Changes in natural OSL sensitivity during single aliquot regeneration procedure and their implications for equivalent dose determination
More details
Hide details
Physical Research Laboratory, Navrangpura, Ahmedabad, India
Department of Geography, South Parks Road, Oxford, UK
Online publication date: 2011-06-19
Publication date: 2011-09-01
Geochronometria 2011;38(3):231-241
Measurement of low temperature (90°C–120°C) Thermoluminescence (TL) sensitivity of natural quartz samples subjected to pre-heating and optical stimulation indicate that significant sensitivity changes can occur during measurement of the natural Optically Stimulated Luminescence (OSL). During the measurement of natural signal, the luminescence sensitivity of samples can change by 40%. The sensitivity changes both during the initial preheat and the measurement of natural OSL. The currently used version of Single Aliquot Regeneration (SAR) protocol measures and corrects for the sensitivity changes after preheat and readout of natural OSL. However, it does not take into account the changes in sensitivity during the readout of the natural signal. We therefore developed a correction procedure so that both the natural and the regenerated OSL intensities can be measured and plotted with the same sensitivity and suggest that in the absence of such a correction, a considerable fraction of the SAR based ages could have systematic errors. The correction for the sensitivity is based on the use of sensitivity of 110°C TL quartz peak, which is correlated to OSL signal (Murray and Roberts, 1998). The use of 110°C peak provides a reasonable measure of the changes in OSL sensitivity of quartz. A modified Natural Sensitivity Corrected-SAR (NSC-SAR) procedure, that comprises the measurement of, 1) the TL intensity of 110°C peak for a test dose on sample as received (i.e. natural sample) and, 2) the sensitivity of the 110°C peak of the same sample after the preheat and read out of the natural OSL, is proposed. This ratio, termed as Natural Correction Factor (NCF), then provides a way to correct for sensitivity changes. Results on samples from diverse depositional environments indicated that the NSC-SAR consistently (without exception) provided improved distribution in paleodoses i.e. a lower scatter compared to the standard SAR protocol. In addition, the use of this protocol also resolved anomalous cases where the intensity of natural OSL was significantly above the saturation intensity of the regenerated OSL. Implicitly, this study implies a caution on the use of palaeodoses obtained from single grains as such a correction is not possible in the currently used automated single grain OSL measurement systems. The only way now on will be to analyze aliquots with only a grain on them.
Bailiff IK, Bowman SGE, Mobbs SF and Aitken MJ, 1977. The phototransfer technique and its use in thermoluminescence dating Journal of Electrostatics 3(1–3): 269–280, DOI 10.1016/03043886(77)90099-7.
Duller GAT, 1991. Equivalent dose determination using single aliquots Nuclear Tracks and Radiation Measurements 18(4): 371–378, DOI 10.1016/1359-0189(91)90002-Y.
Duller GAT, 1995. Luminescence dating using single aliquots: Methods and applications Radiation Measurements 24(3): 217–226, DOI 10.1016/1350-4487(95)00150-D.
Duller GAT, 1996. Recent developments in luminescence dating of quaternary sediments Progress in Physical Geography 20(2): 127–145, DOI 10.1177/030913339602000201.
Hansen L, Funder S, Murray AS and Mejdahl V, 1999. Luminescence dating of the last weichselian glacier advance in east greenland Quaternary Science Reviews 18(2): 179–190, DOI 10.1016/S02773791(98)00051-1.
Jain M and Singhvi AK, 2001. Limits to depletion of blue-green light stimulated luminescence in feldspars: Implications for quartz dating Radiation Measurements 33(6): 883–892, DOI 10.1016/S1350-4487(01)00104-4.
Mayya YS, Morthekai P, Murari MK and Singhvi AK, 2006. Towards quantifying beta microdosimetric effects in single-grain quartz dose distribution. Radiation Measurements 41(7–8), 1032–1039, DOI 10.1016/j.radmeas.2006.08.004.
Murari MK, 2008. Component specific luminescence of natural minerals and their application to dosimetry of natural radiation environment. Mohan Lal Sukhadia University, Udaipur, India, unpublished thesis.
Murray AS, 1996. Developments in optically stimulated luminescence and photo-transferred thermoluminescence dating of young sediments: Application to a 2000-year sequence of flood deposits Geochimica et Cosmochimica Acta 60(4): 565–576, DOI 10.1016/0016-7037(95)00418-1.
Murray AS and Mejdahl V, 1999. Comparison of regenerative-dose single-aliquot and multiple-aliquot (SARA) protocols using heated quartz from archaeological sites Quaternary Science Reviews 18(2): 223–229, DOI 10.1016/S0277-3791(98)00055-9.
Murray AS and Roberts RG, 1998. Measurement of the equivalent dose in quartz using a regenerative-dose single-aliquot protocol Radiation Measurements 29(5): 503–515, DOI 10.1016/S1350-4487(98)00044-4.
Murray AS and Wintle AG, 2000. Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol Radiation Measurements 32(1): 57–73, DOI 10.1016/S1350-4487(99)00253-X.
Murray AS, Roberts RG and Wintle AG, 1997. Equivalent dose measurement using a single aliquot of quartz Radiation Measurements 27(2): 171–184, DOI 10.1016/S1350-4487(96)00130-8.
Singhvi AK and Lang A, 1998. Improvements in infrared stimulated dating of partially bleached sediments-the ‘differential’ partial bleach technique. Ancient TL 16: 63–71.
Stokes S, 1992. Optical dating of young (modern) sediment using quartz: Results from a selection depositional environment Quaternary Science Reviews 11(1–2): 153–159, DOI 10.1016/0277-3791(92)90057-F.
Stokes S, 1994a. The timing of OSL sensitivity changes in a natural quartz Radiation Measurements 23(2–3): 601–605, DOI 10.1016/1350-4487(94)90106-6.
Stokes S, 1994b. Optical Dating of selected late Quaternary aeolian sediments from the south western United States. Unpublished D. Phil. thesis. Oxford University.
Strickertsson K and Murray AS, 1999. Optically stimulated luminescence dates for late pleistocene and holocene sediments from Norre Lyngby, northern Jutland, Denmark Quaternary Science Reviews 18(2): 169–178, DOI 10.1016/S0277-3791(98)00050-X.
Wintle AG and Murray AS, 1999. Luminescence sensitivity changes in quartz Radiation Measurements 30(1): 107–118, DOI 10.1016/S1350-4487(98)00096-1.
Wintle AG and Murray AS, 2006. A review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols Radiation Measurements 41(4): 369–391, DOI 10.1016/j.radmeas.2005.11.001.
Journals System - logo
Scroll to top