura, K, Hirota, S, Muto, F, Yokoyama, M, Suda, Y, Zhang, H, and Science and Technology Facilities Council (STFC)

Subjects
Physics::Instrumentation and Detectors, physics.ins-det
Abstract

Used for both proton decay searches and neutrino physics, large water Cherenkov (WC) detectors have been very successful tools in particle physics. They are notable for their large masses and charged particle detection capabilities. While current WC detectors reconstruct charged particle tracks over a wide energy range, they cannot efficiently detect neutrons. Gadolinium (Gd) has the largest thermal neutron capture cross section of all stable nuclei and produces an 8 MeV gamma cascade that can be detected with high efficiency. Because of the many new physics opportunities that neutron tagging with a Gd salt dissolved in water would open up, a large-scale R&D program called EGADS was established to demonstrate this technique's feasibility. EGADS features all the components of a WC detector, chiefly a 200-ton stainless steel water tank furnished with 240 photo-detectors, DAQ, and a water system that removes all impurities in water while keeping Gd in solution. In this paper we discuss the milestones towards demonstrating the feasibility of this novel technique, and the features of EGADS in detail.

Published
2019

13. Search for nucleon decay into charged antilepton plus meson in 0.316 megaton · years exposure of the Super-Kamiokande water Cherenkov detector

Author

Abe, K, Bronner, C, Pronost, G, Hayato, Y, Ikeda, M, Iyogi, K, Kameda, J, Kato, Y, Kishimoto, Y, Marti, L, Miura, M, Mine, S, Locke, S, Weatherly, P, Smy, MB, Sobel, HW, Takhistov, V, Ganezer, KS, Hill, J, Kim, JY, Lim, IT, Anthony, LHV, Park, RG, Himmel, A, Li, Z, O'Sullivan, E, Scholberg, K, Walter, CW, Ishizuka, T, Nakamura, T, Jang, JS, Choi, K, McCauley, N, Learned, JG, Matsuno, S, Smith, SN, Amey, J, Litchfield, RP, Ma, WY, Uchida, Y, Wascko, MO, Cao, S, Friend, M, Pritchard, A, Hasegawa, T, Ishida, T, Ishii, T, Kobayashi, T, Nakadaira, T, Nakamura, K, Oyama, Y, Sakashita, K, Sekiguchi, T, Tsukamoto, T, Fukuda, Y, Abe, KE, Hasegawa, M, Suzuki, AT, Takeuchi, Y, Yano, T, Hayashino, T, Hiraki, T, Hirota, S, Huang, K, Jiang, M, Itow, Y, Nakamura, KE, Nakaya, T, Quilain, B, Patel, ND, Wendell, RA, Murase, M, Muto, F, Mijakowski, P, Frankiewicz, K, Jung, CK, Moriyama, S, Li, X, Palomino, JL, Santucci, G, Vilela, C, Wilking, MJ, Yanagisawa, C, Ito, S, Fukuda, D, Ishino, H, Kibayashi, A, Nakahata, M, Koshio, Y, Nagata, H, Sakuda, M, Xu, C, Kuno, Y, Wark, D, Di Lodovico, F, Richards, B, Tacik, R, Kim, SB, Nakano, Y, Cole, A, Thompson, L, Okazawa, H, Choi, Y, Ito, K, Nishijima, K, Koshiba, M, Totsuka, Y, Suda, Y, Yokoyama, M, Nakayama, S, Calland, RG, Hartz, M, Martens, K, Shimpson, C, Suzuki, Y, Vagins, MR, Martin, JF, Nantais, CM, Tanaka, HA, Konaka, A, Okajima, Y, Chen, S, Wan, L, Zhang, Y, Minamino, A, Wilkes, RJ, Orii, A, Sekiya, H, Shiozawa, M, Sonoda, Y, Takeda, A, Takenaka, A, Tanaka, H, Tasaka, S, Tomura, T, Akutsu, R, Kajita, T, Kaneyuki, K, Nishimura, Y, Okumura, K, Tsui, KM, Labarga, L, Fernandez, P, Blaszczyk, FDM, Gustafson, J, Kachulis, C, Kearns, E, Raaf, JL, Stone, JL, Sulak, LR, Berkman, S, Tobayama, S, Goldhaber, M, Elnimr, M, Kropp, WR, and Science and Technology Facilities Council (STFC)

Subjects
Science & Technology, Physics, PIONS, Nuclear Theory, Astronomy & Astrophysics, RESONANCE, Physics, Particles & Fields, GRAND UNIFIED THEORIES, CROSS-SECTIONS, Physical Sciences, LEPTONS, PROTON LIFETIME, MODES, SCATTERING, SPECTRA, High Energy Physics::Experiment, Nuclear Experiment, TRUE ABSORPTION
Abstract

We have searched for proton decays into a charged antilepton ( e + , μ + ) plus a meson ( η , ρ 0 , ω ) and for neutron decays into a charged antilepton ( e + , μ + ) plus a meson ( π − , ρ − ) using Super-Kamiokande I-IV data, corresponding to 0.316 megaton ⋅ years of exposure. This measurement updates the previous published result by using 2.26 times more data and improved analysis methods. No significant evidence for nucleon decay is observed and lower limits on the partial lifetime of the nucleon are obtained. The limits range from 3 × 10 31 to 1 × 10 34 years at 90% confidence level, depending on the decay mode.

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