Dresden 2000 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 13: Postersitzung / Instrumentation und Anwendungen

HK 13.5: Poster

Donnerstag, 23. März 2000, 10:15–12:45, B 117

On-line Pulse Shape Analysis Algorithms for γ-Ray Tracking — •L. Mihailescu, W. Gast, R.M. Lieder, and M.J. Rossewij — Institut für Kernphysik, Forschungszentrum Jülich

A spatial localization and energy determination of multiple Compton scatterings and photoelectric events in a large volume Ge detector is required for tracking and for estimation of the initial direction of the impinging γ-ray. Digital methods for on-line analysis of the current pulses from segmented coaxial HPGe detectors are presented. By a shape analysis of the segment pulses, localization of the interactions can be obtained with a good radial resolution, as well as with an azimuthal resolution superior to that of the segmentation.

Results of new digital methods for signal triggering, as well as for event timing with sub-sampling interval resolution are presented. The digital signal is further processed and transformed into an orthogonal space using Haar wavelets. The complicated spatial distribution of the weighting fields of the segments and the anisotropic conductivity of the Ge crystal create the basis for rather complex pulse shapes. Therefore, a pattern analysis method was developed for the identification of the interaction positions. The employment of highly discriminatory features is the key to a successful recognition system. The Haar transform of the pulse shapes extracts satisfyingly the features characterizing the signal. Another advantage of using Haar transforms consists in an efficient analysis of the pulse shape at a time scale appropriate to the experimental S/N ratio.

Work supported by EU under the TMR contract ERBFMRXCT970123