Evaluation of neutron light output response functions in EJ-309 organic scintillators

Norsworthy, Mark A.; Poitrasson-Rivière, Alexis; Ruch, Marc L.; Clarke, Shaun D.; Pozzi, Sara A.

doi:10.1016/j.nima.2016.10.035

Cited by 40 publications

(20 citation statements)

References 25 publications

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“…As both the magnitude of the scintillation intensity and the quenching factor are properties of the scintillating medium, the proton light yield is a characteristic unique to each scintillator material formulation. Existing physics-based models of proton light yield give an unreliable extrapolation to recoil energies below 1 MeV [8] and it is in this low energy region where the prompt fission neutron spectrum of special nuclear material peaks. Eljen Technology's EJ-200, EJ-204, and EJ-208 scintillators are potential candidates for the SVSC due to their fast rise times and relatively long (> 1.5 m) optical attenuation lengths.…”

Section: Motivationmentioning

confidence: 99%

Low energy light yield of fast plastic scintillators

Laplace

Goldblum

Brown

et al. 2020

Nuclear Instruments and Methods in Physics Research Section A:

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Compact neutron imagers using double-scatter kinematic reconstruction are being designed for localization and characterization of special nuclear material. These neutron imaging systems rely on scintillators with a rapid prompt temporal response as the detection medium. As n-p elastic scattering is the primary mechanism for light generation by fast neutron interactions in organic scintillators, proton light yield data are needed for accurate assessment of scintillator performance. The proton light yield of a series of commercial fast plastic organic scintillators-EJ-200, EJ-204, and EJ-208-was measured via a double time-of-flight technique at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. Using a tunable deuteron breakup neutron source, target scintillators housed in a dual photomultiplier tube configuration, and an array of pulse-shape-discriminating observation scintillators, the fast plastic scintillator light yield was measured over a broad and continuous energy range down to proton recoil energies of approximately 50 keV. This work provides key input to event reconstruction algorithms required for utilization of these materials in emerging neutron imaging modalities.

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Section: Motivationmentioning

confidence: 99%

Low energy light yield of fast plastic scintillators

Laplace

Goldblum

Brown

et al. 2020

Nuclear Instruments and Methods in Physics Research Section A:

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“…7. The Birks model, a semi-empirical relationship described by Norsworthy et al [50], was implemented in the detector response code to convert neutron energy deposited on protons to light output in the EJ-309 scintillator. The light output response from photon scattering on electrons was one-to-one.…”

Section: Simulationmentioning

confidence: 99%

“…8(b) and 9(b), better quantify the agreement. In the neutron pulse height histogram, disagreement above 0.8 MeV is attributed to error in the function to convert proton recoil energy to light output used in the detector response emulator[50]. For photon pulse heights below 0.8 MeV, the simulation underpredicts the count rate.…”

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confidence: 99%

Measured and simulated Cf(sf)252 prompt neutron-photon competition

et al. 2018

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Neutrons and photons are characteristically emitted during the nuclear fission process when a deformed, neutron-rich nucleus divides into two fragments that then de-excite. During de-excitation, neutrons are emitted first, followed by photons; this process gives rise to correlated emissions. Few data exist on event-by-event neutron-photon correlation. In this work, 252 Cf(sf) neutron and photon correlations were measured with an array of 45 liquid organic scintillation detectors and a fission chamber. The measured correlations are compared with MCNPX − PoliMi simulations using the built-in model and two event-by-event fission models, CGMF and FREYA, which predict correlations in prompt emissions from fission. Experimental results suggest weak neutron-photon competition during fragment de-excitation.

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“…where dE/dx is the proton stopping power in stilbene [23]. The fitted parameters of a and b were found to be 1.63 (MeVee/MeV) and 27.83 (mg/(cm 2 MeV)), respectively.…”

Section: Calibrationsmentioning

confidence: 95%

Characterizing subcritical assemblies with time of flight fixed by energy estimation distributions

Monterial¹,

Marleau²,

Pozzi³

2018

Nuclear Instruments and Methods in Physics Research Section A:

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We present the Time of Flight Fixed by Energy Estimation (TOFFEE) as a measure of the fission chain dynamics in subcritical assemblies. TOFFEE is the time between correlated gamma rays and neutrons, subtracted by the estimated travel time of the incident neutron from its proton recoil. The measured subcritical assembly was the BeRP ball, a 4.482 kg sphere of α-phase weapons grade plutonium metal, which came in five configurations: bare, 0.5, 1, and 1.5 in iron, and 1 in nickel closed fitting shell reflectors. We extend the measurement with MCNPX-PoliMi simulations of shells ranging up to 6 inches in thickness, and two new reflector materials: aluminum and tungsten. We also simulated the BeRP ball with different masses ranging from 1 to 8 kg. A two-region and single-region point kinetics models were used to model the behavior of the positive side of the TOFFEE distribution from 0 to 100 ns. The single region model of the bare cases gave positive linear correlations between estimated and expected neutron decay constants and leakage multiplications. The two-region model provided a way to estimate neutron multiplication for the reflected cases, which correlated positively with expected multiplication, but the nature of the correlation (sub or super linear) changed between material types. Finally, we found that the areal density of the reflector shells had a linear correlation with the integral of the two-region model fit. Therefore, we expect that with knowledge of reflector composition, one could determine the shell thickness, or vice versa. Furthermore, up to a certain amount and thickness of the reflector, the two-region model provides a way of distinguishing bare and reflected plutonium assemblies.Research and development is generally geared towards accounting for the differences in thermal capture He-3based systems and FNMCs [9]. As a result, the development of new measurement systems is underpinned by more or less the same multiplicity analysis developed over three decades ago. Therefore, data analysis using new measurement systems continue to require both high efficiency and accurate knowledge of the efficiency of the system. This creates A design principle that drives systems toward larger sizes and geometries that limit applications and portability. However, portability is often a feature demanded by field applications such as treaty verification and nuclear emergency response.Instead of optimizing fast organic scintillator-based systems to the design principles of multiplicity counting, we have leveraged a few key additional signatures available to these detectors while investigating new analysis methodologies:1. Prompt gamma rays released from fission, which are distinguished from neutrons with pulse shape discrimination (PSD) [10] [11] 2. Energy imparted by incident neutrons measured through proton recoil. 3. Timing between these detected events, measured with arXiv:1801.08126v1 [physics.data-an]

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Evaluation of neutron light output response functions in EJ-309 organic scintillators

Cited by 40 publications

References 25 publications

Low energy light yield of fast plastic scintillators

Low energy light yield of fast plastic scintillators

Measured and simulated Cf(sf)252 prompt neutron-photon competition

Characterizing subcritical assemblies with time of flight fixed by energy estimation distributions

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