A data acquisition and processing system for 3-D position sensitive CZT gamma-ray spectrometers

A PC-based data acquisition and processing system has been developed for tw o 3-D position-sensitive CZT gamma ray detectors. For each 3-D CZT detector , an integrated readout chip (VA1) is used to read out the signals from the 11x11 anode pixels. Two independent preamplifiers are used to read out the signals from the cathode and the grid electrodes that are used as trigger signals for low and high energy incident gamma rays, respectively. A PC-bas ed DAQ board samples the amplitudes of the signals from the anode pixels an d the cathode. The software collects and processes the energy spectra from the sampling data. The typical equivalent electronic noise of this system i s measured to be 6 keV and 7 keV for the two 3-D CZT detectors, and the dyn amic range of the system is up to 1 MeV. Spectra from 60, 122 and 662 keV g amma rays have been successfully measured using the two 3-D CZT detectors.