Evaluation of Detector Performances of New Thin Position-Sensitive Scintillation Detectors for SENJU Diffractometer

A new thin position-sensitive scintillation neutron detectors have been developed to replace present scintillation detectors in SENJU diffractometer at J-PARC MLF. The SENJU diffractometer originally composed of 37 position-sensitive detectors, where each detector has neutron sensitive area of 256 × 256 mm with a pixel size of 4 × 4 mm. To renew some original detectors the new detectors have been developed based on
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Li:ZnS scintillator and wavelength-shifting fibers technology. The developed replacement detectors were designed with a thin thickness of 12 cm, which is 40% of the original detector. The new detectors have also improved detector performances to the original ones in terms of detection efficiency (~60% for 2-Å neutrons) and count uniformity (5~8%). The produced six detector modules have been implemented to the beamline after checking their detector performances with a
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Cf source. All the detectors have been operated in stable for a couple of months in the beamline. The background count rates were measured 200~350 1/hr/detector, which are consistent with the data measured in the laboratory.