Parameters measurement for the thermal neutron beam in the thermal column hole of Xi’an pulse reactor

The distribution of the neutron spectra in the thermal column hole of Xi’an pulse reactor was measured with the time-of-flight method. Compared with the thermal Maxwellian theory neutron spectra, the thermal neutron spectra measured is a little softer, and the average neutron energy of the experimental spectra is about 0.042±0.01 eV. The thermal neutron fluence rate at the front end of thermal column hole, measured with gold foil activation techniques, is about 1.18×10 5 cm −2 s −1 . The standard uncertainty of the measured thermal neutron fluence is about 3%. The spectra-averaged cross section of 197 Au(n, γ) determined by the experimental thermal neutron spectra is (92.8±0.93) ×10 −24 cm 2 .