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The present work reports the theoretical investigation of the scattering of electrons and positrons by the ethane (C 2 H 6 ) molecule over the energy range 1 eV–1 MeV. The investigation was carried out by taking into account the screening correction arising from a semiclassical analysis of the atomic geometrical overlapping of the scattering observables calculated in the independent atom approximation. The study is presented through the calculations of a broad spectrum of observable quantities, namely differential, integrated elastic, momentum transfer, viscosity, inelastic, grand total, and total ionization cross-sections and the Sherman functions. A comparative study was carried out between scattering observables for electron impact with those for positron impact to exhibit the similarity and dissimilarity arising out of the difference of the collisions of impinging projectiles with the target. Partial-wave decomposition of the scattering states within the Dirac relativistic framework employing a free-atom complex optical model potential was used to calculate the corresponding observable quantities of the constituent atoms. The results, calculated using our recipe, were compared with the experimental and theoretical works available in the literature. The Sherman function for a e ± – C 2 H 6 scattering system is presented for the first time in the literature. The addition of the screening correction to the independent atom approximation method was found to substantially reduce the scattering cross-sections, particularly at forward angles for lower incident energies. [ABSTRACT FROM AUTHOR]

This article incorporates details of our calculations of the observable quantities for the scattering of electrons and positrons from a post transition metal Thallium (Tl), in the energy range of 1 eV ≤ E i ≤ 1 MeV, using the relativistic Dirac partial wave (phase-shift) analysis employing a complex optical-potential. Absolute differential, integrated elastic and inelastic, transport, total ionization, and total cross sections and a thorough study of the critical minima in the elastic differential cross sections along with the associated angular positions of the maximum polarization points in the Sherman function are provided to study the collision dynamics. The optical potential model incorporates the interactions of the incident electron and/or positron with both the nucleus and the bound electrons of the target atom. In-depth analyses of the spin asymmetry, which are sensitive to phases related interference effect, brought on by the various ingredients of the lepton-atom interaction, are also presented. The performance of the current approach to explain the observations, with the exception of the extremely low energy domain, is shown by a comparison of the previous experimental and theoretical results on this target atom. [ABSTRACT FROM AUTHOR]

Proton irradiations are highly sensitive to spatial variations, mainly due to their high linear energy transfer (LET) and densely ionizing nature. In realistic clinical applications, the targets of ionizing radiation are inhomogeneous in terms of geometry and chemical composition (i.e., organs in the human body). One of the main methods for proton range monitoring is to utilize the production of proton induced positron emitting radionuclides; these could be measured precisely with positron emission tomography (PET) systems. One main positron emitting radionuclide that could be used for proton range monitoring and verification was found to be 13N that produces a peak close to the Bragg peak. In the present work, we have employed the Monte Carlo method and Spectral Analysis (SA) technique to investigate the feasibility of utilizing the 13N peak for proton range monitoring and verification in inhomogeneous targets. Two different phantom types, namely, (1) ordinary slab and (2) MIRD anthropomorphic phantoms, were used. We have found that the generated 13N peak in such highly inhomogeneous targets (ordinary slab and human phantom) is close to the actual Bragg peak, when irradiated by incident proton beam. The feasibility of using the SA technique to estimate the distribution of positron emitter was also investigated. The current findings and the developed tools in the present work would be helpful in proton range monitoring and verification in realistic clinical radiation therapy using proton beams. [ABSTRACT FROM AUTHOR]

Theoretical investigation of the scattering of electrons and positrons from the plasma etching gas trifluoroiodomethane (CF 3 I) is presented in the present work. The investigation is carried out by taking into account the screening correction arising from a semiclassical analysis of atomic geometrical overlapping of the scattering cross-sections calculated in the independent atom approximation. The scattering system e ± -CF 3 I is studied through the calculations of the observable quantities, namely, absolute differential, Sherman function, total elastic and inelastic, momentum transfer, viscosity, ionization and total cross sections over the energy range 1 eV–1 MeV. Energy dependency of the differential cross section and Sherman function are also picturized in this work. A comparative study is carried out between scattering observables for electron impact with those for positron impact to get a better understanding of the interaction and dynamics of the collision process. The corresponding scattering quantities of the constituent atoms are calculated employing a complex optical model potential by solving the Dirac relativistic wave equations in the framework of partial wave analysis. The comparison of our results with the available experimental and theoretical data shows a reasonable agreement. [ABSTRACT FROM AUTHOR]

A cell-based therapy for the replacement of dopaminergic neurons has been a long-term goal in Parkinson's disease research. Here, we show that autologous engraftment of A9 dopaminergic neuron-like cells induced [...]