L-subshell ionization of heavy elements by carbon and nitrogen ions of energy 0.4–1.8 MeV/amu

Abstract

L-shell x-ray production and subshell ionization cross sections have been measured for 0.4 -1.8-MeV/amu carbon and nitrogen ions for selected heavy elements with 72 & Z~~90. The results yre compared with the predictions of the ECPSSR theory [perturbed-stationary-state (PSS) theory with energyloss (E), Coulomb deflection (C), and relativistic (R) corrections] describing both direct ionization and electron-capture processes and the semiclassical approximation (SCA} calculations for direct ionization.For both theories significant deviations are found for L2-subshell ionization in the low-energy range.The multiple ionization of outer shells was studied by comparing L x-ray intensity ratios measured for heavy ions and protons. The ionization probabilities of the N4 subshell at zero impact parameter was extracted from these data. Measured ionization probabilities are compared with the predictions of the SCA theory and the "geometrical model. " The inAuence of multiple ionization on the measured Lsubshell cross sections is discussed.

Effects of multiple ionization and intrashell coupling inL-subshell ionization by heavy ions

“…Originally, the number of additional vacancies in higher subshells was deduced from the measured x-ray en- [18,19]. In the energy range that overlaps with our present work for C → Pt and Au, following Berinde et al [20], Semaniak et al [15] derived the probabilities for ionization of M and N subshells from changes in relative L x-ray peak yields once protons were replaced with carbon ions. While, with Larkins scaling [21] to deduce the number of multiple vacancies from energy shifts and relative intensities redistribution, this approach evolved into a standard procedure [22], Pajek et al [23] demonstrated that changes in both position and width of x-ray peaks are the most reliable determinants of the outer-shell ionization probabilities.…”

“…The L-subshell ionization cross sections for 4.8-21.6-MeV carbon on Pt and Au by Semaniak et al [15] were already corrected for effects of multiple ionization; unfortunately, the measured x-ray production cross sections were not given in Ref. [15]. Table IV lists other cross sections found in the literature for gold, after correction for multiple ionization with Eqs.…”

“…We found no carbon-induced L-subshell cross sections in the literature for comparison with our Re data. The L-subshell ionization cross sections for 4.8-21.6-MeV carbon on Pt and Au by Semaniak et al [15] were already corrected for effects of multiple ionization; unfortunately, the measured x-ray production cross sections were not given in Ref. [15].…”

“…Table I lists the measured x-ray production cross sections. From these measurements and the data of others for gold [12][13][14][15] and platinum [15], L-subshell ionization cross sections, Li ͑i =1,2,3͒, will be extracted for comparison with predictions of the ECPSSR theory and its modifications. In terms of Li , the x-ray production cross sections can be calculated as follows:…”

Measurement of L Shell X-Ray Production and Average L Shell Fluorescence Yields for Some Heavy Elements at 123.6 keV

“…Doǧan et al [21] have measured L l , L α , L β and L γ X-ray fluorescence cross-sections using two different energies 59.5 and 123.6 keV. In some studies, targets were excited with X-ray tube [22][23][24][25][26], protons [27][28][29][30], electrons [31][32][33] and ions [34][35][36][37] as an alternative to radioisotopes.…”