T. Kawamoto1 ATLAS muon small wheels for ATLAS phase-1 upgrade LHCC T. Kawamoto (New) small wheels ? Why new small wheels for high luminosity ? Detector technologies Schedule

T. Kawamoto2 The small wheels The innermost station of the muon endcap Located between endcap calo and toroid L1 trigger chambers EI station small wheel

T. Kawamoto3  = 1.3 – 2.0: MDT (precision R) + TGC (  coordinate)  = 2.0 – 2.7: CSC (precision R and  )

T. Kawamoto4 Motivation of upgrade – 1/2 Extrapolated cavern background in the small wheel MDT rate limit 1x10 34 is OK, but little margin for higher lumi Cavern background Hit rate 14 TeV Al beam pipe Measured cavern background in the small wheel 7 TeV

T. Kawamoto5 Motivation of upgrade – 1/2 CSC limit

T. Kawamoto6 Motivation of upgrade – 2/2 MU20 vs  2010/2011 data MU11 vs  25 ns test in 2011 ~ 6-7x higher L1 rate in Endcap than in the barrel Additional background (+40%) In  = 1.0 – ns interval L1 background

T. Kawamoto7 What is the origin of these fakes ? TOF measurement with MDT EM and EO Slow particles ! FLUGG MC protons and their birth position (  ) FLUGG MC Protons produced in/after the EC toroid – No hits in Small Wheels Motivation of upgrade – 2/2  timing EMEO

T. Kawamoto8 New small wheels Kill the fake trigger by requiring high quality (   ~ 1mrad) IP pointing segments In New small wheels (NSW) New precision tracker in NSW that works up to the ultimate luminosity, 5-7x10 34, with some safety margin Present L1 Upgrade L1 with NSW

T. Kawamoto9 Extrapolated L1 rate at 14 TeV, 25ns At L = 3x10 34 Single  L1 rate (kHz) Mu20Mu40 Without NSW6029 With NSW2210 NSW + phase NSW is vital for running at high luminosity. Allowing low p T thresholds Total L1 bandwidth is ~75 kHz, will be 100 kHz after phase-0

T. Kawamoto10 NSW detector technology The baseline technology, defined in May, is a combination of sTGC and MicroMegas Critical milestones  end 2012 sTGC  trigger, bunch id MM  precision tracking but each has both functions ~100  m precision Complementarity Redundancy Robust detector Important feature for a detector of limited access (space, ALARA) sTGC Micromegas sTGC MM

T. Kawamoto11 NSW detector technology 2M+ r/o channels New front-end ASIC, designed for both MM and sTGC MM resistive strip structure : spark protection sTGC with charge r/o from strips 1 st prototype, VMM1 successfully deployed in recent beam tests 128  m ~0.5 mm pitch

T. Kawamoto12 NSW detector technology 1x1m 2 MM in test beam Full size 1x2 m 2 MM will be built and tested this year. Large MicroMegas : built with PCB technology Industrialization is a next important step.

T. Kawamoto13 Full commissioning on surface The goal is establishing a firm base for achieving the timetable like this. Establish the procedure of prod & QA

Approval process Timeline for the Approval process: Initial design review: August Kick off Meeting: August 31 EB approval: September 14 CB approval: October 5 TDR & IMOU: 31. May T. Kawamoto

T. Kawamoto15 NSW will bring the muon spectrometer significant enhancements that cannot be achieved by simple modifications.

T. Kawamoto16 Back up

T. Kawamoto17 LHC and ATLAS upgrade ∫ L dt Year phase-0 phase-1 phase /142018~ TeV→14 TeV → 2x10 33 cm -2 s -1 → 1x10 34 cm -2 s -1 1x10 34 → ~2x10 34 cm -2 s -1 Now ~20 fb -1 ~50 fb -1 ~300 fb fb -1 → 5x10 34 cm -2 s -1 luminosity leveling Possible upgrade timeline new shielding winter elevator hole chambers trigger in barrel feet region New small wheel And more Integrating small wheel TGC in Endcap L1 : update SL programing LS2 LS1 LS3

T. Kawamoto18 New small wheels Trigger rate reduction ~ 1/6 ~ 1/6 in 1.3<  <2.4  dependence of rejection EI segment IP pointing Matched to BW No visible  dependence Expected L1 improvement Study using pp collision data. Emulation of NSW using MDT+CSC data

T. Kawamoto19 Phase-0 : integrating EI in L1 Require hits in EI associated to the BW TGC track. Coverage :  = 1.05 – 1.9 Reduction for “L1 MU11” 81.0% Eff. for offline Pt>MU % ~ 1/2 reduction in the region of coverage SL firmware update

T. Kawamoto20 Phase-1 NSW coverage Trigger and tracking improved by NSW Phase-0 coverage

T. Kawamoto21 NSW spec is designed for further upgrade NSW initial goal : to remove fakes. Designed also for improving p T of L1 size of luminous region 1-2 mrad multiple scattering in the calorimeter 2-3 mrad multiple scattering in the EC toroid 1 mrad angular resolution of BW 3 mrad measure and correct with NSW: need 1 mrad resolution upgrade of BW (phase-2) nominal threshold p T after fake removal with NSW

T. Kawamoto22 NSW critical milestones MM Validation of detector resolution for inclined tracks (  TPC mode) Realization of full size detector Investigation of possible damages by sparks (large ionization) sTGC Demonstrator of trigger Common items Geometrical accuracy and alignment Effect of magnetic field Reporting items MM industrialization MM trigger Combination of trigger information from sTGC and MM TGC production sites Alignment NSW layout Long term ageing tests Performance under radiation background To be achieved by the end of 2012  finalizing the technology Making good progress

T. Kawamoto23 Resistive MM PCB Mesh Resistivity values R G ≈ 55 MΩ R strip ≈ 35 MΩ/cm Resistive strips x strips y strips

T. Kawamoto24 Clean signals up to >1 MHz/cm 2, but some loss of gain Gain ≈ 5000 Max. NSW rates