Effective energy deposition and latent track formation of swift heavy ions in solids

Latent track formation in yttrium iron garnet (YIG) produced by high energy Ar ions is briefly reported at first. Then, in the framework of thermal spike model, a phenomenological parameter describing the effective energy transfer from excited electrons to lattice atoms, effective energy deposition Qeff, is deduced. Qeff is a function of ion velocity, electronic energy loss (Se) and mean free path λ of excited electrons in the matter, and is a time moderate term initialized by Waligorski's function of spatial energy deposition of secondary electrons ejected by incident ions. Size of ion latent track is proportional to Qeff value. From Qeff obtained by use of realistic λ values, the sizes of latent tracks in SiO2, YIG, Ti and Zr produced by given swift heavy ion irradiations are deduced and compared with experimental results. It is found that, from the fits to experimental results, the best λ values for SiO2, YIG, Ti and Zr and (6 ± 1), (8 ± 2), (6.1 ± 1.0) and (9.6 ± 1.0) nm, respectively. Moreover, the relationship between experimental damage and Qeff is discussed. (authors)