A Mercuric Iodide Gamma-Ray Spectrometer

Crystals of HgI2 (Eg = 2.1 eV) have been operated as conductign type Ω-ray spectrometers at room temperature. Two-carrier collection is observed and collection of the electrons is sufficiently good to give full energy peaks for γ-rays of energies below 100 keV. A resolution of 10 keV FWHM was observed for the 18 keV X-ray from 241Am Room temperature spectroscopy in the energy region < 100 keV is possible due to the high stopping power of HgI2 (Z = 80, 53) and the low dark conductivity {~10-13(Ω. cm)-1). With the present material the mobility-lifetime product is 10-5 to 10-4 cm2/V for electrons and is 10-6 to 105 cm2/V for holes.