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

Abstract

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 themore » detector design, simulation of efficiency and coincidence performance, HPGe crystal testing, and progress on cryostat construction are presented.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
972545
Report Number(s):
PNNL-SA-67535
Journal ID: ISSN 0236-5731; JRNCDM; NN2003000; TRN: US1001608
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Radioanalytical and Nuclear Chemistry, 282(3):703-708; Journal Volume: 282; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
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

Citation Formats

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, and Warren, Glen A. Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements. United States: N. p., 2009. Web. doi:10.1007/s10967-009-0248-7.
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. Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements. United States. doi:10.1007/s10967-009-0248-7.
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, and Warren, Glen A. 2009. "Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements". United States. doi:10.1007/s10967-009-0248-7.
@article{osti_972545,
title = {Design and Construction of an Ultra-Low-Background 14 Crystal Germanium Array for High Efficiency and Coincidence Measurements},
author = {Keillor, Martin E. and Aalseth, Craig E. and Day, Anthony R. and Fast, James E. and Hoppe, Eric W. and Hyronimus, Brian J. and Hossbach, Todd W. and Miley, Harry S. and Seifert, Allen and Warren, Glen A.},
abstractNote = {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.},
doi = {10.1007/s10967-009-0248-7},
journal = {Journal of Radioanalytical and Nuclear Chemistry, 282(3):703-708},
number = 3,
volume = 282,
place = {United States},
year = 2009,
month =
}
  • State-of-the-art treaty verification techniques, environmental surveillance, and physics experiments require increased sensitivity for detecting and quantifying radionuclides of interest. This can be accomplished with new detector designs that establish high detection efficiency and reduced instrument backgrounds. Current research is producing an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and sensitive {gamma}--{gamma} coincidence detection. The system design is optimized to accommodate filter paper samples, e.g. samples collected by the Radionuclide Aerosol Sampler/Analyzer. The system will provide high sensitivity for weak collections on atmospheric filter samples (e.g.<10{sup 5} fissions) as well as offering the potential to gather additionalmore » information from higher activity filters using gamma cascade coincidence detection. The first of two HPGe crystal arrays in ultra-low-background vacuum cryostats has been assembled, with the second in progress. Traditional methods for constructing ultra-low-background detectors were followed, including use of materials known to be low in radioactive contaminants, use of ultra-pure reagents, and clean room assembly. The cryostat is constructed mainly from copper electroformed into near-final geometry at Pacific Northwest National Laboratory. Details of the detector assembly and initial background and spectroscopic measurement results are presented; also a description of the custom analysis package used by this project is given.« less
  • The goal of searching for zero-neutrino double-beta (0{nu}{beta}{beta}) decay is to probe an absolute neutrino mass scale suggested by the mass-splitting parameters observed by neutrino oscillation experiments. Furthermore, observation of 0{nu}{beta}{beta} decay is an explicit instance of Lepton-number non-conservation. A sensitive measurement of two-neutrino double-beta (2{nu}{beta}{beta}) decay can provide critical input to Quasiparticle Random Phase Approximation (QRPA) calculations of the nuclear matrix elements in models similar to those used to extract the absolute neutrino mass from (0{nu}{beta}{beta}) decay experiments. Tellurium-130, an even-even nucleus, can undergo 2{nu}{beta}{beta} decay to the first 0+ excited state of {sup 130}Xe producing three possible {gamma}-raymore » cascades as it transitions to the ground state. The Cascades detector is a high purity germanium (HPGe) crystal array consisting of two ultra-low-background copper cryostats each housing a hexagonal array of seven crystals. The project is currently being developed at Pacific Northwest National Laboratory in Richland, WA (USA), and aims to obtain very high {gamma}-ray detection efficiency while utilizing highly effective and low-background shielding. GEANT4 simulations of the detector are performed for a {sup 130}Te sample in order to determine the optimum size and geometry of the source for maximum detection efficiency and predict its sensitivity for measuring 2{nu}{beta}{beta} decay to the first 0+ excited state of {sup 130}Xe. These simulations are validated with calibration sources and presented.« less
  • State-of-the-art treaty verification techniques, environmental surveillance, and physics experiments require increased sensitivity for detecting and quantifying radionuclides of interest. This can be accomplished with new detector designs that establish high detection efficiency and reduced instrument backgrounds. Current research is producing an intrinsic germanium (HPGe) array designed for high detection efficiency, ultra-low-background performance, and sensitive {gamma}-{gamma} coincidence detection. The system design is optimized to accommodate filter paper samples, e.g., samples collected by the Radionuclide Aerosol Sampler/Analyzer. The system will provide high sensitivity for weak collections on atmospheric filter samples (e.g., < 10{sup 5} fissions), as well as offering the potential tomore » gather additional information from higher activity filters using gamma cascade coincidence detection. The first of two HPGe crystal arrays in ultra-low-background vacuum cryostats has been assembled, with the second in progress. Traditional methods for constructing ultra-low-background detectors were followed, including use of materials known to be low in radioactive contaminants, use of ultra-pure reagents, and clean room assembly. The cryostat is constructed mainly from copper electroformed into near-final geometry at Pacific Northwest National Laboratory. Details of the detector assembly and initial background and spectroscopic measurement results are presented; also a description of the custom analysis package used by this project is given.« less
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