July 7, 2008SLAC Annual Program ReviewPage 1 Simulation and Particle Flow Calorimetry for Future Linear Collider Detectors Norman Graf (for the Simulation & Reconstruction Team) Ron Cassell, NG, Tony Johnson, Jeremy McCormick SLAC

July 7, 2008SLAC Annual Program ReviewPage 2 Detector Simulation Mission Statement *Provide full simulation capabilities for terascale e + e - 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. *Strong connections to University groups, other labs, international colleagues. Iterate

July 7, 2008SLAC Annual Program ReviewPage 3 Goals *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. *Facilitate contribution from physicists in different locations with various amounts of available time. *Use standard data formats, when possible. *Software that is easy to install, learn, use. –Goal is to allow software to be installed from CD or web with no external dependencies. –Support via web based forums, tutorials, meetings.

July 7, 2008SLAC Annual Program ReviewPage 4 Detector Response Full Simulation MC Event (stdhep) Geometry (lcdd) Raw Event (lcio) GEANT4 slic Compact Geometry Description (compact.xml) Reconstruction, Visualization, … Use full power of Geant4 Toolkit Add functionality only where needed Use standards wherever possible.

July 7, 2008SLAC Annual Program ReviewPage 5 Detector Variants *Runtime XML format allows variations in detector geometries to be easily set up and studied: –Sampling Calorimetry Stainless Steel, W, Pb, Cu Hadron Calorimeter absorber material RPC, GEM, microMegas, Scintillator readout –Total absorption Calorimetry Crystals Dual-readout optical calorimeters –Layering (radii, number of layers, composition) –Readout segmentation (size, projective vs. nonprojective) –Tracking detector technologies & topologies Pixels, Silicon microstrip, TPC, Drift Chamber “Wedding Cake” Nested Tracker vs. Barrel + Cap –Field strength, far forward Machine Detector Interface elements

July 7, 2008SLAC Annual Program ReviewPage 6 Example Vertex Detector CAD Drawing GEANT Volumes LCIO Hits Readout digitization performed at time of reconstruction and analysis. Can study a multitude of readout technologies, pixel size, efficiencies, noise levels, etc. without rerunning full GEANT simulation. See talk by Richard Partridge for additional tracking simulations

July 7, 2008SLAC Annual Program ReviewPage 7 Silicon Detector example Dodecagonal, overlapping stave EMCal Dodecagonal, wedge HCal Octagonal, wedge Muon system Cylindrical Solenoid with substructure Silicon tracker and vertex.

July 7, 2008SLAC Annual Program ReviewPage 8 Example of Test Beam Simulation Using the same binary executable program, simply switching detector description at runtime by modifying an ASCII text file.

July 7, 2008SLAC Annual Program ReviewPage 9 Additional Applications *The flexibility and integrated sim/reco aspects of this software package make it attractive for other clients: –Being used to design detectors at CLIC. –Being considered for use in design of detectors at SuperB. –Investigating use of this package in-house to study geometries for the ATLAS pixel tracker upgrades. –Has been used for simulation of a Proton Computed Tomography (PCT) test setup at Loma Linda.

July 7, 2008SLAC Annual Program ReviewPage 10 Standard Event Samples *Generate canonical data samples and make them available to the world community. *Single particles for calibration & TB: , , e,  +/-, n, … *Composite particles:  0, , K 0 S, , , Z, … *Z Pole events: comparison to SLD/LEP *WW, ZZ, t-tbar, q-qbar, tau pairs, mu pairs, Z , Zh, … *e + e - beam pairs, muons,  hadrons, etc. backgrounds *Inclusive 2 ab -1 Standard Model sample *Web accessible *Signal and background events additive at the detector hit level, with time offsets. –Fully and flexibly investigate effects of backgrounds in analyses.

July 7, 2008SLAC Annual Program ReviewPage 11 Reconstruction *Core reconstruction algorithms (track finding, fitting, calorimeter clustering, etc.) are in place. *Interfaces defined for tasks, with many different plug-&- play implementations (e.g. calorimeter clustering). –Decouples interdependencies of different tasks. –Allows comparisons between different algorithms or implementations. –Easily swap in MC “cheater” to study effects of particular analysis task, independent of other tasks. –Physics analyses can be developed and tested using fast Monte Carlo smearing, seamlessly transition to full reconstruction. *Standardized algorithm comparison tools. *Use common event data model and persistency (LCIO) –allows interchange of data and code between regional efforts.

July 7, 2008SLAC Annual Program ReviewPage 12 “Particle Flow” Calorimetry *Precision analyses of final state processes with low cross sections argues for di-jet mass resolution similar to the gauge boson widths. Want to distinguish between W/Z  qq’  dijets. *Assuming a single jet energy resolution of normal form: *Suggests, for typical dijet energies of GeV, a jet energy resolution goal of

July 7, 2008SLAC Annual Program ReviewPage 13 Individual Particle Reconstruction *Highly efficient tracker measures charged particles with excellent momentum resolution. *Goal is to reconstruct individual showers in the calorimeters and associate them with the correct tracks. *Measure photons in highly segmented electromagnetic calorimeter with reasonable energy resolution. *Hadronic calorimeter measures energy of neutral hadrons.

July 7, 2008SLAC Annual Program ReviewPage 14 Detector Design *Require an integrated detector design, but the calorimetry is the crux of the problem. *Confusion is the largest term  “imaging” calorimetry *EM Calorimeter: dense, small Moliere radius –fine transverse segmentation to accurately determine photon shower locations and direction –fine longitudinal segmentation for efficient charged particle tracking through the EM Cal, and to separate charged and neutral particle showers. *Hadron Calorimeter: Emphasize segmentation & granularity (transverse & longitudinal) over intrinsic energy resolution.

July 7, 2008SLAC Annual Program ReviewPage 15 Ultimate Resolution Z lineshape 23%/  E Ultimately, the criterion for the best jet energy resolution is the necessary physics performance, balanced by the detector cost. Simple four-vector smearing studies (i.e. no confusion) indicate that ~ 17%/  E could be achievable. Improved resolution results in more effective luminosity, so detector cost needs to be balanced against the cost of running the machine. Very complicated optimization process! M. Thomson

July 7, 2008SLAC Annual Program ReviewPage 16 GEANT4 *Stringent requirements on the detector performance and the ability to model many different detectors have resulted in the discovery of a number of features in Geant4 over the years: –Energy loss and multiple scattering errors in precision tracking. –Momentum and energy non-conservation in shower models. –Discontinuities in shower shapes from model overlaps. –Strong energy dependence of energy depositions on range cuts. –… *Active participation in Geant4 technical forum discussions. *Not just using Geant4, but returning improvements to the community.

July 7, 2008SLAC Annual Program ReviewPage 17 Peer Review *DOE-NSF Review of US Program for Detector R&D, June 19, 2007, ANLDOE-NSF Review of US Program for Detector R&D Consultants: Tim Bolton (Kansas State), David Cassel (Cornell), Gary Feldman (Harvard), Meenakshi Narain (Brown), Regina Rameika (FNAL), Michael Rijssenbeek (Stony Brook), Bing Zhou (Michigan) Funding Agency representatives: Jim Whitmore (chair, NSF), Paul Grannis (DOE) and Howard Nicholson (DOE). Observers: Jerry Blazey (NIU), Chris Damerell (RAL), Bill Willis (Columbia University) *Committee Recommendations:Committee Recommendations + “Standard benchmark processes, both high level (Higgs mass resolution, chargino mixing angles etc.) and low level (tau id efficiency, jet energy resolution etc.) should be agreed upon by the global detector organization and used to compare the technologies and detector concepts under consideration.” - “Support should be increased immediately by 2-3 FTEs for software algorithm developments both on the PFA efforts, and for track reconstruction in jets, particularly for forward track reconstruction.”

July 7, 2008SLAC Annual Program ReviewPage 18 Resources for getting started * Web Sitehttp://lcsim.org/ –Documentation & Tutorials Software installation Using tools Simple Analysis Examples Developers Guide –Datasets *Confluence Wiki –More documentation & tutorials –Frequently asked Questions –Users are encouraged to comment on, add to, or correct existing documentation *Discussion Forums –

July 7, 2008SLAC Annual Program ReviewPage 19 Summary *SLAC Simulation & Reconstruction team supports an ambitious physics and detector simulation, reconstruction & analysis effort. *Goal is flexibility and interoperability, not technology or concept limited. *Provides full data samples for precision terascale e + e - physics studies. *Provides a complete and flexible detector simulation package capable of simulating arbitrarily complex detectors with runtime detector description. –Has been used or is being considered for use in designing detectors in other disciplines or fields. *Reconstruction & analysis framework exists, core functionality available, individual particle reconstruction template developed, various analysis algorithms implemented. *Currently engaged in characterizing and optimizing the performance of the silicon detector concept (SiD).

July 7, 2008SLAC Annual Program ReviewPage 20 Additional Information *Web Portal - *Discussion Forum - *Wiki - *Detector response simulation software - *Event reconstruction software - *Software Index - *Detectors - *Event data model and persistence format - *Detector geometry description - *Integrated Development Environment *Histogramming, fitting, analysis - *Event Display -

July 7, 2008SLAC Annual Program ReviewPage 21 Backup Slides

July 7, 2008SLAC Annual Program ReviewPage 22 The Grid *Existing resources have proven sufficient to-date for event generation, detector response simulation and reconstruction/analysis, but changes in SCCS fair-share allotments necessitate move to the grid. *Grid tools seem to be getting to the point where they are useful, so are beginning the transition. *Tools have been developed from the beginning to be grid friendly, i.e. static binaries, no db connections, … *Have developed (SBIR w/ Tech-X) Interactive Dataset Analysis on the Grid tools (as opposed to normal batch processing). –Plug-in allows grid analysis from within JAS.