J.B. le Grand

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Superconducting tunnel junctions (STJs) can be used as high-resolution high-count rate photon detectors. They are based on the measurement of the excess quasiparticle tunneling current caused by the absorption of a photon in one of the junction electrodes. We have fabricated Nb-Al-AlO/sub x/-Al-Nb tunnel junction detectors with different sizes and(More)
Fiske resonances have been measured in a rectangular Nb-Al, AlO/sub x/, Al-Nb Josephson junction as a function of the magnetic field applied parallel to a junction side. Due to the high quality factor of the junction, many resonant modes could be measured, using a special measuring technique. Each mode shows more lobes than reported before. The measured(More)
Experimental results are presented obtained with a cryogenically cooled high-resolution X-ray spectrometer based on a 141 x 141 micro m Nb-Al-Al(2)O(3)-Al-Nb superconducting tunnel junction (STJ) detector in an SR-XRF demonstration experiment. STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a(More)
Nb-based superconducting tunnel junctions are being developed as high energy resolution X-ray detectors. Unfortunately, loss of excess quasiparticles at the edges, combined with lateral diffusion, results in an inhomogeneous response. To study this degradation of energy resolution, we manufactured detectors with a Ta trap in the top or bottom electrode away(More)
In order to investigate the influence of quasi-particle trapping on the performance of superconductive tunnel junctions as X-ray detectors, a series of Nb/Al/Al/sub 2/O/sub 3//Al/Nb junctions have been produced with different Al-layer thicknesses in the bottom electrode. The proximity effect between the Nb absorber and the Al trapping layer plays a dominant(More)
Regions with reduced energy gap induced by the proximity effect give rise to quasi-particle loss in Josephson-junction X-ray detectors, but may also be used advantageously for quasi-particle collection. The influence of the thickness of the Al proximity layers in Nb/Al/sub 1/, AlO/sub x/, Al/sub 2//Nb Josephson tunnel junctions on the electrical(More)
We are developing high-resolution, broad-band, superconducting X-ray spectrometers for applications in materials science, astrophysics and biophysics. These spectrometers are superconducting microcalorimeters based on superconducting tunnel junction sensors made from thin films of niobium and aluminum. The energy resolution of these spectrometers can be(More)
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