The International Linear Collider:
The Physics and its Challenges
Harry Weerts
Argonne National Lab
UTA, September 20, 2006
R&D
Outline
Introduction: personal
Particle Physics: status & future
History, Matter & Interactions;
US program and worldwide program
Open questions
Future Program and Open Questions
ILC Physics
The ILC: the machine challenges
The ILC : the detector challenges
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Intro: personal
Hadron collider physics with Dzero experiment ( MSU, Fermilab)
Since inception, >20 years
Needed something new before retirement……
“Decided” ILC needs senior involvement
Young people busy &
not good for them
Spent sabbatical 2004-2005 at Fermilab.
Learnt a lot, machine & detectors, a
lot of progress on ILC that year
Time scales a concern in HEP
Work on ILC only.
Technology decision; GDE
formed, started on detector
concept study, Snowmass
2005
Well into ILC, also changed positions,
By Sept 2005: strengthen & define ILC program at Argonne
(Management & ILC)
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State of HEP/Particle Physics
Immense progress over last 40 years
Theory
Experiments
Fixed target
Dynamics based on (non)-abelian,
local gauge invariance, led to
unification of forces: EM and
weak, strong
Beams: e,m,p,p,n
Higher energy:
colliding beams
Standard Model, with detailed
predictions, but also open
questions
strong feedback
ee, pp , ep
Strong, competing & complementary accelerator based experimental programs
around world:
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1
How did we learn this…
Fixed Target
beams
protons, muons,
neutrinos,etc
2
target
detector
Colliding beams
Gargamelle in neutrino beam
proton
antiproton
electron
proton
positron
detector
Increasing energy probes smaller and smaller
distances
5
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Dzero event at Tevatron
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Status of Particle Physics (1)
Described by Standard Model
All matter made up of fermions (
quarks & leptons)
Interactions/forces between them
mediated by bosons
Understood at such a level that ALL
interactions/cross sections can be well
calculated and simulated
Very good predictive power
(verified by experiment)
at energies reachable today
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Status of Particle Physics (2)
Interactions/Forces
Fermions make up all
known matter
(more detail)
Electromagnetic =
+
Strong (QCD) =
=
All of “day to
day” matter
Weak =
Nuclear reactors
= neutrino industry;
Flavor Oscillations
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“Problems” with the Standard Model (I)
The Standard Model predicts/requires at
least one more field  Higgs
Part of symmetry breaking, resulting in SM
So far not observed  problem
To keep Higgs mass finite, avoid divergences in scattering
(WW) need additional symmetries i.e. fields i.e. particles
Possible solutions:
Supersymmetry (SUSY), extra dimensions, plus ++
Particles are being searched for 
out of energy range accessible now
( need for higher energy)
(experiment: m > ~250 Gev/c)
Unexplained:
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•Mass hierarchy
•Neutrino oscillations
•Matter-antimatter asymmetry in universe
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Missing parts
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Problems (2)
Astro physical observations
Cosmic microwave background, rotation
curves of galaxies point to need for
Dark Matter
Accelerated expansion of universe
point to need for
Dark Energy
Additional “missing” fields/particles
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Observations from universe ( large scale)
Questions about universe:
Where is anti matter ?
Most mass in universe not in SM particles
So ONLY 4% of universe consist of particles we know.
A lot left to identify…..
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State of knowledge of universe…
The “Iceberg” picture of
our understanding of
universe.
Next step is to address
this at accelerators and
find the corresponding
particles and understand
what dark matter and
energy are
Connect cosmic scale to
particle scale
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Particle Physics accelerators
1990
Interplay needed:
LEP<-> Tevatron
HERA<-> Tevatron
HERA<-> LHC
Tevatron <-> Babar
1995
LEP I
135
175
5
Run II
2000
2005
161.3
172 183 189 196-200
2010
LEP
few
world
pb- 1
10+10 55 175
SLC
Run II (2TeV)
Run I (1.8TeV)
pb- 1
110
Tevatron
fb- 1
2-> 4 -> ?
e -p
e +p
ILC
HERA
pb- 1
47
RHIC pp
CESR
LHC (14TeV)
BaBar, Belle, HERA-B
B factories
1990
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1995
LHCb
empty
US
2000
12
2005
now
2010
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The future I; will happen
R&D
The first BIG step in understanding
Higgs and “Iceberg” will the
Mont Blanc
Massif
Large Hadron Collider (LHC) at CERN
ATLAS
Ready for
1st beam
end 2007.
LHC
Detector scale
15 year program
Proton-proton collisions at 14 TeV; expect lots of new physics & discoveries
LHC is discovery machine
Find new/unexplained phenomena & particles
Will be very difficult( impossible….) to
distinguish different physics models/theories
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(ILC)
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LHC potential and need for ILC
one
page
The Large Hadron Collider (LHC), will open window to
“remainder” of and physics “beyond” the Standard Model.
Starting
This is the energy/mass regime
in
from ~0.5Tev to a few TeV
2007…..
LHC
Completing the Standard Model and the symmetries underlying it
plus their required breaking leads us to expect a plethora of new
physics.
new particles and fields in this energy range
LHC will discover them or give clear indications that they exist.
We will need a tool to measure precisely and unambiguously their
properties and couplings i.e. identify physics.
This is an e+e- machine with a centre of mass
energy starting at 0.5 TeV up to several TeV
ILC
Starting next decade
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Difference in “energy frontier” experiments (ee)
Two main kind of machines:
1)electron –positron ( e+e- annihilation) colliders
2)proton-(anti)proton collider ( Tevatron, future LHC)
e+e- annihilation:
Total energy of e+ and e- available as Ecms or s
Scan over resonances
Maximum achieved for Ecms =192 GeV
Energy range
covered by
e+e- colliders
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Very clean environment; precision physics
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ILC: Physics Event Rates
s-channel processes through
spin-1 exchange: s ~ 1/s
Cross sections relatively
democratic:
s (e+e-  ZH) ~
0.5 * s(e+e-  ZZ)
Cross sections are small;
for L = 2 x 1034 cm-2s-1
e+e-  qq, WW, tt, Hx
~ 0.1 event /train
e+e-  e+e- gg  e+e- X
~ 200 /train
Beyond the Z, no resonances
W and Z bosons in all decay
modes become main objects
to reconstruct
Need to reconstruct final states
Forward region critical
Highly polarized e- beam: ~ 80%
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ILC Physics Characteristics
Cross sections above Z-resonance are very small
s-channel processes through spin-1 exchange
Highly polarized e- beam: ~ 80%
ds ff

3 tot
 s ff (1  Pe Ae )(1  cos 2  )  2(Ae  Pe )Af cos 
d cos  8
2 gVf g Af
Ab  0.94 A c  0.67 Al  0.15
Af  2
g Vf  g 2 Af
Hermetic detectors with uniform strengths
HZ  qqll
MH = 120 GeV

Errors correspond to 20 fb-1
Importance of forward regions
b/c tagging and quark identification
Measurements of spin, charge, mass, …
Analyzing power of
Scan in center of mass energy
Various unique Asymmetries
Forward-backward asymmety
Left-Right Asymmetry
 Largest effects for b-quarks
Identify all final state objects
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What should ILC detector be able to do ?
Identify ALL of the constituents that we know & can be
produced in ILC collisions & precisely measure their properties.
u,d,s jets; no ID
c, b jets with ID
t final states; jets +
W’s
n’s: missing energy; no
ID
e, m: yes
t through decays
g ID & measure
gluon jets, no ID
W,Z leptonic &
hadronic
Use this to measure/identify the NEW physics
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Examples of accelerators
Linear accelerator (LINACs)
Circular accelerator ( synchrotron)
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The Machine
pre-accelerator
few GeV
source
KeV
damping
ring
few GeV
few GeV
bunch
compressor
250-500 GeV
main linac
extraction
& dump
final focus
IP
collimation
Enormously challenging with many different components, but …
Polarized electron and positron source & damping rings
Main accelerator structure
Beam Delivery system
...
At end of accelerator need detector system to extract the physics from
the collisions. Needs to be a precision tool able to live within IP
environment.
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The International Linear Collider
Baseline Machine:
ECM of operation 200 – 500 GeV
Luminosity and reliability for 500 fb-1 in 4 years
Energy scan capability with <10% downtime
Beam energy precision and stability below 0.1%
Electron polarization of >80%
Two interaction regions with detectors
ECM down to 90 GeV for calibration
Upgrades:
ECM about 1 TeV
Capability of running at any ECM < 1 TeV
L and reliability for 1 ab-1 in 3 – 4 years
Options:
Extend to 1 ab-1 at 500 GeV in ~2 years
As defined in
e-e-, gg, e-g operation
e+ polarization ~ 50%
Giga-Z with L = several 1033 cm-2s-1
International Scope Document
WW – threshold scan with L = 1033 cm-2s-1
See www.fnal.gov/directorate/icfa/LC_parameters.pdf
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Baseline Configuration--Schematic
What is the ILC ?
500 GeV CM
Double energy
Given accel: ~35MV/m this implies large footprint
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Scope of the ILC 500GeV
Main linacs length ~ 21 km, 16,000 RF cavities (total)
RF power ~ 640 10-MW klystrons and modulators (total)
Cryoplants ~ 11 plants, cooling power 24 kW (@4K) each
Beam delivery length ~ 5 km, ~ 500 magnets (per IR)
Damping ring circumference ~ 6.6 km, ~400 magnets each
Beam power ~ 22 MW total
Site power ~ 200 MW total
Site footprint length ~ 47 km (for future upgrade > 1 TeV)
Bunch profile at IP ~ 500 x 6 nm, 300 microns long
Challenging to say the least
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ILC time line
R&D
2005
2006
2007
2008
2009
2010
Global Design Effort
Project
Baseline configuration
Reference Design
Technical Design
ILC R&D Program
Expression of Interest to Host
International Mgmt
Pursued by a design team that is global: from all regions of world
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Pictures/drawings…..
RF cavities
Two tunnel layout
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Cost Breakdown by Subsystem
cryo operations
4%
4%
instrumentation
2%
controls
4%
cf
31%
vacuum
4%
Civil
magnets
6%
installation&test
7%
systems_eng
8%
structures
18%
rf
12%
SCRF Linac
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TESLA SCRF cavity
~1m
9-cell 1.3GHz Niobium Cavity
Reference design: has not been modified in 10 years
Cavities have been produced in industry in EU & tested at DESY.
Challenge: produce in other parts of world in industry & develop
critical processing procedures.
Major worldwide goal: make cleaning and resulting gradient
consistent.
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Cavity fabrication
Niobium sheets are
formed into half
cavities
Cleanliness of surfaces is critical during process
Form into cavities with
electron beam welding (
need experience)
Currently many step process
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single-cell measurements (in nine-cell cavities)
Gradient
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Results from
KEK-DESY
collaboration
must reduce
spread (need
more statistics)
goal
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SMTF long term goals
Goal for 2006…. produce 1 full working cryo module
9 cell cavity
Initial cavities
will come from
DESY, KEK
Expect first 4
cavities from
industry next
year
Cryo module with 8 cavities
Goal:
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By 2009 have built 6-7 cryomodules; finalized design;
ready to built all components in industry.
Shows the need and long time scale for R&D
and industrialization
of process
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Image of a real cryomodule at DESY
Cryomodule with only 4 cavities.
A cryomodule with 8 nine cell cavities has not been produced yet.
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Site selection; Civil site studies
Design to “sample sites” from each region
Americas – near Fermilab
Japan
Europe – CERN & DESY
Americas Site - in Illinois– location may
vary from the Fermilab site west to near
DeKalb
Design efforts ongoing at Fermilab and
SLAC
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ILC in Illinois
my house
Source: Daily Herald
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Why ILC detector R&D ?
ILC
From a naïve perspective looks
like simple problem
bunch spacing
#bunch/train
Extrapolating from LHC
length of train
#train/sec
337 nsec
2820
950 msec
5 Hz
train spacing
199 msec
crossing angle
0-20 mrad ( 25 for gg)
But there are other factors which require better performance…..
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What should ILC detector be able to do ?
Identify ALL of the constituents that we know & can be
produced in ILC collisions & precisely measure their properties.
u,d,s jets; no ID
c, b jets with ID
t final states; jets +
W’s
n’s: missing energy; no
ID
e, m: yes
t through decays
g ID & measure
gluon jets, no ID
W,Z leptonic &
hadronic
Use this to measure/identify the NEW physics
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Backgrounds
“At the ILC the initial state is well defined, compared to LHC, but….”
Backgrounds from the IP
Disrupted beams
Extraction line losses
Beamstrahlung photons
e+e- - pairs
s (GeV)
Beam
# e+ e per BX
Total Energy
(TeV)
500
Nominal
98 K
197
1000
Nominal
174 K
1042
Backgrounds from the machine
Muon production at collimators
Synchrotron radiation
Neutrons from dumps,
extraction lines
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~ 20 cm
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~ 12 m
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Momentum resolution
Benchmark measurement is the measurement of the
Higgs recoil mass in the channel e+e- → ZH
Higgs recoil mass resolution improves until
∆p/p2 ~ 5 x 10-5
Sensitivity to invisible Higgs decays, and purity
of recoil-tagged Higgs sample, improve accordingly.
Example:
 s = 300 GeV
 500 fb-1
 beam energy spread of
0.1%
Goal:
 dMll < 0.1x GZ
Illustrates need for superb momentum resolution in tracker
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Jet energy resolution
Many processes have W and Z bosons in the
final state; events need to discriminate
Need for precision calorimetry
e+e- → WWnn, WZen and ZZnn events
Can be indicative of strong EWSB
60%/√Ejet
Goal for now is: 30%/√Ejet
30%/√Ejet
Both UTA and Argonne groups
heavily involved in this R&D
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Equivalent to
needing 40-200%
more luminosity
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Design Driver for any ILC detector
To be able to achieve the jet resolution
can NOT simply use calorimeters as
sampling devices.
sE
E
 0.30
1
E (GeV )
Have to use “energy/particle flow”. Technique has been used to
improve jet resolution of existing calorimeters.
Algorithm:
• use EM calorimeter ( EMCAL) to measure photons and electrons;
• track charged hadrons from tracker through EMCAL,
• identify energy deposition in hadron calorimeter (HCAL) with charged
hadrons & replace deposition with measured momentum ( very good)
• When completed only E of neutral hadrons ( K’s, Lambda’s) is left in
HCAL. Use HCAL as sampling cal for that.
Require:
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Imaging cal ( use as tracker = like bubble chamber),
 very fine transverse & longitudinal segmentation
Large dynamic range: MIP…. to …..shower
Excellent EM resolution
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Event
Event
display to
illustrate
granularity
Display
More detail
r-> p+po
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Some Detector Design Criteria
Requirement for ILC
Compared to best performance to date
Impact parameter resolution
Need factor 3 better than SLD
s r  s rz  5 10 /( psin 3/ 2  )
s r  7.7  33 /( psin 3 / 2  )
Momentum resolution
 1
 pT
s 
Need factor 10 (3) better than LEP
(CMS)

  5 105 (GeV 1 )

Need factor 2 better than ZEUS
Jet energy resolution goal
sE
E

sE
30%
E
E
Need factor ~200 better than LHC
Need factor ~20 smaller than LHC
Need factor ~10 less than LHC
Need factor ~ >100 less than LHC
Calorimeter granularity
Pixel size
Material budget, central
Material budget, forward
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60%
E
Detector implications:
Detector implications:
Observation:

LHC: staggering increase in scale, but modest extrapolation of performance
ILC: modest increase in scale, but significant push in performance
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Hadron Calorimetry
Role of hadron calorimeter in context of PFA is to measure neutrals
HCAL must operate with tracking and EM calorimeter as integrated system
Various Approaches
Readout
Analog readout -- O(10) bit resolution
Digital readout -- 1-bit resolution (binary)
Technolgoy
Active
 Resistive Plate Chambers
 Gas Electron Multipliers
 Scintillator
Passive
 Tungsten
 Steel
PFA Algorithms
Spatial separation
Hit density weighted
Gradient weighted
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Current simulated
performance of PFA
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Detector Concepts
“4th “
Different: no PFA;
solenoid arrangement
These detector concepts studied worldwide, with regional concentrations
Recently submitted “Detector Outline Documents” (~150 pages each)
Physics goals and approach all similar. Approach of “4” different
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Detector R&D efforts & Design Studies
R&D
Vxd
4-5
SiLC
SiD
X
X
LDC
X
X
X
X
GLD
X
?
X
X
Fwd
trac
Fwd
cal
SiD
X
X
LDC
X
X
GLD
X
X
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T
P
C
J
e
t
Fwd
Cher
Calice
EM
Calic
e
HAD
X
X
X
X
X
DA
Q
gg
BDI
R
X
X
?
X
X
?
X
X
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LC
cal
Cal
Asia
EM
OR/
SLAC
EM
hybrid
muon
X
X
X
X
X
X
X
X
X
X
X
X
Nearly all detector R&D efforts
are represented in the Design
Studies (DS)
R&D efforts with
concentration in Europe
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ILC detector funding worldwide
From WWS R&D panel report
Urgent R&D support levels over the next 3-5 years, by funding country or region. 'Established' levels are what people think
they get under current conditions, and 'total required' are what they would need to establish proof-of-principle for their
project.
Example:
US groups part of worldwide “Calorimeter” R&D (CALICE), but
can not fulfill commitments, because of lack of funding: EM &
HAD calorimeter efforts with testbeam (proof of principle)
Efforts underway to increase support in US for detector R&D
as part of total US ILC R&D funding
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Conclusions
The linear collider effort is gaining momentum, worldwide & in US
The community has decided the ILC to be the next highest priority
US community endorses that point of view and would like to host the ILC
Decision whether to build, depends on LHC results & price tag of ILC
Need substantial R&D over next 4-5 years to enable accelerator &
detector technologies; Scale is ~ $100M/year.
Current recommendations from P5 ( priorities in US HEP) are
to fund R&D needs of ILC in US.
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R&D
Backup slides
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R&D
Solenoid
Design calls for a solenoid with B(0,0) = 5T (not done previously)
Clear Bore Ø ~ 5 m; L = 5.4 m: Stored Energy ~ 1.2 GJ
For comparison, CMS: 4 T, Ø = 6m, L = 13m: 2.7 GJ
Stored Energy/Cold Mass [MJ/MT]
HEP Detector Superconducting Solenoids
SiD Coil
14
CMS
12
SiD
SDC Proto
10
Tesla
CMS 3.5
8
Atlas
6
CDF
D0
4
ISR
Aleph
Topaz
Babar
Venus
2
Zeus
Cleo II
GEM
H1
AMY
Delphi
0
1
SDC
10
Operating
100
Stored Energy [MJ]
1000
10000
Forseen
Full feasibility study (with CERN, Saclay) of design based on CMS
conductor
Start with CMS conductor design, but increase winding layers from 4 to 6
I(CMS)= 19500 A, I(SiD) = 18000 A; Peak Field (CMS) 4.6 T, (SiD) 5.8
Net performance increase needed from conductor is modest
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Testbeam for ILC
Proposal for multi-year testbeam program for study of high performance
calorimeters for the ILC with the CALICE collaboration at Fermilab
Summer 2006: Muon system tests, RPC tests
Fall 2006: Muon Tailcatcher and RPC readout (slice tests)
tentative: summer 2007: CALICE full 1 m3 EM and HCAL (scint + RPC)
Testbeam layout
Strong commitments, but limited
funding for US partners:
Tail Catcher
HCAL
Electronic
Racks
NIU/ANL/UTA/Iowa/UoC:
analog/digital hadron calorimetry
SLAC/Oregon/BNL: EMCAL
Tracking & Vertex tests
NIU tailcatcher: designed
and built by Fermilab
ECAL
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Beam
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World Wide Study R&D Panel
The World Wide Study Organizing Committee has established the Detector R&D
Panel to promote and coordinate detector R&D for the ILC. Worldwide activities at:
https://wiki.lepp.cornell.edu/wws/bin/view/Projects/WebHome
ILC detector R&D needs: funded & needed
Urgent R&D support levels over the next 3-5 years, by subdetector type. 'Established' levels are what people think they
will get under current conditions, and 'total required' are what they need to establish proof-of-principle for their project.
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Tracker Design
Baseline configuration
Cylinders are tiled with 10x10cm2
modules with minimal support
Material budget 0.8% X0/layer
z-segmentation of 10 cm
Active volume, Ri=0.218 m, Ro=1.233 m
Maximum active length = 3.3 m
Single sided in barrel; R,  in disks
Overlap in phi and z
Nested support
Power/Readout mounted on
support rings
Disks tiled with wedge detectors
Forward tracker configuration to
be optimized
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Hadron Calorimeter
Current baseline configuration for SiD:
Digital calorimeter, inside the coil
Ri = 139 cm, Ro =237 cm
Thickness of 4l
38 layers of 2.0cm steel
One cm gap for active medium
Readout
RPC’s as active medium (ANL)
1 x 1 cm2 pads
All options being explored
Pick-up pads
Graphite
Signal
HV
Resistive plates
Gas
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Particle Flow
Cluster finding, …
Physics
Dependence on environment
Minimum Spanning Tree
H-matrix + nearest neighbor
Hadrons
Algorithms
Algorithm
Institution
Iowa
g
Area of intensive work, not just
within SiD, but in whole ILC
community
Many, many open issues
ANL, KU, SLAC
Minimum Spanning Tree
Iowa
Hit Density-weighted
ANL
Spatial Density-weighted
NIU
Directed Tree cluster
NIU
NN based
Missing neutrinos, FSR, …
Divisive
Detector
Linearity, e/p, E-resolution, granularity
Sampling fluctuations, leakage, …
ANL, SLAC
FNAL
Fermilab Wine and Cheese, December 2 by Jose Repond
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Calorimeter Tracking
With a fine grained calorimeter, can do tracking with the calorimeter
Track from outside in: K0s and  or long-lived SUSY particles, reconstruct V’s
Capture events that tracker pattern recognition doesn’t find
Layer 2
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R&D
Muon System
Muon System Baseline Configuration
48 layers, 5 cm thick steel absorber plates
RPC’s as active medium
Muon ID studies done to date with 12
instrumented gaps with ~1cm spatial resolution
6-8 planes of x, y or u, v upstream of Fe flux
return for xyz and direction of charged
particles that enter muon system.
Muon
Technologies
RPC’s of glass and bakelite
Scintllators with photo-detection
GEM’s
Wirechambers
Hcal Ecal
trackers
Coil
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Calorimetry: PFA and Readout
Algorithm effort to look at particle flow and associated algorithms from a
fresh perspective
Figure of merit for PFA’s
decouple linearity, EM/HAD, response, calibrations
Fundamental limitations of energy resolution
Alternative approach to algorithm
grow clusters
split clusters
Readout chip for Digital HCAL; Prototype chip in hand
For Fermilab testbeam in 2007 to prove DHCAL
concept
1 m3, 400,000 channels, with RPC’s and GEM’s
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pipeline
64 channels/chip; 1 cm x 1 cm pads
Detector capacitance: 10 to 100 pF
Smallest input signals: 100 fC (RPC), 5 fC (GEM)
Largest input signals: 10 pC (RPC), 100 fC (GEM)
Adjustable gain; Signal pulse width 3-5 ns
Trigger-less or triggered operation
100 ns clock cycle
Serial output: hit pattern + timestamp
32
inputs
32
inputs
UTA, Sept 20, 2006
R&D
Testbeam
Testbeam facility at MT6 set up, commissioned and supported
Beam parameters:
Momentum between 4 and 120 GeV
protons, pions, muons, electrons
Usage:
14 MoU’s, 8 completed
MTBF
 BTeV Hybrid Pixels (FNAL)
 Belle MAPS (Hawaii)
 CMS Pixels (NU, Purdue)
 DHCAL (NIU, ANL)
Design study initiated to improve
the beamline at MTest to better
meet the requirements of the ILC community
Particle flow calorimetry is a linchpin for ILC physics
To date, PF not a proven concept based on Monte Carlo simulations
Fermilab could nucleate around the testbeam to form an intellectual
center and be a host for developing detector technologies for the ILC
There are many natural synergies …
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UTA, Sept 20, 2006
R&D
Particle Accelerators …..
Have played significant & critical role in particle physics
Laboratories worldwide built around them
Berkeley, Argonne,
Brookhaven, Stanford,
There two kinds of accelerators:
Fermilab, CERN, DESY
Linear accelerators (LINACs)
Applying alternating
E-field(RF)  accelerate
RF cavity
Basic accel.
structure
Circular accelerators
Synchrotrons (now)
Cyclotrons (initially)
Magnets ( ramped)
keep particles on path,
passage through RF
cavity increases energy
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H.Weerts
Layout
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Machine Parameters
Time structure: five trains of 2820 bunches per second
bunch separation is 307.7 ns (LEP: 22 ms)
868 ms
199 ms
http://www-project.slac.stanford.edu/ilc/acceldev/beamparameters.html
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868 ms
ECMS [GeV]
500
1000
L (cm-2s-1)
2.0 1034
3.0 1034
Bunches/Train
2820
2820
Bunch train length (ms)
868
868
Rep Rate [Hz]
5
5
Tsep (ns)
307.7
307.7
Gradient (MV/m)
30
30
N/bunch
2.0 1010
2.0 1010
sx, sy (nm)
655, 5.7
554, 3.5
sz (mm)
150
300
Θcrossing [mrad]
0 - 20
0 - 20
UTA, Sept 20, 2006
R&D
Detector Challenges of the ILC
Variation of the centre of mass energy,
due to very high current, collimated
beams: three main sources
Accelerator energy spread
Typically ~0.1%
Beamstrahlung
0.7% at 350 GeV
1.7% at 800 GeV
Initial state radiation (ISR)
Calculable to high precision in QED
Complicates measurement of
Beamstrahlung and accelerator
energy spread
Impossible to completely factorize
ISR from FSR in Bhabha scattering
But, there are many more challenges
Need: Reconstruct complete final state
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UTA, Sept 20, 2006
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SiD Design Concept
As example & because familiar with it
Calorimetry is the starting point in
the SiD design
Premises at the basis of concept:
muon system
muon system
solenoid
HCAL
HCAL
Particle flow calorimetry will deliver the
best possible performance
Si/W is the best approach for the ECAL
and digital calorimetry for HCAL
Limit calorimeter radius to constrain the
costs
Boost B-field to maintain BR2
Use Si tracking system for best momentum
resolution and lowest mass
Use pixel Vertex detector for best
pattern recognition
SiD
Detector is viewed as single fully integrated
system, not a collection of different
subdetectors
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Vertexing and Tracking
Tracking system is conceived as an integrated, optimized detector
Vertex detection
Inner central and forward pixel detector
Momentum measurement
Outer central and forward tracking
Integration with calorimeter
Integration with very far forward system
Detector requirements
Spacepoint resolution: < 4 mm
Impact parameter resolution
s r  s rz  5 10 /( psin 3 / 2  ) mm
Smallest possible inner radius
Momentum resolution 5 10-5 (GeV-1)
Transparency: ~0.1% X0 per layer
Stand-alone tracking capability
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UTA, Sept 20, 2006
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Vertex Detector
Five Barrels
Rin = 14 mm to Rout = 60 mm
24-fold phi segmentation
two sensors covering 6.25 cm
each
All barrel layers same length
Four Disks per end
Inner radius increases with z
Address electrical aspects:
Very thin, low mass sensors, including forward
region
 Integrate front-end electronics into the sensor
Reduce power dissipation so less mass is needed
to extract the heat
Mechanical aspects:
Integrated design
Low mass materials
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R (cm)
Small radius possible with large B-field
Goal is 0.1% X0/layer (100 mm of Si):
500 GeV, B=5 T
20 mrad xing
1
0
0
10
20
30
40 z (cm)
T. Maruyama
UTA, Sept 20, 2006
R&D
Vertex Detector Sensors: The Challenge
Beam structure
307 ns
0.2 s
2820x
0.87 ms
What readout speed is needed ?
Inner layer 1.6 MPixel sensors; Background hits significantly in excess of
1/mm2 will give patterns recognition problems
For SiD: cumulative
number of bunches
Once per bunch = 300ns per frame : too fast
to reach hit density
Once per train ~100 hits/mm2 : too slow
of 1/mm2
2
5 hits/mm => 50µs per frame: may be tolerable
Layer 1: ~35
Layer 2: ~250
Fast CCDs
Many different developments
Development well underway
Need to be fast (50 MHz)
Read out in the gaps
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MAPS
FAPS
HAPS
SOI
3D
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UTA, Sept 20, 2006
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Silicon Outer Tracker
5-Layer silicon strip outer tracker, covering Rin = 20 cm to Rout = 125 cm,
to accurately measure the momentum of charged particles
Support
Layer 5
Double-walled CF cylinders
Allows full azimuthal and
longitudinal coverage
Barrels
Five barrels, measure Phi only
Eighty-fold phi segmentation
10 cm z segmentation
Barrel lengths increase with
radius
Layer 1
Disks
Five double-disks per end
Measure R and Phi
varying R segmentation
Disk radii increase with Z
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UTA, Sept 20, 2006
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Calorimetry
Goal is jet energy resolution of 30%/√E
Current paradigm is that this can be achieved with Particle Energy Flow
A particle flow algorithm is a recipe to improve the jet energy resolution
by minimizing the contribution from the hadronic energy resolution by
reducing the function of a hadron calorimeter to the measurement of
neutrons and K0’s only
Measure charged particles in
the tracking system
Measure photons in the ECAL
Measure neutral hadrons in
the HCAL (+ ECAL) by
subtracting calorimeter energy
associated with charged
hadrons
H.Weerts
Particles in jets
Fraction of
energy
Measured with
Resolution [σ2]
Charged
~ 65 %
Tracker
Negligible
Photons
~ 25 %
ECAL with 15%/√E
0.072 Ejet
Neutral Hadrons
~ 10 %
ECAL + HCAL with 50%/√E
0.162 Ejet
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~20%/√E
UTA, Sept 20, 2006
R&D
EM Calorimeter
P-Flow requires high transverse and
longitudinal segmentation and dense
medium
Choice: Si-W can provide 5 x 5 mm2
segmentation and minimal effective
Molière radius
Absorber
X0 [cm]
RM [mm]
Iron
1.76
18.4
Copper
1.44
16.5
Tungsten
0.35
9.5
Lead
0.58
16.5
Maintain Molière radius by minimizing the gap between the W plates
Requires aggressive integration of electronics with mechanical design
SLAC/Oregon/BNL Design
LAPP, Annecy, Mechanical Design
30 layers, 2.5 mm thick W
~ 1mm Si detector gaps
Preserve RM(W)eff= 12 mm
Pixel size 5 x 5 mm2
Energy resolution 15%/√E + 1%
CAD overview
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UTA, Sept 20, 2006
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EM Calorimeter Layout
Tile W with hexagonal 6” wafers
~ 1300 m2 of Si
5x5 mm2 pads
Readout by single chip
1024 channels, bump-bonded
Signals
Single MIP with S/N > 7
Dynamic range of 2500 MIPs
< 2000 e- noise
Readout with kPix chip
Power
4-deep buffer (low occupancy)
Bunch crossing time stamp for
each hit
< 40 mW/wafer through
power pulsing !
Passive edge cooling
Testing
Prototype chip in hand with 2x32
channels
Prototype sensors in hand
Test beam foreseen in 2006
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UTA, Sept 20, 2006