Anisotropic positronium in crystalline quartz

Th Gessmann, J. Major, A. Seeger, J. Ehmann

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Positronium (Ps = (e+e-)) in synthetic crystalline quartz is investigated by means of the positron spin relaxation (e+SR) technique. The set-up employed measures the change in the Doppler broadening of the 511 kev annihilation photon line caused by the reversal of large magnetic fields applied along the spin polarization axis of positrons (e+) emitted from a 68Ge/68Ga source. In contrast with other methods, the technique allows the detection of Ps in condensed matter even if the Ps-forming e+ fraction r is quite small. Moreover, because in single crystals the magnetic field defines a preferred crystallographic direction, the e+SR technique permits the study of the anisotropy of the hyperfine interaction of Ps in matter. The theory necessary to deduce the Ps hyperfine tensor from the e+SR measurements is developed. Room-temperature measurements show that in synthetic quartz crystals (i) the Ps-forming e+ fraction is r = 0.15, (ii) the electron density at the e+ in Ps is about 0.3 of the vacuum value and, (iii) the Ps hyperfine interaction is strongly anisotropic. The relationship of the last-mentioned result to the much smaller anisotropy of the muonium hyperfine interaction is discussed.

Original languageEnglish
Pages (from-to)771-791
Number of pages21
JournalPhilosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties
Volume81
Issue number8
DOIs
Publication statusPublished - Aug 2001

Fingerprint

Quartz
positronium
Positrons
Anisotropy
quartz
Magnetic fields
Crystalline materials
Spin polarization
positrons
Doppler effect
Temperature measurement
Tensors
Carrier concentration
muonium
anisotropy
Photons
Single crystals
interactions
Vacuum
quartz crystals

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physics and Astronomy(all)

Cite this

Anisotropic positronium in crystalline quartz. / Gessmann, Th; Major, J.; Seeger, A.; Ehmann, J.

In: Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties, Vol. 81, No. 8, 08.2001, p. 771-791.

Research output: Contribution to journalArticle

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