40Ar/39Ar Geochronology Software

Since 1998 Prof. Anthony Koppers has been actively working on his freeware ArArCALC software for 40Ar/39Ar geochronology (Koppers 1998).  In 2002 he published the first version (Koppers 2002) that now is used by dozens 40Ar/39Ar laboratories world-wide. Since October 2005 NSF-EAR Instruments and Facilities has been sponsoring the further development of ArArCALC resulting in two major updates. Currently, Prof. Koppers and Dr. Rupert Minnett are designing and programming ArArSUITE which constitutes a new set of software tools for the management of 40Ar/39Ar geochronology experiments and carrying out data acquisitions.


ArArCALC was initially developed at the Laboratory of Isotope Geology of the Free University in Amsterdam as part of the Ph.D. thesis of Anthony Koppers (Koppers 1998). The data reduction software for 40Ar/39Ar geochronology was expanded while he worked at the Scripps Institution of Oceanography in La Jolla. In 2002 the first version was published and became available to the international 40Ar/39Ar community (Koppers 2002) and now is used by dozens of laboratories over the world. Since October 2005 NSF-EAR Instruments and Facilities has been sponsoring the further development of ArArCALC resulting in two major updates. Since his arrival at Oregon State University in 2007, the ArArCALC software has been overhauled to include some long sought-after database functionalities to store J-values, standards run, air shot data, potassium salt, and fluorite data, and include input filters for multi-collector data files.

The program ArArCALC provides an interactive interface for data reduction in 40Ar/39Ar geochronology. ArArCALC is coded within Visual Basic for Excel 2000-XP-2003-2007-2011 using datasheets, charts, menus, and dialog boxes. All 40Ar/39Ar age calculations are reported in single Excel workbooks and thus can be easily shared between different ArArCALC users within and outside laboratories. All workbooks can be saved in various formats (Excel, PDF, XML) and/or using the standard community data format (Renne et al. 2009). Finally, all ArArCALC files and age data can be uploaded to the online data repositories of GEOCRHON and the EarthRef.org Digital Archive (ERDA).

ArArCALC can be used online and offline during mass spectrometry and includes the following basic utilities:

  • Curved or linear data regression
  • Blank evolution analysis
  • Age calculation
  • J-value calculation
  • Air shot calculation
  • Age recalibration

These utilities fully interact with each other providing a high level of automation. ArArCALC also allows for editing of all input data, parameters, and constants used in the calculations at all times. ArArCALC can be run in the new file watch mode that allows auto- and batch-calculation of your mass spectrometer files. ArArCALC now also supports multi-collector files.


As part of the final setup and automation of the new ARGUS VI system a new software is being designed and programmed to allow for the 24/7 automated operation of the CO2 laser, the extraction line valves, and the multi-collector mass spectrometer. The new ArArSUITE software package will allow for:

  • Management of samples, irradiations and sample trays
  • Setup of total fusion, incremental heating and air shot (etc.) experiments
  • Flexible scheduling of multiple already-defined custom experiments
  • On-the-fly editing of heating schedules
  • Data acquisition using the ARGUS VI QTegra C# software environment
  • Generation of text format data files that can be automatically processed by ArArCALC in its file watch mode

The ArArSUITE software package will be made available as freeware similar as ArArCALC.