Beam-based age-momentum correlation studies of positronium spin conversion in paramagnetic solutions and of positron trapping at defects in diamonds
| Autor: | H. Haricharun, P. Wesolowski, G. Duplâtre, Hermann Stoll, K. Bharuth-Ram, Elias Sideras-Haddad, Karin Maier, Janos Major, J.P.F. Sellschop, Markus Koch, Alfred Seeger, Isabelle Billard, J. Ch. Abbé, U. Lauff, Simon Henry Connell |
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| Přispěvatelé: | Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Heyd, Yvette |
| Rok vydání: | 1994 |
| Předmět: |
Paramagnetism
Positron Chemistry Positron Lifetime Spectroscopy Annihilation radiation Physics::Accelerator Physics [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] Trapping Atomic physics Spin (physics) [PHYS.PHYS.PHYS-CHEM-PH] Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph] Positronium Doppler broadening |
| Zdroj: | Slow Positron Beam Techniques for Solids and Surfaces Slow Positron Beam Techniques for Solids and Surfaces: International Workshop 5 Slow Positron Beam Techniques for Solids and Surfaces: International Workshop 5, Aug 1992, Jackson Hole, United States. pp.179-189 |
| ISSN: | 0094-243X |
| DOI: | 10.1063/1.45490 |
| Popis: | Correlated measurements of the lifetime and of the Doppler broadening of the 511 keV annihilation radiation of positrons (Age‐Momentum Correlation, AMOC) using an MeV positron beam have become a powerful tool for investigating reactions of positrons or positronium as a function of time. The room‐temperature reaction rate of the spin conversion of positronium in methanol induced by the presence of a paramagnetic solute (HTEMPO) has been found to be proportional to the HTEMPO concentration with a reaction‐rate constant of (22.5±0.5)⋅109 l mol−1 s−1 up to the highest concentration investigated (C≤0.1 mol/l). By means of the AMOC technique it was shown that a large Doppler broadening in natural and synthetic diamonds is correlated with a very short lifetime component. At higher positron ages a second positron state with a narrower momentum distribution of the positron‐electron pair indicates positron trapping at defects with concentrations ranging from 10−7 to 10−6 in different types of diamonds. |
| Databáze: | OpenAIRE |
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