Dipole trap model for the metallic state in gated silicon-inversion layers

In order to investigate the metallic state in high-mobility Si-MOS structures, we have further developed and precised the dipole trap model which was originally proposed by B.L. Altshuler and D.L. Maslov [Phys. Rev. Lett.\ 82, 145 (1999)]. Our additional numerical treatment enables us to drop several approximations and to introduce a limited spatial depth of the trap states inside the oxide as well as to include a distribution of trap energies. It turns out that a pronounced metallic state can be caused by such trap states at appropriate energies whose behavior is in good agreement with experimental observations.Comment: 16 pages, 10 figures, submitte

Generalized Fourier Integral Operators on spaces of Colombeau type

Generalized Fourier integral operators (FIOs) acting on Colombeau algebras are defined. This is based on a theory of generalized oscillatory integrals (OIs) whose phase functions as well as amplitudes may be generalized functions of Colombeau type. The mapping properties of these FIOs are studied as the composition with a generalized pseudodifferential operator. Finally, the microlocal Colombeau regularity for OIs and the influence of the FIO action on generalized wave front sets are investigated. This theory of generalized FIOs is motivated by the need of a general framework for partial differential operators with non-smooth coefficients and distributional data

Classes of generalized functions with finite type regularities

We introduce and analyze spaces and algebras of generalized functions which correspond to Hölder, Zygmund, and Sobolev spaces of functions. The main scope of the paper is the characterization of the regularity of distributions that are embedded into the corresponding space or algebra of generalized functions with finite type regularities

Building CMS Pixel Barrel Detectur Modules

For the barrel part of the CMS pixel tracker about 800 silicon pixel detector modules are required. The modules are bump bonded, assembled and tested at the Paul Scherrer Institute. This article describes the experience acquired during the assembly of the first ~200 modules.Comment: 5 pages, 7 figures, Vertex200

Field Effects at Protruding Defect Sites in Electrocatalysis at Metal Electrodes?

Potential dependencies of adsorption energies at metal electrodes are often interpreted in terms of a dipole-field interaction picture. Classical electrostatics would then suggest particularly strong dependencies at protruding defect sites like steps and kinks due to a local field enhancement. Here, we use first-principles density functional theory calculations that capture the capacitive charging of the electric double layer to analyze these dependencies for prototypical adsorbates at vicinal Pt(111) surfaces in an implicit aqueous electrolyte. This analysis confirms effective dipole-field-type dependencies but rationalizes why they can neither be estimated on the basis of accessible molecular dipoles nor the mere atomic-scale geometry of the adsorption site. The observed magnitude questions mechanistic analyses of surface catalytic reactions made on the basis of the prevalent computational hydrogen electrode approach that is agnostic to these potential-induced adsorption energy variations

Implicit Solvation Methods for Catalysis at Electrified Interfaces

Implicit solvation is an effective, highly coarse-grained approach in atomic-scale simulations to account for a surrounding liquid electrolyte on the level of a continuous polarizable medium. Originating in molecular chemistry with finite solutes, implicit solvation techniques are now increasingly used in the context of first-principles modeling of electrochemistry and electrocatalysis at extended (often metallic) electrodes. The prevalent ansatz to model the latter electrodes and the reactive surface chemistry at them through slabs in periodic boundary condition supercells brings its specific challenges. Foremost this concerns the difficulty of describing the entire double layer forming at the electrified solid–liquid interface (SLI) within supercell sizes tractable by commonly employed density functional theory (DFT). We review liquid solvation methodology from this specific application angle, highlighting in particular its use in the widespread ab initio thermodynamics approach to surface catalysis. Notably, implicit solvation can be employed to mimic a polarization of the electrode’s electronic density under the applied potential and the concomitant capacitive charging of the entire double layer beyond the limitations of the employed DFT supercell. Most critical for continuing advances of this effective methodology for the SLI context is the lack of pertinent (experimental or high-level theoretical) reference data needed for parametrization

Topological properties of regular generalized function algebras

We investigate density of various subalgebras of regular generalized functions in the special Colombeau algebra of generalized functions.Comment: 6 page

CMS Barrel Pixel Detector Overview

The pixel detector is the innermost tracking device of the CMS experiment at the LHC. It is built from two independent sub devices, the pixel barrel and the end disks. The barrel consists of three concentric layers around the beam pipe with mean radii of 4.4, 7.3 and 10.2 cm. There are two end disks on each side of the interaction point at 34.5 cm and 46.5 cm. This article gives an overview of the pixel barrel detector, its mechanical support structure, electronics components, services and its expected performance.Comment: Proceedings of Vertex06, 15th International Workshop on Vertex Detector