Bulk Performance of Improved Mercuric Iodide Nuclear Detectors

The bulk homogeneity of HgI2 detectors was evaluated by the nuclear spectral response of several detectors fabricated from the same iodine treated crystal grown by TOM (Temperature Oscillating Method) in a horizontal furnace. The 241 Am and 137CS spectral resolution is shown as a function of the detector thickness which ranges from 50 to 1000 ¿m and of the bias voltage. The lowest ¿T value for holes measured with 55Fe on these detectors is about 10-6 cm2V-l. Nevertheless, the spectral resolution for 137Cs indicates that these detectors must have spots with a higher value of ¿Th Uniformity studies by scanning one of the detectors with 241Am are also given and discussed. In addition a 60Co spectrum taken with a 1 mm thick HgI2 detector is shown for the first time.