Papers by Keyword: Compton Scattering

Abstract: Gamma rays are high energy radiation that can be injurious to individuals who are exposed to them during their work in facilities such nuclear power plants, medical radiotherapy centers and particle accelerator laboratories. Hence radiation shields with adequate attenuation properties are required for protection. In this work gamma ray attenuation problem as given by Beer and Lambert is formulated and coded based on the finite element method for a narrow beam geometry. Attenuation of radiation from radioactive sources, ¹⁷³Cs with energy 0.662 MeV and ⁶⁰ Co having energies 1.173MeV and 1.332MeV in single and multilayer of lead, Tungsten and Ethylene-Propylene Diene Monomer systems have been simulated to study their efficiency in radiation shielding. The simulation results obtained from the finite element code is validated by comparing with well-established Monte Carlo simulation and experimental work. The numerical efficiency of the shielding showed good agreement with the literature.

Abstract: The paper examines the results of theoretical and experimental studies of different interaction of ionizing emission photons with substances, in particular, the photo effect and the Compton scattering of these photons. The paper substantiates a new method of determining the recoil electrons number - the photoelectrons number ratio. The results of certain measurements are presented. The analysis of the results showed that there are noticeable divergences between the theoretical calculations and the experimental data.

Abstract: Abstract. We report the Compton profiles of tantalum chalcogenides (TaS2 and TaSSe) using Hartree–Fock and hybridization of Hartree–Fock and density functional theories within linear combination of atomic (Gaussian) orbitals. To interpret the theoretical data on Compton line shapes, we have measured the Compton profiles using our in-house 100 mCi 241Am γ-ray Compton spectrometer. To understand the relative nature of bonding, we have obtained the equal-valence-electron-density (EVED) profiles. The EVED profiles shows that charge in TaSSe is more localized than TaS2 in the bonding direction which confirms that TaSSe is more covalent than TaS2, which is in agreement with the Mulliken’s population analysis.

Abstract: We report the first ever isotropic experimental Compton profile of tungsten ditelluride using 20 Ci ¹³⁷Cs Compton spectrometer. To compare our experimental data, we have also computed the Compton profiles, energy bands, density of states and band gap using Hartree-Fock and density functional theory within linear combination of atomic orbitals. The measured data is found to be in better accordance with the generalised gradient approximation of density functional theory than Hartree-Fock and local density approximation. We have discussed the nature of bonding in WTe₂ using energy bands and density of states.

Abstract: This work studied the angular distribution of multiple Compton scattering of gamma energy 662 keV, obtained from ¹³⁷Cs source. The gamma rays are incident on carbon scatterer of varying the scattering angles. The phenomenon of multiple Compton scattering has been successfully observed using NaI(Tl) scintillation detector. The energy spectra of the detected photons are observed as a long tail to the single-photon Compton line on the lower side of the full-energy peak in the recorded scattered energy spectrum. The full-energy peak corresponding to singly scattered events is reconstructed analytically and observe that the number of multiply scattered events, having same energy as in the singly scattered distribution.

Abstract: The mass attenuation coefficients and effective atomic numbers of ruby from Vietnam were measured at the different energy of γ-rays using the Compton scattering technique. The compositions of ruby were analyzed by energy dispersive x-rays fluorescence spectrometer and showed the Al₂O₃ is major composition. The results of the experimental values of mass attenuation coefficients and effective atomic numbers showed the good agreement with the theoretical values. The mass attenuation coefficients decreased with the increasing in gamma rays energies, due to the higher photon interaction probability of ruby at lower energy. The effective atomic numbers found to be constant around 10.0 electrons/atom.

Abstract: In the minimum electromagnetism coupling model of interaction between photon and electron, we present a effective and precise calculation on the differential cross section of Compton scattering with the help of the electron renormalized chain propagator. By comparing the result of the differential cross section of the Compton scattering with electron propagator at the tree level and the one loop level, respectively, we find that the correction of the chain diagram is better than the one-loop diagram to the differential cross section in the 10^-3 order.

Abstract: Based on preliminary research results about Compton scattering of saline solution, a linear relationship between the scattered photon counts and the concentrations had been deduced for a certain solution and it had been found that the slope of the lines was decreasing with the atomic number of the cation increasing for LiC1, NaCl and KC1(the same result for MgC1BB2BB and BaC1BB2BB) solution. Now, in order to explain such rule of the slope, the microscopic mechanism of scatterers has been studied. Through the electronic structure of hydrated ions is analyzed in detail: the distance between hydration ion and O atom after optimized, the total energy of hydration ion, the equivalent charge distribution of hydration ion and the electronic density distribution of hydration ion. At last, it is concluded that the reason of the slope decreasing when the atomic number of the alkali cation for KC1, NaCl, LiCl solutions (or MgC1BB2BB and BaClBB2BB solutions) is the bounding strength of the system on its electrons become increasing, the probability of Compton scattering is decreasing, and it will constrain the increasing velocity of the scattered photon counts.

Abstract: We demonstrate what kind of information about the electronic structure one can get from plane projections of electron densities. As an example we use one dimensional (1D) angular correlation of annihilation radiation (ACAR) and Compton scattering spectra for Cd “measured” only for two crystal orientations. Spectra are interpreted in terms of reconstructed 2D densities both in the reduced and extended zone schemes.

Abstract: We present the first ever theoretical and experimental charge Compton profiles of Ni2MnGa Heusler alloy. The measurements have been made using magnetic Compton spectrometer at SPring8, Japan. The Compton profiles and energy bands have been computed using Hartree-Fock, density functional theory with local density and generalized gradient approximations. It is seen that the Hartree-Fock based Compton profile is relatively in better agreement with the experimental profiles. In addition, we also report the energy bands, density of states and valence charge densities using full potential linearized augmented plane-wave method.