Calorimetry Summary

1. Calorimetry Summary Dhiman Chakraborty, NIU Linear Collider Workshop UC Santa Cruz, 29-june-2002

2. 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 LC calorimetry summary, UCSC Dhiman Chakraborty

3. 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,… LC calorimetry summary, UCSC Dhiman Chakraborty

4. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

5. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

6. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

7. LC calorimetry summary, UCSC Dhiman Chakraborty

8. 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), LC calorimetry summary, UCSC Dhiman Chakraborty

9. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

10. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

11. 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? LC calorimetry summary, UCSC Dhiman Chakraborty

12. 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? LC calorimetry summary, UCSC Dhiman Chakraborty

13. 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? LC calorimetry summary, UCSC Dhiman Chakraborty

14. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

15. 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? LC calorimetry summary, UCSC Dhiman Chakraborty

16. 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. LC calorimetry summary, UCSC Dhiman Chakraborty

17. 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. LC calorimetry summary, UCSC Dhiman Chakraborty