Neutron detection with large plastic scintillators for RPM applications

Abstract

Homeland security requests the use Radiation Portal Monitor (RPM) to detect and differentiate gamma and neutron radiation. Gamma detection is required for illicit transportation of radioactive matter detection. Neutron detection is important to control nonproliferation of enriched material. Manufacturers worldwide propose sensors based on 3 He which give the actual state of art in term of neutron detection. The price fluctuations due to the announcement of the shortage of 3 He forces manufacturers to find viable alternative. From 10 years sensors providers have the challenge to replace previous 3 He detectors that are known to be the most commonly deployed neutron sensor. As 3 He detectors can only detect neutron, they must be completed with gamma detector. The proposed approach is based on pulse time correlation between adjacent sensors from signal collected by EJ200 plastic scintillators to detect gamma and neutron. Results obtained during FP7 Scintilla project test campaigns show the system relevance for replacement of today's 3 He detectors.

High-Resolution Gamma Spectrometry of a Plutonium Bearing Waste Drum With High-Energy Reaction-Induced Gamma Rays

“…The shorter the excited state lifetime, the larger the broadening effect, as can be seen with the 3853-keV gamma ray, for which the de-excitation of the 3853.807-keV level (half-life of 8.60 ps) induces a smaller broadening. The 3089-keV gamma ray corresponding to the transition from the first excited state of 13 C to the ground state was also expected but is not identifiable in Fig. 4, probably due to an expected large Doppler broadening (1.07-fs lifetime of the first excited level).…”

“…The following list, in the order of increasing atomic number of the target nuclei or excited reaction daughters (e.g., 13 C, 22 Na, and 26 Mg), reports capture gamma rays and gamma transitions of (α, x) and (n, n ) reaction products that possibly correspond to gamma rays observed in the spectrum.…”

“…Indeed, large detection solid angles and volumes are needed to preserve coincidence counting statistics and therefore, a large number of PSD scintillators should be implemented as their size is limited. Actually, the difference between neutron and gamma-ray pulse tails is not preserved in large PSD scintillators due to multiple light scattering [12], [13]. Finally, a large array of small (maximum 5 in) PSD scintillators would increase the cost to a similar level as 3 He detectors.…”

Novel epoxy-bPBD-BisMSB composite plastic scintillator for alpha, beta and gamma radiation detection

“…A scintillation detector is realized by coupling it to a photo-detector that produces electrical pulses on absorption of these light pulses, which can be processed and correlated with incident radiation intensity and energy 1 . Scintillation detectors have various applications such as radiation spectrometry 2 , medical imaging, positron emission tomography(PET) 3 , Industrial radiography 4 , high energy physics experiments 5 , radioisotope identification 6 , homeland security 7 and nuclear & radiological emergency management 8 . Scintillators are broadly categorized in two types (i) Inorganic scintillators and Organic scintillators.…”

Study of gamma-ray background noise for radioactive waste drum characterization with plastic scintillators

“…Indeed, large detection volumes are needed to preserve coincidence counting statistics and therefore, a large number of PSD scintillators should be implemented as their size is limited. Actually, the difference between neutron and gamma ray pulse tails is not preserved in large PSD scintillators due to light multiple scattering [5] [6]. Finally, a large array of small (maximum 5 inches) PSD scintillators would increase the cost to a similar level as 3 He detectors, not to mention flammability and toxicity of organic liquid scintillators.…”