Precise measurement techniques for establishment of fast neutron standards and their applications

In this report, the comprehensive study on the precise measurement and the critical analysis of the neutron fluence and emission rate caused by the reaction T(D, n)α and the spontaneous fission of a Cf-252 source is described. Special emphasis was laid upon the establishment of the national standards for fast neutron fluence and emission rate. Such standardized neutron field is to be used as the absolute reference for the determination of neutron reaction cross section, the calibration of neutron detectors, radiotherapy, radiation protection, the study on material damage and so on. Also the measurement of neutron and gamma-ray doses absorbed in water was studied by spectrometry, and the results were compared with those of Boltzmann transport calculation. The characteristics and the classification of standard neutron fields, the survey of neutron standardization research, the establishment of a 14 MeV neutron standard field and the measurement of the standard reaction cross section of Fe-56(n,p)Mn-56, the absolute measurement of neutron and gamma-ray energy spectra in water with a 14 MeV neutron source, the measurement of the neutron emission rate of Cf-252 by circulating manganese bath method and the analysis of pulse time response for setting up the fast neutron spectrum standard field with a central cavity are reported. (Kako, I.)