Magnetotransport Properties of  AlxIn1-xAsySb1-y/GaSb and Optical Properties of GaAs1-xSbx

Magnetotransport Properties of AlxIn1-xAsySb1-y/GaSb and Optical Properties of GaAs1-xSbx

Date: May 2003
Creator: Lukic- Zrnic, Reiko
Description: Multilayer structures of AlxIn1-xAsySb1-y/GaSb (0.37 £ x £ 0.43, 0.50 £ y £ 0.52), grown by molecular beam epitaxy on GaSb (100) substrates were characterized using variable temperature Hall and Shubnikov-de Haas techniques. For nominally undoped structures both p and n-type conductivity was observed. The mobilities obtained were lower than those predicted by an interpolation method using the binary alloys; therefore, a detailed analysis of mobility versus temperature data was performed to extract the appropriate scattering mechanisms. For p-type samples, the dominant mechanism was ionized impurity scattering at low temperatures and polar optical phonon scattering at higher temperatures. For n-type samples, ionized impurity scattering was predominant at low temperatures, and electron-hole scattering dominated for both the intermediate and high temperature range. Analyses of the Shubnikov-de Haas data indicate the presence of 2-D carrier confinement consistent with energy subbands in GaAszSb1-z potential wells. Epilayers of GaAs1-xSbx (0.19<x<0.71), grown by MBE on semi-insulating GaAs with various substrate orientations, were studied by absorption measurements over the temperature range of 4-300 K. The various substrate orientations were chosen to induce different degrees of spontaneous atomic ordering. The temperature dependence of the energy gap (Eg) for each of these samples was modeled using three semi-empirical ...
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Plan for the Future of Neutron Research on Condensed Matter : An Argonne National Laboratory Report Prepared in Response to the "Report of the Review Panel on Neutron Scattering"

Plan for the Future of Neutron Research on Condensed Matter : An Argonne National Laboratory Report Prepared in Response to the "Report of the Review Panel on Neutron Scattering"

Date: January 27, 1981
Creator: Argonne National Laboratory
Description: The Review Panel on Neutron Scattering has recommended an expanded budget to allow systematic development of the field. An alternative plan for the future of neutron research on condensed matter is presented here, in case it is not possible to fund the expanded budget. This plan leads, in a rational and logical way, to a world-class neutron source that will ensure the vitality of the field and exploit the many benefits that state-of-the-art neutron facilities can bring to programs in the materials and biological sciences.
Contributing Partner: UNT Libraries Government Documents Department
Time-Independent One-Speed Neutron Transport Equation with Anisotropic Scattering in Absorbing Media

Time-Independent One-Speed Neutron Transport Equation with Anisotropic Scattering in Absorbing Media

Date: June 1980
Creator: Hangelbroek, Rutger Jan
Description: This report treats the time-independent, one-speed neutron transport equation with anisotropic scattering in absorbing media. For nuclear gain operators existence and uniqueness of solutions to the half-space and finite-slab problems are proved in L₂-space. The formulas needed for explicit calculations are derived by the use of perturbation theory techniques.
Contributing Partner: UNT Libraries Government Documents Department
Inelastic-Collision Cross Sections for Ne

Inelastic-Collision Cross Sections for Ne

Date: 1976
Creator: Soong, S. C. & Kim, Y. K.
Description: Cross sections for inelastic collisions of slow electrons and the dipole oscillator-strength distribution for the neon atom are given in tabular form. The results are based on experimental data that were checked and adjusted for internal consistency.
Contributing Partner: UNT Libraries Government Documents Department
Approximations of Gamma Cross Sections for Fast Nuclear Reactors

Approximations of Gamma Cross Sections for Fast Nuclear Reactors

Date: 1978?
Creator: Grimm, K. N. & Meneghetti, D.
Description: The report shows a method to approximate a P₁ scattering solution for the flux in a fast reactor, using an isotropic, but not a diagonal-transport-approximation scattering matrix. Presented are flux errors relative to a P₁ solution for different levels of transport approximation in an EBR-II type of core surrounded by a stainless steel reflector. Problems associated with the use of the method are also presented.
Contributing Partner: UNT Libraries Government Documents Department
VARIANT: VARIational Anisotropic Nodal Transport for Multidimensional Cartesian and Hexagonal Geometry Calculation

VARIANT: VARIational Anisotropic Nodal Transport for Multidimensional Cartesian and Hexagonal Geometry Calculation

Date: October 1995
Creator: Palmiotti, G.; Lewis, E. E. & Carrico, C. B.
Description: The theoretical basis, implementation information and numerical results are presented for VARIANT (VARIational Anisotropic Neutron Transport), a FORTRAN module of the DIF3D code system at Argonne National Laboratory. VARIANT employs the variational nodal method to solve multigroup steady-state neutron diffusion and transport problems. The variational nodal method is a hybrid finite element method that guarantees nodal balance and permits spatial refinement through the use of hierarchical complete polynomial trial functions. Angular variables are expanded with complete or simplified P₁, P₃ or P₅5 spherical harmonics approximations with full anisotropic scattering capability. Nodal response matrices are obtained, and the within-group equations are solved by red-black or four-color iteration, accelerated by a partitioned matrix algorithm. Fission source and upscatter iterations strategies follow those of DIF3D. Two- and three-dimensional Cartesian and hexagonal geometries are implemented. Forward and adjoint eigenvalue, fixed source, gamma heating, and criticality (concentration) search problems may be performed.
Contributing Partner: UNT Libraries Government Documents Department