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Saturday, July 11, 2020 | History

2 edition of Positron annihilation in methane. found in the catalog.

Positron annihilation in methane.

Peter M. Smith

Positron annihilation in methane.

by Peter M. Smith

  • 141 Want to read
  • 37 Currently reading

Published .
Written in English

    Subjects:
  • Physics Theses

  • Edition Notes

    Thesis (M.Sc.), Dept. of Physics, University of Toronto.

    ContributionsPaul, D. A. L. (supervisor)
    The Physical Object
    Pagination33 p.
    Number of Pages33
    ID Numbers
    Open LibraryOL18924389M

    When it comes to studying the structures and defects of materials, there is presently no technique that is superior to positron annihilation. The increasing demands for higher accuracy and reliability provide a constant stimulus to the field, and the present book relates the newest and most important scientific discoveries made in the field of positron is indexed by Thomson. The theoretical foundations of the interaction of positrons with matter are reviewed. The book describes in detail all important techniques of positron annihilation, such as positron lifetime spectroscopy, Doppler-broadening spectroscopy, the angular correlation of annihilation radiation, positron-beam applications, and also new s: 1.

    A positron is the antiparticle of an electron. It has the same mass but an opposite charge to that of the electron. Dirac introduced an idea of the positive electron in (Dirac, ), and, soon after, Anderson found it, that was the positron, in during observation of radiations from the universe, as shown in Figure (Anderson, ). Bound electron contribution to the Doppler-shift of gamma-ray spectra in the positron-electron annihilation process of molecular methane has been studied in gas phase. Two accurate ab initio quantum mechanical schemes, i.e. the delocalized molecular orbital (MO) and the localized natural.

    Energy-resolved positron-molecule annihilation: Vibrational Feshbach resonances and bound states by Levi Daniel Barnes Doctor of Philosophy in Physics University of California, San Diego, Professor Clifford M. Surko, Chair This thesis describes a new technique for the measurement of positron an-. A. T. Stewart admixtures angular correlation curves angular distribution annihilation rate approximation argon benzene Berko Bisi bound bubble calculated Canad CCl4 Celitans collisions concentration conduction electrons core cross section DeBenedetti decay density Department of Physics dependence electric field energy equation experimental.


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Positron annihilation in methane by Peter M. Smith Download PDF EPUB FB2

Positron Annihilation focuses on the process of positron annihilation in different environments. Partitioned into two parts with 42 chapters, the book contains the contributions of authors who have done research on the annihilation of positrons, which brought about valuable information on the properties of Edition: 1.

The annihilation of positrons in methane gas at room temperature has been measured at pressures below 2 atm. The annihilation rate for the free positron component is proportional to the gas density and corresponds to an effective number of electrons per molecule taking part in annihilation, Z eff  =  ±  (standard error).Cited by: The book describes in detail all important techniques of positron annihilation, such as positron lifetime spectroscopy, Doppler-broadening spectroscopy, the angular correlation of annihilation radiation, positron-beam applications, and also new methods.

Abstract. Positron lifetime spectra have been measured in methane gas at 23 °C over a density range of × to × g/cm tical analysis of the data yields a 1 Z eff of +/- for orthopositronium and a Z eff of +/- for positrons which do not form positronium. Several annihilation mechanisms are discussed in connection with the data.

Positron Annihilation focuses on the process of positron annihilation in different environments. Partitioned into two parts with 42 chapters, the book contains the contributions of authors who have done research on the annihilation of positrons, which brought about valuable information on the properties of matter.

Measurements of positron annihilation rates at room temperature under the influence of an applied electric field have been made in methane at different pressures.

The experiments were all carried out in the linear region in which the annihilation rate is accurately proportional to gas by: 2. Positron annihilation in methane gas Article (PDF Available) in Canadian Journal of Physics 48(24) February with 21 Reads How we measure 'reads'.

The subject of this book is the investigation of lattice imperfections in semiconductors by means of positron annihilation. A comprehensive review is given of the different positron techniques, whose application to various kinds of defects, e.g.

vacancies, impurity-vacancy complexes and dislocations, is described. The sensitivity range of positron annihilation with respect to the detection of. Annihilation rates have been measured for positrons in methane gas at temperatures of 22,−28, and −50°C at densities in the range ×10 −4 −×10 −1 g/cm 3, in and −28°C methane gas as a function of applied electric field strength and gas density, and in 22°C methane−argon gas mixtures as a function of argon concentration.

A complex dependence of the slow. Positron annihilation lifetime and Doppler broadening energy spectra have been measured in methane physisorbed on grafoil surfaces at 77 K as a function of surface coverage (0 to monolayers).

Both surface positron lifetime and Doppler broadening S (central) parameters vary as a function of coverage. Positron Annihilation 5 Figure 3: The x-axis is position along the scan direction and the y-axis is the count rate.

Panel A shows the response to an isotropically radiating source. The width of the base is cm is the width of the slit. Panel B shows the distribution of gamma rays from the source.

Panel C shows the convolution of these 2. The electron-positron-pair annihilation in the bipositronium PS2 is considered.

In particular, the two- three- one- and zero-photon annihilation rates are determined to high accuracy. The corresponding analytical expressions are also presented. Also, a large number of bound state properties have been determined for this system.

We have measured the rates of positron annihilation in synthetic zeolites 4A and 13X under a variety of conditions. For zeolites 4A and 13X, respectively, long lifetime values (τ 2 in nanoseconds) and intensities I 2 (listed in parentheses) were found as follows: hydrated, ± (%) and ± (%); evacuated, ± (%) and ± (%); filled.

Review from Ringgold Inc., ProtoView: This collection of thirty-four papers on nuclear physics, originally delivered at the thirty-ninth Polish Seminar on Positron Annihilation held in Kazimierz Dolny, Poland in Juneshowcases current research, theory and experimentation in electron-positron annihilation.

The papers are divided into four sections examining theoretical calculations. Abstract Positron annihilation lifetime and Doppler broadening energy spectra have been measured in methane physisorbed on grafoil surfaces at 77 K as a function of surface coverage (0 to monolayers).

Both surface positron lifetime and Doppler broadening. This website is a result of a collaborative venture among various researchers working world-wide in the area of positron annihilation. It provides information on different aspects of positron annihilation techniques and its applications in various disciplines such as materials science, atomic physics, astronomy, plasma physics, biological science etc.

Abstract. A positron is the antiparticle of an electron. It has the same mass, spin and absolute value of the electric charge as an electron. Therefore, the processes the characteristic time of which is less than lifetime of a positron in a medium have a lot of common features with the.

The positively charged hydrogen atoms produce repulsive Coulomb potentials to a positron. Both the MO and NBO schemes further reveal that the 2a 1 electrons of methane, that is, the 2a 1 electron component of the C H bonds rather than the whole C H bonds of methane, predominates the positron–electron annihilation gamma-ray spectra of the Cited by: Correspondence Dr.

Farida Selim, conference chair Phone: +1 () Email: [email protected] 18th International Conference on Positron Annihilation August| Orlando, USA Please register to attend talks on positron annihilation spectroscopy topics, to say hello to colleagues in person, and visit the Kennedy Space Center as part of your conference registration.

Annihilation rates have been measured for positrons in methane gas at temperatures of 22,−28, and −50°C at densities in the range ×10−4−×10−1 g/cm3, in and −28°C. Positron Annihilation in Chemistry gives a critical review of the chemistry-oriented positron annihilation research.

The only three light particles participating in low energy physics and chemistry are the electron, positron, and positronium. Positronium (Ps) is the most important "anomalous" atom.Abstract. Annihilation rates have been measured for positrons in methane gas at temperatures of 22, and °C at densities in the range ×× g/cm 3, in and °C methane gas as a function of applied electric field strength and gas density, and in 22°C methane-argon gas mixtures as a function of argon concentration.A complex dependence of the slow positron.Some theoretical aspects, practical results and experimental techniques of use of the positron annihilation phenomena in the research of the structure, defects of structure and other properties of different materials and mediums are covered in this journal volume.

It comprises the papers presented at the 17th International Conference on Positron Annihilation (ICPA, Wuhan, China,