Performance of a large area mercuric iodide lung counter

A new detector system based on mercuric iodide technology was designed and constructed specifically for in vivo measurement applications. The system contains four mercuric iodide room-temperature semiconductor detectors, each with an area of 25 mm×25 mm, for photon detection and spectrometry. The combination of multiple matched detectors in a single housing achieves the large area needed for in vivo measurements, while overcoming the inherent limitations in the growth of large, high quality crystals of high-Z semiconductor materials. The use of large semiconductor detectors operating at room temperature eliminates the need for liquid nitrogen cooling required for germanium detectors which presents a potential danger in the confined space characteristic of in vivo measurements. The high quality room temperature detectors preserve the spectroscopic quality requirements for transuranic detection. The performance of the mercuric iodide in vivo detector meets the performance requirements specified in ANSI N 13.30, and compares satisfactorily with the performance of germanium detector systems typically used for in vivo lung measurements