Single grain laser luminescence (SGLL) measurements using a novel automated reader

Optically stimulated luminescence (OSL) is used widely for reconstructing past radiation exposure, either in connection with accidental release of radionuclides into the environment, or for dating the time since geological materials were deposited. Measurements of the optically stimulated luminescence properties of crystals are conventionally undertaken on groups of many hundred to many thousand sand-sized (90-300 μm) grains. However, it has long been known that different grains may have different luminescence properties (e.g., sensitivity to dose) and that more information could be gained if single grains could be measured separately, and thus avoid the effect of averaging. Here we describe an automated system that makes the routine measurement of OSL of a large number of single grains feasible for the first time. The concepts underlying the design are described, and initial measurements demonstrate that a reproducibility of 3% can be achieved in repeated OSL measurements of a single grain of Al₂O₃:C. Measurements on a geological quartz sample demonstrate that the system can also analyse natural samples.