390–410 °C isothermal red thermoluminescence (IRTL) dating of volcanic quartz using the SAR method

We examined basic properties of isothermal red thermoluminescence (IRTL) based on analyses of late Pleistocene volcanic quartz grains. Newly designed apparatus, consisting of a red-sensitive PMT (H7421-40; Hamamatsu Photonics) and a combination of two filters (R60 and IRC-65L), was used to obtain IRTL signals at around 600 nm. Following preheating of the quartz grains at various temperatures, the signal was detected at a rate of 100 ms/gate for 1400 s by holding an aliquot at a fixed temperature of 390 or 410 °C. A heat-down curve (HDC) at a fixed temperature was successfully detected in the preliminary experiments. We also evaluated a high-dose saturation up to 20 kGy, corrected for sensitivity changes.IRTL dating using the single-aliquot regenerative-dose (SAR) method was tentatively applied to the volcanic quartz. Dose-response curves were calculated based on the sum of IRTL signal counts for 1 s (10 gates) at the beginning of the HDC. The obtained IRTL ages, derived from fixed temperatures of 390 and 410 °C, were in the range 112 ± 12–108 ± 10 ka, consistent with the expected age of 112–115 ka.