FWHM calibration concept in HyperLab
In HyperLab, FWHM is a peak width function with the following formula:
and the resulting FWHM value is in channels. This expression depicts a linear dependence between the peaks' channel position (or energy) and their squared width.
To create an FWHM calibration, users first specify several calibration points (channel values with belonging peak widths), and direct HyperLab to perform a least-squares fit to these data points, and determine the offset and slope parameters of the function.
Note: A few HyperLab users argued that this formula is not able to describe the FWHM properly in case of broad energy ranges (e.g. above 5 or 10 MeV). We are investigating this issue, which may result in more complex FWHM function in the future versions.
The FWHM calibration points as well as the fitted parameters are stored in HyperLab databases for each measurement entry. More than one FWHM calibrations may exist in the database for the same measurement, but only the last non-tentative one is treated as the current, valid FWHM calibration, and this will be automatically loaded by the peak evaluator.
The FWHM calibration editor
is used to modify the values of the data points, to add or remove points, or to replace the current calibration with another from the database.