CRITICAL ANALYSIS OF THE ERROR IN THE EFFICIENCY MEASUREMENT OF GERMANIUM DETECTOR

It is convenient to use a multigamma ray source like Eu-152 for the ca libration of germanium detectors and to make a straight line fitting o f the detection efficiency vs. photon energy on a log-log representati on for the ease in interpolation. Considerable uncertainties are assoc iated with such interpolation as well as the error analysis, particula rly in the energy regions 100-200 KeV and 500-700 KeV, where the depar tures from a straight line are most significant. A more realistic appr oach would be to make a linear plot of a the ratio, epsilon0/epsilon(f ) vs. photon energy, where epsilon(0) and epsilon(f) are the measured and fitted efficiencies for prominent gamma rays of Eu-152. The result ing curve, which magnifies the departures from straight line, allows a more accurate interpolation and error analysis.