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Experimental Issues

Experimental Issues. Ray Frey University of Oregon ICLC Paris, April 19, 2004. Physics imperatives detector implications The LC environment & implications interaction region initial state(s) accelerator technology Revisiting detector design issues major parameters

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Experimental Issues

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  1. Experimental Issues Ray Frey University of Oregon ICLC Paris, April 19, 2004 • Physics imperatives • detector implications • The LC environment & implications • interaction region • initial state(s) • accelerator technology • Revisiting detector design issues • major parameters • Session Thursday • implications • technology choices: H. Yamamoto • Issues for the workshop ICLC, Paris R. Frey

  2. Timeline for Experimentalists • Transfer of physicist-days from physics studies to detector R&D • Essential, since we are pushing frontiers in several areas • Good: Experimental issues being addressed in more detail • This talk • Bad: Many physics studies need (much) more work J. Yu, Jan 2004 ICLC, Paris R. Frey

  3. Physics Imperatives #1 A light Higgs boson • SM, from precision EW • SUSY • Measure its properties • Mass • Width • Spin • Branching fractions • Couplings to gauge bosons • Self-couplings • Top Yukawa coupling • Go after additional family members • Ho, H (2HDMs, etc) • CP violation ( collider) ICLC, Paris R. Frey

  4. Physics Imperatives (contd) #1 A light Higgs boson (contd) • The higgstrahlung process: e+e ─ → Zh • Isolate Higgs sample independent of its decay modes • Momentum resolution drives tracker design: p/p2≈ few x 10-5 GeV-1 TESLA TDR SiD ICLC, Paris R. Frey

  5. Physics Imperatives (contd) #1 A light Higgs boson (contd) • Measure its properties • Mass  • Width  • Spin  • Branching fractions  • Drives vertex det designs • Couplings to gauge bosons  • Self-couplings • Top Yukawa coupling TESLA TDR Challenging! Important! Few x 10% sensitivity … in general need more experimental scrutiny ICLC, Paris R. Frey

  6. Physics Imperatives, contd. e+e ─ → (sμ)(sμ)→μμ #2 Light SUSY ? • Shows off LC capabilities • Good example of LHC/LC complementarity GLC project report TESLA TDR However….

  7. Physics Imperatives, contd. Possible experimentalist solution to the hierarchy problem… • TONOTA (theory of none-of-the-above) • Open-mindedness reinforced by recent theoretical creativity… • MSM • MSSM • Fat Higgs • Little Higgs • SUSY t-color models • Higgs-less (extra dims.) • Topcolor • TONOTA H. Murayama ICLC, Paris R. Frey

  8. Physics Imperatives, contd. #2 Well… um… hmmm My view (still): This is a facility of exploration, not specialization. • Must be ready for anything many possibilities ! • However, we expect final states which include: • Multi-jet final states • With or without beam constraint • Leptons • including tau • Heavy quarks • Missing energy/mass • Combinations of these TESLA TDR ICLC, Paris R. Frey

  9. Physics Imperatives, contd. Be prepared to exploit the inherent power of LC • Well-defined initial state • Energy, tunable • Momentum constraints • No gluons • Quantum numbers • Polarization: e─ , e+,  • Possibilities for  , e─ ,e─ e─ • Tiny collision region • Ability to reconstruct hadronic final states • Ability to tag heavy (light) quarks • Excellent missing energy/mass sensitivity • Ability to choose energy, polarization of collisions • Threshold scans, Giga-Z • Modulation of signals and backgrounds IR, Large ICLC, Paris R. Frey

  10. A typical physics roadmap GLC Project report Sensible programs can be formulated to cover all of the (foreseen) physics within a luminosity and energy budget. e.g. P. Grannis hep-ex/0211002 (LCWS2002)

  11. “At the LC, the initial state is well defined”… A Luminosity Spectrum dL/dE • Contributions • ISR • Beamstrahlung • Linac energy spread, E/E • Measuring dL/dE  “(Eo) + tail”  Broadening near Eo ICLC, Paris R. Frey

  12. Mean beam-energy measurement SLC extraction line spectrometer E = (cL/d)  Bdl ~few x10-4 but… Not so straightforward at fLC Requires calibration/crosscheck of energy scale  M. Woods ICLC, Paris R. Frey

  13. Using detector final states • Bhabha acollinearity   (E+ – E─) sin /E • Sum? • Several possibilities • Z, ZZ, WW? • Promising: radiative returns ee─→ Z →      ICLC, Paris R. Frey

  14. energy constraints (contd) OPAL ALEPH

  15. energy constraints (contd) ee → Z →  (ff) • Systematics? • Precise positions/angles in forward tracking system • or invariant mass recon. In forward system •   few degrees for high energy running   ICLC, Paris R. Frey

  16. Energy spread effects on physics • ISR + beamstrahlung • ~Lum. loss at nominal √s • Provide radiative returns • Linac energy spread • Can smear out narrow structures ee─ → t t at threshold ICLC, Paris R. Frey

  17. LC Calorimetry (global really) LHC Study: Z→ 2 jets D. Green, Calor2002 • FSR is the biggest effect. • The underlying event is the second largest error (if cone R ~ 0.7). • Calorimeter resolution is a minor effect. σM / M  13% without FSR • At the LC, the situation is reversed: Detection dominates. • Opportunity at the LC to significantly improve measurement of jets. ICLC, Paris R. Frey

  18. calorimetry (contd) Complementarity with LHC: LC should strive to do physics with all final states. • Charged particles in jets more precisely measured in tracker • Jet energy 64% charged (typ.) Separate charged/neutrals in calor.  The “Particle Flow” paradigm • ECAL: dense, highly segmented • HCAL: good pattern recognition H. Videau ICLC, Paris R. Frey

  19. Energy Flow Algorithms Dean Karlen, LCWS 2002 • Ignoring the (typically) negligible tracking term: • is the largest term of all ICLC, Paris R. Frey

  20. calorimetry (contd) Expectations for jet resolution • Let σ(confusion)=0 (QCD+res) • What can we expect for σ(conf) ? • Requires full simulations with believable MC (Geant4?) • To be verified at test beams • Development of algorithms • Studies to date: jet res  0.3/  Ejet TESLA TDR Z→ 2 jets •Z peak •ZH 500GeV Hope to see more PFA results Brient, Jeju LCWS ICLC, Paris R. Frey

  21. calorimetry (contd) Brient, Calor2004 • Such a calorimeter will also do very well for: • Photons, including non-pointing • Electrons and muons • Tau id. and polarization • 3rd generation • Yukawa coupling • Separation of tau final states →→+o H. Videau ICLC, Paris R. Frey

  22. Hermiticity • This is a 4π issue, of course • We focus on the forward region, which has been “under appreciated”. TESLA ICLC, Paris R. Frey

  23. hermiticity (contd) • Consider as an example: sleptons nearly mass-degenerate with neutralinos • Favored by SUSY-WIMP consistency with CDM • The SUSY events will look like 2-photon events… unless the 2-photon electron is vetoed. • Requires good forward veto coverage e+ e- smu+ smu- e+ e- e+ e-m+m- OPAL G. Wilson ICLC, Paris R. Frey

  24. hermiticity (contd) Veto < 25 mrad ? (Msmu-MLSP)/Msmu= 2.8%,5.6%,11% T. Maruyama G. Wilson ← pairs 2-photon bkgd Veto to 25 mrad No veto ← 250 GeV e- • requires few ns readout (warm) • TESLA: veto to 6 mrad (Lohmann)

  25. At the LC, vertexing is (nearly) ideal • Tiny, stable interaction point • Small inner radius 1 cm • Clean events allow full reconstruction of secondary vertices  mass, charge, … • Beam duty cycle allows readout of even slow pixel detectors • Pixels provide pileup immunity • Moderate radiation • Superior b,c (u,d) flavor tagging, tau’s ICLC, Paris R. Frey

  26. Accelerator Technology Warm or Cold ?? Yes, please ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! • Implications on detector design • (my opinion: small effects ) • energy spread • bunch timing structure • crossing angle ICLC, Paris R. Frey

  27. Lum-wted ECM Linac beam energy spread = E/E, one beam, X-band E E ─ Warm:  ≈ 0.3 % Cold:  ≈ 0.1 % ICLC, Paris R. Frey

  28. Linac energy spread ee─ → Zh T. Barklow • Warm: ~0.3% • Cold: ~0.1% • Additional examples in Machine-detector interface sessions warm warm cold cold ICLC, Paris R. Frey

  29. Beam crossing time structure Warm • Fast readouts: OK, no pileup • Digital pipeline • bx live: 5 10-3 Cold • Pileup over bunch train • Or fast timing • bx live: 3 10-5 •  power pulse ICLC, Paris R. Frey

  30. Timing is good Warm detector concern: Pileup of → hadrons over bx train T. Barklow Si/W ECal Timing  1 ns 192 bx pileup (56 Hadronic Events/Train) 3 bx pileup (5ns) ICLC, Paris R. Frey

  31. Beam crossing angle • Warm machine: required (1.4 ns bx) • 20 mrad • Cold machine: optional • Advantage: comfortable beam diagnostics (energy, polarization measurements) • Disadvantage: small acceptance loss near beam line (1 cm) • the degenerate SUSY example • not easy to cover this, in any case • Note: The Dugan committee used crossing angles for both warm and cold SiD

  32. summary of design issues discussed Technology choices: next talk • Vertex detector • Inner radius • (material, readout speed) • Central tracker • Momentum resolution • Efficiency: jets, decays,etc • Forward tracking • Calorimeter • Segmentation • Timing • Hermiticity • Muon det • Large or Small ? ICLC, Paris R. Frey

  33. collimator Vertex detector inner radius In favor of a larger radius • Backgrounds • Pairs, photons, tracks (2-photon) • More comfortable extraction • Collimation wakefields  Lum reduction cold ≈ warm A. Seryi

  34. Vertex detector inner radius (contd) In favor of a smaller radius • Physics sensitivity A. Chou ZH, H→ cc • significant improvement ? • more studies? ICLC, Paris R. Frey

  35. Large or small detector ? The pairs background and the VXD inner radius  minimum B A naïve approach T. Maruyama Coil: B2R2L < c2 Particle flow: BR2 > c1 ICLC, Paris R. Frey

  36. S or L ? (contd) Cost BR2 R p/p Pattern recognition Backgrounds immunity ?? ?? S L • Warm vs. cold has technology correlations, not much (any?) for S vs L. • Look forward to session on Thursday ICLC, Paris R. Frey

  37. Summary • Goal: Push the envelope on measurement capabilities by exploiting the assets of the LC. • LC a discovery facility – let’s design our experimental program accordingly. • Need to continue simulation efforts while we ramp up for an interesting period of detector R&D. • Interplay of warm/cold and large/small issues has been healthy – has brought forward new issues… hopefully more this week! • Apologies to those whose work was not mentioned !! ICLC, Paris R. Frey

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