Calorimetry Summary

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Calorimetry Summary

• Dhiman Chakraborty, NIU
• Linear Collider Workshop
• UC Santa Cruz, 29-june-2002

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The calorimetry WG of ALCPG

• Coordinates RD between univ/lab research groups,
  funding agencies, consortia.
• A forum for discussion and sharing results. Meets
  biweekly mon, 330-500 pm, CST. Video/phone
  conferencing available.
• Status, plans, docs, meeting info, archives
  www.slac.stanford.edu/xorg/lcd/calorimeter/
• To join, contact WG leaders (see above url).
• Mailing list (listserv) lcd-cal_at_fnal.gov

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Goals for this meeting

• Learn from experts about important issues, past
  experience, guiding principles.
• Progress reports, plans from groups that have
  started RD already.
• Expressions of interest from those planning to
  join soon.
• Lots of discussions exchange ideas about
  technologies, algorithms, funding requests,

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A few statistics

• 5-hr session (stretched from 3) yesterday.
• 17 talks (from 17 speakers).
• At least as many more listeners (who didnt give
  a talk).
• No one slept, no one got hurt, physically or
  emotionally, despite violent agreement on some
  issues.
• The level of participation is most encouraging.

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Results of this meeting

• A list of RD topics being covered has been
  prepared (soon on our web page).
• Includes groups involved, their contact summary,
  status/plans, funding requests etc.
• Each group will maintain its own web page.
• Also a prioritized list of all RD needed.
• Together, help new participants decide what they
  want to do, who to work with.
• Figuring out how to write proposals.

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Physics requirements (Tucot)

• Need unprecedented energy and direction
  resolution for jets, photons, invisibles.
• 30/sqrt(E) for jets to separate W Z.
• Precise and accurate missing energy resolution
  for SM as well as new physics.
• Must be able to find non-pointing photons a
  tell-tale signature of GMSB.
• New algorithms required to meet E resolution
  goal.
• Hermeticity crucial for missing energy
  measurement.

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Design constraints

• Min inner radius of barrel limited by tracking
  resolution requirement, 1.5 m.
• Max outer radius limited by budget and desire for
  5T B field in entire cal, 2.5 m.
• Similarly for length 3-5 m.
• Fineness of lateral and radial segmentation
  limited by budget, technical challenges 0.25
  cm2 (ECal), 1-10 (25?) cm2 (HCal),

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The Energy Flow Paradigm (Graf, Maciel, Bower)

• Hadron calorimeter has the poorest E resolution
  up to 100 GeV. Dont use it any more than you
  have to.
• Use precision tracker to measure momenta of all
  charged tracks in a hadronic jet
• (0.6 E), and ECal for photons (0.25 E).
• This leaves only long-lived neutral hadrons
  (lt0.15 E) to be measured by the HCal.

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Energy flow algorithms

• Must have the ability to separate charged
  clusters from neutrals.
• Requires a tracking calorimeter with fine 3D
  granularity many layers of cells of small
  lateral dimensions.
• The baseline SD design has gt30M cal channels.
• Accurate cell-by-cell energy measurement may be
  less important save cost by reducing dynamic
  range digital HCal?
• dE/Elt0.3E/sqrt(E) may be achievable.

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HCal technology choices 1. Scintillators
(Zutshi for NIU)

• Proven technology, ample experience.
• No fluids, HV, I, T-sensitivity in detector.
• Stable, robust.
• Flexible dynamic range.
• Tough challenge to route fibers without
  compromising hermeticity.
• Too expensive? How small is small enough for
  lateral segmentation?

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HCal technology choices 2. RPCs (Magill for ANL)

• Relatively inexpensive.
• On-board digitization eases readout.
• Initial tests w/ glass are encouraging good
  eff.
• HV required.
• Robustness, stability over time, noise?

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HCal technology choices 3. GEMs (White for UTA)

• Relatively inexpensive.
• On-board digitization eases readout.
• New technology, never tried for Cal.
• Robustness, stability over time, noise?

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ECal technology choices 1. Si-W (Breidenbach
for SLACOregon)

• Proven technology, ample expertise.
• Superb 3D segmentation, resolution.
• Perfect for energy flow algorithms.
• Too expensive?
• Some electro-mechanical challenges are new.

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ECal technology choices 2. Crystal (Zhu for
Caltech)

• Proven technology, ample expertise.
• Good energy and position resolution.
• Excellent hermeticity.
• Electro-machanically sound.
• Relatively inexpensive.
• Very limited longitudinal segmentation.
• Will it compromize E-flow?

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Simulation efforts

• Joint undertaking between SLAC, NIU others. Much
  in progress
• transition to GEANT4,
• more flexible geometries,
• prototype simulation,
• Parametrized fast detector simulation.
• Great need across the board.
• Exciting opportunities for everybody.

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Summary

• Many expressions of interest.
• Several efforts are already underway.
• Many more are imminent.
• Most, but not all high-priority tasks are
  receiving attention.
• Collaboration forming, smooth so far.
• Need funding for continuation of RD.
• Most of all, we need your participation.