Detector system of the single-crystal time-of-flight neutron diffractometer at J-PARC/MLF

Kawasaki, Takuro   ; Nakamura, Tatsuya  ; To, Kentaro  ; Hosoya, Takaaki*; Oikawa, Kenichi   ; Ohara, Takashi   ; Kiyanagi, Ryoji  ; Ebine, Masumi ; Birumachi, Atsushi; Sakasai, Kaoru  ; Soyama, Kazuhiko  ; Katagiri, Masaki*

The detector system of - a single-crystal time-of-flight neutron diffractometer - is described. is the first diffractometer employing a large-area two-dimensional wavelength shifting fibre-based scintillator detector at the Material and Life Science Experimental Facility at the Japan Proton Accelerator Research Complex. Thirty-seven detectors were installed in the instrument to cover a scattering angle of 30%. The detector modules exhibited a detector efficiency of 37-471% for thermal neutrons, a Co -ray sensitivity of 1.4-5.10.110, a background count rate of 2.1-3.81.010 cps/cm and a tolerance to stray magnetic fields up to 120 gauss. The detector exhibited stable performance under the operating conditions used, such as stable count rates over 400 days and a count temperature coefficient of -0.010.02%/C at around 20C.