The International Linear Collider — The Technology Decision a

The International Linear Collider --- The Technology Decision a

The International Linear Collider — The Technology Decision a

Silberman, Steve, Contributing Editor has reference to this Academic Journal, PHwiki organized this Journal The International Linear Collider — The Technology Decision in addition to the Path to the Future Barry Barish OSTP 1-Dec-04 2001: The Snowmass Workshop participants produced the statement recommending construction of a Linear Collider to overlap LHC running. 2001: HEPAP, ECFA, ACFA all issued reports endorsing the LC as the next major world project, to be international from the start 2002: The Consultative Group on High-Energy Physics of the OECD Global Science Forum executive summary stated as the first of its Principal Conclusions: “The Consultative Group concurs with the world-wide consensus of the scientific community that a high-energy electron-positron collider is the next facility on the Road Map. “There should be a significant period of concurrent running of the LHC in addition to the LC, requiring the LC to start operating be as long as e 2015. Given the long lead times as long as decision-making in addition to as long as construction, consultations among interested countries should begin at a suitably-chosen time in the near future.” The Linear Collider April 2003: signed now by ~2700 physicists worldwide.: “Consensus Document” ) (To join this list, go to )

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Parameters as long as the Linear Collider September 30, 2003 Based on the physics goals in the consensus document, a group drew up parameters as long as the Linear Collider Ecm continuously adjustable from 200 – 500 GeV Luminosity in addition to reliability to allow Ldt = 500 fb-1 in 4 years following the initial year of commissioning Ability to scan at any energy between 200 in addition to 500 GeV; downtime to set up not to exceed 10% of actual data-taking time Energy stability in addition to precision below 0.1%; machine interface must allow energy, differential luminosity spectrum with that precision Electron polarization of at least 80% 2 intersection regions as long as experiments; one with crossing angle to enable gg collisions Allow calibration at the Z, but with lower luminosity in addition to emittance Parameters as long as the Linear Collider Baseline machine Any linear collider requires: Energy Luminosity Electron source Positron production Pre-injector accelerators Damping rings Bunch compressor rf power source/delivery Low level rf as long as rf control Main linacs Beam diagnostics: BPMs, movers Final focus system at IP Machine protection system rf b in addition to s: L-b in addition to (TESLA) 1.3 GHz l = 3.7 cm S-b in addition to (SLAC linac) 2.856 GHz 1.7 cm C-b in addition to (JLC-C) 5.7 GHz 0.95 cm X-b in addition to (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 in addition to final luminosity. Bunch spacing, train length related to rf frequency Damping ring design depends on bunch length, hence frequency Features of Specific Machine Realizations Frequency dictates many of the design issues as long as LC

The ITRP Members Jean-Eudes Augustin (FRANCE) Jonathan Bagger (USA) Barry Barish (USA) – Chair Giorgio Bellettini (ITALY) Paul Grannis (USA) Norbert Holtkamp (USA) George Kalmus (UK) Gyung-Su Lee (KOREA) Akira Masaike (JAPAN) Katsunobu Oide (JAPAN) Volker Soergel (Germany) Hirotaka Sugawara (JAPAN) David Plane – Scientific Secretary ITRP Schedule of Events Six Meetings RAL (Jan 27,28 2004) DESY (April 5,6 2004) SLAC (April 26,27 2004) KEK (May 25,26 2004) Caltech (June 28,29,30 2004) Korea (August 11,12,13) ILCSC / ICFA (Aug 19) ILCSC (Sept 20) Tutorial & Planning Site Visits Deliberations Exec. Summary Final Report Recommendation The Charge to the International Technology Recommendation Panel General Considerations The International Technology Recommendation Panel (the Panel) should recommend a Linear Collider (LC) technology to the International Linear Collider Steering Committee (ILCSC). On the assumption that a linear collider construction commences be as long as e 2010 in addition to given the assessment by the ITRC that both TESLA in addition to JLC-X/NLC have rather mature conceptual designs, the choice should be between these two designs. If necessary, a solution incorporating C-b in addition to technology should be evaluated. Note – We have interpreted our charge as being to recommend a technology, rather than choose a design

Our Process We studied in addition to evaluated a large amount of available materials We made site visits to DESY, KEK in addition to SLAC to listen to presentations on the competing technologies in addition to to see the test facilities first-h in addition to . We have also heard presentations on both C-b in addition to in addition to CLIC technologies We interacted with the community at LC workshops, individually in addition to through various communications we received We developed a set of evaluation criteria (a matrix) in addition to had each proponent answer a related set of questions to facilitate our evaluations. We assigned lots of internal homework to help guide our discussions in addition to evaluations Evaluating the Criteria Matrix We analyzed the technology choice through studying a matrix having six general categories with specific items under each: the scope in addition to parameters specified by the ILCSC; technical issues; cost issues; schedule issues; physics operation issues; in addition to more general considerations that reflect the impact of the LC on science, technology in addition to society We evaluated each of these categories with the help of answers to our “questions to the proponents,” internal assignments in addition to reviews, plus our own discussions Evaluation: Technical Issues The Panel evaluated the main linacs in addition to subsystems as long as X-b in addition to in addition to L-b in addition to to identify per as long as mance-limiting factors as long as construction in addition to commissioning. In general, the Panel found the LC R&D to be far advanced. The global R&D ef as long as t uncovered a variety of issues that were mitigated through updated designs. Evolution of RF Unit Scheme

Evaluation: Technical Issues For the warm technology, major subsystems were built to study actual per as long as mance. The KEK damping ring was constructed to demonstrate the generation in addition to damping of a high-intensity bunch train at the required emittance, together with its extraction with sufficient stability. The Final Focus Test Beam at SLAC was constructed to demonstrate demagnification of a beam accelerated in the linac. As a result, the subsystem designs are more advanced as long as the warm technology. Experimental Test Facility – KEK Prototype Damping Ring as long as X-b in addition to Linear Collider Development of Beam Instrumentation in addition to Control Evaluation: Technical Issues

Evaluation: Technical Issues In general, the cold technology carries higher risk in the accelerator subsystems other than the linacs, while the warm technology has higher risk in the main linacs in addition to their individual components. The accelerating structures have risks that were deemed to be comparable in the two technologies. The warm X-b in addition to structures require demonstration of their ability to run safely at high gradients as long as long periods of time. The cold superconducting cryomodules need to show that they can manage field emission at high gradients. For the cold, industrialization of the main linac components in addition to rf systems is now well advanced. Evaluation: Technical Issues Superconducting RF Linac Concept demonstrated in TESLA Test Facility Many cold technology components will be tested over the coming few years in a reasonably large-scale prototype through construction of the superconducting XFEL at DESY. A superconducting linac has high intrinsic efficiency as long as beam acceleration, which leads to lower power consumption. TESLA Test Facility Linac 240 MeV 120 MeV 16 MeV 4 MeV

Site power: 140 MW Sub-systems: 43MW Linac: 97MW Cryogenics: 21MW RF: 76MW 65% 78% 60% Beam: 22.6MW Injectors Damping rings Water, ventilation, Power Usage TESLA Design (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 New Cavity Shape as long as Higher Gradient TESLA Cavity A new cavity shape with a small Hp/Eacc ratio around 35Oe/(MV/m) must be designed. – Hp is a surface peak magnetic field in addition to Eacc is the electric field gradient on the beam axis. – For such a low field ratio, the volume occupied by magnetic field in the cell must be increased in addition to the magnetic density must be reduced. – This generally means a smaller bore radius. – There are trade-offs (eg. Electropolishing, weak cell-to-cell coupling, etc) Alternate Shapes

The Recommendation We recommend that the linear collider be based on superconducting rf technology This recommendation is made with the underst in addition to ing 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 in addition to cold linear collider communities, taking full advantage of the experience in addition to expertise of both (from the Executive Summary). The superconducting technology has several very nice features as long as application to a linear collider. They follow in part from the low rf frequency. Some of the Features of SC Technology The large cavity aperture in addition to long bunch interval reduce the complexity of operations, reduce the sensitivity to ground motion, permit inter-bunch feedback in addition to may enable increased beam current. The main linac rf systems, the single largest technical cost elements, are of comparatively lower risk. The construction of the superconducting XFEL free electron laser will provide prototypes in addition to test many aspects of the linac. The industrialization of most major components of the linac is underway. The use of superconducting cavities significantly reduces power consumption. TESLA Cost estimate500GeV LC, one e+e- IP 3,136 M€ (no contingency, year 2000) + ~7000 person years

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The ITRP Recommendation The ITRP recommendation was presented to ILCSC & ICFA on August 19 in a joint meeting in Beijing. ICFA unanimously endorsed the ITRP’s recommendation on August 20 in addition to J. Dorfan announced the result at the IHEP Conference The ITRP recommendation was discussed in addition to endorsed at FALC (Funding Agencies as long as the Linear Collider) on September 17 at CERN. The final report of ITRP was submitted to ILCSC on September 20 in addition to is now available. ICFA declared that the old names NLC, GLC, TESLA are now retired, in addition to the project will be called ILC. ILCSC is now setting up the “Global Design Initiative” (GDI), comprised of two parts (GDE [Ef as long as t] as long as up to agency approval in addition to funding; GDO [Organization] when agencies take ownership. The plan: A Central Team located at a National Laboratory Site, with Director, Chief Accelerator Scientist, Chief Engineer in addition to staff initially of 10-15. Three regional teams sited in Asia, Europe in addition to North America as determined by the regions. Each to have a Regional Director who join with the Central Team Director, Accel. Scientist in addition to Engineer to as long as m an overall directorate. Central Team to direct the work in addition to design choices. Actual design of subsystems to be done in the Regional Teams What Comes Next First ILC workshop to be held in KEK Nov. 13-15 – invite ~120 accelerator physicists from around the world to review systems designs as long as cold LC; discuss which aspects of the TESLA proposal should be kept, in addition to which need more thought, R&D; start to work on dividing R&D ef as long as t among regions in addition to labs. US workshop at SLAC Oct. 14 -16. KEK in addition to SLAC have embraced the new design ef as long as t in addition to are re-organizing to play critical roles. Fermilab will lead a consortium to build a superconducting rf test facility (in Meson East) with ANL, J-Lab, Cornell. They will build capability to fabricate in addition to test superconducting cavities, cryomodules outside DESY. DESY, CERN in addition to others won ‘EuroTeV’ grant from EU to study beam delivery systems, damping rings, polarized positron sources, beam diagnostics, integrated luminosity per as long as mance systems, metrology in addition to global accelerator network (remote operation). CERN role is critical – its main foci are launching LHC ( in addition to its upgrades) in addition to assuring its own future. R&D on CLIC will continue. However, in recent months, CERN has increasingly engaged in in addition to supported the move toward the TeV scale ILC. ILC machine design:

Fall 2002: ICFA created the International Linear Collider Steering Committee (ILCSC) to guide the process as long as building a Linear Collider. Asia, Europe in addition to North America each as long as med their own regional Steering Groups (Jonathan Dorfan chairs the North America steering group). Physics in addition to Detectors Subcommittee (AKA WWS) Jim Brau, David Miller, Hitoshi Yamamoto, co-chairs (est. 1998 by ICFA as free st in addition to ing group) International Linear Collider Steering Committee Maury Tigner, chair Parameters Subcommittee Rolf Heuer, chair (finished) Accelerator Subcommittee Greg Loew, chair Comunications in addition to Outreach Neil Calder et al Technology Recommendation Panel Barry Barish, chair (finished) Global Design Initiative organization Satoshi Ozaki, chair (finished) GDI central team site evaluation Ralph Eichler, chair GDI central team director search committee Paul Grannis, chair

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