Freiburg 1999 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 14: Instrumentation und Anwendungen II

HK 14.8: Gruppenbericht

Montag, 22. März 1999, 18:45–19:00, F

Experimental Study of the Influence of Crystal Orientation on Ge Detector Pulse Shapes — •H. Brands, W. Gast, H.M. J"ager, R.M. Lieder, L. Mihailescu, and M. Rossewij — Institut für Kernphysik, Forschungszentrum J"ulich

Detailed investigations of pulse shapes of γ-rays measured with a semihexagonal n-type Ge detector as function of the radius and azimuthal angle have been carried out using collimated γ-sources. The analysis shows a strong anisotropy of the pulse shape as function of angle for a given radius at which the γ-ray interacted with the detector. The angular dependence of the pulse shape is found to correspond to the different mobilities of the charge carriers in the Ge crystal for different directions. The orientation of the crystallographic axes was established by neutron diffraction measurements for the investigated detector. The parameters which characterize the pulse shapes (e.g. time-to-maximum, time-to-steepest-slope or time-to-pulse-end) have a maximum variation of 35% for the crystallographic directions (100) and (111). The results indicate that for pulse-shape analysis the crystallographic orientation of the Ge detector must be taken into account to determine accurately the radius at which a γ-ray interacts with the detector.