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Linear Collider Detectors
Jim Brau Univ. of Oregon Fermilab April 5, 2002

· Many open issues for LC detectors · Physics goals involve low event rates with relatively low backgrounds
­ opportunity for novel approaches

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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The "next" Linear Collider
The "nex t" L inear C o lli de r proposa l s in c lude plans to de li ve r a few hundred fb -1 o f i n teg r a ted lu m . pe r y ea r

TESLA
(DESY-Germany)

JLC-C
(Japan)

NLC/JLC-X *
2.2 3.4 500 1000 70 11.4 1.4 190 4.6 8.8

(SLAC/KEK-Japan)

Ldesign
E
CM

(1034) (GeV) (GHz) (ns)

3.4 5.8 500 800 23.4 35 1.3 337 176 2820 4886 3.2 4.4

0.43 500 34 5.7 2.8 72

Eff. Gradient (MV/m) RF freq.

tbunch
#bunch/train

Beamstrahlung (%)

* US and Japanese X-band R&D cooperation, but machine parameters may differ
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Detector Requirements
There is perception that Linear Collider Detectors are trivial Not true! But requirements are orthogonal to hadron collider requirements Here are some comparisons
Tracker thickness: CMS ATLAS LC 0.30 X0 0.28 X0 0.05 X0

Vertex Detector layer thickness CMS 1.7 % X0 ATLAS 1.7 % X0 LC 0.06% X0
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Detector Requirements
Vertex Detector granularity CMS 39 Mpixels ATLAS 100 Mpixels LC (Telsa) 800 Mpixels ECAL granularity (detector elements) CMS 76 x 103 ATLAS 120 x 103 LC(Tesla) 32 x 106

Unburdened by high radiation and high event rate, the LC can use 6 times less material in tracker vxd 3-6 times closer to IP 35 times smaller pixels and 30 times thinner vxd layers > 200 times higher ECAL granularity (if it's affordable)
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues
Time structure

NLC (JLC)

Tesla

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues
Time structure NLC (JLC) 190 bunches/train 1.4 ns bunch spacing crossing angle (20 mrad) - (8 mrad for JLC) might want to time-stamp within train? Tesla 2820 bunches/train 950 µsec long no crossing angle, but could have one very much higher duty cycle (how to deal with?)

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues
Solenoid effects transverse component of solenoid must be compensated - straight forward NLC - L Detector IR Layout L* = 3.8 m Masks M1 - W/Si M2 - W Low-Z
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues
Small spot size issues nm vertical stability required
permanent magnets for QD0 and QF1

passive compliance + active suppression

15 ns response within bunch train (NLC)

Beam-beam interaction broadening of energy distribution (beamstrahlung) ~5% of power at 500 GeV backgrounds
e+e- pairs radiative Bhabhas low energ tail of disrupted beam neutron "back-shine" from dump hadrons from gamma-gamma

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues
3 Tesla
VXD limit

100,000

50,000

e+e- pairs

Hits/bunch train/mm2 in VXD, and photons/train in TPC
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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IR Issues

Synchrotron radiation photons from beam halo in the final doublet halo limited by collimation system
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Detector Requirements
Vertex Detector physics motivates excellent efficiency and purity large pair background from beamstrahlung large solenoidal field ( 3 Tesla) pixelated detector [(20 µm)2 2500 pixels/mm2] min. inner radius (< 1.5 cm), ~5 barrels, < 4 µm resol, thickness < 0.2 % X0 Calorimetry excellent jet reconstruction eg. W/Z separation use energy flow for best resolution (calorimetry and tracking work together) fine granularity and minimal Moliere radius charge/neutral separation large BR2
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Detector Requirements
Tracking robust in Linear Collider environment isolated particles (e charge, µ momentum) charged particle component of jets jet energy flow measurements assists vertex detector with heavy quark tagging forward tracking (susy and lum measurement) Muon system high efficiency with small backgrounds secondary role in calorimetry ("tail catcher") Particle ID dedicated system not needed for primary HE physics goals particle ID built into other subsystems (eg. dE/dx in TPC)

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Beamline requirements
Beam energy measurement Need 50-100 MeV (10-4) precision SLD WISRD technique is probably adequate (needs work) TESLA plans BPM measurement pre-IP (needs work) Luminosity spectrum acolinearity of Bhabhas question - can it be extracted from WISRD? What about effect of beam disruption Polarization measurement SLD achieved 0.5% - same technique at NLC should give 0.25% TESLA plans only before IP (is this okay? NLC bias says no) Positron polarization helps dramatically
LC Detectors, Jim Brau, Fermilab, April 5, 2002

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LC Detectors
Tesla TDR Detector American High Energy IR 1.) L conventional large detector based on the early American L (Sitges/Fermilab LCWS studies) 2.) SD (silicon detector) motivated by energy flow measurement JLC Detector 3 Tesla

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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LC Detectors
TESLA TDR · "pixel" vertex detector · silicon/W EM calorimeter (energy-flow) · 4 T coil

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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LC Detectors
· TESLA TDR

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book L Detector
5 barrel CCD vertex detector 3 Tesla Solenoid outside hadron calorimeter TPC Central Tracking (52 190 cm) Intermediate Si strips at R=48 cm Forward Si discs (5 each) Pb/scintillator EM and Had calorimeter EM 40 x 40 mrad2 Had 80 x 80 mrad2 Muon - 24 5 cm iron plates with gas chambers (RPC?)

Solenoid

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book L Detector

Solenoid

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book SD Detector
5 barrel CCD vertex detector 5 Tesla Solenoid outside hadron calorimeter Silicon strips or drift (20 125 cm) 5 layers Forward Si discs (5 each) W/silicon EM calorimeter 0.5 cm pads with 0.7 X0 sampling and Cu or Fe Had calorimeter (4 ) 80 x 80 mrad2 Muon - 24 5cm iron plates with gas chambers (RPC?)
Solenoid

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book SD Detector

Solenoid

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book HE Detector Comparison
L Solenoid R(solenoid) 3T 4.1 m SD 5T 2.8 m

BR2 (tracking) 12 m2T 8 m2T -------------------------------------------------------------------RM (EM cal) 2.1 cm 1.9 cm 3.8 0.26 trans.seg RM 0.6 (6th layer Si) -------------------------------------------------------------------Rmax(muons) 645 cm 604 cm

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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Resource Book P Detector
5 barrel CCD vertex detector 3 Tesla Solenoid inside hadron calorimeter TPC Central Tracking (25 150 cm) Pb/scintillator or Liq. Argon EM and Hadronic calorimeter EM 30 x 30 mrad2 Had 80 x 80 mrad2 Muon - 10 10cm iron plates w/ gas chambers (RPC?)

LC Detectors, Jim Brau, Fermilab, April 5, 2002

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