Cosmogenic Nuclide Production Rates Research Articles

The 7Li( p, n) 7Be reaction as a therapy neutron source, especially for smaller cyclotrons

Accelerator experiments at low and medium energies provide a basis for the development of models describing the production of cosmogenic nuclides by solar and galactic cosmic ray particles. Here, recent efforts to understand cosmogenic nuclide production are outlined taking their production in meteoroids as an example. Thin-target and thick-target experiments are described, by which the relevant cross sections are measured and in which the isotropic irradiation of meteoroids in space is simulated under completely controlled conditions. Thin-target and thick-target data are combined to develop and to validate model calculations of cosmogenic nuclide production rates by solar and galactic cosmic ray particles. The model calculations provide the basis to interpret the observed abundances of cosmogenic nuclides with respect to the exposure history of the irradiated matter and to the history of the cosmic radiation itself.

Spallation products distributed in a thick iron target bombarded by 3-Bev protons

The distribution of several spallation products, covering a wide range of atomic number, has been measured in a thick iron target (30×30×90 cm) bombarded by 3-bev protons at the Brookhaven cosmotron. Measurements were made of the radioactivity of γ-, β-, and X-ray emitters, either directly or after chemical separation, in iron and nickel foils placed at different depths. Products such as Co isotopes in Ni and Fe55, Mn54, and Cr51 in Fe, which are close to the target mass, were produced in important amounts at large angles to the primary beam. Production of nuclides of lower A showed gradually better collimation, Na22 and Be7 showing the smallest spread. These data provide useful information on the production rates of cosmogenic nuclides in meteorites and on their variation with depth and size. The results of this experiment may be compared with the available meteorite data and with other calculations.