Details of a Researcher - NISHIMURA Yasuhiro

Papers - NISHIMURA Yasuhiro

Division display 61 - 80 of about 87 ／ All the affair displays >>

Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations

Abe K., Akutsu R., Ali A., Alt C., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Arihara T., Asada Y., Ashida Y., Atkin E.T., Awataguchi Y., Ban S., Barbi M., Barker G.J., Barr G., Barrow D., Barry C., Batkiewicz-Kwasniak M., Beloshapkin A., Bench F., Berardi V., Berkman S., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Berguño D.B., Bronner C., Bubak A., Avanzini M.B., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Cicerchia M., Christodoulou G., Coleman J., Collazuol G., Cook L., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Doyle T.A., Drapier O., Dumarchez J., Dunne P., Eguchi A., Eklund L., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda R., Fukuda Y., Fusshoeller K., Gameil K., Giganti C., Golan T., Gonin M., Gorin A., Guigue M., Hadley D.R., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hassani S., Hastings N.C., Hayashino T., Hayato Y.

Nature (Nature) 580 ( 7803 ) 339 - 344 2020.04

ISSN 00280836

The charge-conjugation and parity-reversal (CP) symmetry of fundamental particles is a symmetry between matter and antimatter. Violation of this CP symmetry was first observed in 19641, and CP violation in the weak interactions of quarks was soon established2. Sakharov proposed3 that CP violation is necessary to explain the observed imbalance of matter and antimatter abundance in the Universe. However, CP violation in quarks is too small to support this explanation. So far, CP violation has not been observed in non-quark elementary particle systems. It has been shown that CP violation in leptons could generate the matter–antimatter disparity through a process called leptogenesis4. Leptonic mixing, which appears in the standard model’s charged current interactions5,6, provides a potential source of CP violation through a complex phase δCP, which is required by some theoretical models of leptogenesis7–9. This CP violation can be measured in muon neutrino to electron neutrino oscillations and the corresponding antineutrino oscillations, which are experimentally accessible using accelerator-produced beams as established by the Tokai-to-Kamioka (T2K) and NOvA experiments10,11. Until now, the value of δCP has not been substantially constrained by neutrino oscillation experiments. Here we report a measurement using long-baseline neutrino and antineutrino oscillations observed by the T2K experiment that shows a large increase in the neutrino oscillation probability, excluding values of δCP that result in a large increase in the observed antineutrino oscillation probability at three standard deviations (3σ). The 3σ confidence interval for δCP, which is cyclic and repeats every 2π, is [−3.41, −0.03] for the so-called normal mass ordering and [−2.54, −0.32] for the inverted mass ordering. Our results indicate CP violation in leptons and our method enables sensitive searches for matter–antimatter asymmetry in neutrino oscillations using accelerator-produced neutrino beams. Future measurements with larger datasets will test whether leptonic CP violation is larger than the CP violation in quarks.

Access to Document (DOI)

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

Marti L., Ikeda M., Kato Y., Kishimoto Y., 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 M.R., Bays K., Carminati G., Griskevich N.J., Kropp W.R., Locke S., Renshaw A., Smy M.B., 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 R.P., Sztuc A., Uchida Y., Ma W.Y., Goldsack A., Simpson C., Wark D., Anthony L.H.V., McCauley N., Pritchard A., Di Lodovico F., Richards B., Cole A., Thiesse M., Thompson L., Imber J., Cao S.V., Ito K., Takeuchi Y., Akutsu R., Nishimura Y., Okumura K., Hirota S., Muto F., Yokoyama M., Suda Y., Zhang H.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment (Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment) 959 2020.04

ISSN 01689002

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 from 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.

Access to Document (DOI)

New large aperture photodetectors for water Cherenkov detectors

Nishimura Y.

ISSN 01689002

New 50cm-diameter photo-detectors based on three different types of amplification systems were developed for future large water Cherenkov detectors. The R12860 PMT, based on a box-and-line dynode, was developed with Hamamatsu Photonics K.K. (Hamamatsu). Its detection efficiency is twice that of a conventional 50 cm PMT, while also improving by a factor two the charge and timing resolutions and being able to resist pressures up to 1.25MPa. A 50 cm hybrid photo-detector (HPD) using an avalanche diode (Hamamatsu, R12850) realized further improvement on the resolutions by the successful development of a preamplifier. It requires higher bias voltage (eight kilovolts), which lead to the development of a built-in power supply or water tight connector. Finally, a 50-cm micro-channel plate PMT (GDB-6203) was developed for water Cherenkov detectors by North Night Vision Technology Co., LTD in China. It is based on the GDB-6201 model, with improved timing performances. The charge resolutions for single photoelectron of the R12860, R12850 and GDB-6203 PMTs were evaluated to be 35%, 15%, and 40% (standard deviation), while the transit time spreads measured for single photoelectrons at a fixed threshold were 4.1, 3.6 and 4.3 nsec (FWHM) respectively. We obtained operational waterproof designs for all those photodetectors.

Access to Document (DOI)

Basic studies of 3-inch PMT for multi-PMT development

Inomoto M., Ishitsuka M., Kuze M., Nishimura Y., Quilain B.

Journal of Physics: Conference Series (Journal of Physics: Conference Series) 1468 ( 1 ) 2020.03

ISSN 17426588

Hyper-Kamiokande is the next generation large-scale water Cherenkov detector. In Hyper-Kamiokade and Intermediate Water Cherenkov Detector for its long baseline project with J-PARC neutrino beam, use of multi-PMT, which is made by combination of 3-inch PMTs, is being considered. As part of multi-PMT development, we measured the characteristics of the 3-inch PMT including the temperature dependence of dark noise rate. The dark noise rate is important characteristic for detection of low energy events including neutron tagging. In addition, since PMT is generally susceptible to the magnetic field, we confirmed the photon detection efficiency in the condition where the magnetic field was applied.

Access to Document (DOI)

Evaluation of position dependent performance of 3-inch PMTs for Multi-PMT development

Izumi N., Ishitsuka M., Kuze M., Nishimura Y., Quilain B.

Journal of Physics: Conference Series (Journal of Physics: Conference Series) 1468 ( 1 ) 2020.03

ISSN 17426588

Hyper-Kamiokande detector is proposed as a next generation underground water Cherenkov detector in Japan, and is planned to be an order of magnitude bigger than its predecessor, Super-Kamiokande. In order to further improve the detector capabilities in both low and high energy sectors, the multi-PMT modules instrumented with multiple 3-inch PMTs are being developed, in addition to the improved high quantum efficiency 20-inch PMTs. We developed a moveable laser system that can illuminate different positions on the photocathode to measure the characterization of the 3-inch PMTs as a function of the position on the photocathode.

Access to Document (DOI)

Development and performance of the 20" PMT for Hyper-Kamiokande

Bronner C., Nishimura Y., Xia J., Tashiro T.

Journal of Physics: Conference Series (Journal of Physics: Conference Series) 1468 ( 1 ) 2020.03

ISSN 17426588

The inner detector of the future Hyper-Kamiokande experiment will be instrumented with 40000 20" photo-multiplier tubes (PMTs). Two models of PMTs are considered: the R12860 from Hamamatsu Photonics (nominal option), and the GDB-6203 from North Night Vision Technology (alternative option). Both models show improved performances compared to the PMTs used in the currently running Super-Kamiokande experiment. We present here the measurements of the performance of the nominal and alternative option PMTs done in the context of the Hyper-Kamiokande project, as well as the first use of those new PMTs in a running experiment, and other on-going developments for their future use in the Hyper-Kamiokande detector.

Access to Document (DOI)

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

Tanaka M., Abe K., Bronner C., Hayato Y., Ikeda M., Imaizumi S., Ito H., Kameda J., Kataoka Y., Kato Y., Kishimoto Y., Marti L., 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-Bergunõ D., Labarga L., Fernandez P., Blaszczyk F.D.M., Kearns E., Raaf J.L., Stone J.L., Wan L., Wester T., Bian J., Griskevich N.J., Kropp W.R., Locke S., Mine S., Smy M.B., Sobel H.W., Takhistov V., Weatherly P., Hill J., Kim J.Y., Lim I.T., Park R.G., Bodur B., Scholberg K., Walter C.W., Coffani A., Drapier O., El Hedri S., Gonin M., Mueller T.A., Paganini P., Ishizuka T., Nakamura T., Jang J.S., Learned J.G., Matsuno S., Litchfield R.P., Sztuc A.A., Uchida Y., Berardi V., Catanesi M.G., Radicioni E., Calabria N.F., 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 A.T.

Physical Review D (Physical Review D) 101 ( 5 ) 2020.03

ISSN 24700010

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.

Access to Document (DOI)

Measurement of the muon neutrino charged-current single π+ production on hydrocarbon using the T2K off-axis near detector ND280

Abe K., Akutsu R., Ali A., Alt C., Amey J., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Atkin E.T., Awataguchi Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Beloshapkin A., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bordoni S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Calland R.G., Campbell T., Cao S., Cartwright S.L., Castillo R., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Cook L., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Eklund L., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda R., Fukuda Y., Gameil K., Garcia A., Giganti C., Gizzarelli F., Golan T., Gonin M., Gorin A., Guigue M., Hadley D.R., Haegel L., Haigh J.T., Hamacher-Baumann P., Hansen D., Harada J., Hartz M., Hasegawa T., Hastings N.C.

Physical Review D (Physical Review D) 101 ( 1 ) 2020.01

ISSN 24700010

We report the measurements of the single and double differential cross section of muon neutrino charged-current interactions on carbon with a single positively charged pion in the final state at the T2K off-axis near detector using 5.56×1020 protons on target. The analysis uses data control samples for the background subtraction and the cross section signal, defined as a single negatively charged muon and a single positively charged pion exiting from the target nucleus, is extracted using an unfolding method. The model-dependent cross section, integrated over the T2K off-axis neutrino beam spectrum peaking at 0.6 GeV, is measured to be σ=(11.76±0.44(stat)±2.39(syst))×10-40 cm2 nucleon-1. Various differential cross sections are measured, including the first measurement of the Adler angles for single charged pion production in neutrino interactions with heavy nuclei target.

Access to Document (DOI)

Measurement of neutrino and antineutrino neutral-current quasielasticlike interactions on oxygen by detecting nuclear deexcitation γ rays

Abe K., Akutsu R., Ali A., Alt C., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Atkin E.T., Awataguchi Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Beloshapkin A., Bench F., Berardi V., Berkman S., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bravo Bergunõ D., Bronner C., Bubak A., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Cook L., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Dumarchez J., Dunne P., Eklund L., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda R., Fukuda Y., Gameil K., Giganti C., Golan T., Gonin M., Gorin A., Guigue M., Hadley D.R., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hong Van N.T., Iacob F., Ichikawa A.K., Ikeda M., Ishida T.

Physical Review D (Physical Review D) 100 ( 11 ) 2019.12

ISSN 24700010

Access to Document (DOI)

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

Hagiwara K., Abe K., Bronner C., Hayato Y., Ikeda M., Ito H., Kameda J., Kataoka Y., Kato Y., Kishimoto Y., Marti L., 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 F.D.M., Kearns E., Raaf J.L., Stone J.L., Wan L., Wester T., Bian J., Griskevich N.J., Kropp W.R., Locke S., Mine S., Smy M.B., Sobel H.W., Takhistov V., Weatherly P., Ganezer K.S., Hill J., Kim J.Y., Lim I.T., Park R.G., Bodur B., Scholberg K., Walter C.W., Coffani A., Drapier O., Gonin M., Mueller T.A., Paganini P., Ishizuka T., Nakamura T., Jang J.S., Learned J.G., Matsuno S., Litchfield R.P., Sztuc A.A., Uchida Y., Berardi V., Calabria N.F., Catanesi M.G., 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 A.T., Takeuchi Y.

Astrophysical Journal Letters (Astrophysical Journal Letters) 887 ( 1 ) 2019.12

ISSN 20418205

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.

Access to Document (DOI)

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

Simpson C., Abe K., Bronner C., Hayato Y., Ikeda M., Ito H., Iyogi K., Kameda J., Kataoka Y., Kato Y., Kishimoto Y., Marti L., 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-Berguo D., Labarga L., Fernandez P., Blaszczyk F.D.M., Kachulis C., Kearns E., Raaf J.L., Stone J.L., Wan L., Wester T., Sussman S., Berkman S., Bian J., Griskevich N.J., Kropp W.R., Locke S., Mine S., Smy M.B., Sobel H.W., Takhistov V., Weatherly P., Ganezer K.S., Hill J., Kim J.Y., Lim I.T., Park R.G., Bodur B., Scholberg K., Walter C.W., Coffani A., Drapier O., Gonin M., Imber J., Mueller T.A., Paganini P., Ishizuka T., Nakamura T., Jang J.S., Choi K., Learned J.G., Matsuno S., Litchfield R.P., Sztuc A.A., Uchida Y., Wascko M.O., Berardi V., Calabria N.F., Catanesi M.G., Intonti R.A., Radicioni E., Rosa G.D., 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.

Astrophysical Journal (Astrophysical Journal) 885 ( 2 ) 2019.11

ISSN 0004637X

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.

Access to Document (DOI)

Measurement of the muon neutrino charged-current cross sections on water, hydrocarbon and iron, and their ratios, with the T2K on-axis detectors

Abe K., Akutsu R., Ali A., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Awataguchi Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda Y., Gameil K., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hong Van N.T., Hosomi F., Ichikawa A.K., Ikeda M., Inoue T., Intonti R.A., Ishida T., Ishii T., Ishitsuka M., Iwamoto K., Izmaylov A.

Progress of Theoretical and Experimental Physics (Progress of Theoretical and Experimental Physics) 2019 ( 9 ) 2019.09

We report a measurement of the flux-integrated νμ charged-current cross sections on water, hydrocarbon, and iron in the T2K on-axis neutrino beam with a mean neutrino energy of 1.5 GeV. The measured cross sections on water, hydrocarbon, and iron are σH2oCC = (0.840±0.010(stat.)+0.10-0.08(syst.)) ×10-38 cm2/nucleon, σCHCC = (0.817±0.007(stat.)+0.11-0.08(syst.)) × 10-38 cm2/nucleon, and σFeCC = (0.859±0.003(stat.)^+0.12-0.10(syst.)) ×10-38 cm2/nucleon, respectively, for a restricted phase space of induced muons: θμ < 45° and pμ > 0.4 GeV/c in the laboratory frame. The measured cross section ratios are σH2oCC/σCHCC = 1.028±0.016(stat.)±0.053(syst.), σFeCC/σH2oCC = 1.023±0.012(stat.)±0.058(syst.), and σFeCC/σCHCC = 1.049±0.010(stat.)±0.043(syst.). These results, with an unprecedented precision for the measurements of neutrino cross sections on water in the studied energy region, show good agreement with the current neutrino interaction models used in the T2K oscillation analyses.

Access to Document (DOI)

Search for heavy neutrinos with the T2K near detector ND280

Abe K., Akutsu R., Ali A., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Awataguchi Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., de Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda Y., Gameil K., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haegel L., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hong Van N.T., Hosomi F., Iacob F., Ichikawa A.K., Ikeda M., Inoue T., Intonti R.A., Ishida T., Ishii T., Ishitsuka M.

Physical Review D (Physical Review D) 100 ( 5 ) 2019.09

ISSN 24700010

This paper reports on the search for heavy neutrinos with masses in the range 140<MN<493 MeV/c2 using the off-axis near detector ND280 of the T2K experiment. These particles can be produced from kaon decays in the standard neutrino beam and then subsequently decay in ND280. The decay modes under consideration are N→ℓα±π and N→ℓα+ℓβ-ν(-)(α,β=e,μ). A search for such events has been made using the Time Projection Chambers of ND280, where the background has been reduced to less than two events in the current dataset in all channels. No excess has been observed in the signal region. A combined Bayesian statistical approach has been applied to extract upper limits on the mixing elements of heavy neutrinos to electron-, muon- and tau- flavored currents (Ue2, Uμ2, Uτ2) as a function of the heavy neutrino mass, e.g., Ue2<10-9 at 90% C.L. for a mass of 390 MeV/c2. These constraints are competitive with previous experiments.

Access to Document (DOI)

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

Jiang M., Abe K., Bronner C., Hayato Y., Ikeda M., Iyogi K., Kameda J., Kato Y., Kishimoto Y., Marti L., 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 F.D.M., Kachulis C., Kearns E., Raaf J.L., Stone J.L., Sussman S., Berkman S., Bian J., Griskevich N.J., Kropp W.R., Locke S., Mine S., Weatherly P., Smy M.B., Sobel H.W., Takhistov V., Ganezer K.S., Hill J., Kim J.Y., Lim I.T., Park R.G., Bodur B., Scholberg K., Walter C.W., Gonin M., Imber J., Mueller T.A., Ishizuka T., Nakamura T., Jang J.S., Choi K., Learned J.G., Matsuno S., Litchfield R.P., Uchida Y., Wascko M.O., Calabria N.F., Catanesi M.G., Intonti R.A., 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 K., Hasegawa M., Isobe Y., Miyabe H., Sugimoto T., Suzuki A.T., Takeuchi Y., Ashida Y.

Progress of Theoretical and Experimental Physics (Progress of Theoretical and Experimental Physics) 2019 ( 5 ) 2019.05

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.

Access to Document (DOI)

Search for light sterile neutrinos with the T2K far detector Super-Kamiokande at a baseline of 295 km

Abe K., Akutsu R., Ali A., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Awataguchi Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda Y., Gameil K., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hong Van N.T., Hosomi F., Iacob F., Ichikawa A.K., Ikeda M., Inoue T., Intonti R.A., Ishida T., Ishii T., Ishitsuka M., Iwamoto K.

Physical Review D (Physical Review D) 99 ( 7 ) 2019.04

ISSN 24700010

We perform a search for light sterile neutrinos using the data from the T2K far detector at a baseline of 295 km, with an exposure of 14.7(7.6)×1020 protons on target in neutrino (antineutrino) mode. A selection of neutral-current interaction samples is also used to enhance the sensitivity to sterile mixing. No evidence of sterile neutrino mixing in the 3+1 model was found from a simultaneous fit to the charged-current muon, electron and neutral-current neutrino samples. We set the most stringent limit on the sterile oscillation amplitude sin2θ24 for the sterile neutrino mass splitting Δm412<3×10-3 eV2/c4.

Access to Document (DOI)

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

Wan L., Abe K., Bronner C., Hayato Y., Ikeda M., Iyogi K., Kameda J., Kato Y., Kishimoto Y., Marti L., 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 F.D.M., Kachulis C., Kearns E., Raaf J.L., Stone J.L., Sussman S., Berkman S., Bian J., Griskevich N.J., Kropp W.R., Locke S., Mine S., Weatherly P., Smy M.B., Sobel H.W., Takhistov V., Ganezer K.S., Hill J., Kim J.Y., Lim I.T., Park R.G., Bodur B., Scholberg K., Walter C.W., Gonin M., Imber J., Mueller T.A., Ishizuka T., Nakamura T., Jang J.S., Choi K., Learned J.G., Matsuno S., Litchfield R.P., Uchida Y., Wascko M.O., Calabria N.F., Catanesi M.G., Intonti R.A., 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 K., Hasegawa M., Isobe Y., Miyabe H., Sugimoto T., Suzuki A.T., Takeuchi Y., Ashida Y.

Physical Review D (Physical Review D) 99 ( 3 ) 2019.02

ISSN 24700010

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.

Access to Document (DOI)

Search for neutral-current induced single photon production at the ND280 near detector in T2K

Abe K., Akutsu R., Ali A., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Awataguchi Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz-Kwasniak M., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., Rosa G.D., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda Y., Gameil K., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haigh J.T., Hamacher-Baumann P., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hong Van N.T., Hosomi F., Ichikawa A.K., Ikeda M., Inoue T., Intonti R.A., Ishida T., Ishii T., Ishitsuka M., Iwamoto K., Izmaylov A.

Journal of Physics G: Nuclear and Particle Physics (Journal of Physics G: Nuclear and Particle Physics) 46 ( 8 ) 2019

ISSN 09543899

Neutrino neutral-current (NC) induced single photon production is a subleading order process for accelerator-based neutrino beam experiments including T2K. It is, however, an important process to understand because it is a background for electron (anti)neutrino appearance oscillation experiments. Here, we performed the first search of this process below 1 GeV using the finegrained detector at the T2K ND280 off-axis near detector. By reconstructing single photon kinematics from electron positron pairs, we achieved 95% pure gamma ray sample from 5.738 1020 protons-on-targets neutrino mode data. We do not find positive evidence of NC induced single photon production in this sample. We set the model-dependent upper limit on the cross-section for this process, at 0.114 10-38 cm2 (90% C.L.) per nucleon, using the J-PARC off-axis neutrino beam with an average energy of .En. ~ 0.6 GeV. This is the first limit on this process below 1.GeV which is important for current and future oscillation experiments looking for electron neutrino appearance oscillation signals.

Access to Document (DOI)

Search for CP Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with 2.2×1021 Protons on Target

Abe K., Akutsu R., Ali A., Amey J., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz M., Bench F., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dokania N., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Fernandez P., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fujita R., Fukuda D., Fukuda Y., Gameil K., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haegel L., Haigh J.T., Hamacher-Baumann P., Hansen D., Harada J., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiramoto A., Hogan M., Holeczek J., Hosomi F., Ichikawa A.K., Ikeda M., Imber J., Inoue T., Intonti R.A., Ishida T., Ishii T.

Physical Review Letters (Physical Review Letters) 121 ( 17 ) 2018.10

ISSN 00319007

The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of 14.7(7.6)×1020 protons on target in the neutrino (antineutrino) mode, 89 νe candidates and seven anti-νe candidates are observed, while 67.5 and 9.0 are expected for δCP=0 and normal mass ordering. The obtained 2σ confidence interval for the CP-violating phase, δCP, does not include the CP-conserving cases (δCP=0, π). The best-fit values of other parameters are sin2θ23=0.526-0.036+0.032 and Δm322=2.463-0.070+0.071×10-3 eV2/c4.

Access to Document (DOI)

Measurement of the tau neutrino cross section in atmospheric neutrino oscillations with Super-Kamiokande

Li Z., Abe K., Bronner C., Hayato Y., Ikeda M., Iyogi K., Kameda J., Kato Y., Kishimoto Y., Marti L., Miura M., Moriyama S., Nakahata M., Nakajima Y., Nakano Y., Nakayama S., Orii A., Pronost G., Sekiya H., Shiozawa M., Sonoda Y., Takeda A., Takenaka A., Tanaka H., Tasaka S., Tomura T., Akutsu R., Kajita T., Nishimura Y., Okumura K., Tsui K.M., Fernandez P., Labarga L., Blaszczyk F.D.M., Gustafson J., Kachulis C., Kearns E., Raaf J.L., Stone J.L., Sulak L.R., Berkman S., Tobayama S., Elnimr M., Kropp W.R., Locke S., Mine S., Weatherly P., Smy M.B., Sobel H.W., Takhistov V., Ganezer K.S., Hill J., Kim J.Y., Lim I.T., Park R.G., Himmel A., O'Sullivan E., Scholberg K., Walter C.W., Ishizuka T., Nakamura T., Jang J.S., Choi K., Learned J.G., Matsuno S., Smith S.N., Amey J., Litchfield R.P., Ma W.Y., Uchida Y., Wascko M.O., Cao S., Friend M., Hasegawa T., Ishida T., Ishii T., Kobayashi T., Nakadaira T., Nakamura K., Oyama Y., Sakashita K., Sekiguchi T., Tsukamoto T., Abe K., Hasegawa M., Suzuki A.T., Takeuchi Y., Yano T., Hayashino T., Hiraki T., Hirota S., Huang K., Jiang M., Mori M., Nakamura K.E., Nakaya T., Patel N.D., Wendell R.A., Anthony L.H.V., McCauley N.

Physical Review D (Physical Review D) 98 ( 5 ) 2018.09

ISSN 24700010

Using 5326 days of atmospheric neutrino data, a search for atmospheric tau neutrino appearance has been performed in the Super-Kamiokande experiment. Super-Kamiokande measures the tau normalization to be 1.47±0.32 under the assumption of normal neutrino hierarchy, relative to the expectation of unity with neutrino oscillation. The result excludes the hypothesis of no-tau appearance with a significance level of 4.6σ. The inclusive charged-current tau neutrino cross section averaged by the tau neutrino flux at Super-Kamiokande is measured to be (0.94±0.20)×10-38 cm2. The measurement is consistent with the Standard Model prediction, agreeing to within 1.5σ.

Access to Document (DOI)

Characterization of nuclear effects in muon-neutrino scattering on hydrocarbon with a measurement of final-state kinematics and correlations in charged-current pionless interactions at T2K

Abe K., Amey J., Andreopoulos C., Anthony L., Antonova M., Aoki S., Ariga A., Ashida Y., Azuma Y., Ban S., Barbi M., Barker G.J., Barr G., Barry C., Batkiewicz M., Berardi V., Berkman S., Berner R.M., Berns L., Bhadra S., Bienstock S., Blondel A., Bolognesi S., Bordoni S., Bourguille B., Boyd S.B., Brailsford D., Bravar A., Bronner C., Buizza Avanzini M., Calcutt J., Campbell T., Cao S., Cartwright S.L., Catanesi M.G., Cervera A., Chappell A., Checchia C., Cherdack D., Chikuma N., Christodoulou G., Coleman J., Collazuol G., Coplowe D., Cudd A., Dabrowska A., De Rosa G., Dealtry T., Denner P.F., Dennis S.R., Densham C., Di Lodovico F., Dolan S., Drapier O., Duffy K.E., Dumarchez J., Dunne P., Emery-Schrenk S., Ereditato A., Feusels T., Finch A.J., Fiorentini G.A., Fiorillo G., Francois C., Friend M., Fujii Y., Fukuda D., Fukuda Y., Garcia A., Giganti C., Gizzarelli F., Golan T., Gonin M., Hadley D.R., Haegel L., Haigh J.T., Hamacher-Baumann P., Hansen D., Harada J., Hartz M., Hasegawa T., Hastings N.C., Hayashino T., Hayato Y., Hiraki T., Hiramoto A., Hirota S., Hogan M., Holeczek J., Hosomi F., Ichikawa A.K., Ikeda M., Imber J., Inoue T., Intonti R.A., Ishida T., Ishii T., Iwamoto K., Izmaylov A., Jamieson B.

Physical Review D (Physical Review D) 98 ( 3 ) 2018.08

ISSN 24700010

This paper reports measurements of final-state proton multiplicity, muon and proton kinematics, and their correlations in charged-current pionless neutrino interactions, measured by the T2K ND280 near detector in its plastic scintillator (C8H8) target. The data were taken between years 2010 and 2013, corresponding to approximately 6×1020 protons on target. Thanks to their exploration of the proton kinematics and of imbalances between the proton and muon kinematics, the results offer a novel probe of the nuclear-medium effects most pertinent to the (sub-)GeV neutrino-nucleus interactions that are used in accelerator-based long-baseline neutrino oscillation measurements. These results are compared to many neutrino-nucleus interaction models which all fail to describe at least part of the observed phase space. In case of events without a proton above a detection threshold in the final state, a fully consistent implementation of the local Fermi gas model with multinucleon interactions gives the best description of the data. In the case of at least one proton in the final state, the spectral function model agrees well with the data, most notably when measuring the kinematic imbalance between the muon and the proton in the plane transverse to the incoming neutrino. Within the models considered, only the existence of multinucleon interactions are able to describe the extracted cross section within regions of high transverse kinematic imbalance. The effect of final-state interactions is also discussed.

Access to Document (DOI)

　 Previous page - Next page 　