Rugged High-Resolution Xenon Gamma-Ray Spectrometer

70794 Monitoring the non-proliferation of nuclear weapons requires the detection of penetrating radiation emitted by nuclear materials (NM). Gaseous ionization chambers, based on collecting the charge produced by the ionizing radiation inside the detecting medium, are widely used to detect this radiation. To eliminate the dependence of pulse-height distribution at points of interaction, the volume of the ionization chamber is usually divided into two parts by a screening grid. However, signals read out from the gridded ionization chamber are extremely sensitive to micro-vibrations of the grid, leading to an additional low-frequency noise component. In addition, the grid makes the ionization chamber very fragile. This project will develop a rugged, high-resolution xenon cylindrical ionization chamber. Compared to conventional cylindrical ionization chambers with a screening grid, the proposed detector will be less sensitive to mechanical vibrations and acoustic noise, and will have a simpler design at a reduced production cost. At the same time, the new detector will retain a large size, large mass (several kilograms) of working medium, and excellent energy resolution (< 2% FWHM at 662 keV). Phase I will construct a prototype of the high-pressure, Double-Anode Cylindrical Ionization Chamber (DACIC) and demonstrate that a double-wire anode inside a cylindrical ionization chamber filled with high-pressure (>50 atm) Xe can provide the desired energy resolution. Commercial Applications and Other Benefits as described by the awardee: The proposed detector could be used to measure gamma rays and neutrons in nuclear material monitoring systems, special systems targeted to detect and identify the presence of weapon grade plutonium, in situ gamma-spectroscopy of liquid radioactive waste, well-logging, and gamma-ray imaging.