Accurate modeling of the terrestrial gamma-ray background for homeland security applications

Sandness, Gerald A.; Schweppe, John E.; Hensley, W.K.; Borgardt, James D.; Mitchell, Allison L.

doi:10.1109/nssmic.2009.5401843

Cited by 23 publications

(26 citation statements)

References 1 publication

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“…The red curve is the sum of four 30 minute measurements. The blue curve is from the MCNP run of this case and is taken directly from the reference [Sandness, et al, 2011]. The output is for 10 11 source particles.…”

Section: Comparison Of Resultsmentioning

confidence: 99%

Transport Test Problems for Radiation Detection Scenarios

Shaver¹,

Miller²,

Wittman³

et al. 2012

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SummaryModeling forms an important component of radiation detection development, allowing for testing of new detector designs, evaluation of existing equipment against a wide variety of potential threat sources, and assessing operation performance of radiation detection systems. This can, however, result in large and complex scenarios which are time consuming to model. A variety of approaches to radiation transport modeling exist with complementary strengths and weaknesses for different problems. This variety of approaches, and the development of promising new tools (such as ORNL's ADVANTG) which combine benefits of multiple approaches, illustrates the need for a means of evaluating or comparing different techniques for radiation detection problems.This report presents a set of 9 test problems for comparing different types of radiation transport calculations, identifying appropriate tools for classes of problems, and testing and guiding the development of new methods. Cases are drawn primarily from existing or previous calculations with a preference for cases which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22. From a technical perspective, cases are chosen to span a range of difficulty and to include gamma transport, neutron transport, or both and represent different important physical processes and a range of sensitivity to angular or energy fidelity.Following test case identification, existing information about geometry, measurements, and previous calculations were assembled. Monte Carlo results (MCNP decks) were reviewed or created and re-run in order to attain accurate computational times and to verify agreement with experimental data, when present. Test case information was then conveyed to ORNL in order to guide testing and development of hybrid calculations. The results of those ADVANTG calculations were then sent to PNNL for compilation. This is a report describing the details of the selected test cases and results from available transport codes. Additional results from other transport codes will be added during the next year, along with additional cases if needed for software testing. Future work will extend the test problems to include more extensive crosscode comparisons as well as more refined metrics for evaluating the tradeoffs between operator time, computational time, and solution accuracy, to assemble a formalized benchmark set.v

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Section: Comparison Of Resultsmentioning

confidence: 99%

Transport Test Problems for Radiation Detection Scenarios

Shaver¹,

Miller²,

Wittman³

et al. 2012

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“…The blue curve-upper is from a smaller history (10 9 ) MCNP run of this case. The lower plots are taken directly from the reference [Sandness, et al, 2011]. The output is for 10 9 source particles, but the full statistics run assumed 10 11 source particles requiring an extrapolated runtime of 500 hours.…”

Section: Comparison Of Resultsmentioning

confidence: 99%

“…The output is for 10 9 source particles, but the full statistics run assumed 10 11 source particles requiring an extrapolated runtime of 500 hours. The lower blue curve is the sum of the direct and skyshine gamma rays from the soil as well as the smaller contributions from cosmic rays and radon in the air from [Sandness, et al, 2011] using 10 11 histories. The red curve is the measured spectrum.…”

Section: Comparison Of Resultsmentioning

confidence: 99%

Transport Test Problems for Hybrid Methods Development

Shaver¹,

Miller²,

Wittman³

et al. 2011

View full text Add to dashboard Cite

SummaryModeling forms an important component of radiation detection development, allowing for testing of new detector designs, evaluation of existing equipment against a wide variety of potential threat sources, and assessing operation performance of radiation detection systems. This can, however, result in large and complex scenarios which are time consuming to model. A variety of approaches to radiation transport modeling exist with complimentary strengths and weaknesses for different problems. This variety of approaches, and the development of promising new tools (such as ORNL's ADVANTG) which combine benefits of multiple approaches, illustrates the need for a means of evaluating or comparing different techniques for radiation detection problems.This report presents a set of 9 test problems for comparing different types of radiation transport calculations, identifying appropriate tools for classes of problems, and testing and guiding the development of new methods. Cases are drawn primarily from existing or previous calculations with a preference for cases which include experimental data, or otherwise have results with a high level of confidence, are non-sensitive, and represent problem sets of interest to NA-22. From a technical perspective, cases are chosen to span a range of difficulty and to include gamma transport, neutron transport, or both and represent different important physical processes and a range of sensitivity to angular or energy fidelity.Following test case identification, existing information about geometry, measurements, and previous calculations are assembled. Monte Carlo results (MCNP decks) are reviewed or created and re-run in order to attain accurate computational times and to verify agreement with experimental data when present. Test case information is conveyed to ORNL in order to guide testing and development of hybrid calculations. This is a report describing the details of the selected test cases; additional results from other transport codes will be added during the next two years, along with additional cases if needed for software testing. Future work will extend the test problems to include more extensive cross-code comparisons as well as more refined metrics for evaluating the tradeoffs between operator time, computational time, and solution accuracy, to assemble a formalized benchmark set.v

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“…As a side note, the cosmic-induced gammaray energy spectrum is expected to have an approximately E À 1.3 energy dependence below a few MeV, where E is the gamma-ray energy [7].…”

Section: Methodsmentioning

confidence: 99%

“…The helicopter was modeled at altitudes ranging from 100 ft. to 900 ft. in 100 ft. increments. A surface source was placed on top of the soil consisting of gamma rays from the K, U, and T background components developed from a previous background modeling effort [7]. The individual K, U, and T components of the detector response were tallied separately in the simulations, and the Gaussian energy broadening feature was applied, as implemented in MCNP.…”

Section: Determination Of Sensitivity Matrixmentioning

confidence: 99%

Real-time airborne gamma-ray background estimation using NASVD with MLE and radiation transport for calibration

Kulisek

Schweppe

Stave

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tHelicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this challenge, we have developed a new technique for real-time estimation of background gamma radiation from aerial measurements without the need for human analyst intervention. The method can be calibrated using radiation transport simulations along with data from previous flights over areas for which the isotopic composition need not be known. Over the examined measured and simulated data sets, the method generated accurate background estimates even in the presence of a strong, 60 Co source. The potential to track large and abrupt changes in background spectral shape and magnitude was demonstrated. The method can be implemented fairly easily in most modern computing languages and environments.

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Accurate modeling of the terrestrial gamma-ray background for homeland security applications

Cited by 23 publications

References 1 publication

Transport Test Problems for Radiation Detection Scenarios

Transport Test Problems for Radiation Detection Scenarios

Transport Test Problems for Hybrid Methods Development

Real-time airborne gamma-ray background estimation using NASVD with MLE and radiation transport for calibration

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