High-purity n-type material was bombarded with 238Pu  particles or 252Cf fission fragments (with average energies of 5.48 and 80MeV, respectively). The doses were such that there was no overlap of the ion tracks. The generation of Frenkel pairs was studied via the numerical simulation of a cascade of collisions with Si lattice atoms. This simulation was carried out for light ions ( particles) and heavy ions (fission fragments). Deep levels which arose in the Si band-gap were studied by means of transient spectroscopy. The system of deep levels was the same for both light and heavy ions. An observed 1000-fold difference in the effects of fragments and  particles was explained in terms of the recombination conditions of primary Frenkel pairs in the ion tracks.

A.M.Ivanov, I.N.Ilyashenko, N.B.Strokan, B.Schmidt: Fizika i Tekhnika Poluprovodnikov, 1995, 29[3], 543-52 (Semiconductors, 1995, 29[3], 281-5)