Production of radiotoxic isotopes in LBE spallation targets: Recent extensions of the INCL4 model and experimental validation

Recent extensions of the Liège intranuclear cascade (INCL) model concerning the mean field of the baryons, the pion sector and a refinement of the Pauli blocking for the first collision have led to an improved description of the production of radiotoxic isotopes induced by protons in thin targets. In this paper we have investigated the production of some highly radiotoxic isotopes in thick target. With this aim, the INCL4 model implemented in the MCNPX code has been modified. We have adapted the ALEPH code to perform the evolution of a spallation target. The standard INCL4 model and our modified INCL4 version were compared to the experimental results measured at PSI with a stack of lead and bismuth disks. The same conclusion drawn from thin target results is also obtained. In thin and in thick spallation targets, the production of the highly radiotoxic 209Po and 208Po isotopes is reduced. In thick targets, the production of 210Po and of 210mBi are feeded by (n,γ) reactions and are not affected by the recent extensions.