A PEAK-FITTING AND CALIBRATION PROGRAM FOR GE(LI) DETECTORS

A program is described for the analysis of gamma-ray spectra obtained with Ge(Li) spectrometers. To determine the energy and intensity of spectral lines, the region of the pulse height spectrum about each full energy peak is fitted to an analytic function using a least-squares computer code. The basic function used for the peak is the fold of a Gaussian with an exponential (the complementary error function). There are ten parameters in the peak function. Five of these parameters are determined as a function of energy using calibration sources and then held fixed in the fit; only the peak position, area, and the three background parameters are allowed to vary. Multiple peaks are fitted by adding additional parameters for the position and area of each peak. The efficiency calibration of the spectrometer is made using sources with accurately measured relative intensities. There are several advantages to this program over those previously reported: 1) the function used gives a better fit to the experimental peak shape, and 2) unknown sources are fitted with the same function as the calibration sources, so that any differences between the function and the actual peak shape are minimized. Using this program, relative intensities have been measured to better than one percent, and energies to better than 0.1 keV. © 1969.