Comparison of the Total Cross Section of Ionization and Determination the Probability of Ionization forScattered Positrons to Helium Gas at Energy Range (300-2000ev)

The aim of this study is to find the total ionization cross section Q ion and the percentage probability of ionization P ion % for the positrons scattering from Helium Gas in the energy range (300-2000ev using first Born approximation when applying Bethe-Born theory in the range energy used. The results have shown that the change behaviorism of the total ionizationcross section Q ion decreases with the energy change. These results are in a good agreement with behaviorism changing the values of Q ion which were obtained by (Hwang et al) according to BEB model (The Binary-Encounter-Bethe Theory) for electrons scattering from Helium Gas in the same energy range allowable for both positrons and electrons, despite the different method through which the results have been obtained. Also, we observe a uniform change for increasing the values of percentage probability of ionization P ion % with increase in the energy which begins from highvalues at (66.5 %).