title: Defect centres and thermoluminescence in CaSO4:Dy,Ag phosphor.
abstract: The defect centres formed in the TL phosphor CaSO4:Dy,Ag are studied using the technique of Electron Spin Resonance. The Ag co-doped phosphor exhibits three glow peaks around 130, 220 and 375 degrees C in contrast with the two glow peaks observed in the CaSO4:Dy phosphor at 130 and 220 degrees C at a gamma ray dose of 1Gy. ESR studies show that the additional peak at 375 degrees C correlates with a Ag2+ centre formed due to gamma irradiation and observable only below -170 degrees C. The Ag2+ centre is characterised by an axial g-tensor with principal values g(parallel) = 2.38 and g(perpendicular) = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170 degrees C) appears to act as the recombination centre for the TL peak at 375 degrees C; this radical is characterised by the g-values g(parallel) = 2.0023 and g(perpendicular) = 2.0038 and is assigned to SO3- radical. It is observed that there is more incorporation of Ag in the CaSO4:Dy system as compared with that in pure CaSO4 system.
authors.affiliation: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India. bcbhatt2003@yahoo.com
authors.forename: B C
authors.initials: BC
authors.lastname: Bhatt
authors.forename: Bhushan
authors.initials: B
authors.lastname: Dhabekar
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.forename: T K Gundu
authors.initials: TK
authors.lastname: Rao
authors.forename: A R
authors.initials: AR
authors.lastname: Lakshmanan
mesh_terms: D016477:Artifacts; D002133:Calcium Sulfate / Q000737:chemistry* / Q000528:radiation effects*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004307:Dose-Response Relationship, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008422:Materials Testing; D008962:Models, Theoretical; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods
chemical_list: D002133:Calcium Sulfate