NIU Workshop R. Frey 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

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

Pad

Silicon wafer

PCB

Aluminium

Cooling tube Cooling tubeVFE chip

1.3 mm

1.0 mm

0.5 mm

Thermal contact

Gluing for electrical contact

AC coupling elements ?

power line command line signal out

CALICE design with electronics inside detector

NIU Workshop R. Frey 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

Ramp

Threshold

Ref

Mux

12 bit ADC

Logic

8.3 ms

200 ns

High Gain

Low Gain

Shaper

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

EM: 0.12/sqrt(E) 0.01HAD: 0.50/sqrt(E) 0.02

0.18/sqrt(Ej)

0.19/sqrt(Ej)

EM: 0.20/sqrt(E) 0.01 HAD: 0.70/sqrt(E) 0.02

0.20/sqrt(Ej)

11

E > 0.5 GeV

0.19/sqrt(Ej)

E

Eh0

E > 1 GeV, Eh0 >1 GeV0.20/sqrt(Ej)

E > 2 GeV0.20/sqrt(Ej)

NIU Workshop R. Frey 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