The International Linear Collider

1. The International Linear Collider A broad international consortium is developing the design of an International Linear Collider to address critical scientific questions about the constitution of matter. We discuss the scientific case, recent R&D developments and progress toward international organization of the ILC.

2. The Terascale opportunity Experiments at accelerators and telescopes on the ground and in space have shown us that the Terascale (energies of trillions of electron volts) is very fertile ground for discovery. Our present theories fail there, and new phenomena must appear at the Terascale. Only experiment will tell us what these new phenomena will be. The Large Hadron Collider will enter the Terascale in 2007, and survey the terrain. New astrophysical experiments will tell us more about dark matter and dark energy. We need the ILC to discover what these new phenomena mean.

3. The ILC as an international effort It is widely understood that the ILC must be an international project involving Europe, Asia and the Americas. Substantial R&D is needed to validate the technical choices and determine the cost over the next few years. This is the primary near term challenge. The US, Europe and Asia are now working as equal partners in this R&D program, and in establishing the mechanisms for organizing a future project.

4. Compelling scientific questions The “Quantum Universe” report prepared by DOE & NSF identifies key questions in three major sectors that define the path to new understanding: http://www.science.doe.gov/hep/HEPAP/Quantum_Universe_GR.pdf Einstein’s dream Undiscovered principles, new symmetries? What is dark energy? Extra space dimensions? Do all forces become the same? The particle world New particles? What is dark matter? What do neutrinos tell us? Birth of universe How did the universe start? Where is the antimatter? The ILC will help answer most of these.

5. Why the Terascale? Accelerator and cosmological experiments in the past two decades have assembled a ‘Standard Model’. It works extremely well at the energies tested, but its intrinsic shortcomings point to dramatic discoveries at the Terascale. The keys to unification of forces, dark energy, dark matter and new symmetries of nature should be found there. We live in exciting times; never before we have been so knowingly ignorant about Nature! For 20 years, we have known that experiments at the Terascale will reveal new secrets of matter; we now have a strategy for uncovering them.

6. Understanding mass and inertia Our explanation for why particles resist acceleration (have inertia) is a Higgs field, pervading space and retarding particle motion. Past experiments tell us a Higgs particle should appear at the Terascale, and the LHC should discover it. The ILC will accurately measure its properties to explain its origin. The fractions of Higgs decays into known particles differ in various theories. ILC can measure these fractions accurately; LHC only poorly. Variants like supersymmetry modify these fractions from their SM values. Measuring the pattern at ILC will identify the origin of the Higgs field.

7. Discovering Dark Matter Our own and other galaxies show unseen dark matter, five times more prevalent than ordinary matter. Supersymmetry provides the most natural candidate dark matter particle, the neutralino. At the LHC the neutralino cannot be directly observed but the ILC will see it. Satellite experiments determine only the dark matter density; ILC measures the density and the particle mass and tells what the dark matter is. Note the relative precision of LHC and ILC on the mass of the dark matter particle.

8. Finding extra dimensions String theory suggests there are extra space dimensions, tightly curled up. Some particles could move into the extra dimensions. The ILC and LHC working together can determine the number of such extra dimensions and their size. New particles signifying extra dimensions may arise for ILC and LHC to study.

9. Unifying the forces At everyday energy scales, the 4 fundamental forces are quite distinct. At the Terascale, the Higgs field unifies the EM and Weak forces. LHC and ILC together will map the unified ‘Electroweak’ force. The Strong force may join the Electroweak at the Grand Unification scale. The ILC precision allows a view of this, and can help point the way to including gravity as well. go here sense whats happening here

10. The value of precision The LHC will survey the terrain and sense the existence of new phenomena. The ILC will make the precision measurements needed to give detailed understanding. Strength of forces → close but no cigar? Unification of forces? Precision matters! Energy →

11. Leadership in science and technology Scientific inquiry is a fundamental expression of our cultural values, and US leadership in science is a major national goal. The U.S. economy relies on a trained scientific manpower pool and technological expertise. Asking the basic questions (what is dark matter? are there extra dimensions? etc.) is often the hook that gets young people interested in science. For HEP only about 20% of the PhDs stay in fundamental research. The rest use their problem solving skills in industry and government.

12. Economic value • Fundamental research drives the economy: • 73% of papers cited in industrial patents are based on publicly financed research. • High Energy Physics had need of communication and ways to share documents, images etc. From this was born the World Wide Web which now exceeds $1T in 2001. • HEP needs massive parallel computing; it is the chief driver and user of the new GRIC computing and high speed network projects worldwide. • Particle physics develops accelerator technology used broadly in society. Over 17,000 accelerators worldwide now treat disease, create micro-electronics and aid industrial research. Benefits from the ILC science discoveries are unpredictable, but history suggests they will be real. The tools developed will likely have even more striking consequences.

13. Predicting economic value Our record of predicting the economic impact of basic science is poor: "Airplanes are interesting toys but of no military value"Marshal Ferdinand Foch, professor of strategy, Ecole Supérieure de Guerre "The wireless music box has no imaginable commercial value. Who would pay for a message sent to nobody in particular?" – David Sarnoff's associates, in response to his urgings for investment in the radio in the 1920s "I think there is a world market for maybe five computers." – Thomas Watson, chairman of IBM, 1943 Gladstone,Chancellor of the Exchequer, asking about Faraday’s discoveries of electric induction (leading to the electric generator, and the basis for EM waves): “But after all, what use is it?” Faraday:“I do not know sir, but soon you will be able to tax it.”

14. Relation to other scientific initiatives Particle accelerators are among the most significant exports from HEP to other areas of science and technology. • The ILC superconducting rf technology will have strong impacts upon the future of: • Synchrotron light sources(materials science, structural biology, environmental science, femtosecond chemistry etc.) • Energy recovery linacs(next generation light sources, spallation neutron sources for materials research and heavy ion colliders for nuclear research) • Radioactive isotope accelerators(nuclear science and astrophysics)

15. electron sources collision point positron source e- damping ring e+ damping ring electron linac positron linac 44 km What is the ILC? Two 20 km long linear accelerators, bringing beams of electrons and positrons into collision in a spot only nanometers across at energies up to 1 Tera electron volts (trillion electron volts). Powerful electric fields in superconducting cavities, in synchronization with the particle’s motion, provide the acceleration.

16. International consensus 2001 -2: Panels in US, Europe and Asia recommend ILC as top priority for world’s next high energy facility. OECD Science Ministers concur. International Steering Committee (ILCSC) formed to guide the effort. 2003: Over 2700 physicists from around the world sign ‘consensus document’, demonstrating an important convergence of the vision for the future. 2004: The international HEP community made the key choice between rival design technologies. Proponents of both techniques enthusiastically joined together for a common design effort on the International Linear Collider.

17. Recent ILC progress 2005: International Global Design group (GDE) established to lead the international design effort with Barry Barish (from Cal Tech) as Director. The GDE organization (50 scientists, 20 FTE) includes accelerator scientists, cost engineers, civil engineers, communications experts and detector physicists from each region (US, Europe, Asia). The GDE is preparing the design, conducting R&D and developing common tools that will serve the global effort as well as adapt to regional needs. In August 2005, 670 physicists and engineers from around the world gathered in Snowmass Colorado to initiate the ILC design effort.

18. The near term plan • Baseline configuration will be established by end 2005, based on decisions on ~50 key issues. Alternate choices identified for further R&D to lower cost or reduce risk. • Prepare a Reference Design by end 2006, with cost estimate for representative sites. • In 2007- 2008, proceed with technical design, site discussion, formulation of management structure. www.linearcollider.org

19. Current GDE activities • ILC is at present an R&D effort that seeks to: • Provide the scientific validation (and the relation of ILC to LHC) • Estimate costs to demonstrate affordability • Conduct R&D needed for cost reduction and risk control • Establish the industrial base needed for the full project • Evaluate potential sites • Prepare the detailed technical design needed for project approval by governments • Working with governments, develop the necessary management structures

20. max luminosity { head room operating plane parameter 2 parameter 1 Parametric design Use a parametric approach to machine design to allow a range of operational parameters to give flexibility for coping with unexpected problems. Example of parametric approach to cost optimization: higher gradient field cuts civil and cavity costs but increases cryogenic costs. [The minimum is quite shallow – 4% cost decrease going from 30 to 40 MV/m.] Cost → Accelerating electric field→

21. The ILC Roadmap 2005 2006 2007 2008 2009 2010 … Global Design Effort Project LHC Physics Baseline configuration Reference Design Technical Design ILC R&D Program Expression of Interest to Host International Mgmt

22. Learning from other large projects • There are many lessons from other large projects: • ITER guidance for international scientific projects • Learn from the failure of the SSC • Design and management techniques from NASA & very large telescope projects • Retain flexibility to allow use of technical advances

23. SSC lessons • The project should be international from the outset. • The project should have wide support within the scientific community. • Costing must be done from the beginning according to agreed upon rules; it should include some way of handling contingency costs, escalation, commissioning and operations costs and indirect costs. • Strong management and good organization is essential. For the ILC, 1 and 2 are in place. 3 is part of the GDE plan. We recognize the importance of 4 and are working to assure.

24. ITER lessons ITER is on the same scale as the ILC; we must profit from the ITER experience. Variable costing methods in different countries, currency fluctuations, effect of in-kind contributions require a sharing of responsibility based upon VALUE ASSESSMENTS (the ITER Unit). Shares in the project are based on these value units. Completion of agreed work packages must include the necessary flexibility needed to deliver them. Thus national assessments of the local cost (in $, €, ¥, ₤ …) must be done carefully. The obligations of partners for the duration of the project must be agreed upon; the protocols for establishing these vary among countries.

25. The International Linear Collider • Exploring the deepest questions about the structure of matter, energy, space & time • An opportunity for promoting the scientific and technological leadership of the US • A vehicle for worldwide economic and scientific growth • The key need now is for R&D to validate the ILC and define its cost