A Study of Reactions of One and More Neutrons Photoemission from Bismuth

Abstract

The process of the photoemission of one, two, three and four neutrons from the ²⁰⁹Bi nuclei with producing, respectively, ²⁰⁸Bi, ²⁰⁷Bi, ²⁰⁶Bi and ²⁰⁵Bi daughter radioisotopes was investigated at the end-point energies of $E_{\gamma }^{{\max }}$ = 30 and 40 MeV of bremsstrahlung photons at the AANL (YerPhI) linear electron accelerator. Particularly, for the relative yields of ²⁰⁸Bi/²⁰⁷Bi, ²⁰⁶Bi/²⁰⁷Bi and ²⁰⁵Bi/²⁰⁷Bi the following values were obtained: 10.8 ± 2.2, 0.060 ± 0.002 and (1.45 ± 0.53)×10^–4 at $E_{\gamma }^{{\max }}$ = 30 MeV and 6.1 ± 0.5, 0.120 ± 0.006 and 0.0216 ± 0.0016 at $E_{\gamma }^{{\max }}$ = 40 MeV, respectively. It is shown that the predictions of the TALYS model, as well as the model which is contained in the GEANT4 package are in a contradiction with the experimental data. For instance, the predictions of GEANT4 at $E_{\gamma }^{{\max }}$ = 40 MeV for relative yields of ²⁰⁸Bi/²⁰⁷Bi and ²⁰⁵Bi/²⁰⁷Bi and the prediction of TALYS for ²⁰⁵Bi/²⁰⁷Bi about twice are smaller than the experimental values. At $E_{\gamma }^{{\max }}$ = 30 MeV, the predictions of both models for ²⁰⁵Bi/²⁰⁷Bi about two order of magnitude are smaller than the experimental values.