Coaxial Ge(Li) Gamma-Ray Camera

A γ-ray camera utilizing a position sensitive coaxial Ge(Li) detector is being developed. Slots parallel to the detector axis are machined in the outer n-layer contact of the crystal to produce effectively independent pie-shaped sectors. The sector preamplifier-discriminator that is activated by a γ-ray interaction in the detector specifies the angular position of the interaction. The radial location of the interaction is determined by pulse-shape analysis of the signal from the common broadband low-noise preamplifier connected to the p-core. Thus, with an appropriate collimator the spatial distribution of radiation intensities is determined in polar co-ordinates . Position signals corresponding to one or more selected γ-ray energies are stored in a small computer which transforms the polar co-ordinates into cartesian coordinates and displays the image on an X-Y oscilloscope. Data pertaining to the position response of the detector and to regional variations in detector efficiency are presented.