Measurement of delayed neutrons from J-PARC spallation neutron source

Harada, Masahide   ; Teshigawara, Makoto   ; Oi, Motoki ; Yamaguchi, Yuji   ; Oikawa, Kenichi   ; Tsuchikawa, Yusuke ; Haga, Katsuhiro  

At J-PARC 1MW spallation neutron source, pulsed neutrons included by 25Hz pulsed proton beam are provided to neutron instruments. Recently, 800 kW proton beam operation is successful, and the proton beam power gradually increases. A neutron instrument observed neutron beams with weak time correction to proton pulse. Therefore, at the neutron instrument to measure neutron pulse characteristics, NOBORU, we tried to measure delayed neutrons. In the measurement, a neutron detector was located on the beam axis in the NOBORU experimental room and pulsed neutrons were measured with flight time after the beam operation stop. Pulse height was also measured to distinguish whether neutron or others. From the results, neutrons could be measured after the beam operation stop. We will present in details in the conference.