T04_P24

Status report on small sample measurements with ECHoMICADAS AMS facility: 6 years of data processing and statistical results.

Thil F¹, Tisnérat-Laborde N¹, Hatté C^1,2, Noury C¹, Phouybanhdyt B¹

¹Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris Saclay, F-91198, Gif Sur Yvette, France, ²Division of Geochronology and Environmental Sciences, Institute of Physics, Silesian University of Technology, 44-100 Gliwice, Poland

In 2015, a new AMS facility, the ECHoMICADAS was installed in the Laboratoire des Sciences du Climat et de l’Environnement (LSCE) at Gif-sur-Yvette, France. Equipped with a hybrid source, it allows the analysis of solid or gas samples for ¹⁴C measurement. This equipment is completed with several peripheral instruments. For solid measurement, 2 graphitisation systems are used: the homemade Graphitisation line (GéGé) to graphitize CO₂ and an Automated Graphitization Equipment (AGE3) for most of organic samples. For CO₂ gas measurement, the Gas Interface System (GIS) injects a mix of CO₂ and He into the source and allows to couple an elemental analyzer (EA) for organic sample, a tube cracking system for pure CO₂, and more recently a Carbonate Handling System (CHS2) for carbonates or dissolved inorganic carbon.

This presentation focuses on measurement of small samples and how to process raw data. It is based on both CHS2-GIS and EA-GIS examples. We will describe how the data are processed, using a combination of the calculation made in Bats software [a] and of the models which were chosen to consider the constant and the cross contamination [b]. Since 2016, measurements on blanks and standards allow to yield enough statistics to estimate, even before its measurement what will be the age uncertainty, based on several expected parameters: the weight (or quantity of carbon), the current, the sample age, the measurement duration, and the chemical protocol which can induce different contaminations.

[a] Lukas Wacker et al, NIMPR 2010

[b] Salazar et al, NIMPR 2015