RPCs in the PHENIX Muon Trigger What are RPCs ? Required rejection and what can be obtained from dedicated level 1 trigger trackers Beam related backgrounds Pattern recognition RLT The CMS RPCs Plans for 2004 Matthias Grosse Perdekamp, RBRC and UIUC

Basics of Resistive Plate Chamber From Yong Ban Basics of Resistive Plate Chamber The chamber structure: Gap: 2 mm; HV electrodes : 100 m graphite Gas pressure : ~ 1 Atm Gas mixture: ~ 95% F134a, ~ 4.5% Iso-Butane, 0.5%SF6; bakelite resistivity 10 10- 10 12 cm The signal is induced on the read-out electrodes.

Basics of Resistive Plate Chamber: working mode From Yong Ban Basics of Resistive Plate Chamber: working mode Avalanche: The electric field is such that the electron energy is larger than the ionising potential The separation avalanche-streamer decreases with increasing HV . CMS-RPC will work at avalanche mode, to ensure the proper operation at very high rate. RPC has been used in L3, ARGO-YBJ,Belle, BaBar experiments. all 4 LHC experiments will use RPC for muon system.

Interest in the Muon Trigger Brookhaven National Laboratory: Edward Kistenev, Peter Kroon, Mike Tannenbaum, Craig Woody University of Colorado Frank Ellinghaus, Ed Kinney, Jamie Nagle, Joseph Seele, Matt Wysocki University of California at Riverside Ken Barish, Stefan Bathe, Vasily Dzhordzhadze, Tim Hester, Xinhua Li, Astrid Morreale, Richard Seto, Alexander Solin University of Illinois at Urbana Champaign Mickey Chiu, Matthias Grosse Perdekamp, Hiro Hiejima, Cody McCain, Jen-Chieh Peng, Ralf Seidel Iowa State University John Lajoie, John Hill, Gary Sleege Kyoto University Kazuya Aoki, Ken-ichi Imai, Naohito Saito, Kohei Shoji Moscow State University Mikhail Merkin, Alexander Voronin Nevis Laboratory Cheng Yi Chi Peking University Yong Ban, Yajun Mao, Ye’ Yanlin University of New Mexico Doug Fields RIKEN Atsushi Taketani RBRC Gerry Bunce, Wei Xie University of Tennesee Ken Read, Soren Soerensen INFN Trieste Andrea Vacchi, Mirko Boboesio, Gianluigi Sampa Group with re-newed interest in PHENIX with the possible addition some members of the CMS muon trigger group at Peking University.

Muon Trigger Rates in Run 2003 at 200 GeV At √s=500GeV, L=2x1032cm-2s-1: Collision related: o decay-muon and hadron punch thru background rate > 30kHz  Reject with momentum cut o “remanent induced showers”  shielding, pointing, radial cuts Beam related backgrounds: o hadron punch thru o neutrons o decay muons with incoming beam or outgoing beam Wei Xie rejected with timing cut in time but have to punch through all of PHENIX

What has been simulated? I Wei Xie Upgraded muon trigger Add dedicated muon trigger detectors up- and downstream of the muon tracker magnet. Need robustness against beam and collision related backgrounds. Support muon tracking New trackers Nose cone calorimeter (NCC) Can the NCC be used to improve the W-identifcation off-line? - Is this necessary?? similar in the south arm!

What has been simulated? II Current muon trigger: 2.3GeV “deep” muon Factor of 20-50 rejection and robustness to background required for p+p at highest luminosities W Z bottom charm Two new tracking chambers add momentum information to trigger. RPC’s are the solution for downstream tracker Even modest timing information help remove beam related background. Upstream: RPC or upgrade muTR front end with output to LL1 Detailed simulations with lookup-table algorithms give specifications: Upstream tracker granularity 10x10cm2 into look-up table Downstream tracker granularity 30x30cm2 into look-up table f resolution = 1o RPC R&D at UIUC and prototype for run 5. Build on CMS experience?

Muon trigger rejections LUT for tile size: 10cm upstream, 30cm, downstream Trigger: (UT*DT*muID.LL1)match*angle-cut

Results on Rejection Factors (see Wei’s talk for details) (1). MuTr#1. PC2 Res(R)=10cm, Res(phi)=1o. Mutr#1 tile size 25cm/PC2 tile size 60cm () degree <1 <2 <3 <4 <5 <6 <7 <8 <9 <10 eff 67% 72% 73% 74% rej 24286 15455 10000 7391 6071 5484 4250 3864 3091 1518 (2). MuTr#1. PC2 Res(R)=20cm, Res(phi)=1o. Mutr#1 tile size 25cm/PC2 tile size 60cm () degree <1 <2 <3 <4 <5 <6 <7 <8 <9 <inf eff 58% 63% 64% 64 % rej 24286 17000 11333 8500 6800 6296 5152 4857 3778 1735 PISA hits is smeared in R/. Need to re-do using real detector configuration. efficiency for MuTr/PC2/symset LUT is only 76%. Need to understand. efficiency for angle cut <1 degree is less since the PC2 angular resolution is 1 degree. Efficiency for LUT start to drop after PC2 resolution > 10cm.

Beam related backgrounds: RPC timing resolution! Scintillator Pair Three beam background components: Incoming beam background (out of time) Outgoing beam background (attenuated by PHENIX absorber) Neutron background (out of time) Scintillator study of background time structure in run 2004 (Wei Xie)

Beam Background simulations New PHENIX Experiment Specific Shielding – (final configuration in progress) Typical Background iron 4’ thick, 10.5' tall Plan View Elevation View Vasily Dzhordzhadze Blue beam Yellow beam MuID MuID

- + p  + - e+ e- n Particles reached MuID Gap 5 absorber 10K 100 GeV protons incident on Q03 Integrated overall Energies

100K Incident Protons scrapping Magnet GAP 5 MARS Study shows that Shielding will reduce background only by factor of 3-4

Pattern Recognition for Muon Tracking? David Slivermyr, Vince Cianciolo Muon trigger Upstream tracker (pad chamber or RPC) Downstream tracker I (pad chamber or RPC) Downstream tracker II with timing resolution (RPC) Muon from hadron decays Silicon endcap Muon from W U-Tracker D-I-Tracker Utilize and upgrade (LL1 output) existing pad- chamber front end electronics (90k channels) pad-size upstream: 1cm2 downstream: 10 cm2 D-II-Tracker

R&D and test data Evaluation of muID LL1 Wei Xie, Ken Barish: using run 03 data (UCR) Background Hiroki Sato: run 02 (Kyoto) Ken Read, Vasily Dzhordzahdze, Vince Cianciolo: run 03, run04 (UT, ORNL) Wei Xie, Hiro Hiejima, MGP (RBRC, UIUC) Cherenkov Kazuya Aoki, Naohito Saito, Atsushi Taketani: run 03 (Kyoto, RIKEN) Nosecone Mikhail Merkin, Edward Kistenev, Richard Seto, Gianluigi Sampa (MSU, BNL, UCR, INFN Trieste) MuTr Kazuya Aoki, Hiroki Sato, Naohito Saito, Doug Fields (Kyoto, UNM) RLT/RPC Hiro Hiejima, Alex Linden Levy, Cody McCain, Jen-Chieh Peng, Joshua Rubin, Wei Xie, Matthias Grosse Perdekamp (UIUC, RBRC) Matthias Grosse Perdekamp, RBRC and UIUC

Introduce RPC technology: RPC o The relative luminosity analysis requires two luminosity monitors which can be scaled to high rates. o ZDC is fine but BBC and NTC have large acceptance and will saturate At L=2x1032cm-2s-1 we expect on average 1.2 interactions/bunch-crossing! RLT : New 3-station telescope located vertically above the interaction region. o longitudinal segmentation with ability to a) reject (to a certain degree) non-vertex related background b) monitor luminosity for different vertex cuts. o azimuthal segmentation to select different momenta and to scale acceptance with luminosity.

Introduce RPC technolgoy: RLT x MA-PMT x Technology: RPC vs Scinitillators? x x x x FEM LL1 LUT corresponding to different vertex cuts and pT bins. 80cm nosecone HBD/TPC/Silicon STAR-Scalers

RLT test during run 04 Analysis ongoing, RPC tests at UIUC

CMS-RPC Project: RPC system at CMS detector From Yong Ban CMS-RPC Project: RPC system at CMS detector The first level trigger should ensure: 1.Complete coverage of the solid angle 2. Robustness: maximal use of available information 3. Speed: decision time of the order of 1 muon s (Letter of intent CERN-LHCC 92-3 1 Oct. 1992) China’s share of task: RE1/2, RE1/3 of end-cap RPC (totally 144 detectors); RB1(in,out) of Barrel RPC (totally 120 detectors);

Cosmic ray test of the RPC prototype at Peking University From Yong Ban Cosmic ray test of the RPC prototype at Peking University avalance signal cosmic rays trigger. Streamer signal The RPC prototype was being tested by cosmic rays: 3 layers of scintillator construct the cosmic-ray telescope. s small percentage of SF6 killed the streamer signal .

Beam test of Chinese RPC prototype at GIF of CERN From Yong Ban Beam test of Chinese RPC prototype at GIF of CERN GIF(Gamma Irradiation Facility): simulate the irradiation environment at LHC. Chinese RPC prototype was being tested at GIF

Beam test results of Chinese RPC prototype From Yong Ban Beam test results of Chinese RPC prototype Conclusion: The Chinese RPC prototype has good mechanical strength,gas-tightness and HV performances; The efficiency and time resolution are satisfactory; The efficiency at very high irradiation is limited due to the high resistivity of the bakelite. The PKU-RPC group accumulated experience and technical know-how of RPC.

Laboratory construction at PKU From Yong Ban Laboratory construction at PKU Build laboratory for RPC R&D, assembly and test (shared by nuclear experiment group): area of the hall of the workshop ~150m2.

Goals and Schedule for 2004 o RLT background tests  analysis ongoing o RLT as test bench for RPCs and front end electronics  test stand at UIUC  obtained first RPC prototype from Tsinghua U. o Tap into Peking experience with CMS trigger chambers.  complete performance evaluation available.  evaluate to what extend the CMS design can be adapted for PHENIX.  noise rate?  Front end electronics? o Independent of technology: production in China, NuTech (STAR TOF RPCs, excellent company!!). o RPC FEEs ??

Summary RPCs are well explored cheap technology for muon trigger applications at the LHC. Good timing resolution will proof efficient in rejection incoming beam backgrounds and neutrons. Potential to support the muon tracking. Possibility to build on CMS experience through the Peking group. RLT may serve as first step in mastering technology locally.

Muon Trigger: Physics Motivation pp dA AA A-dependence of nucleon structure Quark polarizations -Spectroscopy Measure the A-dependence of the gluon distribution at small x: o Drell Yan o Heavy flavors  does this require a muon trigger upgrade? / Flavor separation of quark and anti- quark polarizations in W-production: Study color screening effects associated with QGP production in quarkonia with different binding energies. RHIC II luminosities in combination with beam backgrounds may require level 1 trigger. ΔG to small x: measure ∫ ΔG(x)dx? Open Heavy Flavor? What is the impact of high statistics measurements of ALL in open heavy flavor production at 500 GeV on ∆G at small x. Is there anything the trigger Upgrade can add to doing this in the “e-mu-coincidence” channel… Precision study of heavy quark energy loss and fragmentation in the final state formed in HI collisions at RHIC.

The Importance of x-coverage  uncertainty in low-x extrapolation! Example: Measuring the Quark Spin Contribution to the Proton Spin SLAC (E80 and E130) vs CERN (EMC) ∫g1(x)dx=∫A1(x)*F2(x)/[2x(1+R(x))]dx A1(x) 0.1<xSLAC<0.7 Ellis-Jaffe sum rule Proton spin crisis: x-Bjorken x-Bjorken Proton Spin = 1/2h = Quark Spin + Gluon Spin + Orbital Angular Momentum ≈0.1 EMC, Phys.Lett.B206:364,1988: 1200 citations! E130, Phys.Rev.Lett.51:1135,1983: 382 citations.