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Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Architecture of collaborating frameworksArchitecture of collaborating frameworks
Simulation, Visualisation, User Interface and Analysis
G. Cosmo, R. Giannitrapani, F. Longo, R. Nartallo, P. Nieminen,
A. Pfeiffer, M.G. Pia, G. Santin
CERN - ESA - INFN (Ferrara, Genova, Trieste)
Budker Inst. of PhysicsIHEP ProtvinoMEPHI Moscow Pittsburg University
CHEP 2001 ConferenceBeijing, 3-7 September 2001
http://www.ge.infn.it/geant4/lowE/index.htmlhttp://www.ge.infn.it/geant4/lowE/index.html
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
UKDM, Boulby Mine
GLAST
ATLAS BaBar
A rigorous approach A rigorous approach to software to software engineeringengineering
Courtesy of L3
Courtesy of the Italian Nat. Inst. for Cancer
Research
E (MeV)
Photon attenuation
An extensive set of physics processes An extensive set of physics processes and models over a wide energy rangeand models over a wide energy range
High energy Low energy photons
particle in a cell
192Ir
highlights highlights
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Geant4 is a simulation Toolkit designed for a variety of applications
It adopts rigorous software engineering methodologies and is based on OO technology
It has been developed and is maintained by an international collaboration of > 100 scientists
- RD44 Collaboration (1994-98)
- Geant4 Collaboration
The code is publicly distributed from the WWW, together with ample documentation
1st production release: end 1998- 2 new releases/year since then
It provides a complete set of tools for all the typical domains of simulation
- run, event and track management
- geometry and materials
- tracking
- detector response
- PDG-compliant particle management
- user interface
- visualisation
- persistency
- physics processes
A wide domain of A wide domain of applications with applications with
a large user a large user community in many community in many
fieldsfields
HEP, astrophysics, nuclear physics, space sciences, medical physics, radiation studies
etc.
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Domain decomposition
hierarchical structure of
sub-domains
Geant4 architecture
Uni-directional flow of
dependencies
Software Engineering
plays a fundamental role in Geant4
User Requirements• formally collected• systematically updated• PSS-05 standard
Software Process• spiral iterative approach• regular assessments and improvements• monitored following the ISO 15504 model
Quality Assurance• commercial tools• code inspections• automatic checks of coding guidelines• testing procedures at unit and integration level• dedicated testing team
Object Oriented methods• OOAD• use of CASE tools
• essential for distributed parallel development• contribute to the transparency of physics
Use of Standards • de jure and de facto
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
GeometryGeometry
Borexino CMS
ATLAS
Chandra
XMM-Newton
Role: detailed detector description and efficient
navigation
CSGCSG (Constructed Solid Geometries)- simple solids
STEP extensionsSTEP extensions- polyhedra,, spheres, cylinders, cones, toroids, etc.
BREPSBREPS (Boundary REPresented Solids)- volumes defined by boundary surfaces- include solids defined by NURBS (Non-Uniform Rational B-Splines)
External tool for g3tog4 geometry conversion
Multiple representations(Same abstract interface)
CAD exchange: ISO STEP interface
Fields: of variable non-uniformity and differentiability
BaBar
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Guidelines for physicsGuidelines for physics
From the Minutes of LCB (LHCC Computing Board) meeting on 21 October, 1997:
Geant4 physics keeps evolvingGeant4 physics keeps evolvingwith attention to UR
facilitated by the OO technology
“It was noted that experiments have requirements for independent, alternative physics models. In Geant4 these models, differently from the concept of packages, allow the user to understand how the results are produced, and hence improve the physics validation. Geant4 is developed with a modular architecture and is the ideal framework where existing components are integrated and new models continue to be developed.”
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Geant4 PhysicsGeant4 Physics
OOD allows to implement or modify any physics process without changing other parts of the software
open to extension and open to extension and evolutionevolution
Tracking Tracking is independent from the physics processes
The generation of the final statefinal state is independent from the access and use of cross sections
Transparent access via virtual functions to- cross sectionscross sections (formulae, data sets etc.)
- modelsmodels underlying physics processes
An abundant set of electromagneticelectromagnetic and hadronic hadronic physics processes a variety of complementary and
alternative physics modelsphysics models for most processes
Use of public evaluated databasesevaluated databases
No tracking cuts, only production production thresholdsthresholds
- thresholds for producing secondaries are expressed in rangerange, universal for all media
- converted into energy for each particle and material
The transparency of the physics implementation contributes to The transparency of the physics implementation contributes to the validation of experimental physics resultsthe validation of experimental physics results
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Multiple scattering BremsstrahlungIonisationAnnihilationPhotoelectric effect Compton scattering Rayleigh effect conversione+e- pair productionSynchrotron radiationTransition radiationCherenkovRefractionReflectionAbsorptionScintillationFluorescenceAuger (in progress)
Electromagnetic physicsElectromagnetic physics
High energy extensionsHigh energy extensions- needed for LHC experiments, cosmic ray experiments…
Low energy extensionsLow energy extensions- fundamental for space and medical applications,
experiments, antimatter spectroscopy etc.
Alternative models for the same processAlternative models for the same process
energy loss
electrons and positrons , X-ray and optical photons muons charged hadrons ions
Comparable to Geant3 already in the 1st release (1997)
Further extensions (facilitated by the OO technology)
All obeying to the same abstract Process interface transparent to tracking
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Standard e.m. processesStandard e.m. processes
Multiple scatteringMultiple scattering- new model (by L. Urbán)- computes mean free path length and
lateral displacement
New energy loss algorithmNew energy loss algorithm- optimises the generation of rays near
boundaries
Variety of modelsVariety of models for ionisation and energy loss- including the PhotoAbsorption
Interaction model
Differential and Integral approachDifferential and Integral approach- for ionisation, Bremsstrahlung, positron
annihilation, energy loss and multiple scattering
Multiple scattering
6.56 MeV proton , 92.6 mm Si
J.Vincour and P.Bem Nucl.Instr.Meth. 148. (1978) 399
1 keV up to O(100 TeV)1 keV up to O(100 TeV)
Geant4Geant3data
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Low energy e.m. Low energy e.m. extensionsextensions
e,down to 250 eV (EGS4, ITS to 1 keV, Geant3 to 10 keV)
Fundamental for neutrino/dark matter
experiments, space and medical applications,
antimatter spectroscopy etc. Hadron and ion models
based on Ziegler and ICRU data and parameterisationsBarkas effect
(charge dependence)models for negative hadrons
0.01 0.1 1 100.01
0.1
1
10
100
1000
Geant4 LowEn NIST
/
(cm
2 /g
) in
iron
Photon Energy (MeV)
Based on EPDL97, EEDL and EADL evaluated data libraries
Bragg peak
shell effects
Photon attenuation
antiprotons
protons ions
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
MuonsMuons
1 keV up to 1000 PeV scale1 keV up to 1000 PeV scalesimulation of ultra-high energy and cosmic ray physics
High energy extensions based on theoretical models
Optical photonsOptical photons Production of optical photons in HEP detectors is
mainly due to Cherenkov effect and scintillation
Processes in Geant4:Processes in Geant4:- in-flight absorption- Rayleigh scattering- medium-boundary interactions
(reflection, refraction)
Photon entering a light concentrator CTF-Borexino
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Parameterised and data-driven hadronic models (1)Parameterised and data-driven hadronic models (1)
Based on experimental dataSome models originally from GHEISHA
- completely reengineered into OO design
- refined physics parameterisations
New parameterisations- pp, elastic differential cross section
- nN, total cross section
- pN, total cross section
- np, elastic differential cross section N, total cross section N, coherent elastic scattering
p elastic scattering on Hydrogen
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Other models are completely new, such as:
NeutronsCourtesy of CMS
nuclear deexcitation
absorption
Stopping
MeV
Energy
All worldwide existing databases used in neutron transport
Brond, CENDL, EFF, ENDFB, JEF, JENDL, MENDL etc.
neutrons
stopping particles: - , K- (relevant for PID detectors)
Isotope production
Parameterised and data-driven hadronic models (2)Parameterised and data-driven hadronic models (2)
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Theory-driven modelsTheory-driven models
Giant Dipole Resonance
Geant4data
Discrete transitions from ENSDF
Theoretical model for continuum Evaporation phase
Low energy range, pre-equilibrium, O(100 MeV)
Intermediate energy range, O(100 MeV) to O(5 GeV), intra-nuclear transport
High energy range, hadronic generator régime
Complementaryandalternativemodels
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Other componentsOther components
Materials- elements, isotopes, compounds,
chemical formulae
Particles- all PDG data
- and more, for specific Geant4 use, like ions
Hits & Digi- to describe detector response
Persistency- possibility to run in transient or
persistent mode
- no dependence on any specific persistency model
- persistency handled through abstract interfaces to ODBMS
Visualisation- Various drivers
- OpenGL, OpenInventor, X11, Postscript, DAWN, OPACS, VRML
User Interfaces- Command-line, Tcl/Tk, Tcl/Java,
batch+macros, OPACS, GAG, MOMO
- automatic code generation for geometry and materials
Interface to Event Generators- through ASCII file for generators
supporting /HEPEVT/
- abstract interface to Lund++
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Sector Shielding
Analysis Tool
CAD tool front-end
Delayed
radioactivity
General purpose source particle module
INTEGRAL and other science missions
Instrument design purposes Dose calculations
Particle source and spectrum
Geological surveys of asteroids
Modules for space applicationsModules for space applications
Low-energy Low-energy e.m. extensionse.m. extensions
Courtesy of P. Nieminen, ESA
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Courtesy of A. Pfeiffer, CERN
Example: AIDA & Analysis Tools
Similar approach:Similar approach: graphics (G)UI persistency etc.
Interface to external toolsInterface to external tools
No dependence
Minimize coupling of components
Java Analysis Studio
Lizard
Through abstract interfaces
AIDA
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
BaBar BaBar
Courtesy of D. Wright for the BaBar Collaboration
Preliminary
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Example of integrated Fast/Full Simulation applicationExample of integrated Fast/Full Simulation application
BaBar Object-oriented Geant4-based Unified Simulation (BOGUS) Integrated framework for Fast and Full simulation Fast simulation available for public use since February 1999 Integrated in BaBar environment
primary generators, reconstruction, OODB persistency parameters for materials and geometry shared with reconstruction applications
Courtesy of G. Cosmo for the BaBar Collaboration
Exploits Geant4 parameterisation (new feature)
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
ATLASATLAS300 GeV muons
20 GeV pions
TRT: Energy loss measured in ATLAS test beam compared to Geant3 and Geant4 simulations (PAI model)
Liquid Ar calorimeter
Fcal energy resolution
Muon detector
Preliminary
Courtesy of D. Barberis for ATLAS Collaboration
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
HARP with GEANT4HARP with GEANT4
Courtesy of P. Arce for the HARP Collaboration
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
T9 beam lineT9 beam line
Beam profile and composition at the HARP target
Simulation (10 GeV/c) Measurement
Beam spot width (mm) 3.27 approx. 4
Beam spot height (mm) 3.49 approx. 4
Beam spot position (mm) (0.33:0.86) (0.0:0.0)
Sophisticated geometry
Very non-uniform strong magnetic field
Primary target as a particle source
Courtesy of P. Arce for the HARP Collaboration
Preliminary
Crucial to have a precise absolute knowledge of the particle rate incident onto HARP target
Impossible to separate experimentally from in the beam with the accuracy required
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
GLAST (GLAST (ray telescope)ray telescope)
Preliminary
Courtesy of F. Longo and R. Giannitrapani, GLAST
GLAST
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Other astroparticle applicationsOther astroparticle applications
Courtesy of S. Magni, Borexino
Courtesy of A. Howard, UKDM
ZEPLIN IIIDark Matter, Boulby mine
Courtesy of R. Nartallo, ESA
XMM
X-ray telescope
Courtesy SOHO EIT
Cosmic rays,jovian electrons
Solar X-rays, e, p
low E physics fluorescence radioactivity neutrons space modules etc..
unique simulation capabilities:
Solar system explorations
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
Technology transferTechnology transfer
-40 -30 -20 -10 0 10 20 30 40-40
-30
-20
-10
0
10
20
30
40
Isodose 200% 150% 100% 75% 50% 25%
Dis
tanc
e a
lon
g lo
ng
itud
inal
axi
s (m
m)
Distance along transverse axis (mm)
Brachytherapy
Courtesy National Inst. for Cancer Research, Genova
Medical applications of Geant4: radiotherapy PET dosimetry etc.
Treatment planning
anisotropy
IsodosesCourtesy LIP & Portuguese Oncological Institute
Commercial treatment planning system
data
Histogram: Geant4
192Ir
Maria Grazia Pia, INFN Genova - EPS-HEP 2001
ConclusionsConclusions
Geant4 is a simulation Toolkit, providing advanced tools for all the domains of detector simulation
Geant4 is characterized by a rigorous approach to software engineering
Thanks to the OO technology, Geant4 is open to extension and evolution
An abundant set of physics processes is available, often with a variety of complementary and alternative physics models
Its areas of application span diverse fields: HEP and nuclear physics, astrophysics and space sciences, medical physics, radiation studies etc.
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