Single-Aliquot Regenerative-Dose (SAR) Protocol
Also known as: SAR Protocol, Single-Aliquot Regenerative-Dose OSL, SAR Equivalent-Dose Estimation, Quartz SAR Luminescence
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.
Key highlights
- Corrects for laboratory-induced sensitivity change after every measurement using a fixed test dose, the core reliability gain over earlier methods.
- Yields a complete equivalent-dose estimate from a single small aliquot, conserving sample material.
- Embeds recycling, recuperation, and dose-recovery checks so unreliable aliquots can be objectively rejected.
- Produces many independent dose estimates per sample, enabling statistical detection of partial bleaching or mixing.
Intuition
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How it works
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When to use it
Use the SAR protocol whenever you are estimating the equivalent dose for optically stimulated luminescence dating of quartz, and as the methodological backbone for feldspar and single-grain measurements with appropriate modification. It is the right choice when sediment grains were well bleached by sunlight before burial, when you need many independent dose estimates to assess partial bleaching or mixing, and when material is scarce, since each estimate uses only one small aliquot. The built-in recycling, recuperation, and dose-recovery checks make it especially valuable where signal reliability is uncertain. It is less appropriate without modification for minerals or signals that exhibit strong sensitivity change the test dose cannot track, for grains whose natural signal lies in the saturated, flat region of the growth curve where interpolation is unreliable, or for poorly bleached samples where the dose distribution, not the protocol itself, dominates the uncertainty.
Strengths & limitations
- Corrects for laboratory-induced sensitivity change after every measurement using a fixed test dose, the core reliability gain over earlier methods.
- Yields a complete equivalent-dose estimate from a single small aliquot, conserving sample material.
- Embeds recycling, recuperation, and dose-recovery checks so unreliable aliquots can be objectively rejected.
- Produces many independent dose estimates per sample, enabling statistical detection of partial bleaching or mixing.
- Assumes the test dose faithfully tracks sensitivity change, which can fail for some signals and minerals.
- Interpolation is unreliable when the natural signal approaches saturation on the flat part of the growth curve.
- Determines only the equivalent dose; an accurate age still requires a separately measured environmental dose rate.
- Results depend on appropriate preheat selection, which must be validated with thermal-transfer and dose-recovery tests.
Common pitfalls
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Applications
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Frequently asked
What does 'single-aliquot regenerative-dose' actually mean?
'Single-aliquot' means the whole equivalent-dose estimate is obtained from one small sub-sample (an aliquot) of grains rather than from many separate aliquots. 'Regenerative-dose' means the calibration growth curve is built by giving that same aliquot a series of known laboratory doses and regenerating its luminescence response, instead of adding doses on top of the natural signal. The natural luminescence is then interpolated onto this regenerated curve to find the equivalent dose. Doing everything on one aliquot is efficient and reproducible, but it only works because the protocol also corrects for the sensitivity changes that repeated measurement on one grain would otherwise introduce.
Why is the test dose so important in the SAR protocol?
Because the mineral's sensitivity — how much light it emits per unit of absorbed dose — changes as it is repeatedly heated and stimulated during the measurement sequence. If uncorrected, this drift would make the natural and regenerated signals incomparable and bias the equivalent dose. Murray and Wintle's solution is to follow every luminescence measurement with a fixed test dose and record its response, which serves as a real-time gauge of the grain's current sensitivity. Dividing each signal by its test-dose response cancels the drift, so all measurements lie on a common scale. This normalization is the single feature that made reliable single-aliquot dating possible.
How do you know a SAR result is reliable?
Through the protocol's built-in checks. The recycling-ratio test repeats an earlier regenerative dose and confirms the sensitivity-corrected response is reproduced within roughly ten percent. The recuperation test checks that a zero-dose measurement gives a negligible signal, guarding against charge transfer inflating the result. A dose-recovery test, run separately, gives a bleached aliquot a known laboratory dose and confirms the protocol recovers it. Aliquots that fail these criteria are discarded. Only the equivalent doses from passing aliquots are carried forward, then combined with a statistical age model and an independent dose rate to compute the burial age.
Sources
- 1.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.
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Cite this page
ScholarGate. (2026, June 23). Single-Aliquot Regenerative-Dose (SAR) Protocol. ScholarGate. https://scholargate.app/archaeology/luminescence-dating-sar