A Beam Test at SLAC using the LDMX Trigger Scintillator System

The Light Dark Matter eXperiment (LDMX) is a fixed-target missing-momentum experiment aimed at probing the MeV to GeV mass range for dark matter particle candidates. Taking advantage of the higher luminosity that can be provided by the LCLS-II upgrades at SLAC, and a new beamline (Linac to End Station A, or LESA, which is combined with the Sector 30 Transfer Line, or S30XL) to connect with End Station A, LDMX will be able to test several dark matter benchmark hypotheses. Commissioning for the LESA/S30XL beamline has begun at SLAC, and an opportunity has been identified to help with that commissioning using the LDMX trigger scintillator (TS). The TS, as designed, is an ideal instrument for validating the low beam current needed for LDMX to be successful and counting the number of incoming beam electrons per pulse during LESA/S30XL commissioning. This talk will give an overview of the TS, go over the experimental implementation (along with the trigger DAQ system), introduce an online monitoring tool, and summarize the results of this test-beam experiment.