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2.3.6  Edit Menu

Four data tables in ArArCALC include data necessary for the age calculations, but which you always can edit. These data tables are all located in the Data Tables worksheet and can be selected through the Edit menu. You can also use the F1, F2, F3 and F4 keyboard strokes for faster navigation between these tables.

Procedure Blanks

ArArCALC has been set-up to run on-line during mass spectrometry and by default uses the latest-calculated blank measurement for its blank corrections. However, you can always edit the blank intensities later via the Edit # Procedure Blanks menu item. This function displays a data table containing Blank Intensities and their 1σ Standard Error (SE) for each analysis (step) in your (incremental heating) experiment. You can edit these blank data by clicking the cells and typing in new values. A single click lets you replace the complete number, whereas double-clicking will allow you to edit the number within its cell. To copy values from one cell to another, use the Drag functions of Microsoft Excel (drag the black square anchor visible on the highlighted cell down or to the right) or use the Copy (Ctrl+C) and Paste (Ctrl+P) buttons. Note that you can also copy blank values via the clipboard, in which case you select the cells in which to place your new values and use the Paste (Ctrl+P) button. The Reset button will undo all edits, unless you already have saved them.

You can also select single (or multiple) cells, representing one (or more) analyses, and then choose Import Procedure Blanks from the toolbar. Since ArArCALC saves all blank measurements in text files organized per measurement date, this function allows you to import multiple blank measurements for a range of days, by opening more than one of these text files. Blank measurements can now be selected in the Select Blank Files list box to calculate Average Blanks for all argon isotopes, including their (predicted) standard deviations. This ArArCALC tool then automatically replaces all blank values and uncertainties in the edit table for the selected analyses. However, when the Default Errors checkbox is checked, the standard deviations will be overruled by percentual errors.

You can also click the Advanced Blanks button to analyze the Evolution in the Procedure Blanks over the same range of days. For each argon isotope you can now calculate a linear, parabolic or polynomial fit (pink dashed line). These calculations can be done while generating a standard error or 65-95% confidence envelop (grey dashed lines). The unknowns for which to calculate the blank values are indicated by gray circles at the bottom of the diagram (see also: Import Procedure Blank Toolbox). When you click the OK button, this ArArCALC tool again replaces all blank values and uncertainties in the edit table for the selected analyses.

Intercept Values

You can edit the intercept values via the Edit # Intercept Values menu item. In this data table all Intercept Values including their 1σ Standard Error (SE) are stored together with the r2, the type of line fit (EXP, PAR, LIN or AVE) and the data points excluded from the data regression. Editing is similar as described above. The Reset button will undo all edits.

Sample Parameters

The Sample Parameters (see also: Your First Calculations, Sample Parameters) can be edited via the Edit # Sample Parameters menu. This offers you the possibility to later finalize the actual J-value used in the age calculations or to better define the timing of the measurements. Note that in all the data tables the first two columns on the left (analyses number and increment temperature) cannot be edited. Although there is no possibility (and no need) to edit the analyses numbers, you always can adjust the temperature for each incremental heating step or analysis in the Temp column. All other values can be edited manually. The Reset button will undo all edits.

Irradiation Constants

Finally, the Irradiation Constants may be edited via the Edit # Irradiation Constants menu item. This makes possible the combined age calculation of samples with different irradiation histories (see also: Import Additional Experiments). All irradiation constants can be edited manually. They can also be updated in one go by clicking the Update Irradiation Constants button, which will replace all values with the latest values found in the ArArCALC.log file (see also: Update Irradiation Constants). If you are going to calculate ages in the lunar mode, the labels of this table automatically will be changed from 40/36(a) to 40/36(t) and a default value of 40/36(t) = 1 is assumed (see also: Calculate as Lunar Sample). When you toggle back to the terrestrial age calculation mode, this value gets reset to the default 295.5 value for atmospheric argon. These are the only hard-coded values in ArArCALC and only are applied when toggling to lunar age calculations and back, but you always can overwrite these values by editing the Irradiation Constants table again. The Reset button will undo all edits.