Speaker
Mr
Huang Kunxian for T2K collaboration Huang
(Kyoto University)
Description
We report the first measurement of the neutral current quasi-elastic (NCQE) cross section on oxygen by observing nuclear de-excitation gamma rays with the T2K neutrino beam. These interactions from atmospheric neutrinos are one of the main backgrounds in supernova relic neutrino searches. These gamma rays are observed in the Super-Kamiokande (SuperK) water Cherenkov detector. We select candidate events by using the T2K beam timing, dramatically reducing the background of natural radioactivity. We observed 43 events in the 4-30 MeV reconstructed energy region, compared with the MC prediction 55.7 with an estimated NCQE signal efficiency of about 70%. We observed an NCQE cross section of 1.35X10^-38(cm^2) with a 68% confidence interval of (1.06, 1.94)X10^-38(cm^2).
Primary author
Mr
Huang Kunxian for T2K collaboration Huang
(Kyoto University)