The LC Machine Scope Documents: Mark Oreglia The University of Chicago

1. This will be a very brief report on the various scope activities • US Scope paper • European Scope draft • International Parameters Committee … very recent progress! The LC Machine Scope Documents: Mark Oreglia The University of Chicago M. Oreglia

2. Brau’s Alphabet Soup • To facilitate basic actions, 3 regions generate inputs: • America (HEPAP), Asia (ACFA), Europe (ECFA) • Regional groups each decide what LC parameters they each want • Then the International Steering Ctte takes this regional input, makes choices and takes political actions • Organizations: • International Linear Collider Steering Committee (ILCSC) • WW parameters committee • Worldwide Study of Physics & Detectors … 3 regional ctte’s • LHC/LC Physics study group (G. Weiglein) • US LC Steering Group (USLCSG) • Led by lab directors (Dorfan currently chairing) • American Linear Collider Physics & Detector Group (ALCPG) • Executive Ctte M. Oreglia

3. Machine Scope Documents • The “scope papers” are the requisite white papers needed to justify a new machine • The American and European papers have been issued • An ILC committee has been established to unify them • Asian input via this ILC Committee • Our precursor: • “Item 2 of the ILCSC Mandate calls for an early consensus on the scope of the facility in terms of physics capability. Thus it seemed natural to think about a subcommittee that would aid this function…. • This is the “consensus document” you were asked to consider signing to show community support for LC • http://sbhep1.physics.sunysb.edu/~grannis/wwlc_report.html M. Oreglia

4. Intent of the US Scope Paper • In June the USLCSG asked that the ALCPG write a white paper describing the physics-motivated machine parameters … • A document the machine planners can start using now • A document to define the goals before funding agencies • The Executive Committee used the “Orange book” and input from the working groups to: • define the minimal acceptable parameters • prioritize options • not an instrument to choose technology “Design Considerations for an Int’l LC” (http://blueox.uoregon.edu/~lc/scope.ps) M. Oreglia

5. Document Structure • Brief (12 pgs) and to the point • Summarizes the physics driving the parameters • Does not suggest a technology choice • … and no parameters suggest one • Authored by the ALCPG Executive Ctte + some key WG leaders • Drafts were reviewed by the USLCSG and all the WG leaders; penultimate draft was presented at Arlington • After final approval by the USLCSG, the US scope paper was released and will be considered the US input to the International Scope Ctte M. Oreglia

6. Initial Energy and Luminosity • Initial Energy: 200-500 GeV at 2×1034 cm-2s-1 • ... actually, we also state this in integrated lumi • Higgs: • Precision EW Higgs range mh=115-200 GeV • peaks energy suggests E ~ 400 GeV • H self-coupling: need ~ 500 GeV • WW fusion production requires 500 GeV • 5% Statistics for precision measurements • threshold scan requires longer run • SUSY: • pair production grounds for emphasizing 500 GeV and higher • Extended Models • Same luminosity serves well in large class of models • Polarization: • 80% on e- initially. Positron polarization later??? M. Oreglia

7. Ultimate Energy • A difficult item to justify; 800 GeV? 1000 GeV? 1300 GeV? • I think all of us are convinced ≥1 TeV is required • SUSY spectra in many benchmarks • Current views on SSB from lattice calculations • Higgs self coupling is a must-do! • MSSM Higgs spectra • Dynamical SB scenarios are high-energy scale • The LC will be the frontier machine after LHC • we make a strong case for E upgrades/longevity • table of physics-return versus E and integrated lumi • Thus, a case is made for > 1 TeV upgrades • Perhaps energy – luminosity tradeoff is the answer here M. Oreglia

8. Interaction Regions • We make the case for 2 interaction halls (but not 2 detectors!) • The obvious benefits from 2 detectors • cross checking; competition; broader physics; specialization • Efficient staging area for repair or specialized function • Necessary for gg, e-e- options M. Oreglia

9. Z Running • Calibration: This is STILL one of the debated points! • How much calibration running is necessary at the Z? • Good calibration essential for precision EW • Is this an absolute requirement? How much? • Can’t we use Z,W production at higher energies? • Working Groups: now is STILL the time for more work! • Giga-Z remains an upgrade option • Depends on what new physics is discovered • Requires positron polarization, extreme E resolution • Not discussed at length • Despite uncertainties, a scenario for Z-pole, WW running must be there! M. Oreglia

10. Collision Options • We discuss the highly desirable options gg, e-e- • Strongly endorsed and impacts IP design • Physics: • Production cross sections • Hgg coupling • Measure CP assignments • Rare decays • Sensitivity to extended models M. Oreglia

11. How Machine Parameters Affect the Detector • Crossing angle: • Beam instrumentation possible or greatly enhanced • Better average energy measurement • Polarization measurement • Beam halo and stay-clear affect detector • Beamstrahlung: • Warm/cold really pretty similar here • argument of larger e+e- background not compelling • Bunch structure and timing: • Warm/cold have major difference in duty cycles, readout time. • Pros and cons for both technologies; • probably no showstoppers M. Oreglia

12. The ECFA Scope Document • Physics arguments for the parameter values may be found in the TESLA TDR, in the contributions to the ECFA/DESY Extended Study and in the document from the World Wide Study Group ("Understanding Matter, Energy, Space and Time: The Case for the e+e- Linear Collider" • Phase 1 • A cms-energy range of 91 to 500 GeV • At 500 GeV instantaneous luminosity and reliability sufficient to deliver a total of some 500 fb-1 in the first 4 years of running • tunnel and floorspace available for two interaction regions, at least one of them with finite crossing angle, and at least one fully functional detector • both interaction regions allowing the same energy range and luminosity for e+e- collisions • 80% electron polarisation • capability to run e-e- experiments • possibility to get to higher energies (some 750 GeV cms) without increasing cooling and RF power, i.e., with reduced luminosity at increased gradient • Priorities on the options listed below will depend on the results obtained from LHC and the first phase LC. • Options • positron polarisation of some 60% • high luminosity 'low energy' running (i.e. running at the Z-pole and WW threshold) with at least 50 fb-1/year and with e- and e+ polarisation at the Z-pole • cms-energy upgradeable to approximately 1 TeV, but at least 800 GeV • integrated luminosity approximately 500 fb-1/year at the high energy • γγ, eγ laser facility with Lumi(γγ) = Lumi(e+e-)/2 M. Oreglia

13. Mandate of the ILCSC (Chair: Tigner) • 1. Engage in outreach, explaining the intrinsic scientific and technological • importance of the project to the scientific community at large, to industry, to • government officials and politicians and to the general public. • Engage in defining the scientific roadmap, the scope and primary parameters for machine and detector.It is particularly important that the initial energy, the initial operations scenario and the goals for upgradability be properly assessed. • 3. Monitor the machine R&D activities and make recommendations on the • coordination and sharing of R&D tasks as appropriate. Although the accelerator • technology choice may well be determined by the host country, the ILCSC should • help facilitate this choice to the largest degree possible. • 4. Identify models of the organizational structure, based on international • partnerships, adequate for constructing the LC facility. In addition, the ILCSC • should make recommendations regarding the role of the host country in the • construction and operation of the facility. • 5. Carry out such other tasks as may be approved or directed by ICFA. M. Oreglia

14. The ILC Parameters Ctte • Rolf Heuer, Chair; Paul Grannis, Sachio Komamiya, Mark Oreglia, Francois Richard, Dongchul Son • Charge: The Parameters Subcommittee has been set up by the ILCSC and will report to it, the first report being expected at the meeting in August during the 2003 Lepton Photon Conference. The group comprises two members each from Asia, Europe and North America. It shall produce a set of parameters for the future Linear Collider and their corresponding values neededto achieve the anticipated physics program. This list and the values have to be specific enough to form the basis of an eventual cost estimate and a design for the collider and to serve as a standard of comparison in the technology recommendation process. The parameters should be derived on the basis of the world consensus document “Understanding Matter, Energy, Space and Time: The case for the e+e- Linear Collider” using additional input from the regional studies. The final report will be forwarded to the ILCSC for its acceptance or modification by mm/yyyy (month and year). The parameter set should describe the desired baseline (phase 1) collider as well as possible subsequent phases that introduce new options and/or upgrades. For all phases and options/upgrades priorities should be discussed wherever possible and appropriate, and the description should include at least the following parameters: • Operational energy range • Minimum top energy •Integrated luminosity and desired time spent to accumulate it, for selected energy values (e.g. at the top energy, at the Z-pole, at various energy thresholds…) •Polarisation and particle type for each beam • Number and type of interaction regions The committee may include any other parameter that it considers important for reaching the physics goals of a particular phase, or useful for the comparison of technologies, subject to the approval of the ILCSC. M. Oreglia

15. Our First Meeting Was Today • First thoughts on parameters • should be as specific as possible • We should not repeat physics justification where we can refer to world wide accepted documents or statements. • For all other cases we have to justify our choices. • Disclaimer: not appropriate to release all the details of our discussion • We will describe 3 categories: • Baseline: the initial 4-6 year program • Upgrade: the energy upgrade (a given!) • Options: running and modifications we might want to do • Schedule: next meeting at LP03; draft document a month later M. Oreglia

16. Baseline • This discussion converged quickly • top energy 500 GeV; polarized electrons • energy range for physics (i.e. high lumi running) 200-500 GeV • Questions • Discuss Z, WW scan as baseline? • Probably will be an option. • Linked to positron polarization, energy resolution • specify ∫Ldt at 500 GeV equivalent? • how to treat commissioning time? • specify ∫dt and/or L? Justification ? • 4 years to get 500 fb-1; another 500 in next 2 years • E scan capability and requirements • Number of interaction regions, number of detectors ??? • Statement of crossing angle tradeoffs and need for more study • Running at higher E at reduced luminosity … part of baseline? • Z calibration…statement about changeover time • Open question: statement about energy spread??? M. Oreglia

17. The Energy Upgrade • It is inconceivable we would not want to run at maximum energy, so this upgrade is a given in the timeline • The big question: what energy to state? • Vicinity of 1 TeV? At least 800 GeV??? • Conservative integrated lumi specified over 3 year period • Capability to do E scans • Capability to go back down to lower energy at good luminosity M. Oreglia

18. Options • Positron polarization • Minimum level (60%?) • State maximum tolerable lumi loss • For all energies • Case for Transverse polarization • GigaZ; WW scan • State conditions for useful running • Positron polarization • Beam energy resolution • Physics need • gg/eg/e-e- • all energies above 200 GeV M. Oreglia

19. Timeline • We want to proceed swiftly on this • Few controversies • Aiming for draft document by late August • We should be in good shape during LP03 • What happens next? • Comments solicited from WG leaders and regional Steering Groups • ILCSC decides how to implement the document M. Oreglia