Extended Data Figure 7 : Example of the red thermoluminescence and pIR-IRSL data for sample LA-1.

From: An early modern human presence in Sumatra 73,000–63,000 years ago

Extended Data Figure 7

a, b, A comparison of the red thermoluminescence signal characteristics using glow curves derived from a Liang Bua sample WR1 (a) and from the Lida Ajer sample (b). The glow curves demonstrate that after 500 Gy dosing the low temperature peaks disappear with the introduction of the 260 °C preheat, and the presence of a light-sensitive shoulder (260–305 °C) that is removed by 1 h of bleaching. The Lida Ajer sample shows similarities with the Liang Bua sample, but has a more defined bleachable shoulder and a more intense signal. c, Isothermal decay of the red thermoluminescence signal from sample LA-1. d, Dose–response curve for the unbleachable signal derived from aliquot A providing a De of 132 ± 13 Gy (see ref. 42 for further methodological details). e, pIR-IRSL intensity and shine down from red-diode stimulation for 250 s at 270 °C, displaying the natural curve and a regenerative dose for comparison. f, pIR-IRSL sensitivity corrected dose–response providing a De of 103 ± 9 Gy. g, The De values of the 22 aliquots of feldspars plotted on a radial plot. Each aliquot was corrected for minor fading and residual dose and was plotted producing an overdispersion of 17.6%. Prior to running the minimum age model a value of 10% was added to the errors as an estimation of inherent overdispersion within the grains. This was determined by estimating the distribution of De values of 12 aliquots after a 4 h bleaching period in a solar simulator. The minimum age model produced a De of 105 ± 3 Gy as depicted by a solid black line, which lies within ±10% of the Central age (shaded box), owing to the low overdispersion. This produces an age estimate of 62 ± 5 kyr. h, Fading tests for the Lida Ajer feldspars comparing the IR50 measurement with a g value of 17.67 with the pIR-IRSL270 measurement, which has reduced the g value to 1.74.