Detection characteristics of an ultralow‐energy measurable pure‐germanium detector in the hundreds‐eV photon‐energy region

In the energy range from 1 keV down to a few hundred eV, a newly developed ‘‘ultralow‐energy measurable’’ pure‐Ge detector for a pulse‐height analysis and a current‐mode observation has been characterized using synchrotron radiation monochromatized by a grasshopper monochromator at the Photon Factory of the National Laboratory for High Energy Physics (KEK). X‐ray measurements in this low‐energy region were previously tried out using several types of ‘‘windowless’’ Si(Li) detectors. These detectors, however, had trouble, including temporal variations in the quantum efficiencies because of their detector‐surface deteriorations due to various impurities in vacuum chambers. Our pure‐Ge detector has a 4000‐A thick polymer window metalized by a 1400‐A thick Al supported by a 100‐μm apart Si‐ribbed structure. However, for this liquid‐nitrogen‐cooled detector with the special window, its actual energy‐response data are not available at this time. Therefore, the investigations of its characteristics are reported p...