The Helsinki Accelerator Mass Spectrometry facility (HAMS) is the only AMS system in Finland. Most radiocarbon determinations (research and industry) in Finland are done by us. High quality of the results is due to continued process optimization and advanced data-analysis. The sensitivity of the method is currently <10-17 and precision <0.2% for high-precision samples.
Current research topics include:
- Environmental 14CO2 and 14CH4 measurements
- Fuel bioportion measurements
- Climate anomaly (AD 775) research with 14C
- Soil CO2 emission
For potential research ideas or joint projects, don't hesitate to contact us.
For students, we usually have several interesting topics available for a Master's thesis. Be sure to contact us if you want to complete your degree in an interdiciplinary field which also has several connections to the private sector.
Typical samples for 14C measurements are
- Archaeological and geological samples
- Bioportion measurements for gaseous, liquid and solid fuels, flue gases
- Cultural heritage samples from Finland
- Environmental research samples (atmospheric CO2, soil emission CO2, wetland emissions)
Basically any carbonaceous material can be measured for its 14C concentration. Current pricing for an AMS measurement (without any sample pretreatment) is roughly 150€ (VAT 0%) per sample.
All samples are converted to either graphite or CO2 for AMS measurements. So, usually samples are mechically cleaned, chemically treated (e.g. collagen separation, cellulose separation, acid-base-acid treatment), and combusted. The CO2 from combustion is usually converted to graphite and pressed to a small sample holder, after which 39 samples are taken to the AMS ion source.
We have developed a graphitization system for AMS samples. The equipment in use at the Laboratory of Chronology (LoC), Finnish Museum of Natural History.
LoC handles the sample preparation for HAMS as part of the Radiocarbon Analytics Finland (RACAF) organization:
We have developed a ﬁeld-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional ﬂask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce signiﬁcant under-pressures or signiﬁcant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a signiﬁcantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in-situ estimation of the amount of collected CO2 and the determination of CO2 ﬂux to a chamber.
A similar sampling system for CH4 has been developed and a report submitted for publication.
In addition to the measurement of normal solid graphite samples (made from solid, liquid or gaseous carbon samples), one of our ion sources can measure the 14C from CO2 gas directly. This sidesteps several hours of samples preparation and enables the measurement of much smaller samples (down to 10 micrograms of carbon).
The Bayesian CAR (continuous autoregressive) model for accelerator mass spectrometry (AMS) data analysis delivers uncertainties with less scatter and bias. Better detection and estimation of the instrumental error of the AMS machine are also achieved.