Atomic scale Monte-Carlo simulations of neutron diffraction experiments on stoichiometric uranium dioxide up to 1664 K

Xu, Shuqi; Noguère, G.; Desgranges, Lionel; Damián, José Ignacio Márquez

doi:10.1016/j.nima.2021.165251

Cited by 5 publications

(4 citation statements)

References 30 publications

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“…In our work, we investigate the magnetic effects through Monte-Carlo simulations. Similar to the process developed for simulating neutron diffraction measurements on uranium dioxide [216], the calculation scheme is composed of MD and DFT calculations, Monte-Carlo simulations, and experimental correction.…”

Section: Magnetic Scattering Pluginmentioning

confidence: 99%

HighNESS conceptual design report: Volume I

Santoro,

Abou El Kheir,

Acharya

et al. 2024

JNR

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The European Spallation Source, currently under construction in Lund, Sweden, is a multidisciplinary international laboratory. Once completed to full specifications, it will operate the world’s most powerful pulsed neutron source. Supported by a 3 million Euro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNESS) has been completed to develop a second neutron source located below the spallation target. Compared to the first source, designed for high cold and thermal brightness, the new source has been optimized to deliver higher intensity, and a shift to longer wavelengths in the spectral regions of cold (CN, 2–20 Å), very cold (VCN, 10–120 Å), and ultracold (UCN, >500 Å) neutrons. The second source comprises a large liquid deuterium moderator designed to produce CN and support secondary VCN and UCN sources. Various options have been explored in the proposed designs, aiming for world-leading performance in neutronics. These designs will enable the development of several new instrument concepts and facilitate the implementation of a high-sensitivity neutron-antineutron oscillation experiment (NNBAR). This document serves as the Conceptual Design Report for the HighNESS project, representing its final deliverable.

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Section: Magnetic Scattering Pluginmentioning

confidence: 99%

HighNESS conceptual design report: Volume I

Santoro,

Abou El Kheir,

Acharya

et al. 2024

JNR

Self Cite

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“…The measurements were performed on the time-of-flight spectrometer IN6 [57] at ILL, with detailed description available in [18,19]. In this work, similar to the process developed for simulating neutron diffraction measurements on uranium dioxide [58], the calculation scheme depicted in figure 10 consists of atomistic simulations as previously presented in section 3, Monte Carlo simulations, and non-linear least squares fits to include instrument properties not accounted for in the simulations and determine both central value and HWHM of the zero-field splitting. The last two steps are detailed as follows.…”

Section: Calculation Schemementioning

confidence: 99%

Physical model of neutron scattering by clathrate hydrate and C 60 hosting paramagnetic oxygen molecules

Xu (许树琪),

DiJulio,

Marquez Damian

et al. 2024

J. Phys.: Condens. Matter

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This paper describes the physical modelling of neutron scattering in two polycrystalline inclusion compounds, fully deuterated clathrate hydrate and C 60 , each with paramagnetic oxygen as guest molecules. For studying the suitability of these materials for neutron moderation to very low energies, the model includes, in addition to the magnetic neutron scattering by the oxygen, the nuclear scattering by all constituents. The theoretical total cross sections are calculated based on the phonon density of states obtained by density functional theory and molecular dynamics simulations. At low temperatures, the developed scattering kernels are in good agreement with experimental neutron scattering data reported in the literature. At 20 K and above, a Lorentzian distribution for the zero-field splitting of the magnetic substates of the spin triplet of the oxygen molecules helps to reproduce magnetic peaks observed in inelastic neutron scattering experiments better than the original theory based on a single-valued splitting constant. Neutron spectra obtained by Monte Carlo simulations in infinite media are presented, highlighting the potential use of O 2 -containing fully deuterated clathrate hydrate as a neutron moderator for the production of very cold neutrons.

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“…However, the impact on the coherent elastic cross section σ el coh (E) increases with the incident neutron energy E until σ el coh (E) reaches the asymptotic part (when E is larger than about 0.1 eV). The impact of c O 123 on the Monte-Carlo simulations of uranium dioxide is discussed in reference [53].…”

Section: Anharmonicity Of Oxygenmentioning

confidence: 99%

Generation of thermal scattering files with the CINEL code

Noguère

2022

EPJ Nuclear Sci. Technol.

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The CINEL code dedicated to generate the thermal neutron scattering files in ENDF-6 format for solid crystalline, free gas materials and liquid water is presented. Compared to the LEAPR module of the NJOY code, CINEL is able to calculate the coherent and incoherent elastic scattering cross sections for any solid crystalline materials. Specific material properties such as anharmonicity and texture can be taken into account in CINEL. The calculation of the thermal scattering laws can be accelerated by using graphics processing unit (GPU), which enables to remove the short collision time approximation for large values of momentum transfer. CINEL is able to generate automatically the grids of dimensionless momentum and energy transfers. The Sampling the Velocity of the Target nucleus (SVT) algorithm capable of determining the scattered neutron distributions is implemented in CINEL. The obtained distributions for free target nuclei such as hydrogen and oxygen are in good agreement with analytical results and Monte-Carlo simulations when incident neutron energies are above a few eV. The introduction of the effective temperature and the rejection step to the SVT algorithm shows improvements to the neutron up-scattering treatment of hydrogen bound in liquid water.

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Atomic scale Monte-Carlo simulations of neutron diffraction experiments on stoichiometric uranium dioxide up to 1664 K

Cited by 5 publications

References 30 publications

HighNESS conceptual design report: Volume I

HighNESS conceptual design report: Volume I

Physical model of neutron scattering by clathrate hydrate and C 60 hosting paramagnetic oxygen molecules

Generation of thermal scattering files with the CINEL code

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