Charge recombination processes in minerals studied using optically stimulated luminescence and time-resolved exo-electrons

Sumiko Tsukamoto, Andrew Murray, Christina Ankjærgaard, Mayank Jain, Torben Lapp

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    A time-resolved optically stimulated exo-electron (TR-OSE) measurement system has been developed using a Photon Timer attached to a gas-flow semi-proportional pancake electron detector within a Risø TL/OSL reader. The decay rate of the exo-electron emission after the stimulation pulse depends on the probability of (1) escape of electrons into the detector gas from the conduction band by overcoming the work function of the material and (2) thermalization of electrons in the conduction band, and subsequent re-trapping/recombination. Thus, we expect the exo-electron signal to reflect the instantaneous electron concentration in the conduction band. In this study, TR-OSE and time-resolved optically stimulated luminescence (TR-OSL) were measured for the first time using quartz, K-feldspar and NaCl by stimulating the samples using pulsed blue LEDs at different temperatures between 50 and 250 °C after beta irradiation and preheating to 280 °C. The majority of TR-OSE signals from all the samples decayed much faster than TR-OSL signals irrespective of the stimulation temperatures. This suggests that the lifetime of OSL in these dosimeters arises mainly from the relaxation of an excited state of the recombination centre, rather than from residence time of an electron in the conduction band.
    Original languageEnglish
    JournalJournal of Physics D: Applied Physics
    Volume43
    Issue number32
    Pages (from-to)325502
    ISSN0022-3727
    DOIs
    Publication statusPublished - 2010

    Keywords

    • Radiation research and nuclear technologies
    • Radiation physics

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