Abstract
L subshell X-rays of 48Cd and 49In have been measured for the impact of protons with energies from 75 to 250 keV. Obviously, it is found that Lγ2 (abbreviation Lγ2,3 for 48Cd and Lγ2,3,4 for 49In) X-ray emission is enhanced in comparison with Lγ1 X-ray emission. The relative intensity ratios of Lγ2 to Lγ1 X-ray are larger than the atomic data and increase with decreasing proton energy. This is caused by the multiple ionization of outer-shell electrons. To verify this explanation, the enhancements for relative intensity ratio of Lι and Lβ2 to Lα X-ray in experiments are discussed, and the direct ionization cross sections of 4d, 5s, and 5p electrons are calculated using BEA theory.
Highlights
IntroductionX-ray emission, an important consequential result from ionatom collisions, involves several inner-shell processes, from primary inner-shell ionization by the incident ions up to the subsequent vacancy decay, including intrashell transitions
X-ray emission, an important consequential result from ionatom collisions, involves several inner-shell processes, from primary inner-shell ionization by the incident ions up to the subsequent vacancy decay, including intrashell transitions.e detailed knowledge of X-ray emission provides important information to understand the charged ion-atom interaction mechanism and to test relevant ionization theories [1,2,3,4]
E maximum projected range of the proton in the present work is 1.45 μm and 1.65 μm for Cd and In, respectively. ose are all shorter than the target thickness. e experimental target can be taken as a thick target. e X-ray production cross section can be derived to measure the X-ray yield and the proton’s stopping power [24]. e principal uncertainties for the experimental data result from the X-ray count statistics 5%, incident ions recording 3%, detector efficiency 10%, solid angle 2%, slope calculation of the experimental yield curve 2%, and stopping power calculation 10%. e maximal uncertainty of the yield is about 12%, that of the ratio of the subshell X-rays is about 14%, and that of X-ray production cross section is about 16%
Summary
X-ray emission, an important consequential result from ionatom collisions, involves several inner-shell processes, from primary inner-shell ionization by the incident ions up to the subsequent vacancy decay, including intrashell transitions. Multiple ionization, which means more than one orbital electron is knocked off during ion-atom collisions, can be caused by concurrent direct single ionization or subsequent Coster–Kronig (CK) or Auger transitions. Such action can reduce the screening of nuclear charge and alter the fluorescence yield because of the absence of some outer-shell electrons. As we all know that such multiple ionization can be induced by heavy ions [9,10,11,12], that has been tested and verified in our previous work [13,14,15] This can be produced by relativistic electron impact and is dependent on the incident energy [16,17,18]. E maximum projected range of the proton in the present work is 1.45 μm and 1.65 μm for Cd and In, respectively. ose are all shorter than the target thickness. e experimental target can be taken as a thick target. e X-ray production cross section can be derived to measure the X-ray yield and the proton’s stopping power [24]. e principal uncertainties for the experimental data result from the X-ray count statistics 5%, incident ions recording 3%, detector efficiency 10%, solid angle 2%, slope calculation of the experimental yield curve 2%, and stopping power calculation 10%. e maximal uncertainty of the yield is about 12%, that of the ratio of the subshell X-rays is about 14%, and that of X-ray production cross section is about 16%
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