Excitation functions of proton induced nuclear reactions on enriched 61Ni and 64Ni: Possibility of production of no-carrier-added 61Cu and 64Cu at a small cyclotron

Reference Cross Sections for Charged-particle Monitor Reactions

Production of 52Fe via proton-induced reactions on manganese and nickel

Production of no-carrier added 67Cu

In order to interpret cosmogenic radionuclides in extraterrestrial matter one has to differentiate between p- and α-induced reactions with solar (SCR) and with galactic (GCR) cosmic rays. Our earlier studies have shown that for a satisfactory description of GCR-interactions with dense matter rather few but characteristic high energy cross sections are required. In contrast, for the low and medium energy SCR-production a detailed knowledge of the respective nuclear reactions is needed. In the present study, excitation functions are presented for 39 p-induced reactions on Ni, Fe, Mn, Cr and Ti, which contribute to SCR-produced radionuclides (44≤A≤59) at energies up to 200 MeV. The excitation functions are based mainly on our own cross section measurements, partly on hybrid model predictions and to a lesser extent on experimental data from other authors. Based on these excitation functions, depth profiles for the proton induced SCR-production of46Sc,44Ti,48V,51Cr,52Mn,53Mn,54Mn,55Fe,56Co,57Co,58Co,60Co and59Ni from the 5 major targets mentioned before in extraterrestrial matter are calculated, assuming normal lunar surface conditions. Typical rigidities were adopted for the solar proton fluxes, ranging from 50 to 150 MV, which cover the rigidity values commonly observed in solar flares. In order to derive depth dependent p-fluxes from calculations of the energy loss of incoming particles, rather large differences in the respective chemical compositions had to be considered. The theoretical profiles are compared with experimental data from lunar samples, and several cosmochemical applications are discussed. They range from the study of single solar flare events by short-lived radioisotopes to the investigation of supposed long-term variations of the solar flare activity on a large times-cale of millions of years. The latter is possible by comparing the production rates of very long-lived nuclides (as for example53Mn with T=3,8·106 y) with that of short- or medium-lived nuclides. In this respect, the particular importance of44Ti (T-47.3 y) for measuring today's mean solar flare activity is pointed out. In general, the depth dependent production rates established in this work enable one to estimate the SCR-contributions to cosmogenic radionuclides from the respective target elements, thus providing a basis for a better understanding of the solar cosmic ray interaction with extraterrestrial matter.

M. Chiba

Papers

Nuclear reactions of nickel with protons up to 56 MEV