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Environmental dose rate determination using a passive dosimeter: Techniques and workflow for α-Al2O3:C chips

Kreutzer S., Martin L., Guérin G., Tribolo Ch., Selva P., Mercier N.

Geochronometria

2018

Vol. 45, no. 1

56--67

In situ dosimetry (active, passive dosimeters) provides high accuracy by determining environmental dose rates directly in the field. Passive dosimeters, such as α-Al2O3:C, are of particular interest for sites with desired minimum disturbance (e.g., archaeological sites). Here, we present a comprehensive approach obtaining the environmental cosmic and γ-dose rate using α-Al2O3:C chips. Our procedure consists of (1) homemade field containers, (2) a homemade bleaching box, (3) a rapid measurement sequence and (4) software based on R to process the measurement results. Our validation steps include reproducibility, irradiation time correction, cross-talk evaluation and source calibration. We further simulate the effect of the container against the infinite matrix dose rate, resulting in attenuation of ca. 6%. Our measurement design uses a lexsyg SMART luminescence reader equipped with green LEDs. The irradiation is carried out under the closed β-source. The minimum dose that can be determined was estimated with ca. 10 μGy. However, we also show that for the equipment used, an irradiation time correction of ca. 2.6 s is needed and irradiation cross-talk should be taken into account. The suggested procedure is cross-checked with four reference sites at Clermont-Ferrand showing a good γ-dose rate for three out of the four sites. Finally, an application example, including needed analytical steps, is presented for dosimeters buried at the archaeological site of the Sierra de Atapuerca (Spain).

Performance tests using the Lexsyg luminescence reader

Lomax J., Kreutzer S., Fuchs M.

Geochronometria

2014

Vol. 41, no. 4

327--333

This study presents test measurements on a Lexsyg luminescence reader, acquired by the Giessen luminescence group. The reader is of the type Standard, hence designed for routine determi-nation of palaeodoses using quartz or K-feldspars. The tests include measurements of the stimulation powers, preheat temperatures, OSL- and TL-curves, as well as dose recovery tests and calibration measurements using highly sensitised calibration quartz. A comparison of De values determined using a Lexsyg reader with single grain De -values, which have been previously obtained on a Risø reader, is also presented. The results imply that the Lexsyg reader is a highly reliable measurement device with high reproducibility, yielding instrumental uncertainties of around 0.3%.