Overview of LC Detectors
Mark Oreglia, University of Chicago
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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
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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
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Cosmology “benchmarks” summarized:
“bulk” -> cc annihilation -> smuon/selectron
“coannihilation” -> c-stau annihil. -> staus
Low angle backgrounds
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Momentum Resolution
• e+e-gZHgll X
• Golden physics channel!
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d(1/p) = 7 x 10-5/GeV
• 1/10 LEP !!!
• goal: dMmm <0.1x GZ
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dMH dominated by
beamstrahlung
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Impact Parameter
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dd= 5 mm  10/p(GeV) mm
• 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
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(Jet) Energy Resolution
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dE/E = 0.3/ E(GeV)
<1/2 LEP !!!
DMDijet ~ GZ/W
separation between
e+e-gnnWWgnnqqqq and e+e-gnnZZgnnqqqq
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Mark Oreglia, SLAC MDI Workshop
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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
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Hermeticity
• hermetic down to q = 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
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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)
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~5% of power at 500 GeV
•
backgrounds
•
e+e- pairs
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radiative Bhabhas
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low energy tail of disrupted beam
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neutron “back-shine” from dump
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hadrons from gamma-gamma
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Mark Oreglia, SLAC MDI Workshop
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Time Structure:
5 Bunch Trains/s
Dtbunch=337ns
950 µs
199 ms
950 µs
2820 bunches
 Event rates: Luminosity: 3.4x1034 cm-2 s-1
e+e-gqq,WW,tt,HX 0.1 / train
(6000xLEP)
e+e-ggggX:~200 /Train
Background from Beamstrahlung:
6x1010 g/BX
140000 e+e-/BX + secondary particles (n,m)
 Large B field and shielding
But still: 600 hits/BX in Vtx detector
6 tracks/BX in TPC
E=12GeV/BX in calorimeters
E 20TeV/BX in forward cals.
High granularity of detectors
and fast readout for stable
pattern recognition and
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
event
reconstruction
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IR Issues
pairs
6 Jan 2005
Hits/bunch train/mm2 in VXD,
and photons/train in TPC
Mark Oreglia, SLAC MDI Workshop
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Beam Energy
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need to know <E>lumi-weighted
Some analyses require better than 0.1%
techniques for determining the lumi-weighted
<ECM>:
energy spectrometers
Bhabha acolinearity
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Other possibilities :
gZ, ZZ and WW events; use existing Z and W mass
utilize Bhabha energies in addition to Bhabha acol
m-pair events; use measured muon momentum
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200 ppm feasible; 50 ppm a difficult challenge
Top-mass:
need knowledge of E-spread
FWHM to level of ~0.1%
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Crossing Angle
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Mark Oreglia, SLAC MDI Workshop
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Summary of MDI Issues
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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
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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 g-g or e-g collisions
• Even worse low-angle background problems
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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There are currently 3 Detector Concepts
• The WorldWide Study is working on a plan:
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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
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Mark Oreglia, SLAC MDI Workshop
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Comparison of 3 Concepts
(thanks to Y. Sugimoto)
•Si tracking and ECAL
•Small R
•Smallest granularity
6 Jan 2005
•Moderate R
•TPC tracker
•SiW ECAL
Mark Oreglia, SLAC MDI Workshop
•Very large R
•Jet chamber or TPC
•Scintilator/W-Pb-Fe
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TESLA (and NA Large Det)
(Thanks to Ties Behnke, Mike Ronan, Markus Schumacher)
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Mark Oreglia, SLAC MDI Workshop
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Basic TESLA Detector Concept
Large gaseous central
tracking device (TPC)
High granularity
calorimeters
High precision
microvertex detector
All inside magnetic field
of 4 Tesla
No hardware trigger, dead time free
continous readout for complete bunch train (1ms)
Zero suppression, hit recognition and digitisation in FE electronics
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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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 d(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
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Vertex Detector: Conceptual Design
Impact parameter: sd ~R1 spoint
5 Layer Silicon pixel detector
•Small R1: 15 mm (1/2 SLD)
•Pixel Size:20x20mm2  sPoint =3 mm
•Layer Thickness: <0.1%X0
suppression of g conversions –
ID of decay electrons
minimize multiple scattering
800 million readout cells
Hit density: 0.03 /mm2 /BX at R=15mm
a pixel sensors
Read out at both ladder ends in layer 1:
frequency 50 MHz, 2500 pixel rows
acomplete readout in: 50ms ~ 150BX
<1% occupancy
no problem for track reconstruction expected
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Flavour Tagging
 Powerful flavour tagging techniques (from SLD and LEP)
Expected resolution in r,f and r,z
s ~ 4.2 4.0/pT(GeV) mm
e.g. vertex mass
M
l/sl
 charm-ID: improvement
by factor 3 w.r.t SLD
•LEP-c
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Mark Oreglia, SLAC MDI Workshop
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Gaseous or Silicon Central Tracking?
gaseous
e e
advantages of gaseous tracking:
many points
simple pattern recognition
redundancy
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H A
0
bbbb
silicon
“but be careful with these
comparisons!”
This is something of an
aesthetic argument
Mark Oreglia, SLAC MDI Workshop
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Forward Tracking
250 GeV m
FTD: 7 Disks
3 layers of Si-pixels 50x300mm2
4 layers of Si-strips srf= 90mm
FCH: 4 Layers
Strawtubes or Silicon strips
(double sided)
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Particle / Energy Flow
The energy in a jet is:
60 % charged particles:30 % g :10 %KL,n
Reconstruct 4-vectors of individual particles avoiding double counting
Charged particles in tracking chambers
Photons in the ECAL
Neutral hadrons in the HCAL
(and possibly ECAL)
need to separate energy deposits from different particles
• small X0 and
RMoliere
KL,n
: compact showers
• high lateral granularity D ~ O(RMoliere)
p
• large inner radius L and strong magnetic field
 Discrimination between EM and hadronic showers
• small X0/lhad
g
e
• longitudinal segmentation
Mark Oreglia, SLAC MDI Workshop
granularity more important
than energy resolution 23
6 Jan 2005
Calorimeter Conceptual Design
ECAL and HCAL inside coil
large inner radius L= 170 cm
 good effective granularity
Dx~BL2/(RM  D) 1/p
Dx distance between charged and
neutral particle at ECAL entrance
•ECAL: SiW,
•40 layers/24Xo/0.9lhad, 1cm2 lateral segmetation
• sE/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
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Forward Calorimeters
TDR version of mask L* = 3 m
Tasks:
Shielding against background
Hermeticity / veto
LAT: Luminosity measurement from Bhabhas (83 to 27 mrad)
SiW Sampling Calorimeter
aim for DL/L ~ 10-4 require Dq = 1.4 mrad
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
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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SiD Design Starting Point
(Thanks to Marty Breidenbach, John Jaros)
B = 5T
6 Jan 2005
Recal = 1.25m
Zecal = 1.74m
Mark Oreglia, SLAC MDI Workshop
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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…
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Limit Si/W calorimeter radius and length, to constrain cost
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Boost the B field to recover BR2 for particle flow, improve momentum
resolution for tracker, reduce backgrounds for VXD
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Use Si microstrips for precise tracking
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Mark Oreglia, SLAC MDI Workshop
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Cost (and physics) balance R and B
High Field Solenoid and Si/W Ecal are major 250.00
cost drivers.
Magnet Costs  Stored Energy 
(SiD ~1.1GJ  80-100 M$)
200.00
Cost
[M$]
Fix BR2=7.8, tradeoff B and R 
150.00
Linear
Power
Exp Data
100.00
50.00
0.00
Cost Partial, Fixed BR^2
0
70
1.85
60
1.75
0.5
1
1.5
2
2.5
3
3.5
4
Stored Energy [GJ]
50
Delta M$
1.65
Linear
40
1.55
30
Power
Radius
1.45
20
1.35
10
Delta M$ vs B, BR2=7.8 [Tm2]
0
0
1
2
3
4
5
1.25
6
B
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Mark Oreglia, SLAC MDI Workshop
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ECAL
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Mark Oreglia, SLAC MDI Workshop
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Si Detector/ Readout Chip
Readout ~1k pixels/detector
with 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
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Mark Oreglia, SLAC MDI Workshop
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HCAL
• Inside the coil
• Rin= 1.42m; Rout= 2.44m
• 4l Fe (or W, more compact)
2cm Fe, 1cm gap
• Highly segmented
1x1 cm2 – 3x3 cm2
~ 40 samples in depth
• Technology?
RPC
Scint Tile
GEM
S. Magill (ANL)
…many critical questions for the SiD Design Study:
thickness? Segmentation? Material? Technology?
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Silicon Tracking
Why silicon microstrips?
Robust against beam halo
SiD starting point
Thin, even for forward tracks.
Won’t degrade ECAL
Stable alignment and calibration.
Excellent momentum resolution
Dp/p2~2 x 10-5
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Mark Oreglia, SLAC MDI Workshop
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Tesla
VXD
SiD
0.2
0.15
0.1
0.05
0
-0.05
-0.1
-0.15
-0.2
Shorten barrel, add endcaps.
 Shorten Barrel CCDs to 12.5 cm (vs. 25.0cm)
 add 300 mm Si self-supporting disk endcaps
(multiple CCDs per disk)
This extends 5 layer tracking over max , improves forward
pattern recognition.
improve  Coverage, improve simpact 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
6 Jan 2005
0.05
0.1
0.15
0.2
0.25
Mark Oreglia, SLAC MDI Workshop
0.3
0.35
0.4
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SiD Subsystems
So 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 Tracking
Pixels or strips?
• Very Forward Cal (huge and active area!)
Active masks and vetoes
Lumcal
Beamcal (pair monitor)
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Global Large Detector
(Thanks to Y. Sugimoto)
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Mark Oreglia, SLAC MDI Workshop
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Basic design concept
•  Detector optimized for Particle Flow Algorithm (PFA)
• Large/Huge detector concept
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GLC detector as a starting point
Move inner surface of ECAL outwards to optimize for PFA
Larger tracker to improve dpt/pt2
Re-consider the optimum sub-detector technologies based on the
recent progresses
Different approaches
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B Rin2
: SiD
B Rin2
: Large/Huge Detector
B Rin2
6 Jan 2005
: TESLA
Mark Oreglia, SLAC MDI Workshop
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Optimization for PFA
• Jet energy resolution
– sjet2 = sch2 + sg2 + snh2 + sconfusion2 + sthreashold2
– Perfect particle separation:
• Charged-g/nh separation
s jet / E ~ 15% / E
– Confusion of g/nh shower with charged particles is the
source of sconfusion  Separation between charged particle
and g/nh shower is important
– Charged particles should be spread out by B field
– Lateral size of EM shower of g should be as small as possible
( ~ Rmeffective: effective Moliere length)
– Tracking capability for shower particles in HCAL is a very
attractive option  Digital HCAL
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Mark Oreglia, SLAC MDI Workshop
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Merits and demerits of Large/Huge
detector
• Merits
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Advantage for PFA
Better pt and dE/dx resolution for the main tracker
Higher efficiency for long lived neutral particles (Ks, L, and
unknown new particles)
• Demerits
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Cost ?
– but it can be recovered by
–
Vertex resolution for low momentum particles
• Lower B field of 3T (Less stored energy)
• Inexpensive option for ECAL (e.g. scintillator)
• Lower B requires larger Rmin of VTX because of beam background
 d(IP)~5  10/(pbsin3/2q) mm is still achievable using wafers of
~50mm thick
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
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Forward Detector components
• Si forward disks / Forward Calorimeter
– Tracking down to cosq=0.99
– Luminosity measurement
• Beam calorimeter
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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
background
– Radiation-hard Si detector (Si 3D-pixel)
6 Jan 2005
Mark Oreglia, SLAC MDI Workshop
pair-
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Parameters compared
Solenoid
Main
Tracker
6 Jan 2005
SiD
TESLA
GLD
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
Rmin (m)
0.2
0.36
0.4
Rmax(m)
1.25
1.62
2.0
BL2.5
5.7
7.1
9.7
s(mm)
7
150
150
Nsample
5
200
220
dpt/pt2
3.6e-5
1.5e-4
1.2 e-4
Mark Oreglia, SLAC MDI Workshop
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Paramters (cont’d)
ECAL
E+H
CAL
6 Jan 2005
SiD
TESLA
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/Rmeff
448
462
817
Z (m)
1.72
2.83
2.8
BZ2/Rmeff
822
1311
1452
X0
21
24
27
l
5.5
5.2
6.0
t (m)
1.18
1.3
1.4
Mark Oreglia, SLAC MDI Workshop
GLD
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