QUASI-PARTICLE RELAXATION RATES IN NB ALOX/NB TUNNEL-JUNCTIONS DUE TOABRIKOSOV VORTICES/

Superconducting tunnel junctions are promising detector elements in ne xt generation x-ray, UV, and optical detectors, Quasiparticles which a pproach the neighborhood of the normal core may scatter and emit a pho non, thus being trapped in the Abrikosov vortex (AV). In this way the existence of AVs reduces the lifetime of quasiparticles. In this exper iment excess quasiparticles in a Nb/AlOx/Nb junction are created by me ans of a low temperature scanning electron microscope. The trapping ra te of quasiparticles into AVs is determined by measuring the quasipart icle lifetime as a function of the AV concentration. This results in a n effective trapping radius of the AV of 14.8 +/- 1.4 nm, which is sli ghtly less than theoretical expectations. (C) 1997 American Institute of Physics.