10Be - 26Al exposure age calculator

For determining reference production rates from a calibration data set.

Version 2.2. March, 2008. Written by Greg Balco, balcs@bgc.org

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Name for this calibration data set (text only):
Enter calibration measurement data block here.See below for formatting instructions.

Note change in Version 2.2:
Production rates and decay constants have been updated in this version to reflect the Be-10 restandardization and half-life revision in Nishiizumi et al., 2007. Thus, you must now specify the standard to which your Be-10 and Al-26 measurements have been normalized. For a list of currently available standards, see this page.
Notes on developmental version -- current limitations
First, this only uses Be-10 measurements to determine the Be-10 production rate, and then multiplies by the production ratio to obtain an Al-26 production rate. Al-26 measurements are ignored for the time being. Second, this uses an extremely simplified optimization scheme to obtain the best-fitting production rate. This is designed to minimize calls to the time-consuming parts of the exposure age calculation, but it can break if the calibration data set is particularly badly behaved. Third, at present there is no way to deal with artificial target experiments, i.e. zero-age measurements.
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It can take a long time to do the production rate calibration, because each measurement has to be pushed through all of the exposure-age calculation code many times. If the timeout setting on your browser is too short, it will stop waiting for the page before the calculations are done. You can set the wait time to a longer value on some browsers. If that's not true of yours (Safari, for example), you may be out of luck.
Formatting instructions:
This form is designed to have text pasted into it from a text editor or an Excel spreadsheet. The formatting requirements are unforgiving, but easy to follow once you have a spreadsheet set up appropriately. An example spreadsheet of calibration data is here. The rules are as follows:
  1. Enter plain ASCII text only.
  2. Each sample should occupy its own line.
  3. Each line should have seventeen elements, as described below.
  4. Elements should be separated from each other by white space (spaces or tabs).
  5. Something other than white space must be entered for each element. For example, if you have no Al measurements for a sample, you must enter "0" in the Al concentration and Al uncertainty positions.
The seventeen elements are as follows:

  1. Sample name. Any text string not exceeding 24 characters. Sample names may not contain white space or any characters that could be interpreted as delimiters or escape characters, e.g., slashes of both directions, commas, quotes, colons, etc. Stick to letters, numbers, and dashes.
  2. Latitude. Decimal degrees. North latitudes are positive. South latitudes are negative.
  3. Longitude. Decimal degrees. East longitudes are positive. West longitudes are negative.
  4. Elevation/pressure. Meters or hPa, respectively, depending on selection below.
  5. Elevation/pressure flag. Specifies how to treat the elevation/pressure value. This is a three-letter text string. If you have supplied elevations in meters and the standard atmosphere is applicable at your site (locations outside Antarctica), enter "std" here. If you have supplied elevations in meters and your site is in Antarctica, enter "ant" here. If you have entered pressure in hPa, enter "pre" here. Any text other than these three options will be rejected.
  6. Sample thickness. Centimeters.
  7. Sample density. g cm-3.
  8. Shielding correction. Samples with no topographic shielding, enter 1. For shielded sites, enter a number between 0 and 1.
  9. Erosion rate inferred from independent evidence. cm yr-1.
  10. 10Be concentration. Atoms g-1. Standard or scientific notation.
  11. Uncertainty in 10Be concentration. Atoms g-1. Standard or scientific notation.
  12. Name of Be-10 measurement standard. Text. Acceptable values for this parameter are given on this page.
  13. 26Al concentration. Atoms g-1. Standard or scientific notation. Note: at present this does not determine Al-26 production rates. This is here as a placeholder.
  14. Uncertainty in 26Al concentration. Atoms g-1. Standard or scientific notation. Note: as above, this is a placeholder.
  15. Name of Al-26 measurement standard. Text. Acceptable values for this parameter are given on this page. Note: as above, this is a placeholder, but you still have to enter something.
  16. Independently measured exposure age for the site. Years. Note: the code is not yet set up to deal with artificial target measurements, so '0' is not an acceptable input value.
  17. Uncertainty in independently measured exposure age. Years.
Note: Nuclide concentrations should already take account of carrier and process blanks.

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