Calculation of transport cross sections for positrons in solid targets via improved expressions

Transport cross sections (TCS) for positron impinging on a number of selected atomic targets have been calculated in the energy range 1–4 keV. The calculations were performed by using a simplified correction of the approximate analytical expression of transport cross sections reported by Jablonski [A. Jablonski, Phys. Rev. B 58 (1998) 16470]. An argued parameter–obtained from both an exponential and polynomial fits–was then introduced. The agreement generally observed between our results and those previously reported in the literature is quite good, especially for positron energies greater than 2 keV. Furthermore, an attempt has been made for scaling the TCS with the atomic number of solid targets of interest. Such a scaling was found to be possible for both exponential and third order polynomial fits. The information gathered by the present study may be useful for the evaluation of parameters needed for quantitative low-energy positron annihilation spectroscopy.