Ionization statistics in silicon X-ray detectors — new experimental results

This paper presents a systematic experimental examination of the response of silicon detectors to the absorption of soft X-rays. Measurements in the single photon counting mode with detector structures — especially designed and produced for this purpose — exposed to monochromatized synchrotron radiation with energies between 300eV and 1400eV at room temperature as well as at 140 K are shown. A well-fitting semi-empirical model for the response function of detectors with implanted entrance windows is developed. It decomposes the measured spectra into a Gaussian peak representing the full X-ray energy and a low energy background caused by incomplete charge collection close to the detector surface. The energy and temperature dependence of the mean energy required for the generation of one electron hole pair is extracted from the experimental data. In addition to the already known dependence on the detector temperature it is shown that the pair creation energy is also a function of the photon energy.