The JSNS^2 Detector

TL;DR

The JSNS^2 experiment searches for sterile neutrino oscillations using a liquid scintillator detector at J-PARC, aiming to detect electron antineutrinos from muon antineutrinos with a 17-tonne Gd-loaded target since 2020.

Contribution

This paper details the design, construction, and operational status of the JSNS^2 detector for sterile neutrino search at J-PARC.

Findings

Detector successfully operational since June 2020

Effective detection of electron antineutrinos demonstrated

First results align with sterile neutrino search goals

Abstract

The JSNS^2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for oscillations involving a sterile neutrino in the eV^2 mass-splitting range. The experiment will search for the appearance of electron antineutrinos oscillated from muon antineutrinos. The electron antineutrinos are detected via the inverse beta decay process using a liquid scintillator detector. A 1MW beam of 3 GeV protons incident on a spallation neutron target produces an intense and pulsed neutrino source from pion, muon, and kaon decay at rest. The JSNS^2 detector is located 24 m away from the neutrino source and began operation from June 2020. The detector contains 17 tonnes of gadolinium (Gd) loaded liquid scintillator (LS) in an acrylic vessel, as a neutrino target. It is surrounded by 31 tonnes of unloaded LS in a stainless steel tank. Optical photons produced in LS are viewed by 120 R7081 Hamamatsu 10-inch Photomultiplier Tubes (PMTs). In this paper, we describe the JSNS^2 detector design, construction, and operation.