Evaluation of Highly Enriched Uranium (HEU) surrogate sources for use in training and modeling

Scholz, Z.; Millett, Marshall; Schell, M.

doi:10.1016/j.nima.2018.09.056

Cited by 1 publication

(2 citation statements)

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“…To mitigate this issue a more realistic signature can be made using the addition of another radionuclide to the neutron source. The chosen enhancement depends somewhat on the target material, with 57 Co often used where highly enriched uranium (HEU) is of concern [48], but for 239 Pu this role is performed by 133 Ba [49], and this work has demonstrated that similar FoM results can be obtained from such a combination proxy source. The introduction of the 133 Ba into the spectrum has the effect of reducing the n-γ ratio from that of pure AmBe, to a closer approximation of SNM (in our case the respective activities more closely aligned to the dual shielded 5 cm Pb/HDPE measurement).…”

Section: Discussionmentioning

confidence: 97%

“…Further enhancement could be provided by considering narrower energy regimes, and providing a proxy source at each point. This has been tested by other groups [48,49], although with the plastic scintillator tested here, the low resolution prevents spectroscopic information being discernable. The further addition of 241 Am, 109 Cd, and 137 Cs was shown to provide a good replication of plutonium spectra [49].…”

Section: Discussionmentioning

confidence: 99%

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Assessing the suitability of three proxy sources for the development of detectors of special nuclear materials

et al. 2020

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Numerous techniques and equipment have been developed to provide a capability for the detection of special nuclear materials (SNM), but due to the necessary security measures surrounding these materials alternate, or proxy, neutron sources are often utilised in their stead. In this paper we report the neutron and gamma pulse shape discrimination response of plastic scintillator to mixed neutron/gamma beams produced from two radionuclide neutron sources, and also from an SNM source of weapons-grade plutonium. We discuss the suitability of using radionuclide sources, with appropriate shielding configurations as proxy sources for SNM. A 3σnth-γ discrimination level has been achieved for an SNM source at a low-level energy threshold of ∼220 keVee when a shielding configuration of 5 cm of lead was implemented. Varying amounts of lead and high-density polyethylene (HDPE) shielding were also investigated with the 3σ limit being reached by ∼240 keVee. This work shows that an AmBe neutron source serves as an appropriate SNM proxy achieving a comparable value for figure of merit above ∼1 MeVee. For energies below 1 MeVee down to ∼100 keVee a closer approximation of the expected FoM for SNM can be attained when using 252Cf as a proxy source or by utilising an ‘enhanced’ AmBe source with the addition of a further low energy γ ray source.

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Section: Discussionmentioning

confidence: 97%