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The Energy Frontier and a Lepton Collider
Barry BarishCaltech
Neutrino Oscillations in Venice13-April-08
11-Feb-08 Harvard Colloquium
The International Linear Collider 2
Answering the Questions
Three Complementary Probes + …
• Neutrinos as a Probe– Particle physics and astrophysics using a weakly
interacting probe
• High Energy Proton Proton Colliders– Opening up a new energy frontier ( ~ 1 TeV scale)
• High Energy Electron Positron Colliders– Precision Physics at the new energy frontier
• Increasing connections to Astrophysics/Cosmology
11-Feb-08 Harvard Colloquium
The International Linear Collider 3
Exploring the Terascalethe tools
• The LHC– It will lead the way and has large reach– Quark-quark, quark-gluon and gluon-gluon collisions at
0.5 - 5 TeV– Broadband initial state
• The ILC– A second view with high precision– Electron-positron collisions with fixed energies,
adjustable between 0.1 and 1.0 TeV– Well defined initial state
• Together, these are our tools for the terascale
11-Feb-08 Harvard Colloquium
The International Linear Collider 4
Three Generations of e+e- CollidersThe Energy Frontier
FourthGeneration?
SPEAR
PETRA
LEP
EN
ER
GY
YEAR 2020
1 Te
V
ILC
1970
1 Ge
V
11-Feb-08 Harvard Colloquium
The International Linear Collider 5
Possible TeV Scale Lepton Colliders
ILC < 1 TeVTechnically possible
~ 2019
QUADQUAD
POWER EXTRACTIONSTRUCTURE
BPM
ACCELERATINGSTRUCTURES
CLIC < 3 TeVFeasibility?
ILC + 5-10 yrsMain beam – 1 A, 200 ns from 9 GeV to 1.5 TeV
Drive beam - 95 A, 300 nsfrom 2.4 GeV to 240 MeV
Muon Collider < 4 TeV
FEASIBILITY??ILC + 15 yrs?
Much R&D Needed• Neutrino Factory R&D +• bunch merging• much more cooling• etc
ILC
CLIC
Muon Collider
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The International Linear Collider 6
Why e+e- Collisions ?
• Elementary particles
• Well-defined
– energy,
– angular momentum
• Uses full COM energy
• Produces particles democratically
• Can mostly fully reconstruct events
11-Feb-08 Harvard Colloquium
The International Linear Collider 7
LHC: Low mass Higgs: H MH < 150 GeV/c2
Rare decay channel: BR ~ 10-3
Requires excellent electromagnetic calorimeter performance
acceptance, energy and angle resolution,
g/jet and g/p0 separation Motivation for LAr/PbWO4
calorimeters for CMS
Resolution at 100 GeV: 1 GeV
Background large: S/B 1:20, but can estimate from non signal areas
CMS
11-Feb-08 Harvard Colloquium
The International Linear Collider 8
ILC: Precision Higgs physics
Model-independent Studies
• mass
• absolute branching ratios
• total width
• spin
• top Yukawa coupling
• self coupling
Precision MeasurementsGarcia-Abia et al
11-Feb-08 Harvard Colloquium
The International Linear Collider 9
The linear collider will measure the spin of any Higgs it can produce by measuring the energy dependence from threshold
How do you know you have discovered the Higgs ?
Measure the quantum numbers. The Higgs must have spin zero !
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The International Linear Collider 10
What can we learn from the Higgs?
Precision measurements of Higgs coupling
Higgs Coupling strength is proportional to Mass
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The International Linear Collider 11
e+e- : Studying the Higgsdetermine the
underlying model
SM 2HDM/MSSM
Yamashita et al Zivkovic et al
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The International Linear Collider 12
Top Quark Measurements
Bounds on axial ttbarZ and left handed tbW for LHC and ILC compared to deviations in various models
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The International Linear Collider 13
- Measure quantum numbers
- Is it MSSM, NMSSM, …?
- How is it broken?
ILC can answer these questions!
- tunable energy
- polarized beams
Supersymmetry at ILC
e+e- production crosssections
11-Feb-08 Harvard Colloquium
The International Linear Collider 14
New space-time dimensions can be mapped by studying the emission of gravitons into the extra dimensions, together with a photon or jets emitted into the normal dimensions.
Linear collider
Direct production from extra dimensions
?
11-Feb-08 Harvard Colloquium
The International Linear Collider 15
– E ~ (E4 /m4 R)– Cost ~ a R + b E
~ a R + b (E4 /m4 R)– Optimization : R ~ E2 Cost ~ c E2
• Circular Machine
Why Linear?cost
Energy
CircularCollider Linear
Collider
– Cost (linear) ~ a L – where L ~ E
R
m,E
SynchrotronRadiation
R
~ 200 GeV
11-Feb-08 Harvard Colloquium
The International Linear Collider 16
Parameters for the ILC
• Ecm adjustable from 200 – 500 GeV
• Luminosity ∫Ldt = 500 fb-1 in 4 years
• Ability to scan between 200 and 500 GeV
• Energy stability and precision below 0.1%
• Electron polarization of at least 80%
• The machine must be upgradeable to 1 TeV
11-Feb-08 Harvard Colloquium
The International Linear Collider 17
ILC – Underlying Technology
• Room temperature copper structures
OR
• Superconducting RF cavities
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The International Linear Collider 18
Superconducting RF Technology
• Forward looking technology for the next generation of particle accelerators: particle physics; nuclear physics; materials; medicine
• The ILC R&D is leading the way Superconducting RF technology– high gradients; low noise; precision optics
11-Feb-08 Harvard Colloquium
The International Linear Collider 19
main linacbunchcompressor
dampingring
source
pre-accelerator
collimation
final focus
IP
extraction& dump
KeV
few GeV
few GeVfew GeV
250-500 GeV
Designing a Linear Collider
Superconducting RF Main Linac
11-Feb-08 Harvard Colloquium
The International Linear Collider 20
Luminosity & Beam Size
• frep * nb tends to be low in a linear collider
• Achieve luminosity with spot size and bunch charge
Dyx
repb HfNn
L
2
2
L frep [Hz] nb N [1010] x [mm] y [mm]
ILC 2x1034 5 3000 2 0.5 0.005
SLC 2x1030 120 1 4 1.5 0.5
LEP2 5x1031 10,000 8 30 240 4
PEP-II 1x1034 140,000 1700 6 155 4
11-Feb-08 Harvard Colloquium
The International Linear Collider 21
• Low emittance machine optics• Contain emittance growth• Squeeze the beam as small as possible
Achieving High Luminosity
~ 5 nmInteraction Point (IP)
e- e+
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– 11km SC linacs operating at 31.5 MV/m for 500 GeV– Centralized injector
• Circular damping rings for electrons and positrons
• Undulator-based positron source
– Single IR with 14 mrad crossing angle– Dual tunnel configuration for safety and availability
ILC Reference Design
Reference Design – Feb 2007
Documented in Reference Design Report
11-Feb-08 Harvard Colloquium
The International Linear Collider 23
RDR Design Parameters
Max. Center-of-mass energy 500 GeV
Peak Luminosity ~2x1034 1/cm2s
Beam Current 9.0 mA
Repetition rate 5 Hz
Average accelerating gradient 31.5 MV/m
Beam pulse length 0.95 ms
Total Site Length 31 km
Total AC Power Consumption ~230 MW
11-Feb-08 Harvard Colloquium
The International Linear Collider 24
RDR Complete
• Reference Design Report (4 volumes)
ExecutiveSummary
Physicsat theILC
AcceleratorDetectors
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US/UK Funding and Future Prospects
• UK ILC R&D Program– About 40 FTEs. Leadership roles in Damping Rings and
Positron Source, as well as in the Beam Delivery System and Beam Dumps.
– All of this program is generic accelerator R&D, some of which will be continued outside the specific ILC project.
• US Program– ILC R&D was basically terminated for FY08, but a reduced
level ($42M FY07 ~$35M) program proposed for FY09.
– Presently a broad based U.S. program. Future??
– Generic SCRF also terminated in FY08, but expected to be restored in FY09: broad applications (e.g. Project X at Fermilab; fulure particle accelerators). Primary focus is to build US SCRF capability ($25M proposed for FY09)
11-Feb-08 Harvard Colloquium
The International Linear Collider 26
The Context
• THE SCIENCE !!!– Nothing has changed. A linear collider remains the consensus
choice as the highest priority long term investment for particle physics
• The Technology– Key technical, design & cost issues must be resolved before a
serious project could be proposed
• Increased Coordination with CERN CLIC R&D Program– A program to work together on areas of mutual interest was
initiated last fall, before the funding problems. – Major areas of cooperative work identified in February
• Conventional Facilities -- Civil, Cooling, Industry, etc• Non main linac technology – Particle sources, beam delivery• Detectors and simulations
11-Feb-08 Harvard Colloquium
The International Linear Collider 27
Technical Design Phase 1 -- 2010
• Technical risk reduction:– Gradient
• Results based on re-processed cavities• Reduced number 540 390 (reduced US program)
– Electron Cloud (CesrTA)
• Cost risks (reductions) – Main Cost Drivers– Conventional Facilities (water, etc)– Main Linac Technology
• Technical progress (global design)– Cryomodule baseline design is a being developed (e.g.
plug compatible parts)
11-Feb-08 Harvard Colloquium
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Technical Design Phase 2 - 2012
• RF unit test – 3 CM + beam (KEK)
• Complete the technical design and R&D needed for project proposal (exceptions*)– Documented design– Complete and reliable cost roll up
• Project plan developed by consensus– Cryomodule Global Manufacturing Scenario– Siting Plan or Process
ILC – Global Design Phase
2005 2006 2007 2008 2009 2010 2012 ?????
Global Design Effort
Baseline configuration
Reference Design
R&D Program
Technical Design
Siting Studies
International Mgmt
LHCPhysics
Omnibus
Omnibus
Project
11-Feb-08 Harvard Colloquium
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ILC Reference Design and Plan
Producing Cavities
Cavity Shape
Obtaining Gradient
11-Feb-08 Harvard Colloquium
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Cavity Gradient – Results
KEK single cell results:2005 – just learning2006 – standard recipe2007 – add final 3 μm fresh acid EPNote: multi-cells are harder than singles
2005
2007
2006
11-Feb-08 Harvard Colloquium
The International Linear Collider 32
Superconducting RF Cryomodule
11-Feb-08 Harvard Colloquium
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ILC Reference Design and Plan
Making Positrons6km Damping Ring
10MW Klystrons
Beam Delivery and Interaction Point
11-Feb-08 Harvard Colloquium
The International Linear Collider 34
Electron cloud – Goal
• Ensure the e- cloud won’t blow up the e+ beam emittance.– Do simulations (cheap)– Test vacuum pipe coatings, grooved
chambers, and clearing electrodes effect on e- cloud buildup
– Do above in ILC style wigglers with low emittance beam to minimize the extrapolation to the ILC.
11-Feb-08 Harvard Colloquium
The International Linear Collider 35
E Cloud – Results
SLAC
11-Feb-08 Harvard Colloquium
The International Linear Collider 36
~30 km long tunnel
Particle Detector
Main Research Center
Two tunnels • accelerator units• other for services - RF power
Linear Collider Facility
11-Feb-08 Harvard Colloquium
The International Linear Collider 37
Conventional Facilities
72.5 km tunnels ~ 100-150 meters underground
13 major shafts > 9 meter diameter
443 K cu. m. underground excavation: caverns, alcoves, halls
92 surface “buildings”, 52.7 K sq. meters = 567 K sq-ft
11-Feb-08 Harvard Colloquium
The International Linear Collider 38
Detector Concepts Report
11-Feb-08 Harvard Colloquium
The International Linear Collider 39
Detector Performance Goals
11-Feb-08 Harvard Colloquium
The International Linear Collider 40
Detector Performance Goals
11-Feb-08 Harvard Colloquium
The International Linear Collider 41
Detector Performance Goals
• ILC detector performance requirements and comparison to the LHC detectors:○ Inner vertex layer ~ 3-6 times closer to IP
○ Vertex pixel size ~ 30 times smaller
○ Vertex detector layer ~ 30 times thinner
Impact param resolution Δd = 5 [μm] + 10 [μm] / (p[GeV] sin 3/2θ)
○ Material in the tracker ~ 30 times less
○ Track momentum resolution ~ 10 times better
Momentum resolution Δp / p2 = 5 x 10-5 [GeV-1] central region
Δp / p2 = 3 x 10-5 [GeV-1] forward region
○ Granularity of EM calorimeter ~ 200 times better
Jet energy resolution ΔEjet / Ejet = 0.3 /√Ejet
Forward Hermeticity down to θ = 5-10 [mrad]
11-Feb-08 Harvard Colloquium
The International Linear Collider 42
detectorB
may be accessible during run
accessible during run Platform for electronic and
services (~10*8*8m). Shielded (~0.5m of concrete) from five sides. Moves with detector. Also provide vibration isolation.
Concept of IR hall with two detectors
The concept is evolving and details being worked out
detectorA
11-Feb-08 Harvard Colloquium
The International Linear Collider 43
Conclusions
• The energy frontier continues to be a primary tool to explore the central issues in particle physics
• The LHC at CERN will soon open the 1 TeV energy scale and we anticipate exciting new discoveries
• A companion lepton collider appears to be the logical next step, but such a machine has technical challenges and needs significant R&D and design now
• LHC results will inform the final design and even whether a higher energy options is needed, If so, this may also be possible, but on a longer time scale.