Abstract
Hysteresis loops measurements have been performed for various GdBa2Cu3O7 high temperature superconducting samples irradiated with various does of gamma radiation. Magnetic measurement at low temperatures (close to 4 K) revealed initial gradual increase in the pinning force and critical current density with gamma does. These measurements also revealed non-monotonic changes in the pinning force close to the transition temperature. Very little reduction in the transition temperature has been observed with gamma dose. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.