1. Intelligent Norman Graf (SLAC) SuperB computing mini-Workshop Pearl Harbor Day, 2007 DesignDetector

2. 2 Linear Collider Detector Environment Detectors designed to exploit the physics discovery potential of e + e - collisions at  s ~ 1TeV. Perform precision measurements of complex final states with well-defined initial state: –Tunable energy –Known quantum numbers & e ─, e +,  polarization –Possibilities for ,  e ─, e ─ e ─ –Very small interaction region –Momentum constraints (modulo beam & bremsstrahlung)

3. 3 LCD Simulation Mission Statement Provide full simulation capabilities for Linear Collider physics program: –Physics simulations –Detector designs –Reconstruction and analysis Need flexibility for: –New detector geometries/technologies –Different reconstruction algorithms Limited resources demand efficient solutions, focused effort.

4. 4 Overview: Goals Facilitate contribution from physicists in different locations with various amounts of time available. Use standard data formats, when possible. Provide a general-purpose framework for physics software development. Develop a suite of reconstruction and analysis algorithms and sample codes. Simulate benchmark physics processes on different full detector designs.

5. 5 Fast Detector Response Simulation Covariantly smear tracks with matrices derived from geometry, materials and point resolution using Billoir’s formulation. http://www.slac.stanford.edu/~schumm/lcdtrk Derivative of TRKERR. Provides smeared tracks with full covariance matrix.

6. 6 lelaps Fast detector response package. Handles decays in flight, multiple scattering and energy loss in trackers. Parameterizes particle showers in calorimeters. Produces lcio data at the hit level. Uses runtime geometry (compact.xml  godl). An excellent tool for designing tracking detectors! http://lelaps.freehep.org/index.html

7. 7 Ω  → Ξ 0 π - Ξ 0 → Λ π 0 Λ → p π - π 0 → γ γ as simulated by Lelaps for the LDC model. Lelaps: Decays, dE/dx, MCS gamma conversion as simulated by Lelaps for the LDC model. Note energy loss of electron.

8. 8 Detector Design (GEANT 4) Need to be able to flexibly, but believably simulate the detector response for various designs. GEANT is the de facto standard for HEP physics simulations. Use runtime configurable detector geometries Write out “generic” hits to digitize later.

9. 9 Full Detector Response Simulation Use Geant4 toolkit to describe interaction of particles with matter. Thin layer of LC-specific C++ provides access to: –Event Generator input ( binary stdhep format ) –Detector Geometry description ( XML ) –Detector Hits ( LCIO ) Geometries fully described at run-time! –In principle, as fully detailed as desired. –In practice, will explore detector variations with simplified approximations.

10. 10 LC Detector Full Simulation MC Event (stdhep) Geometry (lcdd) Raw Event (lcio) GEANT4 slic Compact Geometry Description (compact.xml) Reconstruction, Visualization, …

11. Geometry System GDML LCDD Expressions (CLHEP) Materials Solids Volumes Identifiers Sensitive Detectors Regions Physics Limits Visualization Magnetic Fields

12. Geant4 Data Binding AreaRoot ElementGeant4 Class(es) Sensitive Detectors G4VSensitiveDetector Identifiers NA (custom classes) Regions G4Region, G4VUserRegionInformation Physics Limits G4UserLimits Visualization G4VisAttributes Magnetic Fields G4MagneticField Constants NA (CLHEP expressions) Materials G4Material, G4Element Shapes G4VSolid Volumes G4LogicalVolume, G4VPhysicalVolume

13. LCDD XML Format – reference to subdetector – reference to region – reference to limits – reference to vis attributes Volume Extensions – identifier - sensitive detector – geometry region – set of physics limits – visualization attributes Core Elements references Container Elements GDML

14. Volume Element

15. Sensitive Detectors and Identifiers Sensitive Detectors Identifiers

16. Regions, Fields & Limits Physics Limits Regions <region name="TrackingRegion" store_secondaries="true" cut="10.0" lunit="mm" threshold="1.0" eunit="MeV"> <solenoid name="GlobalSolenoid" inner_field="solenoid_inner_field" outer_field="solenoid_outer_field" zmin="solenoid_zmin" zmax="solenoid_zmax" inner_radius="solenoid_rmin" outer_radius="solenoid_rmax" funit="tesla" lunit="mm"/> Fields

17. Compact Description Example <detector id="2" name="EMBarrel" type="CylindricalBarrelCalorimeter" readdout="EcalBarrHits"> Two different layer stacks in same Ecal.

18. SLIC Overview C++ user application using Geant4 toolkit hub package  most of functionality implemented in subpackages standard data formats for ILC LCIO (output): HEP data model with generic Calorimeter and Tracker hits StdHep (input): physics events LCDD (input): GDML-based geometry system command line or macro commands / interactive

19. SLIC Diagram StdHep Physics Events LCDD XML Geometry SLIC Geant4 Simulator LCIO Output File Compact XML Geometry Reconstruction & Visualization Simulator for the Linear Collider (SLIC) Linear Collider Detector Description (LCDD) Geometry Description Markup Language (GDML) Linear Collider IO (LCIO) translated to writes reads / writes reads

20. SLIC Commands All command-line options have equivalent Geant4 command Sample command slic -g geometry.lcdd -i events.stdhep -x -O -l LCPhys -r 1000 Equivalent macro /lcdd/url geometry.lcdd /run/initialize /physics/select LCPhys /generator/filename events.stdhep /lcio/fileExists delete /lcio/autoname /run/beamOn 1000

21. Diagnostic Histograms Diagnostic plots of event data MCParticles, hits, clusters Runs on different detectors must have compact description also need sampling fractions Easy to use and setup SLAC CVS project cvs –d :pserver:jeremy@cvs.freehep.org:/cvs/lcd co SlicDiagnostics./build.sh./bin/SlicDiagnostics [...]

22. LCIO Overview Object model and persistency Events Monte Carlo Raw Event and run metadata Reconstruction Parameters, relations, attributes, arrays, generic objects, … All the ILC simulators write LCIO Enables cross-checks between data from different simulators Read/write LCIO from Fast MC / Full Simulation Different detectors Different reconstruction tools

23. Physics Lists: LCPhys standard Geant4 EM physics hadronic models Bertini Cascade 0 to 9.9 GeV for p, n, pi+, pi- 0 to 13 GeV for K+, K-, K0L, K0S, Lambda, Sigma+, Sigma-, Xi0, Xi- Low energy parameterized models 9.5 to 25 GeV Quark-Gluon String Model: use for 12 GeV to 100 TeV for p, n, pi+, pi-, K+, K-, K0L, K0S additional neutron processes neutron-induced fission neutron capture gamma-nuclear

24. Other Available Physics Lists FTFC Fritjof with CHIPS FTFP Fritjof with precompound LHEP low / high energy parameterised QGSC Quark-Gluon String with CHIPS QGSP Quark-Gluon String with precompound QGSP_BERT Quark-Gluon string with precompoind + Bertini Cascade LHEP_BERT low / high energy parameterised + Bertini Cascade

25. Event Sources General Particle Source (GPS) advanced single particle source builtin to Geant4 angular distributions randomized energy one or more particles generate in volume (box, tube, etc.) StdHep common binary format for event generators HEPEVT block your favorite event generator PYTHIA, HERWIG, WHIZARD, etc. LCIO converts LCIO MCParticle block into G4PrimaryParticles read output from other simulators (Mokka, JUPITER, etc.) EXPERIMENTAL

26. Event Source Conversion use LCIO MCParticle data structure for bookkeeping during simulation\\ GPS or G4ParticleGun no initial MCParticle collection necessary convert directly from Geant4 trajectory container StdHep or LCIO event source create initial LCIO MCParticle tree make G4PrimaryParticles for each MCParticle if travels > mininum tracking distance intermediate or final (documentation not tracked) predecays preassigned decays from the generator assign time, daughters, etc. Geant4 may still override (e.g. if it interacts before predecay occurs) no vertex  determined from parent particle

27. Software Distribution SLIC requires Geant4, CLHEP, GDML, LCDD, Xerces, LCPhys, LCIO Automated build system provided Binary downloads http://www.lcsim.org/dist/slic Linux, Windows (Cygwin), OSX All packages (dist) or just runtime dependencies (bin) Or checkout and build from scratch cvs –d :pserver:anonyous@cvs.freehep.org:/cvs/lcd co SimDist cd SimDist;./configure; make Installed at SLAC, NICADD, FNAL, IN2P3, UC,... Report any problems to jeremym@slac.stanford.edujeremym@slac.stanford.edu

28. 28 GeomConverter Compact Description GeomConverter LCDD GODL org.lcsim Analysis & Reconstruction HEPREP Small Java program for converting from compact description to a variety of other formats slic lelaps wired lcio

29. 29 Detector Variants Runtime XML format allows variations in detector geometries to be easily set up and studied: –Stainless Steel vs. Tungsten HCal sampling material –RPC vs. GEM vs. Scintillator readout –Layering (radii, number, composition) –Readout segmentation (size, projective vs. nonprojective) –Tracking detector technologies & topologies TPC, Silicon microstrip, SIT, SET “Wedding Cake” Nested Tracker vs. Barrel + Cap –Field strength –Far forward MDI variants (0, 2, 14, 20 mr )

30. 30 Example Geometries MDI-BDS Cal Barrel SiD SiD Jan03 Test Beam Cal Endcap

31. 31 Far forward calorimetry boolean solids polycones Machine Detector Interface and Beam Delivery System

32. 32 Summary The American Linear Collider Physics Group simulation group has developed a suite of tools being used to design detectors for the ILC. Flexible, fully-featured Geant4-based detector response simulator, slic, uses runtime detector geometry description. –Supports arbitrarily complex geometries (lcdd) –Many elements common to collider detectors are also available through a compact description provides bindings to fastMC, visualization, reconstruction.

33. 33 Additional Information Wiki - http://confluence.slac.stanford.edu/display/ilc/Homehttp://confluence.slac.stanford.edu/display/ilc/Home lcsim.org - http://www.lcsim.orghttp://www.lcsim.org org.lcsim - http://www.lcsim.org/software/lcsimhttp://www.lcsim.org/software/lcsim Software Index - http://www.lcsim.org/softwarehttp://www.lcsim.org/software Detectors - http://www.lcsim.org/detectorshttp://www.lcsim.org/detectors ILC Forum - http://forum.linearcollider.orghttp://forum.linearcollider.org LCIO - http://lcio.desy.dehttp://lcio.desy.de SLIC - http://www.lcsim.org/software/slichttp://www.lcsim.org/software/slic LCDD - http://www.lcsim.org/software/lcddhttp://www.lcsim.org/software/lcdd JAS3 - http://jas.freehep.org/jas3http://jas.freehep.org/jas3 AIDA - http://aida.freehep.orghttp://aida.freehep.org WIRED - http://wired.freehep.orghttp://wired.freehep.org

34. Maryland Physics Department Colloquium 34 xml: Defining a Module <module_component width="7.6" length="125.0" thickness="0.26" material="CarbonFiber" sensitive="false"> <module_component width="7.6" length="125.0" thickness="0.05" material="Epoxy" sensitive="false"> <module_component width="9.6" length="125.0" thickness="0.1" material="Silicon" sensitive="true">

35. Maryland Physics Department Colloquium 35 xml: Placing the modules

36. Maryland Physics Department Colloquium 36 The Barrel Vertex Detector

37. Maryland Physics Department Colloquium 37 LCIO SimTracker Hits from Vertex CAD Drawing GEANT Volumes LCIO Hits