Astatine production in a lead-bismuth target bombarded by a proton beam: a detailed study using INCL4.6-Abla07
Résumé
Liquid lead-bismuth eutectic (LBE) is often considered as a possible target in spallation neutron sources. An
experiment has been performed in 2005 at ISOLDE (CERN), in which LBE has been irradiated by 1.0 and 1.4
GeV protons and isotopes of astatine, a volatile precursor of Po, have been found. Until recently no model
was able to reproduce this astatine production, which is due either to double charge exchange reactions,
Bi(p,π-xn)At, or to secondary reactions induced by helium nuclei. Recently, both parts of the spallation model
combination INCL4-Abla have been improved leading to the new versions, INCL4.6-ABLA07. In particular,
an additional mechanism to produce light and intermediate mass fragments has been added and special care
has been paid to the low energy reactions. This paper first shows that all the basic features of the different
reactions leading to astatine production are well predicted by the new model. The model, implemented into a
beta version of MCNPX2.7 is then used to simulate the ISOLDE experiment. A very good agreement with the
experimental data is observed.