Transcript Document

Calorimetry Summary
Dhiman Chakraborty, NIU
Linear Collider Workshop
UC Santa Cruz, 29-june-2002
The calorimetry WG of ALCPG
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Coordinates R&D between univ/lab research
groups, funding agencies, consortia.
A forum for discussion and sharing results.
Meets biweekly – mon, 3:30-5:00 pm, CST.
Video/phone conferencing available.
Status, plans, docs, meeting info, archives …
www.slac.stanford.edu/xorg/lcd/calorimeter/
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To join, contact WG leaders (see above url).
Mailing list (listserv): [email protected]
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LC calorimetry summary, UCSC
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Goals for this meeting
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Learn from experts about important issues,
past experience, guiding principles.
Progress reports, plans from groups that have
started R&D 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 …
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5-hr session (stretched from 3) yesterday.
17 talks (from 17 speakers).
At least as many more listeners (who didn’t
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
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A list of R&D 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 R&D 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 (Turcot)
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Need unprecedented energy and direction resolution
for jets, photons, invisibles.
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~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
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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. Don’t 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
(<~0.15 E) to be measured by the HCal.
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Energy flow algorithms
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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 >30M cal channels.
Accurate cell-by-cell energy measurement may
be less important : save cost by reducing
dynamic range – “digital HCal”?
dE/E<0.3E/sqrt(E) may be achievable.
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HCal technology choices:
1. Scintillators (Zutshi for NIU)
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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)
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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)
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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 SLAC+Oregon)
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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)
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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
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Joint undertaking between SLAC, NIU
others. Much in progress
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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
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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 R&D.
Most of all, we need your participation.
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