Study on the accidental background of the JSNS² experiment

JSNS ² 2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) is an experiment that searches for sterile neutrinos via the observation of ν ̄μ → ν ̄ₑ ν ¯ μ → ν ¯ e appearance oscillations using muon decay-at-rest neutrinos. The JSNS ² 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± 0.39) × 10⁻⁸ 9.29 ± 0.39 ) × 10 - 8 /spill with 0.75 MW beam power and comparable to the expected number of signal events.