Positron annihilation lifetime and coincidence Doppler broadening study of γ-irradiated polyethylene

2005 ◽  
Vol 313 (1-3) ◽  
pp. 63-69 ◽  
Author(s):  
R.S. Yu ◽  
T. Suzuki ◽  
N. Djourelov ◽  
K. Kondo ◽  
Yasuo Ito ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Study of Gamma Irradiation Effect on Unplasticized PVC by Positron Annihilation

2017 ◽  
Vol 373 ◽  
pp. 274-279
Author(s):  
Bao Yi Wang ◽  
Jing Yang ◽  
Xing Zhong Cao ◽  
Long Wei ◽  
Run Sheng Yu
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Reference Sample ◽  
Irradiation Effect ◽  
Doppler Broadening ◽  
Carbonyl Groups ◽  
Positron Annihilation Lifetime ◽  
Ratio Curve ◽  
Gamma Irradiated ◽  
Coincidence Doppler Broadening

Positron annihilation technique is used to study the gamma irradiation effect on unplasticized PVC (UPVC). Positron annihilation lifetime spectroscopy (PALS) results show that both the o-Ps lifetime and intensity decrease with the increase of gamma irradiation dose. By comparing Coincidence Doppler Broadening (CDB) results of four typical polymers using different reference sample, it is confirmed that CDB ratio curve can truthfully reflect the momentum difference of electrons which positrons annihilate with. The CDB results of gamma-irradiated UPVC using non-irradiated UPVC rather than commonly chosen LDPE as a reference sample show obvious oxygen peak, together with FTIR results, verify the appearance of carbonyl groups around the free volume.

Probing Materials by Positron Annihilation Technique and Mossbauer Spectroscopy - Review

2011 ◽  
Vol 699 ◽  
pp. 1-37
Author(s):  
Mahuya Chakrabarti ◽  
S. Chattopadhyay ◽  
D. Sanyal ◽  
A. Sarkar ◽  
D. Jana
Keyword(s):  
Magnetic Properties ◽  
Positron Annihilation ◽  
Room Temperature ◽  
Spectroscopic Studies ◽  
Spectroscopic Technique ◽  
Annihilation Radiation ◽  
Radiation Measurement ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Positron annihilation technique is a well known technique to characterize the defects in a material. These defects can be identified by positron annihilation lifetime and coincidence Doppler broadening of positron annihilation radiation measurement. In this chapter we report the room temperature positron annihilation lifetime for single crystalline ZnO. From our study it is confirmed that the present crystal contains VZn–hydrogen complexes with low open volumes. Another important nuclear solid technique is the Mossbauer Spectroscopic technique which has been used to probe the local magnetic properties of a solid. Here we have summarized Mossbauer spectroscopic studies on ferrites.

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.

Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation

2012 ◽  
Vol 733 ◽  
pp. 219-223 ◽  
Author(s):  
P.M.G. Nambissan ◽  
O. Mondal ◽  
C. Chakrabarty ◽  
M. Pal
Keyword(s):  
Positron Annihilation ◽  
Spinel Structure ◽  
Positron Lifetime ◽  
Drastic Change ◽  
Doppler Broadening ◽  
Positron Trapping ◽  
Normal Spinel ◽  
Ni Substitution ◽  
Positron Lifetimes ◽  
Coincidence Doppler Broadening

We report in this work about the inversion of the spinel structure of ZnFe2O4induced by the substitution of Zn2+by Ni2+ions. Positron lifetimes were measured in Zn1-xNixFe2O4with different concentrations (x) of doped Ni2+ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni2+is smaller in size than Zn2+, defects due to non-stoichiometry are less in NiFe2O4than in ZnFe2O4. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.

Positron Annihilation in IR Transmitting GeS2-Ga2S3 Glasses

2015 ◽  
Vol 230 ◽  
pp. 221-227 ◽  
Author(s):  
Halyna Klym ◽  
A. Ingram ◽  
O. Shpotyuk ◽  
R. Szatanik ◽  
E. Petracovschi ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Decisive Role ◽  
Density Variation ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Annihilation Radiation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Positron Trapping ◽  
Trapping Process

Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in GeS2-Ga2S3glasses affected by Ga additions. It is shown that Ga-related void sub-system plays a decisive role in positron trapping process, while the overall density variation is defined mainly by Ge-related sub-system. These results serve as basis for new characterization route for inner free-volume structure of these glasses.

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