1. Simulation Framework
Norman Graf
SLAC
June 10, 2005

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

3. 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.

4. Event Generation
Provide pre-generated events and functionality to generate custom datasamples.
full SM samples from 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.

5. 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.

6. 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>

7. 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">

8. 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

9. Detector Designs
CVS:
module
LCDetectors
Index of released detectors automatically generated and posted to web at:

10. 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.

11. Tiling Forward Disks
Large Angle Stereo
Shallow Angle Stereo

12. 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

13. Example Disk Tiling

14. 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.

15. 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!

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

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

18. 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).

19. Forward Track Finding

20. 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.

21. 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

22. 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.