Real-time digital signal processor implementation of self-calibrating pulse-shape discriminator for high purity germanium

Pulse-shape analysis of the ionization signals from germanium gamma-ray spectrometers is a method for obtaining information that can characterize an event beyond just the total energy deposited in the crystal. However, as typically employed, this method is data-intensive requiring the digitization, transfer, and recording of electronic signals from the spectrometer. A hardware realization of a real-time digital signal processor for implementing a parametric pulse shape is presented. Specifically, a previously developed method for distinguishing between single-site and multi-site gamma-ray interactions is demonstrated in an on-line digital signal processor, compared with the original off-line pulse-shape analysis routine, and shown to have no significant difference. Reduction of the amount of the recorded information per event is shown to translate into higher duty-cycle data acquisition rates while retaining the benefits of additional event characterization from pulse-shape analysis.Comment: Accepted by NIM

Charge Collection Physics in Semiconductor Detectors

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Pulse Shape Discrimination in the IGEX Experiment

The IGEX experiment has been operating enriched germanium detectors in the Canfranc Underground Laboratory (Spain) in a search for the neutrinoless double decay of 76Ge. The implementation of Pulse Shape Discrimination techniques to reduce the radioactive background is described in detail. This analysis has been applied to a fraction of the IGEX data, leading to a rejection of ~60 % of their background, in the region of interest (from 2 to 2.5 MeV), down to ~0.09 c/(keV kg y).Comment: 18 pages, 10 figure

LOW TEMPERATURE MAGNETORESISTANCE AND ELECTRON SPIN RESONANCE IN Ge-Mn-Te

Nous avons mesuré, à basse température, la magnétorésistance, la magnétisation et l'absorption E. S. R. pour un alliage Ge-Te (0,9 at. % Mn) ayant une concentration de porteurs négatifs de 9 x 1020/cc. Il y a corrélation entre la composante négative de la magnétorésistance et le carré de la magnétisation. Cette caractéristique identifie un métal ferromagnétique, à une température inférieure, à la température de Curie. La valeur de saturation de la composante négative de la magnétorésistance augmente pour une diminution de température et peut être reliée à l'intensité du signal E. S. R. pour le même composé.Low temperature measurements of the magnetoresistance, magnetization and E. S. R. absorption are reported for a sample of Ge-Te with a hole concentration of 9 x 1020/cc and containing 0.9 at. % Mn. The magnetoresistance exhibits a negative component which correlates with the square of the experimentally measured magnetization. This behaviour is characteristic of a ferromagnetic metal below the Curie temperature. The saturation value of the negative component of the magnetoresistance increases with decreasing temperature and can be correlated with the E. S. R. line intensity on the same sample

Radiation damage resistance of reverse electrode ge coaxial detectors

Two high-purity germanium coaxial detectors, having opposite electrode configurations from one another, but fabricated from the same germanium crystal, were irradiated simultaneously with fast neutrons from an unmoderated /sup 252/Cf source. Both detectors were 42 mm diam. The detector having the conventional electrode configuration was about 28 times more sensitive to radiaion damage than was the detector havng the p/sup +/ contact on the coaxial periphery. These results prove that germanium coaxial detectors having the conventional electrode configuration should not be used in any situation subject to significant radiaiton damage. This conslusion was anticipated because the defects produced by neutron and proton irradiaiton of germanium act predominantly as hole traps