Calorimetry Summary
Dhiman Chakraborty, NIU
Linear Collider Workshop
UC Santa Cruz, 29-june-2002
The calorimetry WG of ALCPG



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/


To join, contact WG leaders (see above url).
Mailing list (listserv): lcd-cal@fnal.gov
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
2
Goals for this meeting




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,…
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
3
A few statistics …





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.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
4
Results of this meeting






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.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
5
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.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
6
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
7
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),
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
8
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.

29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
9
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 >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.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
10
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?
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
11
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?
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
12
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?
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
13
ECal technology choices:
1. Si-W (Breidenbach for SLAC+Oregon)





Proven technology, ample expertise.
Superb 3D segmentation, resolution.
Perfect for energy flow algorithms.
Too expensive?
Some electro-mechanical challenges are
new.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
14
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?
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
15
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.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
16
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 R&D.
Most of all, we need your participation.
29 June 2002
LC calorimetry summary, UCSC
Dhiman Chakraborty
17