Polycrystalline mercuric iodide detectors

Abstract

ABSTRACT Polycrystalline mercuric iodide nuclear radiation detectors have been prepared using different ceramic fabrication methods, such as hot pressing, hot wall vapor phase deposition and screen printing. Areas varying between0.01 to 100 cm2 and thicknesses varying between 30 to 600 microns, have been fabricated. Gold or carbon electrodes were deposited having the shape of single continuous, linear strip or square pixel contacts and tested fortheir response to lower and higher gamma energy and beta particles. The rr value is of the order of iO cm2/V forboth holes and electrons and therefore can act as particle counter without energy resolution. The low production costfor potential large detector area make these compounds interesting for certain imaging applications.Keywords: imaging, x-ray, polycrystalline, mercuric iodide 1. INTRODUCTION The best known radiation detectors which operate at room temperature are Si, Hg12, CdTe, Cd1 ZnTe, GaAs andlately also polycrystalline diamond. The energy per electron-hole pair formation, W, is 3.6, 4.2, 4.4, 4.5, 4.7 and14 eV respectively. Thus polycrystalline Hg12 which has a high atomic number Z, wide band gap and low Wcompetes favorably with the other semiconductors for radiation particle counting and imaging where spectralresolution is not needed. The basic properties of Hg12 nuclear radiation detectors are summarized in recent book'and the technology of single crystal Hg12 detectors is described in the first chapter of this book2 .