Radiochronology laboratory

Laboratory description

Radiocarbon dating is based on the continuous decay of the radioactive isotope of carbon, ¹⁴C. Radiocarbon is incorporated into all living organisms in proportion to its concentration in the environment. When an organism dies, carbon is no longer incorporated into its tissues, but the radiocarbon present continues to decay at a known rate.

Here at the CEN, we're using the AMS method (Accelerator Mass Spectrometry).

The Pb-210 and Cs-137 datation service is also offered.

1- AMS dating

AMS dating is possible on very small samples (a few milligrams). The CEN has the equipment and expertise to prepare samples for AMS dating, which includes 2 major steps:

Sample preparation by fractionation of their carbon components followed by oxidation and reduction to graphite. The graphite produced is pressed into a target for AMS measurement. Chemical processes are involved in this step.
The counting in a particle accelerator, which involves specialized nuclear physics.

After the samples are received and labelled, we proceed with their chemical pre-treatments.

The next step is combustion, which produces carbon dioxyde (CO₂).

The CO₂ is then purified into a vacuum system.

The resulting ultra-pure carbon dioxyde gas is sealed into a glass tube with a torch.

It is this CO₂ tube that will be shipped to an external laboratory that has an accelerator mass spectrometry facility. This laboratory will convert the CO₂ into graphite, and this graphite will be counted in the accelerator.

For a small additional cost, the IRMS (Isotope Ratio Mass Spectrometry) measurement of the delta ¹³C of your samples can also be done.

With every shipment of many unknown-age samples we must add samples coming from oxalic acid transformation (which is the international standard reference material for all radiocarbon laboratories), inert samples to determine the background value (blanks) as well as known-age samples (secondary standards), coming from multi-laboratory calibration. This procedure assures a never-ending following of the quality, accuracy and precision of the results given to customers.

2- Pb-210 and Cs-137 dating

The CEN radiochronology laboratory also offers Pb-210 dating. It is possible to count the following radionuclides: Pb-210, Cs-137, Am-241, Cd-109, Co-57 as well as Ra-226 (which is the average of Pb-214 and Bi-214) in sediments using the HPGe method (High-Purity Germanium detector).

Sample size requirements (dry samples)

AMS dating

Wood and charcoal:	20 - 80 mg (optimum quantity) 5 mg (minimum quantity)
Shells, carbonates and forams	50 - 60 mg (optimum quantity) 10 - 30 mg (minimum quantity)
Peat, organic matter, seeds, roots:	30 -100 mg (optimum quantity) 6 - 9 mg (minimum quantity)
Organic sediments :	2 - 5 g
Lake sediments:	Please contact us for the possible extraction and datation of humic acids

Pb-210 and Cs-137 dating

All samples:

Usually between 1 g and 3 g (contact us to get the plastic vials which are used for counting)

A bigger quantity is required for samples that are dirty, dusty, sandy or with a high fraction of sediments

P.S. In some cases, it is even possible to date smaller quantities. Feel free to contact us to discuss about your smaller samples.

Submitting samples for datation

¹⁴C

Samples must be dried, clearly identified and packed in plastic (or glass vials), or enveloped in aluminium foil or plastic bags (Ziploc type). Avoid packaging the samples in paper or other organic material.

Please fill the AMS dating form (PDF) (Word) for each sample submitted. Join the form(s) with your package of samples.

Pb-210 & Cs-137

Please contact us to get the plastic vials used in our counter (the transfer of the samples and capping into these vials can also be done by us at the lab). The samples must be dried. Compact the samples as much as you can in the vial and, if possible, try to get a similar height of sample for every vial. Each sample must be weighed with a precision of 0.1 mg.

If you want us to transfer and cap the samples into the plastic vials, please make sure that the samples reach us dried and properly identified. The samples must be packed in plastic vials or plastic bags (Ziploc type).

Fill the Pb-210 dating form (PDF) (Word) for each core (not for each sample) submitted for analysis. Join it with your batch of samples from your core.

The samples must be mailed out to this address:

RADIOCHRONOLOGY LABORATORY
c/o Guillaume Labrecque
Laval University
Abitibi-Price Building, Room 0248
2405, Rue de la Terrasse
Quebec, QC CANADA
G1V 0A6

You'll be contacted via e-mail when your samples reach us at the laboratory.

Price list as of March 1st, 2012 ($ CAN)

	CEN Member Student	CEN Member Professor	UL non CEN and CEN outside UL	External (non-UL) customer

AMS¹	300$	300$	325$	400$


Optional:
IRMS delta ¹³C measurement	40$	40$	40$	40$

AMS (+ humic acids extraction)²	475$	475$	625$	775$


Pb-210 & Cs-137	25$	25$	50$	70$

¹ Including pre-treatments, combustion, CO₂ purification, as well as graphite transformation and AMS analysis by external lab
² Including humic acids extraction from lake sediments or soils, combustion, CO₂ purification, as well as graphite transformation and AMS analysis by external lab

Billing and payment

Submitters from outside Laval University will receive a bill to the address they provided on the dating form after they get their results.

Submitters from Laval University must fill the internal service form, then send it to the unit from where the bill be paid. Your department administration will then send the PO number to us at the laboratory before we can proceed with the analyses.

Contact : Guillaume Labrecque

Room 0248
Abitibi-Price Building
Université Laval
2405 rue de la Terrasse
Québec, Canada
G1V 0A6

Phone : (418) 656-2131 ext. 4486