February 13, 2008RPC2007-Mumbai1 RPC Production for Fast Muon Trigger System for Byungsik Hong Korea University for the PHENIX Collaboration

February 13, 2008RPC2007-Mumbai2 Contents  Motivation  Characteristics for PHENIX RPCs  Quality assurance plan  Schedule Gap production and installation  Summary

February 13, 2008RPC2007-Mumbai3 Motivation  The origin of the proton spin u u d Quark Spin ΔΣ = 0.25 ∓ 0.10 → known as Spin Crisis Ref.) EMC, Phys.Lett.B206, 364 (1988); Nucl.Phys.B328, 1 (1989) Spin ½ quarks Spin ½ q-bars Spin 1 gluons

February 13, 2008RPC2007-Mumbai4 Present Understanding x  Spin dependent gluon distribution functions by the QCD analysis of DIS data ΔG = 0.47 ∓ 1.08 (largely unknown) (Ref.) M. Hirai, S. Kumano, N. Saito, Phys. Rev. D 74, (2006)  Spin dependent quark distribution functions by the QCD analysis of DIS data Δq(x) : well known, Δq(x) : not well known

February 13, 2008RPC2007-Mumbai5 Detailed Quark and Antiquark Spins  Main motivation of the PHENIX RPC upgrade  W-boson production The sea quark polarizations of the proton can be probed by The single spin asymmetry, A L, of W + and W -. R L

February 13, 2008RPC2007-Mumbai6 Analysis Method  The quark and antiquark polarizations of the proton can be estimated through A L, at Q 2 = M W 2, x 2 >> x 1 x 1 >> x 2

February 13, 2008RPC2007-Mumbai7 Experimental Requirement Design Luminosity of RHIC L = 2x10 32 /cm 2 /s for √s = 500 GeV σ tot = 60 mb Raw rate at PHENIX = 12 MHz PHENIX DAQ limit ≈ 2 kHz for muon arms Required RF ~ 6,000 Cf.) Current RF by MuID trigger ~ 500 We need to introduce the muon trigger, based on the momentum measurement. → RPC based muon trigger upgrade

February 13, 2008RPC2007-Mumbai8 PHENIX RPC Locations RPC1(a,b)RPC2 RPC3 We need total 256 RPC modules. (For the detailed plan, see Rusty Towell’s talk in PL-8 on Friday.)

February 13, 2008RPC2007-Mumbai9 Why do we employ RPC?  General characteristics of RPC Fast response - Suitable for the trigger device Good timing resolution: 1~2 ns Good spatial resolution - Typically a few cm - Determined by the strip width and the cluster size Low production cost High-rate capability in avalanche mode

February 13, 2008RPC2007-Mumbai10 Specific Characteristics of Trigger RPC Characteristics of double gap RPC in avalanche mode as a muon trigger detector Time resolution1 ~ 2 ns for M.I.P. Efficiency> 95 % for M.I.P. Rate capability1 ~ 2 kHz/cm 2 Noise rate for plain RPCs10 ~ 50 Hz/cm 2 for ~ Ohm∙cm Noise rate for oiled RPCs0.5 ~ 5 Hz/cm 2 for ~ Ohm∙cm Resistivity of resistive plates10 10 ~ Ohm∙cm Typical strip multiplicity1.5 ~ 3.0

February 13, 2008RPC2007-Mumbai11 Efficiency Typical shape of the efficiency curve for various thresholds Efficiencies for double- and single gap (Ref.) S. H. Ahn et al., Nucl. Instrum. Methods A 508, 147 (2003)

February 13, 2008RPC2007-Mumbai12 Time Resolution FWHM ~ 3 ns No SF 6 Time spectrum at 9.0 kV with Th = 270 fC Time resolutions as a function of HV No SF 6

February 13, 2008RPC2007-Mumbai13 Charge  Our definition of the avalanche charge < 10 pC  Definition of the avalanche mode operation P(streamers) < 10%  Large pulse Large number of strips Cause difficulty for the reconstruction of high momentum muons No SF 6

February 13, 2008RPC2007-Mumbai14 For the specific R&D effort for the PHENIX RPC, see Beau Meredith’s talk in PL-11 on Sat. ~10 pC for the limit of avalanche ~2.7 pC at ε~95%

February 13, 2008RPC2007-Mumbai15 Korea Univ. & CMS The Korea Detector Laboratory (KODEL) of Korea University has been an active member of the CMS (Compact Muon Solenoid)/LHC at CERN since For more details, see the following two talks:  Sung Keun Park in PL-3 on Thursday  Kyong Sei Lee in PL-7 on Friday

February 13, 2008RPC2007-Mumbai16 Endcap Region of CMS Phase I Phase II Gap Production for CMS Endcap RPCs

February 13, 2008RPC2007-Mumbai17

February 13, 2008RPC2007-Mumbai18 ► Bakelites are produced and cut in Italy ► Gas gaps are produced at Korea University ► RPC frame & parts are procured in China (CIAE) ► Final assembly is done at BNL. Flow of RPC Gaps and Parts for PHENIX bakelite route gas cell route frames and parts Korea BNL China Italy

February 13, 2008RPC2007-Mumbai19 Quality Control of Gaps  Inspection of raw bakelite for the surface quality  Checking the graphite surface and the condition for PET coating  Test for gas leak and spacer bonding Add 20 hPa to each gap (1 hPa =1 mbar ) No detached spacers Pressure loss : < 0.2 hPa for 15 minutes  Test for high-voltage holding and current 1.5 days for flushing + 5 days for HV test Current limit for each gas gap right after the production: < 3 μA/m 2 /gap at working HV (9.4 kV at 1013 hPa )  Assignment of the bar code only for the qualified gas gaps

February 13, 2008RPC2007-Mumbai20 Current Limits for PHENIX PHENIX Region Current limit for each gap at 8.5 kV ( μ A) Current limit for each gap at 9.4 kV ( μ A) Current limit for RPC at 9.4 kV ( μ A) RE3 Ring 1-2 (N+S)1210 RE3 Ring 3-4 (N+S)2415 RE3 Ring 5-6 (N+S)3515 RE2 Ring 1-2 (N+S)1210 RE2 Ring 3-4 (N+S)2415 RE2 Ring 5-6 (N+S)2515 RE2 Ring 7-8 (N+S)3515

February 13, 2008RPC2007-Mumbai21 Examples of CMS Endcap RPCs 9.4 kV (72 h) 8.5 kV (12 h) Current ( μ A) Individual Gap ID Rejected Gaps Blue: begin Pink: end

February 13, 2008RPC2007-Mumbai22 PHENIX Schedule I  2008 January Send 6 sets of prototype C (RPC3A) gaps to BNL March Send prototype D gaps to BNL Complete RPC3 ‘half octant’ Install two ‘half octant’s in one arm One in the RPC2 and another one in the RPC3 positions Install one octant absorber made of ~30 cm (or 2 λ I ) thick Cu in one arm ~June Start the mass production of RPC gaps for PHENIX RPC 3A RPC 3B RPC 3C

February 13, 2008RPC2007-Mumbai23 PHENIX Schedule II  2009 Install absorber in the North arm Install RPC2 and RPC3 in the North arm  2010 Install absorber in the South arm Install RPC2 and RPC3 in the South arm  2011 Take out one nuclear interaction length absorber Install RPC1 in both arms Start to take the high statistics polarized p+p data

February 13, 2008RPC2007-Mumbai24 Current Production Plan PHENIX Region Number of RPC Modules (Gaps) Estimated months for production Tentative Schedule RPC3 (North)48(96)~ 2.5 Start ~June 2008 RPC2 (North)64(128)~ 3.0 Finish by the end of 2008 RPC3 (South)48(96)~ 2.5 RPC2 (South)64(128)~ 3.0 Finish by the end of 2009 RPC1a (both arms)16(48)~1 RPC1b (both arms)16(64)~1 Finish by the end of 2010 Sum256 (560)~13

February 13, 2008RPC2007-Mumbai25 Summary  The origin of the proton spin is the fundamental question of nuclear physics.  The PHENIX is upgrading the muon trigger system by using the RPCs in order to filter out the small cross-section W- candidate events. The flavor dependent quark and anti-quark spin distribution functions can be measured.  Korea University will produce all PHENIX RPC gas gaps. The mass production and installation will be completed by  Additional potential application of the L1 muon trigger for heavy-ion collisions still need to be explored, for example, Heavy-flavor trigger in combination with the forward vertex upgrade Dimuon trigger for the vector mesons for RHIC II

February 13, 2008RPC2007-Mumbai26 Back-up Slides

February 13, 2008RPC2007-Mumbai27 CMS Endcap RPC 1. Function : L1 muon triggers 2 wings (RE+, RE-) 4 stations (RE1, RE2, RE3, RE4) Pseudo rapidity coverage : 0.9 < η < 2.1 (1.6) η segmentations : 10 (6) 2. Total # of RPCs : 756 (432) Total # of FEBs : 2,268 (1,296) Total # of channels : 85,248 (41,472) 3. By March 2007, the gap production for phase I (0.9 < η < 1.6) was completed for the first operation of CMS in 2008.