Testing the potential of an elevated temperature IRSL signal from K-feldspar

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    Abstract

    Thomsen, K.J., Murray, A.S., Jain, M., Bøtter-Jensen, L. [2008. Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts. Radiat. Meas. 43, 1474–1486] have identified a number of feldspar signals which show significantly less anomalous fading than the conventional IRSL signal stimulated at 50 °C and detected in the blue–violet region of the spectrum. One of these was the post-IR IR signal in which first an IR bleach is carried out at a low temperature (e.g. 100 s at 50 °C) and a remaining IRSL signal is measured at an elevated temperature (100 s at 225 °C; detection in the blue–violet region). It is the latter signal that is of interest in this paper. We test such a post-IR IR dating protocol on K-feldspar extracts from a variety of locations and depositional environments and compare the results with those from the conventional IR at 50 °C protocol. Based on laboratory tests (recycling ratio, recuperation, dose recovery) we show that our SAR protocol is suitable for these samples. The observed post-IR IR fading rates (mean g2days = 1.62 ± 0.06%/decade, n = 24; assuming logarithmic fading) are significantly lower than those measured at 50 °C (mean g2days = 3.23 ± 0.13%/decade, n = 24). The signal is bleachable in nature although residual doses of the order of a few Gy are to be expected. After fading correction the ages are indistinguishable from those measured by IR at 50 °C over an age range from a few ka to >260 ka. However, the correction factor for anomalous fading is only 39% of that of the conventional IR at 50 °C signal. This smaller correction factor makes the new post-IR IR ages much less dependent on the inherent assumptions included in the fading correction model.
    Original languageEnglish
    JournalRadiation Measurements
    Volume44
    Issue number5-6
    Pages (from-to)560-565
    ISSN1350-4487
    DOIs
    Publication statusPublished - 2009
    Event12th International Conference on Luminescence and Electron Spin Resonance Dating - Beijing, China
    Duration: 18 Sep 200822 Sep 2008

    Conference

    Conference12th International Conference on Luminescence and Electron Spin Resonance Dating
    CountryChina
    CityBeijing
    Period18/09/200822/09/2008

    Keywords

    • Radiation physics
    • Nuclear technologies

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