Experimental study of the Ho165(n,2n) reaction: Cross section measurements for the population of the Ho164 ground state and isomeric state from the threshold up to 20 MeV

Abstract

In the present work the $^{165}\mathrm{Ho}(n,2n)$ reaction was studied experimentally and theoretically for the population of the ground state (${J}^{\ensuremath{\pi}}={1}^{+}$) of the $^{164}\mathrm{Ho}$ product nucleus, as well as for the population of its isomeric state (${E}_{ex}=139.8$ keV, ${J}^{\ensuremath{\pi}}={6}^{\ensuremath{-}}$). The cross sections of both the ground and isomeric state channels were measured at energies near the reaction threshold (${E}_{th}=8.04$ MeV), at 10.1, 10.4, and 10.7 MeV, as well as at energies higher than 17 MeV, at 17.1, 18.1, 19.0, and 19.6 MeV. The adopted method was the activation technique relative to the $^{197}\mathrm{Au}(n,2n)^{196}\mathrm{Au}$ and $^{27}\mathrm{Al}(n,\ensuremath{\alpha})^{24}\mathrm{Na}$ reference reactions. The quasi-monoenergetic neutron beams for the near threshold energies were produced via the $^{2}\mathrm{H}(d,n)^{3}\mathrm{He}$ reaction, while for the neutron beams above 17 MeV the $^{3}\mathrm{H}(d,n)^{4}\mathrm{He}$ reaction was utilized. In both cases the deuteron beams were delivered by the 5.5 MV Tandem Van de Graaff accelerator of the Institute of Nuclear and Particle Physics at N.C.S.R. ``Demokritos''. Additional to the experimental study, calculations were performed using the talys code (v. 1.9). The experimental data of the present work along with the previous measurements were compared with the talys results so as to investigate the reproduction of the experimental data for the different level density models of the code.