A Single-Sphere-Multi-Detector Neutron Spectrometer

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					A Single-Sphere-Multi-Detector Neutron Spectrometer Hsiao-Hua Hsu1, and Jing Chen2 TechSource Inc., Santa Fe, NM 87594, USA 2 Radiation Protection Bureau, Health Canada 6302D1, Ottawa, Canada

A new neutron spectrometer is designed. It is a single-sphere-multi-detector spectrometer. 22 TLD600 chips and 21 58Ni foils are placed at specific locations in a CH 2 sphere with a diameter of 17 cm. The CH 2 sphere moderates incoming neutrons, so that each TLD chip has its unique response function to neutrons of various energies from thermal to 20 MeV. The reaction, 58Ni(n, p)58 Co, has a threshold of 0.497 MeV. Use of Ni foils can improve the detection of neutrons with higher energies. Response functions of TLD and Ni foils are calculated with MCNPX, and are used as the basis for this study. Comparing the new spectrometer to Bonner-sphere spectrometer, which has been used widely in many laboratories to measure neutron spectra, this new system has the following characteristics: 1) Both TLD chips and Ni foils are ‘integrated detectors’ that will record either discrete neutrons from a radioactive neutron source, or a large number of neutrons coming as a pulse. The usual detectors with Bonner-sphere system, such as 3 He and BF3, operated in counting mode, can not deal with pulsed neutrons. 2) This system does not need expensive electronics for measuring neutron spectra. Data analysis requires TLD reader and gamma ray spectrometer. 3) A single sphere system will occupy much less space compared with a set of Bonner spheres. 4) The new system can determine neutron spectrum more accurately than the systems with Bonner spheres. E-mail presenting author: Topic classification Preferred presentation jing_chen@hc-sc.gc.ca B4 Poster