Experimental Study of the Decay of Persistent Currents in a Soft Superconducting Ring Under α-Particle Irradiation
In a previous experiment, it was observed that the persistent current in a thin Pb superconducting ring decays when the material is subjected to α-particle irradiation from a Po210 source. Systematic observations of flux decay have been carried out under different experimental conditions. The effects of varying the temperature (from 1.1 to 4.2°K), the thickness of superconducting layers (from about 10 to 40 μ), and the materials (lead, tin, and indium) have been investigated. The flux decay law deduced from the experimental data seems to be logarithmic in time, showing a behavior similar to that observed by Kim et al. for flux creep in hard superconductors.