Large, Multiple Element Germanium Spectrometers

Large coaxial Ge(Li) diodes have been assembled in multiple arrays in one cryostat in order to provide spectrometers of very large sensitive volumes. A double element and a four element spectrometer are described in detail. The latter spectrometer has a total sensitive volume of 180 cm3. The efficiencies and resolutions of the spectrometers were neasured for various combinations of diodes and summing procedures . In the optimium arrangement for the four element spectrometer, a resolution of 15 keV at 1.33 MeV was obtained, and the full energy efficiency was found to be equal to one quarter of that for a 3" × 3" NaI (Tl) scintillation counter. An efficiency curve for the two element spectrometer for energies up to 10 Mev is presented.