Spatial and temporal dynamics of superconducting Nb/AlO/sub x//Nb tunnel junction detectors

Nb/AlO/sub x//Nb tunnel junction detectors have been irradiated locally with electrons having energies in the range between 6 and 35 keV. By the measurement of the temporal and spatial dynamics of the detector response the characteristic time and length scales of the radiation-induced nonequilibrium state were obtained. The spatially resolved measurements show the importance of the coupled diffusion of the quasi-particles and phonons in the junction electrodes and the wiring and of the phonon propagation in the substrate material. The observed temporal and spatial detector response gives constraints for the development of superconducting-tunnel-junction particle detectors with improved efficiency and energy resolution.<>