The novel approach described in this proposal has the potential to dramatically reduce the cost of high resolution, transportable room temperature radiation detectors. Recent experiments, performed by the principal investigator, have shown that xenon gas near the critical point (298.4K, 57.5atm.) provides an ideal medium for radiation detection. The results have shown that the energy resolution of a room temperature xenon ionization chamber is superior to both sodium iodide (NaI) scintillation detectors and liquid xenon ionization chambers and approaches that of cryogenically cooled Germanium (Ge) detectors. In addition, xenon possess excellent scintillation properties with an efficiency near that of NaI. Recent work in liquid xenon (185K, 3atm.) has investigated using the scintillation pulse for event triggering and background discrimination. A room temperature xenon detector incorporating both scintillation and electron pulse analysis has the potential to provide the academic, research, environmental and industrial institutions with a low cost, high resolution radiation detector for medium energy photons (50keV-2.0MeV). We are proposing to generate experimental data on the scintillation characteristics of high pressure xenon gas used in an ionization chamber. We will modify a newly developed xenon gas ionization chamber with the capability to measure the scintillation pulse during operation and characterize the pulse to operational parameters of the chamber.The development of a low cost, high resolution, portable, room temperature, gamma radiation detector will have unlimited applications for mapping and identifying hazardous spaces and radioactive material in the environment, for use in astrophysics to measure and identify stellar radiation sources, and will provide an invaluable research tool for studies in radioactive materials and devices. There are essentially two current radiation detectors available for commercial application. The scintillation type (NaI) are low cost but have a distinct disadvantage of having low resolution, while the solid state types (Ge) are capable of high energy resolution but are very costly and require cryogenic cooling. Our detector will provide a system which is not only low cost but possesses high energy resolution.
