The CANDLES trigger system for the study of Double Beta Decay of 48Ca

The CANDLES trigger system is used for the study of Double Beta Decay of
⁴⁸
Ca. The detector of this experiment consists of CaF
₂
crystals as the sources and the detectors, immersed in the liquid scintillator as a 4π active shield. Because the decay constant of liquid scintillator (~a few10ns) is a few ten times shorter than that of CaF
₂
scintillator (~1μs), if we trigger the signal by the pulse height, the energy threshold of liquid scintillator lights are a few ten times lower than CaF
₂
's one. High counting rate of the liquid scintillator causes dead time. In order to avoid this problem, we have developed a Dual Gate Trigger. In this paper, we describe the trigger system of the CANDLES experiment and its performance.