Multiwire-type two-dimensional neutron detector with high pressure for J-PARC MLF BL17 neutron reflectometer

藤 健太郎  ; 中村 龍也  ; 坂佐井 馨  ; 山岸 秀志*

To, Kentaro; Nakamura, Tatsuya; Sakasai, Kaoru; Yamagishi, Hideshi*

Neutron reflectometry experiments using a gaseous two-dimensional neutron detector system with multiwire elements have been performed at the MLF BL17 Sharaku at the J-PARC Center. We have developed a two-dimensional neutron detector for BL17 utilizing a multiwire-type detector element known for its reliability. This system has been operating reliably for over 10 years without major maintenance. Initially, the detector used a low-pressure fill gas (0.27 MPa) due to a helium-3 shortage. To improve sensitivity, a new high-pressure detector (0.7 MPa) was developed, featuring a robust pressure vessel and updated signal processing circuits. Pulsed neutron irradiation tests showed that the new detector's sensitivity at the TOF peak (12.4 ms, neutron energy 11 meV) was approximately twice that of the original detector. Results from a Cf source and pulsed neutrons will be presented.