Development of a novel small-sized neutron detector based on a 6Li-glass scintillator

A small-sized thermal neutron detector based on a ⁶Li-glass scintillator and a plastic optical fiber was developed for measurement of a dose distribution of thermal neutrons in a thermal-neutron standard field. A contribution of gamma rays can not completely be neglected in the neutron measurement with this detector, although the ⁶Li-glass scintillator is distinguishable for the neutrons and the gamma rays by difference of each pulse height. Moreover, to reduce an uncertainty of neutron counts caused by the gamma ray background around a discrimination level, we suggested a gamma-ray suppression type of a small-sized thermal neutron detector with a ⁶Li-glass scintillator, a hollow CsI(Tl) scintillator and plastic optical fibers. The detector can reject signals due to the gamma rays with an anti-coincidence method. In the present paper, we evaluated the gamma-ray suppression ability of the detector using the EGS4 electron-photon transport Monte-Carlo code with the PRESTA routine. As the results, the sufficient gamma-ray suppression effect was shown.