Pinning of Single Crystals of Niobium Irradiated at Helium Temperature

Abstract
The influence of neutron irradiation at 4.2 °K on the pinning of Abrikosov flux lines in single crystals of niobium was studied. It is shown that the irradiation with fast neutrons of 3.5 × 1012 cm−2 increases the mean value of the pinning force. Exposition of the specimen during 80 h at T = 100 °K and the recooling do not eliminate the irradiation effect. It is assumed that the observed increase in the pinning force is caused by additional pinning of dislocations available in the specimen (pinning‐centres) by point defects, formed during irradiation.