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Reconstruction Issues for Silicon/Tungsten ECal

Reconstruction Issues for Silicon/Tungsten ECal. R. Frey U. Oregon NIU Workshop, Nov 8, 2002. Outline. ECal Physics Goals Current implementations SD TESLA The hardware constraints Resolution requirements

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Reconstruction Issues for Silicon/Tungsten ECal

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  1. Reconstruction Issues for Silicon/Tungsten ECal R. Frey U. Oregon NIU Workshop, Nov 8, 2002 NIU Workshop R. Frey

  2. Outline • ECal Physics Goals • Current implementations • SD • TESLA • The hardware constraints • Resolution requirements • What simulation studies do the detector prototypers (we) want the simulators (us) to do -- discussion NIU Workshop R. Frey

  3. ECal Goals • Photons in Jets • Id. with high efficiency and measure with reasonable E resolution • … in a very busy environment. Demand eff>95% with high purity • Photon shower imaging •  vertexing (impact param. resolution 1 cm) • º→ • Separation from nearby photons, MIPs, h-shower fragments • MIP tracking (h , muons) • Id. Hadrons which shower in ECal • Reconstruction of taus (eg →→º→--mip) • b/c reconstruction – include neutrals in MQ estimate • e’s and Bhabhas (Lum. spectrum) – easy (readout dynamic range) • Backgrounds immunity • Segmentation • Timing NIU Workshop R. Frey

  4. SD Si/W • 5x5 mm2 pixel 50M pixels • For each (6 inch) wafer: • 1000 pixels (approx) • One readout chip (ROC) • Simple, scalable detector design: • Minimum of fab. steps • Use largest available wafers • Detector cost below $2/cm2 • Electronics cost even less • A reasonable (cheap?) cost M. Breidenbach, D. Freytag, G. Haller, M. Huffer, J.J Russell Stanford Linear Accelerator Center R. Frey, D. Strom U. Oregon V. Radeka Brookhaven National Lab

  5. Readout chip connections Use bump-bonding technique to mate ROC to array of pads on wafer

  6. CALICE design with electronics inside detector AC coupling elements ? Thermal contact Aluminium 1.3 mm Cooling tube Cooling tube VFE chip powerline command line signal out 1.0 mm PCB Pad 0.5 mm Silicon wafer Gluing for electrical contact

  7. Si Timing • Dynamic range: MIPs to Bhabhas • About factor 2000 range per pixel • Want to maintain resolution at both ends of scale • Timing: What do we need? • NLC: 200 ns bunch trains – Do we need to resolve cal. hits within a bunch? • Bhabhas: 15 Hz for >60 mrad at 1034 • What about 2-photon/non-HEP background overlays? • Exotic new physics signatures  Can try to provide timing for each pixel Is ≈10 ns resolution sufficient ? NIU Workshop R. Frey

  8. What are the constraints from the hardware? • Dynamic range OK • Transverse segmentation almost independent of cost within reasonable range (watch thermal load) • Segmentation < Moliere radius is OK • Radiation damage probably non-issue • Timing perhaps possible with resolution of 10-20 ns • Moliere radius (9mm x 2) • Energy resolution ↔ long. sampling ↔ Money • More coarse with ECal depth • Also: pattern recognition implications NIU Workshop R. Frey

  9. e+e-→jj, 200 GeV; LCDRoot FastMC • Perfect pattern recog. • 0.01/sqrt(E)  0.01 (EM) • 0.01/sqrt(E)  0.01 (HAD) • 0.10/sqrt(Ej) • 0.11/sqrt(Mjj) NIU Workshop R. Frey

  10. HAD: 0.50/sqrt(E)  0.02 0.18/sqrt(Ej) EM: 0.12/sqrt(E)  0.01 HAD: 0.70/sqrt(E)  0.02 EM: 0.20/sqrt(E)  0.01 0.20/sqrt(Ej) 0.19/sqrt(Ej) NIU Workshop R. Frey

  11. E Eh0 E > 0.5 GeV 0.19/sqrt(Ej) E > 1 GeV, Eh0 >1 GeV 0.20/sqrt(Ej) E > 2 GeV 0.20/sqrt(Ej)

  12. What simulations studies do we need? • EFA tuning ↔ segmentation • -MIP separation •  , tau, pi-zero reconstruction • Background overlays ↔ timing requirement • Longitudinal sampling • EGS4 • Geant4 • Distribution of hit occupancy in a detector wafer NIU Workshop R. Frey

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