CHARGE-TRANSPORT AND SIGNAL GENERATION IN CDTE PIXEL DETECTORS

The current and charge signals on individual pixels of CdTe gamma-ray cameras are calculated. The time and position dependent free carrier d ensities following the absorption of a gamma-ray in the detector are f irst calculated by solving the continuity equations. These density dis tributions are then combined with the physical electric field and the pixel weighting field to provide the current induced through an indivi dual pixel from which the charge signal is also obtained. Simulations are made for various pixel sizes. These simulations confirm that the e nergy resolution of electron collecting pixel detectors must improve w hen smaller pixels are used since small pixels are less sensitive to h oles.