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Forward Upgrades for Resistive Plate Chamber

This presentation discusses the motivation, measurement method, trigger needs, instrumentation, trigger details, and offline analysis challenges of the Resistive Plate Chamber (RPC) for forward upgrades. It also explores the sensitivity and smearing effects of the RPC and highlights the trigger needs and design requirements for the PHENIX collaboration.

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Forward Upgrades for Resistive Plate Chamber

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  1. The Resistive Plate Chamber Forward Upgrades • Outline • Motivation / Measurement Method • Trigger Needs • Instrumentation • Trigger Details • Offline Analysis Challenges Andrew Glenn University of Colorado, Boulder for the PHENIX Collaboration 23rd WWND Feb 14, 2007

  2. Motivation ？ • The sea quark polarizations of the proton can be probed through the single spin asymmetry, AL, of the W+ and W- • The PHENIX collaboration plans to determine AL and σ for W+ and W- bosons at forward and backward rapidities in p+p collisions at 500 GeV. • In a p+p collision, two quarks will interact at two Bjorken momentum fractions (x1 and x2) and produce a W boson. • PHENIX will look at the cases where the W decays to a muon and a neutrino. It will be able to detect the muons but not the neutrino. A.M. Glenn 23rd WWND

  3. Method Details • Using the number of muons detected at forward and backward rapidities, AL can be calculated using: • We could simply compare AL to models but, the sea quark polarizations of the proton can be probedto first orderthrough AL using: Large x2 Large x1 Large x1 Large x2 A.M. Glenn 23rd WWND

  4. Sensitivity • In Bunce et al, Prospects for Spin Physics at RHIC, Annu. Rev. Nucl. Part. Sci. 2000, the sensitivity to the sea quark polarizations were calculated. • The sensitivity is calculated from the number of muons detected as a function x1 and x2. • The Bunce et al. paper, assumes the pT of the W is zero which allows for a one-to-one correlation between measured µ kinematics and the true W kinematics. A.M. Glenn 23rd WWND

  5. Smearing from W pT • Because the neutrino can not be detected, the momentum of the W can not be completely reconstructed from the decay products causing a smearing in the momentum calculated for the W. • Plotting the true x1 value produced in PYTHIA versus the x1 value that would be calculated from the muon, a smearing occurs in the correlation. x from PYTHIA We will continue to study other effects such as going beyond leading order, reconstruction resolutions … x calculated using m A.M. Glenn 23rd WWND

  6. PHENIX Trigger Needs Design Luminosity √s = 500 GeV σ=60mb L = 2x1032/cm2/s Total X-sec rate＝12MHz DAQ LIMIT =1-2kHz（forμarm） Required RF ~ 10,000 Current MuID LL1has a RF of ~500 at 200GeV Abilene Christian University, Brookhaven National Laboratory, University of California, Riverside, CIAE, University of Colorado, Columbia University/Nevis Laboratory, Georgia State University, University of Illinois, Iowa State University, Korea University, Muhlenberg College, Peking University NSF Funded Much of the manpower is DOE funded A.M. Glenn 23rd WWND

  7. ST3 ST2 ST1 RPC 3S RPC 2S RPC 1(a,b)S RPC 1(a,b)N RPC 2N RPC 3N Trigger should provide momentum selection and vertex pointing A.M. Glenn 23rd WWND

  8. Resistive Plate Chambers Altieri, S. Int.J.Mod.Phys.A16S1C:1135-1138,2001 The resistive plate chambers for CMS and their simulation Abbrescia, M. Nucl.Instrum.Meth.A471:55-59,2000 New developments on front end electronics for the CMS Resistive Plate Chambers Abbrescia, M. Nucl.Instrum.Meth.A456:143-149,2000 Single event effect measurements on the resistive plate chambers front end chips for the CMS experiment Abbrescia, M. Temperature and humidity dependence of bulk resistivity of bakelite for resistive plate chambers in CMS Ahn, S.H. Nucl.Instrum.Meth.A451:582-587,2000 Performance of resistive plate chambers for the muon detection at CMS Abbrescia, M. Nucl.Phys.Proc.Suppl.78:90-95,1999 A prototype front end chip for the CMS resistive plate chambers Abbrescia, M. Development of resistive plate chambers for the CMS experiment Vitulo, P. Beam test results on double-gap resistive plate chambers proposed for CMS experiment Abbrescia, M. Nucl.Instrum.Meth.A414:135-148,1998 One quick SPIRES search Endcap resistive plate chambers for the Compact Muon Solenoid experiment Hong, B.S. J.Korean Phys.Soc.48:515-529,2006 Production and quality control of the barrel RPC chambers of the CMS experiment Abbrescia, M. Nucl.Phys.Proc.Suppl.150:290-294,2006 Cosmic ray tests of double-gap resistive plate chambers for the CMS experiment Abbrescia, M. Nucl.Instrum.Meth.A550:116-126,2005 Production and test of one-third of barrel Resistive Plate Chambers of the CMS experiment at LHC Abbrescia, M. Nucl.Instrum.Meth.A535:283-286,2004 The cosmic rays quality test procedure for the CMS barrel resistive plate chambers Abbrescia, M. Nucl.Instrum.Meth.A533:208-213,2004 Aging studies for Resistive Plate Chambers of the CMS muon trigger detector Pugliese, G. Nucl.Instrum.Meth.A515:342-347,2003 CMS barrel resistive plate chambers: Tests and results Pavlov, Borislav ECONF C030626:FRAP07,2003 physics/0309005 Recent experimental results and developments on the resistive plate chambers for the CMS experiment Graphite coating Mylar bakelite Polycarbonate spacer -HV Signal Pick-up GND -HV 0.5cm strips Gas Gas • Good timing performance (~ 1-2 ns) • Good rate capability (~several kHz/cm2) • Space resolution (~ cm ) • Simple design & low cost Typical gas mixture:95%R134A + 4.5% ISO + 0.5% SF6 WE ARE COPYING CMS A.M. Glenn 23rd WWND

  9. Developing Local Expertise Test Stands at multiple institutions GSU Built RPCs A.M. Glenn 23rd WWND

  10. Test Stand Results 0.5cm strips ~5400ft elevation • Strips widths smaller than ~1cm are useless without ADC • No $$ or plans for ADC (with more than one bit) • Cluster distributions needed for trigger simulations A.M. Glenn 23rd WWND

  11. Detector Geometry Match MuTRdead areas RPC3 North RPC2 North MuTR backplate “Rings” of equal  coverage Accessible from tunnel A.M. Glenn 23rd WWND

  12. Readout Strip Geometry RPC2 Octant Units of mm (channels) 141.0 x 11.4 mm Inner RPC1 to 554.2 x 64.6 mm Outer RPC3 Octant and strip readout to be designed to complement MuTR A.M. Glenn 23rd WWND

  13. MuTR FEE Upgrade • Current MuTR Front End Electronics are too slow for Level 1 trigger • New FEE will provide list of hit strips to Level 1 trigger • Current plan is to instrument non-stereo plains in MuTR stations 1 and 2 for both arms • Funding approved by JSPS Riken-BNL Research Center, University of Kyoto, Rikkyo University, KEK, Los Alamos National Lab, University of New Mexico A.M. Glenn 23rd WWND

  14. MuTr FEE Modifications ~1usec AMU ADC MuTr Cathode DCM CPA (3 mV/fC) BBCLL1 GL1 10:90 Split MuIDLL1 New Board 10mV/fC Pseudo-CFD Hit pattern PA FPGA (MuTrLL1) Discri A.M. Glenn 23rd WWND

  15. Trigger Algorithm or RPC1(a+b) RPC2 Candidates found by matching RPC1/2 hits within angular range. Momentum cut made by matching hit in MuTr station 2 within three cathode strips of RPC projection. A.M. Glenn 23rd WWND

  16. Trigger Simulation Results • Full GEANT simulation of PYTHIA events • Use several variations of trigger algorithms (detector combinations) to rejection factors (Statistical errors shown in parenthesis.) • Good efficiency for high pT muons • Based on ~1M PYTHIA p+p events at √s = 500GeV. • Rejection factors are combined for both muon arms. • USES SLIGHTLY DIFFERENT PAD READOUT • All over the rejection goal of 10,000 A.M. Glenn 23rd WWND

  17. Beam-Background Rejection coming from front (in time hits) R1 coming from back (early time hits) R3 R2 • Severity of beam backgrounds at 500GeV (with high luminosity) is largely unknown. • RPC timing used to eliminate early-time hits. • Trigger rejection largely independent of beam-related backgrounds. Collisions! Beam-Related Background A.M. Glenn 23rd WWND

  18. Time Line Absorber may be added in RPC1’s position matching MuTR FEE coverage/timetable. If so, it will be removed or reduced prior to installation in RPC1 a,b A.M. Glenn 23rd WWND

  19. Offline Backgrounds • Triggering on W events is necessary but not sufficient. We should try to address all of the offline background issues we can before taking data • Punch through: Small fraction of high pT hadrons which penetrate through the detector • Fake High pT: Small fraction of low pT hadrons which decay in the MuTR and are incorectly reconstructed with high pT A.M. Glenn 23rd WWND

  20. Punch through Invariant Ed3sigma/dp3 (mb/GeV2) pT (GeV) Red line is UA1 fit form. Magnta & Black: PYTHIA at midrapidity. Blue: PYTHIA at forward rapidity (eta 1.2-2.2). Applying tight matching cuts substantially reduces the background for pions (and kaons) except irreducible fully penetrating category. 10M input 10GeV 20GeV z!=0 background 45k  6k 62k  7k z=0 true punch through 1k  1k 1k  1k z=0 punch + shower 11k  3k 9k  2k Punch through should not be a major issue especially if any absorber is added A.M. Glenn 23rd WWND

  21. Fake High pT Hadron decays in the MuTR can make tracks appear straighter Can be battled with: • Tighter quality cuts / and inter detector matching • Additional absorber (Tungsten from Nose Cone Calorimeter …) • Additional detectors (Forward Silicon Vertex detector) High pT track A.M. Glenn 23rd WWND

  22. Summary • The polarized proton program at RHIC will address two key missing pieces of information through W+/- production: • The antiquark spin structure functions • The PHENIX Forward Upgrade will provide the event selection necessary to access this physics: • New RPC-based tracking chambers • New electronics for MuTr LL1 input • New Level-1 Muon Trigger electronics A.M. Glenn 23rd WWND

  23. Side Note on Heavy Ions • RPCs may provide some reduction of combinatoric background in heavy ion collisions, but the pad sizes are too large to have a dramatic impact • Studies are under way to see if the RPCs can help trigger on dimuons in A+A collisions at RHIC II. A.M. Glenn 23rd WWND

  24. EXTRAS A.M. Glenn 23rd WWND

  25. A.M. Glenn 23rd WWND

  26. Assuming pT of W =0 A.M. Glenn 23rd WWND

  27. f(x, μ2) :The probability of finding a certain parton type (f = u, u, d, d, . . . , g) with positive helicity in a nucleon of positive helicity, minus the probability for finding it with negative helicity Superscripts refer to partons and subscripts to the parent hadron. A.M. Glenn 23rd WWND

  28. Physics Timeline see Spin report to DOE http://spin.riken.bnl.gov/rsc/ L= 1x1031cm-2s-1 6x1031cm-2s-1 1.6x1032cm-2s-1 P= 0.5 0.6 0.7 …………………………………… √s= ……………………….. 200 GeV …………………......... 500 GeV| 2005 2006 2007 2008 2009 …. 2012 (RHIC II) 10 pb-1 …………………………………… 275pb-1 …….. 950pb-1 @ 200GeV @ 500GeV Inclusive hadrons + Jets ~ 25% Transverse Physics Charm Physics direct photons bottom physics W-physics ALL(hadrons, Jets) ALL(charm) AL(W) ALL(γ) A.M. Glenn 23rd WWND

  29. RPC dimensions all units in mm (except theta) strip length and width consider full acceptance in theta and phi in the octants (i.e. no loss due to readout and boxes)strip widths are determined at the outer radius of two paired rings A.M. Glenn 23rd WWND

  30. Trigger Rate and Rejection REAL DATA m momentum dist. At vs=200 GeV PT>10GeV/c HQ signal PT>20GeV/c W signal 25 50 Momentum GeV/c Need Momentum Selectivity in the LVL-1 Trigger! A.M. Glenn 23rd WWND

  31. Existing MuID Level-1 Trigger Logical tubes formed by OR of physical tubes across panels in each gap. Rejection Factor ~500 @ 200 GeV/c The most probable trajectory for a vertex muon striking a gap-1 logical tube is to continue on a path of equal dx/dz (vertical tubes) or dy/dz (horizontal tubes). Tubes w/ the same dx/dz (or dy/dz) get the same index. A.M. Glenn 23rd WWND

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