Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements

Nelson, Noel; Azmy, Yousry; Gardner, Robin P.; Mattingly, John; Smith, Ralph; Worrall, L. G.; Dewji, S.

Title: Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements

Abstract

Detector response functions (DRFs) have become the subject of increasing scientific interest for the last thirty years in several industrial applications of radiation detection. These applications include gamma-ray, prompt gamma-ray, and X-ray spectrometry for elemental analysis and location as applied to mining, radio-tracing in medicine, and holdup source characterization. However, it is difficult to create a rigorous mathematical formulation of the DRF. Therefore, semi-empirical and stochastic approaches have been developed instead to construct detector and application specific DRFs. A DRF can be considered to be a function that converts the energy-dependent incidence of incoming source particles onto a detector into a detector response spectrum that simulates the experimental response. The DRF can also be used in the reverse sense in an inverse problem setting, as a step in the process of predicting the physical characteristics of an unknown source (e.g. the holdup problem and library spectra). Much of the recent work on DRFs has been performed by Gardner. He has developed accurate DRF models through semi-empirical curve fitting and Monte Carlo simulation. His DRFs for 3" X 3" NaI detectors have been developed with the experimental measurements taken by Heath and for 6"x6" bare (unshielded) NaI(Tl) detector data with single-energymore »« less

Authors:

Nelson, Noel ^[1]; Azmy, Yousry ^[1]; Gardner, Robin P. ^[1]; Mattingly, John ^[1]; Smith, Ralph ^[2];

^[3];

^[3]

North Carolina State Univ., Raleigh, NC (United States). Dept. of Nuclear Engineering
North Carolina State Univ., Raleigh, NC (United States). Dept. of Mathematics
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Publication Date:: Sun Jun 07 00:00:00 EDT 2015

Research Org.:: North Carolina State University, Raleigh, NC (United States). Consortium for Nonproliferation Enabling Capabilities (CNEC); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE National Nuclear Security Administration (NNSA), Office of Nonproliferation and Verification Research and Development (NA-22)

OSTI Identifier:: 1440585

Grant/Contract Number:: AC05-00OR22725; 127981; NA0002576

Resource Type:: Accepted Manuscript

Journal Name:: Transactions of the American Nuclear Society

Additional Journal Information:: Journal Volume: 112; Conference: American Nuclear Society Annual Meeting, San Antonio, TX (United States), 7-11 Jun 2015; Journal ID: ISSN 0003-018X

Publisher:: American Nuclear Society

Country of Publication:: United States

Language:: English

Subject:: 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; NaI collimated detector; Response function; Validation; Uncertainty quantification; Holdup measurements

Citation Formats


                    Nelson, Noel, Azmy, Yousry, Gardner, Robin P., Mattingly, John, Smith, Ralph, Worrall, L. G., and Dewji, S. Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements.  United States: N. p., 2015. 
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                    Nelson, Noel, Azmy, Yousry, Gardner, Robin P., Mattingly, John, Smith, Ralph, Worrall, L. G., & Dewji, S. Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements.  United States.

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                    Nelson, Noel, Azmy, Yousry, Gardner, Robin P., Mattingly, John, Smith, Ralph, Worrall, L. G., and Dewji, S. Sun .  
"Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements".  United States.  https://www.osti.gov/servlets/purl/1440585.

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@article{osti_1440585,

  title        = {Validation and uncertainty of DRF's for a 1"×2" NaI collimated detector for radioisotope holdup measurements},

  author       = {Nelson, Noel and Azmy, Yousry and Gardner, Robin P. and Mattingly, John and Smith, Ralph and Worrall, L. G. and Dewji, S.},

  abstractNote = {Detector response functions (DRFs) have become the subject of increasing scientific interest for the last thirty years in several industrial applications of radiation detection. These applications include gamma-ray, prompt gamma-ray, and X-ray spectrometry for elemental analysis and location as applied to mining, radio-tracing in medicine, and holdup source characterization. However, it is difficult to create a rigorous mathematical formulation of the DRF. Therefore, semi-empirical and stochastic approaches have been developed instead to construct detector and application specific DRFs. A DRF can be considered to be a function that converts the energy-dependent incidence of incoming source particles onto a detector into a detector response spectrum that simulates the experimental response. The DRF can also be used in the reverse sense in an inverse problem setting, as a step in the process of predicting the physical characteristics of an unknown source (e.g. the holdup problem and library spectra). Much of the recent work on DRFs has been performed by Gardner. He has developed accurate DRF models through semi-empirical curve fitting and Monte Carlo simulation. His DRFs for 3" X 3" NaI detectors have been developed with the experimental measurements taken by Heath and for 6"x6" bare (unshielded) NaI(Tl) detector data with single-energy sources centered on the detector face at a distance of 10 cm. There was agreement with the Heath benchmark detector measurements within two Poisson standard deviations of the measured data. DRFs have also been developed for other detectors such as high purity Germanium detectors and Si(Li) for the same geometries as NaI. Other than a few artifacts such as backscatter peaks, there was good agreement between simulated responses and the experimental data.},

  doi          = {},

  journal      = {Transactions of the American Nuclear Society},

  number       = ,

  volume       = 112,

  place        = {United States},

  year         = {Sun Jun 07 00:00:00 EDT 2015},

  month        = {Sun Jun 07 00:00:00 EDT 2015}

}

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Figures / Tables:

Fig. 1: Measured and normalized computed responses for the HEU disc source at y=41 cm and (a) on-axis, x=0 (b) x=10 cm right of center, and (c) x=20 cm right of center.

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