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  • Articles  (11)
  • 78.70  (11)
  • Springer  (11)
  • American Geophysical Union (AGU)
  • Annual Reviews
  • 1980-1984  (11)
  • 1935-1939
  • 1982  (11)
  • Physics  (11)
Collection
  • Articles  (11)
Source
Keywords
Publisher
  • Springer  (11)
  • American Geophysical Union (AGU)
  • Annual Reviews
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  • 1980-1984  (11)
  • 1935-1939
Year
Topic
  • 1
    Electronic Resource
    Electronic Resource
    Binding of gas atoms to extended crystal defects in molybdenum studied by positrons (1982)
    Springer
    Applied physics 27 (1982), S. 247-250 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 61.80 ; 71.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The positron annihilation technique (P.A.T.) has been used in a study of interactions between gas impurities and crystal defects (vacancy loops and voids) in molybdenum. P.A.T. measurements were found to be very effective for this purpose. We propose that the observed effects are due to decoration of the void surface with nitrogen and vacancy loop decoration with hydrogen and nitrogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619087
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  • 2
    Electronic Resource
    Electronic Resource
    Vacancy-impurity interaction in dilute iron alloys by positron annihilation (1982)
    Springer
    Applied physics 28 (1982), S. 179-187 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 61.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron annihilation measurements of the coincidence count rate at the peak of the angular correlation curve (CCR) have been performed as a function of temperature for the alloy systemFeTi in a concentration range up to about 1.3 at. %. The concentration dependence of the effective vacancy formation enthalpy (H 1V F )eff suggests the existence of an attractive interaction between vacancies and the impurity atoms. It will be shown that the description of the vacancy concentration in an alloy according to the Lomer model is not valid in this case, because it neglects binding of vacancies to solute atom pairs and to higher agglomerates. The application of a model proposed by Dorn and Mitchell gives evidence that beyond the binding of a vacancy to a single solute atom in the concentration range investigated also aggregates of a vacancy bound to two and three foreign atoms must be taken into account. The analysis of the measurements according to the method of Hehenkamp and Sander gives values for the respective vacancy-solute-atom(s) binding enthalpies H 1 B =0.25eV, H 2 B =0.53eV and H 3 B =0.91eV. The discussion of the temperature and solute-atoms concentration dependence of the vacancy concentration suggests a much more complicated behaviour than for pure metals even at low solute-atom concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617984
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  • 3
    Electronic Resource
    Electronic Resource
    On the trapping of positrons in cadmium in the temperature range from 80 to 330 K (1982)
    Springer
    Applied physics 27 (1982), S. 257-261 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 61.70 ; 81
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The positron lifetime was measured in cadmium in the temperature range between 80 K and 500 K. For the first time a plateau was observed by this method in polycrystalline samples. The obtained data are well explained by depletion of shallow traps forT≤180 K and by self-trapping in the prevacancy region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00619089
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of bcc-fcc phase transition on the compton profiles of iron (1982)
    Springer
    Applied physics 28 (1982), S. 119-122 
    Details
    ISSN: 1432-0630
    Keywords: 71.25P ; 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The effect of theα-γ or bcc-fcc phase transition on the electron momentum distribution and Compton profiles of iron has been theoretically examined by a band structure calculation in the two phases. The calculated band Compton profile for the bcc phase shows a good agreement with the experimental results by Phillips and Weiss. The calculated directional Compton profiles show significant changes while going from the bcc to the fcc phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617141
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  • 5
    Electronic Resource
    Electronic Resource
    Positron lifetime measurements on electron irradiation damage in amorphous Pd80Si20 and Cu50Ti50 alloys (1982)
    Springer
    Applied physics 27 (1982), S. 31-33 
    Details
    ISSN: 1432-0630
    Keywords: 61.40 ; 61.80 ; 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron lifetime measurements were performed on amorphous Pd80Si20 and Cu50Ti50 alloys irradiated with 3MeV electrons at 20K. The irradiation was found to increase the mean positron lifetime in both specimens indicating the presence of vacancy-like radiation damage. Isochronal annealing between 77 K and 300 K resulted in a continuous reduction of the positron lifetime, which suggests a gradual recovery of the irradiation induced defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197543
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  • 6
    Electronic Resource
    Electronic Resource
    Positron reemission brightness enhancement method (1982)
    Springer
    Applied physics 29 (1982), S. 93-98 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 79.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Numerical results are presented for a one-dimensional diffusion model for freely diffusing positrons in thin films with an initial exponential positron profile. The results are for two boundary conditions which are experimentally realizable. Since thermalized positrons generally obey this diffusion model, it should be possible to extract the bulk diffusion constant by fitting experimental measurements to the model's predictions. Recently, a scheme has been proposed for the brightness enhancement of slow positron beams. We discuss experimental methods for implementing this scheme and the various problems that may arise.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00632434
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  • 7
    Electronic Resource
    Electronic Resource
    Positron implantation profile in nickel (1982)
    Springer
    Applied physics 29 (1982), S. 99-103 
    Details
    ISSN: 1432-0630
    Keywords: 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A method for measurement of the positron implantation profile in the geometry employed in most positron annihilation experiments is described. The method is applied to the case of Ni as absorber and22Na as positron emitter. The experimental accuracy is discussed and a proposal for its improvement is outlined. Since absorption studies of positrons is usually performed in geometries quite different from the present, we give a short discussion on the impact of these differences on the transmission curves obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00632435
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  • 8
    Electronic Resource
    Electronic Resource
    Positron annihilation and Hall effect in electron irradiatedn-InP crystals (1982)
    Springer
    Applied physics 29 (1982), S. 219-223 
    Details
    ISSN: 1432-0630
    Keywords: 61.80 ; 71.55 ; 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron annihilation and Hall effect inn-InP crystals as a function of electron irradiation up to 1 · 1019 cm−2 and post-irradiated isochronal annealing up to 550 °C have been studied. It is concluded that in irradiatedn-InP samples positrons interact with negatively charged acceptor-type defect with level atE c −0.33 eV, probablyV In (primary defect). In post-irradiated isochronal annealed (up to 330 °C) samples ofn-InP positron trapping occurs preferably in secondary defects-vacancy clusters, which are formed in the temperature range (150–300 °C). Inn-InP crystals containing radiation induced defects the trapping rate was found to decrease with temperature in the range (300–77) K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615071
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  • 9
    Electronic Resource
    Electronic Resource
    Trapping of positrons at vacancies in magnesium (1982)
    Springer
    Applied physics 27 (1982), S. 49-56 
    Details
    ISSN: 1432-0630
    Keywords: 61.70 ; 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Trapping of positrons at vacancy-type defects in magnesium was studied by positron lifetime and Doppler-broadening measurements. Vacancy defects were produced by quenching, electron irradiation and deformation at low temperatures as well as by thermal agitation at elevated temperatures. In the first three cases we observed trapping at multiple vacancies, which anneal out between 77...400 K. Thermal equilibrium measurements show S-shape behaviour originating from positron trapping at magnesium monovacancies. However, changes in the positron parameters were very small, which is due to the weakness of the positron-vacancy interaction. A detrapping analysis yielded a positron-vacancy binding energy of the order of 0.3...0.4 eV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01197546
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  • 10
    Electronic Resource
    Electronic Resource
    Isothermal annealing of room temperature deformed iron studied with the positron annihilation technique (1982)
    Springer
    Applied physics 27 (1982), S. 129-132 
    Details
    ISSN: 1432-0630
    Keywords: 61.70 ; 78.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Positron-annihilation lineshape parameter measurements were performed during isothermal annealing of room temperature deformed iron. An isothermal annealing effect is seen in impure iron while in pure iron no effect is measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616662
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  • 11
    Electronic Resource
    Electronic Resource
    Positron trapping at grain boundaries (1982)
    Springer
    Applied physics 27 (1982), S. 149-152 
    Details
    ISSN: 1432-0630
    Keywords: 78.70 ; 61.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A simple model is developed for the trapping of positrons at grain boundaries. It is shown that there is a linear relationship between any linear annihilation parameter and the inverse grain size. An effective grain boundary width is defined, which depends on the positron diffusion length and on the strength of the grain boundary for positrons. The effect of detrapping on this effective width is also considered. The model is tested by using the experimental results available in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616665
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