A Second Level Trigger for HESS Phase 2

Overview & Synopsis

After a very successful start with many sources detected, the second phase of the H.E.S.S. experiment is being implemented. The objective is to build a very large telescope in the center of the array of the 4 existing ones. Operating the very large telescope in coincidence (stereoscopy) with the four H.E.S.S. I telescopes allows to reduce the energy threshold from 100 GeV to 50 GeV. In order to make optimum use of this additional very large telescope and to lower the energy threshold further, one has to consider the single telescope events of this telescope as well. The data acquisition of these events requires a second level trigger for the reduction of the data flow. The concepts for the realization and properties for a second level trigger are presented.