Neutron Production, Neutron Facilities and Neutron Instrumentation

Vogel, Sven C.; Priesmeyer, H.G.

doi:10.2138/rmg.2006.63.2

Cited by 25 publications

(11 citation statements)

References 66 publications

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“…Two neutron diffraction experiments have been conducted with the High Pressure-Preferred Orientation (HIPPO) [28] [29] diffractometer at the Los Alamos Neutron Science Center (LANSCE) [30][31]. The instrument is described in detail in the aforementioned references and Despite great efforts for beam collimation, spurious peaks originating from the furnace and not the sample were observed.…”

Section: Neutron Diffractionmentioning

confidence: 99%

In situ synthesis and characterization of uranium carbide using high temperature neutron diffraction

Reiche

Vogel

Tang

2016

Journal of Nuclear Materials

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We investigated the formation of UCx from UO2+x and graphite in situ using neutron diffraction at high temperatures with particular focus on resolving the conflicting reports on the crystal structure of non-quenchable cubic UC2. The agents were UO2 nanopowder, which closely imitates nano grains observed in spent reactor fuels, and graphite powder. In situ neutron diffraction revealed the onset of the UO2 + 2C  UC + CO2 reaction at 1440˚C, with its completion at 1500˚C. Upon further heating, carbon diffuses into the uranium carbide forming C2 groups at the octahedral sites. This resulting high temperature cubic UC2 phase is similar to the NaCl-type structure as proposed by Bowman et al. Our novel experimental data provide insights into the mechanism and kinetics of formation of UC as well as characteristics of the high

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Section: Neutron Diffractionmentioning

confidence: 99%

In situ synthesis and characterization of uranium carbide using high temperature neutron diffraction

Reiche

Vogel

Tang

2016

Journal of Nuclear Materials

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“…The disagreement in the reported data was part of the motivation for the researchp erformedh erein, where powder and pressed pellets of neat TATB were measured at the at the Los Alamos Neutron Science Center's (LANSCE) Lujan Center spallation neutron source [17] using the High Pressure Preferred Orientation (HIPPO) diffractometer [18]. Neutron diffraction was chosen for several reasons despite its lowerf lux or lowerr esolutionc ompared to X-rays [19].…”

mentioning

confidence: 99%

Neutron Diffraction Measurements and Micromechanical Modelling of Temperature‐Dependent Variations in TATB Lattice Parameters

Yeager

Luscher

Vogel

et al. 2016

Propellants Explo Pyrotec

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[c] 1IntroductionTriaminotrinitrobenzene (TATB) is ah igh explosive thati s used in extremely safe ("insensitive") explosive formulations. Twoo ft he most widely used formulationsa re the plastic-bonded explosives( PBX) PBX 9502 (95 wt-% TATB, 5wt-% Kel-F8 00 polymer binder) and LX-17 (92.5 wt-% TATB, 7.5 wt-% Kel-F8 00). The propensity of these PBX formulationst or emain unreactiveu nder aw ide rangeo fp otential insults, including fragment impact and fire disaster scenarios, has led to their widespread applicationa cross many weapons systems [1].W hile TATB is advantageous in this regard, there are three sources of anisotropy in TATB crystals that complicate mechanisms of polycrystalr esponse. First,T ATBh as at riclinic crystal structure that is as ource of crystal anisotropy in its own right [2].S econd, each triclinicu nit cell of TATB possesses two TATB molecules each comprising am odified benzene ring.T he bonds within the modified benzene ring are sufficiently strong that the molecules remain flat and aligned in layersa long the (001)c rystallographic plane. The intermolecularb onds formed within these molecular layers of TATB are strong hydrogen bonds, while the bonds betweena djacent layers are of relatively weaker van der Waals type, leading to stronglya nisotropic deformation and thermal expansion behavior. Third, the geometric morphology of TATB crystals is also anisotropic;d epending on the synthesis route, the graphite-like platelet aspect ratioc an be somewhat mitigated or exaggerated, wheret he large flat surfacesc orrespond to crystallographic (001) planes [3,4].The thermal expansion of single-crystal TATB is entirely reversible. However,b ulk polycrystalline TATB exhibits an irreversible volumee xpansion upon thermal cycling while in Abstract:T riaminotrinitrobenzene (TATB) is ah ighly anisotropic molecular crystal used in several plastic-bonded explosive (PBX) formulations. TATB-based explosives exhibit irreversible volume expansion( "ratchet growth") whent hermally cycled. At heoretical understanding of the relationship betweena nisotropy of the crystal, crystal orientation distribution (texture) of polycrystalline aggregates, and the intergranular interactions leading to this irreversible growth is necessary to accurately develop physics-based predictive models for TATB-basedPBXs under variousthermal environments. In this work, TATB lattice parameters were measured using neutron diffraction duringt hermal cyclingo fl oose powder and ap ressedp ellet. The measured lattice parameters help clarify conflictingr eports in the literature as these new results are more consistent with one set of previous results than another.T he lattice parameters of pressed TATB were also measured as af unction of temperature, showings ome differences from the powder.T his data is used along with anisotropic single-crystal stiffness moduli reported in thel iterature to model the nominal stresses associated with intergranularc onstraints during thermal expansion. The texture of both specimens were characterized...

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“…referred to literature overviews by Bacon (1975), Bée (1988), and Vogel and Priesmeyer (2006) for further technical details on the methods of recording the energy and momentum transfers.…”

Section: Neutron Scatteringmentioning

confidence: 99%

Structure and Dynamics of Confined C-O-H Fluids Relevant to the Subsurface: Application of Magnetic Resonance, Neutron Scattering, and Molecular Dynamics Simulations

Gautam

Cole

2017

Front. Earth Sci.

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Neutron Production, Neutron Facilities and Neutron Instrumentation

Cited by 25 publications

References 66 publications

In situ synthesis and characterization of uranium carbide using high temperature neutron diffraction

In situ synthesis and characterization of uranium carbide using high temperature neutron diffraction

Neutron Diffraction Measurements and Micromechanical Modelling of Temperature‐Dependent Variations in TATB Lattice Parameters

Structure and Dynamics of Confined C-O-H Fluids Relevant to the Subsurface: Application of Magnetic Resonance, Neutron Scattering, and Molecular Dynamics Simulations

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