Doppler Broadening Measurement of Positron Annihilation in Alkali Halides

1978 ◽  
Vol 44 (1) ◽  
pp. 204-210 ◽  
Author(s):  
Yasukazu Yoshizawa ◽  
Kiyoshi Shizuma ◽  
Toshiaki Fujita ◽  
Masato Nishi
Keyword(s):  
Positron Annihilation ◽  
Alkali Halides ◽  
Doppler Broadening

Positron annihilation in the alkali halides

1978 ◽  
Vol 56 (11) ◽  
pp. 1453-1460 ◽  
Author(s):  
D. P. Kerr ◽  
S. Dannefaer ◽  
G. W. Dean ◽  
B. G. Hogg
Keyword(s):  
Positron Annihilation ◽  
Negative Ions ◽  
Alkali Halides ◽  
Annihilation Rate ◽  
Doppler Broadening ◽  
Initial State ◽  
Almost All ◽  
Doppler Broadening Spectra

Position lifetime spectra and Doppler broadening spectra have been measured for 17 alkali halides. Three significant lifetime components are found in almost all cases. The results are interpreted in terms of a model in which a fraction of the positrons form positronium and the remainder are initially in a state from which either annihilation or transitions may occur. The annihilation rate from the initial state is shown to depend on the distance separating negative ions, which suggests that the positron is in a bound state.Deconvoluted Doppler broadening data indicate that at least two momentum components are present.

Positron annihilation in 60Co irradiated alkali halides

1978 ◽  
Vol 56 (12) ◽  
pp. 1527-1530 ◽  
Author(s):  
S. Dannefaer ◽  
D. P. Kerr ◽  
G. W. Dean ◽  
B. G. Hogg
Keyword(s):  
Experimental Data ◽  
Positron Annihilation ◽  
Momentum Distribution ◽  
Positron Lifetime ◽  
Alkali Halides ◽  
Systematic Investigation ◽  
Theoretical Treatment ◽  
Doppler Broadening ◽  
Lifetime Component ◽  
Gamma Irradiated

A systematic investigation of 17 gamma-irradiated alkali halides using positron lifetime and Doppler broadening techniques has been performed. For eight of the alkali halides (NaCl, NaBr, KCl, KBr, KI, RbCl, RbBr, and RbI), a new lifetime with values between 1.0 and 1.3 ns is attributed to positrons trapped in F centres. Despite large F centre concentrations in LiF, LiCl, LiBr, and NaF, no such lifetime component is observed in these samples. Doppler broadening measurements show that in nearly all cases the momentum distribution becomes narrower upon irradiation. The experimental data are discussed in view of a recent theoretical treatment of the positron – F centre problem.

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

Ion implantation of58Co for positron-annihilation Doppler-broadening measurements

1981 ◽  
Vol 24 (1) ◽  
pp. 67-69 ◽  
Author(s):  
M. J. Fluss ◽  
M. K. Chason ◽  
J. L. Lerner ◽  
D. G. Legnini ◽  
L. C. Smedskjaer
Keyword(s):  
Ion Implantation ◽  
Positron Annihilation ◽  
Doppler Broadening

scholarly journals Calculation of the Doppler broadening of the electron-positron annihilation radiation in defect-free bulk materials

2000 ◽  
Vol 61 (15) ◽  
pp. 10092-10099 ◽  
Author(s):  
V. J. Ghosh ◽  
M. Alatalo ◽  
P. Asoka-Kumar ◽  
B. Nielsen ◽  
K. G. Lynn ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Annihilation Radiation ◽  
Doppler Broadening ◽  
Bulk Materials ◽  
Electron Positron Annihilation ◽  
Electron Positron

The Evolution Behavior of Defects in the Nanofilms of W/Cu and W Probed by Doppler Broadening Positron Annihilation Spectroscopy

2017 ◽  
Vol 373 ◽  
pp. 104-107
Author(s):  
Ling Wang ◽  
Ai Hong Deng ◽  
Kang Wang ◽  
Yong Wang ◽  
Xiao Bo Lu ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Storage Time ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Radio Frequency Magnetron Sputtering ◽  
Helium Ions ◽  
Near Surface ◽  
Evolution Behavior

W/Cu multilayer nanofilms and pure W nanofilms were prepared in pure Ar and He/Ar mixing atmosphere by radio frequency magnetron sputtering method. The defect evolution of the samples was characterized by Doppler broadening positron annihilation spectroscopy (DB-PAS).The results show that plenty of defects can be produced by introducing helium (He) into W/Cu multilayer nanofilms. With the natural storage time increasing, the helium located in the near surface of W/Cu multilayer nanofilm would be released gradually and induce the coalescence of the helium related defects due to the diffusion of the helium and defects. In addition, the pure W nanofilms were irradiated by 30 keV helium ions and 40 keV hydrogen (H) ions in sequence at room temperature. From the DB-PAS analysis, it can be shown that a large number of vacancy-type defects are produced due to the He and/or H irradiation. H ions would be trapped by He related defects and produced He-H-V complexes.

Sign in / Sign up

Export Citation Format

Share Document