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

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

Motivation The origin of the proton spin u u d Spin ½ quarks Spin ½ q-bars Spin 1 gluons 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) February 13, 2008 RPC2007-Mumbai

Present Understanding (Ref.) M. Hirai, S. Kumano, N. Saito, Phys. Rev. D 74, 014015 (2006) Spin dependent quark distribution functions by the QCD analysis of DIS data Δq(x) : well known, Δq(x) : not well known x Spin dependent gluon distribution functions by the QCD analysis of DIS data ΔG = 0.47 ∓ 1.08 (largely unknown) February 13, 2008 RPC2007-Mumbai

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, AL, of W+ and W-. R L February 13, 2008 RPC2007-Mumbai

Analysis Method The quark and antiquark polarizations of the proton can be estimated through AL, at Q 2 = MW2, x1>>x2 x2>>x1 February 13, 2008 RPC2007-Mumbai

Experimental Requirement Design Luminosity of RHIC L = 2x1032/cm2/s for √s = 500 GeV σtot = 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, 2008 RPC2007-Mumbai

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

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, 2008 RPC2007-Mumbai

Specific Characteristics of Trigger RPC Characteristics of double gap RPC in avalanche mode as a muon trigger detector Time resolution 1 ~ 2 ns for M.I.P. Efficiency > 95 % for M.I.P. Rate capability 1 ~ 2 kHz/cm2 Noise rate for plain RPCs 10 ~ 50 Hz/cm2 for ~ 1010Ohm∙cm Noise rate for oiled RPCs 0.5 ~ 5 Hz/cm2 for ~ 1010Ohm∙cm Resistivity of resistive plates 1010 ~ 1011 Ohm∙cm Typical strip multiplicity 1.5 ~ 3.0 February 13, 2008 RPC2007-Mumbai

Efficiency Typical shape of the efficiency Efficiencies for 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, 2008 RPC2007-Mumbai

Time Resolution Time spectrum at 9.0 kV with Th = 270 fC Time resolutions as a function of HV FWHM ~ 3 ns No SF6 No SF6 February 13, 2008 RPC2007-Mumbai

Charge Our definition of the avalanche charge <q> < 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 SF6 February 13, 2008 RPC2007-Mumbai

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

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 1997. 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, 2008 RPC2007-Mumbai

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

February 13, 2008 RPC2007-Mumbai

Flow of RPC Gaps and Parts for PHENIX bakelite route gas cell route frames and parts Korea BNL China Italy ►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. February 13, 2008 RPC2007-Mumbai

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/m2/gap at working HV (9.4 kV at 1013 hPa) Assignment of the bar code only for the qualified gas gaps February 13, 2008 RPC2007-Mumbai

Current Limits for PHENIX PHENIX Region Current limit for each gap at 8.5 kV (μA) at 9.4 kV (μA) Current limit for RPC RE3 Ring 1-2 (N+S) 1 2 10 RE3 Ring 3-4 (N+S) 4 15 RE3 Ring 5-6 (N+S) 3 5 RE2 Ring 1-2 (N+S) RE2 Ring 3-4 (N+S) RE2 Ring 5-6 (N+S) RE2 Ring 7-8 (N+S) February 13, 2008 RPC2007-Mumbai

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

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 λI) thick Cu in one arm ~June Start the mass production of RPC gaps for PHENIX RPC 3A RPC 3B RPC 3C February 13, 2008 RPC2007-Mumbai

PHENIX Schedule II 2009 2010 2011 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, 2008 RPC2007-Mumbai

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) RPC2 (South) Finish by the end of 2009 RPC1a (both arms) 16(48) ~1 RPC1b (both arms) 16(64) Finish by the end of 2010 Sum 256 (560) ~13 February 13, 2008 RPC2007-Mumbai

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 2011. 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, 2008 RPC2007-Mumbai

Back-up Slides February 13, 2008 RPC2007-Mumbai

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. February 13, 2008 RPC2007-Mumbai