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Sunday, July 19, 2020 | History

2 edition of positron beam system for the study of solids and surfaces. found in the catalog.

positron beam system for the study of solids and surfaces.

Stephen M. Hutchins

positron beam system for the study of solids and surfaces.

by Stephen M. Hutchins

  • 52 Want to read
  • 15 Currently reading

Published by University of East Anglia in Norwich .
Written in English


Edition Notes

Thesis (Ph.D.), University of East Anglia, School of Mathematics and Physics, 1985.

ID Numbers
Open LibraryOL13845158M

positron-beam experiments is that a large fraction. of. positrons can. diffuse. back. to. the surface and be emitted into the vacuum either as free positrons. or (after picking. up. an electron from the surface) as positronium atoms. The trapping. of. positrons by the image potential. at. the surface is also possible. The. positron slowing-down. y at interaction zone will be decisive whether a positron current of the order of positrons/s or more can be reached. Particle trajectories in a eld of a solenoid Solenoid elds are used to focus charged particle beams in beam lines for many applications. The propagation of beams in beam .

The monitoring of annihilation radiation by nuclear spectroscopic methods provides valuable information on the electron-positron system which can directly be related to the electronic structure of the medium. Since the positron is a positive electron its behavior in matter is especially interesting to solid-state and atomic physi­ cists.   1. Science. Oct 22;() Surface analysis and atomic physics with slow positron beams. Mills AP Jr. Recent advances in slow positron beam techniques are making it possible to study the interactions of low-energy positrons with gas molecules and solid surfaces and to measure the properties of free positronium atoms.

M. J. Puska and R. M. Nierninen: Positrons in solids and on solid surfaces its state develops in real space as a diffusion process, in which the positron interactions with phonons are quasi- elastic; i.e., the positron momentum distribution is con- served. During diffusion the positron interacts with de-fects in the solid, and trapping of the positron into a lo-. spin-polarized ‘slow’ positron beam by the Michigan group [4]. At that time, the surface physics was rapidly progressing accompanying the technological innovation such as ultra-high vacuum technology and the scanning tunneling microscopy. Novel phenomena were anticipated to occur at solid surfaces due to the dimension lowering.


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Positron beam system for the study of solids and surfaces by Stephen M. Hutchins Download PDF EPUB FB2

A personal overview is given of the advances in positron beam studies of solids and surfaces presented at the 10th International Workshop on Positron Beams, held in Doha, Qatar, in March Solids studied include semiconductors, metals, alloys Cited by: 2.

@article{osti_, title = {Positron beams for solids and surfaces}, author = {Schultz, P J and Massoumi, G R and Simpson, P J}, abstractNote = {This report contains papers on topics related to positron beam collisions with solids and surfaces.

The papers are divided into the following sections: scattering and implantation profiles; surfaces; defects and defect profiling, bulk solids and. International Workshop on Slow-Positron Beam Techniques for Solids & Surfaces (4th: London, Ont.). Positron beams for solids and surfaces.

New York: American Institute of Physics, (OCoLC) Material Type: Conference publication: Document Type: Book: All Authors / Contributors: Peter J Schultz; Guiti R Massoumi; Peter John.

positron-beam setup. The advantage is the analysis of the electronic structure at the surface, in thin epitaxial layers, or at nterfaces i (e.g.

Howell et al. ; Peng et al. The defect densities can be determined in a slow-positron system by a back-diffusion experiment in addition to the measuring principles of the momentumFile Size: KB. In this study, we describe an advanced multi-functional, variable-energy positron beam system capable of measuring the energies of multiple “positron-induced” electrons in coincidence with the Author: Christoph Hugenschmidt.

@article{osti_, title = {Interaction of positron beams with surfaces, thin films, and interfaces}, author = {Schultz, P J and Lynn, K G}, abstractNote = {Recent advances in the study of solid surfaces and thin films using variable-energy positron beams are reviewed.

In the first part the authors discuss the process of positron moderation and technical aspects of positron beam production. On the basis of the design and construction of the slow positron beam SPONSOR at the Helmholtz-Centre Dresden-Rossendorf an example is given how to build-up a simple slow positron beam for solid surface investigations within a short time and without high financial costs.

The system uses a 22Na source and consists of three main parts: (1) the source chamber with a thin film tungsten moderator. Proceedings of the Sixth International Workshop on Slow-Positron Beam Techniques for Solids and Surfaces (SLOPOS-6) May • Makuhari, Japan.

Doyama, T. Akahane, M. Fujinami Study of positron surface states on the alkali-metal-covered transition-metal surface select article Development of a new Monte Carlo simulation system.

Recent advances in slow positron beam techniques are making it possible to study the interactions of low-energy positrons with gas molecules and solid surfaces and to measure the properties of free positronium atoms. New surface related results include the observation of surfaces with negative positron affinity and the thermionic emission of slow positronium atoms, low-energy positron.

Doyama's research works with 3, citations and 1, reads, including: Elastic and Lattice Dynamical Properties of Metals Studied by N-Body Potential. At the University of Bath the positron laboratory is equipped with two magnetic-transport positron beam systems for depth profiling the structural, chemical and electronic properties of materials from the surface to depths of a few micrometres, and a project beam system for the study of fundamental positron-atom collision phenomena.

The e +-PALS spectrometer is dedicated to measuring positron lifetimes on the order observed in materials such as metals and semiconductors (i.e., lifetimes in the range of picoseconds or less).The instrument utilizes time varying electric fields to generate narrow bunches (beam is magnetically guided to the sample, which can be biased.

A positron beam system for the study of solids and surfaces Author: Hutchins, S. ISNI: X Awarding Body: University of East Anglia Current Institution: University of East Anglia Date of Award: Availability of Full Text. Within the last decade powerful methods have been developed to study surfaces using bright low-energy positron beams.

These novel analysis tools exploit the unique properties of positron interaction with surfaces, which comprise the absence of exchange interaction, repulsive crystal potential and positron trapping in delocalized surface states at low energies. By applying reflection high.

Abstract. The basic principles of positron annihilation physics are discussed and the four most important experimental techniques are described (i.e.

the positron lifetime, the angular correlation, the Doppler broadening, and the low-energy-positron beam techniques). An improved approach is presented for the analysis of positron beam Doppler broadening data. Instead of analyzing the energy‐dependent shape parameter, the so‐called S(E) data, we combined the shape S(E) and wing W(E) data by plotting them as a trajectory in the S–W plane, using the implantation energy as a running parameter.

It is shown that this plot is of particular interest for the. A systematic study of diffusion of positrons in several liquid and solid metals was performed with a vertical positron beam. The S parameter and positronium fraction was measured as a function of temperature in the solid and liquid phases for Ga, Bi, Na, Sn, In and Pb.

An appreciable change is observed in metals where positrons trapping is not observed in the solid just below the melting point. Case study of the Munich SPM G.Kögel Positron beam systems consist of those components discussed in the previous lecture. The necessary functional parts are arranged in series and the positrons are transferred by beam lines Source line 1 comp.

1 line 2 / / line n comp. n exper. Area. Download PDF: Sorry, we are unable to provide the full text but you may find it at the following location(s): (external link). International Workshop on Slow-Positron Beam Techniques for Solids & Surfaces (5th: Jackson Hole, Wyoming).

Slow positron beam techniques for solids and surfaces. New York: American Institute of Physics, © (OCoLC) Material Type: Conference publication, Internet resource: Document Type: Book, Internet Resource.

• positron beam of monoenergetic positrons can be used to study near-surface defect or epitaxial layers • depth range: surface à a few µm • sensitivity limit: 5´ cm-3to 5´ cm-3(negative monovacancies) references and more information can be found in “Positron Annihilation in Semiconductors” by R. Krause-Rehberg and H.S.Positron beam technology has developed in tandem with our understanding of positron-surface interactions to enable the positron to be used in novel and unique ways to study the physical and chemical properties of surfaces.

Most notable among the new positron spectroscopies are Low-Energy Positron Diffraction (LEPD) and Positron Annihilation.A study of irradiation-induced damage in HAVAR® foils was initiated in order to extract the highest proton dose the foils can sustain.

The lattice structure of HAVAR® foils in different metallurgic conditions is presented, as well as visible internal structure, measured by Transmission Electron Microscopy (TEM).

Positron Annihilation Spectroscopy (PAS) techniques were used to investigate.