Validation of energy-weighted algorithm for radiation portal monitor using plastic scintillator

Lee, Hyun Cheol; Shin, Wook; Park, Hyo Jun; Yoo, Do Hyun; Choi, Chang Il; Park, Chang Su; Kim, Hong Suk; Min, Chul Hee

doi:10.1016/j.apradiso.2015.10.019

Cited by 20 publications

(11 citation statements)

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“…In case of 137 Cs having a Compton edge at 0.477 MeV theoretically, it was already observed that the peak of the energyweighted spectrum that originated from the Compton maximum was a feature for nuclide identification in previous studies. Similarly, 60 Co having a clear Compton maximum of the energy spectrum at 1.041 MeV also exhibited a discernable peak in the energy-weighted spectrum [8][9][10][11]. Figs.…”

Section: Spectrum Analysis Of Moving Sourcesmentioning

confidence: 76%

“…The energy-weighted algorithm proposed in the previous studies multiplies the counts in each energy bin and the energy corresponding to the same channel (in the form of a coefficient) using the following equation: (1) where is the energy-weighted count of the energy spectrum's i th bin, is the original optical photon count in the i th bin, and is the energy coefficient in the i th bin [8][9][10][11]. Applying the equation, it was observed that the increased area, such as the Compton maximum of the gamma energy spectrum measured by the plastic scintillator, was converted into an identifiable peak as shown in Fig.…”

Section: Improvement Of Energy-weighted Algorithmmentioning

confidence: 99%

“…The Pacific Northwest National Laboratory (PNNL) has reported that several gamma sources such as 137 Cs or 60 Co have demonstrated an intrinsic Compton maximum in their energy spectrum [7]. Based on the physical properties of plastic scintillators, we had earlier proposed an energy-weighting algorithm that emphasizes the Compton maximum in the form of a peak by multiplying the counts per channel of the energy spectrum with the energy of the corresponding channel [8][9][10][11]. Using this algorithm, we could distinguish among 137 Cs, 60 Co, 226 Ra, and 22 Na in a lab-scale experiment.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Source Identification Method Based on Energy-Weighting Level with Portal Monitoring System Using Plastic Scintillator

et al. 2020

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Background: Radiation portal monitors (RPMs) involving plastic scintillators installed at the border inspection sites can detect illicit trafficking of radioactive sources in cargo containers within seconds. However, RPMs may generate false alarms because of the naturally occurring radioactive materials. To manage these false alarms, we previously suggested an energy-weighted algorithm that emphasizes the Compton-edge area as an outstanding peak. This study intends to evaluate the identification of radioactive sources using an improved energy-weighted algorithm. Materials and Methods: The algorithm was modified by increasing the energy weighting factor, and different peak combinations of the energy-weighted spectra were tested for source identification. A commercialized RPM system was used to measure the energy-weighted spectra. The RPM comprised two large plastic scintillators with dimensions of 174 × 29 × 7 cm 3 facing each other at a distance of 4.6 m. In addition, the in-house-fabricated signal processing boards were connected to collect the signal converted into a spectrum. Further, the spectra from eight radioactive sources, including special nuclear materials (SNMs), which were set in motion using a linear motion system (LMS) and a cargo truck, were estimated to identify the source identification rate. Results and Discussion: Each energy-weighted spectrum exhibited a specific peak location, although high statistical fluctuation errors could be observed in the spectrum with the increasing source speed. In particular, 137 Cs and 60 Co in motion were identified completely (100%) at speeds of 5 and 10 km/hr. Further, SNMs, which trigger the RPM alarm, were identified approximately 80% of the time at both the aforementioned speeds. Conclusion: Using the modified energy-weighted algorithm, several characteristics of the energy weighted spectra could be observed when the used sources were in motion and when the geometric efficiency was low. In particular, the discrimination between 60 Co and 40 K, which triggers false alarms at the primary inspection sites, can be improved using the proposed algorithm.

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Section: Spectrum Analysis Of Moving Sourcesmentioning

confidence: 76%

Section: Improvement Of Energy-weighted Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluation of Source Identification Method Based on Energy-Weighting Level with Portal Monitoring System Using Plastic Scintillator

et al. 2020

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“…A simpler method identifies isotopes by finding peaks in the energy/channel weighted spectra, which occur at the point of the Compton edge for isotopes with significant Compton continuums, such as 137 Cs, hence characteristic photopeak energies can be calculated using the Compton scattering equation [76]. In isotopes where the spectra contains multiple low-energy γs and there exists no readily discernable Compton edge, such is the case with 238 U, there still exists a characteristic peak in the energy weighted spectrum which can be determined experimentally.…”

Section: Source Characterisation Based On Energy Considerationsmentioning

confidence: 99%

Current and Prospective Radiation Detection Systems, Screening Infrastructure and Interpretive Algorithms for the Non-Intrusive Screening of Shipping Container Cargo: A Review

Connolly

Martin

2021

JNE

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The non-intrusive screening of shipping containers at national borders serves as a prominent and vital component in deterring and detecting the illicit transportation of radioactive and/or nuclear materials which could be used for malicious and highly damaging purposes. Screening systems for this purpose must be designed to efficiently detect and identify material that could be used to fabricate radiological dispersal or improvised nuclear explosive devices, while having minimal impact on the flow of cargo and also being affordable for widespread implementation. As part of current screening systems, shipping containers, offloaded from increasingly large cargo ships, are driven through radiation portal monitors comprising plastic scintillators for gamma detection and separate, typically 3He-based, neutron detectors. Such polyvinyl-toluene plastic-based scintillators enable screening systems to meet detection sensitivity standards owing to their economical manufacturing in large sizes, producing high-geometric-efficiency detectors. However, their poor energy resolution fundamentally limits the screening system to making binary “source” or “no source” decisions. To surpass the current capabilities, future generations of shipping container screening systems should be capable of rapid radionuclide identification, activity estimation and source localisation, without inhibiting container transportation. This review considers the physical properties of screening systems (including detector materials, sizes and positions) as well as the data collection and processing algorithms they employ to identify illicit radioactive or nuclear materials. The future aim is to surpass the current capabilities by developing advanced screening systems capable of characterising radioactive or nuclear materials that may be concealed within shipping containers.

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“…Therefore, various spectral processing techniques have been reported for pseudo gamma spectroscopy of plastic scintillation detectors. Energy windowing [1][2][3][4], F-score analysis [5], energy weighted algorithms [6,7], and inverse matrix [8] are representative methods for pseudo gamma spectroscopy. However, these methods can be categorized as indirect pseudo gamma spectroscopic methods because it is impossible to directly identify the energy of incident gamma rays.…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of Compton Edges in Plastic Gamma Spectra Using Deep Autoencoder

Jeon

Lee

Moon

et al. 2020

Sensors

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Plastic scintillation detectors are widely utilized in radiation measurement because of their unique characteristics. However, they are generally used for counting applications because of the energy broadening effect and the absence of a photo peak in their spectra. To overcome their weaknesses, many studies on pseudo spectroscopy have been reported, but most of them have not been able to directly identify the energy of incident gamma rays. In this paper, we propose a method to reconstruct Compton edges in plastic gamma spectra using an artificial neural network for direct pseudo gamma spectroscopy. Spectra simulated using MCNP 6.2 software were used to generate training and validation sets. Our model was trained to reconstruct Compton edges in plastic gamma spectra. In addition, we aimed for our model to be capable of reconstructing Compton edges even for spectra having poor counting statistics by designing a dataset generation procedure. Minimum reconstructible counts for single isotopes were evaluated with metric of mean averaged percentage error as 650 for 60Co, 2000 for 137Cs, 3050 for 22Na, and 3750 for 133Ba. The performance of our model was verified using the simulated spectra measured by a PVT detector. Although our model was trained using simulation data only, it successfully reconstructed Compton edges even in measured gamma spectra with poor counting statistics.

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Validation of energy-weighted algorithm for radiation portal monitor using plastic scintillator

Cited by 20 publications

References 11 publications

Evaluation of Source Identification Method Based on Energy-Weighting Level with Portal Monitoring System Using Plastic Scintillator

Evaluation of Source Identification Method Based on Energy-Weighting Level with Portal Monitoring System Using Plastic Scintillator

Current and Prospective Radiation Detection Systems, Screening Infrastructure and Interpretive Algorithms for the Non-Intrusive Screening of Shipping Container Cargo: A Review

Reconstruction of Compton Edges in Plastic Gamma Spectra Using Deep Autoencoder

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