Influence of Arsenic Pressure on the Doping of Gallium Arsenide with Germanium

THE doping of III-V compounds with elements from the IVth column of the periodic table has been studied under standard conditions of preparation by several investigators. In most cases, the IV element was found to act as an n-type dopant of low doping efficiency, a result that is usually interpreted to mean that more of the impurity atoms are located on the III element sublattice than on the V element sublattice. Causes for the unequal distribution of impurity atoms between the two sublattices have been sought in the sizes of the atoms and in their binding energies. An additional influence on the impurity atom distribution, namely, the vapor pressure of the V element, is considered in this note. A simple estimate will be given of the magnitude expected for the pressure effect, followed by some qualitative results for Ge-doped GaAs

Heavy-light meson in anisotropic lattice QCD

We examine whether the $O(a)$ improved quark action on anisotropic lattices can be used as a framework for the heavy quark, which enables precision computation of matrix elements of heavy-light mesons. To this end, it is crucial to verify that a mass independent and nonperturbative tuning of the parameters is possible. As a first step, we observe the dispersion relation of heavy-light mesons on a quenched lattice using the action which is nonperturbatively tuned only for the leading terms. On a lattice with the spatial cutoff $a_\sigma^{-1} \simeq$ 1.6 GeV and the anisotropy $\xi=4$, the relativity relation holds within 2% accuracy in the quark mass region $a_\sigma m_Q \leq 1.2$ with the bare anisotropy parameter tuned for the massless quark. We also apply the action to a calculation of heavy-light decay constants in the charm quark mass region.Comment: Lattice2002(heavyquark), 3 pages, 2 figure

Study of Scalar Mesons and Related Radiative Decays

After a brief review of the puzzling light scalar meson sector of QCD, a brief summary will be given of a paper concerning radiative decays involving the light scalars. There, a simple vector meson dominance model is constructed in an initial attempt to relate a large number of the radiative decays involving a putative scalar nonet to each other. As an application it is illustrated why $a_0(980)-f_0(980)$ mixing is not expected to greatly alter the $f_0/a_0$ production ratio for radiative $\phi$ decays.Comment: 9 pages, 3 figures, Talk presented at SUNYIT (Utica/NY) conference on High Energy Physics, June 6, 200

Development of space stable thermal control coatings for use on large space vehicles

The development of a large scale manufacturing method for the production of a stable zinc orthotitanate pigment by means of an oxalate co-precipitation method is examined. Pigments were prepared at various temperatures, and major emphasis was placed on the determination of the important parameters of post-precipitation firing and treatment. A large-scale process for the modification of a glass resin binder was developed and paints were formulated using the binder

The Synthesis, Resolution and Configuration of Beta-hydroxyvaline

Synthesis, resolution, and configuration of alpha-hydroxyvalin

RPA for Light-Front Hamiltonian Field Theory

A self-consistent random phase approximation (RPA) is proposed as an effective Hamiltonian method in Light-Front Field Theory (LFFT). We apply the general idea to the light-front massive Schwinger model to obtain a new bound state equation and solve it numerically.Comment: A major revision in presentation, while the results essentially unchanged. 2 figs. replaced, 1 fig. added, some parts of Sec. V moved to Sec. IV, some wording changed, typos correcte