1. Steve Holmes Fermilab Indo-US Working Group Meeting August 5-6, 2004
International Linear Collider R&D, Technology Options and Collaboration
Steve Holmes
Fermilab
Indo-US Working Group Meeting
August 5-6, 2004

2. International Linear Collider View
An internationally constructed and operated electron-positron linear collider, with an initial center-of-mass energy of 500 GeV, has received strong endorsement by advisory committees in North America, Europe, and Asia as the next large High Energy Physics facility beyond LHC.
An international panel, under the auspices of ICFA, has established performance goals (next slide) as meeting the needs of the world HEP community.
An International Technology Recommendation Panel has now been convened under the auspices of ICFA with a charge to issue a technology recommendation by the end of 2004.

3. International Performance Specification
Initial maximum energy of 500 GeV, operable over the range GeV for physics running.
Equivalent (scaled by 500 GeV/s) integrated luminosity for the first four years after commissioning of 500 fb-1.
Ability to perform energy scans with minimal changeover times.
Beam energy stability and precision of 0.1%.
Capability of 80% electron beam polarization over the range GeV.
Two interaction regions, at least one of which allows for a crossing angle enabling gg collisions.
Ability to operate at 90 GeV for calibration running.
Machine upgradeable to approximately 1 TeV.

4. Performance Parameters
*JLC-C utilizes c-band for first 200 GeV, x-band for following 300 GeV of each linac

5. Current Round (ITRP) Contenders
TESLA
JLC-X/NLC

6. Linear Collider Performance Parameters Technology Requirements
Energy: 500 GeV, upgradeable to 1000 GeV
RF Structures
The accelerating structures must support the desired gradient in an operational setting and there must be a cost effective means of fabrication.
TESLA: MV/m
NLC/GLC: 65 MV/m (unloaded, 52 MV/m loaded)
RF power generation and delivery
The rf generation and distribution system must be capable of delivering the power required to sustain the design gradient
 Demonstration projects: NLC 8-pack test, NLCTA, TTF-I and II
Luminosity: 500 fb-1 in the first four years of operation
The specified beam densities must be produced within the injector system, preserved through the linac, and maintained in collision at the IR.
 R&D Facilities: ATF, ASSET, FFTB
Luminosity
Damping Rings

7. Linear Collider Technology Status NLC/GLC Structures

8. Linear Collider Technology Status NLC/GLC Structures
The NLC/GLC structure has evolved over the last several years in response to difficulties encountered with structure damage after several thousand hours of operations.
Length = 60 cm
Group velocity = 3%
New input couplers lowering peak fields
The resultant structure features:
Less stored energy, reduced ability for energy to flow within the cavity, and lower peak fields at the upstream end
Operational criterion for breakdown rate is based on:
99% availability with a 5 second recovery time (with 2% energy overhead)
 <0.4 breakdowns/structure/hour when operated at 60 Hz and the full (400 nsec) rf pulse width  Spec: <0.1 breakdowns/structure/hour
8 structures operating at NLCTA meet the gradient/breakdown spec

9. Linear Collider Technology Status NLC Test Accelerator (NLCTA)

10. Linear Collider Technology Status NLC/GLC Structures Performance (circa April 2004)
Unloaded Gradient (MV/m)
Breakdown Rate at 60 Hz (#/hr)
Average Rate Limit

11. Linear Collider Technology Status NLC/GLC Structures Performance
Manufacturer
Gradient (MV/m)
Trip Rate (#/hr)
H60vg4S17-FXD1A
FNAL
65.4
0.044
H60vg3S17-FXC5
64.4
0.025
H60vg4S17-3
KEK/SLAC
0.050
H60vg3S17-FXC3
0.031
H60vg3-FXB6
65.1
0.013
H60vg3-FXB7
67.0
0.132
H60vg4S17-1
63.5
0.060
H60vg3R17
SLAC
0.076
Average (23-July-04)
65.0
0.054
Average One Month Earlier
64.9
0.085
Average Two Months Earlier
0.163

12. Linear Collider Technology Status TESLA Structures
TESLA Linac RF Unit: 10MW klystron, 3 modules  12 cavities each
Total for 500 GeV: 572 units (includes 2% reserve for failure handling)

13. Linear Collider Technology Status TESLA Structures
The structure proposed for 500 GeV operation requires 24 MV/m.
Achieved in cavity production run
13,000 hours operation in TTF (not all modules at 24 MV/m)
The goal is to develop and install cavities capable of 35 MV/m for the energy upgrade to GeV.
Progress over the last several years has been in the area of surface processing and quality control.
Buffered chemical polishing
Electro-polishing
Several single cell cavities at 40 MV/m
Five nine-cell cavities at >35 MV/m
Dark current criteria established based on <10% increase in heat load
50 nA/cavity
BCP EP

14. Linear Collider Technology Status TESLA Structures
Vertical (low power test)
Comparison of low and high power tests (AC73)

15. Linear Collider Technology Status TESLA Structures: Dark Current
25 MV/m
35 MV/m
Dark Current (nA)
AC72
Radiation emissions of BCP and EP cavities (vertical test stand)
Gradient (MV/m)
Dark Current measurement on 8-cavity CM (ACC4)
~15 nA/cavity at 25 MV/m

16. Linear Collider Technology Status TESLA Structures
One electropolished cavity (AC72) has been installed into cryomodule ACC1 in TTF-II (March)
Cavity individually tested in the accelerator with high power rf.
Result: 35 MV/m
No field emission detected
Good results with LLRF and piezo-tuner
Calibrated with beam and spectrometer

17. Linear Collider Technology Status Summary: Structures
Eight NLC/GLC structures are operating per performance specification in the NLCTA.
Built by three different institutions on two continents
Keys to success were reducing length, reducing group velocity, improving input coupler design.
Five TESLA cavities have met the 35 MV/m performance specification
One has seen beam in a complete cryomodule
Key to success has been advancement in surface treatment procedures (BCP and EP)

18. Linear Collider Technology Status NLC/GLC Power Sources
75 MW PPM Klystron
(Nearly) full specification performance by two tubes
Full-specification induction modulator operating in support of the 8–pack test.
Congratulations to Daryl Sprehn and the XP3-4 crew, who demonstrated (so far) 2 hours of uninterrupted performance at 75 megawatts, 1.6 microseconds, 120 pps, 50 dB gain, 54% efficiency. The Klystron Department, maligned by some,  ignored by others, has come through again.
    Gaining recognition for building a useful collider component  in the rarefied atmosphere of a World Class Physics Laboratory is difficult, but for the record, in the prosaic community of Vacuum Electronics, this accomplishment might have earned the engineering equivalent of a Nobel Prize. Unfortunately, they don't have one. We shall continue, nevertheless, our earnest efforts to supply SLAC physicists with the klystrons they require, particularly since they cannot be obtained anywhere else in the world. Per ardua ad astra.

19. Linear Collider Technology Status NLC/GLC Power Sources
Power to loads 580 MW at 400 ns (design is 475 MW)
Operated 500 hours at ~500 MW
“8-pack” test at SLAC

20. Linear Collider Technology Status TESLA Power Sources
Three Thales TH1801 Multi-beam klystrons fabricated and test.
Efficiency = 65%
Pulse width = 1.5 msec
Peak power = 10 MW
Repetition rate = 5 Hz
Operational hours (at full spec) = 500 hours
Independent R&D efforts now underway at CPI and Toshiba
10 Modulators have been built
3 by FNAL and 7 by industry
7 modulators are in operation
10 years operation experience

21. Linear Collider Technology Status Summary: RF Sources
Modulators for both NLC/GLC and TESLA have been demonstrated and do not appear to have major issues.
Klystrons remain a challenge
Modest numbers of klystrons meeting specs exist for both NLC/GLC and TESLA.
R&D programs are continuing to develop units that can meet requirements in a reproducible manner.

22. Linear Collider Technology Status Damping Rings: ATF
NLC/GLC requirement met
electrons, single bunch
Performance consistent with intra-beam scattering
Need to move to multi-bunch; Better understanding of e-cloud;
Alternatives to TESLA dogbone

23. International Collaboration Organizational Models
Pre-construction
A description of a pre-construction organization is contained in the “Report of the ILCSC Task Force for Establishment of the International Linear Collider Global Design Initiative”
Global Design Initiative (GDI) responsible for development of the complete ILC engineering design and coordination of the associated R&D program.
Establish early 2005
Phase 1 = Conceptual Design Report
Phase 2 = Engineering Design
Construction and Operations
All regions of the world are looking at models for the international organization in the construction & operations phases.
Consensus evolving towards “host lab” + international organization. For an example see the ECFA study:

24. International Collaboration Present Organization
US LCSC
Asia/Pacific LCSC
ICFA
ITRP
Participating Laboratories and Universities
Government Agencies
ILCSC
European LCSC
ILC-TRC
Participating Laboratories and Universities
Participating Laboratories and Universities

25. International Collaboration Organizational Models: GDI Phase I
American Regional Team
Regional Team Director,
European Regional Team
Asia/Pacific Regional Team
US LCSC
Asia/Pacific LCSC
GDI Central Team
Central Team Director,
3 Regional Team Directors,
Chief Accelerator Scientist,
Chief Engineer, & staff
ICFA
Machine Advisory Committee
Participating Laboratories and Universities
Government Agencies
ILCSC
European LCSC
Participating Laboratories and Universities
Participating Laboratories and Universities

26. International Collaboration Organizational Models: GDI Phase II
ILCSC
European LCSC
The American Regional Team
Regional Team Director,
European Regional Team
Asia/Pacific Regional Team
US LCSC
Asia/Pacific LCSC
GDI Central Team
Central Team Director,
3 Regional Team Directors,
Chief Accelerator Scientist,
Chief Engineer, & staff
Group of Governments and Their Oversight Board
Machine Advisory Committee
Participating Laboratories and Universities
ICFA
International Collaboration Organizational Models: GDI Phase II
Committees on
Site Selection
Study of the international organization for ILC construction and operations
Regional Governments

27. Conclusions
Technologies required to support room temperature or superconducting rf-based linear colliders have made substantial progress over the last several years. Either could form the basis of a linear collider meeting the needs of the world HEP community.
We expect a technology decision before the end of the year.
Will allow consolidation of resources on the global level
Will trigger establishment of the GDI
A world organization is forming and will present multiple opportunities for participation:
Accelerating structures (in multiple world regions)
Simulations
Emittance preservation
Maintaining beams in collision
Damping rings
Collimation systems
Rf sources
Magnets, power supplies, controls, etc.