Abstract
Using the activation technique without chemical separation, cross sections for the production of 119 fission products—from \({}^{72}\) Zn to \({}^{151}\) Pm—belonging to 32 different chemical elements (Zn, Ga, Ge, As, Br, Se, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm) were measured under independent irradiation of two metallic \({}^{232}\) Th foils with 20.9 MeV protons. The irradiations were carried out at the NS-20M facility, based on the I-2 linear proton accelerator, and lasted 1 hour and 1 minute. The proton flux was determined using monitor reactions \({}^{\textrm{nat}}\) Cu( \(p,x\) ) \({}^{62}\) Zn and \({}^{\textrm{nat}}\) Cu( \(p,x\) ) \({}^{63}\) Zn. The obtained results, together with data from other authors available in the EXFOR database and our previously measured data (also included in EXFOR) for proton energies of 100, 200, 800, 1200, and 1600 MeV, are presented in the form of excitation functions and mass yield curves. The \({}^{232}\) Th fission product cross sections were modeled using the PHITS-3.31 code with the INCL4.6/GEM, JAM/GEM, and Bertini/GEM models for 42 proton energies in the range from 0.01 to 3 GeV. Cumulative cross sections for fission products in the mass range \(72<A<151\) were computed using custom software based on the independent cross sections obtained from PHITS-3.31 output. For selected proton energies (20.9, 100, 200, 800, 1200, and 1600 MeV), a comparison between calculated and experimental results was performed using standard statistical criteria ( \(\bar{F}\) , \(\Delta\bar{F}\) and \(\langle F\rangle\) ), allowing evaluation of the predictive performance of each model implemented in PHITS-3.31. In addition, the GEF2023/2.1 code was used to analyze the mass yields of \({}^{232}\) Th fission products.
