Spatially resolved study of superconducting tunnel junctions X-ray detectors by low temperature scanning synchrotron microscopy

Abstract

A low temperature scanning synchrotron microscope (LTSSM) has been developed for spatial analysis of superconducting tunnel junction X-ray detectors. One and two-dimensional images of the detector response to X-rays were measured by scanning the junctions kept at a working temperature of about 0.4 K with a highly collimated synchrotron radiation beam. The collimation was performed by inserting a pinhole mounted on a scanning unit into the synchrotron radiation in the range of 3-6 keV. The spatial resolution of the LTSSM is between 5 and 10 micrometer. The present results indicate a large discrepancy between the experimental spatial response and a quasiparticle diffusion and edge-loss model. The LTSSM plays an important role in the development of cryogenic X-ray detectors.

Energy Resolution of STJ X-Ray Detectors with Killed Electrode. Simple Model

“…The only exception is the series of the works performed by the lowtemperature scanning synchrotron microscope method [8,9]. The abnormal behavior observed in these works may be considered as an evidence of an additional mechanism of the resolution degradation which appears in STJ-detectors with large electrode sizes and deep quasiparticle traps.…”

Superconducting Tunnel Junction Detectors for Analytical Sciences

“…Although a quasiparticle diffusion and tunneling model predicts experimental spatial profile shapes, some of the physics remains unsolved. For example, the spatial profile for 5-keV photons can change with bias [17]. Since it is unlikely that the quasiparticle diffusion constant depends on the bias point, some unusual non-linear effects may be responsible [18].…”