Measurement of K-Shell ionization cross sections of Al by 4–9 keV positron impact

Abstract

In this paper, the K-shell ionization cross sections of Al by 4–9 keV positron impact have been measured for the first time. Firstly, the K-shell characteristic X-ray yields produced by positron collision with thick Al target were measured. In this process, online monitoring technology was developed to obtain the accurate number of incident positrons that collided with the thick Al target, and spectrum smoothing technology was introduced to obtain the accurate Kαβ characteristic peak net counts generated by positron collision with the thick Al target. Next, combined with Monte Carlo (MC) simulation and theoretical calculation, the contributions of the multiple scattering of incident positrons, from the bremsstrahlung and annihilation photons and other secondary particles to the experimental characteristic X-ray yields were corrected. Finally, the corrected experimental characteristic X-ray yields were converted into K-shell ionization cross sections by the numerical calculation method. The theoretical values of the distorted wave Born approximation (DWBA) were compared with the experimental results of the Al K-shell ionization cross sections by 4-9 keV positron impact. The result shows that the predicted values of DWBA theory slightly overestimate the experimental results, but the trend is basically consistent with them.