Facilities
The Geoluminescence Dating Research Laboratory is housed in a refurbished 2000 ft2 facility within the Dept. of Geology at Baylor University. This facility utilizes a variety of luminescence technology including three automated Risø Reader systems The readers have capabilities for thermoluminescence, infrared, blue, and UV stimulation, as well as linear modulation applications. The two automated Risø TL/OSL reader (Bøtter-Jensen 1997) are used for the single aliquot measurements. One Risø TL/OSL reader is dedicated to single grain analysis. Blue light excitation (470 ± 30 nm) is from an array of 30 light-emitting diodes that delivers approximately 25 mW/cm2 to the sample position at 90% power. A Thorn EMI 9235 QA photomultiplier tube coupled with three 3-mm-thick Hoya U-340 detection filters that transmit between 290 and 370 nm will be used to measure photon emissions. Laboratory irradiations used a calibrated 90Sr/90Y beta source coupled with the Risø reader and the experimental sequences were executed using Risø TL/OSL software for MS-Windows. SAR emissions are integrated over the first 0.8 s of stimulation out of 400 s of measurement, with background based on emissions for the last 75- to 100-second interval.
Our library of software provides flexibility to undertake single aliquot or multiple aliquot analyses utilizing regenerative or additive dose procedures. In addition to mounted and calibrated beta source (90Sr) on Risø Reader, the laboratory maintains four independent calibrated, automated alpha and beta irradiators that provide beta or alpha radiation exposure, for up to 20 samples sequentially, at individually prescribed periods ranging from seconds to hours. These sources have been calibrated to standards at the Laboratory for Art History Archaeology at Oxford University, England. A bank of eight automated intelligent alpha counters detect total, slow and fast scintillations. Counters are calibrated with uranium and thorium standards supplied by the U.S. Geological Survey. Gamma and a portion of the beta contribution are calculated from potassium analysis of sediment. A portable Na-I gamma spectrometer is also available for field measurements. The laboratory is illuminated by the indirect and diffuse light from sodium-vapor bulbs (590 nm). The intensity of the light is adjusted to prevent resetting of the OSL signal. This facility is equipped with ultrasonic baths; digital scales and precision preheat plates, IEC 2000 centrifuge, and automated grinders for the preparation of a variety of geological materials for luminescence analysis. This Laboratory has access to electronics laboratory and machine shop within the Physics Department and budgeted amounts for equipment repair or refurbishing.