Twin shaping filter techniques to compensate the signals from CZT/CdTe detectors

A Gamma Ray Burst Monitor (GRBM) has been proposed to form part of the LOBSTER experiment, approved by ESA for a Phase A study for a future flight (2009) aboard the International Space Station (ISS). The GRBM detector would be based on CdZnTe array modules, maintained, together with the front-end electronics, at a temperature of about 250 K by using Peltier effect or passive cooling systems. To improve the detector performance several hardware (HW) and software (SW) techniques are being tested. In addition to the strip readout technique for rejecting charged particles interacting with the detector, we have investigated a method which employs a pair of active filters (one slow and one fast) to analyze differently shaped signals from the same charge sensitive preamplifier. This technique could be particularly useful for application with multi-element detection systems requiring dedicated front end and readout integrated circuits (ASICs) especially designed for the implementation of the HW correction procedure. Some experimental results are presented from the application of the biparametric technique on CdZnTe/CdTe detectors with planar and segmented electrodes in order to study the influence of the correction parameters and to verify the efficiency of the correction algorithm on groups of neighboring pixels.