1. Simulation Project Structure and tasks
Simulation Project (G.Cosmo)
Coordination
Geant4
collaboration
Geant4 (J.Apostolakis)
LHC-oriented development and support of Geant4 toolkit
Fluka (A.Ferrari)
LHC-oriented development and support of Fluka
FLUKA
collaboration
Garfield (R.Veenhof)
Development, support and interfaces
Experiments
Validation
Physics Validation & Simulation Framework (A.Ribon)
Validation of the detector simulation MC engines
Generator Services (A.Ribon, W.Pokorski from Feb-2010)
Event generators repository, generator validation, HepMC
MC4LHC
LCG Simulation Project

2. LCG Generator Services
GENSER
Structure stable and used by experiments
26 generators installed (most with different versions)
Autotools ready for all generators
“bootstrap” script ready for building GENSER more easily and everywhere
Completed migration to SLC5
Adopted HepMC Analysis Tool for regression testing based on distributions; evaluation of Rivet also for regression testing
HepMC
New release in progress, expected in March
Nightly builds for testing HepMC in preparation
MCDB
In use for CMS productions
LCG Simulation Project

3. LCG Physics Validation
Main effort to improve the transition between hadronic models in Geant4
Physics Lists with different transition regions: e.g. FTFP_BERT_TRV (as FTFP_BERT but with transition between Fritiof and Bertini between 6 – 8 GeV, instead of 4 – 5 GeV)
New combinations of models: e.g. QGSP_FTFP_BERT (like QGSP_BERT, but with Fritiof replacing LEP, transition 6-8 GeV
Improvement of Geant4 models (next text slide)
Regular feedback from LHC test-beam analyses
ATLAS HEC, ATLAS TileCal, CMS HCAL
New validation results from CALICE test-beam
Very granular calorimeter sensitive to details of hadronic showers
LCG Simulation Project

4. LCG Simulation Project
E. Garutti: LCG Phy. Val. meet. 10 June 2009
CALICE Preliminary
LCG Simulation Project

5. Geant4 Hadronic Physics Progress (Release 9.3 – Dec 2009)
Improvement of Fritiof-based FTF model
Tuning for energies 3-8 GeV
Added Reggeon cascade - as back-end
Better matching with Bertini
New CHIPS hadronic interaction (1st release)
Use single model for all Energies => smooth response
Improvement and parameter tuning underway
Corrected internal cross sections in BERTini
At energies below 1 GeV (SLAC Geant4 team)
Retuned Multiple Scattering for e+/e- (optional)
FTF: As a result the FTFP_BERT physics list now provides smooth energy-response,
and agrees at low and high energies with the (best current) physics list QGSP_BERT – but does not have its unphysical dips
In Bertini:
The nucleon-nucleon and pion-nucleon partial cross-sections used in the Bertini cascade were reviewed and the incorrect cross-sections found below 1 GeV were fixed. This results in slightly improved agreement with data below 1 GeV.
LCG Simulation Project

6. Geant4: Performance and Support
Computing Performance
Support and patching
Reduced number of memory allocations
In geometry, hadronics (reports of ATLAS, CMS)
Reduced number of costly field calls
Adapting stepper created by ATLAS
Support for issues in LHC experiment productions
patches
Will provide patches for 9.2 until December 2010
Fixes
Some CPU improvements
LCG Simulation Project

7. Current LCG Simulation manpower
As of Feb 2010
Geant4
6.70
(5.70)
Infrastructure, performance, management (approx)
1.55
Electromagnetic / Hadronic Physics effort (approx)
4.40
(3.40)
Geometry, tracking, biasing (approx)
0.75
CERN staff (3.50 -> 3.20), CERN fell./assoc./stud. (3.20 -> 2.50)
Physics validation & Framework
1.00
(0.80)
Validation specific to experiments
0.00
Generator services
2.40
management, documentation/release
0.30
GENSER dev., Validation, MCDB
2.10
Fluka
Garfield (interface library to Geant4)
0.20
Management
0.25
Total
10.55
(9.35)
9.85 in July 2009
(x.xx) Manpower as of July 2010
LCG Simulation Project