A fully automated multi-spectral radioluminescence reading system for geochronometry and dosimetry

摘要

Following the recent development of a new solid state luminescence dating technique for geochronometry that uses the infrared radiofluorescence (IR-RF) at 1.43 eV (865 nm) of potassium feldspars, an automated radioluminescence (RL) measurement instrument was designed and built. The instrument is based on a commercial Daybreak 1100 automated TL reader system, widely used in thermoluminescence (TL) dating. It was re-designed and highly modified to adapt it to the physical and methodological needs of the IR-RF dating technique and other RL dosimetry applications. This new system holds up to 10 samples, has an integrated bleaching and irradiation unit, and measures the radio-fluorescence (RF) (excitation using 10 ~(137)Cs sources, each 5 MBq activity). All technical requirements for the measurement of optically excited luminescence were implemented in order to investigate the defect structure of luminescent materials. Because of the broad wavelength range and the high sensitivity of the photomultiplier detector used, the system is suitable for a great many luminescent materials, natural and synthetic. This paper summarises the technical features and performance criteria of the system. Furthermore, a calibration method and the dosimetric concepts, using the blue RF emission of Al_2O_3:C at 415 nm for the β source dose rate estimation with low calibation errors is described in detail. Finally, examples of IR-RF dating results on Quaternary sediments together with independent age control are presented.