Thermoluminescence

Abstract: Preface 1. Introduction 2. Theoretical background 3. Thermoluminescence analysis 4. Additional factors governing thermoluminescence 5. Defects and thermolumienscence 6. Thermoluminescence dosimetry (TLD) 7. Thermoluminescence dating 8. Geological applications 9. Instrumentation Appendices References Index.

Abstract: Preface 1. Introduction 2. Theoretical background 3. Thermoluminescence analysis 4. Additional factors governing thermoluminescence 5. Defects and thermolumienscence 6. Thermoluminescence dosimetry (TLD) 7. Thermoluminescence dating 8. Geological applications 9. Instrumentation Appendices References Index.

Abstract: In this text, the authors offer an account of thermoluminescence (TL) and other thermally stimulated phenomena. Although most recent experimental results of TL in different materials are described in some detail, the emphasis is on general processes, and the approach is more theoretical.Thus , the details of the possible processes which can take place during the excitation of the sample, and during its heating, are analyzed. The methods for analyzing TL glow curves are critically discussed, and recommendations as to their application are made. Also discussed are the expected behaviour of these phenomena as functions of the experimental parameters, for example, the dose of excitation. The consequences concerning the main applications of TL (for example, radiation dosimetry) are also discussed in detail as well as the similarities and dissimilarities of other thermally stimulated phenomena, and the simultaneous measurements of the latter and TL.

Abstract: Phosphorescence and thermoluminescence emission from photoconducting impurity activated phosphors have been satisfactorily explained by the storage of electrons, freed from luminescence centres or other atoms of the solid, in metastable energy levels known as electron traps. Electrons escaping from these traps give rise to emission when they recombine with luminescence centres but there is a probability that they may be retrapped in empty electron traps before their final recombination with centres. The present theoretical and experimental studies attempt to determine the extent to which retrapping does occur and what effects it will have in modifying the phosphorescence and thermoluminescence characteristics. Theoretical treatment shows that there are marked differences in these characteristics for conditions when the retrapping process is present and for those when it is negligible. Experimental investigations of the characteristics of specimens of zinc sulphide, zinc silicate and strontium silicate phosphors indicate that, except under special conditions, retrapping of electrons is negligible. These results together with other work can be explained theoretically if it is assumed that electron traps operative in the luminescence process are spatially associated with the immediate neighbourhood of the luminescence centres formed by activating impurities. This new concept is also supported by the relations found between the luminescence characteristics and the dielectric changes in phosphors of the zinc sulphide type.

Abstract: Optically Stimulated Luminescence (OSL) dosimetry is attractive to the health physics and dosimetry community due to its all-optical character, fast data acquisition and the avoidance of heating the detector. Until recently there was no luminescent material sensitive enough to radiation, and at the same time suitable for stimulation with visible light, for use in this application. However, anion-deficient aluminum oxide doped with carbon (Al2O3:C) appears to be not only an extremely sensitive thermoluminescence (TL) material, but is also well-suited to OSL applications. Several OSL readout protocols have been suggested, including cw-OSL, pulsed OSL (POSL), and 'delayed' OSL (DOSL). The paper discusses the physical mechanisms that give rise to the OSL signals and the dependence of these signals upon absorbed dose. Example applications of the use of OSL from Al2O3:C in environmental radiation and ultraviolet-B dosimetry are discussed.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.