News from the ILC

Barry BarishUsers’ Meeting

Fermilab 9-June-05

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Why e+e- Collisions?

• elementary particles

• well-defined

– energy,

– angular momentum

• uses full COM energy

• produces particles democratically

• can mostly fully reconstruct events

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A Rich History as a Powerful Probe

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The Energy Frontier

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Why a TeV Scale?

• Two parallel developments over the past few years (the science)

– The precision information e+e- and data at present energies have pointed to a low mass Higgs; Understanding electroweak symmetry breaking, whether supersymmetry or an alternative, will require precision measurements.

– There are strong arguments for needing both pp and e+e- collisions to fully exploit the exciting science expected in the 1 TeV energy scale.

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Why a TeV Scale e+e- Accelerator?

• Two parallel developments over the past few years (the technology)

– Designs and technology demonstrations have matured on two technical approaches for an e+e- collider that are well matched to our present understanding of the physics.

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Which Technology to Choose?

– Two alternate designs -- “warm” and “cold” had come to the stage where the show stoppers had been eliminated and the concepts were well understood.

– A major step toward a new international machine required uniting behind one technology, and then working toward a unified global design based on the recommended technology.

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International Technology Review Panel

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Evaluate a Criteria Matrix

• The panel analyzed the technology choice through studying a matrix having six general categories with specific items under each:– the scope and parameters specified by the ILCSC; – technical issues; – cost issues; – schedule issues; – physics operation issues; – and more general considerations that reflect the

impact of the LC on science, technology and society

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The Recommendation

• We recommend that the linear collider be based on superconducting rf technology

– This recommendation is made with the understanding that we are recommending a technology, not a design. We expect the final design to be developed by a team drawn from the combined warm and cold linear collider communities, taking full advantage of the experience and expertise of both (from the Executive Summary).

– The superconducting technology has several very nice features for application to a linear collider. They follow in part from the low rf frequency.

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The Community then Self-Organized

Nov 13-15, 2004

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The First ILC Meeting at KEK

The Global Design Effort

Formal organization begun at LCWS 05 at Stanfordin March 2005 when I became director of the GDE

Technically Driven Schedule

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GDE – Near Term Plan

• Staff the GDE– Administrative, Communications, Web staff– Regional Directors (each region)– Engineering/Costing Engineer (each region)– Civil Engineer (each region)– Key Experts for the GDE design staff from the world

community (please give input)– Fill in missing skills (later)

Total staff size about 20 FTE (2005-2006)

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GDE – Near Term Plan

• Schedule• Begin to define Configuration (Aug 05) • Baseline Configuration Document by end of 2005

-----------------------------------------------------------------------• Put Baseline under Configuration Control (Jan

06) • Develop Reference Design Report by end of 2006

• Three volumes -- 1) Reference Design Report; 2) Shorter glossy version for non-experts and policy makers ; 3) Detector Concept Report

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GDE – Near Term Plan

• Organize the ILC effort globally– First Step --- Appoint Regional Directors within the

GDE who will serve as single points of contact for each region to coordinate the program in that region. (Gerry Dugan (North America), Fumihiko Takasaki (Asia), offered to Brian Foster (Europe))

– Make Website, coordinate meetings, coordinate R&D programs, etc

• R&D Program– Coordinate worldwide R & D efforts, in order to

demonstrate and improve the performance, reduce the costs, attain the required reliability, etc. (Proposal Driven to GDE)

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main linacbunchcompressor

dampingring

source

pre-accelerator

collimation

final focus

IP

extraction& dump

KeV

few GeV

few GeVfew GeV

250-500 GeV

Starting Point for the GDE

Superconducting RF Main Linac

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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

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Towards the ILC Baseline Design

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rf bands:

L-band (TESLA) 1.3 GHz = 3.7 cm

S-band (SLAC linac) 2.856 GHz 1.7 cm

C-band (JLC-C) 5.7 GHz 0.95 cm

X-band (NLC/GLC) 11.4 GHz 0.42 cm

(CLIC) 25-30 GHz 0.2 cm

Accelerating structure size is dictated by wavelength of the rf accelerating wave. Wakefields related to structure size; thus so is the difficulty in controlling emittance growth and final luminosity.

Bunch spacing, train length related to rf frequency

Damping ring design depends on bunch length, hence frequency

Specific Machine Realizations

Frequency dictates many of the design issues for LC

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Cost Breakdown by Subsystem

cf31%

structures18%rf

12%

systems_eng8%

installation&test7%

magnets6%

vacuum4%

controls4%

cryo4%

operations4%

instrumentation2%

Civil

SCRF Linac

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TESLA Cavity

9-cell 1.3GHz Niobium Cavity

Reference design: has not been modified in 10 years

~1m

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What Gradient to Choose?

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Gradient

Results from KEK-DESY collaboration

must reduce spread (need more statistics)

single

-cell

measu

rem

ents

(in

nin

e-c

ell

cavit

ies)

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(Improve surface quality -- pioneering work done at KEK)

BCP EP

• Several single cell cavities at g > 40 MV/m

• 4 nine-cell cavities at ~35 MV/m, one at 40 MV/m

• Theoretical Limit 50 MV/m

Electro-polishing

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How Costs Scale with Gradient?

Relative

Co

st

Gradient MV/m

2

0

$ lincryo

a Gb

G Q

35MV/m is close to optimum

Japanese are still pushing for 40-45MV/m

30 MV/m would give safety margin

C. Adolphsen (SLAC)

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Fermilab - Emerging ILC SCRF Program

H Carter

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Fermilab ILC SCRF Program

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Fermilab ILC SCRF Program

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Fermilab ILC SCRF Program

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Fermilab ILC SCRF Program

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Fermilab ILC SCRF Program

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TESLA Cavity

9-cell 1.3GHz Niobium Cavity

Reference design: has not been modified in 10 years

~1m

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Evolve the Cavities Minor Enhancement

Low Loss Design

Modification to cavity shape reduces peak B field. (A small Hp/Eacc ratio around 35Oe/(MV/m) must be designed).

This generally means a smaller bore radius

Trade-offs (Electropolishing, weak cell-to-cell coupling, etc)

KEK currently producing prototypes

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New Cavity Design

More radical concepts potentially offer greater benefits.

But require time and major new infrastructure to develop.

28 cell Super-structure

Re-entrant

single-cell achieved45.7 MV/m Q0 ~1010

(Cornell)

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ILC Siting and Civil Construction

• The design is intimately tied to the features of the site– 1 tunnels or 2 tunnels?– Deep or shallow?– Laser straight linac or follow earth’s curvature in

segments?

• GDE ILC Design will be done to samples sites in the three regions – North American sample site will be near Fermilab

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Fermilab ILC Civil Program

A Fermilab Civil Group is collaborating with SLAC Engineers and soon with Japanese and European engineers to develop methods of analyzing the siting issues and comparing sites.

The current effort is not intended to select a potential site, but rather to understand from the beginning how the features of sites will effect the design, performance and cost

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Draft 27-May-05

Conventional Facilities Site Considerations

1 Site impacts on critical science parameters 5 Construction Cost Impacts (cont.)

1AConfiguration (Physical Dimensions and

Layout)5

CClimate

.1 Usable Length and Width.

1Snowfall

.2 Flexibility for Adjustment of Alignment.

2Average Ambient temperature

.a Adaptable to Laser Straight.

3Average underground temperature

.b Adaptable to Earth Curvature.

4No of days rainfall

.3 Depth of Tunnel 5

DEnvironmental Restrictions

.4 Depth of Interaction Halls5

EAccessibility

.5 Accessibility to Tunnels5

FSite Utility Support & Installation

1BPerformance (Vibration and Stability

5GProximity of Soil Borrow and Disposal Areas

.1 Natural Vibration/Noise Sources5

HLocal Labor

.a Geologic Dynamic Properties.

1Construction Rate Index

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Strawman Final Focus

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Fermilab and the ILC

• Fermilab is rapidly developing a superconducting RF capability for the main linac design and development for the ILC.

• The Civil group at Fermilab is playing a central role in developing methods for understanding the siting and the interplay with the design.

• Plans are being developed to build a strong accelerator physics group at Fermilab for the ILC.

• There are many opportunities for involvement by the experimental community in the accelerator, the machine detector interfaces and the detector designs.--------------------------------------------------------------------------------------

• Fermilab can position itself very well to be able to succesfully bid to host the ILC, without mortgaging the rest of the program

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Remarkable progress in the past two years toward realizing an international linear collider:

important R&D on accelerator systems

definition of parameters for physics

choice of technology

start the global design effort

funding agencies are engaged

Many major hurdles remain before the ILC becomes a reality (funding, site, international organization, detailed design, …), but there is increasing momentum toward the ultimate goal --- An International Linear Collider.

Conclusions