Analysis of the JINR p(660 MeV) + 129I, 237Np and 241Am measurements with eleven different models

Isotopically enriched 129I (85% 129I and 15%127I),237Np and 241Am targets were irradiated with a beam of 660 MeV protons at the JINR DLNP Phasotron and cross-sections of the formations of 207 residual products (74 from 129I, 53 from 237Np and 80 from 241Am) were generated. In this paper, we analyse the resultant data using 11 different models, realised in eight codes: LAHET (Bertini, ISABEL, INCL+ABLA and INCL+RAL), CASCADE, CEM95, CEM2k, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI and CEM2k+GEMINI. The purpose was to validate the tested models against the experimental data and to better understand the mechanisms for production of residual nuclei. The agreement of different models with the data varied quite a bit. We found that most of the codes were fairly reliable in predicting cross-sections for nuclides that were not too far away in mass from the targets, but that the codes differed greatly in the deep spallation, fission and fragmentation regions. None of the codes tested here except GEMINI allowed fission of nuclei as light as iodine. Thus, the 129I data, especially in the A 40-90 region, agreed best when the codes CEM2k and LAQGSM were merged with GEMINI. At the same time, GEMINI is not yet very reliable for an accurate description of actinides and the 237Np and 241Am data were better reproduced by LAHET (Bertini, ISABEL or INCL+RAL/ABLA), and by CEM2k or LAQGSM merged with GEM2. The 237Np and 241Am data were not so well-reproduced when using GEMINI. We conclude that none of the codes tested here were able to well-reproduce all the data and that improvements are needed. To this end, development of a better universal evaporation/fission model should be high priority. (authors)