Response of Ge photon detectors to beta-rays and possible reduction of photopeak areas due to beta–gamma coincidence summing effects

• The possible effects arising from β–γ and X–CE coincidence summing are shown.
• A spectrum of CEs was measured without absorbers, positioned close to detector window.
• Results suggest that β-absorbers are required in γ-spectrometry to eliminate coincidences with electrons.

In the use of photon detectors having sensitivity to β-rays or internal conversion electrons (CEs), β–γ and/or X–CE coincidence summing may arise. In particular, an n-type germanium detector has a thin dead layer and window, causing considerably higher sensitivity to β-rays and/or CEs especially when sources are located at a small source-to-detector distance. In the present research, reduction of the photopeak area due to β–γ or X–CE coincidence summing has been studied for three germanium detectors.