Development of neutron detector using the PIN photodiode with polyethylene (n,p) converter

A Si photodiode detector PIN-type 10/spl times/10 mm, with a slim film of a converter material capable of producing charged particles, was used as sensor of neutrons and it was projected to be used in an environment of a zero power reactor. Polyethylene n(CH/sub 2/), which produces recoil protons from the (n,p) interaction, was used to improve the detection efficiency. A mathematical model was applied to fit the experimental data and the optimal thickness of the converters was determined by the maximum point of the function. For an AmBe source, the optimum polyethylene layer thickness was of 0.105 cm (96.6 mg/spl middot/cm/sup -2/). The converter of polyethylene was capable to improve the detection efficiency to a factor of 16.4 compared to measurement without converter. The detector shows a good response (r=0.999372) to estimate the power variation during the operation of the zero power-type reactor (IPEN/MB-01).