1. Simulating SiD for the LOI Norman Graf (SLAC) SiD Phone Meeting July 30, 2008

2. 2 LOI Detector Simulations Need to clarify exactly what is required for the LOI and what is deferred to the CDR/TDR. To-date the philosophy has been to provide a very flexible framework which would allow a number of detectors to be designed and studied very quickly. Answer the “big picture” questions first where the details do not matter, then only spend time and effort to study the engineering details on a roughly optimal design.

3. 3 Detectors under investigation acme0605 acme0605_1cmecal acme0605_30layerecal acme0605_40layerecal acme0605_ecal150 acme0605_ecal150_4T acme0605_ecal150_steel_rpc acme0605_ecal150_steel_scint acme0605_ecal150_w_rpc acme0605_ecal175 acme0605_ecal175_3T acme0605_ecal175_4T acme0605_ecal175_steel_rpc acme0605_ecal175_steel_scint acme0605_ecal175_w_rpc acme0605_steel_rpc acme0605_steel_scint acme0605_w_rpc acme0703_cu_rpc acme0703_cu_scint acme0703_pb_rpc acme0703_pb_scint apex0705_r125_steel1.5_scint apex0705_r125_steel2.5_scint apex0705_r125_steel_scint apex0705_r125_steel_scint_3x3hcal apex0705_r125_w_scint apex0705_r150_steel_scint apex0705_r150_steel_scint_4T apex0705_r175_steel_scint apex0705_r175_steel_scint_3x3hcal apex0705_r175_steel_scint_4T apex0705_r175_steel_scint_4T_3x3hcal apex0705_r200_steel_scint apex0705_r200_steel_scint_4T apex0705_r225_steel_scint apex0705_r225_steel_scint_3x3hcal apex0705_r225_steel_scint_3T apex0705_r225_steel_scint_4T sid01 sid01_scint sid01_scint_3x3hcal sid01_polyhedra

4. 4 sid01 The current model of the Silicon Detector is, therefore, quite simple, consisting of cylindrical barrel geometries and disks in the forward region. A lot of effort has gone into ensuring that the correct amount and distribution of material is included, but there are no cracks, gaps or overlaps. The detector description can be found at: http://confluence.slac.stanford.edu/display/ilc/sid01

5. 5 Improved Simulations Having settled on a concept with the requisite performance, will have to design a detector which can be built. Engineering will have to be done to come up with the plans, but the existing simulation package can already handle arbitrarily complex shapes. Can then study effects of support material, dead regions due to stay-clears, readout, power supplies, etc. However, hard work is in reconstructing and analyzing this, not simulating it.

6. 6 More complex geometries Arbitrarily complex geometries can be accommodated in the lcdd detector description, but these will not be propagated to the reconstruction system.  May be appropriate for supports, readouts, and far-forward BDS/MDI elements. CAD to GEANT functionality implemented, and tested for simple elements, so engineering drawings for some elements can be adopted ~as-is.  e.g. BDS elements, beampipe, etc. Will, of course, have an impact on performance due to use of BREPS in Geant.

7. 7 sid01_polyhedra Dodecagonal, overlapping stave EMCal Dodecagonal, wedge HCal Octagonal, wedge Muon Cylindrical Solenoid with substructure

8. 8 Complex Geometry & Reconstruction Propose that we continue with simplified geometries for the time being. For those detectors for which more detailed engineering designs become available, can compare performance using subdetector metrics such as tracking efficiency, resolution, etc. If time permits, can entertain the possibility of running benchmark events through improved detector designs. Reconstruction code should aim to be robust against such changes.

9. 9 Defining the Detector(s) for the LOI As the detectors become more realistic, and therefore more complex, more interaction is needed between subdetector experts and the simulation group. The sim/reco group provides the tools to define detectors, but it is the responsibility of the detector subgroups to ensure that their design is being correctly simulated. Can we find someone to take on the responsibility to lead the optimization process? Need to establish a Change Control Board for THE Silicon Detector.

10. 10 Defining sid02 Decide what needs to change from the current baseline sid01. 1. What are the “global” parameters? Can we decide? 2. How do subsystems change in reaction to this? e.g. how to interpret “make HCal 4.5 deep”  simply add more baseline layers of 2cm SS + 8mm RPC?  or change absorber layer thickness as well? e.g. “extend z of tracker volume to 2.1m”  simply stretch existing tracker barrels?  keep barrels and add extra disks?  add extra support/readout material?

11. 11 sid01  sid02 Should be able to adiabatically update sid01 design. sid01 beamcal designed for 2mr, need to change to reflect 14mr design.  Colorado group has started this, needs to be checked Beampipe design needs to be agreed upon. If we stretch the tracker and increase coil radius, will need new field map.  Does SiD want DID or anti-DID? Will vertex detector stay the same? Tracking group needs to decide on changes to outer tracker.

12. 12 sid01  sid02 Assume EM calorimeter stays the same, just extend barrel.  Is there any desire to improve the energy resolution? HCal group needs to decide how to make HCal deeper. How does Solenoid change? Muon system currently has 48 instrumented layers. How does this change?

13. 13 Detector characterization For each detector, run neutral single particles to determine calorimeter sampling fractions:  n, n,K 0 L, gamma, 10k events per run E = 1, 2, 5, 10, 20, 50, 100 GeV  = 90, 100, 110, 120, 130, 140, 150, 160, 170 Single charged particles for tracking characterization and calorimeter shower/track association   +/-,  +/-, p, K +/- Composite single particles:  0, , , , K 0 S,, etc. Single quarks (u,d,s) and Z 0 (  uds) at fixed angles and energies Dijet (uds) events at 100, 200, 500, 1000 GeV cms ZZ(  qq νν and  qqqq), ZZ, WW, Zh(qqqq, qq , qq  ), ttbar, etc. Web accessible http://www.lcsim.org/datasets/ftp.htmlhttp://www.lcsim.org/datasets/ftp.html

14. 14 slic performance @ 500GeV cms Process #jets s/event qqbar 2 48 ZZ (qq ) 2 22 ZZ (qq qq) 4 52 ttbar 6 56 Full SM ? 28

15. 15 Next Steps for LOI SM Data Sample 500GeV sample done. Have generated e + e - beam interactions at 250 GeV using GuineaPig.  Provides pair background events and beam spectra for event generation. Will soon start to produce full SM data set at 250 GeV. Need to identify exactly which files constitute the benchmark “signal” samples. Need to identify which subset of the SM sample defines the backgrounds.

16. 16 LOI Performance Metrics Although a set of benchmark processes has been identified for the LOI, the exact metrics for performance characterization have not been explicitly stated. The backgrounds to be considered, both physics and machine-related, were also never explicitly laid out. WWS Software Panel was disbanded at the ECFA-LC meeting in Warsaw, so not clear to whom this task now falls.

17. 17 Beam Background Overlays Take output from full beam simulation (from IR/backgrounds group) Feed into full detector simulation Build library of simulated background bunches Overlay backgrounds on signal events at start of reconstruction Adjust timing of hits (for TPC e.g.) Add energy in calorimeter cells Allows to change #bunches/train, bunch timing What does SiD assume for event integration?

18. 18 Event Processing & Reconstruction Have not explicitly discussed simulating the response of sid02 to the benchmark & background samples.  Computing requirements not yet clarified Which events? How many?  Computing resources at SLAC not guaranteed.  Facing “perfect storm” of BaBar reprocessing, ATLAS MC production at 10TeV, and GLAST data & MC processing.  Exploring use of grid resources at FNAL. No discussion of reconstruction.  Do not yet have production reconstruction, no idea of computing requirements. No discussion of analysis

19. 19 Summary An enormous amount of work still needs to be done just to define what the silicon detector is for the purposes of the LOI. Subsystem leaders need to make sure that their detectors are defined correctly and that the detector being simulated in the MC bears some resemblance to that being described in the rest of the LOI.  Detector needs to be debugged & characterized (e.g. sampling fractions) Event samples at 250 GeV cms need to be generated. Explicit background samples need to be identified. Benchmark measurables need to be defined. Events need to be processed through the simulation. Events need to be processed through the reconstruction. Analyses have to be developed.