Experimental Study Of K-shell Ionization Cross Sections Of Ti Impacted By Positron Below 10 KeV

The experimental research on atomic inner-shell ionization cross sections by positrons impact is of great significance both in theoretical and practical applications.On the one hand,the accurate positron-impact ionization cross sections contribute to a better understanding of the interaction mechanisms of positrons with atoms,and promote the development of theoretical models for atomic inner-shell ionization by leptons impact.On the other hand,the positron-impact cross section data are also widely applied in many fields,such as improvement of the database used in simulation calculations,material analysis and nuclear fusion.However,the positron-impact ionization cross section data are very scarce,which seriously hinder the development of the theory.Since the measurements of atomic inner-shell ionization cross sections by positron impact are of great importance,the K shell ionization cross sections for Ti impacted by positron below 10 keV were measured in this paper.The main contents are as follows:(1)We applied an on-line monitoring technology to monitor the positron beam intensity impacted on the Ti target,which is using an HPGe detector to collect the annihilation y rays from the thick target induced by positrons in combination with the Monte Carlo simulations,and obtained the number of the incident positrons impacted on the target.(2)Since the multiple scattering of incident positrons,bremsstrahlung and annihilation photons and other secondary particles also contributed to the characteristic X-ray yields,thus we used the ratio of the theoretical calculation yields to simulated yields by Monte Carlo method to obtain correction factor,which is defined to correct these above effects.(3)Used ratio of theoretical yields to corrected experimental yields in combination with the DWBA theoretical ionization cross sections used in Monte Carlo simulations to obtain the Ti K shell ionization cross sections impacted by 8-9.5 keV positron.And they were compared with DWBA theoretical results and corresponding data published by others,it shows that the theoretical results were in a good agreement with our experimental data within the uncertainties and some discrepancies between our experimental data and the experimental data provided by other authors have also been discussed.