keywords CRITICAL CURRENT-DENSITY CU-O SYSTEM FAST-NEUTRON IRRADIATION FIELD PENETRATION DEPTH HIGH-TC SUPERCONDUCTORS II SUPERCONDUCTORS LAYERED SUPERCONDUCTORS MAGNETIC-RELAXATION Materials Science Materials Science, Multidisciplinary Physical Sciences Physics Physics, Applied Physics, Condensed Matter ROTATION EXPERIMENTS SINGLE-CRYSTAL YBA2CU3O7-DELTA Science & Technology Technology