Hybrid gas counter with CdTe active wall for C-14 dating system

In order to upgrade an anticoincidence type gas proportional counter for a ¹⁴C dating system to measure samples less than 1 gram we developed a small hybrid gas counter. The CdTe detectors were applied as the wall of the gas counter and at the same time serve as an anticoincidence guard counter to reduce the background. The simulation result showed an anticoincidence efficiency above 99.0% for a noise level up to 70 keV in CdTe detectors. The performance of the counter has been investigated through experiments and the obtained anticoincidence ability is about 70% with 21% lost in the holes for the path of the center wire and existing slots between every two CdTe detectors.