The Effect of Exposure to Various Gaseous Environments on the Subsequent Performance of High Purity Germanium Gamma Ray Detectors

Prior exposure to certain gases appears to largely determine the subsequent performance at LN2 temperatures of high purity germanium detectors with exposure temperature being a critical factor. These gases are hydrogen, water vapor and possibly oxygen. An optimum concentration of water vapor in the environment to which the detectors are exposed prior to cool down appears to be essential to achieving good performance and stable operating characteristics.