XENON PRODUCTION CROSS-SECTIONS AT INTERMEDIATE ENERGIES AND PRODUCTION-RATES IN SMALL METEOROIDS BASED ON SIMULATION EXPERIMENTS

Thin-target production cross sections of xenon isotopes from barium we re determined at proton energies of 600 MeV, 800 MeV, 1200 MeV and 260 0 MeV using the CERN synchrocyclotron, LANL/Los Alamos and LNS/Saclay accelerators. The data thus obtained are compared with a priori thin-t arget production cross section calculations using code ALICE. Producti on cross sections for the neutron induced reactions are estimated theo retically. Together with the cross sections at low energies (less than or equal to 45 MeV) for the p-induced reactions on barium, determined by us earlier, the present data set provides a basis for evaluating t he cosmogenic xenon production rates in extraterrestrial matter. Furth er, the depth profiles for the production of stable xenon isotopes and Xe-127 radionuclide in 5 cm, 15 cm and 25 cm artificial meteoroids, i rradiated isotropically with 600 MeV protons, are determined experimen tally. These measured depth profiles are compared with theoretical est imates of the xenon production rates from barium in artificial meteoro ids, calculated by folding depth dependent spectra of primary protons, secondary protons and neutrons with the thin-target excitation functi ons for the underlying proton and neutron induced reactions. The produ ction rates thus obtained are compared with theoretical estimates usin g the depth profiles of well studied radionuclide production in meteor oids of various sizes. The measured xenon production ratios in the thi ck targets isotropically irradiated with 600 MeV protons and the calcu lated xenon production ratios in artificial meteoroids irradiated with realistic GCR energy spectrum are compared with those deduced from me teorite analysis and are found to be significantly different. The poss ible reasons for the discrepancy are explored. The refinements that ar e still necessary to accurately estimate xenon production rates in ext raterrestrial material are discussed.