Status of the ILC Accelerator Design Barry Barish

Status of the ILC Accelerator Design Barry Barish, Nick Walker for the entire ILC machine community 2 nd ILC Workshop – Snowmass, Colorado 26. 08. 2005 2. 08. 2005 Nick Walker - 2 nd ILC Workshop Snowmass - Colorado

The Year After ‘Unification’ • 1 st ILC workshop at KEK November 2005 • ILCSC forms 5 technical WG + 1 communications and outreach WG • • • 2. 08. 2005 WG 1 Parameters & General Layout WG 2 Main Linac WG 3 Injectors WG 4 Beam Delivery & MDI WG 5 High gradient SCRF WG 6 Communications Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 2

The Year After ‘Unification’ Goals of the 1 st Workshop 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 3

The Year After ‘Unification’ Birth of the GDE and Preparation for Snowmass • • • WG 1 Parms & layout WG 2 Linac WG 3 Injectors WG 4 Beam Delivery WG 5 High Grad. SCRF WG 6 Communications 2. 08. 2005 • • WG 1 LET beam dynamics WG 2 Main Linac WG 3 a Sources WG 3 b Damping Rings WG 4 Beam Delivery WG 5 SCRF Cavity Package WG 6 Communications Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 4

The Year After ‘Unification’ Birth of the GDE and Preparation for Snowmass • • • WG 1 Parms & layout WG 2 Linac WG 3 Injectors WG 4 Beam Delivery WG 5 High Grad. SCRF WG 6 Communications Introduction of Global Groups transition workshop → project 2. 08. 2005 • • • • WG 1 LET beam dynamics WG 2 Main Linac WG 3 a Sources WG 3 b Damping Rings WG 4 Beam Delivery WG 5 SCRF Cavity Package WG 6 Communications GG 1 Parameters & Layout GG 2 Instrumentation GG 3 Operations & Reliability GG 4 Cost Engineering GG 5 Conventional Facilities GG 6 Physics Options Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 5

2 nd ILC Workshop (Snowmass) Global Group • • • WG 1 LET bdyn. WG 2 Main Linac WG 3 a Sources WG 3 b DR WG 4 BDS WG 5 Cavity Provide input • • • Technical sub-system WG GG 1 Parameters GG 2 Instrumentation GG 3 Operations & Reliability GG 4 Cost & Engineering GG 5 Conventional Facilities GG 6 Physics Options 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 6

Goals of the 2 nd Workshop • Continue process of making a recommendation on a Baseline Configuration • Identify longer-term Alternative Configurations • Identify necessary R&D – For baseline – For alternatives This workshop has been a major step towards these milestones • Priorities for detector R&D 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 7

Baseline / Alternative: some definitions • Primary GDE Goal: – Reference Design Report including costs end 2006 • Intermediate goal (follows from primary) – Definition of a Baseline Configuration by end of 2005 • Will be designed to during 2006 • Will be basis used for cost estimate • Will NOT be the machine we will build 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 8

Baseline / Alternative: some definitions Baseline: a forward looking configuration which we are reasonably confident can achieve the required performance and can be used to give a reasonably accurate cost estimate by mid-end 2006 (→ RDR) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 9

Baseline / Alternative: some definitions Alternate: A technology or concept which may provide a significant cost reduction, increase in performance (or both), but which will not be mature enough to be considered baseline by mid-end 2006 Note: Alternatives will be part of the RDR Alternatives are equally important 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 10

Baseline Configuration Document • Our ‘Deliverable’ by the end of 2005 • A structured electronic document – Documentation (reports, drawings etc) – Technical specs. – Parameter tables –… • A ‘printable / readable’ summary document (~100 pages) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 11

Structure of the BCD Summary-like overview for those who want to understand the choice and the why Technical documentation of the baseline, for engineers and acc. phys. making studies towards RDR 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 12

Alternatives Section(s) Note ACD is part of the BCD 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 13

Towards the BCD 2. 08. 2005 Nick Walker - 2 nd ILC Workshop Snowmass - Colorado

The Hard Questions 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 15

The Hard Questions Critical choices: luminosity parameters & gradient 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 16

The Hard Questions Many questions are interrelated and require input from several WG/GG groups 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 17

Luminosity Parameters • nominal 500 Ge. V luminosity: 2× 1034 cm-2 s-1 • We want to design to a parameter ‘space’ • Keep a range of options open – Flexibility – Risk mitigation • Current sets represent trade-offs between sub-systems – Particularly Damping Ring Beam Delivery 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 18

Nominal nom N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 1010 2 2820 mm, nm 10, 40 cm, mm 2, 0. 4 nm 655, 5. 7 18. 5 % 2. 2 mm 300 MW 11 50% IP vertical emittance 20 nm (100%) emittance dilution budget from damping ring [TDR allowed 50%] Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 19

Low Bunch Charge N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 nom low N 2 1 2820 5640 mm, nm 10, 40 10, 30 cm, mm 2, 0. 4 1. 2, 0. 2 1010 nm 655, 5. 7 495, 3. 5 18. 5 10 % 2. 2 1. 8 mm 300 150 MW 11 11 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 20

sy = 8 nm N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 nom low N lrg Y 2 1 2 2820 5640 2820 mm, nm 10, 40 10, 30 12, 80 cm, mm 2, 0. 4 1. 2, 0. 2 1, 0. 4 1010 nm large IP vertical emittance 655, 5. 7 495, 3. 5 495, 8 18. 5 10 28. 6 % 2. 2 1. 8 2. 4 mm 300 150 500 MW 11 11 11 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 21

Low Average Power N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 nom low N lrg Y low P 2 1 2 2 2820 5640 2820 1330 mm, nm 10, 40 10, 30 12, 80 10, 35 cm, mm 2, 0. 4 1. 2, 0. 2 1, 0. 4 1010 nm 1, 0. 2 reduced bunch number compensation 655, 5. 7 495, 3. 5 495, 8 452, 3. 8 18. 5 10 28. 6 27 % 2. 2 1. 8 2. 4 5. 7 mm 300 150 500 200 MW 11 11 11 5. 3 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 22

Low Average Power N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 nom low N lrg Y low P 2 1 2 2 2820 5640 2820 1330 mm, nm 10, 40 10, 30 12, 80 10, 35 cm, mm 2, 0. 4 1. 2, 0. 2 1, 0. 4 1010 nm 1, 0. 2 reduced bunch number compensation 655, 5. 7 495, 3. 5 495, 8 452, 3. 8 18. 5 10 28. 6 27 % 2. 2 1. 8 2. 4 5. 7 mm 300 150 500 200 MW 11 11 11 5. 3 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 23

Pushing the Envelopes N nb ex, y bx, y sx, y Dy d. BS sz Pbeam 2. 08. 2005 nom low N lrg Y low P High L 2 1 2 2820 5640 2820 1330 2820 mm, nm 9. 6, 40 10, 30 12, 80 10, 35 10, 30 cm, mm 2, 0. 4 1. 2, 0. 2 1, 0. 4 1, 0. 2 1010 nm 543, 5. 7 495, 3. 5 495, 8 452, 3. 5 18. 5 10 28. 6 27 22 % 2. 2 1. 8 2. 4 5. 7 7 mm 300 150 500 200 150 MW 11 11 11 5. 3 11 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 24

Example of Discussions Workshop allowed open discussion of new ideas and proposals 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 25

Gradient • Baseline recommendation for cavity is standard TESLA 9 cell • Alternatives (energy upgrade): – Low-loss, – Re-entrant – superstructure 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 26

Gradient recommendation (WG 5) • 8 km @ 31. 5 MV/m → 250 Ge. V • +7 km @ 36 MV/m → 500 Ge. V Tunnel length for one 500 Ge. V linac (8+7)/0. 7 21 km 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 27

Gradient (WG 5 Justification) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 28

Gradient (WG 5 Justification) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 29

single-cell measurements (in nine-cell cavities) TESLA EP status Results from KEK-DESY collaboration must reduce spread (need more statistics) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 30

Cavity Fabrication 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 31

Alternative Fabrication techniques 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 32

Improved Processing (Electropolishing) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 33

Improved Cavity Shapes 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 34

Cavity R&D Fabrication from large grain Nb discs May remove the need for electropolishing ( cost!) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 35

Conventional Facilities and Siting Milestone One: Snowmass 2005 Conference Successfully Initiate the Global Civil and Siting Effort Complete Comparative Site Assessment Matrix Format Milestone Two: December, 2005 Identify Regional Sample Sites for Inclusion into the Baseline Configuration Document Milestone Three: December, 2006 Complete Conventional Facilities and Siting Portion of the Reference Design Document 8. 19. 05 2. 08. 2005 V. Kuchler Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 2 of 8 36

Sample Site Study Conventional Facilities Site Considerations- 16 Aug. 2005 1. Site Impacts on Critical Science Parameters Description: This sub-heading will evaluate site-specific factors that affect critical science parameters. Consideration: The site should permit the highest level of research productivity and overall effectiveness at a reasonable cost of construction and operation and with a minimal impact on the environment. 1 A. Configuration (Physical Dimensions and Layout) The topography and geology of a site strongly influences machine configuration, tunnel alignment, tunnel depth, tunnel access and penetrations as well as the flexibility for design optimization options. 1 B. Performance (Vibration and Stability) Micro-seismic ground motion and cultural noise (man-made vibrations) may affect the operations of the beamline apparatus. To minimize impact upon beam position, the ILC beam line should be oriented to minimize ground waves at a given site. A quiet site which has low levels of micro-seismicity and cultural noise will avoid the need for passive or active damping systems to achieve required stability during operation. 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 37

Conventional Facilities and Siting Outstanding Issues with Direct Impact on CFS Progress that will Require Further Discussion and Resolution with Other Working Groups 1 Tunnel vs 2 Tunnel Laser Straight vs Curved or Segmented Shape and Length of Damping Rings Shape and Configuration of Sources 1 vs 2 Interaction Regions 8. 19. 05 2. 08. 2005 V. Kuchler Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 6 of 8 38

Conventional Facilities and Siting • 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 – Japan and Europe are to determine sample sites by the end of 2005 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 39

1 or 2 Linac Tunnels • Tunnel must contain – Linac Cryomodule – RF system – Damping Ring Lines • Save maybe $0. 5 B • Issues – – Maintenance Safety Duty Cycle Availability/Commissioning (studies currently favour 2) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado e l p m a x e 40

Possible Tunnel Configurations • 2. 08. 2005 One tunnel or two, with variants? Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 41

ILC Civil Program Civil engineers from all three regions working 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 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 44

Baseline Klystrons 10 MW MBK 1. 5 ms pulse 65% efficiency Thales 2. 08. 2005 CPI Toshiba Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 45

Improved Klystrons (? ) 5 MW Inductive Output Tube (IOT) 10 MW Sheet Beam Klystron (SBK) Low Voltage 10 MW MBK Voltage e. g. 65 k. V Current 238 A More beams Parameters similar to 10 MW MBK Output Perhaps use a Direct Switch Modulator Klystron IOT SLAC 2. 08. 2005 Drive CPI Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado KEK 46

Klystron power RF Distribution Cavities (12) TESLA TDR and XFEL solution (TTF) Uses many circulators to protect klystron from reflected power (and isolate couplers) 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 47

Klystron power RF Distribution Possible improvement Two level division Cavities (12) • Expensive circulators eliminated • Fewer types of hybrid couplers • Proper phasing causes reflections from pairs of cavities to be directed to loads • Small increase risk to klystron 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 48

Modulators (115 k. V, 135 A, 1. 5 ms, 5 Hz) (~ 2 m Long) Pulse Transformer Style 2. 08. 2005 Operation: an array of capacitors is charged in parallel, discharged in series. Will test full prototype in 2006 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 49

Damping Rings: Three variants 6 km 3 km 2. 08. 2005 17 km ‘dogbone’ Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 50

Damping Rings higher Iav smaller circumference (faster kicker) bunch train compression 300 km 20 km 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 51

Damping Rings: Recommendation • Not Yet! • Systematic analysis of all rings being made – – – Dynamic aperture Emittance performance (tolerances) Electron cloud Fast ion instability … • Positive R&D on fast kickers will allow smaller circumference than TESLA dogbone • Recommendation to be made before the BCD 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 52

Positron Source • Conventional Source Backup solution – Single target solution exists – Close to (at? ) limits – Independent source • Undulator source – – – Uses main electron beam (150 -250 Ge. V) Coupled operation Efficient source Relatively low neutron activation Polarisation • Laser Compton source – – – Independent polarised source Relatively complex source Multi-laser cavity system required Damping ring stacking required Large acceptance ring (for stacking) Needs R&D 2. 08. 2005 WG 3 a recommendation for baseline Will need ‘keep alive source’ due reliability issues WG 3 a recommended alternative. Strong R&D programme needed Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 53

Positron Source 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 54

Beam Delivery, MDI Strawman solution (BCD recommendation) Appears to work for nearly all suggested parameter sets: Exceptions: • 1 Te. V high-luminosity (new parameter set suggested for 20 mrad) • 2 mrad extraction has problems with high disruption sets 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 55

Beam Delivery System • Baseline recommendation – Two IRs (20 mrad, 2 mrad) + 2 detectors – Longitudinally separated halls • Alternatives 1 – Two IRs (20 mrad, 2 mrad) + 2 detectors with – No longitudinal separation • Alternative 2 – Single IR with push-pull capability for two detectors (cost favoured) • 10 -15 mrad crossing angle also being considered 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 56

What I missed! 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 57

Transition to the GDE • Three regional directors have identified GDE members (with agreement from BB) • 49 (current) members representing approximately 20 FTE • GDE group consists of – – – 2. 08. 2005 core accelerator physics experts 3 CFS experts (1 per region) 3 costing engineers (1 per region) 3 communicators (1 per region) representatives from WWS Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 58

Chris Adolphsen, SLAC Jean-Luc Baldy, CERN Philip Bambade, LAL, Orsay Barry Barish, Caltech (the boss) Wilhelm Bialowons, DESY Grahame Blair, Royal Holloway Jim Brau, University of Oregon Karsten Buesser, DESY Elizabeth Clements, Fermilab Michael Danilov, ITEP Jean-Pierre Delahaye, CERN (EU dep. dir. ) Gerald Dugan, Cornell University (US dir. ) Atsushi Enomoto, KEK Brian Foster, Oxford University (EU dir. ) Warren Funk, JLAB Jie Gao, IHEP Terry Garvey, LAL-IN 2 P 3 Hitoshi Hayano, KEK Tom Himel, SLAC Bob Kephart, Fermilab Eun San Kim, Pohang Acc Lab Hyoung Suk Kim, Kyungpook Nat’l Univ Shane Koscielniak, TRIUMF Vic Kuchler, Fermilab Lutz Lilje, DESY 2. 08. 2005 Tom Markiewicz, SLAC David Miller, Univ College of London Shekhar Mishra, Fermilab Youhei Morita, KEK Olivier Napoly, CEA-Saclay Hasan Padamsee, Cornell University Carlo Pagani, DESY Nan Phinney, SLAC Dieter Proch, DESY Pantaleo Raimondi, INFN Tor Raubenheimer, SLAC Francois Richard, LAL-IN 2 P 3 Perrine Royole-Degieux, GDE/LAL Kenji Saito, KEK Daniel Schulte, CERN Tetsuo Shidara, KEK Sasha Skrinsky, Budker Institute Fumihiko Takasaki, KEK Laurent Jean Tavian, CERN Nobu Toge, KEK Nick Walker, DESY (EU dep. dir. ) Andy Wolski, LBL Hitoshi Yamamoto, Tohoku Univ Kaoru Yokoya, KEK Nick Walker - 2 nd ILC Workshop Snowmass - Colorado 49 - members 59

Towards a final BCD we are here August September October November 2005 December WW/GG summaries Response to Himel list (40 questions) all documented ‘recommendations’ publicly available on www (request community feedback) review by BCD EC BCD Executive Committee: Barish Dugan, Foster, Takasaki (regional directors) Raubenheimer, Yokoya, Walker (gang of three) 2. 08. 2005 BCD EC publishes ‘strawman’ BCD public review Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado Frascati GDE meeting 60

BCD review process • BCD executive committee will monitor BCD progress – Review WG/GG summary write-ups (recommendations) – Review each question on the Himel list • BCD EC will identify needed additional input – additional (missing) expertise (members) of the GDE • Strawman BCD available mid-November • Presentation of strawman BCD at Frascati GDE meeting (Dec. 10 -12) • Final agreed BCD to be documented • Final BCD becomes property of ‘change control board’ end 2005 / beginning 2006 • Then the real hard work starts 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 61

Final Comments • A great deal of work has been accomplished this workshop – big thanks to all the WG/GG conveners and participants • We are close to having the necessary recommendations for the BCD – Still many ‘details’ to be worked out • We must keep up this momentum until the GDE Frascati meeting – publication of the BCD will be the GDE’s first real milestone • The GDE must start to plan for the hard work of preparing the Reference Design Report (RDR), due the end of 2006. 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 62

Final Comments (cont. ) • The ILC project has attracted many of the best accelerator engineers and physicists in the world! • Let us (continue to) all work together to achieve this great adventure. 2. 08. 2005 Nick Walker - 2 nd ILC Workshop - Snowmass - Colorado 63