Alpha particle induced inner-shell ionization measurements for the undergraduate laboratory

The interaction of alpha particles with low atomic number elements has been studied in an attempt to determine the inner-shell ionization cross section. These cross sections were determined by measuring the characteristic x-rays that were produced when a thin aluminum target was bombarded by alpha particles from a 48 MBq {sup 244}Cm alpha source. The x-rays were detected with a Si(Li) x-ray detector whose resolution was 190 eV at 5.9 keV. The efficiency of the detector was determined from standard radioactive sources. The energies of the alpha particles were varied by placing thin Mylar absorbers between the alpha source and the target. The results are favorably compared to a current ionization theory given in such a form that an undergraduate physics major can do the calculations. This experiment is intended as an undergraduate laboratory experiment in the atomic or nuclear area.