Implicit <i>FWHM</i> calibration for gamma-ray spectra

FWHM calibration is one of the essential procedures in gamma-ray spectra analysis. Traditional method is time consumption and poor flexibility because of extra measurement on calibration source. This paper introduces an implicit calibration method based on symmetric zero-area conversion. The single peaks can be differentiated from doublets. Meanwhile, the extracted FWHM values can be applied in the fitting process. Various forms of calibration equations are introduced and compared with practical spectrum data under this method.