HPGe_resvbias

FWHM resolution for the Cs-137 peak improves as the bias voltage is raised. Some cycling and some continued vacuum pumping of the Dewar have improved the resolution slightly since this measurement; it now stands at about 0.23% FWHM @ 662 keV, with bias at +2600V. Increasing noise becomes evident at 3000V, so I limit the voltage below this. Unlike photomultiplier tubes, the pulse height changes little with changing voltage except at the very lowest voltages (<100V).