Daybreak 2200型自动化光释光测量仪的初步定量评估

A primary assessment of a Daybreak 2200 OSL reader using fine grain quartz and CaSO_4:Tm TLD

确认和定量检验释光自动化测量系统的性能指标和系统误差是释光年代学实验室非常重要的一项工作。用细颗粒石英和热释光CaSO_4:Tm剂量片对Daybreak 2200型自动光释光测量仪长时间光激发/辐照对比邻测样的影响以及辐照泄漏、辐照源开关时间作了系统检测。长时间蓝光激发时比邻测样细颗粒石英发生非线性光晒退,激发10ks时其OSL信号损失不大于15%(光强为最大功率的95%),而对更远位置的测样则几乎无影响。机载^(90)Sr/^(90)Yβ放射源在长时间辐照时对比邻测样的影响约为0.02%,对更远位置的样品几乎无影响。Daybreak 2200型测量仪机载β源的快门开关时间约为0.22s(相当于～0.01Gy),β放射源在快门关闭时的泄漏极其微弱,测量时可不予考虑。12个代表性测片位置在测量时具有非常好的一致性,相对标准偏差不超过3%,具有非常低的系统误差。

Daybreak 2200 OSL readers are widely used for luminescence dating applications. As the sample irradiation and illumination may affect discs in adjacent positions, it is critical to confirm that these factors do not introduce significant systematic errors. Effects of cross-irradiation and cross-bleaching were examined and quantified using fine-vain quartz and highly sensitive CaSO4：Tm dosimeters, and the irradiation offset time was measured. The cross-bleaching effect on adjacent aliquots is non-linear with no more than 15% OSL signal reduction following 10ks illumination with the power of blue LED being at 95% maximum. But at positions other than the nearest neighboring sample, almost no effect of cross-bleaching was found. The cross-talk dose, even to the nearest samples, was about 0.2%0 of the applied dose, and it decreased with increasing distance from the source. Offset time of the built-in Beta source shutter is 0.22 s, which can be neglected in regular dating, and leak dose of the source can be ignored as well. Finally, measurement consistency at Position 0. 5, 10,.....and 55 of the sample tray is better than 3% in relative standard deviation.