[en] Defect buildup is investigated by the EPR method on irradiating single crystal silicon by 1 MeV Xe⁺ ions. The sample temperatures during irradiation are 23 and 150 deg C. The dose dependence of the defect number and their spatial distribution make it possible to draw the following conclusions: 1) Implantation of a single Xe⁺ ion at a room temperature is sufficient for formation of an amorphous region of approximately 25 A in diameter; 2) Increase in the substrate temperature during irradiation changes sharply the process and an amorphous layer forms on the sample surface. A new paramagnetic centre (VV-2-centre) is found, which produces an isotropic line in the EPR spectrum with g=2.009 and is observed on irradiating heated silicon samples only