The LC Machine Scope Documents:

1

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

• This will be a very brief report on the various
  scope activities
• US Scope paper
• European Scope draft
• International Parameters Committee very recent
  progress!

2
Braus 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 cttes
• 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

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_rep
  ort.html

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 Intl LC
• (http//blueox.uoregon.edu/lc/scope.ps)

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

6
Initial Energy and Luminosity

• Initial Energy 200-500 GeV at 21034 cm-2s-1
• ... actually, we also state this in integrated
  lumi
• Higgs
• Precision EW Higgs range mh115-200 GeV
• peak s 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???

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 gt 1 TeV upgrades
• Perhaps energy luminosity tradeoff is the
  answer here

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

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?
• Cant 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!

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

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 ee- 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

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
  ee- 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 ee- 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
• ??, e? laser facility with Lumi(??) Lumi(ee-)/2

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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 RD activities and make
  recommendations on the
• coordination and sharing of RD 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.

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 needed to 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 ee- 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.

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

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 calibrationstatement about changeover time
• Open question statement about energy spread???

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

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

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