Electron beam lithography and reactive ion etching were used to fabricate diffraction gratings with periods between 70 and 110 nm. The gratings were formed in a thermally grown SiO2 layer and used as substrates for aluminum–aluminum oxide–gold tunnel junctions. The light emission from the tunnel junctions under direct-current bias conditions is due to the scattering of the surface plasmon polaritons (SPPs). In particular, by isolating the scattering of the slow mode SPP off the gratings the dispersion relation of the slow mode was determined.

The ability of detectors to automatically recover (self-recovery) in a short period of time after sensing a particle is a very valuable advantage for their use as microvertex detectors at high energy particle colliders. Using a superconducting strip detector made of granular tungsten, we have observed such behavior with pulse amplitudes of few 100 μV and recovery times fo 10–50 ns. A 1.8 μm wide thin film was used to detect the superconducting-to-normal transitions induced by the absorption of 55Fe, 6 keV X-rays. For high bias currents the detector did not self-recover and a constant efficiency estimated to ∼65% was found, but with good indications that such a rate would persist in the self-recovery mode at lower bias currents. The threshold between self-recovering and propagating hotspots is discussed within the thermal propagation model, developed previously for normal regions which bridge the width of the strip. These results also confirm the potential applications of superconducting strips for high resolution X-rays detectors.

Irradiation of granular aluminum (g-Al) superconducting strips by betas with energies in the minimum-ionizing range has demonstrated a high detection efficiency. An efficiency of almost 70% was found for 0.5 μm wide g-Al strips operating at a temperature of 1.4–1.7 K. This is a very encouraging result for this new concept of a high-resolution tracking detector, which could be used in future colliding-beam accelerators such as the proposed Superconducting Super Collider or other large hadron colliders. As was found earlier with X-ray irradiation, the experiments are accurately described by our thermal-propagation model.