Speaker
Description
We present results from a new x-ray and gamma-ray spectrometer with continuous sampling of detector
signals. The system was designed for Compton scatter collimation with up to 4 detector crystals of
cadmium zinc telluride (CZT of 20mm x 20mm x 10mm). Here, we report on the capability to sample
positive and negative polarity charges from detector electrodes at programmable sampling frequency.
This feature is important for the use with other room-temperature semiconductor detectors like
germanium, TlBr3, and CsPbBr3 (CPB). Using Cs-137 gamma-rays and a CZT with 121 pixelated anodes at
room-temperature, we measure energy resolution of 4keV FWHM, i.e., 0.60% FWHM at 661.7keV for 121
pixels (100%). The system allows one to measure positive and negative charge polarity in the range
from -700fC to +700fC. With CZT, we find that 50-MHz sampling speed is well suited, and we demonstrate
sampling at 25MHz, 12.5MHz, and 6.25MHz which would suit “slower” detector materials, like TlBr3 and
CPB. The sampling readout of signals from anodes and cathodes allows one to measure the exact location
of Compton-scatter interactions in the detector crystal which enables Compton scatter collimation.
Possible applications are high-resolution energy spectroscopy and imaging of radiation from a distance.
