Performance of PMTs for the JSNS² experiment

Abstract

The JSNS2 (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment aims to search for neutrino oscillations over a 24 m short baseline at J-PARC . The JSNS2 inner detector is filled with 17 tons of gadolinium-loaded liquid scintillator (LS) and both the intermediate γ-catcher and the optically separated outer veto are filled with un-loaded LS . Optical photons from scintillation are observed by 120 Photomultiplier Tubes (PMTs). A total of 130 PMTs for the JSNS2 experiment were either donated by other experiments or purchased from Hamamatsu. Donated PMTs were purchased around 10 years ago, therefore JSNS2 did pre-calibration of the PMTs including the purchased PMTs. 123 PMTs demonstrated acceptable performance for the JSNS2 experiment, and 120 PMTs were installed in the detector.

The JSNS2 data acquisition system

“…The optically separated γ-catcher and outer veto are filled with 31 tons of unloaded LS. A total of 120 10-inch photomultiplier tubes (PMTs) were precalibrated [4] and installed in the detector. Of the 120 PMTs, 96 are directed inward to view the target volume and 24 PMTs view the veto.…”