Fits one common FWHM value for each peak within a region. This is a proper setting for most regions, where FWHM does not change significantly. The common FWHM setting significantly speeds up fitting, and results in very stable fits.

Fits FWHM individually for each peak within a region. This is rarely selected, when users experience problems due to broadening peaks. Variable FWHM setting significantly slows down fitting, and may result in erroneous fits, because peak width may vary from extremely narrow to extremely wide. However, this is required when one region contains peaks with very different FWHM values, e.g. annihilation peaks with regular ones. The Common peak width method is the default.

Low limit for FWHM for 'Common peak width method'. Relative value to that of calculated from current FWHM calibration.
Default value is 0.7 (FWHM is allowed to variate -30% below the current FWHM value).

High limit for FWHM for 'Common peak width method'. Relative value to that of calculated from current FWHM calibration.
Default value is 1.3 (FWHM is allowed to variate +30% above the current FWHM value).

Low limit for FWHM for 'Variable peak width method'. Relative value to that of calculated from current FWHM calibration. Default value is 0.7 (FWHM is allowed to variate -30% below the current FWHM value).

High limit for FWHM for 'Variable peak width method'. Relative value to that of calculated from current FWHM calibration. Default value is 4.0 (FWHM is allowed to reach 4 times the current FWHM value - for extremely broadened peaks).

Automatically switches to 'Variable peak width method' around the 511.0 keV annihilation peak. Default value is Enabled.

Specifies the energy tolerance relative to 511.0 keV, where automatic switch should take place. Default value is ± 5.0 keV.