SLIDE 1
Status of the BaBar Simulation Geant4 Workshop 30 September 2002 - - PowerPoint PPT Presentation
Status of the BaBar Simulation Geant4 Workshop 30 September 2002 - - PowerPoint PPT Presentation
Status of the BaBar Simulation Geant4 Workshop 30 September 2002 Dennis Wright Outline BaBar Overview Comparison projects EM process validation Hadronic process validation Performance The BaBar Detector Overview of the BaBar
SLIDE 2
SLIDE 3
The BaBar Detector
SLIDE 4
Overview of the BaBar Simulation
Objectivity Database Event Generator
Tracking, Physics, Hit Scoring
(Bogus, GEANT4)
Detector Response And Background Mixing (SimApp) Reconstruction And Analysis (Bear)
SLIDE 5
Use of Geant4 in BaBar
BaBar uses:
– Geometry – Hit-scoring – Decay processes – EM physics processes (< 10 GeV) – Low energy hadronic processes (< 10 GeV)
BaBar does not use:
– Standard tracking/navigation – Detector response – Persistence
SLIDE 6
BaBar/Geant4 Validation (1)
1 million events generated by October 2000
– B0B0bar, Bhabha, dimuons
Use to test gross features of simulation:
– Material model validation – Tracking/resolution tests – G3/G4/Data comparison of EM processes – Rough check of hadronic processes – Tests of performance/robustness
SLIDE 7
BaBar/Geant4 Validation (2)
Detailed comparisons of MC and data
– 11 million event sample completed July 2002
- > 25 different event types simulated
– Goals:
- fine tuning of EM processes (check recent improvements)
- Take a serious look at hadronic processes
- Examine calorimetry, tracking, PID
SLIDE 8
EM processes/calorimetry
SLIDE 9
EM processes/calorimetry
SLIDE 10
EM processes/calorimetry
SLIDE 11
Tracking
SLIDE 12
Tracking
SLIDE 13
Hadronic Validation
Currently using low energy parameterized model
– Not especially appropriate for BaBar energies (50 MeV – 10 GeV) – Several fixes reported by LCD group at SLAC – passed to G4 – Some included in toolkit, some to be included soon
Use latest MC data set and BaBar “thin target” tests to search for and fix other problems Very recent results from tests –hadronic group hasn’t seen them yet
SLIDE 14
BaBar “Thin Target” Hadronic Tests
SLIDE 15
SLIDE 16
SLIDE 17
Hadronic Validation
Hadron kinetic model (40 MeV – 10 GeV) will be perfect for BaBar
– Will switch to that as soon as it is ready
SLAC (T. Koi, D. Wright) has recently joined in the hadron kinetic model validation effort First effort – develop validation test bench for p,n, pi, K
– Compare data, kinetic model at 500 MeV – few GeV
SLIDE 18
Performance (1)
Simulation stage of generic B0-B0bar event includes event generator, tracking, hit-scoring
– On 866 MHz PIII takes 5.0 s/evt – Used Geant4 4.0
Currently running MC production at 19 sites (1 billion events so far) Run failures due to Geant4 getting rare
– < 1 per million events – A few annoyances remain
SLIDE 19
Performance (2)
BaBar recently decided to double the MC/data ratio (to 3) Speed issues now more important than ever Geant4 part of BaBar simulation time 30-40% Options:
– Simplify detector geometry – Use parameterized showers – Use faster machines (new 1.4 GHz machines being tested)
SLIDE 20