Compare methods

	Single-Aliquot Regenerative-Dose (SAR) Protocol	Potassium-Argon Dating
Field	Archaeology	Archaeology
Family	Process / pipeline	Regression model
Year of origin	2000	1999
Originator	Andrew Murray and Ann Wintle	Developed from 1940s-1950s radiometric work; codified for the 40Ar/39Ar successor by McDougall and Harrison
Type	Measurement protocol for estimating the equivalent dose in optically stimulated luminescence dating	Radiometric dating clock based on radioactive decay of potassium-40 to argon-40
Seminal source	Murray, A. S., & Wintle, A. G. (2000). Luminescence Dating of Quartz Using an Improved Single-Aliquot Regenerative-Dose Protocol. Radiation Measurements, 32(1), 57-73.	McDougall, I., & Harrison, T. M. (1999). Geochronology and Thermochronology by the 40Ar/39Ar Method (2nd ed.). Oxford University Press. ISBN: 9780195109207
Aliases	SAR Protocol, Single-Aliquot Regenerative-Dose OSL, SAR Equivalent-Dose Estimation, Quartz SAR Luminescence	K-Ar Dating, Potassium-Argon Geochronology, K-Ar Radiometric Dating, Potassium-Argon Method
Related	3	3
Summary	The single-aliquot regenerative-dose (SAR) protocol is the measurement methodology that underlies modern optically stimulated luminescence (OSL) dating, providing the recipe by which the equivalent dose of a sediment sample is estimated from a single sub-sample. Its central problem is that exposing a mineral grain to light and radiation in the laboratory changes how brightly it luminesces, so a naive comparison of natural and laboratory signals is biased. Murray and Wintle's protocol solves this by measuring, after every luminescence readout, the response to a fixed small 'test dose' and using it to normalize for sensitivity change, so that natural and regenerated signals can be compared on a common footing. The aliquot's natural signal is then interpolated onto a regeneration growth curve to read off the equivalent dose, and a suite of internal checks — recycling, recuperation, and dose recovery — verifies that the procedure behaved correctly. Because the entire measurement is done on one aliquot, the protocol is efficient, reproducible, and the de facto standard for quartz OSL.	Potassium-argon (K-Ar) dating is a radiometric technique that determines the age of volcanic rocks and minerals from the slow radioactive decay of potassium-40 to argon-40. Potassium is abundant in many rock-forming minerals, and a fixed fraction of its naturally radioactive isotope decays to argon gas at a precisely known rate, so the amount of argon trapped inside a crystal is a clock that starts when the mineral cools below its argon-retention temperature. By measuring how much radiogenic argon has accumulated relative to the remaining potassium, the analyst inverts the decay equation to obtain the time elapsed since crystallization. Because potassium-40 has a half-life of about 1.25 billion years, the method reaches far beyond the radiocarbon range and became the workhorse for dating the volcanic deposits that bracket Plio-Pleistocene hominin fossils at sites such as Olduvai Gorge.