Muon Detection

1
Muon Detection Measurement _at_ SLHC

• Frank Taylor
• MIT
• Intnl Workshop on Future Hadron Colliders
• FNAL October 16-18, 2003

ATLAS
CMS
2
Critical Issues

• Rate demand on tracking trigger technologies
• Occupancy vs. pattern recognition
• Ghost tracks Track Matching between ID Muons
• Trigger PT resolution Rate
• Stability of chamber parameters under rate
• Space charge effects, R-T relation affected
• Spatial resolution vs. rate
• Beam crossing timing
• Longevity
• Chambers Electronics (Rad Hard SE Upsets)
• Shielding size activation
• Thick enough
• Personnel access

3
SLHC Environment
600 _at_ RHIC
4
CMS Muon System

• Three types of gaseous detectors
• Drift Tubes in Barrel (DTs)
• Cathode Strip Chambers in Endcaps (CSCs)
• Resistive Plate Chambers (RPCs) in both barrel
  and endcaps
• Coverage ? lt 2.4

5
ATLAS Muon System

• Muon Spectrometer
• Toroidal magnetic field ltBgt 0.4 T
• Air-core coils
• 3 detector stations
• - cylindrical in barrel
• - wheels for endcaps
• Coverage ? lt 2.7

• Technologies
• Fast trigger chambers TGC, RPC
• High resolution tracking detectors MDT, CSC

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CMS Barrel Drift Tube Chambers
Drift time 320 to 400 ns
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Monitored Drift Tube Chambers (MDT)
Barrel

• 6 / 8 drift tube layers, arranged in
• 2 multilayers glued to a spacer frame
• Length 1 6 m, width 1 2 m
• Gas ArCO2 (937) _at_ 3 bar
• Maximum drift time 600 ns

End Cap
8
CMS CSC Endcap

• 468 CSCs of 7 different types/sizes
• gt 2,000,000 wires (50 mm)
• 6,000 m2 sensitive area
• 1 kHz/cm2 rates
• 2 mm and 4 ns resolution/CSC (L1-trigger)
• 100 ?m resolution/CSC (offline)

Charge integration time 400 ns
9
Gas Detectors-Tracking Technologies

• CMS
• f precision coordinate
• Drift Tubes (DT) In barrel 0lthlt1
• 40 mm x 13 mm cell
• 2nd coordinate
• Beam crossing time
• t 400 ns
• Cathode Strip Chambers (CSC) in endcap 1lthlt2.4
• 2-D readout
• f strips 3 to 16 mm

• ATLAS
• q precision coordinate
• Monitored Drift Tubes (MDT) in Barrel Endcap
  0lthlt2.7 except 1st layer
• 30 mm dia. cell
• t 600 ns
• 2nd Coordinate RPC in barrel TGC in endcap
• CSC inner endcap layer 2.0lthlt2.7
• 2-D readout
• q strips 3 mm
• f strips 10 mm

10
ATLAS l vs. h
Design Criterion m-rate dominated by prompt
decays in inner tracker volume CMS 10 to 15 l in
front of M1 station
11
Neutron Flux ATLAS _at_ 1034 cm-2 s-1
2-10 mSv/h in access
4
20
100

• (MDT) 5x10-4 e (CSC) 2x10-4
• (RPC) 5x10-4 e (TGC) 10-3

N neutrons (kHz/cm2)
_at_ 300 keV but strongly energy dependent
12
Photon Flux ATLAS _at_ 1034 cm-2 s-1
2
4
20

• (MDT) 8x10-3 e (CSC) 5x10-3
• (RPC) 5x10-3 e (TGC) 5x10-3

N photons (kHz/cm2)
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Rate Cross section vs. PT - ATLAS
m
m
m
mb/GeV
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Muon Chamber Counting Rate ATLAS _at_ 1034
gs are dominate component
_at_ 1035 -gt max rate 10 kHz/cm2 MDT 0.5 C/cm-yr
Calorimeter Electronics Chimney TDR
now smaller
15
Muon Track in ATLAS 5 X Bkg. _at_ 1034
Occup. 10
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Precision Tracking Chamber Occupancy
L 5x1034 cm-2 s-1 MDT CSC
2X larger acceptable 10X larger very
uncomfortable and something has to done
Occupancy ()
17
MDT Performance under Rate
single tube resolution vs. drift radius
, ArCO2(937), 3 bar
Degradation due to space charge fluctuations
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Luminosity effects
H?ZZ ? ??ee event with MH 300 GeV for
different luminosities
1032 cm-2s-1
1033 cm-2s-1
Praha July 2003
1034 cm-2s-1
1035 cm-2s-1
SLHC prospects Albert De Roeck (CERN)
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Pattern Recognition to be Studied

• Track matching between ID Muon System
• Spatial matching
• 1/P matching
• Second Coordinate Ghost tracks
• Muon Track Isolation
• Decay ms from b, c, p, K
• Dominate Bkg from H -gt ZZ -gt mmmm is tt and Zbb
• Isolation cut DR (Dh2 Df2)1/2 lt Rmax

20
Trigger Issues

• Resolution
• Sharpness of Pt turn-on
• Rate
• Reals Accidentals
• Possible to raise threshold ?
• Resolution Accidentals permitting

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CMS
Trigger primitive developed from track curvature
in muon system of DT, CSC, RPC
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ATLAS Muon Trigger Primitives
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RPC used in both CMS ATLAS
3 mm gap

• Intrinsically fast response 3 ns
• RD effort to understand long term
  characteristics
• Rate handling depends on electrode resistivity
• r observed to increase by 2 orders of magnitude

24
Thin Gap Chambers (TGC) in ATLAS
Not to scale

• Small drift distance close wire spacing t 25
  ns
• 1.8 mm wire spacing, 1.4 mm anode - cathode
• Has to use a heavily quenched gas

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TGC Timing
TGC inefficient for 12.5 ns beam crossing interval
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Trigger PT Resolution
e _at_ turn-on important
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Trigger Resolution Rate
Accidentals X 10 Accidentals
6 GeV
_at_ 1035 (100 nb-1 s-1 ) Trig Rate 104 Hz
mostly real if accidental rate nominal higher
thresholds larger fraction of accidentals
20 GeV
20 GeV
6 GeV
28
Conclusions

• RD Program
• Experience with LHC running
• Calibration of shielding Backgrounds
• Identify the real problems
• Detector issues clear at this time (2003)
• Faster More Rad-Hard trigger technology needed
• RPCs (present design) will not survive _at_ 1035
• TGCs need to be faster perhaps possible
• Gaseous detectors only practical way to cover
  large area of muon system (DT, MDT CSC) Area
  104 m2
• Better test data needed on resoln vs. rate
• Bkg. g and neutron efficiencies
• Search for faster gas gt smaller drift time
• Drive technologies to 1035 conditions
• Technologies DT, MDT CSC not precluded