Composition-independent temperature induced by swift heavy ions in insulators and its relation with track formation

A systematic study of the $R_e$-$T_m$ relation ($R_e$ = track radius, $T_m$ = melting temperature) in insulators reveals new features of track formation. A quantitative relationship is demonstrated between $R_e$ values measured in various solids when $⟨s_e⟩$=constant ($⟨s_e⟩$ = atomic stopping power). This effect is the consequence of a composition-independent, identical maximum temperature distribution $\Delta T(r,0)$, which is induced in various insulators in a narrow cylindrical volume close to the tracks. The uniformity ceases gradually at larger distances. $\mathrm{\Delta }T(r,0)$ has a Gaussian shape, with a constant width w=4.5 nm, is independent of materials parameters and it can be determined experimentally by the measurement of Re in various insulators when $⟨s_e⟩$=constant. The consequences of the experimental $\mathrm{\Delta }T(r,0)$ distribution are discussed.