Neutron transmission measurement and simulation of Ta-181 for neutron resonance thermometry

Hara, Kaoru*; Asako, Minoru*; Kai, Tetsuya   ; Sato, Hiroaki*; Kamiyama, Takashi*

To develop an imaging technique of neutron resonance thermometry with tantalum (Ta)-181, the neutron transmission spectrum for a tantalum foil (30 or 300 micro-meters in thickness) which was set up in a constant temperature furnace was measured by the time-of-flight method. Several temperature conditions were set from 20 to 500 degree Celsius. The measurements were performed on the BL10 of MLF at J-PARC. To cutoff neutrons below thermal neutron energy, a cadmium filter was inserted on the neutron beam line. The measured neutron transmission spectrum in the eV energy region was compared to the calculated one with the PHITS code. In the calculation, the time distribution of neutron emission from a source was defined as the pulse function of BL10. The evaluated nuclear data of ENDF/B-VIII.0 or JENDL-4.0 were utilized for each calculation with respect to the neutron-induced nuclear reactions of Ta-181. The differences of both results are discussed based on the measured spectra.