  The JSNS2 (J-PARC E56) experiment aims to search for sterile neutrinos at the
J-PARC Materials and Life Sciences Experimental Facility (MLF).After the
submission of a proposal to the J-PARC PAC, stage-1 approval was granted to the
JSNS2 experiment. The approval followed a series of background measurements
which were performed in 2014. Subsequent for stage-1 approval, the JSNS2
collaboration has made continuous efforts to write a Technical Design Report
(TDR).This TDR will include two major items as discussed in the previous status
report for the 20th J-PARC PAC: (1) A realistic detector location (2) Well
understood and realistic detector performance using simulation studies,
primarily in consideration of fast neutron rejection. Since August we have been
in discussions with MLF staff regarding an appropriate detector location. We
are also in the process of setting up a Monte Carlo (MC) simulation framework
in order to study detector's performance in realistic conditions. In addition,
we have pursued hardware R&D work for the liquid scintillator (LS) and to
improve the dynamic range of the 10" photomultiplier tubes (PMTs). The LS R&D
works includes Cherenkov studies inside the LS, and a Pulse Shape
Discrimination (PSD) study with a test-beam, performed at Tohoku University. We
also estimate the PSD performance of a full-sized detector using a detailed MC
simulation. In this status report, we describe progress on this work.
