: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Phy-X / PSD: Development of a user friendly online software for calculation of parameters relevant to radiation shielding and dosimetry

Calculation of radiation attenuation coefficients for shielding concretes

The shielding of γ-rays by concrete has been investigated for concretes containing different amounts of barite and normal weight aggregates. The linear attenuation coefficients ( μ , cm −1 ) have been calculated at photon energies of 1 keV to 100 GeV using XCOM and the obtained results compared with the measurements at the photon energies of 0.66 MeV and 1.33 MeV. It is shown that the type of the aggregate is more important than the amount of aggregate used in concrete for γ-ray shielding.

Radiation shielding of concretes containing different aggregates

Photon attenuation coefficients of concrete includes barite in different rate

Investigation of hematite-serpentine and ilmenite-limonite concretes for reactor radiation shielding

On the utilization of heavy concrete for radiation shielding

This paper is concerned with the study of the leakage spectra of total gamma rays and fast neutrons from two types of heavy concretes made from local magnetite ores. The two types are the steel-magnetite concrete (ρ=5.11 g/cm3) and the basalt-magnetite concrete (ρ=3.05 g/cm3). The radiation source used was a collimated beam emitted from one of the horizontal channels of the ET-RR-1 reactor. Total gamma rays and fast neutrons were measured using a gamma-neutron spectrometer with a stilbene scintillator. Gamma ray or neutron events were rejected by a pulse shape discriminator based on the zero cross over method. The obtained data were displayed in the form of spatial fluxes and energy distributions and attenuation curves. The linear attenuation coefficients for total gamma rays, macroscopic removal cross sections for fast neutrons and half-value layers for gamma rays and neutrons have been obtained for the whole energy range and at different energies. Comparison with other published data has been done when such data are available. For comparison, the steel-magnetite concrete is a much better radiation attenuator than the magnetite and basalt-magnetite concretes, especially for thick shields.

https://iopscience.iop.org/article/10.1143/JJAP.36.3692/pdf

Ibrahim Bashter

Papers

Calculation of radiation attenuation coefficients for shielding concretes

Investigation of hematite-serpentine and ilmenite-limonite concretes for reactor radiation shielding

On the utilization of heavy concrete for radiation shielding

Magnetite ores with steel or basalt for concrete radiation shielding

A comparative study of the attenuation of reactor thermal neutrons in different types of concrete