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

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty2 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 … To join, contact WG leaders (see above url). Mailing list (listserv): The calorimetry WG of ALCPG

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty3 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 Chakraborty4 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 Chakraborty5 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 Chakraborty6 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 Chakraborty7

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty8 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 cm 2 (ECal), 1-10 (25?) cm 2 (HCal), Design constraints

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty9 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 Chakraborty10 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. Energy flow algorithms

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty11 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 Chakraborty12 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 Chakraborty13 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 Chakraborty14 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 Chakraborty15 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? ECal technology choices: 2. Crystal (Zhu for Caltech)

29 June 2002 LC calorimetry summary, UCSC Dhiman Chakraborty16 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 Chakraborty17 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. Summary