CRITICAL CURRENT DENSITY IN NEUTRON IRRADIATED BULK YBa 2 Cu 3 O y

The magnetization curves of neutron irradiated bulk YBa 2 Cu 3 O y prepared by melt-textured growth method were measured from 1.5 to 85 K. Flux jumps were observed for H∥c at 6K. The anisotropies of critical current are analysed in detail- The pinning mechanism and physical model for flux jumps are discussed.