Systematics of target and projectile $K$ -x-ray production and radiative electron capture for 20-80-MeV ${\mathrm{Cl}}^{q+}$ ions incident on 25-200-μg/ ${\mathrm{cm}}^2$ Cu targets

Journal Article · Fri Aug 01 00:00:00 EDT 1980 · Physical Review, A (General Physics)

DOI:https://doi.org/10.1103/PhysRevA.22.483· OSTI ID:1068162

Tanis, J. A.; Jacobs, W. W.; Shafroth, S. M.

A systematic investigation of K x-ray production for 20-80 MeV Cl ions in collision with thin self-supporting Cu targets has been conducted. Target and projectile characteristic x rays and radiative electron capture (REC) have been measured as a function of target thickness for incident charge states q < z{sub 1} - 2. At 80 MeV data were also obtained for q = z{sub 1}- 1. Large enhancements in both characteristic x-ray production and REC were observed for q = z{sub 1}- 1. Measured x-ray yields were parametrized vs. target thickness using the model of Betz et al. and least squares fits to the data were performed. Target K x-ray production for q<z{sub 1}-2 is described reasonably well by the CPSSR + ECR theory. For q=z{sub 1} - 1 the enhancement in the x-ray yield is predicted quite well by the method of Gray et al· The mean fluorescence yield for the highly stripped Cl ions is determined and found to increase by a factor of about six over the range 20-80 MeV, having a value (~0.1) nearly equal to the single K-vacancy value at 20 MeV. The radiative lifetime for the projectile ions is found to be ~3 x 10{sup -14} sec which is about three times longer than the single K-vacancy radiative lifetime calculated by Scofield. Parametrization of the REC yields vs. target thickness is used to normalize the measured REC intensity to the fraction of ions with K vacancies. Resulting REC cross sections are compared with the free-electron theory of Bethe and Salpeter and good agreement is obtained if it is assumed that each of the "loosely" bound electrons in Cu contributes equally to the REC process. By combining the results obtained for the characteristic x rays and REC, the fluorescence yield for K-shell capture events may be estimated, giving values in the range (2-4) x 10{sup -3} for the beam energies studied.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Accelerator& Fusion Research Division
• DOE Contract Number: DE-AC02-05CH11231
• OSTI ID: 1068162
• Report Number(s): LBL-10641; PLRAAN
• Journal Information: Physical Review, A (General Physics), Vol. 22, Issue 2; ISSN 0556-2791
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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