Influence of window effect of semiconductor x-ray detectors on the response function and detection efficiency

In order to search the dead layer of a Si(Li) x-ray detector, the jump ratio of the detection efficiency observed at the Si-K-edge energy was precisely measured by changing the incident photon energies at around 1.84 keV by using monoenergetic photons provided by SOR. Here, the dead layer is meant to be the Si region where the charge collection efficiency, η, is zero. As the result, the dead layers for two detectors investigated at present turned out to be absent. On the other hand, the Si front layers in which the charge collection is incomplete (0<η<1) were estimated to be 0.26 μm and 0.17 μm from a simple analysis for low energy tail spectrum. From these results, the effect of detector window on the response function and detection efficiency is discussed. (author)