introduction to geant4 gunter folger, cern ep/sft michel maire, lapp/annecy on behalf of the geant4...

IntroductionIntroductiontoto

Geant4Geant4

Gunter Folger, CERN EP/SFT Gunter Folger, CERN EP/SFT

Michel Maire, LAPP/AnnecyMichel Maire, LAPP/Annecy

On behalf of the Geant4 On behalf of the Geant4 CollaborationCollaboration

30 September, 2003 30 September, 2003

Introduction to Geant4 - G.Folger/M.Maire, 30.September 2003, GridKa KarlsruheIntroduction to Geant4 - G.Folger/M.Maire, 30.September 2003, GridKa Karlsruhe 22

ContentsContents General introduction and brief historyGeneral introduction and brief history

Geant4 kernelGeant4 kernel

GeometryGeometry

PhysicsPhysics

GUI/VisualizationGUI/Visualization

User documention and examplesUser documention and examples

User support User support

Highlights of the new developmentsHighlights of the new developments

Highlights of user applications Highlights of user applications

Most of these slides are from tutorials of M.Asai and H.P.Wellisch Most of these slides are from tutorials of M.Asai and H.P.Wellisch

General introduction General introduction and brief historyand brief history


What is Geant4?What is Geant4? Geant4Geant4 is a toolkit for the is a toolkit for the simulationsimulation of the of the passagepassage of of

particlesparticles through through mattermatter..

Its application areas include high energy physics and nuclear Its application areas include high energy physics and nuclear

experiments, medical, accelerator and space physics studies.experiments, medical, accelerator and space physics studies.

Geant4 is the successor of GEANT3, the world-standard toolkit for HEP Geant4 is the successor of GEANT3, the world-standard toolkit for HEP

detector simulation.detector simulation.

Geant4 is one of the first successful attempt to re-design a major Geant4 is one of the first successful attempt to re-design a major

package of HEP software for the next generation of experiments using package of HEP software for the next generation of experiments using

an Object-Oriented environment. an Object-Oriented environment.

A variety of requirements also came from heavy ion physics, CP A variety of requirements also came from heavy ion physics, CP

violation physics, cosmic ray physics, astrophysics, space science and violation physics, cosmic ray physics, astrophysics, space science and

medical applications. medical applications.


Geant4 Geant4 CollaborationCollaboration

Collaborators also from non-member institutions, including

Budker Inst. of PhysicsIHEP Protvino

MEPHI Moscow Pittsburg University

Helsinki Inst. Ph.

PPARCUniv. Barcelona

HARP

Lebedev


Geant4 – Its history and futureGeant4 – Its history and future Dec ’94 - Project startDec ’94 - Project start

Apr ’97 - First alpha release Apr ’97 - First alpha release

Jul ’98 - First beta release Jul ’98 - First beta release

Dec ’98 - Geant4 0.0 releaseDec ’98 - Geant4 0.0 release

Jul ’99 - Geant4 0.1 releaseJul ’99 - Geant4 0.1 release

……

Jun ’03 - Geant4 5.2 releaseJun ’03 - Geant4 5.2 release

Dec ’03 - Geant4 6.0 release (planned)Dec ’03 - Geant4 6.0 release (planned)

We currently provide two to three public releases and We currently provide two to three public releases and

monthly beta releases in between public releases every monthly beta releases in between public releases every

year.year.


Flexibility of Geant4Flexibility of Geant4 In order to meet wide variety of requirements from various In order to meet wide variety of requirements from various

application fields, a large degree of functionality and flexibility application fields, a large degree of functionality and flexibility

are provided. are provided.

Geant4 has many types of geometrical descriptions to describe Geant4 has many types of geometrical descriptions to describe

most complicated and realistic geometries most complicated and realistic geometries

CSG, BREP, BooleanCSG, BREP, Boolean

STEP compliant STEP compliant

XML interfaceXML interface

Everything is open to the user Everything is open to the user

Choice of physics processes/modelsChoice of physics processes/models

Choice of GUI/Visualization/persistency/histogramming Choice of GUI/Visualization/persistency/histogramming

technologiestechnologies


Physics in Geant4Physics in Geant4 It is rather unrealistic to develop a uniform physics model to It is rather unrealistic to develop a uniform physics model to

cover wide variety of particles and/or wide energy range.cover wide variety of particles and/or wide energy range. Much wider coverage of physics comes from mixture of theory-Much wider coverage of physics comes from mixture of theory-

driven, parameterized, or data driven approaches. Thanks to driven, parameterized, or data driven approaches. Thanks to polymorphism mechanism, both cross-sections and models polymorphism mechanism, both cross-sections and models (final state generation) can be combined in arbitrary manners (final state generation) can be combined in arbitrary manners into one particular process.into one particular process. Standard EM processesStandard EM processes Low energy EM processesLow energy EM processes Hadronic processesHadronic processes Photon/lepton-hadron processesPhoton/lepton-hadron processes Optical photon processesOptical photon processes Decay processesDecay processes Shower parameterizationShower parameterization Event biasing technique Event biasing technique


Physics in Geant4Physics in Geant4 Each cross-section table or physics model (final state generation) Each cross-section table or physics model (final state generation)

has its own applicable energy range. Combining more than one has its own applicable energy range. Combining more than one

tables / models, one physics process can have enough coverage tables / models, one physics process can have enough coverage

of energy range for wide variety of simulation applications.of energy range for wide variety of simulation applications.

Geant4 provides sets of alternative physics models so that the Geant4 provides sets of alternative physics models so that the

user can freely choose appropriate models according to the type user can freely choose appropriate models according to the type

of his/her application.of his/her application.

Several individual universities / physicists groups are contributing Several individual universities / physicists groups are contributing

their physics models to Geant4. Given the modular structure of their physics models to Geant4. Given the modular structure of

Geant4, developers of each physics model are well recognized Geant4, developers of each physics model are well recognized

and credited.and credited.

Geant4 kernelGeant4 kernel


Geant4 kernelGeant4 kernel Geant4 consists of 17 categories.Geant4 consists of 17 categories.

Independently developed and Independently developed and

maintained by WG(s) responsible maintained by WG(s) responsible

to each category.to each category.

Interfaces between categories Interfaces between categories

(e.g. top level design) are (e.g. top level design) are

maintained by the global maintained by the global

architecture WG.architecture WG.

Geant4 KernelGeant4 Kernel

Handles run, event, track, step, Handles run, event, track, step,

hit, trajectory.hit, trajectory.

Provides frameworks of Provides frameworks of

geometrical representation and geometrical representation and

physics processes.physics processes.

Geant4

ReadoutVisuali zation

Persis tency

Run

Event

Inter faces

Tracking

Digits + Hits

Processes

Track

Geometry Particle

Graphic _reps

Material

Intercoms

Global


Tracking and processesTracking and processes Geant4 tracking is general. Geant4 tracking is general.

It is independent to It is independent to

the particle type the particle type

the physics processthe physics process

It gives the chance to all processes It gives the chance to all processes

To contribute to determining the step lengthTo contribute to determining the step length

To contribute any possible changes in physical To contribute any possible changes in physical

quantities of the trackquantities of the track

To generate secondary particlesTo generate secondary particles

To suggest changes in the state of the trackTo suggest changes in the state of the track

e.g. to suspend, postpone or kill it.e.g. to suspend, postpone or kill it.


Processes in Geant4Processes in Geant4 In Geant4, particle transportation is a process as well, by which In Geant4, particle transportation is a process as well, by which

a particle interacts with geometrical volume boundaries and a particle interacts with geometrical volume boundaries and

field of any kind.field of any kind.

Each particle has its own list of applicable processes. At each Each particle has its own list of applicable processes. At each

step, all processes listed are invoked to get proposed physical step, all processes listed are invoked to get proposed physical

interaction lengths.interaction lengths.

The process which requires the shortest interaction length (in The process which requires the shortest interaction length (in

space-time) limits the step. space-time) limits the step.


Track in Geant4Track in Geant4 Track is a snapshot of a particle.Track is a snapshot of a particle.

It has only position and physical quantities of current It has only position and physical quantities of current

instance.instance. Step is a “delta” information to a track.Step is a “delta” information to a track.

Track is not a collection of steps.Track is not a collection of steps. Track is deleted whenTrack is deleted when

it goes out of the world volumeit goes out of the world volume it disappears (e.g. decay)it disappears (e.g. decay) it goes down to zero kinetic energy and no “AtRest” it goes down to zero kinetic energy and no “AtRest”

additional process is requiredadditional process is required the user decides to kill itthe user decides to kill it

No track object persists at the end of event.No track object persists at the end of event. For the record of track, use trajectory class objects.For the record of track, use trajectory class objects.


Step in Geant4Step in Geant4 Step has two points and also “delta” information of a particle Step has two points and also “delta” information of a particle

(energy loss on the step, time-of-flight spent by the step, etc.).(energy loss on the step, time-of-flight spent by the step, etc.).

Each point knows the volume (and material). In case a step is Each point knows the volume (and material). In case a step is

limited by a volume boundary, the end point physically stands limited by a volume boundary, the end point physically stands

on the boundary, and it logically belongs to the next volume.on the boundary, and it logically belongs to the next volume.

Because one step knows materials of two volumes, Because one step knows materials of two volumes,

boundary processes such as transition radiation or boundary processes such as transition radiation or

refraction can be simulated.refraction can be simulated.

Begin of step pointEnd of step point

Step

Boundary


CutsCuts in Geant4 in Geant4

A Cut in Geant4 is a A Cut in Geant4 is a production thresholdproduction threshold Only for physics processes that have infrared divergenceOnly for physics processes that have infrared divergence Not tracking cut, which does not exist in Geant4Not tracking cut, which does not exist in Geant4

Energy threshold must be determined below which generated Energy threshold must be determined below which generated secondaries are replaced by continuous losssecondaries are replaced by continuous loss tracktrack primary down to zero rangeprimary down to zero range Create secondaries only above specified threshold, and add Create secondaries only above specified threshold, and add

to continuous loss of primary for secondaries of less to continuous loss of primary for secondaries of less energeticenergetic


StackStack Track is a class object, thus it is easy Track is a class object, thus it is easy

to treat suspending or postponing to treat suspending or postponing

tracks. For example,tracks. For example, Suspend tracks at the entrance of Suspend tracks at the entrance of

calorimeter, i.e. simulate all tracks calorimeter, i.e. simulate all tracks

in tracking region before in tracking region before

generating showers.generating showers. Suspend a “looper” track after Suspend a “looper” track after

certain time and postpone it to certain time and postpone it to

next event.next event. Prioritized tracking without Prioritized tracking without

performance costperformance cost Well-thought prioritization/abortion of Well-thought prioritization/abortion of

tracks/events makes entire simulation tracks/events makes entire simulation

process much more efficient.process much more efficient.


Unit systemUnit system Internal unit system used in Geant4 is completely hidden not only Internal unit system used in Geant4 is completely hidden not only

from user’s code but also from Geant4 source code from user’s code but also from Geant4 source code

implementation.implementation. Each hard-coded number must be multiplied by its proper unit.Each hard-coded number must be multiplied by its proper unit.

radius = 10.0 * cm;radius = 10.0 * cm;

kineticE = 1.0 * GeV;kineticE = 1.0 * GeV;

To get a number, it must be divided by a proper unit.To get a number, it must be divided by a proper unit.

G4cout << eDep / MeV << “ [MeV]” << G4endl;G4cout << eDep / MeV << “ [MeV]” << G4endl;

Or Or

G4cout << G4BestUnit(eDep, “Energy”) << G4endl;G4cout << G4BestUnit(eDep, “Energy”) << G4endl;

Most of commonly used units are provided and user can add Most of commonly used units are provided and user can add

his/her own units.his/her own units. By this explicit unit system, source code becomes more readable By this explicit unit system, source code becomes more readable

and importing / exporting physical quantities becomes and importing / exporting physical quantities becomes

straightforwardstraightforward

GeometryGeometry


VolumeVolume Three conceptual layers Three conceptual layers

G4VSolid -- G4VSolid -- shape, sizeshape, size G4LogicalVolume -- G4LogicalVolume -- daughter physical volumes, daughter physical volumes,

material, sensitivity, user limits, etc.material, sensitivity, user limits, etc. G4VPhysicalVolume -- G4VPhysicalVolume -- position, rotationposition, rotation

Hierarchical three layers of geometry description allows maximum Hierarchical three layers of geometry description allows maximum reuse of information to minimize the use of memory space.reuse of information to minimize the use of memory space.

G4Box

G4Tubs

G4VSolid G4VPhysicalVolume

G4Material

G4VSensitiveDetector

G4PVPlacement

G4PVParameterised

G4VisAttributes

G4LogicalVolume


SolidSolid Geant4 geometry module supports variety of Geant4 geometry module supports variety of

representations of shapes.representations of shapes. CSG (Constructed Solid Geometry) solidsCSG (Constructed Solid Geometry) solids

G4Box, G4Tubs, G4Cons, G4Trd, …G4Box, G4Tubs, G4Cons, G4Trd, … Analogous to simple GEANT3 CSG Analogous to simple GEANT3 CSG

solidssolids Specific solids (CSG like)Specific solids (CSG like)

G4Polycone, G4Polyhedra, G4Hype, …G4Polycone, G4Polyhedra, G4Hype, … BREP (Boundary REPresented) solidsBREP (Boundary REPresented) solids

G4BREPSolidPolycone, G4BREPSolidPolycone, G4BSplineSurface, …G4BSplineSurface, …

Any order surfaceAny order surface Boolean solidsBoolean solids

G4UnionSolid, G4SubtractionSolid, …G4UnionSolid, G4SubtractionSolid, …


Physical volumePhysical volume G4PVPlacement 1 Placement = One VolumeG4PVPlacement 1 Placement = One Volume

A volume instance positioned once in its mother volumeA volume instance positioned once in its mother volume G4PVParameterised 1 Parameterized = Many VolumesG4PVParameterised 1 Parameterized = Many Volumes

Parameterized by the copy numberParameterized by the copy number Shape, size, material, position and rotation can be Shape, size, material, position and rotation can be

parameterized, by implementing a concrete class of parameterized, by implementing a concrete class of G4VPVParameterisation.G4VPVParameterisation.

Reduction of memory consumption Reduction of memory consumption Currently: parameterization can be used only for volumes that either Currently: parameterization can be used only for volumes that either

a) have no further daughters, or a) have no further daughters, or b) are identical in size & shape.b) are identical in size & shape.

G4PVReplica 1 Replica = Many VolumesG4PVReplica 1 Replica = Many Volumes Slicing a volume into smaller pieces (if it has a symmetry)Slicing a volume into smaller pieces (if it has a symmetry)

G4ReflectionFactory 1 Placement = a set of VolumesG4ReflectionFactory 1 Placement = a set of Volumes generating placements of a volume and its reflected volumegenerating placements of a volume and its reflected volume Useful typically for end-cap calorimeterUseful typically for end-cap calorimeter

G4AssemblyVolume 1 Placement = a set of PlacementsG4AssemblyVolume 1 Placement = a set of Placements Position a group of volumesPosition a group of volumes


Smart voxelizationSmart voxelization User’s geometry is automatically optimized to most suitable to the User’s geometry is automatically optimized to most suitable to the

navigation. - "Voxelization"navigation. - "Voxelization" For each mother volume, one-dimensional virtual division is For each mother volume, one-dimensional virtual division is

performed.performed. Subdivisions (slices) containing same volumes are gathered into Subdivisions (slices) containing same volumes are gathered into

one.one. Additional division again using second and/or third Cartesian axes, if Additional division again using second and/or third Cartesian axes, if

needed.needed. "Smart voxels""Smart voxels" are computed at initialisation time are computed at initialisation time

When the detector geometry is When the detector geometry is closedclosed Does not require large memory or computing resourcesDoes not require large memory or computing resources At tracking time, searching is done in a hierarchy of virtual divisionsAt tracking time, searching is done in a hierarchy of virtual divisions


Field integrationField integration In order to propagate a particle inside a field (e.g. magnetic, In order to propagate a particle inside a field (e.g. magnetic,

electric or both), we solve the equation of motion of the electric or both), we solve the equation of motion of the particle in the field. particle in the field.

We use a Runge-Kutta method for the integration of the We use a Runge-Kutta method for the integration of the ordinary differential equations of motionordinary differential equations of motion Several Runge-Kutta ‘steppers’ are availableSeveral Runge-Kutta ‘steppers’ are available

In specific cases other solvers can also be used In specific cases other solvers can also be used Using the method to calculate the track's motion in a field, Using the method to calculate the track's motion in a field,

Geant4 breaks up this curved path into linear chord segmentsGeant4 breaks up this curved path into linear chord segments We determine the chord segments so that they closely We determine the chord segments so that they closely

approximate the curved pathapproximate the curved path

‘Tracking’ StepChords

Real Trajectory


Geometry checking toolsGeometry checking tools Geant4 assumes the geometry is well Geant4 assumes the geometry is well

defineddefined overlapping volumes generates overlapping volumes generates

inconsistenciesinconsistencies The problem of detecting overlaps in a The problem of detecting overlaps in a

generic geometry setup is complex.generic geometry setup is complex. Utilities are provided for detecting Utilities are provided for detecting

wrong positioningwrong positioning Graphical toolsGraphical tools Kernel run-time commandsKernel run-time commands External OLAP application (CMS)External OLAP application (CMS)


Material constructionMaterial construction There are three ways to construct materials in Geant4There are three ways to construct materials in Geant4

From it’s isotopic compositionFrom it’s isotopic composition From it’s elementsFrom it’s elements As an effective material (Aeff, Zeff)As an effective material (Aeff, Zeff)

PhysicsPhysics


What is tracked in What is tracked in GGEANT4EANT4 ? ?

G4Track

G4ParticleDefinition

G4DynamicParticle

G4ProcessManager

• Propagated by the tracking,• Snapshot of the particle state and location.

• Momentum, pre-assigned decay…

• The « particle type »: G4Electron, G4PionPlus…

• « Hangs » the physics sensitivity;

• The physics processes;

Process_2

Process_1

Process_3

• The classes involved in the building the « physics list » are:• The G4ParticleDefinition

concrete classes;• The G4ProcessManager;• The processes;


– PostStep actions:• Compton, pair production, most hadronic interactions, …• But also ionisation, bremstrahlung, …

The process tracking interfaceThe process tracking interface..

There are three situations, where <tracking> may want to ask information There are three situations, where <tracking> may want to ask information from <process>:from <process>:

– AlongStep:• To describe ‘continuous’ interactions, occuring along the path of the particle, like ionisation, cherenkov, bremsstrahlung,…

– AtRest:• Decay, e+ annihilation …

AlongStep

PostStep


A process will implement A process will implement any combinationany combination of the three of the three AtRestAtRest, , AlongStepAlongStep and and PostStepPostStep actions: actions:

Eg: decay = AtRest + PostStepEg: decay = AtRest + PostStep Each action defines Each action defines two methodstwo methods::

– GetPhysicalInteractionLength():• Used to limit the step size:

– because the process « triggers » an interaction, a decay, geometry boundary, a user’s limit …

– DoIt():• Implements the actual action to be applied on the track;• Typically final state generation.

The process tracking interfaceThe process tracking interface..


G4VProcess & G4ProcessManagerG4VProcess & G4ProcessManager

Really, the Really, the G4ProcessManagerG4ProcessManager has has three vectors of actionsthree vectors of actions:: One for the One for the AtRestAtRest methods of the particle;methods of the particle; One for theOne for the AlongStepAlongStep ones; ones; And one for theAnd one for the PostStepPostStep actions.actions.

It is those vectors the user sets up in the physics list and which It is those vectors the user sets up in the physics list and which are used by the tracking.are used by the tracking.


Built-in physics processesBuilt-in physics processes Physics processes describe how particles interact with Physics processes describe how particles interact with

material or volume itself. material or volume itself.

There are 7 major process categories in Geant4There are 7 major process categories in Geant4

ElectromagneticElectromagnetic

HadronicHadronic

Photolepton_hadronPhotolepton_hadron

DecayDecay

OpticalOptical

TransportationTransportation

ParameterizationParameterization


Built-in physics processesBuilt-in physics processes It is the user’s responsibility to choose physics processes, models It is the user’s responsibility to choose physics processes, models

and/or cross-section tables.and/or cross-section tables.

Geant4 kernel provides no default. Even for the transportation, Geant4 kernel provides no default. Even for the transportation,

the user has to assign it to all particles.the user has to assign it to all particles.

Geant4 provides lots of utility methods and reusable examples.Geant4 provides lots of utility methods and reusable examples.

We provide physics lists for many application areas for We provide physics lists for many application areas for

hadronicshadronics

There are some alternative processes in our distribution. Thanks There are some alternative processes in our distribution. Thanks

to polymorphism, it is quite easy to replace one to polymorphism, it is quite easy to replace one

process/model/cross-section to another. process/model/cross-section to another.

The user can easily plug-in his/her own particular The user can easily plug-in his/her own particular

process/model/cross-section without touching to any other part.process/model/cross-section without touching to any other part.


Electromagnetic processesElectromagnetic processes We have two sets of electromagnetic processes for We have two sets of electromagnetic processes for

photons, photons,

electrons/positrons, electrons/positrons,

muons, muons,

hadrons,hadrons,

and some ionsand some ions

Standard EM package ignores the binding energy of Standard EM package ignores the binding energy of

electron to an atom, while Low Energy EM package takes electron to an atom, while Low Energy EM package takes

into account.into account.


Hadronic and Photolepton-hadron Hadronic and Photolepton-hadron processesprocesses

Each hadronic process may have one or moreEach hadronic process may have one or more

cross section data sets, and cross section data sets, and

final state production models final state production models

associated with it. Each model has its own energy range of associated with it. Each model has its own energy range of

applicability.applicability.

The term “data set” is meant in a broad sense to be an object that The term “data set” is meant in a broad sense to be an object that

encapsulates methods and data for calculating total cross sections.encapsulates methods and data for calculating total cross sections.

The term “model” is meant in a broad sense to be an object that The term “model” is meant in a broad sense to be an object that

encapsulates methods and data for calculating final state products.encapsulates methods and data for calculating final state products.


Hadronic vs. electromagnetic Hadronic vs. electromagnetic processesprocesses

In EM physics (mostly): In EM physics (mostly): 1 process = 1 model and 1 cross-section.1 process = 1 model and 1 cross-section.

In hadronic physics (mostly): In hadronic physics (mostly): 1 process = an assembly and selection of many cross-sections data-sets, 1 process = an assembly and selection of many cross-sections data-sets,

models, production codes, model components, sub-assemblies, options. models, production codes, model components, sub-assemblies, options. Default cross-section are provided for each process.Default cross-section are provided for each process. You decide in the physics list, what exactly you use.You decide in the physics list, what exactly you use. Mix, match, assemble.Mix, match, assemble.


What cross-sections and What cross-sections and models are available?models are available?

Default covers all possible situations for hadron interactions.Default covers all possible situations for hadron interactions. Carried forward from geant3.21.Carried forward from geant3.21.

Different kinds of cross-section data setsDifferent kinds of cross-section data sets Some are parametrizations,Some are parametrizations, Some are theory,Some are theory, Some read and use large databases.Some read and use large databases.


Final state generatorsFinal state generators Three categories of modeling approachesThree categories of modeling approaches

Parametrization driven modelingParametrization driven modeling Data driven modelingData driven modeling Theory driven modelingTheory driven modeling


Parameterisation driven Parameterisation driven modelsmodels

Two domains:Two domains: high energy inelastic (Aachen, CERN)high energy inelastic (Aachen, CERN) low energy inelastic, elastic, fission, capture (TRIUMF, UBC, low energy inelastic, elastic, fission, capture (TRIUMF, UBC,

CERN)CERN)

Stopping particlesStopping particles base line (TRIUMF, CHAOS)base line (TRIUMF, CHAOS) mu- (TRIUMF, FIDUNA)mu- (TRIUMF, FIDUNA) pi- (INFN, CERN, TRIUMF) pi- (INFN, CERN, TRIUMF) K- (Crystal Barrel, TRIUMF)K- (Crystal Barrel, TRIUMF) anti-protons (JLAB, CERN)anti-protons (JLAB, CERN) Electromagnetic transitions of the exotic atom prior to capture; Electromagnetic transitions of the exotic atom prior to capture;

effects of atomic binding. (Novosibirsk, ESA)effects of atomic binding. (Novosibirsk, ESA)


Data driven models Data driven models

Low energy neutron transport (neutron_hp),Low energy neutron transport (neutron_hp), Radioactive decay (DERA, ESA)Radioactive decay (DERA, ESA) photon evaporation (INFN)photon evaporation (INFN) elastic scattering (TRIUMF, U.Alberta, CERN)elastic scattering (TRIUMF, U.Alberta, CERN) internal conversion (ESA), internal conversion (ESA), etc..etc..


Theory driven modelsTheory driven models

Ultra-high energy modelsUltra-high energy models Parton transport model (U.Frankfurt, in discussion)Parton transport model (U.Frankfurt, in discussion)

High energy modelsHigh energy models ‘‘Fritjof’ type string model (CERN)Fritjof’ type string model (CERN) Quark gluon String (CERN)Quark gluon String (CERN) Pythia(7) interface (Lund, CERN)Pythia(7) interface (Lund, CERN)

Intra-nuclear transport models (or replacements)Intra-nuclear transport models (or replacements) Hadronic cascade+pre-equilibrium (HIP, CERN)Hadronic cascade+pre-equilibrium (HIP, CERN) Binary and Bertini cascades (HIP, CERN, Novosibirsk, SLAC)Binary and Bertini cascades (HIP, CERN, Novosibirsk, SLAC) QMD type models (CERN, Inst.Th.Phys. Frankfurt)QMD type models (CERN, Inst.Th.Phys. Frankfurt) Chiral invariant phase-space decay (JLAB, CERN, ITEP)Chiral invariant phase-space decay (JLAB, CERN, ITEP) Partial Mars rewrite (Kyoto, Uvic, in collaboration with FNAL)Partial Mars rewrite (Kyoto, Uvic, in collaboration with FNAL)

De-excitationDe-excitation Evaporation, fission, multi-fragmentation, fermi-break-up (CMS)Evaporation, fission, multi-fragmentation, fermi-break-up (CMS)


A not totally correct hadronic model summaryA not totally correct hadronic model summary

1 MeV 10 MeV 100 MeV 1 GeV 10 GeV 100 GeV 1 TeV 10 TeV 100 TeV

CHIPS I

Absorption at restK, p-bar, n-bar

CHIPS (gamma)

QGS string

FTF string

HEP

LEP

mars

Binary cascade

Bertini cascadeRad. Dec.

conversionPhot, ev.

multifragFermi

PrecompoundFission

Evap

Neutron_hp

(I fore sure left off something, like G4LElastic)

LEpp, np


In hadronic physics In hadronic physics the problem was complexitythe problem was complexity

It takes 5 levels of implementation framework in geant4 to implement It takes 5 levels of implementation framework in geant4 to implement hadronics.hadronics.

These, and the models implementing them, are used to assemble the hadronic These, and the models implementing them, are used to assemble the hadronic physics for the simulation engine.physics for the simulation engine.

The number of options is quite large.The number of options is quite large. Each comes with trade-offs in descriptive power and performance.Each comes with trade-offs in descriptive power and performance. There are 25 particle species to be tracked, that need complete and consistent There are 25 particle species to be tracked, that need complete and consistent

physics.physics.


The recommended procedureThe recommended procedure

Start by trying the provided physics lists.Start by trying the provided physics lists. It makes it such that results by different groups can be compared.It makes it such that results by different groups can be compared. You will profit from validation and verification done by others.You will profit from validation and verification done by others. It makes your (and my) life much easier.It makes your (and my) life much easier.


Use case packages of Physics Use case packages of Physics ListsLists

LCG simulation project.LCG simulation project. HEP calorimetry. HEP calorimetry. HEP trackers. HEP trackers. 'Average' collider detector 'Average' collider detector Low energy dosimetric Low energy dosimetric

applicationsapplicationswith neutrons with neutrons

low energy nucleon penetration low energy nucleon penetration shielding shielding

linear collider neutron fluxeslinear collider neutron fluxes high energy penetration high energy penetration

shieldingshielding medical and other life-saving medical and other life-saving

neutron applicationsneutron applications

low energy dosimetric low energy dosimetric applications applications

high energy production targetshigh energy production targets e.g. 400GeV protons on C or e.g. 400GeV protons on C or

BeBe medium energy production medium energy production

targetstargets e.g. 15-50 GeV p on light e.g. 15-50 GeV p on light

targetstargets LHC neutron fluxes LHC neutron fluxes Air shower applications (still Air shower applications (still

working on this)working on this) low background experimentslow background experiments

http://cmsdoc.cern.ch/~hpw/GHAD/HomePage












DecayDecay A decay table is associated to the definition of each particle typeA decay table is associated to the definition of each particle type

A track can have a decay channel. If it has, it exactly decays A track can have a decay channel. If it has, it exactly decays

through this channel without randomizing by the decay ratio.through this channel without randomizing by the decay ratio.

This allows the user to import decay chains generated by This allows the user to import decay chains generated by

physics generators such as Pythia, and rely on Geant4 physics generators such as Pythia, and rely on Geant4

tracking for such unstable particles.tracking for such unstable particles.

Primary particle list

B0

K0L…

B0 G4Track

K0L…

“predefined”decay channel


Optical processesOptical processes Geant4 has a particle named “Optical Photon”, which is Geant4 has a particle named “Optical Photon”, which is

different from gamma. It interacts by optical processes.different from gamma. It interacts by optical processes. Optical photons are generated if one or more of following Optical photons are generated if one or more of following

processes are activated.processes are activated. Cherenkov radiationCherenkov radiation ScintillationScintillation

Optical processesOptical processes AbsorptionAbsorption Rayleigh scatteringRayleigh scattering Boundary Processes (reflection, refraction)Boundary Processes (reflection, refraction)

Optical properties, e.g. dielectric coefficient and surface Optical properties, e.g. dielectric coefficient and surface

smoothness, can be set to a volume.smoothness, can be set to a volume.


Shower parameterization Shower parameterization frameworkframework

Geant4 includes a built-in framework for shower Geant4 includes a built-in framework for shower

parameterization scheme. Currently, the user has to concrete parameterization scheme. Currently, the user has to concrete

his/her own parameterization assigned to a logical volume, his/her own parameterization assigned to a logical volume,

which is then called as an “envelop”.which is then called as an “envelop”. Regardless of the existence of granular daughter geometry, Regardless of the existence of granular daughter geometry,

a particle comes into the envelop can be fully treated by a particle comes into the envelop can be fully treated by

the shower parameterization process. the shower parameterization process. The user still have a dynamic choice to take his/her The user still have a dynamic choice to take his/her

parameterization or to follow the ordinary tracking in the parameterization or to follow the ordinary tracking in the

granular geometry.granular geometry. The shower parameterization process can directly contact The shower parameterization process can directly contact

to a sensitive detector associating to the volume to to a sensitive detector associating to the volume to

produce more than one distributed hits.produce more than one distributed hits.

Graphical User InterfacesGraphical User Interfacesand Visualizationand Visualization


IntercomsIntercoms ““Intercoms” category handles the framework mechanism of Intercoms” category handles the framework mechanism of

defining and delivering commands.defining and delivering commands.

Exportable to any other applicationExportable to any other application

Independent to other Geant4 categoriesIndependent to other Geant4 categories

Powerful type and range checkingPowerful type and range checking

Range description can be defined by C++ syntaxRange description can be defined by C++ syntax

aCmd->SetRange(“x>0. && y>0.”);aCmd->SetRange(“x>0. && y>0.”); Dynamic command definition / activationDynamic command definition / activation

Commands can be hard-coded or issued by (G)UI.Commands can be hard-coded or issued by (G)UI.

Macro fileMacro file

Recursive variable definitionRecursive variable definition

Loop with counter variableLoop with counter variable


(Graphical) User Interfaces(Graphical) User Interfaces Geant4 kernel is independent of any specific GUI technology.Geant4 kernel is independent of any specific GUI technology. Geant4 provides several alternative (G)UIs or interfaces to Geant4 provides several alternative (G)UIs or interfaces to

external GUI packages. The user can choose one or more of external GUI packages. The user can choose one or more of them according to his computer environment / need.them according to his computer environment / need. Character terminal (csh and tcsh(bash)-like terminal) Character terminal (csh and tcsh(bash)-like terminal) Xm, Xaw, Win32, variations of the upper terminals by using Xm, Xaw, Win32, variations of the upper terminals by using

a Motif, Athena or Windows widget to retrieve commands a Motif, Athena or Windows widget to retrieve commands GAG, a fully Graphical User Interface and its extension GAG, a fully Graphical User Interface and its extension

GainServer of the client/server type GainServer of the client/server type OPACS, an OPACS/Wo widget manager implementation in OPACS, an OPACS/Wo widget manager implementation in

conjunction with the OPACS visualization system. conjunction with the OPACS visualization system. JAG, an interface to JAS (Java Analysis Studio)JAG, an interface to JAS (Java Analysis Studio) User can connect his/her own GUI to Geant4User can connect his/her own GUI to Geant4


VisualizationVisualization Geant4 kernel is independent to any specific visualization Geant4 kernel is independent to any specific visualization

technology.technology. Geant4 provides several alternative visualization drivers or Geant4 provides several alternative visualization drivers or

interfaces to external visualization drivers. The user can choose interfaces to external visualization drivers. The user can choose one or more of them according to computer environment / need.one or more of them according to computer environment / need. OpenGL viewers OpenGL viewers FukuiRenderer (DAWN)FukuiRenderer (DAWN) VRML builderVRML builder WIREDWIRED Wo, Xo (OPACS)Wo, Xo (OPACS) OpenInventorX (OIX)OpenInventorX (OIX) RayTracerRayTracer User can connect his/her own visualization driver to Geant4User can connect his/her own visualization driver to Geant4

Some example figures are given with introduction of users Some example figures are given with introduction of users applications in this presentationapplications in this presentation

User documentsUser documentsandand

examplesexamples


Documents for usersDocuments for users One introductory guide and five user manualsOne introductory guide and five user manuals

http://cern.ch/geant4/G4UsersDocuments/ http://cern.ch/geant4/G4UsersDocuments/ Overview/html/index.htmlOverview/html/index.html

Installation guideInstallation guide User's guide for application developersUser's guide for application developers

For a user who develops a simulation application using For a user who develops a simulation application using Geant4 Geant4

User's guide for toolkit developersUser's guide for toolkit developers For a user who develops a module which alternates or For a user who develops a module which alternates or

enhances some of geant4 functionalities enhances some of geant4 functionalities Physics reference manualPhysics reference manual

Detailed description of each physics process with information Detailed description of each physics process with information of referencesof references

Software reference manualSoftware reference manual LXR source code browser maintained by TRIUMF and KEK.LXR source code browser maintained by TRIUMF and KEK. Materials of past tutorials / presentations, HyperNews and Web Materials of past tutorials / presentations, HyperNews and Web

pages maintained by developers available via Geant4 Web page.pages maintained by developers available via Geant4 Web page. "Geant4 general paper" - NIM A 506."Geant4 general paper" - NIM A 506.


ExamplesExamples Along the code releases, Geant4 provides examples helping Along the code releases, Geant4 provides examples helping

users to understand functionalities of Geant4users to understand functionalities of Geant4

Examples serve as "skeletons" of user's application.Examples serve as "skeletons" of user's application.

Three levels of examplesThree levels of examples

Novice examples : Novice examples :

Demonstrate most basic featuresDemonstrate most basic features

Extended examples : Extended examples :

Highlight some functionalities / use-cases in detailHighlight some functionalities / use-cases in detail

Some examples require external package(s)Some examples require external package(s)

Advanced examples :Advanced examples :

Most realistic applicationsMost realistic applications

User's contributionsUser's contributions

User SupportUser Support


User SupportUser Support Geant4 Collaboration offers extensive user supports.Geant4 Collaboration offers extensive user supports.

Users workshopsUsers workshops

Tutorial coursesTutorial courses

HyperNews and mailing listHyperNews and mailing list

Problem reporting system Problem reporting system

Requirements tracking systemRequirements tracking system

Daily “private” communicationsDaily “private” communications

New: Technical ForumNew: Technical Forum

First one at TRIUMF, 5.September 2003First one at TRIUMF, 5.September 2003

Next one at CERN, 7.October 2003 Next one at CERN, 7.October 2003


Geant4 users workshopGeant4 users workshop Users workshops were held or are going to be held hosted by Users workshops were held or are going to be held hosted by

several institutes for various user communities.several institutes for various user communities.

KEK - Dec.2000, Jul.2001, Mar.2002, Jul.2002, Mar.2003, KEK - Dec.2000, Jul.2001, Mar.2002, Jul.2002, Mar.2003,

Jul.2003Jul.2003

SLAC - Feb.2002SLAC - Feb.2002

Spain (supported by INFN) - Jul.2002Spain (supported by INFN) - Jul.2002

CERN - Nov.2002CERN - Nov.2002

ESA - Jan.2003, Jan.2004 (planned) ESA - Jan.2003, Jan.2004 (planned)

dedicated to space-related usersdedicated to space-related users

Helsinki - Oct.2003Helsinki - Oct.2003

Local workshops of one or two days were held or are Local workshops of one or two days were held or are

planned at several places.planned at several places.


Geant4 tutorials / lecturesGeant4 tutorials / lectures In addition to the users workshops, many tutorial courses and In addition to the users workshops, many tutorial courses and

lectures with some discussion time slots were held for various lectures with some discussion time slots were held for various user communities.user communities. CERN School of ComputingCERN School of Computing Italian National School for HEP/Nuclear PhysicistsItalian National School for HEP/Nuclear Physicists MC2000MC2000 MCNEG workshopMCNEG workshop KEK, SLAC, DESY, FNAL, INFN, Frascati, Karolinska, GranSasso, KEK, SLAC, DESY, FNAL, INFN, Frascati, Karolinska, GranSasso,

etc.etc. ATLAS, CMS, LHCbATLAS, CMS, LHCb Tutorials/lectures at universitiesTutorials/lectures at universities

U.K. - ImperialU.K. - Imperial Italy - Genoa, Bologna, Udine, Roma, TriesteItaly - Genoa, Bologna, Udine, Roma, Trieste

Near future tutorial coursesNear future tutorial courses DESY (Sept.30 - Oct.02, 2003)DESY (Sept.30 - Oct.02, 2003) IEEE NSS/MIC @ Portland, Oregon (Oct.19, 2003)IEEE NSS/MIC @ Portland, Oregon (Oct.19, 2003) FNAL (Oct.27 - Oct.29, 2003)FNAL (Oct.27 - Oct.29, 2003)


HyperNewsHyperNews HyperNews system was set up in April 2001 HyperNews system was set up in April 2001


HyperNewsHyperNews 19 categories 19 categories Not only “user-Not only “user-

developer”, but also developer”, but also

“user-user” “user-user”

information exchanges information exchanges

are quite intensive.are quite intensive.


HyperNews is quite activeHyperNews is quite active


Some postings are novice…Some postings are novice…


Some are excellent users Some are excellent users contributioncontribution


Technical ForumTechnical Forum In the Technical Forum, the Geant4 Collaboration, its user In the Technical Forum, the Geant4 Collaboration, its user

community and resource providers discuss:community and resource providers discuss: major user and developer requirements, user and developer major user and developer requirements, user and developer

priorities, software implementation issues, prioritized plans, priorities, software implementation issues, prioritized plans, physics validation issues, user support issuesphysics validation issues, user support issues

The Technical Forum is open to all interested parties The Technical Forum is open to all interested parties To be held at least 4 times per year (in at least two locales)To be held at least 4 times per year (in at least two locales)

The purpose of the forum is to:The purpose of the forum is to: Achieve, as much as possible, a mutual understanding of the Achieve, as much as possible, a mutual understanding of the

needs and plans of users and developers. needs and plans of users and developers. Provide the Geant4 Collaboration with the clearest possible Provide the Geant4 Collaboration with the clearest possible

understanding of the needs of its users.understanding of the needs of its users. Promote the exchange of information about physics validation Promote the exchange of information about physics validation

performed by Geant4 Collaborators and Geant4 users.performed by Geant4 Collaborators and Geant4 users. Promote the exchange of information about user support Promote the exchange of information about user support

provided by Geant4 Collaborators and Geant4 user provided by Geant4 Collaborators and Geant4 user communities.communities.

First Technical Forum meeting at TRIUMF during this collaboration First Technical Forum meeting at TRIUMF during this collaboration meeting, followed by one at CERN in October.meeting, followed by one at CERN in October.

Highlights ofHighlights ofnew developmentsnew developments


Event biasing in Geant4Event biasing in Geant4 Event biasing (variance reduction) technique is one of the most Event biasing (variance reduction) technique is one of the most

important requirements, which Geant4 collaboration is aware important requirements, which Geant4 collaboration is aware

of.of. This feature could be utilized by many application fields such as This feature could be utilized by many application fields such as

Radiation shieldingRadiation shielding DosimetryDosimetry

Since Geant4 is a toolkit and also all source code is open, the Since Geant4 is a toolkit and also all source code is open, the

user can do whatever he/she wants.user can do whatever he/she wants. CMS, ESA, Alice, and some other experiments have already CMS, ESA, Alice, and some other experiments have already

had their own implementations of event biasing options.had their own implementations of event biasing options. It’s much better and convenient for the user if Geant4 itself It’s much better and convenient for the user if Geant4 itself

provides most commonly used event biasing techniques.provides most commonly used event biasing techniques.


Biasing currently in Geant4Biasing currently in Geant4 Partial MARS migration Partial MARS migration

n, p, pi, K (< 5 GeV)n, p, pi, K (< 5 GeV) Since Geant4 0.0Since Geant4 0.0

General particle source moduleGeneral particle source module Primary particle biasingPrimary particle biasing Since Geant4 3.0Since Geant4 3.0

Radioactive decay moduleRadioactive decay module Physics process biasing in terms of decay products and Physics process biasing in terms of decay products and

momentum distributionmomentum distribution Since Geant4 3.0Since Geant4 3.0

Cross-section biasing (partial) for hadronic physics Cross-section biasing (partial) for hadronic physics Since Geant4 3.0Since Geant4 3.0

Leading particle biasingLeading particle biasing Since Geant4 4.0Since Geant4 4.0

Geometry based biasingGeometry based biasing Weight associating with real volume or artificial volumeWeight associating with real volume or artificial volume Since Geant4 5.0Since Geant4 5.0


RegionRegion Introducing the concept of Introducing the concept of

region.region. Set of geometry volumes, Set of geometry volumes,

typically of a sub-system;typically of a sub-system; Or any group of volumes;Or any group of volumes;

A cut in range is associated to a A cut in range is associated to a

region;region; a different range cut for each a different range cut for each

particle is allowed in a region.particle is allowed in a region. Typical UsesTypical Uses

barrel + end-caps of the barrel + end-caps of the

calorimeter can be a region;calorimeter can be a region; ““Deep” areas of support Deep” areas of support

structures can be a region.structures can be a region.

Region B

RegionB

DefaultRegion Region B

Region B

Region A

CC


Cuts per RegionCuts per Region Geant4 has had a unique and uniform production threshold (‘cut’) Geant4 has had a unique and uniform production threshold (‘cut’)

expressed in length (range of secondary).expressed in length (range of secondary). For all volumesFor all volumes One cut in range for each particleOne cut in range for each particle

By default is the same cut for all particlesBy default is the same cut for all particles.. Consistency of the physics simulatedConsistency of the physics simulated

A volume with dense material will not dominate the A volume with dense material will not dominate the simulation time at the expense of sensitive volumes with simulation time at the expense of sensitive volumes with light material.light material.

Appropriate length scales can vary greatly between different areas Appropriate length scales can vary greatly between different areas of a large detectorof a large detector E.g. a vertex detector (5 E.g. a vertex detector (5 m) and a muon detector (2.5 cm).m) and a muon detector (2.5 cm). Having a unique (low) cut can create a performance penalty.Having a unique (low) cut can create a performance penalty.

Requests from ATLAS, BABAR, CMS, LHCb, …, to allow several cutsRequests from ATLAS, BABAR, CMS, LHCb, …, to allow several cuts Enabling the tuning of production thresholds at the level of a Enabling the tuning of production thresholds at the level of a

sub-detector, i.e. sub-detector, i.e. regionregion.. Cuts are applied only for gamma, electron and positron.Cuts are applied only for gamma, electron and positron.

Full support since Geant4 5.1 (end April, 2003)Full support since Geant4 5.1 (end April, 2003) Comparable run-time performance compared to global cuts.Comparable run-time performance compared to global cuts.

Highlights ofHighlights ofUsers ApplicationsUsers Applications


Geant4 in HEPGeant4 in HEP

ATLAS (CERN-LHC)ATLAS (CERN-LHC)

22 x 22 x 44 m22 x 22 x 44 m33

15,000 ton15,000 ton 　　　　　　　　

4 million channels4 million channels

40 MHz readout40 MHz readout


ATLAS HEC G4 5.0 (true geometry, my toy ATLAS HEC G4 5.0 (true geometry, my toy analysis)analysis)

Ratio of observed energy for electron/pion beam


View of CMS muon system

Sliced view of CMS barrel detectors

View of 180 Higgs event simulated in CMS Tracker detector

CMS


ECAL + HCAL testbeamECAL + HCAL testbeam GEANT3 - GEANT4 comparisonGEANT3 - GEANT4 comparison

100 GeV pi+ ECAL+HCAL

CMS


A Typical event in the Testbeam

Red lines: Charged particleGreen lines : Optical Photons.

LHCb


Geant4 for beam Geant4 for beam transportationtransportation


X-Ray Surveys of X-Ray Surveys of Asteroids and MoonsAsteroids and Moons

Induced X-ray line emission:indicator of target composition(~100 m surface layer)

Cosmic rays,jovian electrons

Geant3.21Geant3.21

G4 “standard”G4 “standard”

Geant4 low-EGeant4 low-E

Solar X-rays, e, p

Courtesy SOHO EIT

C, N, O line emissions includedC, N, O line emissions included

ESA Space Environment & Effects Analysis SectionGeant4 in space Geant4 in space

sciencescience


ESA Space Environment & Effects Analysis Section

DESIREDESIRE (Dose Estimation by Simulation of the (Dose Estimation by Simulation of the ISS Radiation Environment)ISS Radiation Environment)

KTH Stockholm, ESTEC, EAC, NASA JohnsonKTH Stockholm, ESTEC, EAC, NASA Johnson Prediction of the ambient energetic particle Prediction of the ambient energetic particle

environment (environment (SPENVISSPENVIS & additional models) & additional models) Construction of COLUMBUS geometry in Construction of COLUMBUS geometry in

Geant4Geant4 Radiation transport, including secondary Radiation transport, including secondary

particle production, through the geometryparticle production, through the geometry Calculation of astronaut radiation dosesCalculation of astronaut radiation doses


WaterWater--styrophoamstyrophoam//bonebone--waterwater Stringest test on dose calculation algorithms Stringest test on dose calculation algorithms Accuracy of results are highly dependent on electron transport schemes Accuracy of results are highly dependent on electron transport schemes

(for Monte Carlo) and approximations (for TPS)(for Monte Carlo) and approximations (for TPS) GEANT4/GEANT4/GEANT3GEANT3 comparison with HELAX-TMS and PLATO comparison with HELAX-TMS and PLATO

Water Styrophoam0.0275 gcm-3

Heterogeneous PhantomHeterogeneous PhantomHeterogeneous PhantomHeterogeneous Phantom

10x10 cm2 Field5x5 cm2 Field


SummarySummary Geant4 is a worldwide collaboration providing a tool for Geant4 is a worldwide collaboration providing a tool for

simulation of particles interacting with matter.simulation of particles interacting with matter. Geant4’s object-oriented modular structure allows a large Geant4’s object-oriented modular structure allows a large

degree of functionality and flexibility.degree of functionality and flexibility. Geant4 can handle complicated and realistic geometries.Geant4 can handle complicated and realistic geometries. Geant4 provides sets of alternative physics models so that Geant4 provides sets of alternative physics models so that

users can choose appropriate models.users can choose appropriate models. Geant4 is being used not only in high energy and nuclear Geant4 is being used not only in high energy and nuclear

physics but also in accelerator physics, astrophysics, space physics but also in accelerator physics, astrophysics, space science and medical and other applications.science and medical and other applications.

Geant4 Collaboration try to offer extensive user support.Geant4 Collaboration try to offer extensive user support.

http://cern.ch/geant4/http://cern.ch/geant4/

introduction to geant4 gunter folger, cern ep/sft michel maire, lapp/annecy on behalf of the geant4...

Documents

geant4 g

geant4 collaboration30

high energy physics

wellisch introduction

gridka karlsruhephysics

gridka karlsruhewhat

space physics studies

cosmic ray physics