Ecal Simulation Report Brian Heltsley Simulation Mtg 07 June 2010

1. Ecal Simulation Report Brian Heltsley Simulation Mtg 07 June 2010 B. Heltsley Simulation Mtg - 07 Jun 2010

2. Recent Release Activity • Bugs 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 2010

3. Ecal Alignment News • ES Alignment studied B. Heltsley Simulation Mtg - 07 Jun 2010

4. More on alignment • Egamma 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 2010

5. Alignment validation • Tried 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 2010

6. Study of APD-MC Re-Digi B. Heltsley Simulation Mtg - 07 Jun 2010

7. Number B. Heltsley Simulation Mtg - 07 Jun 2010

8. Energy APD energies probably a bit too high B. Heltsley Simulation Mtg - 07 Jun 2010

9. E4/E1 Too many spikes! B. Heltsley Simulation Mtg - 07 Jun 2010

10. Timing B. Heltsley Simulation Mtg - 07 Jun 2010

11. 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 2010

12. 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 2010

13. 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 2010

14. Backup slides B. Heltsley Simulation Mtg - 07 Jun 2010

15. APD Simulation • 3rd 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 Digitization • Tag 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? The Real Thing • DPG has not yet addressed this to my knowledge B. Heltsley Simulation Mtg - 07 Jun 2010

16. 3_7_0_pre3 APD Layout 3G (vertical not to scale) Capsule Crystal Ceramic The Real Thing Bulk Si Lo-gain active Si 1.65 mm Hi-gain active Si Non-depeleted Si 400 m 45 m 5 m 5mm Epoxy 0.1 m 575m Silicone Glue 30 m Crystal B. Heltsley Simulation Mtg - 07 Jun 2010

17. Digitization parameters • SimCalorimetry/EcalSimProducers/python/ apdSimParameters_cff.py • apdAddToBarrel = 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 2010

18. The Physical APD • Issues include: • What are relevant interactions? • Thermal neutrons? K0L ? e- ? • Can GEANT simulate any of this? • Thin layers • Special physics lists? • S. Banerjee investigating The Real Thing B. Heltsley Simulation Mtg - 07 Jun 2010