Supernova Relic Neutrino Search with Neutron Tagging at Super-Kamiokande-IV

Abstract

A search for Supernova Relic Neutrinos ${\bar{\nu }}_e$'s is first conducted via inverse-beta-decay by tagging neutron capture on hydrogen at Super-Kamiokande-IV. The neutron tagging efficiency is determined to be $(17.74\pm 0.04_{stat.}\pm 1.05_{sys.})$, while the corresponding accidental background probability is $(1.06\pm 0.01_{stat.}\pm 0.18_{sys.})$%. Using 960 days of data, we obtain 13 inverse-beta-decay candidates in the range of $E_{{\bar{\nu }}_e}$ between 13.3 MeV and 31.3 MeV. All of the observed candidates are attributed to background. Upper limits at 90% C.L. are calculated in the absence of a signal.

6 pages, 4 figures