Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1510.08127

Measurements of the atmospheric neutrino flux by Super-Kamiokande: energy spectra, geomagnetic effects, and solar modulation

E. Richard·K. Okumura·K. Abe·Y. Haga·Y. Hayato·M. Ikeda·K. Iyogi·J. Kameda·Y. Kishimoto·M. Miura·S. Moriyama·M. Nakahata·T. Nakajima·Y. Nakano·S. Nakayama·A. Orii·H. Sekiya·M. Shiozawa·A. Takeda·H. Tanaka·T. Tomura·R. A. Wendell·R. Akutsu·T. Irvine·T. Kajita·K. Kaneyuki·Y. Nishimura·L. Labarga·P. Fernandez·J. Gustafson·C. Kachulis·E. Kearns·J. L. Raaf·J. L. Stone·L. R. Sulak·S. Berkman·C. M. Nantais·H. A. Tanaka·S. Tobayama·M. Goldhaber·W. R. Kropp·S. Mine·P. Weatherly·M. B. Smy·H. W. Sobel·V. Takhistov·K. S. Ganezer·B. L. Hartfiel·J. Hill·N. Hong·J. Y. Kim·I. T. Lim·R. G. Park·A. Himmel·Z. Li·E. OSullivan·K. Scholberg·C. W. Walter·T. Wongjirad·T. Ishizuka·S. Tasaka·J. S. Jang·J. G. Learned·S. Matsuno·S. N. Smith·M. Friend·T. Hasegawa·T. Ishida·T. Ishii·T. Kobayashi·T. Nakadaira·K. Nakamura·Y. Oyama·K. Sakashita·T. Sekiguchi·T. Tsukamoto·A. T. Suzuki·Y. Takeuchi·T. Yano·S. V. Cao·T. Hiraki·S. Hirota·K. Huang·T. Kikawa·A. Minamino·T. Nakaya·K. Suzuki·Y. Fukuda·K. Choi·Y. Itow·T. Suzuki·P. Mijakowski·K. Frankiewicz·J. Hignight·J. Imber·C. K. Jung·X. Li·J. L. Palomino·M. J. Wilking·C. Yanagisawa
View original source ↗Read source document ↗Export metadata ↓

Abstract

A comprehensive study on the atmospheric neutrino flux in the energy region from sub-GeV up to several TeV using the Super-Kamiokande water Cherenkov detector is presented in this paper. The energy and azimuthal spectra of the atmospheric $ν_e+{\barν}_e$ and $ν_μ+{\barν}_μ$ fluxes are measured. The energy spectra are obtained using an iterative unfolding method by combining various event topologies with differing energy responses. The azimuthal spectra depending on energy and zenith angle, and their modulation by geomagnetic effects, are also studied. A predicted east-west asymmetry is observed in both the $ν_e$ and $ν_μ$ samples at 8.0 σ and 6.0 σ significance, respectively, and an indication that the asymmetry dipole angle changes depending on the zenith angle was seen at the 2.2 σ level. The measured energy and azimuthal spectra are consistent with the current flux models within the estimated systematic uncertainties. A study of the long-term correlation between the atmospheric neutrino flux and the solar magnetic activity cycle is also performed, and a weak indication of a correlation was seen at the 1.1 σ level, using SK I-IV data spanning a 20 year period. For particularly strong solar activity periods known as Forbush decreases, no theoretical prediction is available, but a deviation below the typical neutrino event rate is seen at the 2.4 σ level.

Explore related subjects

hep-exastro-ph.HEastro-ph.SRphysics.ins-det

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

E. Richard, K. Okumura, K. Abe, Y. Haga, Y. Hayato, M. Ikeda, K. Iyogi, J. Kameda, Y. Kishimoto, M. Miura, S. Moriyama, M. Nakahata, T. Nakajima, Y. Nakano, S. Nakayama, A. Orii, H. Sekiya, M. Shiozawa, A. Takeda, H. Tanaka, T. Tomura, R. A. Wendell, R. Akutsu, T. Irvine, T. Kajita, K. Kaneyuki, Y. Nishimura, L. Labarga, P. Fernandez, J. Gustafson, C. Kachulis, E. Kearns, J. L. Raaf, J. L. Stone, L. R. Sulak, S. Berkman, C. M. Nantais, H. A. Tanaka, S. Tobayama, M. Goldhaber, W. R. Kropp, S. Mine, P. Weatherly, M. B. Smy, H. W. Sobel, V. Takhistov, K. S. Ganezer, B. L. Hartfiel, J. Hill, N. Hong, J. Y. Kim, I. T. Lim, R. G. Park, A. Himmel, Z. Li, E. OSullivan, K. Scholberg, C. W. Walter, T. Wongjirad, T. Ishizuka, S. Tasaka, J. S. Jang, J. G. Learned, S. Matsuno, S. N. Smith, M. Friend, T. Hasegawa, T. Ishida, T. Ishii, T. Kobayashi, T. Nakadaira, K. Nakamura, Y. Oyama, K. Sakashita, T. Sekiguchi, T. Tsukamoto, A. T. Suzuki, Y. Takeuchi, T. Yano, S. V. Cao, T. Hiraki, S. Hirota, K. Huang, T. Kikawa, A. Minamino, T. Nakaya, K. Suzuki, Y. Fukuda, K. Choi, Y. Itow, T. Suzuki, P. Mijakowski, K. Frankiewicz, J. Hignight, J. Imber, C. K. Jung, X. Li, J. L. Palomino, M. J. Wilking, C. Yanagisawa. 2016-09-06. Measurements of the atmospheric neutrino flux by Super-Kamiokande: energy spectra, geomagnetic effects, and solar modulation. https://doi.org/10.1103/physrevd.94.052001

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Charge-dependent atmospheric muon flux at 17 GV geomagnetic cutoff with the mini-ICAL detector

The Iron CALorimeter (ICAL) detector at the India-Based Neutrino Observatory (INO) was conceived as an underground experiment designed to measure atmospheric neutrino oscillation parameters. As part of the R\&D programme, a scaled prototype (mini-ICAL), 85\,ton, approximately 1/600$^{\mathrm{th}}$ the mass of the full detector, was constructed at the IICHEP Transit Campus, Madurai (altitude 150\,m; latitude 9.9372$^\circ$\,N; longitude 78.013$^\circ$\,E; geomagnetic latitude 1.44$^\circ$\,N; vertical cutoff rigidity 17\,GV) and operated between 2018 and 2022. The prototype enabled measurements of charge-dependent cosmic muon spectra in the vicinity of the geomagnetic equator and provided an important validation of detector performance, reconstruction algorithms, and simulation frameworks for the ICAL experiment. Differential fluxes of $μ^{-}$ and $μ^{+}$ were measured over the momentum range $\sim$\,1--5\,GeV/c. The obtained momentum spectra are systematically lower than those reported at sites with smaller geomagnetic cutoff rigidities, consistent with the suppression of low- and intermediate-rigidity primary cosmic rays at the 17\,GV cutoff. The measurements are compared with predictions from different hadronic interaction models available in CORSIKA simulations.

hep-ex↗
arXiv2026

Laboratory constraints on peV-scale mass splitting between ordinary and sterile neutron states

Sterile states of matter, represented by a parallel ``mirror'' sector, may contribute to the observed dark matter in the Universe. We investigated the parameter space of neutron $(n)$ to mirror-neutron $(n')$ oscillations, in the case where the two states are not necessarily mass-degenerate, taking into account interactions in the mirror sector. By tuning the magnitude of an applied magnetic-field in the range $5~μ\mathrm{T} < B < 360~μ\mathrm{T}$ to corresponding resonance conditions for finite mass splitting, we derive exclusion limits for the $n-n'$ oscillation time constant reaching about $20~\text{s}$ over the mass-difference range $0.3 - 22~\text{peV}$. In parts of this parameter range, our limits exceed the model-dependent neutron-star-cooling bound, providing the first experimental constraints in this scenario that are more stringent than this astrophysical estimate.

hep-ex↗
arXiv2026

Search for the $^{16}\text{O}(ppp) \rightarrow ^{13}\text{C} π^+ π^+ e^+$ Decay Mode in Super-Kamiokande Using Machine Learning Techniques

We report a new partial lifetime limit of $4.2 \times 10^{32}$ years for the trinucleon decay mode $^{16}\text{O}(ppp) \rightarrow ^{13}\text{C} π^+ π^+ e^+$, obtained from a search conducted using the Super-Kamiokande detector with 0.401 megaton-years of exposure across five operational periods (SK-I: 1996--2001, SK-II: 2002--2005, SK-III: 2006--2008, SK-IV: 2008--2018, SK-V: 2019--2020). This represents an improvement of six orders of magnitude over previous experimental constraints. The analysis utilizes a convolutional neural network (CNN) incorporating an attention mechanism---a computational technique that enables the model to focus on the most relevant regions of Cherenkov ring patterns---to enhance event classification, thereby improving the sensitivity of the search. This is the first application of a CNN to a nucleon decay search in Super-Kamiokande. Furthermore, the large dataset available in Super-Kamiokande (hereafter "SK") strengthens the statistical power of the study, enabling a more stringent constraint than those set by prior experiments.

hep-ex↗