1. Testbeams for Simulation
Norman Graf
ECFA LC Workshop, Durham
September 2, 2004

2. Problem Statement
Primary goal for testbeam is to validate detector technology.
However, since we are designing detectors based on simulation studies, we also need to validate the simulations.
GEANT3 offered relatively few options for modeling hadronic showers.
TB data-simulation discrepancies accepted.
Used primarily for energy resolution.

3. Geant4 hadronic shower models.
GEANT4 has extensive set of hadronic shower models, from which we would like to select.
Several experiments have compared testbeam data with Geant4 predictions.
However, used to characterize existing designs, not to design new detectors.
“Particle Flow”, or imaging calorimeter, places much more stringent requirements on simulation.
Cottage industry to run all available sets to demonstrate dispersion.
See talks in simulation session.

5. Feedback from Testbeam
Would like input from testbeam to provide guidance not only in selecting from existing models, but to improve existing models.
Would like to see as broad a spectrum of particle type and momentum as possible.
Emphasis on lower energies.
Kaons needed!
Detailed longitudinal and transverse shower shapes.
Time evolution of shower if possible.

6. Physics Lists for LC
Provide a “standard” Geant4 physics list to be used in study of LC detectors
Make the list easy to use and understand
Keep it up-to-date as new models become available
Validate as test beam data becomes available
Include it in LC Geant4 example (Makoto Asai)

7. Physics List Design Provide only one list everyone can use
Specialized lists could be added later
Avoid hadronic list libraries
These are nice, but too general and somewhat involved
Write out a “long-hand” physics list
Derived from G4VModularPhysicsList
Everything contained in 12 files
Easy to see what processes/models are used and how they are invoked

8. Justification of Model Choices: Below 20 GeV
Between 10 and 20 GeV, only one model available:
LEP
Below 10 GeV, three models to choose from:
Low energy parameterized (LEP) : for all particles
Bertini cascade: for p, p, n only
Binary cascade: for p, p, n only
Pion production reactions clearly eliminate LEP
Bertini and Binary equally good, Bertini 8x faster
So LEP plus Bertini cascade required in list

9. Maintenance and Use Dennis Wright (SLAC) developing and maintaining.
Physics list will be maintained in FreeHEP CVS
Anyone can get it:
cvs -d LCPhys
Better models, bug fixes will be included as available
Questions, problems to

10. TB Simulations
Detector geometries fairly straightforward, but require ability to define all parameters as realistically as possible.
Will need commensurate simplified geometries for full detector simulations.
TBMokka requires new driver for each setup.
Inefficient, prone to error, hard to maintain (copy/paste).
Need revision of Mokka concept.
DESY, NICADD, SLAC collaborating on development.
Need requirements from users!