  Track radii Re induced by swift heavy ions are studied. The experimental
track data are analyzed in Gd2Ti2O7 pyrochlore in the range Se=6-54 keV/nm (Se
- electronic stopping power) including irradiations by low and high velocity
ions. The Analytical Thermal Spike Model (ATSM) is applied whose main features
are reviewed. The track data of Gd2Ti2O7 exhibit scaling features which mean
simple quantitative relationships with track sizes of other insulators
controlled only by a single materials parameter (MP), the melting temperature
Tm. The Re2-Se track evolution curve is described in the whole range of Se
without the application of any individual fitting parameter and MPs apart Tm;
the threshold for track formation Set=6.1/14.4 keV/nm for E<2 MeV/nucleon and
E>8 MeV/nucleon, respectively. The unique role of Tm is a highly important
limitation for the mechanism of track formation. The practical consequences of
the results are discussed with respect of the estimation of irradiation
parameters
