DPG Phi
Verhandlungen
Verhandlungen
DPG

Berlin 2005 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

HK: Physik der Hadronen und Kerne

HK 7: Instrumentation und Anwendungen

HK 7.3: Talk

Friday, March 4, 2005, 15:00–15:15, TU MA042

Charge carrier mobility in segmented large volume HPGe detectors — •B. Bruyneel, P. Reiter, J. Eberth, and D. Weisshaar — IKP, Universität zu Köln

γ-ray tracking in future HPGe arrays like AGATA will rely on pulse shape analysis of multiple γ-interactions. Therefore, an accurate description of electron and hole mobility as a function of the electric field strength is needed. Preamplified signals from a 12-fold segmented MINIBALL detector [1] were processed using digital XIA electronics [2]. For the electrons the whole crystal surface was scanned yielding 336 detector responses with a collimated 241Am source. Anisotropy and crystal geometry cause considerable rise time differences in pulse shapes ranging up to 30% at the front side of the detector. Pulses of direct and transient signals are very well reproduced by weighting field calculations. Exploiting the segmentation a precise measurement of the hole drift anisotropy - a 10% rise time effect - was performed for the first time with 356 keV γ-rays from a 133Ba source. The measured angular dependence of the rise times is caused by the crystal orientation and geometry, changing field strength and space charge effects. For the hole mobility in Ge semiconductors an applicable theoretical description is missing. Hence, a model based on the drifted Maxwellian hole distribution was developed for the hole drift anisotropy using the experimental velocity along the crystal axis as parameters.
∗ Supported by the German BMBF(06 K-167).

[1] P.Reiter et al., Nucl. Phys. A701 209 (2002)

[2] DGF-4C User’s Manual, XIA, http://www.xia.com

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2005 > Berlin