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Title: Characterisation of an asymmetric AGATA detector
Author: Unsworth, Carl David
ISNI:       0000 0004 2736 7785
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2011
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The Advanced GAmma Tracking Array, AGATA, is a European project aimed at constructing a next-generation gamma-ray spectrometer for nuclear structure studies. The completed array will consist of a 47f shell of 180 highly segmented HPGe detectors arranged into 60 triple clusters. The array will be instrumented with state of the art digital electronics, and will apply Pulse Shape Analysis (PSA) and Gamma-Ray Tracking (GRT) algorithms to achieve high efficiency while maintaining the excellent peak-to-total ratio of current escape-suppressed spectrometers. Vital to the successful application of PSA is the establishment of a pulse shape database describing the signal shape produced by interactions at each point in the detectors volume. Electric field simulations have been developed within the AGATA collaboration to provide this signal basis but it is necessary that they are tested against experimental measurements. Characterisation measurements were performed on asymmetric AGATA capsule C00l using the Liverpool scanning system and state-of-the-art digital electronics. A highly collimated beam of 662ke V gamma rays was scanned across the detector and single and coincident trigger modes were used to measure the response due to gamma rays interacting at precisely determined points within the detector. These signals were then compared with signals produced by the electric field simulations Multi Geometry Simulation (MGS) and JAVA AGATA Signal Simulation (JASS) and an assessment made of their performance. Position resolutions of 7.8mm and 8.4mm have been measured when performing PSA with MGS and JASS respectively. These values are larger than expected and an attempt has been made to understand the reasons for this. In addition, measurements have been carried out to assess the electronics response function of the detector and associated electronics. The results of these characterisation measurements will be used by the AGATA collaboaration to refine the online PSA and GRT algorithms used with the array.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral