Performance Of Germanium Detectors Research Articles

Characterization and performance of germanium detectors with sub-keV sensitivities for neutrino and dark matter experiments

Germanium ionization detectors with sensitivities as low as 100eVee (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues including quenching factors, energy reconstruction and calibration, signal triggering and selection as well as evaluation of their associated efficiencies have to be attended. The efforts and results of a research program to address these challenges are presented.

Preliminary characteristics of a germanium-based, Compton-scatter telescope

The authors have configured a gamma-ray Compton-scatter telescope from five coaxial germanium detectors in order to evaluate the potential performance of germanium detectors in such devices. Due to their excellent energy resolution (0.20% is obtainable at 1.332 MeV), properly configured germanium detectors can produce the best combination of energy and position resolution of any commonly available detector material. The authors present the results of preliminary measurement including energy, position, and timing resolution. The problem of image reconstruction is considered in detail. Design constraints which can affect the overall performance of the telescope are also discussed. >

Monte Carlo simulation of complex germanium detector systems and Compton suppression spectrometers

The performance of germanium detectors and Compton suppression spectrometers is calculated using the Monte Carlo method in the energy range that is of interest for nuclear γ-ray spectroscopy. The calculated properties are: intrinsic peak efficiencies, peak/total and peak/Compton ratios as well as the Compton suppression factor for single γ-rays and high multiplicity γ cascades. The reliability of the calculation is checked by comparison with the observed properties of existing devices. Then, response functions are predicted for new spectrometers. In particular, a new symmetric Compton suppression configuration using three germanium crystals, which is capable of achieving an excellent performance, is proposed. This detector has been constructed and the experimental results are compared with the calculation.

Preparation of Large Volume Planar Germanium Detectors and Results of Their Use in Nuclear Physics Experiments

Improved performance of germanium detectors, prepared by use of lithium-drift techniques, was obtained by means of measurements of diode properties and surface resistivity during preparation. A compensated thickness of 16 mm was obtained for several detectors in a single drift operation. For these and other detectors the provision of a negligible (i.e. < 10?) dead layer on one side allowed the detector to be useful from 10 keV to 10 MeV. An electric field intensity of 50 to 175 volts/mm was sufficient to give satisfactory energy resolution (i.e., 3.0 - 4.5 keV @ 1.333 MeV) and full counting efficiency for detectors of thickness up to 16 mm. The preparation of 2 - 3 cm thick detectors by use of a dual-drift procedure, wherein two adjacent diode structures are caused to merge, is described. The joint use of coaxial and planar techniques, and their relative advantages, are discussed. It is concluded that the preparation of germanium detectors of area 25 cm2 and thickness 1.5 - 3.0 cm is feasible with present techniques, but limited by the quality of the crystals utilized. The results of application of these detectors to muonic x-ray studies, neutron-capture gamma-ray experiments, charged-particle induced reactions involving gamma rays, and isotopic analysis of materials such as uranium are presented. An advantage of a reduction in sensitive volume for some measurements at energies in the range 5 - 10 MeV is shown.