2023 Departmental Poster Competition

The Light Dark Matter eXperiment (LDMX) focuses on the detection of light dark matter particles in the sub-GeV mass range. It is based on generating dark matter particles by dark bremsstrahlung of electron beams scattered by a fixed tungsten target. Because dark matter does not participate in electromagnetic interactions, it passes undetected through the tracker and calorimeters. Thus, evidence of dark matter can be found by analysing missing energy (or momentum) distributions of the scattered electrons. The energy of these scattered electrons can be measured by the electromagnetic calorimeter (ECAL), and one can measure the incident energy by counting the number of electrons hitting the target. The LDMX Trigger Scintillator (TS) module is designed using Silicon PhotoMultipliers (SiPM) made of plastic or LYSO to rapidly count the number of electrons (minimum ionizing particles (MIPS)) in the incident beam pulses of fixed, known energy. It is important for the scintillators to accurately count these electrons for effective triggering of signal events and rejection of background events. In this project, we summarize the performance of a prototype TS module based on a three-week test beam experiment performed in April 2022 using different beam configurations. By carefully analysing the integrated output charge distributions, we measured different performance parameters like SiPM gains, pedestals and the system's response to MIPs. Over the period of the test beam experiment, we observed the module having a large response to MIPs and stability of the SiPM performance parameters.