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ECAL Studies for the CLIC_ILD detector

Jacopo Nardulli, CERN LCD

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Why the ECAL is as it is ?• The LOI ILD Ecal structuring comes from an optimization from H.

Videau available here ECAL Optimization from H. Videau

• A few scenarios with different nr of layers and different absorber thickness are considered

• Similar studies have also been done by M.S.Amjad and have been presented at the CALICE Meeting in Casablanca

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Goal of this study

• Attempt a similar optimization on the CLIC version of the ILD detector

• To have an ECAL with less layers, therefore cheaper, but without degradation of the performance

• From our vol 2 CDR, cost chapter

• You see ECAL contribution (~30% ?)

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Two possible studies

•Fix the radiation length • But decrease the Nr of ECAL layers

• Less expensive, energy resolution can be worse, as the pattern recognition

• How to ?• Varying nr of layers and absorber thickness, • not the Si thickness

•Vary the radiation length • And decrease the Nr of ECAL layers

• Less expensive, overall performance changes• If I change the X0, can have more leakage into the HCAL • Varying nr of layers, absorber thickness and studying performance as a

function of the X0

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Now only first study: Different ECAL models

• Altering the number of layers and their absorber thickness in such a way that Total Absorber thickness in the detector remains the same.

• The analyses in this talk are done with PandoraPFA with• Single Photon with θ and φ varying in the full range and

Energies of 1, 10, 100 and 500 GeV and using• With Z uds events of 91, 200, 500 and 1000 GeV

• Default model 20 layers in 1st stack and 9 layers in 2nd stack

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Results for single photons

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Results: changing Nr of layers in 1st stack

Mean Rec. Energy vs Input EnergyMean Rec. Energy vs Input Energy

Energy Res. vs Input EnergyEnergy Res. vs Input Energy

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Results: changing Nr of layers in 2nd stack

Energy Res. vs Input EnergyEnergy Res. vs Input Energy

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Results: changing Nr of layers in 1st and 2nd stack

Energy Res. vs Input EnergyEnergy Res. vs Input Energy

Preliminary conclusion:Preliminary conclusion:Can go from 29 layers to 25 with hardly any loss in performanceCan go from 29 layers to 25 with hardly any loss in performance

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Results: just 1 stack

Preliminary resultsPreliminary resultsUsing just 1 stack with less, but thicker, layers does not seem to Using just 1 stack with less, but thicker, layers does not seem to degrade the energy resolution dramatically.degrade the energy resolution dramatically.

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Results for Z uds events

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Results: changing Nr of layers in 1st stack

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Results: changing Nr of layers in 2nd stack

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Results: changing Nr of layers in 1st and 2nd stack

Energy Res. vs Input EnergyEnergy Res. vs Input Energy

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Results: just 1 stack

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Conclusions First attempt of an optimization of the ECAL for CLIC_ILDFirst attempt of an optimization of the ECAL for CLIC_ILD

First results show that we can go from 29 to 25 layers with a small First results show that we can go from 29 to 25 layers with a small loss in performanceloss in performance

Using just 1 stack with less, but thicker, layers does not seem to Using just 1 stack with less, but thicker, layers does not seem to degrade the energy resolution dramatically.degrade the energy resolution dramatically.

Results described in LCD-Open 2011-004 document, available hereResults described in LCD-Open 2011-004 document, available here

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Next steps

Preliminary studies, lots of things not considered Preliminary studies, lots of things not considered i.e. is it right to use PFA ? Or should we use Garlic ?i.e. is it right to use PFA ? Or should we use Garlic ? Is the energy resolution the main/only parameter to be used Is the energy resolution the main/only parameter to be used

to understand possible loss of performance caused by having to understand possible loss of performance caused by having less layers ?less layers ?

Finish 1Finish 1stst study study More statisticsMore statistics Use RMS90Use RMS90

Move to the 2Move to the 2ndnd study study

Performance as a function of the X0Performance as a function of the X0

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Backup

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Results: changing nr layers in 2nd stack

Mean Rec. Energy vs Input EnergyMean Rec. Energy vs Input Energy

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Only 1 layer

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Results: changing Nr of layers in 1st and 2nd stack

Mean Rec. Energy vs Input EnergyMean Rec. Energy vs Input Energy

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Disclaimer• Here showing the Energy Resolution vs. the Energy and using

Single Gaussian fits

• To get the energy resolution I am NOT using the official MarlinProcessor which calculates rms90 and mean90

• So do not look at absolute numbers, but at the general trend of the plots

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Results: changing Nr of layers in 1st and 2nd

stack and different ratios

Reducing the X0 in 1Reducing the X0 in 1stst stack and changing the ratio does not stack and changing the ratio does not seem to help.seem to help.

Now try something elseNow try something else

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Thickness of layers