Low Noise Front-end Electronics for a CZT-based Gamma-ray Spectrometer

Abstract

A low noise, low power consumption front-end electronics module, for the readout of cadmium zinc tellurium (CZT) detector, is presented in this paper. It is used for a high resolution gamma ray spectrometer aiming for in-situ environmental gamma ray measurements. The module consists of charge-sensitive amplifier (CSA), differential ADC driver, high voltage module and calibration module. Test results show that the rise time is about 31 ns. The noise with zero capacitance is 329e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> (0.053fC) and increases with a slope of 2.9 e <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> / pF in the range of less than 200 pF input capacitance, consistent with the simulation results. The input range of negative charge is up to 40 fC. The power consumption is about 80 mW per channel. It is relatively fast response, low noise, and low power consumption for the front-end electronics module with discrete components. A quasi-hemispherical CZT detector with the sensitive volume of 10 mm × 10 mm × 5 mm and the electronics module were used to obtain the spectrum of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs as the radioactive source. An energy resolution of 1.8% at 662 keV FWHM at the room temperature is obtained, without any discrimination methods, which is satisfied for our application.