Development of a Compact Flat Response Neutron Detector

作者：Harano H^*; Matsumoto T; Nishiyama J; Masuda A; Uritani A; Kudo K

来源：IEEE Transactions on Nuclear Science, 2011, 58(5): 2421-2425.

DOI：10.1109/TNS.2011.2163191

• Effective center
• flat response
• long counter
• neutron energy evaluation
• neutron fluence measurement

Long counters are widely used as neutron fluence monitors for their flat response. However, a bulky neutron moderator is required to achieve the flat response, which can be a disadvantage for portability and an undesirable source of scattered neutrons. Reducing the size of the moderator degrades the flat response, especially for high-energy neutrons. We propose a new method to reduce the size of the moderator while keeping a flat response, and we develop a compact flat-response neutron detector. The detector consists of two small spherical He proportional counters embedded at appropriate positions in a compact cylindrical polyethylene moderator. The sensitivity ratio between the two counters was adjusted to provide a flat response in the total outputs from the two counters. We demonstrated by MCNPX calculations and response measurements for Cf and Am-Be neutrons and monoenergetic neutrons that the present detector had a sensitivity comparable to long counters with a good flat response in a wide energy range up to 20 MeV while being only one-fifth of the weight of long counters. The positions of the effective center were determined as a function of neutron energy. We also proposed a method to evaluate the neutron energy using the detector, which will allow various new applications taking advantage of the ability to measure neutron fluence and energy at the same time.

• 出版日期2011-10