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.
Is your browser timing out before receiving the results?
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.
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:
The seventeen elements are as follows:
- Enter plain ASCII text only.
- Each sample should occupy its own line.
- Each line should
have seventeen elements, as described below.
should be separated from each other by white space (spaces or
- 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.
Note: Nuclide concentrations should already take account of carrier and process blanks.
- 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.
- Latitude. Decimal degrees. North latitudes are positive. South latitudes are negative.
- Longitude. Decimal degrees. East longitudes are positive. West longitudes are negative.
- Elevation/pressure. Meters or hPa, respectively, depending
on selection below.
- 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.
- Sample thickness. Centimeters.
- Sample density. g cm-3.
- Shielding correction. Samples with no topographic shielding, enter 1.
For shielded sites, enter a number between 0 and 1.
- Erosion rate inferred from independent evidence. cm
- 10Be concentration. Atoms g-1. Standard or scientific
- Uncertainty in 10Be concentration. Atoms g-1. Standard or scientific
- Name of Be-10 measurement standard. Text. Acceptable values for this parameter are given on
- 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.
- Uncertainty in 26Al concentration. Atoms g-1. Standard or scientific
notation. Note: as above, this is a placeholder.
- 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.
- 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.
- Uncertainty in independently measured exposure age. Years.