Critical temperature of Nb3Sn change at nonuniform distribution of radiation defects

Irradiation of thin-film Nb3Sn samples of different thickness by H+ ions with the energy of 75 keV at sample holder temperatures of 12 and 300 K is performed. Critical temperatures of irradiated saples are measured as a function of ionic irradiation fluence. It is shown experimentaly, that in the case when a value of projective path of ions in Nb3Sn is greated than sample thickness, variation of its critical temperature after irradiation is not dependent on temperature conditions of irradiation. In the case when sample thickness exceeds a value of projective path, i.e. radiation defects are distributed nonuniformly in material thickness, heating of irradiated samples from 12 up to 300 K results in critical temperature variation. This fact is explained by the process of radiation defect diffusion migration. The possible mechanism of such migration is suggested; and evaluation of migration energy is presented