Data reduction We have developed a Matlab Toolbox for data reduction and error analysis. This allows an efficient and timesaving handling of the comprehensive amount of data aquired during automated measurements. Aquired raw data along with all relevant information necessary for J-value and age calculations, such as irradiation position, irradiation date, sample type, sample name, owner, ...), were brought together in a MySQL database for easy data storage and handling. The MATLAB program (ArAC) directly extracts all relevant information from the database and calculates either space-dependent J-values (for standards) or Ar-Ar ages (for unknowns). Calculated J-values and errors were automatically assigned to the corresponding samples and stored in the database. From airshot measurements, ArAC calculates mass discrimination, and corresponding fractionation factors were stored in the database and automatically assigned to each measurement during J-value or age calculation. ArAC also produces a data output than can easily be used along with the ISOPLOT Excel AdInn provided by the Berkley Geochronology Lab. Implementation of the ArAC software and error analysis is supported by the Geomathematics group at our institute. The whole software package is available upon request. Below a diagram showing the result of individual airshot measurements done on our Faraday-only Argus between January and October 2009. Ratios are renormalized to 295.5 relative to the intraday average. Standard deviation is 0.15%, intraday reproducibility is usually better than 0.05-0.1% dependent on signal size.

J. Pfaender - 2010