Freiburg 1999 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 37: Postersitzung / Instrumentation und Anwendungen II

HK 37.10: Poster

Wednesday, March 24, 1999, 10:15–12:00, Foyer

The Importance of the Anisotropy in the Drift Velocity for the Development of Ge γ-Ray Tracking Detectors — •L. Mihailescu, H. Brands, W. Gast, R.M. Lieder, and M. Rossewij — Institut für Kernphysik, Forschungszentrum J"ulich

In the development of γ-ray tracking detectors the anisotropy of the charge-carrier drift velocity has to be taken into account. The pulse shapes of Ge detector signals depend on the drift velocity of the charge carriers which is highly anisotropic for Ge crystals at the applied operating temperature and electric fields strength. The anisotropic effects result mainly from the anisotropy of two values, viz., (i) the size of the longitudinal component of the charge-carrier drift velocity for different crystallographic directions and (ii) the angle between the drift velocity and the applied electric field.

A method for the estimation of the anisotropy effects and consequently, current density calculations as function of the applied electric field are presented. Results of the implementation of this method in the simulation of the signal shapes produced by Ge detectors of different geometries are shown. Furthermore, different options for the segmentation of Ge detectors and for pulse-shape analysis with the aim of γ-ray tracking are discussed taking into account the anisotropy of the drift velocity.