Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements

Journal Article · Tue Dec 01 00:00:00 EST 2009 · Journal of Radioanalytical and Nuclear Chemistry, 282(3):703-708

DOI:https://doi.org/10.1007/s10967-009-0248-7· OSTI ID:972545

Keillor, Martin E; Aalseth, Craig E; Day, Anthony R; Fast, James E; Hoppe, Eric W; Hyronimus, Brian J; Hossbach, Todd W; Miley, Harry S; Seifert, Allen; Warren, Glen A

ABSTRACT Physics experiments, environmental surveillance, and treaty verification techniques continue to require increased sensitivity for detecting and quantifying radionuclides of interest. This can be done by detecting a greater fraction of gamma emissions from a sample (higher detection efficiency) and reducing instrument backgrounds. A current effort for increased sensitivity in high resolution gamma spectroscopy will produce an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and useful coincidence efficiencies. The system design is optimized to accommodate filter paper samples, e.g. samples collected by the Radionuclide Aerosol Sampler/Analyzer (RASA). The system will provide high sensitivity for weak collections on atmospheric filter samples, as well as offering the potential to gather additional information from more active filters using gamma cascade coincidence detection. The current effort is constructing an ultra-low-background HPGe crystal array consisting of two vacuum cryostats, each housing a hexagonal array of 7 crystals on the order of 70% relative efficiency per crystal. Traditional methods for constructing ultra-low-background detectors are used, including use of materials known to be low in radioactive contaminants, use of ultra pure reagents, clean room assembly, etc. The cryostat will be constructed mainly from copper electroformed into near-final geometry at PNNL. Details of the detector design, simulation of efficiency and coincidence performance, HPGe crystal testing, and progress on cryostat construction are presented.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 972545
• Report Number(s): PNNL-SA-67535; JRNCDM; NN2003000; TRN: US1001608
• Journal Information: Journal of Radioanalytical and Nuclear Chemistry, 282(3):703-708, Vol. 282, Issue 3; ISSN 0236-5731
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
AEROSOLS
CLEAN ROOMS
CONSTRUCTION
COPPER
CRYOSTATS
DESIGN
DETECTION
EFFICIENCY
GAMMA CASCADES
GAMMA SPECTROSCOPY
GEOMETRY
GERMANIUM
PHYSICS
RADIOISOTOPES
RESOLUTION
SENSITIVITY
TESTING
VERIFICATION
Ultra-Low-Background
Germanium
Coincidence Measurements Detecting and quantifying
Radionuclides
Low background gamma spectroscopy
High resolution gamma spectroscop Intrinsic germanium array
Gamma coincidence detection