Eur. Phys. J. C (2024) 84: 409
https://doi.org/10.1140/epjc/s10052-024-12778-7

Regular Article - Experimental Physics

Study on the accidental background of the JSNS${}^2$ experiment

¹ High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan
² Research Center for Nuclear Physics, Osaka University, Osaka, Japan
³ Department of Physics, Soongsil University, 06978, Seoul, Korea
⁴ Laboratory for High Energy Physics, Dongshin University, 58245, Chonnam, Korea
⁵ Department of Fire Safety, Seoyeong University, 61268, Gwangju, Korea
⁶ Research Center for Neutrino Science, Tohoku University, Sendai, Miyagi, Japan
⁷ Department of Physics, Kyung Hee University, 02447, Seoul, Korea
⁸ J-PARC Center, JAEA, Tokai, Ibaraki, Japan
⁹ Advanced Science Research Center, JAEA, Ibaraki, Japan
¹⁰ Gwangju Institute of Science and Technology, 61005, Gwangju, Korea
¹¹ Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
¹² Department of Physics, Chonnam National University, 61186, Gwangju, Korea
¹³ School of Liberal Arts, Seoul National University of Science and Technology, 139-743, Seoul, Korea
¹⁴ Department of Physics, Kitasato University, 252-0373, Sagamihara, Kanagawa, Japan
¹⁵ Division of Science Education, Jeonbuk National University, 54896, Jeonju, Korea
¹⁶ School of Physics, Sun Yat-sen (Zhongshan) University, 510275, Guangzhou, China
¹⁷ Department of Physics, Kyungpook National University, 41566, Daegu, Korea
¹⁸ University of Michigan, 48109, Ann Arbor, MI, USA
¹⁹ Department of Physics, Kyoto Sangyo University, Kyoto, Japan
²⁰ Department of Physics and Astronomy, University of Sussex, Brighton, UK
²¹ Department of Physics and Astronomy, The University of Utah, 84112, Salt Lake City, UT, USA
²² Brookhaven National Laboratory, 11973-5000, Upton, NY, USA

^a leedh@post.kek.jp
^au jungsicpark@knu.ac.kr

Received: 4 August 2023
Accepted: 8 April 2024
Published online: 22 April 2024

Abstract

JSNS${}^2$ (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that searches for sterile neutrinos via the observation of ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_e$ appearance oscillations using muon decay-at-rest neutrinos. The JSNS${}^2$ experiment performed data taking from 2021. In this manuscript, a study of the accidental background is presented. The rate of the accidental background is ($9.29\pm 0.39)\times {10}^{-8}$/spill with 0.75 MW beam power and comparable to the expected number of signal events.