LED pulser system for Fermilab's DØ Muon Scintillation counters

Abstract We present the technical design, performance, and stability test results for an LED-based pulser system. The system is used for the Run II Muon Scintillation counters at Fermilab's DO Experiment. Accurate timing information from the scintillation counters is imperative for the proper performance of the muon triggers. The LED Pulser System served in the commissioning of the counters and continues to serve in the monitoring of the performance and the gains of the PMTs. A detailed description of the system is presented, as well as the results of tests on individual components and integrated system. From the test results, the DO LED Pulser System tracks the PMT gains with a precision of 0.2%.