Transition temperature depth profiling of Cs-137 gamma-irradiated YBCO ceramic

The transition temperatures depth profiling for YBa2Cu3O7-delta superconduc ting samples irradiated with 662 keV gamma rays is presented in this paper. Before irradiation, a quite homogeneous distribution of critical temperatu re and transition width was observed. This distribution after the irradiati on process appears inhomogeneous in all material volume. The surface direct ly exposed to the source shows an improvement of the superconducting proper ties, while the transition temperature values measured on the opposite surf ace practically did not change. The spatial distribution of the gamma radia tion deposited doses inside the irradiated samples was simulated using the Monte Carlo method. The results obtained by the simulation are in good corr espondence with the experimental data. The possible effects of the energy d istribution inhomogeneity on the experimentally measured properties are ana lysed in the text. (C) 2001 Elsevier Science B.V. All rights reserved.