Simulation Framework Norman Graf SLAC June 10, 2005

Simulation Point-of-contact Linear Collider Detector Simulation portal is: www.lcsim.org Contains links to: Software Datasets Detectors Resources linearcollider.org forum ILC confluence Wiki Simulation Groups Regional simulation groups (ALCPG, ACFA, ECFA)

Code & Data Access All simulation & reconstruction code publicly available. Code is managed via cvs, can be checked out anonymously. tortoiseCVS is very nice client for Windows Data samples available via anonymous ftp.

Event Generation Provide pre-generated events and functionality to generate custom datasamples. full SM samples from whizard @ 350, 500, 1000 GeV used NLC parameters, ILC samples available by Snowmass “Signal” samples (pandora-pythia) ILC500 & ILC1000 mumu, qqbar, tautau, WW, ZZ, Zgamma, ttbar, ZH diagnostic events “single” particle events of increasing complexity covering various regions of phase space. Bindings to pythia, herwig, isajet, etc. Any binary stdhep events can be used as input.

Detector Response Simulation Use Geant4 toolkit to describe interaction of particles with matter. Thin layer of LC-specific C++ (slic): 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.

Vertex Detector 5 Layer CCD Barrel 4 Layer CCD Disks Be supports Foam Cryostat <detectors> <detector id="0" name="BarrelVertex" type="MultiLayerTracker" readout="VtxBarrHits"> <layer id="1" inner_r = "1.5*cm" outer_z = "6.25*cm"> <slice material = "Silicon" width = "0.01*cm" sensitive = "yes" /> </layer> <layer id="2" inner_r = "2.6*cm" outer_z = "6.25*cm"> <layer id="3" inner_r = "3.7*cm" outer_z = "6.25*cm"> <layer id="4" inner_r = "4.8*cm" outer_z = "6.25*cm" > <layer id="5" inner_r = "6.0*cm" outer_z = "6.25*cm"> </detector>

Central Tracking Detector 5 Layer Si -strips Barrel+Disk C-Rohacell-C supports <detector id="2" name="BarrelTracker" type="MultiLayerTracker" readout="TkrBarrHits"> <layer id="1" inner_r = "18.635*cm" outer_z = "26.67*cm"> <slice material = "CarbonFiber" width = "0.025*cm" /> <slice material = "Rohacell31" width="1.3*cm" /> <slice material = "CarbonFiber" width=".025*cm" /> <slice material = "Silicon" width = "0.03*cm" sensitive = "yes" /> </layer> <layer id="2" inner_r = "44.885*cm" outer_z = "61.67*cm">

Detector Designs One source for simulation and reconstruction detector geometry, compact.xml. Detectors uniquely specified by name, e.g. sidmay05 GeomConvert package converts this terse representation into: full detector description in lcdd format  slic heprep  WIRED event display org.lcsim detector descriptions, allows id decoding local-to-global & global-to-local geometry

Detector Designs CVS: :pserver:anonymous@cvs.freehep.org:/cvs/lcd module LCDetectors Index of released detectors automatically generated and posted to web at: http://www.lcsim.org/detectors/

Detector Variants XML format allows variations in detector geometries to be easily set up and studied: Number and spacing of tracker/vertex layers Tracking detector topologies “Wedding Cake” Nested Tracker vs. Barrel + Cap Field strength Readout segmentation deferred to “analysis” stage; adds additional level of flexibility in studying detector variants. Detector tiling, pixel size, strip pitch/orientation, etc.

Tiling Forward Disks Large Angle Stereo Shallow Angle Stereo

Tiling Disks with Wedges Code exists to tile forward disks with wedges Allows one to construct a tiling of a disk with just a few input parameters: number of annuli number of wedges per annulus inner radii of annuli outer radii of annuli phi offset of wedges in annulus strip pitch orientation of strips

Example Disk Tiling

Alternate Tilings Hexagonal or square tiling of forward disks are also an alternative. Some work has been done along these lines (R. Partridge), but not released.

Tracking Detector Readout Hits in Trackers record full MC information. Digitization is deferred to analysis stage. Nick Sinev has released a package to convert hits in silicon to CCD pixel hits. MC Hits Pixels & PH Clusters Hits (x ± x) UCSC developed long-shaping-time -strip sim. MC Hits Strips & PH Clusters Hits ( ± ) Needs to be ported from hep.lcd to org.lcsim!

SimTrackerHit  TrackerRawData Digitization SimTrackerHit  TrackerRawData ID ADC counts (first) time true position time energy deposited link to MC Particle momentum stored in LCRelation

Clustering Associate contiguous strip hits into clusters Determine cluster position and uncertainty Feed back to pattern recognition code.

Track Finding (hep.lcd) Nick Sinev has released standalone pattern recognition code for the 2D VXD hits. High efficiency, even in presence of backgrounds. Efficient at low momentum. Propagates tracks into Central Tracker to pick up  hits Conformal-mapping pattern recognition also available. Fast, but not yet tuned (97% vs 99+%). Work also ongoing to find MIP stubs in Cal and propagate inwards (Kansas State, Iowa).

Forward Track Finding

To do Digitize hits into readout strips, cluster strips and create strip hit positions and uncertainties. Study occupancies as a function of various disk-tiling geometries. can introduce pixels into innermost rings if needed. Quantify number of ghost hits for various geometries. Can we do standalone tracking in disks/outer barrels? Conduct studies with full backgrounds.

Code Development Strongly encourage developers to use an Integrated Development Environment (IDE) Code can be developed using Notepad/emacs/JAS, but efficiency is much higher using Netbeans or Eclipse editor integrated with API documentation tab-completion of class methods debugger refactoring http://confluence.slac.stanford.edu/display/ilc/org.lcsim

Summary Framework exists for straightforwardly defining detector geometries. Digitization of tracker hits at analysis stage provides more degrees of freedom (pixel size, strip pitch, length, orientation, …) Reconstruction & analysis framework is ~available, tuning and improvements welcomed. Data samples for several configurations available. Characterize performance of SiD and variants by/at Snowmass.