Muon Detection & Measurement @ SLHC

Muon Detection & Measurement @ SLHC

Frank TaylorMIT

Int’nl Workshop on Future Hadron CollidersFNAL October 16-18, 2003

ATLASCMS

FNAL October 16-18, 2003 F.E. Taylor2

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


SLHC Environment

PARAMETER LHC SLHC

s (14 TeV)2 (14 TeV)2

L 1034/(cm2s) 1035/(cm2s)

Bunch Spacing 25 ns 12.5 ns

Interactions/Crossing ~ 12 ~ 62

dN/d - Crossing 75 375

Particle Flux 1st Muon Layer ~ 2.4

~ 1 kHz /cm2 ~ 10 kHz /cm2

Particle Flux 1st Muon Layer ~ 1

~ 20 Hz/cm2 ~ 200 Hz/cm2

~ 600 @ RHIC


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: || < 2.4


ATLAS Muon System

Muon Spectrometer:

• Toroidal magnetic field: <B> = 0.4 T

• Air-core coils

• 3 detector stations- cylindrical in barrel- wheels for endcaps

• Coverage: || < 2.7

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


CMS Barrel Drift Tube Chambers

Drift time ~ 320 to 400 ns


Monitored Drift Tube Chambers (MDT)

End Cap

Barrel

• 6 / 8 drift tube layers, arranged in 2 multilayers glued to a spacer frame• Length: 1 – 6 m, width: 1 – 2 m

• Gas: Ar:CO2 (93:7) @ 3 bar• Maximum drift time ~ 600 ns


CMS CSC EndcapCMS CSC Endcap

• 468 CSCs of 7 different types/sizes• > 2,000,000 wires (50 m)• 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


Gas Detectors-Tracking Technologies

• CMSprecision coordinate – Drift Tubes (DT) In barrel

0<||<1• 40 mm x 13 mm cell

• 2nd coordinate

• Beam crossing time

~ 400 ns

– Cathode Strip Chambers (CSC) in endcap 1<||<2.4

• 2-D readout

strips 3 to 16 mm

• ATLAS precision coordinate – Monitored Drift Tubes

(MDT) in Barrel & Endcap 0<||<2.7 except 1st layer

• 30 mm dia. cell ~ 600 ns

– 2nd Coordinate RPC in barrel & TGC in endcap

– CSC inner endcap layer 2.0<||<2.7

• 2-D readout strips 3 mmstrips ~ 10 mm


ATLAS vs. Design

Criterion

-rate dominated

by prompt & decays in

inner tracker volume

CMS10 to 15 in front of M1

station


Neutron Flux – ATLAS @ 1034 cm-2 s-1

100

(MDT) ~ 5x10-4 (CSC) ~ 2x10-4

(RPC) ~ 5x10-4 (TGC) ~ 10-3

204

N neutrons (kHz/cm2)

@ 300 keV but strongly energy dependent

2-10 mSv/h in access


Photon Flux – ATLAS @ 1034 cm-2 s-1

(MDT) ~ 8x10-3 (CSC) ~ 5x10-3

(RPC) ~ 5x10-3 (TGC) ~ 5x10-3

20

4

2

N photons (kHz/cm2)


Rate ‘Cross section’ vs. PT - ATLASb

/GeV

ddPtd ~ 4.4 x 103

Pt4.7

b/GeV


Muon Chamber Counting Rate – ATLAS @ 1034

Calorimeter Electronics “Chimney”

TDR now smaller

@ 1035 -> max rate ~ 10 kHz/cm2 MDT ~ 0.5 C/cm-yr

s are dominate component


Muon Track in ATLAS 5 X Bkg. @ 1034

Occup. ~ 10 %


Precision Tracking Chamber Occupancy

L ~ 5x1034 cm-2 s-1 MDT & CSC

Occupancy (%)

2X larger ~ acceptable

10X larger very uncomfortable and something

has to done


MDT Performance under Rate

Degradation due tospace charge fluctuations

single tube resolution vs. drift radius

, Ar:CO2(93:7), 3 bar


Luminosity effects

HZZ ee event with MH= 300 GeV for different luminosities

1032 cm-2s-

1

1033 cm-2s-

1

1034 cm-2s-

1

1035 cm-2s-

1

SLHC prospects Albert De Roeck (CERN)

Pra

ha Ju

ly 2

003


• Track matching between ID & Muon System– Spatial matching– 1/P matching

• Second Coordinate & Ghost tracks• Muon Track Isolation

– Decay s from b, c, , K • Dominate Bkg from H -> ZZ* -> is tt and Zbb

• Isolation cut R = (2 + 2)1/2 < Rmax

Pattern Recognition to be Studied


Trigger Issues

• Resolution– Sharpness of Pt turn-on

• Rate– Reals & Accidentals

• Possible to raise threshold ? – Resolution & Accidentals permitting


CMS

Trigger primitive developed from track curvature in muon

system of DT, CSC, RPC


ATLAS Muon Trigger Primitives


RPC – used in both CMS & ATLAS

• Intrinsically fast response ~ 3 ns

• R&D effort to understand long term characteristics• Rate handling depends on electrode resistivity

• observed to increase by 2 orders of magnitude

3 mm gap


Thin Gap Chambers (TGC) in ATLAS

• 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

Not to scale


TGC Timing

TGC inefficient for 12.5 ns beam

crossing interval


Trigger PT Resolution

@ turn-on important

(d2dPt

2 / d

dPt) ~ - 4.7/Pt


Trigger Resolution & Rate

20 GeV

6 GeV

20 GeV

6 GeV

Accidentals X 10

Accidentals

@ 1

035 (

100

nb-1 s

-1 )

Trig

Rat

e ~

10

4 H

z &

mos

tly ‘r

eal’

if ac

cide

ntal

ra

te n

omin

al –

hig

her

thre

shol

ds ~

la

rger

fra

ctio

n of

acc

iden

tals


Conclusions

• R&D 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 @ 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 resol’n vs. rate

– Bkg. and neutron efficiencies

– Search for faster gas => smaller drift time – Drive technologies to 1035 conditions

– Technologies DT, MDT & CSC not precluded

Muon Detection & Measurement @ SLHC

Documents

Transcript of Muon Detection & Measurement @ SLHC