Year
2005
Abstract
Lung counter systems are used to monitor the presence of nuclear isotopes in the lungs of personnel, which by accident or improper working practices may have inhaled these materials. Presently high-purity germanium (HPGe) detectors with liquid nitrogen cooling are used as the detecting system for the radiation emitted by these isotopes. Recently an array of four mercuric iodide (HgI2) detectors, each 25 mm x 25 mm in area, has been assembled and tested for this application. The main advantage of the mercuric iodide array is that the detectors operate at ambient temperatures, so that the system is less heavy, more rugged, and does not require liquid nitrogen cooling. The construction of the array, together with the electrical layout and the routing of the signal processing will be shown. The results of tests on a phantom system will be described and discussed. Expansion of the array to 16 detectors (which will have the same or greater sensitivity than the presently existing systems) is planned and a conceptual drawing is shown. This design will result in a portable unit that can be used in the field at locations of accidents or the unauthorized release of radioactive materials.