TY - JOUR
T1 - Search for Astrophysical Electron Antineutrinos in Super-Kamiokande with 0.01% Gadolinium-loaded Water
AU - The Super-Kamiokande Collaboration
AU - Harada, M.
AU - Abe, K.
AU - Bronner, C.
AU - Hayato, Y.
AU - Hiraide, K.
AU - Hosokawa, K.
AU - Ieki, K.
AU - Ikeda, M.
AU - Kameda, J.
AU - Kanemura, Y.
AU - Kaneshima, R.
AU - Kashiwagi, Y.
AU - Kataoka, Y.
AU - Miki, S.
AU - Mine, S.
AU - Miura, M.
AU - Moriyama, S.
AU - Nakano, Y.
AU - Nakahata, M.
AU - Nakayama, S.
AU - Noguchi, Y.
AU - Okamoto, K.
AU - Sato, K.
AU - Sekiya, H.
AU - Shiba, H.
AU - Shimizu, K.
AU - Shiozawa, M.
AU - Sonoda, Y.
AU - Suzuki, Y.
AU - Takeda, A.
AU - Takemoto, Y.
AU - Takenaka, A.
AU - Tanaka, H.
AU - Watanabe, S.
AU - Yano, T.
AU - Han, S.
AU - Kajita, T.
AU - Okumura, K.
AU - Tashiro, T.
AU - Tomiya, T.
AU - Wang, X.
AU - Yoshida, S.
AU - Bhuiyan, N.
AU - Burton, G. T.
AU - Di Lodovico, F.
AU - Goldsack, A.
AU - Katori, T.
AU - Migenda, J.
AU - Xie, Z.
AU - Zsoldos, S.
N1 - Funding Information:
We gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. The Super-Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the National Research Foundation of Korea (NRF-2009-0083526 and NRF 2022R1A5A1030700) funded by the Ministry of Science, ICT, the Institute for Basic Science (IBS-R016-Y2), and the Ministry of Education (2018R1D1A1B07049158, 2021R1I1A1A01042256, the Japan Society for the Promotion of Science, the National Natural Science Foundation of China under grants No. 11620101004, the Spanish Ministry of Science, Universities and Innovation (grant PID2021-124050NB-C31), the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Scinet and Westgrid consortia of Compute Canada, the National Science Centre (UMO-2018/30/E/ST2/00441) and the Ministry of Education and Science (DIR/WK/2017/05), Poland, the Science and Technology Facilities Council (STFC) and GridPP, UK, the European Union's Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement No. 754496, H2020-MSCA-RISE-2018 JENNIFER2 grant agreement No. 822070, and H2020-MSCARISE- 2019 SK2HK grant agreement No. 872549.
Funding Information:
We gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. The Super-Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the National Research Foundation of Korea (NRF-2009-0083526 and NRF 2022R1A5A1030700) funded by the Ministry of Science, ICT, the Institute for Basic Science (IBS-R016-Y2), and the Ministry of Education (2018R1D1A1B07049158, 2021R1I1A1A01042256, the Japan Society for the Promotion of Science, the National Natural Science Foundation of China under grants No. 11620101004, the Spanish Ministry of Science, Universities and Innovation (grant PID2021-124050NB-C31), the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Scinet and Westgrid consortia of Compute Canada, the National Science Centre (UMO-2018/30/E/ST2/00441) and the Ministry of Education and Science (DIR/WK/2017/05), Poland, the Science and Technology Facilities Council (STFC) and GridPP, UK, the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement No. 754496, H2020-MSCA-RISE-2018 JENNIFER2 grant agreement No. 822070, and H2020-MSCA-RISE-2019 SK2HK grant agreement No. 872549.
Publisher Copyright:
© 2023. The Author(s).
PY - 2023/7/7
Y1 - 2023/7/7
N2 - We report the first search result for the flux of astrophysical electron antineutrinos for energies(10)MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In 2020 June, gadolinium was introduced to the ultrapure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd, during 2020 August 26, and 2022 June 1 with a 22.5 × 552 kton · day exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure water (22.5 × 2970 kton · day) owing to the enhanced neutron tagging. Operation with Gd increased to 0.03% started in 2022 June.
AB - We report the first search result for the flux of astrophysical electron antineutrinos for energies(10)MeV in the gadolinium-loaded Super-Kamiokande (SK) detector. In 2020 June, gadolinium was introduced to the ultrapure water of the SK detector in order to detect neutrons more efficiently. In this new experimental phase, SK-Gd, we can search for electron antineutrinos via inverse beta decay with efficient background rejection thanks to the high efficiency of the neutron tagging technique. In this paper, we report the result for the initial stage of SK-Gd, during 2020 August 26, and 2022 June 1 with a 22.5 × 552 kton · day exposure at 0.01% Gd mass concentration. No significant excess over the expected background in the observed events is found for the neutrino energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90% confidence level. The limits and sensitivities are already comparable with the previous SK result with pure water (22.5 × 2970 kton · day) owing to the enhanced neutron tagging. Operation with Gd increased to 0.03% started in 2022 June.
UR - http://www.scopus.com/inward/record.url?scp=85166270564&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/acdc9e
DO - 10.3847/2041-8213/acdc9e
M3 - Article
AN - SCOPUS:85166270564
SN - 2041-8205
VL - 951
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L27
ER -