Message from the Americas

Transcription

1 Message from the Americas G. Dugan, Cornell Univ. for the United States Linear Collider Steering Group (USLCSG) First ILC Workshop KEK, Tsukuba, Japan Nov. 13, 2004

2 Outline Perspectives on the ILC from the ILC-Americas Workshop (SLAC, Oct , 2004) Workshop overview Summary of issues, by accelerator system Interests and capabilities of universities and national laboratories in the Americas for accelerator R&D on the ILC Conclusions Message from the Americas 2

3 ILC-Americas Workshop This workshop, sponsored by the USLCSG and held at SLAC from Oct , 2004, was open to all parties in the Americas interested in participation in accelerator R&D for the ILC. There were 156 registered participants, from national laboratories, universities, and industry. This reflects the considerable interest and excitement in the American community at the prospect of participation in the ILC project. Proceedings are at project.slac.stanford.edu/ilc/meetings/workshops/us- ILCWorkshop/workshop.html Message from the Americas 3

4 ILC-Americas Workshop The goals of the workshop, and the working group structure, mirrored those of this international workshop. To set the stage for working group discussions, the opening plenary session of the workshop included review talks on two cold LC designs: TESLA, and the US Linear Collider Technology Options Study cold design. Subsequent slides here review the discussions and conclusions from this workshop. Message from the Americas 4

5 Overall system design considerations: Beam parameters Flexibility in parameter space desirable (essential) to meet luminosity goals. Consider reduction in beam power to ease design issues and reduce cost. Beam power (bunch charge): x2 reduction Issues: single bunch density/damage threshold, detector backgrounds Benefits: DR space charge reduced, ML wakes and beam tails reduced, e+ production easier, RF cost reduced, operating margins improved Disadvantages: luminosity loss by x4. Reduce bunch spacing in ML by x 2, increase bunch number by x 2, reduce IP beta value product β y β x by x4. Benefits: Compensate L loss from x2 bunch charge reduction Disadvantages: DR s kickers harder, collective effects worse, IP optics more complex, bunch length reduction also required. Bunch length reduction by x2 in the bunch compressor Benefits: reduce transverse wakes, reduce IP disruption, reduce β y for more L Disadvantages: HOM s worse, probably need more complex two-stage compressor, CSR needs checking Message from the Americas 5

6 Overall system design considerations: Cavity gradient Good reasons to go to higher gradients are to reduce costs or to meet specific site requirements Cost drivers for gradients higher than 35 MV/m seem weak Need to update cost curves and sensitivity to input parameters Need to perform 2/3-D optimization Lorentz detuning (proportional to square of gradient) gets more difficult above ~35 MV/m Dark current could be a problem Significant payback for higher Q 0 at given gradient Lower cryogenic losses Less dark current Message from the Americas 6

7 Overall system design considerations: USLCSG Availability and 1 vs 2 tunnels Pro - for 1 tunnel Cost!!! Need to understand actual delta in cost for the 2nd tunnel and the delta in cost to equalize availability. A near-surface tunnel with gallery (SLAC) may be the cheapest solution. Possible European safety regs that prevent entry to 2nd tunnel during operations. Con - against 1 tunnel Higher component availability required to achieve luminosity. US safety regs permit (desire?) 2nd tunnel for egress. Risk associated with commissioning due to limited access. Remnant fields near the SC cavities - trapped fields. Message from the Americas 7

8 Overall system design considerations: Commissioning 1.5 or 2.5 Tunnels for use with a dogbone DR? Pros: Avoid delays in commissioning, helps operations by separating DR & ML, avoids klystron & DR coupling, adds time to dump fault condition beam from DR s & BC Cons: Minor increase in phase 1 cost, adds length to the transfer lines Conventional source + civil construction for future undulator Pros: Could complete commissioning ~15 month earlier, no undulator (or required R&D), no undulator insertion with narrow bandpass, operations friendly due to separation of systems Cons: Target issues, larger production emittance (~x2), may need predamping ring Group consensus was that both of these are good ideas Message from the Americas 8

9 Electrons: Injectors-Sources Polarized e - source technology well in hand. R&D is needed to develop laser system to meet specs, improve photocathode, develop bunching system. Positrons: Positron source system needs better modeling, and technology development to support the design. The design is strongly coupled to the dynamic aperture of the positron damping ring. A conventional (electron-beam-driven) positron source is possible. An undulator-based system is radiologically cleaner and can produce polarized positrons. It has significantly more operational complexity than a conventional source. E-166 at SLAC will provide a demonstration of such a source. Message from the Americas 9

10 Injectors-Damping Rings Acceptance, vertical emittance and beam stability are issues. A wide range of design options are being considered: Circumferences of candidate rings vary between 3 km and 17 km; Use of pre-damping ring may provide benefits. Design choices are strongly coupled to e+ source and kicker performance: faster kicker will allow reduced circumference (subject to collective effects) conventional source produces larger emittance beam, which may require pre-damping ring to achieve necessary acceptance. Fast kicker: Basic choice: fast pulsed kicker or a (more exotic) RF device. Speed (2-20 ns), stability, impedance are all issues. Message from the Americas 10

11 Main Linacs Warm RF System Components Proof-of-principle demonstrations show TESLA designs can generate, transport and control required power. A good start has been made toward component industrialization, especially for the modulators. However, need better evaluation of component efficiency, serviceability and long-term reliability. Alternative designs were presented that are aimed at reducing cost and improving reliability, serviceability and functionality. GDE organization will need to decide on strategy for developing such designs based on likely project schedule and funding scenario. Message from the Americas 11

12 Main Linacs Linac Beam Dynamics Effectiveness of beam-based dispersion control likely limited by systematics, which may not be discovered in small scale tests. Meeting cavity alignment tolerances is non-trivial in a cryomodule and could be aided with HOM signal information. Damping of relevant dipole modes appears to be under control although not fully tested with latest HOM coupler design. Test Facilities JLab and FNAL have proposed to jointly lead a major program to develop US cavity and cryomodule production capability for the ILC in the next several years. FNAL also proposes to construct a cryomodule test area with beam capability (called SMTF) that initially tests a TESLA-built cryomodule. LANL has a large dedicated facility for cavity/cryomodule assembly and vertical tests. Message from the Americas 12

13 Cavities, Modules, and Cryogenics Status To address the charge, a spreadsheet was developed which categorized issues in this area as follows. Recommend action 1 solved 1 Acceptable as is 2 worth thought, review When needed Cost & effort 1 soon, under 2y 1 minor 1 minor Benefit expected 2 Mature design, needs refinement/ optimization 2 medium 5y 2 significant 2 medium 3 optimization required 4 really needs work 5 alternative ideas needed 6 optional or upgrade 3 Good concept needs significant work 3 long ~10y 3 major 3 significant 4 Significant concern may want to consider alternatives 4 critical 5 little done, must initiate Message from the Americas 13

14 Cavities, Modules, and Cryogenics Examples of the sorts of conclusions from spreadsheet: Cryomodule Cryomodule overall- optimization required, mature design, benefit to effort ratio large Cryomodule support alignment & vibration- really needs work, significant concern, needed in ~5 yr, benefit critical Cavity Cavity point design overall- worth review - optimization in 5 yr time scale, effort minor, benefit medium Cavity modifications- superstructure- significant effort, medium time scale~5 yr, significant benefit Cavity new ideas- new shapes & traveling wave, Major effort ~10 yr, significant benefit Fabrication & Processing- material pre-scanning- really needs work, significant effort, significant benefit other ideas- NbCu, Hydroforming, spinning, medium benefit; snow (CO 2 ) cleaning- significant benefit Tuner- really needs work-soon, effort significant, benefit significant Message from the Americas 14

15 Cavities, Modules, and Cryogenics-Industrialization We all recognize that it is urgent to get going on industrial partnership & tech transfer In particular - How does the cavity module engineering design and processing evolve toward industrial design & procedure Action item: A well planned workshop on how to proceed on industrialization program would be of great value Thoughts from Jlab: The National Lab s role is to transfer technology to industry Transfer process knowledge, not define how to do it. We need to form an industrialization team with members from all regions to: Define a list of the process steps as we know them today Start an industrial forum to open up discussion, court appropriate industry and start the educating process What problems, if any, need addressing to get an industrial effort started? One US Industry s (AES) thoughts on INDUSTRIAL PARTICIPATION SUMMARY DETERMINE WHICH COMPANIES ARE INTERESTED INVOLVE THEM EARLY IN A FUNDED TECH TRANSFER PROGRAM FUND THEM TO DEVELOP MANUFACTURING PLANNING AND TO CONDUCT R & D TO DEVISE MANUFACTURING TECHNIQUES REQUIRED FOR HIGH RATE PRODUCTION Message from the Americas 15

16 ILC BDIR design choices Crossing Angle head on (or very small horizontal or vertical crossing angle) 7-20 mrad, 35 mrad Final Doublet Technology Compact SC or PM quad, large bore SC L* e.g. 3, 4, 5 m Detector VD inner radius Choices of options in instrumentation, MPS, detector, collimation, beam stabilization Risk Mitigation Beam Delivery System Options Gamma-gamma Consequence of 35 mrad crossing angle on e+e- luminosity e-e- e+ polarized Above 1 TeV running Consequence of simultaneous running of both IRs Based on regional tasks lists, a unified task list is being put together at: ks/task_list.html Message from the Americas 16

17 Beam Delivery System Urgent work for next 8 months, to make progress on the most critical choices 7-20mrad Complete optics design, based on NLC BDS, but IR2: include upstream & downstream polarimetry and energy diagnostics, use compact SC quad IR1: extra drift before IP for γ dump, TDR SC quad Energy deposition 176ns 500GeV/beam & 337ns 250GeV/beam in BDS & extraction line (including fast feedback BPMs, electrostatic separator & septa.) IR2 IR1 Head-on (0,V0.3mrad,H2mrad) Optics studies & optimize L*, consumable or passive collimation Message from the Americas 17

18 Beam Delivery System Urgent work for next 8 months, to make progress on the most critical choices (continued) Electrostatic separator beam test Optimization of extraction lines: Head on, & 7-20mrad Engineering design studies of crab cavity with electronics Commitment to start long-lead-time test beam program (ESA, ATF,..) Comparative physics study related to x-ing angle and apertures (SUSY, VD radius) Civil engineering plan to upgrade one of IRs to ~35mrad when needed (footprint should support γγ from the start) Message from the Americas 18

19 Interests and capabilities in ILC R&D- US Labs Injectors System ANL Cornell FNAL JLab LBNL LLNL MSU SLAC e- source e+ source DR-design and simulation DR-Fast kickers Bunch compressor Message from the Americas 19

20 System Interests and capabilities in ILC R&D- US Labs Main Linacs and Beam Delivery Systems BNL Cornell FNAL JLab LANL LLNL MSU SLAC Main Linac: Modulators, RF distribution, LLRF Main Linac: Klystrons Beam dynamics, DR to IP Beam delivery systems Main Linacs: Cavities and Cryomodules ANL, BNL, Cornell, FNAL, JLab, LANL, LBNL, MSU, ORNL, SLAC Message from the Americas 20

21 ILC Cryomodule Fabrication and SMTF It is imperative to establish a US-based capability in the fabrication of high gradient superconducting accelerating structures. Assume the fabrication of ~20,000 ILC accelerating structures will be shared among the three regions. Significant U.S. SCRF expertise at: Argonne, Cornell, Fermilab, Jefferson Lab, Los Alamos, Michigan State Experience extends to both development and fabrication (e.g. SNS), but at gradients significantly below 35 MV/m JLab has made an SRF proposal to DOE for ILC cryomodule fabrication and technology transfer. The vehicle is the SMTF (Superconducting Module and Test Facility). The goal is to strengthen U.S. capabilities in high gradient and high Q superconducting accelerating structures in support of the International Linear Collider (ILC) and other accelerator projects of interest to U.S. laboratories. Collaboration of major DOE and NSF laboratories and universities, with international participation. Incorporate ILC, β<1 (Proton Driver, RIA), and CW test areas. Message from the Americas 21

22 ILC Cryomodule Fabrication and SMTF Expression of Interest submitted to Fermilab Director. Based on commitment to play a leading role following the cold decision. Provisional goal is fabrication and testing of three U.S. plus one European high gradient cryomodules by (in close coordination with the GDE). Cryomodule test facility to be constructed at Fermilab Interested partners: ANL, BNL, Cornell, FNAL, JLab, LANL, LBNL, MIT, MSU, NIU, ORNL, Pennsylvania, SLAC (, DESY, INFN, KEK) Concept of a possible evolution (ILC portion): Possible ILC test bed Message from the Americas 22

23 Interests in ILC R&D- Universities Two groups of universities in the US, the Linear Collider R&D Group (LCRD, DOE-funded), and the University Consortium for Linear Collider R&D (UCLC, NSF-funded), have proposed to do both accelerator and detector R&D for the International Linear Collider. Together, the two groups assembled 71 sub-proposals from 47 universities. The accelerator R&D proposals offer the opportunity for university-based physics and engineering groups to bring their considerable intellectual resources to bear on the challenges of the ILC. Accelerator R&D work, funded by both DOE and NSF, has been started at 12 universities in the past year. Message from the Americas 23

24 Universities-currently funded ILC accelerator R&D University Mass. Institute of Technology North Carolina A&T Ohio State University Univ. British Columbia Univ. Cal., Berkeley Univ. Cal., Davis Univ. Cal., Los Angeles Univ. Illinois Univ. New Mexico Univ. South Carolina, Univ. Tennessee, Princeton Univ. Wisconsin Vanderbilt University Topic Beam loss control in klystrons Damping ring studies Radiation-Hard Electronics Final quadrupole doublet stabilization RF BPMs Radiation damage studies Optical Diffraction Radiation RF breakdown, RF fast kicker schemes Coherent Synchrotron Radiation Undulator-based polarized positron production Polarized photocathode development Electro-optic and diffraction radiation Message from the Americas 24

25 Conclusions There is enormous interest, from a wide spectrum of national laboratories and universities in the Americas, in participation in the development of the ILC. These institutions and individuals have substantial expertise, intellectual resources and capabilities to contribute to the ILC. For these groups, the first steps in the discussion of how to proceed was undertaken at the ILC-Americas workshop, and will be continued here at the First ILC Workshop. We all look forward to a productive workshop as the first step in the formation of a global collaborative effort to design and build the ILC. Message from the Americas 25

26 Conclusions We pledge to work with the GDE central team to make the best possible use of our resources under their guidance. Message from the Americas 26