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The stochastic origin ensembles (SOE) method has been implemented for the reconstruction of neutron and gamma-ray images from a dual-particle imager (DPI). SOE image reconstruction is an iterative stochastic process that creates images using Markov-chain Monte-Carlo sampling with event origins from the reconstructed backprojection cones. This method has been shown to produce image quality comparable...
Proton therapy facilities use high-energy proton beams to destroy cancerous cells with greater specificity than photon-based approaches. However, due to the high energy of these protons, secondary radiation is produced through interactions with the patient and surroundings. These secondary neutrons and photons need to be accurately characterized for the benefit of patients and medical personnel. Experiments...
Correlated neutrons from a Cf-252 spontaneous fission source were measured with a coincidence detection system. The system consisted of three EJ-309 cylindrical liquid scintillators (length and diameter of 7.62 cm) configured to quantify the effects of neutron cross-talk on the total observed correlated counts. Because scatter-based detectors are susceptible to neutron cross-talk, the discrimination...
Neutron sources whose neutrons can be tagged according to their time of emission are extremely useful because time-of-flight spectroscopy can be used to accurately measure their neutron energy spectrum. Sources utilizing the 9Be(α, n)12C reaction exhibit neutron groups corresponding to the states of the 12C residual nucleus. Reactions in which the 12C nucleus is left in an excited state are characterized...
New event-by-event fission models have prompt neutron and gamma-rays that are correlated in time, energy, and multiplicity, however there is limited measurement data available to validate these models. Measurement of high-order fission neutron and gamma-ray coincidences is difficult and there has previously been little motivation to measure properties of both particle types simultaneously. High-order...
A dual-particle imager with sensitivity to both neutrons and photons has been developed for the detection of special nuclear material. This system has the capability to provide spectral information on detected sources that is useful for safeguard applications. In nuclear facilities with high photon background rates, neutron detection can aid in identification and verification capabilities. The dual-particle...
A plutonium metal sample was measured by a fast-neutron multiplicity counter for characterization of spontaneous fission neutron anisotropy and for verification of MCNPX-PoliMi calculations. Accurate neutron angular distribution models are important to properly simulating fast neutron coincidence measurements for nuclear nonproliferation and safeguards applications. A majority of prompt neutrons are...
The separation of neutron and gamma-ray events in organic-liquid scintillators is of significant importance for nonproliferation applications. Typically pulse shape discrimination (PSD) technique is used to differentiate neutron distribution from gamma-ray distribution. However, one of the challenges remains whether the scintillator's PSD is affected with respect to the particle interaction position...
The dual-particle imaging system being developed at the University of Michigan was used at the Joint Research Centre in Ispra, Italy for measurements on samples of special nuclear material. A 1,150-g mixed-oxide (MOX) fuel sample was measured with various shielding configurations to determine how the presence of lead and/or polyethylene shielding degrades the system's ability to localize a source...
Simulations of secondary neutron and gamma-ray production from the 11B(d,n)12C and 27Al(d,n)28Si reactions were conducted using an MCNPX extension called MCUNED. MCUNED enables simulation of deuteron-based nuclear reactions. Deuteron libraries from the TENDL-2010 and TENDL-2011 packages were used. The simulated neutron and gamma-ray spectra were compared to experimental results provided by Taddeucci...
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