Part IV
Geant4 results
Maria Grazia Pia, INFN Genova
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Overview of applications
and results
Geant4 is used in a wide variety of experiments and fields
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the future LHC experiments
neutrino and astroparticle physics
experiments
space science
astrophysics
X-ray analysis
medical physics
theoretical applications
...
Maria Grazia Pia, INFN Genova
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Geometries
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Cuts in range (G3/G4)
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Visible energy in Si vs energy of the
incident electron: G3, G4, data
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Multiple scattering in thin layers
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Backscattering
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Low energy e.m. extensions
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High energy muons
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Geant4 hadronic physics
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Hadronic models, parameterised
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Photon evaporation
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Stopping pions
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Neutrons
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Atlas geometry
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CMS geometry and
magnetic field
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CMS e.m. calorimeter
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BaBar Geant4-based Simulation
BaBar Object-oriented Geant4-based Unified
Simulation (BOGUS)
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Integrated framework for Fast and Full simulation
Fast simulation available for public use since Feb. 99
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complete of fast reconstruction (downstream modules)
validation completed (B0 -> K+ pi-, B0 -> D*- l+ nu,
B0 -> J/Psi K0S, …)
Current version based on Geant4.0.1 (+additional
development patches)
Integrated in BaBar environment
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primary generators, reconstruction, OODB persistency
(materials & geometry description parameters, events)
parameters for materials and geometry shared with
reconstruction applications
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Examples of BaBar Geant4 geometries
EMC
Electro Magnetic Calorimeter
SVT
Silicon Vertex Tracker
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Borexino
 Geant4 components used to track photons
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geometry
physics processes pertinent to optical
photons (reflection, rifraction,
absorption etc.)
visualisation
 They have developed absorption and reemission
processes typical of Borexino scintillator
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Borexino
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Medical physics applications
A very active field!
 Studies for brachytherapy (IST Genova)
 Interface to CT for treatment planning
(Novara)
 Feasibility studies for new hadrotherapy
facilities (TERA)
 Magic Cube (INFN Torino)
etc...
Technology transfer from HEP to
other fields
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Low Energy processes
for medical applications
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Bragg peak
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Space applications
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Theoretical physics applications
Geant4 is used also by theorists
 Geant4 theoretical models for hadronic
physics to be used by theorists for further
theoretical developments and studies
(Quantum Molecular Dynamics, Heavy
Ions models etc.)
 All this is made possible by the OO design
of Geant4
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modular, flexible, extensible
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the physics is clearly exposed
Maria Grazia Pia, INFN Genova
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Performance
 Geant4 - Geant3.21 comparisons
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Realistic detector configurations
All results and plots available at
http://wwwinfo.cern.ch/asd/geant/geant4_public/gallery/
EMbenchmarks
 Benchmark in liquid Argon + Pb calorimeter
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At a comparable physics performance Geant4 is faster
than Geant3.21
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a factor >3 using exactly the same cuts
 by a factor >10 when Geant4 cuts are optimized,
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keeping the same physics performance
At comparable speed, Geant4 physics perfomance is far
superior to Geant3.21 one
 Benchmark in thin silicon layer
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Single volume, single material
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At a comparable physics performance Geant4 is 25%
faster than Geant3.21
 Many factors contribute to these results: design, more
powerful geometry navigation and tracking algorithms,
improved physics algorithms etc.
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Note: Geant3.21 run in its best optimized configuration for these tests
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An ambitious project
 What if the geometry to describe with Geant4 were
DNA and the process were mutagenesis?
 Study of radiation damage at the cellular and DNA
level in the space radiation environment
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ESA-sponsored project, in collaboration with INFN
INFN (Genova, Torino, Cosenza)
Istituto Nazionale per la Ricerca sul Cancro
Università del Piemonte Orientale (Novara)
ESA
CERN
 Multi-disciplinary Collaboration of
 astrophysicists and space scientists
 particle physicists
 medical physicists
 biologists
 physicians
 First phase of the project: User Requirements
Maria Grazia Pia, INFN Genova
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Conclusions
 Geant4 is used in a variety of applications
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HEP and nuclear physics experiments
astrophysics and astro-particle physics
space science studies
medical physics
etc.
 Several experiments are already in an advanced
stage of their Geant4-based applications
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complex geometry descriptions
comparisons with experimental data
production mode
 Various new tools offered by Geant4 respond to
essential needs of some user communities
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CAD interface
extensions of the physics processes covered
new physics
standard-compliant tools
etc.
Maria Grazia Pia, INFN Genova
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