Backscattering of positrons from thick targets

The empirical equation for the backscattering coefficient of monoenergetic positrons impinging normally on thick targets is found. This equation is expressed by the η(Z, T) function of the target atomic number for 6 ⩽ Z ⩽ 79 in the energy region from 0.1 to 20 MeV. The values of η(Z, T) are found by computer calculation with the use of the “segment model”, which was verified by comparison with the experimental data for electrons. The calculated backscattering coefficients of electrons and positrons show a significant difference, especially in the high-energy region and for high-Z materials.