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Full-Text Articles in Engineering

Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham May 2019

Calculation And Tabulation Of Efficiencies For Tungsten Foil Positron Moderators, R. Alsulami, M. Albarqi, S. Jaradat, Shoaib Usman, Joseph T. Graham

Mining and Nuclear Engineering Faculty Research & Creative Works

Monte Carlo radiation transport simulations were used to calculate the positron stopping profiles in tungsten positron moderator foils. Stopping profiles were numerically integrated with efficiency kernels derived from Green's function solutions of the 3D diffusion equation to determine the moderation efficiency in both the backscattering and transmission geometries. Stopping profiles and efficiencies were calculated for positron energies from 10 keV to 10 MeV and incident angles from 0° to 75°. The resulting efficiencies agreed with other calculated and measured values in the literature, especially when similar values of the positron diffusion length and surface emission branching ratio were used ...


Manipulating Transverse Photovoltage Across Plasmonic Triangle Holes Of Symmetry Breaking, Marjan Akbari, Jie Gao, Xiaodong Yang Apr 2019

Manipulating Transverse Photovoltage Across Plasmonic Triangle Holes Of Symmetry Breaking, Marjan Akbari, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The transverse photo-induced voltages generated by the photon drag effect under normally and obliquely incident circularly polarized light across the plasmonic symmetry-breaking isosceles-triangle holes and right-triangle holes have been characterized. It is observed that the sign of transverse photovoltage flips when the incident circular polarization is switched for both types of plasmonic triangle holes. However, the unbalanced photovoltage between two circular polarizations is achieved across the plasmonic right-triangle holes, compared to the balanced photovoltage in the plasmonic isosceles-triangle holes. Such manipulation of the sign and the amplitude of transverse photovoltage is enabled by the broken symmetries of the electric and ...