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2.2.3  Sample Parameters

As an ArArCALC user you have to set the Sample Parameters every time you open a Raw Mass Spectrometry data file (see also: Open Datafile). While you are performing the data regressions for these data, you can always recall this dialogbox via the Options # Sample Parameters menu in order to adjust your settings. The shown fields are always pre-filled with data from the previous calculation, even if these were performed a few days or weeks ago. Completing this dialogbox will be fast, because most entries will be similar and thus don't need changing when regression data from a single (incremental heating) experiment. Most likely, only the GMT datum and Temperature need editing, unless you start to reduce a totally new experiment. If your raw data files already have header lines containing this information, ArArCALC will transfer this header information into this dialogbox by using your Input Filter (see also: Setting the Preferences).

Note   The uncertainties need to be given here as Percent Standard Deviations on the 1σ Level.

Information Panel
It is recommended that you use (as) descriptive (as possible) entries in the Information panel. Fill in sample name and position in the irradiation container in the Sample field, fill in mineral, rock type and grain size fraction in the Material field, and enter full names (instead of initials) in the Analyst field (see also: How to Insert Symbols in Microsoft Excel). In the Location field try to fill in the "true" location name or (if not available) the name of the region or country (in order of preference). Finally, in the Temperature field fill in the incremental heating settings in either °C, laser power in W or laser power in %. Don't enter the units here since you already predefined these in the Input Filter that you used while opening the data file (see also: Preferences). You can always overwrite these default settings by selecting the correct unit from the Options # Heating Unit menu (see also: Heating Unit) when you are in the Age Calculation view.

Correction Factors Panel
In this panel you have to fill in some of the most crucial Correction Factors that are required for the age calculations. First of all, you need to fill in the Standard Age (in Ma) including its proper Standard Name. Next you have to fill in the infamous J-value, the Mass Discrimination Factor (see also: Mass Discrimination Corrections), any needed Volume Correction (if you split your gas sample in any way) and the Sensitivity (in mol/volt). Because you have to provide both a Standard Age and the J-value, this allows ArArCALC to calculate the data either as a flux monitor or as an unknown (see also: Calculate as Flux Monitor).

Resistance on Amplifier Panel
These options are only relevant if you have installed a Variable Resistor on the amplifier, which you can (automatically) switch according to the amount of gas introduced into your mass spectrometer. Select the correct resistance value in order to let ArArCALC normalize the measured intensities to the Default Resistor (109) value. This means that when you select the 108 resistor value that the intensities reported in ArArCALC are 10x higher than measured, and when you select the 107 value that the intensities reported are 100x higher. If you operate with a fixed resistor, you always should keep the default option selected (see example above).

Identifiers Panel
This panel contains two list boxes in which you can select the Irradiation for your sample and under which Project to store the age calculations. Both lists you manage yourself in the Irradiations and Projects dialogboxes and you should make certain that you have entered the appropriate irradiation and project for the sample you are currently processing (see also: Irradiations and Projects).

GMT Datum Panel
You have to set the Inlet Time of the argon gas in the mass spectrometer in this panel. Provide this information as the day (d), month (m), year (y), hour (h) and minute (m) by adjusting the spinner buttons. Although it is preferred that you enter all times in GMT (Greenwich Mean Time), you can also provide local times in this panel. However, in the latter case, you should also make certain that the irradiation times were provided in the same time zone units (see also: Irradiations and Projects) and that you take care of daylights saving time (if applicable in your country). It is highly recommended that you Date and Time Stamp your data files, so that you automatically can read in this information from the header in these files (see also: Configuring the Input Filter).