Diagnosis Of Neutron Sensitivity Within A Scintillator/Wavelength-Shifting Fiber Coil Element By Using A Collimated Pulsed Neutron Beam

We have developed a position-sensitive tubular scintillation neutron detector as an alternative to a He-3 gas based detector. The detector comprises a number of individual neutron-sensitive elements, where a pair of wound wavelength-shifting fiber coils is sandwiched with two rolled ZnS/(LiF)-Li-6 scintillator screens in each element. Position-dependent neutron sensitivity within the scintillator / wavelength-shifting fiber coil (SFC) element was evaluated by using a collimated pulsed neutron beam at the J-PARC MLF. The collimated beam that has a size of 1 x 1 mm(2) scanned over the SFC element. Neutron counts were recorded and plotted as a function of incident beam position. The scanning results showed less neutron sensitivity at the juncture of the rolled scintillator screens, which indicated a lack of scintillator materials due to imperfect manufacturing process.