K-shell ionization cross sections for targets from Z=21 to Z=47 induced by He ions and by protons in the energy range 0.2-2.5 MeV/u.

Abstract

Absolute K-shell x-ray production cross sections have been measured for /sup 3/He ions in the energy range from 0.175 to 1.6 MeV/u incident on selected thin-foil targets from Ti (Z = 22) through Ag (Z = 47). A few measurements were made for incident /sup 4/He ions at energies from 0.2 to 0.6 MeV/u in order to study the effects of Coulomb deflection and retardation. Newly measured values are also reported for incident protons at energies from 0.5 to 2.5 MeV on numerous target elements from Sc (Z = 21) through Zn (Z = 30). The x-ray production cross sections were determined from x-ray yields normalized to simultaneous measurements of particle-scattering yields at 75/sup 0/. The K-shell ionization cross sections inferred from these results are compared with the predictions of the energy-loss Coulomb-deflection perturbed-stationary-state relativistic theory. There is agreement generally to within 10% although a systematic discrepancy, previously observed, is reproduced. Close agreement is obtained for protons with the reference values of Paul and Muhr (Phys. Rep. 135, 47 (1986)). This investigation is part of an overall experimental-theoretical program whose goals are (1) to enlarge the data base of ion-induced x-ray production cross sections by establishing accurate experimental values andmore » (2) to determine the limitations of the current theoretical descriptions of the inner-shell ionization process and their ability to calculate experimental quantities precisely.« less