Performance of the trigger system at the HypHI Phase 0 experiment

S. Minami∗1, C. Rappold1,2, S. Bianchin1, O. Borodina1,3, V. Bozkurt1,4, B. Gokuzum1,4, J. Hoffmann1, M. Kavatsyuk5, E. Kim1,6, N. Kurz1, D. Nakajima1,7, W. Ott1, B. Ozel-Tashenov1,4, T. Saito1,3, and W. Trautmann1 1GSI, Darmstadt, Germany; 2IPHC, Universite Louis Pasteur,Strasbourg, France; 3Institut fur Kernphysik, Johannes Gutenberg-Universitat, Mainz, Germany; 4Nigde University, Nigde Turkey; 5KVI, Groningen, The Netherlands; 6Seoul National University, Seoul, Korea; 7The University of Tokyo, Bunkyo, Japan The first experiment of HypHI project, phase 0, has been performed at October 2009 to detect hypernuclei produced by a 2.0 A GeV Li beam impinging on a C target, by identifying the mesonic decay modes, ΛH→He + π−, ΛH →4He + π− and ΛHe →4He + p + π− [1]. A high intensity beam of 10 ∼107 particles per second and a target with a thickness of 8 g/cm were used to overcome small production cross sections expected to be of the order of 0.1 μb. The challenge of the trigger system was to derive a fast trigger signal with a event rate up to 3 kHz under the experimental conditions. Table 1: The conditions for the each trigger, the minimumbias trigger (MBT), the reaction trigger (RT), the hypernuclear trigger(HT) and the He hypernuclear trigger (HeHT). Trigger MBT RT HT HeHT