Commissioning the PHENIX RPC Forward Trigger Upgrade Michael
Daugherity Abilene Christian University for the PHENIX
Collaboration
Slide 2
Physics Motivation Sources of proton spin: : quark contribution
valence quarks, well-known (but surprisingly small) sea quark
contribution has large uncertainties G: gluon contribution being
studied, likely to be small DOE Frontier of Nuclear Science L Z :
Orbital angular momentum, largely unknown
Slide 3
Physics Motivation W-boson production gives nice access to
anti-quark distributions in the proton. 3 A polarized proton
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.
Slide 4
Detecting Forward Ws We take advantage of PHENIXs 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 4 W MuID New trigger Challenges in detecting Ws
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 We need a new high-p t muon trigger to reduce
backgrounds in W signal and maximize data-taking rate. Current muon
trigger provides p t >2 GeV/c background
Slide 5
Resistive Plate Chambers Use established CMS designs of
resistive plate chambers to provide a large area, fast, and
efficient high-p t muon trigger 5 Time resolution 3 ns Average
cluster size~ cm Efficiency 95% Rate capability0.5 kHz/cm 2 Cathode
Anode x = 2mm -10 kV 0 kV W-trigger requirements All requirements
are exceeded with RPC detectors
Slide 6
Forward Upgrade Overview 6 RPC3 (2010) RPC1 (2011) Hadron
Absorber (2010) MuTRG (2008) MuTRG (2009) 2008/2009 Muon Trigger
FEE upgrade RPC3 (2009) 2009 RPC Station 3 North installed 2010
Install RPC Station 3 South and hadron absorber 2011 RPC Station 1
planned install
Slide 7
RPC Station 3 North 7 RPC3 Frame at UIUC RPC3N installation
completed (2009) RPC stations consist of 16 half- octants of three
modules each
Slide 8
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 8 Healthy half-octant module Hit rate
(Hz/cm 2 ) uninstrumented channels Half-octant with dead and hot
channels Entire Station 3N Overall good detector performance, some
issues with gas distribution leading to loss of HV, some dead or
noisy channels to address.
Slide 9
RPC Station 3 South 9 Completed on Sep. 22 Installation
completed about 6 weeks ago, and is being cabled as we speak. (Each
station requires ~ 2 km of signal cable) Significant effort
underway to integrate this station for Run 11.
Slide 10
Hadron Absorber 10 North Hadron Absorber Hadron ( or K)
decaying to muon can produce a fake high-p t track 35 cm of
stainless steel (2 interaction lengths) significantly reduces
background Trade-off between our backgrounds and degrading other
signals (e.g. J/) Absorber severely constrains space for station 1
RPCs
Slide 11
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 11 RPC Station 1 Station 1 Prototype
Slide 12
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 12 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 special thanks to the Forward Trigger
Upgrade Collaboration