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Presentation at NEPPSRAugust 21st, 2003

byProfessor Homer Neal (Yale)

What is a linear collider and what can it doThe role of a LC in the LHC eraThe NLC/JLC/TESLA linear collider R&D & Detector(s)Steps to fruition

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Why leptons? The proton is not a simple object

This is a bit of an exageration because it is Au on Au but its not far from the truth

Why electrons and not muons or tau leptons?Muon decay creates currently insurmountable difficultieslike neutrino radiation. Taus are even worse.

Why linear?Small mass particles lose a lot of energy whenaccelerated in a circle at high energies.

Energy loss per turn:

���radiuseE

422

34 ���

Loss 1013 worse for e than p

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Large Hadron Collider:Good luminosity and“easy” to get to high energiesbut with low energy precisionand no beam polarization

Challenges: high event rate andradiation level

Lepton collider: Colliding bare partons � collisionenergy precisely known, polarizatiocontrolable, collision point welldetermined, energy tunable

Lower event rates and backgroundsbut still a challenge for precise/delicate inner detectors

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An Example of Beautiful Clean Physics at a Lepton Linear Collider

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~100 m

Positron Main Linac240-490 GeV (X)

Electron Main Linac240-490 GeV (X)

9.9 km

9.9 km

~5 km

e+ Target

2 GeV (L)Pre-DampingRing (UHF)

DampingRing

(UHF)

DampingRing

(UHF)

2 GeV (S)

136 MeV (L)

6 GeV (S)

560 m

170 m

560 m

ElectronInjector

200 m

510 m

10 m

~10 m

~100 m 0.6 GeV (X)

0.6 GeV (X)

Pre-Linac 6 GeV (S)

Pre-Linac6 GeV (S)

136 MeV (L)

RF Systems 11.424 GHz 2.856 GHz1.428 GHz0.714 GHz

8047A61110-2000

e–

e–

Hi EDetector

Low E Detector

FinalFocus

FinalFocus

~20 m

~20 m

Dump

Dump

~300 m

Compressor

Compressor

Compressor

Compressor

e+

e+

e–

(X)(S)(L)(UHF)

PositronInjector

Fromthis �

To this �

Note: Full NLClength not shown!!!

~25 km long!

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Justifications for the push tohave higher energy colliders

We still haven't found the Higgs and it is essential for understanding

how the particle masses are generated

There are many indications of the existence of new physics accessible

at the next generation of colliders:

Dark matter - what is the source of all that matter (SUSY CDM may be the answer)

Dark energy - why cannot we fully explain "the“ accelerating universe

Matter dominance - If BaBar/Belle measurements continue to match the SM predictions, we've got a problem. (can we detect CP violation in the lepton sector)� cosmological time dependence (maybe some clues

from precision high energy measurements)

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Why all the Hoopla Concerning Models like SUSYSolves naturallness problem:Divergent terms are automaticallycancelled by terms from thesuperpartners:

potentially unifies SM forcesincluding gravity

includes a Higgs mechanismwith a heavy top

predicted

provides a dark matter candidate

could potentially have strong enough CP violation to explain observedmatter dominance

222

222

2

222

44~ S

SF

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23.0sin2�W�

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Point 1 2 3 4 5 6GeV GeV GeV GeV GeV GeV

�����

�� 336 336 90 160 244 92

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�� 494 489 142 228 355 233

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�� 650 642 192 294 464 304

�����

�� 1089 858 368 462 750 459

e e/ ��� 920 922 422 1620 396 470

���� 860 850 412 1594 314 264

Z h 186 207 160 203 184 203

Z H/A 1137 828 466 950 727 248

H+ H - 2092 1482 756 1724 1276 364

q q 1882 1896 630 1828 1352 1010

reaction

Sparticle Spectrums for various SUSY Model Parameter Se

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Answers/Resolutions to these issueswill results from discovery of

new physics along with precisionmeasurements that will elucidatewhat model is the correct model

of nature.

Even if you don't believe in SUSY or even in the Higgs, it is essentially impossible to construct a model where

there is not some new physics that will be discovered by the future colliders.

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Conclusions from:"The Case for a 500 GeV e+e- Linear Collider"

All known models with a fundamental Higgs boson satisfy mh < 205 GeV

Any model using the current EW data that has mh>500 GeV predicts other observable new physics phenomena at < 500 GeV

The lightest SUSY particles are most probable to appear at < 500 GeV and all charginos/neutralinos at < 800 GeV

The observation of no new physics at LHC would increase the necessity of precision EW measurements at the LC

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The Justification for a LHC and a LC

As in the past, the physics progress greatly benefits from having hadron and lepton machines operating simultaneously.

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While the main role of discovery will go to the LHC,the future linear collider will be essential in clarifying

what those discoveries are and for measuring the properties of any new particles

(mass, spin, couplings).

The LC and LHC play a symbiotic role. The discoveries at the LHCwill be analyzed by the LC and in term provide feedback essential

for further LHC exploration.

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Furthermore, there are many measurements/observationsthat will only be possible at either

the LHC or the LC

Its quite possible that LHC will see a wealth of signals and will need the lc to determine what some of those are and in turn influence what the lhc running

program should be,

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There are many competing physics processes andthe polarization help to separate and verify processe

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From the analysis of SUSY (SPS) point 1a at ATLAS and CMSReconstructed masses of squarks and gluinos are correlated tothe mass of the neutralino through the analysisof the sparticles in the decay chain

Using the measurement of fromthe LC greatly improves the LHC massmeasurement for other sparticles

1o

m�

Gjelsten, Lykten, Miller, Osland, Polesello

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We thank the Higgs is almost in the bag ...

CMS/ATLAS should easily see it, but they'llneed the LC to verify that it is indeed the Higgs and to make precision measurements of its properties.

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The Higgs at a LC

Measurement of the Higgsbranching ratios allows oneto verify that it is indeed theHiggs that you've found!

e+e-�Zh produces 40,000 Higgs/year

Clean initial state gives precision Higgs mass measurement

Model independent Higgs branching ratios

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Precission Higgs Mass Measurements

Expected Higgs signal at a500 GeV LC for 30 /fb

very clean .... very precise

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In many parts of theparameter space, only a single Higgs decay mode can be observed by LHC

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Extrapolation of the susy mass parameters measured at a LC from theTeV scale to the grand unification scale.

gaugino massparameters

gluinos andsquarks massparameters

Note: Very difficult to do at LHC

from selectronmeasurements

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Precision Measurements

A LC could run at the Z polewith high luminosity yielding~Giga Z's per year.

Also, there exist the possibilityof having a dedicated low energy interaction region detector for either physics at the Z, W-pair or top pair threshold.

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Some More Fun Physicsextra-dimensions: many theories forexplaining the weakness of gravityand even the time evolution of a involvemodels with an extra-dimension.A LC could observe the pressence of thisextra dimension.

Physics Today, February, 2002

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Polarizing the beams

Much more difficult for positrons!!!!

P. Saez et al.

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At issue:

An e+e- linear collider

operating at about a TeV with possible upgrade to several TeV�1034 cm2/sec �300 fb-1/yr)with one or two detectors

polarized electron beam (Pe = 80%)possibly a polarized positron beam

possibly a gamma-gamma collision optioneither warm or cold acceleration technology

A long-term facility with regional control and analysis centersaround the globe.

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US/North America

Japan(The Asian Committee for Future Accelerators )

Europe(the European Committee for Future Accelerators )

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Baseline design:

25 km site

two 10 km linacs sized for 1 TeV

fill ½ of linacs for 500 GeV

Final focus, Injector design for 1.5 TeV.

Possibly two IRs; one for TeVcollisions

the other operating upto 500 GeV

Electron Polarization�80%

~100 m

Positron Main Linac240-490 GeV (X)

Electron Main Linac240-490 GeV (X)

9.9 km

9.9 km

~5 km

e+ Target

2 GeV (L)Pre-DampingRing (UHF)

DampingRing

(UHF)

DampingRing

(UHF)

2 GeV (S)

136 MeV (L)

6 GeV (S)

560 m

170 m

560 m

ElectronInjector

200 m

510 m

10 m

~10 m

~100 m 0.6 GeV (X)

0.6 GeV (X)

Pre-Linac 6 GeV (S)

Pre-Linac6 GeV (S)

136 MeV (L)

RF Systems 11.424 GHz 2.856 GHz1.428 GHz0.714 GHz

8047A61110-2000

e–

e–

Hi EDetector

Low E Detector

FinalFocus

FinalFocus

~20 m

~20 m

Dump

Dump

~300 m

Compressor

Compressor

Compressor

Compressor

e+

e+

e–

(X)(S)(L)(UHF)

PositronInjector

Possibilities:•Positron polarization•e- e- collision• �� collisions

The Next Linear Collider (NLC) – North American Styl

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Next Linear Collider Test Accelerator(NLCTA @ SLAC)Small accelerator prototype

The Final Focus Test Beam facility(FFTB @ SLAC) developing and validating the opticaldesign of linear collider final beam focussystems for obtaining stable and extremely narrow beams.

Accelerator Test Facility (ATF @ Kou Enerugii Kosokuki Kenkyuu Kikou)A test damping ring for the low emittance beams required for the NLC

The Accelerator Structure SETup (ASSET)

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ID: 104 project_size: skill_type: short project description: Processing of superconducting half-cells before welding (chemistry, Ti vacuum bake)ID: 116 project_size: skill_type: short project description: Low Level RF System SimulationsID: 95 project_size: small skill_type: physicistshort project description: Remote operation of TESLA Test Facility linac at DESYID: 96 project_size: small skill_type: physicistshort project description: Remote operation of Photoinjector Laboratory (FNPL) at FermilabID: 97 project_size: skill_type: physicistshort project description: Consider needs of LC remote operation systemID: 98 project_size: large skill_type: short project description: Accelerator Control and Machine Protection System (MPS)ID: 99 project_size: small skill_type: materials scienceshort project description: Mechanical properties and microstructure, metallic and interstitial gases, material specification.ID: 100 project_size: skill_type: materials scienceshort project description: RRR issues - hydrogen degassing, Ti firing, low temperature bakeout.ID: 101 project_size: medium skill_type: physicistshort project description: Improved scanning of superconducting materials - eddy current, squidsID: 103 project_size: large skill_type: materials scienceshort project description: : Explore the use of materials other than Nb in superconducting cavities, e.g., Nb3Sn.ID: 105 project_size: small skill_type: short project description: TESLA Cavity Flanges and Seals.ID: 111 project_size: skill_type: short project description: low level RF Digital Feedback Hardware

A Sample of LC Accelerator Projects (from the Himmel L

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:75MW:1.6 �s:120 Hz

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Solution found forproblem with deterioration at input toacceleration structure!!!

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- from Torr Robenheimer

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from: JLC Roadmap Report Draft releasedFebruary 12, 2003

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TESLA Specifications

total length of the facility 33 km(including two 15-kilometer acceleration sections)

accelerator tunnel with approx. 5 m diameter

collision energy of 500 GeVX-ray wavelength of 5 to 0.05 nanometer

~20k superconducting accelerating structures

operating temperature of 2 K, i.e. -271 deg Celsius

depth underground 10 - 30 meterscollision points/particle physics

experiments Initially one(expandable to two, in an underground

hall)number of cryogenic halls 7

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The Tesla layout taken from thecompleted TESLA TDR.

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The TESLA high gradient superconducting accelerating cavities

For a 500 GeV center of mass linear collider needs accelerating fieldsof about 25 MV/m.

800 GeV requires about 35 MV/m.

cavity frequency 1.3 GHz; standing wave pi-mode operationoperation temperature 2 K (-271 deg Celsius)cavity bandwidth approx. 400 Hzmaterial: Niobium with high thermal conductivity fabrication technique:

* electron beam welding* hydro forming* spinning

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* studies at the TESLA Test Facility 1999 / 2000

* demonstration of the new SASE FEL principle 1999 / 2000

* complete project proposal, approval 2001

* project ready for final decision 2001 / 2002

* estimated construction time 6 to 8 years

A Proposed Schedule for TESLA

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Tunnel Route

* In order to fully exploit the research potential of the new facility, the TESLA tunnel must bconstructed as an exact extension of the western straight section of the HERA accelerator

* In other words, the TESLA tunnel will begin on the DESY site in Hamburg and run in a north-northwesterly direction through the district ofPinneberg in Schleswig-Holstein

* The electron-positron collision zone lies on the outskirts of Ellerhoop, some 16.5 kilometers from DESY. When complete, the site will accommodate the underground hall for particle physics experiments and an X-ray laser facility. It will also house various supply and infrastructural facilities

* In addition, seven large supply halls, all with access to the tunnel, will be strategically located along the route.

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Free Electron Laser for X-raysExtremely high beam currents would be produced at very low beam emittance, i.e. very high beam quality. The basis of the FEL principle for wavelengths within the nanometer region and below it can be summarized as follows: short electron bunches are made to emit coherent synchrotron radiation while passing through a long undulator - a long magnetic structure with rapidly alternating field directions. The goal of the TTF FEL is a unique source of coherent radiation in the VUV range, i.e. with wavelengths of approx. 6 nanometers.

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US involvement in TESLA

* APS/Argonne, Chicago, IL

* Cornell University, Ithaca, NY

* Fermilab, Batavia, IL

* Thomas Jefferson National Laboratory, Newport News, VA

* UCLA Dep.of Physics, Los Angeles, LA

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A 1 TeV machine doesn't mean that that's its limit.

Remember: LEPII got to higher and higher energies during a given run with mini-ramps using a similar concept.

Energy and luminosity can be played against each other.

D. Burke

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Photon-Photon Option would allow:

direct production of positive charge parity resonances such the SM Higgs boson

production of heavy Higgs bosons with masses < 1.5 ECMpair production of charged Higgs bosons with 10x the cross-section for

electron-positron collisions

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Upgrade Paths

Pulse structure most suitable for adding onto a warm LC.

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The LC Detector(s)

TESLA detectors

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Detector Challenges in Comparison to those for ATLAS/CMShttp://blueox.uoregon.edu/~lc/randd.html

3-6 times closer inner vertex layer to the IP (higher vertexing precision),

30 times smaller vertex detector pixel sizes (improved position resolution andtwo-track resolution),

30 times thinner vertex detector layers (reduced multiple scattering and photon conversions),

6 times less material in the tracker (better momentum resolution and reduced photon conversions),

10 times better track momentum resolution (better event selection purity) and

200 times higher granularity of the electromagnetic calorimeter, enabling sophisticated energy flow algorithms.

However, the radiation hardness requirements are significantly less than at the LHC.

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The NLC Large Detector Current Model

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Large Detector Tracking Systems

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The Vertexing as an Example of Required R&D

The detector has to bemade tolerant to thee+e- pairs produced atwhatever radius ischosen.

levels at JLC/NLC/TESLA expected to be 100 to 1000x higher than at SLC

the neutron backgrounds are expected to be ~3 x 108

neutrons/cm2/sec

(also 100 to 1000x higher than at SLC)

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Background in VXD at 1.5 cm with B=3 Tesla4x10-6 hits/pixel/bunch(NLC/JLC), 12x10-6 hits/pixel/bunch(TESLA)

�Requirement for NLC/JLC ~8 msec readout time�Requirement for TESLA ~50 �sec

(due to large number of bunches in a pulse train)

�Expect to achieve a readout rate of 25µ50 MHz�Remaining factor of improvement can be obtained from increasing the number of readout channel

VXD: 4 JLC JLC/NLC: ~36 for 25 MHzTESLA: ~3000 readout amplifiers at 50 Mhz

The background and bunch structure

stress the vertex detector readout

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The detectors have to bethinned to reduce multiple-scattering and sensitivity tobackgrounds.

Have to find a way to supportthinned structures without break them!

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Estimated Detector Costs

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International Organizing Committee of the Worldwide Study of Physics and Detectors for Future Linear e+e- Colliders

Co-chairs

* Charles Baltay, Yale University* Sachio Komamiya, University of Tokyo* David Miller, U. C. London

North American Committee Members

* Jim Brau, University of Oregon (USA)* Robert Carnegie, (Canada)* Paul Grannis, SUNY, Stony Brook (USA)* Mark Oreglia, University of Chicago (USA)* Charles Prescott, SLAC (USA)

Asian Committee Members

* Shinhong Kim, Tsukuba University (Japan)* Joo Sang Kang, Korea University Seoul (Korea)* Takayuki Matsui, KEK (Japan)* G. P. Yeh, Taiwan* Tao Huang, University of Beijing (China)

European Committee Members

* Michael Danilov, ITEP (Russia)* Rolf Heuer, CERN/DESY (Germany)* Marcello Piccolo, Frascati (Italy)* Francois Richard, Orsay (France)* Ron Settles, Munich (Germany)

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The American Linear Collider Physics Group

Leaders: " Jim Brau (U. Oregon, jimbrau@faraday.uoregon.edu)" Mark Oreglia (U. Chicago, oreglia@hep.uchicago.edu)

Executive committee:1 Ed Blucher (University of Chicago, blucher@hep.uchicago.edu)1 Dave Gerdes (University of Michigan, gerdes@umich.edu)1 Lawrence Gibbons (Cornell, lkg@mail.lns.cornell.edu)1 Dean Karlen (University of Victoria, karlen@uvic.ca)1 Young-Kee Kim (University of California, Berkeley, ykkim@lbl.gov)1 Hitoshi Murayama (University of California, Berkeley, murayama@hitoshi.berkeley.edu)1 Jeff Richman (University of California, Santa Barbara, richman@hep.ucsb.edu)1 Rick Van Kooten (Indiana University, rickv@paoli.physics.indiana.edu)

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Groups within the ALCPG

Detector and Physics SimulationsVertex DetectorTrackingParticle I.D.CalorimetryMuon DetectorData Acquisition, Magnet, and InfrastructureInteraction Regions, Backgrounds: Stan HertzbachIP Beam InstrumentationHiggsSUSY New Physics at the TeV Scale and BeyondRadiative Corrections (Loopverein)Top Physics, QCD, and Two Photon Precision Electroweakgamma-gamma, e-gamma Optionse-e-LHC/LC Study Group

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Getting support from DOEfor University LC R&D

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Globalisation

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DESY PRESS INFORMATION, Hamburg, November 18, 2002

German Science Council Recommends International Accelerator Project TESLA

The German Science Council, an agency of the German government, assessed the TESLA project planned by the research center DESY in cooperation with international partners to, be worthy of support under certain conditions. The assessments of nine appraised large scale facilities for basic research in thenatural sciences have been published today. "We are very glad that the Science Council changed its first positive statement about TESLA to the German federal government to a recommendation, and we are looking forward to hear the upcoming evaluations" said Professor Albrecht Wagner, chairman of the DESY Directorate, "since we have complied with the conditions posed by the Science Council".

The Science Council listed two conditions in its first evaluation statement: to detail the project proposal for the superconducting electron-positron linear collider with respect to international funding and cooperation, and to present a revised technical project proposal for the TESLA X-ray laser version with a separate linear accelerator. In October, DESY sent the corresponding papers to the Science Council: a draft for the administrative, organizational and financial structures of an international linear collider collaboration and a complementary technical project proposal for the X-ray laser as well as a respective memorandum for each theme, including the current scientific-political developments. These papers will influence the further evaluation. The final decision of the federal government regarding the TESLA project is expected in 2003.

TESLA stands for TeV-Energy Superconducting Linear Accelerator - a particle accelerator facility operating at teraelectronvolt energy which is being developed in an international collaboration. TESLA comprises of a 33-kilometer-long linear accelerator bringing electrons into collision with their antiparticles, the positrons, and an X-ray laser laboratory. The special feature of the new facility: A new type of superconducting accelerators allow collisions between particles at an extremely high level of energy and serve as a source of intense and extremely short X-ray flashes with laser properties. The TESLA X-ray lasers will offer new perspectives for research in different disciplines - from physics and chemistry to biology, materials research and medicine. TESLA is to be established

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Here is a translation of today's press release from the German Federal Ministry for Education and Research. See http://www.bmbf.de/presse01/798.html for the original.

Andreas KronfeldBULMAHN GIVES GREEN LIGHT TO LARGE-SCALE FACILITIES

thereby ensuring Germany's international top position in basic research

[Edelgard Bulmahn is the minister for research. There are four paragraphs in which she says how important basic research in science is for Germany. I don't have time to translate it all. It says that 1.6 Billion Euro are planned for largprojects, and that these large projects require close international cooperation. Scroll down to ``Entscheidung über die Großgeräte der naturwissenschaftlichen Grundlagenforschung'', and I'll start from there.]

Decision on Large-scale Facilities for Basic Research in the Natural Sciences........

- The reseach center DESY in Hamburg shall receive a new kind of free electron laser. Because of the location ofthe site, Germany is prepared to carry half of the 673 million Euro investment cost. Discussions on European cooperation will proceed expeditiously, so that in about two years a construction decision can be taken. Constructionwill take about six years. Today no German site for the TESLA linear collider will be put forward. This decision is connected to plans to operate this project within a world-wide collaboration. Therefore, one must waon developments abroad. On the question of site, it is neither sensible nor necessary for Germany to act alone. DESY will, however, be allowed to continue its research work [on TESLA] in the existing international framework, to facilitate German participation in a future global project.

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The decisions of the German Ministry for Education and Research concerningTESLA was published on 5 February 2003:

TESLA X-FELDESY in Hamburg will receive the X-FEL Germany is prepared to carry half of the 673 MEuro investment cost. Discussions on European cooperation will proceed expeditiously, so that iabout two years a construction decision can be taken.

TESLA ColliderToday no German site for the TESLA linear collider will be put forward.This decision is connected to plans to operate this project within a world-wide collaborationDESY will continue its research work on TESLA in the existing international framework, to facilitate German participation in a future global project

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'The path chosen by TESLA to move towards approval was recommended by the German Science Council and is generally considered to be the fastest one.

'Community will now take the other path used for international projects (e.g. ITER):

unite first behind one project with all its aspects, including the technology choice, and then

approach all possible governments in parallel in order to trigger the decision process and site selection.

'ICFA initiative for an international co-ordination:

Asian SG European SGUS SG

International LC SC

ECFAGov GovGov

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J. Hewett

2003

Tevatron

20202007 2010 2012 2015 2018

LHCLHCUpgrade

LISA SNAP/LSST

LC: Phase I

WMAPAuger

GLASTPLANCK

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Reconstructing the Higgs otential

V(�H) = mH2�H

2/2 +�v�H3 + ��H

4/4

Assume � = � = �SM = mH2 /2v 2

Higgs self-coupling determined with better accuracy at:

• LC for mH < 140 GeV• LHC for mH > 140 GeV

LHC measurements improve with LC input on Higgs properties

BaurBaur, , PlehnPlehn, Rainwater , Rainwater ~~

~~

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Specific US Issues

What is the future for physics in the US????

If the only possibility is to build the facility in europe or Japan, will the US government provide its share of the funding for a facility abroad?

Will the US physicists being content having the only major HEP facilitiesoutside the country?

What will become of Fermilab?

What will SLAC's role be even if the facility is built in the US?

How do you invision using the regional centers for students?

How to make the case to the government?

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Guidance on projectsfrom Rogers, Himel,

and Finley

Individual Investigators

Prioritized Recommendations

Funding profilefrom NSF

Funding profilefrom DOE

AcceleratorReview Committee

Individual Investigator's Desires

University LC Accelerator & Detector R&D Funding

Guidance on prioritiesfrom U.S. Physics & DetectorGroup (Oreglia & Brau) and

International Group(Hoyer et al)

Consortia Proposals

DetectorReview Committee

NSF DOE$ $

DOE ConsortiumNSF Consortium

July 14, 2003 American Linear Collider Workshop

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(from HEPAP report)

RECOMMENDATION 1: We recommend that the United States take steps to remain a world leader in the vital and exciting field of particle physics, through a broad program of research focused on the frontiers of matter, energy, space and time.

The U.S. has achieved its leadership position through the generous support of the American people. We renew and reaffirm our commitment to return full value for the considerable investment made by our fellow citizens. This commitment includes, but is not limited to, sharing our intellectual insights through education and outreach, providing highly trained scientific and technical manpower to help drive the economy, and developing new technologies that foster the health, wealth and security of our nation and of society at large.

RECOMMENDATION 3: We recommend that the highest priority of the U.S. program be a high-energy, high-luminosity, electron-positron linear collider, wherever it is built in the world.This facility is the next major step in the field and should be designed, built and operated as a fully international effort.

We also recommend that the United States take a leadership position in forming the international collaboration needed to develop a final design, build and operate this machine. The U.S. participation should be undertaken as a partnership between DOE and NSF, with the full involvement of the entire particle physics community. We urge the immediate creation of a steering group to coordinate all U.S. efforts toward a linear collider.

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Words of Motivation from Neil Calder:

In the last 10 years there has been a revolution in our concept of the Universe and the realities of our new knowledge are much stranger than could have been imagined. The ingredients of our universe were first accurately measured as recently as March this year. The results are staggering - 4% Atoms, 23% Dark Matter, 73% Dark Energy.

The implications of this new understanding are enormous. We, and everything we can see with our most powerful instruments, make up only 4% of the Universe. We are a tiny minority. The rest is waiting to be discovered. We are at a turning point in the history of knowledge. Has there ever been more compelling challenge for exploration?

The Linear Collider is the key to understanding this weird and wonderful universe that we inhabit. Making precise measurements is the name of the game and only accelerator based experiments can provide the controlled conditions needed to make sense of the new cosmological observations. Measure, measure, measure is the imperative for historic discoveries!

The Linear Collider will not only investigate new frontiers in physics and technology but also in international science collaboration. This project will go ahead as a closely coordinated international collaboration, with shared costs and shared benefits, on a scale and scope never before seen in science. The US is the world’s foremost scientific nation. Participation in the Linear Collider will reinforce this leadership and give our young scientists the challenge of taking part in the most exciting scientific quest of the 21st

century.

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Its an exciting time for high-energy physics and its exploration through a new generation of high-energy colliders

The case for a high energy e+e- LC is strong

There are many opportunities for research and development and a new push is being made to reenergize the effort in the US

While the path through the red-tape is not obvious and serious thought is needed, the main focus should be on the importance of the physics and the thorough design of the accelerator and detector.