Determination of the Neutron Flux at the IREN Facility

The IREN complex for neutron physics research was constructed at the Frank Laboratory of Neutron Physics based on a linear accelerator of electrons up to an energy of 50 MeV. Measurements of the neutron flux density in a wide range of energies (from thermal to fast) are required in various experiments. This is done by neutron activation analysis with high-resolution gamma spectroscopy. In order to determine the flux of resonant neutrons more accurately, one needs to calculate the effective resonance integrals with specific features of the real neutron spectrum and the thermal motion and absorption of neutrons in the sample taken into account. A program for computation of effective resonance integrals has been developed for this purpose. The effective resonance integrals for ¹⁹⁷Au, ⁹⁵Zr, ⁹⁷Zr, and ⁶³Cu are calculated using this program. The values differ considerably from the ones given in reference literature. These results are used to more accurately determine the flux density of neutrons.