Bonn 2010 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 22: Instrumentierung IV

HK 22.5: Talk

Tuesday, March 16, 2010, 15:15–15:30, HG IX

Space charge distribution in AGATA detectors — •Benedikt Birkenbach, Bart Bruyneel, Jürgen Eberth, Herbert Hess, Daniel Lersch, Gheorghe Pascovici, Peter Reiter, and Andreas Wiens — IKP, Universität zu Köln

The Advanced Gamma Tracking Array (AGATA) utilizes pulse shape analysis to localize the γ-ray energy deposition within the 36 segmented high purity Germanium detector. Pulse shape analysis is based on measured or calculated datasets of position dependent γ-ray interactions. The space charge distribution within the n-type HPGe crystals is an essential parameter needed for the calculations. A novel technique, based on a capacitance voltage analysis, was developed to determine the impurity concentration of the large volume detector in three dimensions. The capacitances of the bulk detector and each individual segment were measured as a function of the bias voltage, utilizing the newly developed pulser of the core preamplifier. The results of the method are in good agreement with direct capacitance measurements and results of elaborated computer simulations. The extracted impurity concentrations are about 10¹⁶ atoms per cubic meter. They agree well with the results of analytical approaches and a few data points provided by independent measurements of the crystal manufacturer.

Supported by the German BMBF under contracts 06K-167 and 06KY205I.