Calibration and Trigger Studies for the OSIRIS pre-detector of JUNO

JUNO is a 20 kt liquid scintillator detector under construction in Jiangmen, China, which is expected to start data-taking in 2023. Its main goal is to determine the neutrino mass hierarchy with the measurement of reactor neutrinos from two adjacent nuclear power plants. This requires stringent limits on the radiopurity of the detector. The OSIRIS pre-detector is designed to monitor the liquid scintillator during the several months of filling the large volume of JUNO. OSIRIS will contain 18 ton of scintillator and will be equipped with 76 20-inch PMTs. OSIRIS will utilize two calibration systems: a laser fiber system and an insertion system for an LED or radioactive sources. The data acquisition system will have no global hardware trigger: instead, each PMT will provide a data-stream composed of the digitized PMT pulses, each containing a time stamp. Based on the latter, dedicated event builder software will organize these data streams into events. This talk will discuss the several trigger modes that are realized in the event builder software, a coincidence trigger and the calibration trigger