Monitoring environmental dose rate using Riso TL/OSL readers with built-in sources: recommendations for users

Measurements were carried out to quantify the dose rate delivered to samples due to leakage and cross-talk of the beta and alpha sources in various models of Riso TL/OSL readers; additionally the offset time was calculated. Highly sensitive alpha-Al2O3:C and CaF2:Mn dosemeters were used to investigate the impact on low environmental dose-rate assessment. The effect is shown to depend on the energy response of the detectors, the source strength and the reader design of the equipment. It was tested, if the scattered radiation of the closed source can be utilised to extend the dose range downwards to lower doses, as the dose rates of the built-in sources of Riso TL/OSL readers often exceed the practical values for ultra-low-dose measurements. The results and their consequences for environmental dose-rate assessment are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved

Photostimulated luminescence in BaX2 : Eu2+ (X=Br, Cl) X-ray storage phosphors

The photostimulated luminescence (PSL) effect in BaX2 :Eu (2+) (X=Br, Cl) is comparable to that observed in BaFBr:Eu2+ which is used in commercial X-ray storage phosphor screens. After X- irradiation the PSL stimulation spectra of BaX2 :Eu (2+) (X=Br, Cl) single crystals are identical to the F centre absorption spectra, i.e. the F centres are the PSL-active electron trap centres. The nature of the hole centres is still unknown. The PSL response time of about 0.70 mus is within experimental error of 0.02 mus identical to the Eu2+ radiative lifetime, whereas in BaCl2 :Eu2+ the PSL response time is 0.60 mus, and thus longer than the Eu2+ radiative lifetime of 0.47 mus

Developing OSL Geological Dating Techniques for Use on Future Missions to Mars

The surface of Mars has been subject to aeolian, fluvial, and periglacial activity in the (relatively) recent past. Unfortunately, chronological dating of recent events on Mars is difficult as the errors associated with crater counting are comparable to younger ages (approx. 1 Ma). Consequently, techniques to quantify the ages of geological processes on Mars have become an important area of research. Optically stimulated luminescence (OSL) dating is one candidate technique for in-situ dating of the deposition of Martian surface sediments. This method can aid in developing a geological and climatic history of the last million years on Mars. The current paper addresses some of the challenges and progress associated with developing OSL as a viable in-situ dating technique for Mars. Some of the challenges include the mineral composition, the effectiveness of solar resetting under Martian conditions, the temperature regime, and determining the natural dose rate on Mars. All of these topics are currently under investigation, and some preliminary results are presented

Recent advances in dosimetry using the optically stimulated luminescence of Al2O3 : C

This paper presents an overview of some very recent developments in optically stimulated luminescence (OSL) dosimetry using aluminium oxide (Al2O3:C), with special emphasis given to the work of the research group at Oklahoma State University. Some of the advances are: (i) the development of a real-time optical fibre system for in vivo dosimetry applied to radiotherapy; (ii) the development of a fibre dosimetry system for remote detection of radiological contaminants in soil; (iii) the characterisation of Al2O3:C in heavy charged particle fields and the study of ionisation density dependence of the OSL from Al2O3:C; and (iv) fast and separate assessment of beta and gamma components of the natural dose rate in natural sediments. These achievements highlight the versatility of the OSL technique associated with the high-sensitivity of Al2O3:C for the development of new dosimetry applications

Dating techniques: illuminating the past

The technique of optical dating was first reported 30 years ago, and has since revolutionized studies of events that occurred during the past 500,000 years. Here, two practitioners of optical dating assess its impact and consider its future