Characterisation of AGATA Symmetric Prototype Detectors

• Main Author: Dimmock, Matthew Richard
• Published: University of Liverpool 2008
• Subjects: 539.7
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490628

The Advanced GAmma 'Iracking Array (AGATA) is a European project that is aiming to construct a complete 411' High Purity Germanium (HPGe) gamma-ray spectrometer for nuclear structure studies at future Radioactive Ion Beam (RIB) Facilities. The proposed array will utilise digital electronics, Pulse Shape Analysis (PSA) and Gamma-Ray 'Iracking (GRT) algorithms, to overcome the limited efficiencies encountered by current Escape Suppressed Spectrometers (ESS), whilst maintaining the high Peak-to-Tot~l ratio. Iiiji 1.j Two AGATA symmetrical segmented Canberra Eurisys (CE) prototype HPGe detectors have been tested at the University of Liverpool. A highly collimated 137Cs (662keV) beam was raster scanned across each detector and data were collected in both singles and coincidence modes. The charge sensitive preamplifier output pulse shapes from all 37 channels (one for each of the 36 segments and one for the centre contact) were digitised and stored for off-line analysis. The shapes of the real charge and image charge pulses have been studied to give detailed information on the position dependent response of each detector. The singles data has enabled the investigation of the detector response through the bulk crystal. The coincidence data has been utilised to validate the electric field simulation code 11ulti Geometry Simulation (:MGS). The precisely determined 3D interaction positions have allowed the comparison of experimental pulse shapes from single site interactions with those generated by the simulation. The data sets have also been utilised to validate the efficacy of the scanning procedure for producing comparable data sets for consecutive detectors. The absolute position sensitivity has been evaluated.