Photon energy dependence of spatial non-uniformity in super-conducting tunnel junction detectors between 200 ev and 10 keV

It has been demonstrated by Low-Temperature Scanning Synchrotron Microscope that the spatial profiles of Nb/Al/AlOx/Al/Nb detectors are abnormally large in an energy range between 2 and 10 keV, and thus the detectors produce no clear total absorption peaks. Below 2 keV, on the other hand, full illumination experiments have afforded the evidence that the spatial uniformity is significantly improved, for example, an 100 μm square junction has an intrinsic energy resolution of 5.4 eV at 200 eV. These results reconfirm that carefully designed junction detectors with a reasonable size are ideal for energy-dispersive spectroscopy in a soft X-ray range.