Parameter measurement of thermal neutron beam in thermal column of Xi'an pulse reactor

The distribution of the neutron spectra in the thermal column of Xi'an pulse reactor was measured with the time of flight method in this paper. Comparing with the thermal Maxwellian theory neutron spectra, the thermal neutron spectra measured in experiment is a little softer, and the average neutron energy in measurement spectra is about 0.042 ± 0.01 eV. The thermal neutron fluence rate at the front end of the thermal column, preliminarily measured with gold foil activation techniques, is about 1.18 x 105 cm-2·s-1. The standard uncertainty of the measured thermal neutron fluence is about 3%. (authors)