25.09.2012 T. Kawamoto 1

ATLAS muon small wheelsfor ATLAS phase-1 upgrade

LHCC

25.09.2012

T. Kawamoto

• (New) small wheels ?• Why new small wheels for high luminosity ?• Detector technologies• Schedule

25.09.2012 T. Kawamoto 2

The small wheels

The innermost station of the muon endcap

Located between endcap calo and toroid

L1 triggerchambersEI station

small wheel

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= 1.3 – 2.0 : MDT (precision R) + TGC ( coordinate)

= 2.0 – 2.7 : CSC (precision R and )

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Motivation of upgrade – 1/2

Extrapolatedcavern backgroundin the small wheel

MDT rate limit

1x1034 is OK, but little marginfor higher lumi

Cavern background

Hit rate14 TeVAl beam pipe

Measured cavern backgroundin the small wheel

7 TeV

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Motivation of upgrade – 1/2

CSC limit

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Motivation of upgrade – 2/2

MU20 vs 2010/2011 data

MU11 vs 25 ns test in 2011

~ 6-7x higher L1 rate in Endcapthan in the barrel

Additional background (+40%) In = 1.0 – 1.5

50 ns interval

L1 background

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What is the origin of these fakes ?

TOF measurementwith 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

EM EO

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New small wheels

• Kill the fake trigger by requiring high quality (~ 1mrad)IP pointing segments In New small wheels (NSW)

• New precision tracker in NSWthat works up to the ultimate luminosity,5-7x1034 , with somesafety margin

Present L1

Upgrade L1 with NSW

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Extrapolated L1 rate at 14 TeV, 25ns

At L = 3x1034

Single L1 rate (kHz)

Mu20 Mu40

Without NSW 60 29

With NSW 22 10

NSW + phase-0

17 8

NSW is vital for running at high luminosity.

Allowing low pT thresholdsTotal L1 bandwidth is ~75 kHz,will be 100 kHz after phase-0

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NSW detector technology

The baseline technology, defined in May, is a combination of sTGC and MicroMegas

Critical milestones end 2012

sTGC trigger, bunch idMM precision tracking

but each has both functions ~100 m precision

• Complementarity• Redundancy• Robust detector

Important feature for a detectorof limited access (space, ALARA)

sTGC

Micromegas

sTGC

sTGC

MM

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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

1st prototype, VMM1successfully deployed in recent beam tests

128 m

~0.5 mm pitch

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NSW detector technology

1x1m2 MM in test beam

Full size 1x2 m2 MM will be built and tested this year.

Large MicroMegas : built with PCB technology

Industrialization is a next important step.

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Full commissioningon 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 29-30

•Kick off Meeting: August 31

•EB approval: September 14

•CB approval: October 5

•TDR & IMOU: 31. May 2013

1425.09.2012 T. Kawamoto

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NSW will bring the muon spectrometer significant enhancements

that cannot be achieved by simple modifications.

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Back up

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LHC and ATLAS upgrade∫ L

dt

Year

phase-0

phase-1

phase-2

2013/14 2018 ~2022

7 TeV →14 TeV

1027 →2x1033cm-2s-1

→ 1x1034cm-2s-1

1x1034 →~2x1034cm-2s-1

Now

~20 fb-1

~50 fb-1

~300 fb-1

3000 fb-1

→ 5x1034cm-2s-1

luminosity leveling

Possible upgrade timeline

• new shielding winter 2011-12

• 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

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New small wheels

Trigger rate reduction ~ 1/6

~ 1/6in 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

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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>MU10 98.6%

~ 1/2 reduction in theregion of coverage

SL firmware update

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Phase-1 NSW coverage

Trigger and tracking improved byNSW

Phase-0 coverage

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NSW spec is designed for further upgrade

NSW initial goal : to remove fakes.

Designed also for improving pT 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 correctwith NSW: need 1 mrad resolution

upgrade of BW (phase-2)

nominal threshold

pT after fake removal with NSW

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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 triggerCommon 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

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Resistive MM

PCBPCB

Mesh

Resistivity valuesRG ≈ 55 MΩRstrip ≈ 35 MΩ/cm

Resistive stripsResistive strips

x stripsx strips

y stripsy strips

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Clean signals up to >1 MHz/cm2,but some loss of gain

Gain ≈ 5000

Max

. N

SW

rat

es