Charge collection physics in very large diameter germanium crystals

The Department of Energy (DOE) Office of Nuclear Physics builds and maintains germanium gamma-ray detector arrays at national laboratories and universities as user facilities. The scale, capability and cost of these detector arrays will greatly improve from the availability of larger single crystal and detector sizes. General statement of how this problem is being addressed Fundamental Czochralski crystal-growth parameters and techniques will be experimentally evaluated in the context of very large-diameter germanium crystal growth. In this manner, new crystal growth techniques will be evolved to make larger - diameter germanium detectors commercially available. What is to be done in Phase I The existing PHDS Co. high-purity germanium crystal growth system will be modified to accommodate alternative crystal growth techniques. The resulting large diameter crystals will be evaluated as pixelated gamma-ray detectors to provide high-fidelity spatial and spectroscopic information. These data will lead to an improved crystal - growth technique enabling much larger diameter commercial germanium detectors. Commercial Applications and Other Benefits Larger diameter detectors for nuclear physics detector arrays will be the first commercial product to evolve from this development. Following that will be larger- diameter detectors for nuclear fuel holdup measurements, environmental monitoring, nuclear weapons non-proliferation, treaty verification, nuclear explosion monitoring, and nuclear medicine.