Mobility-lifetime product of CdTe/CdZnTe crystals from charge collection efficiency of X-ray detectors

In this study we obtain the mobility-lifetime product of the material from the dependence of the average charge collection efficiency upon the bias voltage. We evaluate the efficiency by measuring the spectra for given sources. The measurement is based on monitoring the "energy locations" of known peaks. In the case of complete charge collection, a photon of energy E/sub ph/ yields an average 'packet' of electrons which is equal to E/sub ph//w where w is the ionization energy of the material. In practice, the collected electrons are integrated and converted to an analog voltage at the output of the charge sensitive preamplifier. The final reading is performed by an A/D converter at the output of the shaping amplifier and the reading is stored in the appropriate channel.