The PHENIX Muon Trigger Upgrade

The PHENIX muon trigger upgrade adds Level-1 trigger detectors to existing forward muon spectrometers and will enhance the ability of the experiment to pursue a rich program of spin physics in polarized proton collisions at √ s = 500 GeV . The additional muon trigger detectors and Level-1 trigger electronics will allow the experiment to select high momentum muons from the decay of W -bosons and reject both beam-associated and low-momentum collision background, enabling the study of quark and antiquark polarization in the proton. The muon trigger upgrade will add momentum and timing information to the present muon Level-1 trigger, which only makes use of tracking in the PHENIX muon identifier (MuID) panels. Signals from three new resistive plate chambers (RPC’s) and re-instrumented planes in the existing muon tracking (MuTr) chambers will provide momentum and timing information for the new Level-1 trigger. An RPC timing resolution of ∼2ns will permit rejection of beam related backgrounds.