Run II Upgrade of the ATLAS MBTS

1 Introduction The Minimum Bias Trigger Scintillators, or MBTS, serve as a low-pT cut trigger in the ATLAS detector, covering a pseudo-rapidity range of 2:08 3:86. Originally designed primarily for low luminosity runs alone, the MBTS performed better than expected, and the decision was made to keep the system for Run II, with some alterations. Modications include the replacement of the scintillator disk due to radiation damage, merging of outer- radius scintillating panels (due to limited availability of PMTs), the use of dierent PMTs than in Run 1, and the use of constant fraction discriminators to replace the former leadingedge discriminators. I primarily performed hardware tests to check for correct installation and to reasonably determine the maximum rate at which the MBTS will be able to trigger for upcoming Run II low-luminosity LHC lls.