The graph shows the absolute efficiency of an HPGe detector (used for the detection of gamma-radiation). Efficiency is highly dependent on the energy of the gamma-photons. The efficiency has been measured at 46 different energies with the aid of gamma sources (data points with error bars) and a 13-parameter semi-empirical function has been fitted to them (black line). The semi-empirical function consists of partial functions representing the partial effects occurring in the detector, shown by curves in the lower region of the graph. This graph was created by Zsolt Revay, Department of Nuclear Research, Institute of Isotope and Surface Chemistry, Hungarian Academy of Sciences.