Transcript Document 7344607

SiD
Expectations from the Design Study
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Motivation
What We Need!
Technical efforts
Status
31 July 2004
SiD Design Study
M. Breidenbach
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SiD Motivation
• SiD is an attempt to interest the US HEP community, and
the international community, in the experimental challenges
of a LC.
• SiD represents an attempt to design a comprehensive LC
detector, aggressive in performance but constrained in cost.
• SiD attempts to optimize the integrated physics
performance capabilities of its subsystems.
• SiD might be considered a first step towards being one of
the two detectors at the LC, but its development is
substantially behind TESLA.
• SiD addresses warm technology advantages and challenges –
but could handle cold. We shall soon see!
• The design study should evolve the present concept of SiD
towards a more complete and optimized design.
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Nominal SiD Detector Requirements
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a) Two-jet mass resolution comparable to the natural widths of W and Z for an unambiguous
identification of the final states.
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b) Excellent flavor-tagging efficiency and purity (for both b- and c-quarks, and hopefully also for
s-quarks).
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c) Momentum resolution capable of reconstructing the recoil-mass to di-muons in Higgs-strahlung
with resolution better than beam-energy spread .
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d) Hermeticity (both crack-less and coverage to very forward angles) to precisely determine the
missing momentum.
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e) Timing resolution capable of tagging bunch-crossings to suppress backgrounds in calorimeter
and tracker.
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f) Very forward calorimetry that resolves each bunch in the train for veto capability.
– This is the standard doctrine – is it correct and complete?
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SiD (Silicon Detector)
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Conceived as a high performance detector for the LC
Reasonably uncompromised performance
But
Constrained & Rational cost
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Detectors will get about 10%
of the LC budget:
2 detectors,
so $350 M each
Accept the notion that excellent energy flow
calorimetry is required, and explore
optimization of a Tungsten-Silicon EMCal and
the implications for the detector
architecture…
This is the monster assumption of SiD (and
TESLA!)
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Crude Cost Breakdown
Management
Tracker
Install LumMon
VXD
Magnet
EMCal
HCal
Muons
Elecs
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Crude Cost Trends
Crude Cost vs BR^2
800
750
700
Crude Total Costs
650
600
B=5
550
B=4
700
500
B=3
650
450
M$
800
750
400
M$
600
550
B=5
B=4
350
500
B=3
300
0
10
20
450
30
40
50
BR^2
400
350
300
0
1
2
3
4
Tracking Radius (m)
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Architecture arguments
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Silicon is expensive, so limit area by limiting radius (and length)
Get back BR2 by pushing B (~5T)
Maintain tracking resolution by using silicon strips
Buy safety margin for VXD with the 5T B-field.
Keep track finding by using 5 VXD space points to determine track – tracker measures
sagitta.
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Knees
• During the SSC era, the SSC PAC asked the detector
collaborations to justify their design choices – where
possible by understanding the quality of detector
performance as a function of a critical detector parameter.
Ideally, quantities like overall errors on an important physics
process would flatten out as a function of, say, calorimeter
resolution, and there would be a rational argument for how
good the resolution should be.
• We need similar analyses for the major parameters of SiD –
EMCal radius and B are probably at the top of the list, along
with justifying E-Flow calorimetry.
• We need to select physics processes for this study.
• We are not constrained to design detector around these
knees, but we should know where they are!
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SiD Configuration
Quadrant View
8.000
Beam Pipe
Ecal
7.000
Hcal
Coil
6.000
MT
Endcap
Endcap_Hcal
5.000
m
Endcap_Ecal
VXD
4.000
Track Angle
Endcap_Trkr_1
3.000
Endcap_Trkr_2
Endcap_Trkr_3
2.000
Endcap_Trkr_4
Endcap_Trkr_5
Trkr_2
1.000
Trkr_3
0.000
0.000
Trkr_4
2.000
4.000
m
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6.000
8.000
Trkr_5
Trkr_1
Scale of EMCal
& Vertex Detector
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Tesla
Vertex Detectors
SiD
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
Extend 5 layer tracking over max Ω
improve Ω Coverage, improve σxy, σrz
5 CCD layers
.97
(vs. .90 TDR VXD)
4 CCD layers
.98
(vs. .93 TDR VXD)
Minimize CCD area/cost
 Shorten Barrel CCDs to 12.5 cm (vs. 25.0cm)
Thin the CCD barrel endplate
 a single 300 μm Si disk for self supporting
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Design CCD’s for
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Optimal shape ~2 x 12 cm
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Multiple (~18) ReadOut nodes for fast readout
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Thin -≤ 100 µ
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Improved radiation hardness
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Low power
Readout ASIC
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No connectors, cables, output to F.O.
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High reliability
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Increased RO speed and lower power compared to SLD VXD3
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Detailed (preliminary) spec coming along…
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Vertex Detector Questions
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The beam pipe could be made very thin with some serious engineering – Does the physics justify the
effort?
The CCD’s could probably be thinned to ~50 μm – Does the physics justify the effort?
The CCD’s could probably be supported by stretching from their ends – same question.
The present nominal radius of the beampipe is 1.0 cm. This is probably a stretch for the machine. Is
it justified?
The preliminary impression is that the answers are No! They need work!
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Silicon Tracker
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SLC/SLD Prejudice: Silicon is robust against machine mishaps; wires & gas
are not.
Silicon should be relatively easy to commission – no td relations, easily
modeled Lorentz angle, stable geometry and constants.
SiD as a system should have superb track finding:
– 5 layers of highly pixellated CCD’s
– 5 layers of Si strips, outer layer measures 2 coordinates
– EMCal provides extra tracking for Vee finding - ~1mm resolution!
Simulation Studies:
– Pattern recognition (S. Wagner, N. Sinev)
– Occupancies (T. Maruyama)
– γγ backgrounds (T. Barklow)
– Geometry optimization (R. Partridge - Brown)
– All studies so far are encouraging. (Note very forward rates are high,
and required segmentation is not yet designed.
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Illustration of bunch timing tag
Yellow = muons
full train (56 events)
454 GeV detected energy
100 detected charged tracks
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Red = electrons
Green = charged pions
Dashed Blue = photons with E > 100 MeV
1 bunch crossing
T. Barklow
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First attempt - Make Structure of Long Ladders
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Readout half ladders from
ends.
Wire bond 10 cm square
detectors in daisy chain as
in GLAST.
Minimal electronics and
power pulsing make gas
cooling easy. No liquids,
leaks or associated mass.
Problems:
– Timing tag seems
impossible.
– Occupancies forward
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Evolve!
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Ditch (romantic) notion of long ladders and read out each detector.
Detector has signals routed to rectangular grid for bump bonding to
detector, analogous to design for Si-W Calorimeter.
Bunch separation timing capability, better segmentation and occupancy,
better S/N.
Replace individual ladders with composite, monolithic cylinder with
detectors mounted to surface.
Bypass Caps
Strip Detector
Thin Kapton Cable
Readout Chip
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Thickness Budget (Rough!)
Material
Thickness (Microns)
Thickness
Radiation Lengths (%)
Silicon
300
0.32
Kapton
70
0.02
Copper
20
0.14
Carbon (Structural support)
500 (average)
0.27
Total
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0.75
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Momenter Questions
• Are there any serious problems with track finding (using
VXD & EMCal)? (Barrel is 5 axial layers, segmented ~13 cm.)
• Is the 1.25 m radius optimal? What about the length?
• Is 5 T B optimal?
• Is there motivation to try to go thinner? Is there a knee in
the physics performance vs multiple scattering?
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SiD EMCal Concept
Longitudinal
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Wafer and readout chip
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SiD Si/W Features
Current configuration:
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~1000 “channels” per readout chip
Compact – thin gap ~ 1mm
– Moliere radius 9mm → 14 mm
Cost nearly independent of transverse segmentation
Power cycling – only passive cooling required
Dynamic range OK
BunchTiming in design
– Low capacitance
– Good S/N
– Correct for charge slewing/outliers
– 5 ns σ per (independent) measurement
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• 5 mm pixels
• 30 layers:
•20 x 5/7 X0 +
•10 x 10/7 X0
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Components in hand
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Tungsten
Rolled 2.5mm
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1mm still OK
Very good quality
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< 30 μm variations
92.5% W alloy
Pieces up to 1m long possible
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Silicon
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Hamamatsu detectors
Should have first lab measurements
soon
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EMCal Questions
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Is an (expensive) Si-W tracking EMCal justified by the physics? Does EFlow really work? It gives good but not great energy resolution – what about
an EMCal with crystals with superb energy resolution? Crystals with some
longitudinal segmentation?
Is there a useful Figure of Merit for E-Flow calorimetry? (My present
favorite is BR2/{(σmeffσpixel)2x(σmeff rsamp)}
Is radius of 1.25 m optimal? Is 5T B optimal? Same question as before!
Are there E-Flow performance issues in the forward direction? Are the end
EMCals far enough from the IP?
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HCal Assumptions and Questions
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HCal assumed to be 4 l thick, with 34 layers 2 cm thick alternating with 1
cm gaps. Is 4 l right? What about layer thickness?
Need large area of inexpensive detectors. e.g. high reliability RPC’s (Have
they been invented yet???) Probably glass RPC. GEM’s??? Other??? Note
that digital – analog is a non-issue for us.
HCal radiator non-magnetic metal – probably stainless. Is iron the right
material?
Hcal thickness important cost driver, even though HCal cost small. And
where is it relative to coil?
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HCal Location Comparison
Hcal Delta Cost
2l
90.0
80.0
Scale –
Relative
to 4 l
Inside!!
70.0
60 M$
Delta M$
60.0
50.0
40 M$
40.0
30.0
20 M$
20.0
10.0
0 M$
0 M$
0.0
-30 M$
0.0
0.0
1.0
2l
2.0
4l
3.0
4.0
5.0
HCal Lam da
6l
6.0
5.0
6.0
7.0
-15.0
-20.0
-25.0
-30.0
Quadrant View
7.000
5.000
4.000
Coil
2.000
1.000
Beam Pipe
Trkr
Ecal
Hcal
Coil
MT
Endcap
Endcap_Hcal
Endcap_Ecal
VXD
Endcap_Trkr
6.000
5.000
m
Beam Pipe
Trkr
Ecal
Hcal
Coil
MT
Endcap
Endcap_Hcal
Endcap_Ecal
VXD
Endcap_Trkr
6.000
m
4.0
HCal Lam da
7.000
4.000
3.000
2.000
Coil
HCAL
outside
coil
1.000
2.000
4.000
m
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3.0
-35.0
8.000
0.000
0.000
2.0
7.0
8.000
3.000
1.0
-10.0
Quadrant View
Hcal
inside
coil
6l
-5.0
-10 M$
-20 M$
4l
Hcal Delta Cost
0.0
Delta M$
80 M$
6.000
8.000
0.000
0.000
2.000
4.000
6.000
8.000
m
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Coil and Iron
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Solenoid field is 5T – 3 times the field from detector coils that have been used in the
detectors. - CMS will be 4T.
Coil concept based on CMS 4T design. 5 layers of superconductor about 72 x 22 mm, with
pure aluminum stabilizer and aluminum alloy structure. The aluminum alloy structural strips
are beefed up relative to CMS.
Coil Dr about 85 cm
Stored energy about 1.5 GJ (for Tracker Cone design, R_Trkr=1.25m, cosqbarrel=0.8).
(TESLA is about 2.4 GJ)
[Aleph is largest existing coil at 130 MJ]
Is 5T right? And is it buildable? We need a “pre-conceptual” design!
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Br
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Bz
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Flux Return/Muon Tracker
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Flux return designed to return the flux! Saturation field assumed to be 1.8
T, perhaps optimistic.
Iron made of 5 cm slabs with 1.5 cm gaps for detectors, again “reliable”
RPC’s.
Does the flux really need to be returned?
Are 5 cm slabs ok?
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More Cost trade-offs
Caveat: Based on Si @ $6/cm2, W @
$100/Kg.
Cost Partial R_Trkr
Cost Partial, Fixed BR^2
180.0
160.0
70
1.85
60
1.75
140.0
50
1.65
Delta M$
Delta M$
120.0
100.0
Linear
40
1.55
30
Radius
1.45
80.0
20
60.0
10
1.35
0
40.0
1.25
0
1
2
3
4
5
6
B
20.0
0.0
0.5
0.75
1
R_Trkr (m )
D$ vs R_Trkr
~1.8M$/cm
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1.25
Power
1.5
Delta $, Fixed BR2=5x1.252
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Not Worried about yet
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Small angle systems
Vibration Control
Crossing angle correctors
And others!
• All are important, and must be done “right” but unlikely to be
design drivers in the class with E-Flow, B, Rcal.
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Timing Analysis!
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2015 Begin Operation ???
6 years construction - 2009
3 years serious R&D - 2006
2 years – conceptual design, including first critical rounds of
testbeam work!!!
- 2004 [~now??]
• We need answers to these questions to get to a credible
conceptual design!
• We need answers to these questions to compare
performance with the TPC based detectors!
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