Detector upgrade for SENJU neutron diffractometer at J-PARC MLF

Nakamura, Tatsuya  ; To, Kentaro  ; Kiyanagi, Ryoji  ; Ohara, Takashi   ; Hosoya, Takaaki; Tobe, Masahiro; Hishinuma, Yukio*; Ebine, Masumi ; Sakasai, Kaoru  

New detector modules have been developed based on a Li:ZnS scintillator and wavelength-shifting fibers technology to upgrade the detectors for SENJU neuron diffractometer at J-PARC MLF. The detector upgrade plan includes (1) Thin-type add-in detectors, (2) High efficiency detectors to replace the original ones, (3) a large area detector for installation under the sample vacuum tank (Large area bottom detector), and (4) One detector-bank detectors. As for (1) and (2) the detector modules have been developed with a 1.5-fold improved detection efficiency with a 50-60% smaller detector depth. 4 add-in detectors and 6 replacement detectors have been manufactured and installed to the diffractometer. The large area bottom detector that has a four-fold larger neutron-sensitive area than the original detector, has also been developed. To increase the light collection efficiency a scintillation light is collected from the both ends of the wavelength-shifting fiber. The prototype detector exhibited an acceptable count uniformity 59% over the detector.