AMS MEASUREMENTS OF THIN-TARGET CROSS-SECTIONS FOR THE PRODUCTION OF BE-10 AND AL-26 BY HIGH-ENERGY PROTONS

In order to determine thin-target cross sections for the proton-induced production of residual nuclides from cosmochemically relevant target elements (Z less-than-or-equal-to 28), irradiation experiments were carried out with energies between 100 and 2600 MeV at various accelerators. For p-energies below 200 MeV the stacked-foil technique was used, while for higher energies individual thin targets were irradiated at 600, 800, 1200 and 2600 MeV. Using accelerator mass spectrometry, cross sections for the production of Be-10 from O, Mg, Al, Si, Mn, Fe and Ni and of Al-26 from Al, Mn, Fe and Ni were measured. The experimental data are compared with earlier literature data and the present status of the respective excitation functions is discussed. Theoretical cross sections for the reactions investigated were derived by Monte Carlo calculations on the basis of an intranuclear-cascade/evaporation (INC/E) model using the HERMES code system. For energies below 200 MeV, hybrid model calculations were performed using the code Alice Livermore 87. The calculated and experimental data are compared and the different production modes of Be-10 and Al-26 are discussed.