Optimization of the Design of the Forward Calorimeters ECFA LC Workshop Montpellier, 15 November 2003 *FC Collaboration: Colorado, Cracow, DESY(Zeuthen),

Optimization of the Design of the Forward Calorimeters

ECFA LC WorkshopMontpellier, 15 November 2003

*FC Collaboration:

Colorado, Cracow, DESY(Zeuthen), JINR Dubna, London (UC), Minsk (BSU), Prague, Protvino (IHEP), Tel Aviv Collaboration

Agnieszka Kowal * University of Science and Technology, Cracow

Agnieszka Kowal ECFA 2003, Montpellier

2

Agenda

• Layout and functions of the forward calorimeters• Optimization of LAT design and angle

reconstruction algorithms• Stripped LAT design as an alternative• Laser alignment system for LAT• Performance of LCAL with real beam simulation


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Forward Calorimeter Layout

• LAT– z = 305-325 cm– R= 8-28 cm – 26.2<<82 mrad– 0<<360 deg

• LCAL– z = 365-385 cm– R = 1.2-8 cm – 5<<28 mrad – 0<<360 deg

TDR design (postponed)

New mask design


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Functions of the very forward calorimeters

• Measurement of luminosity (LAT)

• Fast beam diagnostics (LCAL)

• Detection of electrons and photons at very small angles

• Shielding of the tracking detectors


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• Si/W calorimeters on both sides of the IP

• 8-128 concentric cylinders (in r)• 30 rings (in z)• 24/48 sectors (in )• Detector simulation with

Barbie–Geant3.21 (L.Suszycki)• Single 250 GeV electrons

LAT Design Simulation

beam pipe

Tungsten mask


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LAT – reconstruction and resolution

24 sectors 48 sectors

Resolution as function of the number of cylinders

readout from odd rings onlyreduction of the # of channels

Angle reconstruction with simple energy weighting


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LAT – reconstruction and resolution

48 sectors24 sectors

Resolution as function of the number of cylinders

resolution better for 48 sectors

Optimum LAT segmentation: 32 cylinders in R 48 sectors in 30 rings in z (readout from every 2nd)

23040 channels

artificial shift


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LAT – performance with energy

E=40%√E

Ebeam = 62.32 * Edet + 0.36

0.2E-03

0.035

()

()

Energy Resolution & Calibration Angular Resolution vs Energy

R. Ingbir (TAU)


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LAT – angle reconstruction methods

i

ii

E

EXX

i

ii

W

WXX

)]}ln([,0max{T

ii E

EconstW

Rec - Gen (rad) Rec - Gen(deg) Mean 0.2961E-03

Sigma 0.5809E-03

Mean –0.2361

Sigma 3.240

Mean 0.0975E-04

Sigma 0.2167E-03

Mean –0.7009

Sigma 1.917

i

ii

E

EXX

i

ii

W

WXX

)]}ln([,0max{T

ii E

EconstW

Rec - Gen (rad) Rec - Gen (rad) Rec - Gen(deg) Rec - Gen(deg) Mean 0.2961E-03

Sigma 0.5809E-03

Mean –0.2361

Sigma 3.240

Mean 0.0975E-04

Sigma 0.2167E-03

Mean –0.7009

Sigma 1.917

15 cylinders / 24sectors / 30 rings Bhabha scattering with BHWIDE

Simple weighting

Logarythmic weighting

R. Ingbir (TAU)250 GeV


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LAT – design optimization

• # of active rings around the shower maximum

• logarythmic weighting in angle reconstruction

() ~ 70 rad feasible

resolution as function of the depth

# of cylinders

R. Ingbir (TAU)


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LAT – Stripped design

• 30 tungsten rings• every second ring has either

120 radial or 64 concentric Si strips

• 2960 readout channels

B.Pawlik (INP-PAN, Cracow)


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Stripped LAT reconstruction results

• Accuracy in measuring

is 0.5x10-4 rad• Energy measurement

with accuracy of

5 GeV (E~0.31√E)• low segmentation level

seems to be sufficient (~3000 read-out chan.)

B.Pawlik (INP-PAN, Cracow)


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Laser measurement of the LAT detector displacement

reconstruction of He-Ne laser spot on CCD camera

Requirements on alignment:Inner Radius of LAT < 4 μmAxial LAT position < 60 μm

possible resolution of ~1m if the center of the light spot is determined with accuracy better than 0.1 pixel

J.Zachorowski (UJ),W.Wierba (INP-PAN) Cracow

work has just started


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LCAL performance with Real Beam simulation

Included in the simulation:

ground motion, feedback system delay,

emittance growth,lumi optimisation

V.Drugakov (BSU, Minsk)


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Real Beam vs. Ideal Beam LCAL particle recognition performance

• the identification efficiency of electrons close to the beam is nearly the same for RB and IB

• fake rate resulting from BG fluctuation is on the same level

100 GeV

V.Drugakov (BSU, Minsk)


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Summary

• optimization of LAT structure and angle reconstruction algorithms is ongoing

(so far () ~ 70rad achieved)• room for improvement in angular reconstruction

algorithms (reduction of the bias in )• LAT sensor geometry (pad/strip) is still discussed • for the goal L/L precision a laser alignment

system is being developed for LAT• LCAL registration efficiency good for electrons

with energy above 100 GeV

Documents

Optimization of the Design of the Forward Calorimeters ECFA LC Workshop Montpellier, 15 November 2003 *FC Collaboration: Colorado, Cracow, DESY(Zeuthen),