Münster 2017 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 6: Instrumentation I

HK 6.5: Talk

Monday, March 27, 2017, 17:45–18:00, F 072

First performance results of the BGO prototype for the MINIBALL spectrometer — •Dawid Rosiak, Peter Reiter, Jürgen Eberth, Herbert Hess, Iolanda Matea, and Christine LeGalliard — Institut für Kernphysik, Universität zu Köln

The successful HIE-ISOLDE upgrade at CERN with higher beam energies and intensities increases the experimental potential for reaccelerated radioactive ion beams. Direct- and fusion-evaporation reactions will allow access to states at high excitation energies and higher angular-momentum. The existing MINIBALL γ-ray spectrometer was designed for best solid-angle coverage, resulting in high γ-ray efficiency for low-multiplicity events. In order to cope with higher γ-ray multiplicities the MINIBALL triple cluster detectors will be surrounded with BGO Compton-suppression detectors to reject events from scattering of γ radiation between detectors from high energetic γ-rays and multiple hits. After advanced Monte-Carlo studies a BGO prototype was developed and built in collaboration with the IPN Orsay. Mechanical test of the BGO detector as well as for the PMTs and the electronics started in Orsay. A prototype BGO shield was mounted around a MINIBALL triple cluster in Cologne. First results, especially for the crucial Peak-to-total ratio, were obtained from measurements with γ-ray sources.