The trigger supervisor of the ARGO-YBJ detector

ARGO-YBJ is a full coverage air shower detector under construction at the Yangbajing Laboratory (4300 m a.s.l., Tibet, People Republic of China). Its main fields of research are gamma ray astronomy and cosmic ray studies. The detector covers /spl sim/5800 m/sup 2/ with single layer Resistive Plate Counters (RPCs), surrounded by a partially instrumented guard ring. This paper describes in detail the ARGO-YBJ Trigger Supervisor, which provides the interface between the Data Acquisition and the Trigger System. It is a simple and robust control instrument that monitors continuously the dead time at different levels in the Data Acquisition architecture. We present in this paper the results of the first pilot runs at the Yangbajing laboratory.