B. Heltsley Simulation Mtg - 07 Jun 20101

Ecal

Simulation

ReportBrian Heltsley

Simulation Mtg 07 June 2010

Recent Release ActivityBugs in APD digitization described last time fixed & published in 38X

Correctly redigitized MinBias-with-APD MC sample examined more closely

Ecal Alignment for Reco to be activated

B. Heltsley Simulation Mtg - 07 Jun 20102

Ecal Alignment NewsES Alignment studied

B. Heltsley Simulation Mtg - 07 Jun 20103

More on alignmentEgamma group noticed EE misalignment & reduced efficiency for endcap electrons

ES studies indicate relative EE-ES alignment is near-ideal

Egamma studies show similar-sized offsets

We decided to ‘turn on’ Ecal alignment

B. Heltsley Simulation Mtg - 07 Jun 20104

Alignment validationTried feeding in fake <1cm misalignments for EB, EE, ES via a TestProducer– Ran standard geometry self-consistency diagnostics. Oops!

• All three Ecal geometry classes had some built-in assumptions of perfect geometry

– These codes >5 years old

• getClosestCell( GlobalPoint& ) broken!• getCells( GlobalPoint&, double ) broken!

• Finally finished fixing these last week

• Changes published for 38X

DB Payloads with ES, EE alignments created– Being tested in a re-Reco by Egamma, ES groups

Also zero-alignment payload for MC Reco

B. Heltsley Simulation Mtg - 07 Jun 20105

Study of APD-MC Re-Digi

B. Heltsley Simulation Mtg - 07 Jun 20106

Number

B. Heltsley Simulation Mtg - 07 Jun 20107

Energy

B. Heltsley Simulation Mtg - 07 Jun 20108

APD energies probably a bit too high

E4/E1

B. Heltsley Simulation Mtg - 07 Jun 20109

Too many spikes!

Timing

B. Heltsley Simulation Mtg - 07 Jun 201010

APD Simulation Conclusions

Many qualitative features of the data which were previously completely missing from simulation are now surprisingly well-modeled

Need to move APD pulse back by 4-5 ns – Happens at digitization (parameter)

Probably need to reduce APD energy factors (~20%?) to retune spectrum & number

That MC sample did not have latest geometry with increased epoxy thickness– Iterate once more with 38X?

Planning for making APD geometry the default in 38X (any reason not to?)

B. Heltsley Simulation Mtg - 07 Jun 201011

Other Sim changes in progress(unchanged since last time)

Test containment factor– Sets overall MC energy normalization for EB & EE separately by

looking at simulated single 50 GeV photons– Not sure if GEANT has changed since this was updated

Change from fixed, uniform single-sample ADC noise to measured channel-by-channel values? – Can test with only a cfg change. Who/when ?

Correlation matrix for ES (which has 3 time samples)– Ming & I are examining this– Would be much more efficient than current CPU & memory-

intensive so-called “fast” method which tries to account for some of the correlations (ironically, with slower code)

B. Heltsley Simulation Mtg - 07 Jun 201012

Simulation Housekeeping(Unchanged since last time)

In progress– Reform digitized hit response handline

• Has same problem as analog version, too many new ‘s & delete’s

– Add ES digi creation to EB/EE templatized version, if possible– Inefficient ES Digi object (collection of std::vector<int> )

• Should look more like EB & EE Digi objects (long optimized)

• F. Ferri & P. Gras agree

• Migration would have to be carefully orchestrated

B. Heltsley Simulation Mtg - 07 Jun 201013

Backup slides

B. Heltsley Simulation Mtg - 07 Jun 201014

APD Simulation3rd generation geometry introduced– Input from Q. Ingram & I. Musienko

– Epoxy layer about twice as thick as in 2G APD geometry (which was 200 m)

– Further APD measurements could alter details

APD DigitizationTag set in 3_7_0_pre1 that allows it

Choose APD geometry w/1 or 2 layers

APD digitization either added to crystal digis &/or separately (as an “MC truth”), controllable via cfg.py parameter

APD layer-gains controllable via cfg.py

What test(s) & validation(s) are required to use as default?

B. Heltsley Simulation Mtg - 07 Jun 201015

The Real Thing

DPG has not yet addressed this to my knowledge

APD Layout 3G (vertical not to scale)

B. Heltsley Simulation Mtg - 07 Jun 201016

CrystalSilicone GlueEpoxy

Non-depeleted SiHi-gain active Si

Lo-gain active Si

Bulk SiCeramic

Capsule

1.65 mm

30 m

575m0.1 m

5 m45 m 400 m

Crystal

5mm

3_7_0_pre3

The Real Thing

Digitization parametersSimCalorimetry/EcalSimProducers/python/

apdSimParameters_cff.pyapdAddToBarrel = cms.bool(False), apdSeparateDigi = cms.bool(False), apdSimToPELow = cms.double(4.41e6), apdSimToPEHigh = cms.double(157.5e6), apdTimeOffset = cms.double(-10.0), apdDoPEStats = cms.bool(True), apdDigiTag = cms.string("APD"), apdShapeTstart = cms.double( 74.5 ), apdShapeTau = cms.double( 40.5 )

Shape: S(t) = A(t) ( 1 – exp[A(t)] ) where A(t) = (t – tS)/

B. Heltsley Simulation Mtg - 07 Jun 201017

The Physical APD

B. Heltsley Simulation Mtg - 07 Jun 201018

The Real Thing

Issues include:What are relevant interactions?

Thermal neutrons? K0L ? e- ?

Can GEANT simulate any of this?Thin layersSpecial physics lists?S. Banerjee investigating