Covariances between gamma-ray energies

Covariances between experimental data are as significant as variances both in the evaluation of uncertainties and to perform statistical tests. If standard data are used in calibrations, covariances must be taken into account. Covariances are also necessary in order to update values every time when new data are obtained. In this paper we determined covariances between the most important gamma-ray energies for use in Ge-semiconductor detectors calibration recently published by Helmer and van der Leun (Nucl. Instr. Meth. A 450 (2000) 35).