Radiation Hardness of PHENIX Muon Trigger Resistive Plate Chambers

The measurement of quark and anti-quark helicity distributions through parity violating single spin asymmetries in W-production with the PHENIX experiment at RHIC requires new fast muon trigger detectors. PHENIX utilizes Bakelite RPC technology that has been developed for the CMS experiment at LHC. These new detectors will collect data for many years, and it is important to understand the impact the constant radiation exposure in PHENIX will have on the performance of the detectors. Prototype RPCs were exposed to two 0.6 mCi Fe-55 sources that were embedded in the detector gas. The RPC efficiency for cosmic ray detection was measured as a function of the total radiation dose exposure using a cosmic ray tracking detector at UIUC. This poster will discuss the radiation hardness of PHENIX Bakelite RPC prototypes, and how the results compare to the requirements at RHIC.