A low-noise preamplifier for γ-ray sensors with add-on device for large-signal management

A new charge-sensitive preamplifier for High Purity Germanium γ-ray detectors has been built and tested. It comprises an over-load recovery device that reduces the dead time brought about by hits of energetic particles. The amplitude of the large signals is reconstructed from Time-Over-Threshold measurements performed along the reset transients. Using such a technology an extremely wide energy range of 10 keV to 30 MeV, or 70 dB, is obtained. With a count rate of 6 kHz a resolution of 1.1 keV fwhm is obtained on the 152Eu 122 keV line and of ∼5 perthousand on pulser lines in the energy range of 5-30 MeV.