Si ViO: A Trigger for -Particles

AbstractThe production of bound kaon-nucleon-states (kaonic-cluster) in the reaction p + p ![ppK ] + K + should be investigated in adedicated measurement at the FOPI detector system at the SIS-accelerator of GSI, by looking for the decay ppK !p + !p + p + ˇ . To select the final states, the detector system Si ViO has been build up as a trigger for -Hyperons. This detectorconsists of two layers of segmented silicon-strip-detectors, which are able to measure online the particle multiplicity. These twolayers are arranged such, that most of the -Hyperons will decay between them. The trigger signal is generated by comparingonline the hit multiplicity on the two layers.Key words:1. IntroductionIn the last years there have been carried out an extensivelydiscussion about the possible existence of kaonic nuclear states,especially the K pp. This basic kaonic nuclear state was firstpredicted by Akaishi and Yamazaki with a mass of M=2322MeV/c 2 , a binding energy of B K = 48MeV and a width of = 61MeV [1, 2]. The hypothesis has been put forward,that this stats is suggested to be populated quite favorably ina p + p !ppK + K