C. Trivelpiece
Pennsylvania State University
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Featured researches published by C. Trivelpiece.
IEEE Transactions on Nuclear Science | 2016
J. Nattress; M. Mayer; Albert Foster; A. Barhoumi Meddeb; C. Trivelpiece; Zoubeida Ounaies; Igor Jovanovic
We report on the measurements of monoenergetic neutrons from DD and DT fusion reactions by use of the capture gating method in a heterogeneous plastic-glass composite scintillation detector. The cylindrical detector is 5.08 cm in diameter and 5.05 cm in height and was fabricated using 1-mm diameter Li-doped glass rods (GS20) and scintillating polyvinyl toluene (EJ-290). Different scintillation decay constants are used to identify energy depositions in two materials constituting the composite scintillator. Geant4 simulations of the neutron thermalization and capture process were conducted, finding a mean capture time of approximately 2.6 μs for both DD and DT neutrons. A capture gating time acceptance window based on simulation results was used to identify the neutron thermalization pulses. The total scintillation light yield produced in neutron thermalization was measured and found to show consistency on event-by-event basis despite the variety of neutron thermalization histories prior to capture. The ratio of light yields from thermalization of 14.1 MeV and 2.45 MeV neutrons in the EJ-290 scintillator was determined to be 14.6, and the light output from 2.45 MeV neutrons was also correlated to its electron equivalent, obtaining a value of 0.58±0.05 MeVee.
Archive | 2017
C. Trivelpiece; Jarret A. Rice; Carlo G. Pantano
The dissolution of glass in aqueous solution is thermodynamically driven by the non-equilibrium state of the glass itself. Under conditions of high alkalinity, the solution of glass can be highly concentrated, and near-equilibrium with respect to crystalline mineral phases. For durable glasses, the transformation of a glass into its equilibrium crystalline phases is usually kinetically limited by nucleation effects, surface alteration layers on the glass, and concentration of the solution. But in some cases, the precipitation of secondary phases can occur to drive the continued dissolution of the glass. In this study, the transformation of two simple and soluble alkali silicate glasses, Li-disilicate and Na-disilicate (LDS and NDS), was followed with solution analysis, x-ray diffraction and thermodynamic modeling using Geochemist’s Work Bench (GWB). The evolution of the concentrated glass solution, as opposed to the kinetics of dissolution, was the primary focus. It is shown that the LDS system undergoes significant supersaturation followed by precipitation of hydrated Li-disilicate crystals; this was in reasonable agreement with the GWB modeling, although the GWB outputs found the solution saturated with respect to other crystalline phases which were not observed. For the NDS system, precipitation was much less prevalent even though more than 75% of the glass was in solution. In contrast to the LDS system, the NDS system did not precipitate any of the simple binary Na-silicates, but rather formed a gel which persisted for up to 5000 hrs. The saturation indices for zeolitic phases were exceedingly high, and with the trace amounts of Al in these solutions, the crystallization of zeolite Na-P1 was observed by x-ray diffraction after 1000 hrs. These observations are relevant to the long-term stability of complex, multicomponent nuclear waste glasses.
International Journal of Modern Physics: Conference Series | 2016
Igor Jovanovic; Albert Foster; V. Kukharev; M. Mayer; Amira Barhoumi Meddeb; J. Nattress; Zoubeida Ounaies; C. Trivelpiece
Shielded special nuclear material (SNM), especially highly enriched uranium, is exceptionally difficult to detect without the use of active interrogation (AI). We are investigating the potential use of low-dose active interrogation to realize simultaneous high-contrast imaging and photofission of SNM using energetic gamma-rays produced by low-energy nuclear reactions, such as 11B(d,nγ)12C and 12C(p,p′)12C. Neutrons produced via fission are one reliable signature of the presence of SNM and are usually identified by their unique timing characteristics, such as the delayed neutron die-away. Fast neutron spectroscopy may provide additional useful discriminating characteristics for SNM detection. Spectroscopic measurements can be conducted by recoil-based or thermalization and capture-gated detectors; the latter may offer unique advantages since they facilitate low-statistics and event-by-event neutron energy measurements without spectrum unfolding. We describe the results of the development and characterization of a new type of capture-gated spectroscopic neutron detector based on a composite of scintillating polyvinyltoluene and lithium-doped scintillating glass in the form of millimeter-thick rods. The detector achieves >108 neutron–gamma discrimination resulting from its geometric properties and material selection. The design facilitates simultaneous pulse shape and pulse height discrimination, despite the fact that no materials intrinsically capable of pulse shape discrimination have been used to construct the detector. Accurate single-event measurements of neutron energy may be possible even when the energy is relatively low, such as with delayed fission neutrons. Simulation and preliminary measurements using the new composite detector are described, including those conducted using radioisotope sources and the low-dose active interrogation system based on low-energy nuclear reactions.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2015
M. Mayer; J. Nattress; V. Kukharev; Albert Foster; Amira Barhoumi Meddeb; C. Trivelpiece; Zoubeida Ounaies; Igor Jovanovic
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2015
M. Mayer; J. Nattress; C. Trivelpiece; Igor Jovanovic
International Journal of Applied Glass Science | 2012
C. Trivelpiece; John J. Petrunis; Carlo G. Pantano; R. Gregory Downing
Proceedings of SPIE | 2010
C. Trivelpiece; Jack S. Brenizer; Carlo G. Pantano
Bulletin of the American Physical Society | 2015
M. Mayer; J. Nattress; Amira Barhoumi Meddeb; Albert Foster; C. Trivelpiece; Paul Rose; Anna Erickson; Zoubeida Ounaies; Igor Jovanovic
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2014
Edward Cazalas; C. Trivelpiece; Igor Jovanovic
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 2011
C. Trivelpiece; Jack S. Brenizer