Detector performances of large area scintillator / wavelength shifting fiber neutron detectors for SENJU upgrade at J-PARC MLF

Nakamura, Tatsuya  ; To, Kentaro  ; Kiyanagi, Ryoji  ; Ohara, Takashi   ; Hosoya, Takaaki; Sakasai, Kaoru  

Detector performances of large area two-dimensional neutron detectors produced for upgrade of SENJU diffractometer at Materials and Life science experimental Facility at J-PARC have been evaluated. The detectors are developed based on a Li:ZnS(Ag) scintillator and wavelength-shifting fiber technology. The prototype detector has a neutron-sensitive area of 512 768 mm, which is six-fold of the original detector installed in the SENJU. The prototype detector exhibited a detection efficiency of 40-50% for 2- space neutrons and Co gamma-ray sensitivity of ~10. 9 detector modules have been produced for the planned SENJU upgrade. The produced detectors exhibited similar detector efficiencies and gamma-ray sensitivities to that of the prototype detector. Neutron counts of these detectors with a Cf source varied within 5% to the average. The experimental results of the prototype and the produced beamline detectors are presented.