Bonn 2010 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 10: Instrumentierung II

HK 10.1: Talk

Monday, March 15, 2010, 16:30–16:45, HG ÜR 6

FPGA based fast cellular cluster counter and trigger for the Crystal Ball at MAMI — •Peter-Bernd Otte — Institut für Kernphysik, Mainz, Germany

The Crystal Ball (CB) Collaboration at the electron accelerator MAMI in Mainz studies photo-induced reactions on nucleons and nuclei. The new accelerator stage, MAMI-C, delivers high intensity, polarised beams with energies of up to 1.604 GeV. Energy tagged photon beams are produced via Bremsstrahlung using the Glasgow tagging spectrometer. The CB calorimeter is the main part of a hermetic 4π detector system optimised for the detection of multi-photon final states. In conjunction with the TAPS calorimeter, a PID and a MWPC provide further event information.

A new trigger system is presently under construction: it can deal with 1500 digital signals from all detectors and consists of eight FPGA cards of VME size. In the talk, the structure of the setup as well as algorithms employed will be presented and as an example a fast cellular cluster counter for the CB will be explained in detail. Tests of the setup show that the cluster counter decision time is less than 40 ns.