Positron spin-relaxation (e+SR) study of carbon phases, SiC, and fused quartz

Th Gessmann, J. Major, A. Seger

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The positron spin-relaxation (e+SR) method permits the detectio and investigation of positronium (Ps) in condensed matter with very small formation probabilities. In a set-up that makes use of spin-polarized positrons emitted from a 68Ga/68 source, the effect of reversals of an external magnetic field applied longituginally to the positron spin polarizaton on the Doppler broadening of the annihilation photon line is measured. For the first time, the fractions r of Ps-forming positrons and normalized electron densities κ at the positron in Ps have been determined for natural type-IIa diamond (r =0.07, κ = 1) and crystalline SiC (r = 0.04, κ = 0.15). The two materials show a hitherto not observed anomalous dependence of the the Doppler broadening on the magnetic field strength that indicates that a large Ps fraction annihilates before becoming thermalized. Fused quartz (r = 0.67, κ = 1.4), C60 fullerite (r = 0.03, K = 0.6), and highly orientated pyrolytic graphite (r =0.01, κ = 0.7) showed the 'normal' field dependence.

Original languageEnglish
Pages (from-to)10493-10506
Number of pages14
JournalJournal of Physics Condensed Matter
Volume10
Issue number46
DOIs
Publication statusPublished - Nov 23 1998

Fingerprint

Quartz
Positrons
positronium
positrons
Carbon
quartz
carbon
Doppler effect
Magnetic fields
Diamond
Graphite
pyrolytic graphite
magnetic fields
Carrier concentration
Diamonds
field strength
Photons
diamonds
Crystalline materials
photons

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

Positron spin-relaxation (e+SR) study of carbon phases, SiC, and fused quartz. / Gessmann, Th; Major, J.; Seger, A.

In: Journal of Physics Condensed Matter, Vol. 10, No. 46, 23.11.1998, p. 10493-10506.

Research output: Contribution to journalArticle

@article{c9e0ac5a51ae495184fb0c961654fec7,
title = "Positron spin-relaxation (e+SR) study of carbon phases, SiC, and fused quartz",
abstract = "The positron spin-relaxation (e+SR) method permits the detectio and investigation of positronium (Ps) in condensed matter with very small formation probabilities. In a set-up that makes use of spin-polarized positrons emitted from a 68Ga/68 source, the effect of reversals of an external magnetic field applied longituginally to the positron spin polarizaton on the Doppler broadening of the annihilation photon line is measured. For the first time, the fractions r of Ps-forming positrons and normalized electron densities κ at the positron in Ps have been determined for natural type-IIa diamond (r =0.07, κ = 1) and crystalline SiC (r = 0.04, κ = 0.15). The two materials show a hitherto not observed anomalous dependence of the the Doppler broadening on the magnetic field strength that indicates that a large Ps fraction annihilates before becoming thermalized. Fused quartz (r = 0.67, κ = 1.4), C60 fullerite (r = 0.03, K = 0.6), and highly orientated pyrolytic graphite (r =0.01, κ = 0.7) showed the 'normal' field dependence.",
author = "Th Gessmann and J. Major and A. Seger",
year = "1998",
month = "11",
day = "23",
doi = "10.1088/0953-8984/10/46/016",
language = "English",
volume = "10",
pages = "10493--10506",
journal = "Journal of Physics Condensed Matter",
issn = "0953-8984",
publisher = "IOP Publishing Ltd.",
number = "46",

}

TY - JOUR

T1 - Positron spin-relaxation (e+SR) study of carbon phases, SiC, and fused quartz

AU - Gessmann, Th

AU - Major, J.

AU - Seger, A.

PY - 1998/11/23

Y1 - 1998/11/23

N2 - The positron spin-relaxation (e+SR) method permits the detectio and investigation of positronium (Ps) in condensed matter with very small formation probabilities. In a set-up that makes use of spin-polarized positrons emitted from a 68Ga/68 source, the effect of reversals of an external magnetic field applied longituginally to the positron spin polarizaton on the Doppler broadening of the annihilation photon line is measured. For the first time, the fractions r of Ps-forming positrons and normalized electron densities κ at the positron in Ps have been determined for natural type-IIa diamond (r =0.07, κ = 1) and crystalline SiC (r = 0.04, κ = 0.15). The two materials show a hitherto not observed anomalous dependence of the the Doppler broadening on the magnetic field strength that indicates that a large Ps fraction annihilates before becoming thermalized. Fused quartz (r = 0.67, κ = 1.4), C60 fullerite (r = 0.03, K = 0.6), and highly orientated pyrolytic graphite (r =0.01, κ = 0.7) showed the 'normal' field dependence.

AB - The positron spin-relaxation (e+SR) method permits the detectio and investigation of positronium (Ps) in condensed matter with very small formation probabilities. In a set-up that makes use of spin-polarized positrons emitted from a 68Ga/68 source, the effect of reversals of an external magnetic field applied longituginally to the positron spin polarizaton on the Doppler broadening of the annihilation photon line is measured. For the first time, the fractions r of Ps-forming positrons and normalized electron densities κ at the positron in Ps have been determined for natural type-IIa diamond (r =0.07, κ = 1) and crystalline SiC (r = 0.04, κ = 0.15). The two materials show a hitherto not observed anomalous dependence of the the Doppler broadening on the magnetic field strength that indicates that a large Ps fraction annihilates before becoming thermalized. Fused quartz (r = 0.67, κ = 1.4), C60 fullerite (r = 0.03, K = 0.6), and highly orientated pyrolytic graphite (r =0.01, κ = 0.7) showed the 'normal' field dependence.

UR - http://www.scopus.com/inward/record.url?scp=0343833900&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0343833900&partnerID=8YFLogxK

U2 - 10.1088/0953-8984/10/46/016

DO - 10.1088/0953-8984/10/46/016

M3 - Article

AN - SCOPUS:0343833900

VL - 10

SP - 10493

EP - 10506

JO - Journal of Physics Condensed Matter

JF - Journal of Physics Condensed Matter

SN - 0953-8984

IS - 46

ER -