scholarly journals Microstructural Investigation of PM-355 Nuclear Track Detector Subjected to Low-Dose Gamma Irradiation: A Positron Annihilation Lifetime Study

2013 ◽  
Vol 04 (10) ◽  
pp. 622-629 ◽  
Author(s):  
Emad Hassan Aly
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Low Dose ◽  
Track Detector ◽  
Nuclear Track Detector ◽  
Microstructural Investigation ◽  
Positron Annihilation Lifetime

The etching and optical response of Tuffak polycarbonate nuclear track detector to gamma irradiation

2009 ◽  
Vol 78 (2) ◽  
pp. 81-84 ◽  
Author(s):  
Jyotsna A. Sapkal ◽  
P.C. Kalsi ◽  
Chhavi Agarwal ◽  
M. Thanamani ◽  
S. Murali
Keyword(s):  
Gamma Irradiation ◽  
Optical Response ◽  
Track Detector ◽  
Nuclear Track Detector

Positron Annihilation Studies in Gamma Irradiated Polyesters

2010 ◽  
Vol 666 ◽  
pp. 75-80 ◽  
Author(s):  
Giovanni Consolati ◽  
Mario Mariani ◽  
Fiorenza Quasso
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Chain Scission ◽  
Polymer Modification ◽  
Scanning Calorimetry ◽  
Positron Annihilation Lifetime ◽  
Combined Action ◽  
Gamma Irradiated ◽  
Crystallinity Changes ◽  
Physical Changes

Polymerisation and polymer modification are often carried out by means of radiation methods, since irradiation can modify the structure of materials and improve their performance. On the other hand, combined action of ionising radiation and oxygen may induce a degradation of the polymer. Physical changes of different polyesters subjected to gamma irradiation up to 1 MGy are discussed and evidenced by various techniques, mainly viscometry, differential scanning calorimetry and positron annihilation lifetime spectroscopy (PALS). Viscometry monitors variations in the molecular weight. Calorimetric measurements allow one to detect crystallinity changes. PALS evidences possible irradiation effects on the free volume; furthermore, it supplies information on the chemical modifications induced by oxygen. The results can be explained in terms of the main mechanisms induced by gamma irradiation (chain scission, crosslinking and oxydative degradation), although their importance depends on the dose.

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.

scholarly journals Positron Annihilation Lifetime Study on free Volume Changes in TLD by Gamma - irradiation

2004 ◽  
Vol 1 (1) ◽  
pp. 144-148
Author(s):  
Baghdad Science Journal
Keyword(s):  
Gamma Irradiation ◽  
Positron Annihilation ◽  
Free Volume ◽  
Volume Fraction ◽  
Gamma Dose ◽  
Volume Changes ◽  
Positron Annihilation Lifetime ◽  
Free Volume Fraction ◽  
First Time ◽  
Free Volume Hole

Positron annihilation lifetime has been utilized for the first time to investigate the free - volume hole properties in thermolumenscent dosimeter ( TLD ) as a function of gamma-dosc . The hole volume, free volume fraction determined form orthopsitronium lifetime are found to be ?lamatically increase to large values , and then to minimum values as a function ofgamma-dose . The free - volume holes size is found to be 0.163nm’ and to have maximum of 0.166nm^ at the gamma-dose of 0.1 and 0.8 Gy, respectively-

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