The initial rate of carrier removal and the growth of mobility in heavily doped silicon irradiated by low-energy particles are considered. The quantitative description of these effects are given. A new method is proposed to determine the cross-section for formation of radiation defects in such materials from the value of saturation of the initial rate of carrier removal at high levels of doping. The experimentally estimated values of the cross-sections are discussed. 36 refs.; 6 figs.