Thermal Neutron Measurements Inside an Aircraft for SEE Assessment

Weulersse, C.; Mazurek, M.; Pinas, C. Delcher; Mills, Richard; Guerard, B.

doi:10.1109/tns.2023.3256095

Cited by 1 publication

(1 citation statement)

References 21 publications

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“…It is also worth noting that the hydrogen NKE of pure light water across melting, presented here, is more similar in value to that of seawater at high pressure than to that of room-temperature water at ambient pressure. 50 These findings are relevant in the context of neutron transport modeling of the thermal scattering law in applications ranging from environmental field-scale soil moisture analysis for the quantification of biomass and snow 51,52 to investigations of neutron albedo in space weather ground-level and altitude observations, 53,54 where water hydrogen in soil, air, liquid water, and snow determines the amount of ground albedo neutrons in the sensitive energy ranges.…”

Section: Resultsmentioning

confidence: 99%

Quantum motion of oxygen and hydrogen in water: Atomic and total kinetic energy across melting from neutron scattering measurements

Romanelli,

Andreani,

Bocedi

et al. 2024

The Journal of Chemical Physics

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We provide a concurrent measurement of the hydrogen and oxygen nuclear kinetic energies in the water molecule across melting at 270 K in the solid phase and 276 K in the liquid phase. Experimental values are obtained by analyzing the neutron Compton profiles of each atomic species in a deep inelastic neutron scattering experiment. The concurrent measurement of the atom kinetic energy of both hydrogen and oxygen allows the estimate of the total kinetic energy per molecule due to the motion of nuclei, specifically 35.3 ± 0.8 and 34.8 ± 0.8 kJ/mol for the solid and liquid phases, respectively. Such a small difference supports results from ab initio simulations and phenomenological models from the literature on the mechanism of competing quantum effects across the phase change. Despite the experimental uncertainties, the results are consistent with the trend from state-of-the-art computer simulations, whereby the atom and molecule kinetic energies in the liquid phase would be slightly lower than in the solid phase. Moreover, the small change of nuclear kinetic energy across melting can be used to simplify the calculation of neutron-related environmental dose in complex locations, such as high altitude or polar neutron radiation research stations where liquid water and ice are both present: for neutron energies between hundreds of meV and tens of keV, the total scattering cross section per molecule in the two phases can be considered the same, with the macroscopic cross section only depending upon the density changes of water near the melting point.

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