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Commissioning the PHENIX RPC Forward Trigger Upgrade. Michael Daugherity Abilene Christian University for the PHENIX Collaboration. Physics Motivation. DOE Frontier of Nuclear Science. Sources of proton spin:. ΔΣ : quark contribution valence quarks, well-known (but surprisingly small)
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Commissioning the PHENIX RPC Forward Trigger Upgrade Michael Daugherity Abilene Christian University for the PHENIX Collaboration
Physics Motivation DOE Frontier of Nuclear Science Sources of proton spin: • ΔΣ: quark contribution • valence quarks, well-known (but surprisingly small) • sea quark contribution has large uncertainties ΔG: gluon contribution being studied, likely to be small LZ: Orbital angular momentum, largely unknown
Physics Motivation W-boson production gives nice access to anti-quark distributions in the proton. A polarizedproton experiment is sensitive to the polarization of the sea quarks • A very precise and clean measurement, both theoretically and experimentally. • A “cornerstone” of the RHIC spin program and a DOE milestone for 2013.
Detecting Forward W’s W • We take advantage of PHENIX’s muon arms to look for W decays in the forward/backward region: • compliments PHENIX and STAR W analyses at mid-rapidity using electron/positron decay channel • Challenges in detecting W’s • Cross-section x Luminosity give us an expected interaction rate of 9.6 MHz • DAQ bandwidth for muon arm is 1-2 KHz • Need a rejection power of ~ 10,000 MuID New trigger background • Current muon trigger provides pt>2 GeV/c We need a new high-pt muon trigger to reduce backgrounds in W signal and maximize data-taking rate.
Resistive Plate Chambers Use established CMS designs of resistive plate chambers to provide a large area, fast, and efficient high-pt muon trigger -10 kV Cathode x = 2mm Anode 0 kV W-trigger requirements All requirements are exceeded with RPC detectors
Forward Upgrade Overview RPC3 (2009) RPC3 (2010) MuTRG (2008) MuTRG (2009) Hadron Absorber (2010) RPC1 (2011) • 2008/2009 – Muon Trigger FEE upgrade • 2009 – RPC Station 3 North installed • 2010 – Install RPC Station 3 South and hadron absorber • 2011 – RPC Station 1 planned install
RPC Station 3 North RPC stations consist of 16 half-octants of three modules each RPC3N installation completed (2009) RPC3 Frame at UIUC
Commissioning RPC3N • After Run 10 we sampled cosmic rays to study high momentum tracks in the RPC3N • Each station has (3 modules)*(64 channels/module)*(16 half-octants) = 3,072 channels to evaluate and monitor Entire Station 3N Half-octant with dead and hot channels Healthy half-octant module Hit rate (Hz/cm2) uninstrumented channels Overall good detector performance, some issues with gas distribution leading to loss of HV, some dead or noisy channels to address.
RPC Station 3 South Installation completed about 6 weeks ago, and is being cabled as we speak. (Each station requires ~ 2 km of signal cable) Completed on Sep. 22 Significant effort underway to integrate this station for Run 11.
Hadron Absorber North Hadron Absorber • Hadron (π or K) decaying to muon can produce a fake high-pt track • 35 cm of stainless steel (2 interaction lengths) significantly reduces background • Trade-off between our backgrounds and degrading other signals (e.g. J/ψ) • Absorber severely constrains space for station 1 RPC’s
RPC Station 1 Prototype • With absorbers in place, we have final measurements for station 1 prototypes • Difficult balance between maximizing acceptance and leaving enough room for signal cables, HV/LV, gas, etc. • On schedule to be constructed and installed for Run 12 Station 1 Prototype RPC Station 1
Conclusions • The W measurements are a cornerstone of the RHIC Spin program and an important component of the 500 GeV polarized proton collisions in the next few runs • The Forward Trigger Upgrade is preparing PHENIX to make these important measurements special thanks to the Forward Trigger Upgrade Collaboration • Abilene Christian University • University of California, Riverside • CIAE, Beijing • University of Colorado, Boulder • Columbia University and Nevis Laboratory • Georgia State University • University of Illinois, Urbana • Iowa State University • KEK • Korea University • Kyoto University • Los Alamos National Laboratory • Muhlenberg College • University of New Mexico • Peking University, Beijing • RIKEN Brookhaven Research Center • RIKEN • Rikkyo University