1. Linear Collider Simulation Tools
Norman Graf
ECFA LC Workshop
Durham, Sep. 4, 2004

2. Detector Requirements
Detectors designed to exploit the physics discovery potential of e+e- collisions at s ~ 1TeV.
Will perform precision measurements of complex final states.
Require:
Exceptional momentum resolution
Excellent vertexing capabilities
“Energy Flow” calorimetry
Hermeticity
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Norman Graf

3. Detector Requirements
Yes, but still need to quantify!
Exceptional momentum resolution
is dp/p ~ few 10-5 really necessary!
How important is material?
Excellent vertexing capabilities
What are the effects of inner radius, thickness, number of layers
“Energy Flow” calorimetry
Is 30%/E needed? Can we do better?
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Norman Graf

4. Particle Flow Motivation
Measure momenta of charged tracks in the tracker with superb resolution.
Measure photons in highly segmented EM calorimeter with reasonable resolution.
Remaining neutral hadrons measured in hadron calorimeter.
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Norman Graf

5. No tool is too simple…
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Norman Graf

6. Tracker Resolution Tool lcdtrk
Bruce Schumm has developed a nice tool which allows rapid investigation of tracker designs.
Input is simplified geometry, materials and point resolution.
Output is resolution plots plus covariance matrices which can immediately be used to smear tracks in the fast Monte Carlo.
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Norman Graf

7. Fast MC Covariantly smears charged tracks.
Smears neutral calorimeter showers by expected resolutions.
Can be used as input for further analyses.
Jet Finding
ZVTop vertexing
Can vary resolutions at analysis time and produce plots of x vs resolution, eff., etc.
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Norman Graf

8. LC Detector Full Simulation
MC Event
G4Application
Raw Event
Geometry
Geometry
Database
GEANT4
Reconstruction, Visualization, …
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Norman Graf

9. LCD Full Simulation Geometry defined in XML.
Flexible, but simplified volumes.
Projective readout of sensitive volumes.
Dynamic topology, not just parameters.
Have defined generic hit classes for sensitive tracker and calorimeter hits.
LCIO bindings for I/O.
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Norman Graf

10. LC Detector Simulations
Use simplified volumes to investigate larger number of designs, allowing dynamic topologies using single executable.
Describe “optimal” detector in detail.
TPC Tracker, Si Disks, CCD VTX
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Norman Graf
All Si Tracker, CCD VTX

11. Reconstruction/Analysis Overview
Java based reconstruction and analysis package
Runs standalone or inside Java Analysis Studio (JAS)
Fast MC
Smeared tracks and calorimetry clusters
Full Reconstruction
track finding and fitting
calorimeter clustering
Individual Particle reconstruction (cluster-track association)
Analysis Tools (including WIRED event display)
Physics Tools (Vertex Finding, Jet Finding, Flavor Tagging)
Beam Background Overlays
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Norman Graf

12. hep.lcd Physics Utilities
4-vector, 3-vector classes
Event shape/Thrust finder
Jet Finders
Many kT algorithms implemented (e.g. Jade and Durham )
Extensible to allow implementation of other algorithms
Event Display
Topological Vertexing
Implementation of SLD’s ZVTOP
Event Generators
Can be run directly in FastMC
Can be run standalone, e.g. for writing stdhep files
Diagnostic Generator
User-defined particle mix, momenta and vertices.
Generator framework extensible for other generators
PYTHIA, HERWIG, ISAJET, …
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Norman Graf

13. hep.lcd analysis tools
Tutorial:
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Norman Graf

14. WIRED3 Event Display
Tree controls visibility. (HepRep2 support in WIRED3 is preliminary)
Picking supports viewing physics attributes
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Norman Graf

15. Reconstruction Status
Full Reconstruction package which incorporates all aspects of the Particle Flow paradigm, works for any detector, and works out-of-the box is not currently available.
However, many of the pieces are in place, can be used today, & active work is underway to incorporate into a finished product.
See talks in simulation session.
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Norman Graf

16. Testing Samples
Testing reconstruction on simple events. Study finding efficiency, fake rates and measurement resolutions (E, p, mass) using:
Single Fundamental Particles
e+/-, , +/-, +/-
Simple Composite Single Particles
0, , , , 
Complex Composite Single particles
Z, W
Physics Events
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Norman Graf

17. Conclusions
A fairly complete suite of simulation tools exists for LC physics and detector studies.
Contributions to the full reconstruction welcomed and invited, but much can be done within the existing framework with released software.
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Norman Graf

18. 11/28/2018
Norman Graf

19. Most important tool of all!
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Norman Graf

20. Links LC Simulations: http://lcsim.org
JAS3:
WIRED:
Discussion Forums:
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Norman Graf