Hrymalo A. Determination of the total neutron cross sections of the 52Cr and natHf at the filtered neutron beams

The thesis is devoted to the determination of the averaged total neutron cross sections of 52Cr and natHf on filtered neutron beams. The measurements were carried out on horizontal experimental channels (HEK-8 and HEK-9) of the Kyiv research reactor WWR-M of the Institute for Nuclear Research. Proportional helium CHM-37 and hydrogen LND-281 counters were used for neutron registration. The main method of investigation was a transmission method. The results of measurements of the total neutron cross section of 52Cr at the energies of 7.5, 55, 52, 48.4 and 44.2 keV are presented in the thesis. Neutron beams with the energies of 55, 52, 48.4, and 44.2 keV are forming at scattering of the filtered neutrons with the average energy of 59 keV on hydrogen nuclei at the angles 15, 20 25, and 30 °. At these energies, a set of the averaged transmissions and, accordingly, a set of the averaged total neutron cross sections are obtained. The resonance parameters 52Cr at the energy E0 = 50.156 keV with spin J = 1/2, the neutron resonance width Гn = 1.529 keV, the radiation width Гγ = 641.7 meV are determined from this set of transmissions (the resonance parameters are taken from the ENDF / B-VII library). The obtained difference in the cross sections of the 52Cr, natHf and the 52Cr resonance parameters with the results of the experimental data from EXFOR database, with evaluated data from the evaluated nuclear data libraries and theoretical calculations obtained by the TALYS-1.8 code are explained.