SiViO: A trigger for -Hyperons

The production of bound kaon–nucleon-states (kaonic-cluster) in the reaction p + p → [ ppK - ] + K + should be investigated in a dedicated measurement at the FOPI detector system at the SIS-accelerator of GSI, by looking for the decay [ ppK - ] → p + Λ → p + p + π - . To select the final states, the detector system Si Λ ViO has been build up as a trigger for Λ -Hyperons. This detector consists of two layers of segmented silicon-strip-detectors, which are able to measure online the particle multiplicity. These two layers are arranged such, that most of the Λ -Hyperons will decay between them. The trigger signal is generated by comparing online the hit multiplicity on the two layers.