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6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 1
Overview of LC DetectorsMark Oreglia, University of Chicago
Outline:• Physics drivers
• The TESLA-NAlarge design
• The Silicon Detector concept• The Global Large Detector•Thanks to: Bambade, Barklow, Behnke, Brau, Breidenbach, Damerell, Miller, Ronan, Schumacher, Sugimoto, Torrence, Woods, …
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 2
3 Archetype Physics Topics
• Light Higgs -- tracker– Best recoil mass resolution in Z-> dileptons
• Strong EWSB -- calorimeter– Important to look at WW scattering– W/Z jet separation crucial
• Some SUSY scenarios -- hermeticity– Cosmology “benchmarks” summarized: – “bulk” -> annihilation -> smuon/selectron– “coannihilation” -> sau annihil. -> staus– Low angle backgrounds
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 3
Momentum Resolution
• e+e-ZHllX• Golden physics
channel!
• (1/p) = 7 x 10-5/GeV
• 1/10 LEP !!!
• goal: M<0.1x • dominated by
beamstrahlung
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 4
Impact Parameter• d= 5 m 10/p(GeV) m • 1/3 SLD !!! • excellent flavor tagging capabilities for charm and
bottom quarks– Need exceptional tagging for reducing combinatorial
background in multi-jets ... – Charge assignment– Asymmetry measurements– (measurement of Higgs BRs not so sensitive!)
• The big question: inner VTX radius– No simple answer – physics reach gains with lever arm and
background suppresion, esp low momentum particles– … thus, low MS, small radius is essential– Needs more validation, but we are talking 1.5 cm radius!– Instrument lifetime issue
• Here we need you to tell us what is possible
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 5
(Jet) Energy Resolution
• E/E = 0.3/E(GeV)
• <1/2 LEP !!!
• MDijet ~ Z/W
• separation between e+e-WWqqqq and e+e-
ZZqqqq
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 6
Particle Flow
• reconstruction of multijet final states
• e+e- H+H- tbtb bqqb bqqb
• Emphasis on combined systems now
• System compataibility means fine granularity in calorimeters (1 cm2 !!!)
• Digital mode possible, if backgrounds controllable
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 7
Hermeticity
• hermetic down to = 5 mrad
• Important physics with missing energy topologies (SUSY , extra-dim, Higgs, ...)
• Background issues– Ability to veto low-pT particles
– Crossing angle optimization
• Excellent physics motivation: SUSY-stau– DeRoeck’s talk here– Bambade & Lohman in Forward Region session
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 8
IR-Related Issues
• Good measurements in the low-angle region– Need to make pT cuts for physics analyses– Need to mask and reduce occupancies in low angle region– Need convincing? See Bambade’s summary of X-angle mtg
• Beam-beam interaction• broadening of energy distribution
(beamstrahlung)• ~5% of power at 500 GeV• backgrounds• e+e- pairs• radiative Bhabhas• low energy tail of disrupted beam• neutron “back-shine” from dump• hadrons from gamma-gamma
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 9
Time Structure:
Event rates: Luminosity: 3.4x1034 cm-2 s-1 (6000xLEP)e+e-qq,WW,tt,HX 0.1 / train e+e-X:~200 /Train
Background from Beamstrahlung: 6x1010/BX 140000 e+e-/BX + secondary particles (n,)
950 µs 199 ms 950 µs
2820 bunches
5 Bunch Trains/s tbunch=337ns
But still: 600 hits/BX in Vtx detector 6 tracks/BX in TPC
E=12GeV/BX in calorimeters E 20TeV/BX in forward cals.
Large B field and shielding
High granularity of detectors and fast readout for stable pattern recognition and event reconstruction
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 10
IR Issues
Hits/bunch train/mm2 in VXD,and photons/train in TPC
pairs
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 11
Beam Energy
• need to know <E>lumi-weighted
• Some analyses require better than 0.1%Some analyses require better than 0.1%• techniques for determining the lumi-weighted
<ECM>:energy spectrometers Bhabha acolinearity
• Other possibilities :Z, ZZ and WW events; use existing Z and W
massutilize Bhabha energies in addition to Bhabha
acol-pair events; use measured muon momentum
• 200 ppm feasible; 50 ppm a difficult 200 ppm feasible; 50 ppm a difficult challengechallenge
Top-mass: need knowledge of E-spread FWHM to level of ~0.1%
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 12
Crossing Angle
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 13
Summary of MDI Issues
• Detector designers need input from MDI experts:– Minimum VTX radius (smaller than you’d like!)– Masking optimization and best model (MC tool) for backgrounds– Feasibility of crossing angle options
• Detector designers need MDI experts to appreciate:– Need for small on systematic <E>lumi
– Need for reduction in low-angle background– Need for diagnostic instrumentation
• This talk continues with a description of current designs– New tools are causing all to be rethought– I’ve completely neglected the special requirements of a
detector optimized for or e- collisions• Even worse low-angle background problems
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 14
There are currently 3 Detector Concepts
• The WorldWide Study is working on a plan:– organization of effort– benchmarking performance– cdr/tdr’s– selection
• 3 concepts are materializing:– The TESLA concept: TPC-tracker – Silicon tracker + calorimetry (SiD)– new large magnetic volume concept (Global
Large Detector, GLD)
• Rethinking as new information available
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 15
Comparison of 3 Concepts(thanks to Y. Sugimoto)
•Very large R•Jet chamber or TPC•Scintilator/W-Pb-Fe
•Moderate R•TPC tracker•SiW ECAL
•Si tracking and ECAL•Small R•Smallest granularity
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 16
TESLA (and NA Large Det)(Thanks to Ties Behnke, Mike Ronan, Markus Schumacher)
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 17
Basic TESLA Detector Concept
No hardware trigger, dead time free continous readout for complete bunch train (1ms)
Zero suppression, hit recognition and digitisation in FE electronics
Large gaseous central tracking device (TPC)
High granularity calorimeters
High precision microvertex detector
All inside magnetic field of 4 Tesla
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 18
Overview of tracking system
Central region:Pixel vertex detector (VTX)Silicon strip detector (SIT)Time projection chamber (TPC)
Forward region: Silicon disks (FTD) Forward tracking chambers (FCH)(e.g. straw tubes, silicon strips)
• B=4T, RTPC=1.7m: momentum resolution (1/p) < 7 x 10-5 /GeV
• American version has larger TPC outer radius (2m), lower B (3T)
• looking at various TPC pad designs and readout
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 19
Vertex Detector: Conceptual Design
5 Layer Silicon pixel detector
•Small R1: 15 mm (1/2 SLD)
•Pixel Size:20x20m2 Point =3 m
•Layer Thickness: <0.1%X0 suppression of conversions – ID of decay electrons minimize multiple scattering
800 million readout cells
Hit density: 0.03 /mm2 /BX at R=15mm pixel sensors
Read out at both ladder ends in layer 1: frequency 50 MHz, 2500 pixel rows complete readout in: 50s ~ 150BX
<1% occupancy no problem for track reconstruction expected
Impact parameterd ~R1 point
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 20
Flavour Tagging
•LEP-c
Powerful flavour tagging techniques (from SLD and LEP)
M
e.g. vertex mass
charm-ID: improvement by factor 3 w.r.t SLD
Expected resolution in r,and r,z
~ 4.2 4.0/pT(GeV) m
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 21
Gaseous or Silicon Central Tracking?gaseous silicone e H0A 0 b b b b
advantages of gaseous tracking: many pointssimple pattern recognitionredundancy
“but be careful with these comparisons!”This is something of an aesthetic argument
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 22
Forward Tracking
FTD: 7 Disks 3 layers of Si-pixels 50x300m2
4 layers of Si-strips r= 90m
FCH: 4 LayersStrawtubes or Silicon strips (double sided)
250 GeV
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 23
Particle / Energy Flow60 % charged particles:30 % :10 %KL,nThe energy in a jet is:
Reconstruct 4-vectors of individual particles avoiding double counting
Charged particles in tracking chambersPhotons in the ECALNeutral hadrons in the HCAL (and possibly ECAL)
need to separate energy deposits from different particles
• small X0 and RMoliere : compact showers
• high lateral granularity D ~ O(RMoliere)
• large inner radius L and strong magnetic field
granularity more important than energy resolution
KL,n
e Discrimination between EM and hadronic showers
• small X0/had • longitudinal segmentation
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 24
Calorimeter Conceptual Design
ECAL and HCAL inside coil
large inner radius L= 170 cm good effective granularity
x~BL2/(RM D) 1/p
x distance between charged and neutral particle at ECAL entrance
•ECAL: SiW, •40 layers/24Xo/0.9lhad, 1cm2 lateral segmetation • E/E = 0.11/E(GeV) 0.01
•HCAL: many options• scintilator tiles, analog or digital• steel-scintillator sandwich
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 25
Forward Calorimeters
LCAL: Beam diagnostics and fast luminosity (28 to 5 mrad) ~104 e+e— pairs/BX 20 TeV/BX 2MGy/yr Need radiation hard technology: SiW, Diamond/W Calorimeter or Scintillator Crystals
LAT: Luminosity measurement from Bhabhas (83 to 27 mrad) SiW Sampling Calorimeter
aim for L/L ~ 10-4 require = 1.4 rad
TDR version of mask L* = 3 m
Tasks:
Shielding against background
Hermeticity / veto
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 26
SiD Design Starting Point(Thanks to Marty Breidenbach, John Jaros)
B = 5T Recal = 1.25m Zecal = 1.74m
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 27
The SiD Rationale
Premises:particle flow calorimetry will deliver the best possible performance
Si/W is the right technology for the ECAL
Excellent physics performance, constrained costs
Si/W calorimetry for excellent jet resolution
therefore…
• Limit Si/W calorimeter radius and length, to constrain cost
• Boost the B field to recover BR2 for particle flow, improve momentum resolution for tracker, reduce backgrounds for VXD
• Use Si microstrips for precise tracking
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 28
Cost (and physics) balance R and BHigh Field Solenoid and Si/W Ecal are major cost drivers.
Magnet Costs Stored Energy (SiD ~1.1GJ 80-100 M$) Cost [M$]
Fix BR2=7.8, tradeoff B and R
Stored Energy [GJ]
Delta M$ vs B, BR2=7.8 [Tm2]
Cost Partial, Fixed BR^2
0
10
20
30
40
50
60
70
0 1 2 3 4 5 6
B
Del
ta M
$
1.25
1.35
1.45
1.55
1.65
1.75
1.85
Linear
Power
Radius
0.00
50.00
100.00
150.00
200.00
250.00
0 0.5 1 1.5 2 2.5 3 3.5 4
Linear
Power
Exp Data
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 29
ECAL
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 30
Si Detector/ Readout Chip
Readout ~1k pixels/detectorwith bump-bonded ASIC
Power cycling – only passive cooling required
Dynamic range OK(0.1 - 2500 mip)
Pulse Height and Bunch Label buffered 4 deep to accommodate pulse train
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 31
HCAL
• Inside the coil• Rin= 1.42m; Rout= 2.44m• 4 Fe (or W, more compact)
2cm Fe, 1cm gap• Highly segmented
1x1 cm2 – 3x3 cm2 ~ 40 samples in depth
• Technology?RPCScint TileGEM
S. Magill (ANL)…many critical questions for the SiD Design Study: thickness? Segmentation? Material? Technology?
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 32
Silicon TrackingWhy silicon microstrips? SiD starting point
Robust against beam halo
Thin, even for forward tracks. Won’t degrade ECAL
Stable alignment and calibration. Excellent momentum resolution
p/p2~2 x 10-5
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 33
VXD Tesla SiD
Shorten barrel, add endcaps. Shorten Barrel CCDs to 12.5 cm (vs. 25.0cm)
add 300 m Si self-supporting disk endcapssupporting disk endcaps (multiple CCDs per disk) (multiple CCDs per disk)
This extends 5 layer tracking over max , improves forward pattern recognition.improve Coverage, improve impact param
5 CCD layers .97 (vs. .90 TDR VXD) 4 CCD layers .98 (vs. .93 TDR VXD)Readout speed and EMI are big questions.
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 34
SiD SubsystemsSo far, we’ve concentrated on calorimetry, tracking, and
magnet, since they define SiD architecture.Other subsystems need development & integration.• Flux Return/Muons/Had Tail Catcher
B field homogeneity for forward ecal?Longitudinal segmentation?Technology?
• Very Forward TrackingPixels or strips?
• Very Forward Cal (huge and active area!)Active masks and vetoesLumcalBeamcal (pair monitor)
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 35
Global Large Detector(Thanks to Y. Sugimoto)
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 36
Basic design concept
Detector optimized for Particle Flow Algorithm (PFA)
• Large/Huge detector concept
– GLC detector as a starting point– Move inner surface of ECAL outwards to optimize for PFA
– Larger tracker to improve pt/pt2
– Re-consider the optimum sub-detector technologies based on the recent progresses
• Different approaches
– B Rin2 : SiD
– B Rin2 : TESLA
– B Rin2 : Large/Huge Detector
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 37
Optimization for PFA
• Jet energy resolution– jet
2 = ch2 + 2 + nh
2 + confusion2 + threashold
2
– Perfect particle separation:
• Charged-/nh separation– Confusion of /nh shower with charged particles is the
source of confusion Separation between charged particle and /nh shower is important
– Charged particles should be spread out by B field– Lateral size of EM shower of should be as small as
possible ( ~ Rmeffective: effective Moliere length)
– Tracking capability for shower particles in HCAL is a very attractive option Digital HCAL
EEjet /%15~/
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 38
Merits and demerits of Large/Huge detector
• Merits– Advantage for PFA– Better pt and dE/dx resolution for the main tracker– Higher efficiency for long lived neutral particles (Ks, , and
unknown new particles)• Demerits
– Cost ? – but it can be recovered by• Lower B field of 3T (Less stored energy)• Inexpensive option for ECAL (e.g. scintillator)
– Vertex resolution for low momentum particles• Lower B requires larger Rmin of VTX because of beam
background (IP)~5 10/(psin3/2) m is still achievable using wafers of
~50m thick
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 39
Forward Detector components
• Si forward disks / Forward Calorimeter– Tracking down to cos=0.99– Luminosity measurement
• Beam calorimeter– Not considered in GLC detector – At ILC, background is 1/200. Need serious consideration– Careful design needed not to make back-splash to VTX– Minimum veto angle ~5mrad (?) Physics
• Si pair monitor– Measure beam profile from r-phi distribution of
pair-background– Radiation-hard Si detector (Si 3D-pixel)
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 40
Parameters comparedSiD TESLA GLD
Solenoid B(T) 5 4 3
Rin(m) 2.48 3.0 3.75
L(m) 5.8 9.2 9.86
Estored(GJ) 1.4 2.3 1.8
Main Tracker
Rmin (m) 0.2 0.36 0.4
Rmax(m) 1.25 1.62 2.0
BL2.5 5.7 7.1 9.7
m 7 150 150
Nsample 5 200 220
pt/pt2 3.6e-5 1.5e-4 1.2 e-4
6 Jan 2005 Mark Oreglia, SLAC MDI Workshop 41
Paramters (cont’d)SiD TESLA GLD
ECAL Rin (m) 1.27 1.68 2.1
BRin2 8.1 11.3 13.2
Type W/Si W/Si (W/Sci)
Rmeff (mm) 18 24.4 16.2
BRin2/Rm
eff 448 462 817
Z (m) 1.72 2.83 2.8
BZ2/Rmeff 822 1311 1452
X0 21 24 27
E+HCAL
5.5 5.2 6.0
t (m) 1.18 1.3 1.4