Single and multi-grain OSL investigations in the high dose range using coarse quartz. (15th December 2018)

• Record Type: Journal Article
• Authors: Anechitei-Deacu, V.; Timar-Gabor, A.; Thomsen, K.J.; Buylaert, J.-P.; Jain, M.; Bailey, M.; Murray, A.S.
• Is Part Of: Radiation measurements. Volume 120(2019:Jan.)
• Page Start: 124
• Page End: 130
• Publication Date: 2018-12-15
• Subjects: Optically stimulated luminescence (OSL) -- 'Infinitely' old -- Single grains -- Multi-grain aliquots -- Quartz dose response -- Saturation; Nuclear emulsions -- Periodicals; Particle tracks (Nuclear physics) -- Periodicals; Thermoluminescence -- Periodicals; Cosmic rays -- Periodicals; Radiation -- Measurement -- Periodicals; Radiometry -- Periodicals; Radiation Monitoring -- Periodicals; Émulsions nucléaires -- Périodiques; Particules (Physique nucléaire) -- Traces -- Périodiques; Thermoluminescence -- Périodiques; Rayonnement cosmique -- Périodiques; Radiométrie -- Périodiques; 539.77
• DOI: 10.1016/j.radmeas.2018.06.008
• Languages: English
• ISSNs: 1350-4487

Abstract

Abstract: There is evidence that optically stimulated luminescence (OSL) dating of quartz using the single-aliquot regenerative-dose (SAR) protocol underestimates the equivalent dose (De ) for paleodoses above 100–200 Gy. Additionally, 'infinitely' old samples found not to be in laboratory saturation were reported. We present single and multi-grain SAR-OSL investigations for a coarse-grained (180–250 μm) quartz sample extracted from loess collected below the Brunhes/Matuyama transition at the Roksolany site (Ukraine). The sample was dated to more than 1000 ka by electron spin resonance using a multi center approach (Al and Ti signals), confirming that the De (∼2000 Gy) falls beyond the limit of standard OSL De measurement techniques. However, the natural signal measured using multi-grain aliquots of quartz was found to be below the laboratory saturation level. A comparison was made between synthetic dose response curves (DRCs) generated from single-grain and multi-grain aliquot data, respectively; the natural signal was found to be closer to the latoratory saturation level (92%) in the case of the single-grain synthetic DRC than for the multi-grain synthetic DRC where the signal was 86% of the saturation level. This difference could not be attributed to stimulation with different wavelengths, i.e. blue and green light stimulation for multi and single-grain measurements, respectively. By analysing synthetic data obtained by grouping grains according to their brightness, it was observed that brighter grains give a natural signal closer to the laboratory saturation level. This trend was confirmed for multi-grain aliquot data. Based on these findings we infer that variability in the contribution from populations of grains with different levels of brightness may represent a controlling factor in the closeness of the natural signal to laboratory saturation level for infinitely old samples. Highlights: The natural signal of an 'infinitely' old sample is below the laboratory saturation level. Synthetic dose response curves (DRCs) are generated from single-grain and multi-grain aliquot data. The natural signal is closer to saturation for the single-grain synthetic DRC than for the multi-grain synthetic DRC. Brighter grains give a natural signal closer to the laboratory saturation level. A similar trend is also observed for multi-grain aliquot data.