High-order angular correlation of californium-252 fission neutrons and the effect of detector cross-talk

Joyce, Malcolm J.; Sarwar, Rashed; Astromskas, Vytautas; Chebboubi, A.; Croft, Stephen; Litaize, O.; Vogt, R.; Zimmerman, C.H.

doi:10.1016/j.nima.2019.01.092

Cited by 4 publications

(1 citation statement)

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“…However, plastic scintillators are strongly sensitive to gamma rays, which, in addition, may scatter between detectors and thus produce parasitic coincidences that will be merged with useful (i.e., different-particle) coincidence events expected from fission. For instance, (α,n) reactions accompanied by correlated gamma rays, or pure gamma ray sources emitting correlated gamma radiations can induce undesired high-order coincidences [6] due to the mentioned multi-detector hit events by a single gamma-ray or neutron, that are currently under worldwide investigations [4], [7][8][9][10]. Although some plastic scintillators allow via the Pulse Shape Discrimination (PSD) to sort neutron and gamma ray events [11][12][13][14], they are not a practical alternative for radioactive waste drum characterization.…”

Section: Introductionmentioning

confidence: 99%

Sorting fission from parasitic coincidences of neutrons and gamma rays in plastic scintillators using particle times of flight

et al. 2021

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This work addresses the use of plastic scintillators as an alternative to 3He detectors for radioactive waste drum characterization. The time response of scintillators is three orders of magnitude faster than that of gas proportional counters and they offer similar neutron detection efficiency at lower cost. However, they are sensitive to gamma rays and the commonly used Pulse Shape Discrimination technique is not possible with basic PVT scintillators. This paper reports on an innovative data processing technique allowing to extract spontaneous fission events from parasitic coincidences, such as those from the (α,n) reactions accompanied by correlated gamma rays or from pure gamma-ray sources emitting correlated radiations. The proposed approach makes advantage of differences in the pulse detection times recorded in measurements with the 252Cf, AmBe and 60Co sources. More precisely, a 2D histogram of time delays between the detected 2nd and 1st pulses, on the x-axis, and between the 3rd and 2nd pulses, on the y-axis, is found to allow for selection of a region of interest most relevant to spontaneous fission events.

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