Логашенко И.Б. Современные методы обработки...

Логашенко И.Б.Современные методы обработки экспериментальных данных

GEANT4 – программный пакет для моделирования взаимодействия элементарных частиц с веществом

Логашенко И.Б. Современные методы обработки экспериментальных данных

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Документация

• Веб-страницаhttp://geant4.cern.ch

• Руководство пользователяhttp://geant4.web.cern.ch/geant4/UserDocumentation/UsersGuides/ForApplicationDeveloper/html/index.html

• Подробное описание классовhttp://geant4.cern.ch/bin/SRM/G4GenDoc.csh?flag=1http://www-geant4.kek.jp/lxr/source/

Логашенко И.Б. Современные методы обработки экспериментальных данных

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Запуск примера1. Зайдите на class-lin

2. Скопируйте директориюmkdir geant4cd geant4cp /home/Logashenko/geant4/setenv.sh .cp –r /home/Logashenko/geant4/simple .

3. Отредактируйте setenv.sh

4. Откомпилируйте примерsource setenv.shcd simplegmake

5. Запустите пример../bin/Linux-g++/exampleN03 run1.mac

Maria Grazia Pia, INFN Genova

http://cern.ch/geant4/geant4http://www.ge.infn.it/geant4

Overview of applicationsOverview of applications

Maria Grazia Pia, INFN Genova

ATLAS

Courtesy of ATLAS Collaboration

-100 1000 200 300 400 5000

600

100

200

300

400

500

700

800

Calorimeter Signal [nA]

Events

/10 n

A

180 GeV μ

HEC Testbeam: Muon Response Comparisons

Extensive comparisons with test beam data(activity in progress)

Maria Grazia Pia, INFN Genova

Maria Grazia Pia, INFN Genova

astrophysics--ray burstsray bursts

AGILE GLAST

Typical telescope: Tracker Calorimeter Anticoincidence

conversion electron interactions multiple scattering-ray production charged particle tracking

GLAST

GLAST

Maria Grazia Pia, INFN Genova

CT-simulation with a Rando phantomExperimental data with TLD LiF dosimeter

CT images used to define the geometry:

a thorax slice from a Rando

anthropomorphic phantom

Comparison with commercial treatment planning systems

M. C. LopesIPOFG-CROC Coimbra Oncological Regional Center

L. Peralta, P. Rodrigues, A. TrindadeLIP - Lisbon

Central-Axis depth dose

Profile curves at 9.8 cm depth

PLATO overestimates the dose at ~ 5% level

Maria Grazia Pia, INFN Genova

Dosimetry in interplanetary missions

Aurora Programme

Dose in astronaut resulting from Galactic Cosmic Rays

vehicle concept

Maria Grazia Pia, INFN Genova

GATEa Geant4 based simulation

platform, designed for PET and

SPECT

GATEa Geant4 based simulation

platform, designed for PET and

SPECT

Recently released as an open source software system

under GPL

>400 registered users worldwide

GATE Collaboration

Maria Grazia Pia, INFN Genova

Current implementation

ORNL and MIRD5 phantomsMale and Female

Geant4 analytical phantomORNL model, female

1 skull2 thyroid3 spine4 lungs5 breast6 heart7 liver8 stomach9 spleen10 kidneys11 pancreas12 intestine13 uterus and ovaries14 bladder15 womb16 leg bones17 arm bones

Geant4 analytical phantoms

Maria Grazia Pia, INFN Genova

Heavy ion beams

Geant4 simulation

Beam Track Reconstruction135 MeV/u 12C beam

NIRS N. Kanematsu, M. Komori - Nagoya K. Niwa, T.Toshito, T.Nakamura, T.Ban, N.Naganawa, S.Takahashi - Uchu-ken

M.Ozaki - Kobe S. Aoki - Aichi Y.Kodama - Naruto H.Yoshida - Ritsumei S.Tanaka - SLAC M. Asai, T. Koi - Tokyo N.Kokubu -

Gunma K. Yusa - Toho H.Shibuya, R.Ogawa, A. Shibazaki, T.Fukushima - KEK K. Amako,

K.Murakami, T. Sasaki

high spatial resolution emulsion chamber

Medical ion

beam

Events with > 50000

particles/event in detector

acceptance

CMS

~ 180 minutes to simulate 1 event with 55K generator tracks

Maria Grazia Pia, INFN Genova

- DNA

Relevance for space: astronaut and airline pilot radiation hazards, biological experiments

Applications in radiotherapy, radiobiology…

http://www.ge.infn.it/geant4/dna/

Prototyping

Multi-disciplinary Collaboration of

astrophysicists/space scientists

particle physicists medical physicists computer scientists biologists physicians

5.3 MeV particle in a cylindrical volume. The inner cylinder has a radius of 50 nm.

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 (and other applications, not only in the space domain)

User Application

http://cern.ch/geant4

EGS4, EGS5, EGSnrcGeant3, Geant4 MARSMCNP, MCNPX, A3MCNP, MCNP-DSP, MCNP4BMVP, MVP-BURNPenelopePeregrineTripoli-3, Tripoli-3 A, Tripoli-4

DPMEA-MCFLUKA GEMHERMESLAHETMCBEND MCU MF3DNMTCMONK MORSERTS&T-2000 SCALETRAXVMC++

...and I probably forgot some moreMany codes not publicly distributed

A lot of business around MC

The zoo

Monte Carlo codes presented at the MC200 Conference, Lisbon, October 2000Monte Carlo codes presented at the MC200 Conference, Lisbon, October 2000

Geant4 CollaborationGeant4 Collaboration

CERN, ESA, KEK, SLAC, TRIUMF, TJNL

INFN, IN2P3, PPARCBarcelona Univ., Budker Inst., Frankfurt Univ., Karolinska

Inst., Helsinki Univ., Lebedev Inst., LIP, Northeastern Univ. etc.

MoU basedDistribution, Development and User Support of Geant4

Toolkit + User application

Geant4 is a toolkittoolkit– i.e. you cannot “run” it out of the box

– You must write an application, which uses Geant4 tools

Consequences– There are no such concepts as “Geant4 defaults”

– You must provide the necessary information to configure your simulation

– You must deliberately choose which Geant4 tools to use

Guidance: we provide many examplesexamples– Novice ExamplesNovice Examples: overview of Geant4 tools

– Advanced ExamplesAdvanced Examples: Geant4 tools

Basic concepts

What you MUSTMUST do:– Describe your experimental set-upexperimental set-up

– Provide the primary particlesprimary particles input to your simulation– Decide which particlesparticles and physics modelsphysics models you want to

use out of those available in Geant4 and the precision of your simulation (cuts to produce and track secondary particles)

You may also want – To interact with Geant4 kernel to control control your simulation

– To visualise visualise your simulation configuration or results

– To produce histograms, tupleshistograms, tuples etc. to be further analysed

Geant4 Kernel

Provides central functionality of the toolkit

– handles runs, events, tracks, steps, hits, trajectories

– implements Geant4 as a state machine

– provides a framework for:

physics processes

visualization drivers

GUIs

persistency

histogramming/analysis

user code

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RunA run is a collection of events which are produced under identical conditions

Within a run, a user cannot change:– Detector or apparatus geometry – Physics process settings

By analogy to high energy physics a Geant4 run begins with the command “BeamOn”

– Detector is inaccessible once beam is on

At beginning of run:– Geometry is optimized for navigation

– Cross sections are calculated according to materials in the setup

– Low-energy cutoff values are defined

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EventAt beginning of processing, an event contains primary particles (from generator, particle gun, ...), which are pushed into a stack

During processing, each particle is popped from the stack and tracked

When the stack is empty, processing of the event is over

The class G4Event represents an event

At the end of processing it has the following objects:

– List of primary vertices and particles (the input)

– Hits collections

– Trajectory collections (optional)

– Digitizations collections (optional)

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TrackA track is a snapshot of a particle within its environment

– as the particle moves, the quantities in the snapshot change– at any particular instance, a track has position, physical quantities – it is not a collection of steps

Track object lifetime– created by a generator or physics process (e.g. decay)– deleted when it:

leaves world volume disappears (particle decays or is absorbed) goes to zero energy and no “at rest” process is defined user kills it

No track object survives the end of an event (not persistent)– User must take action to store track record in trajectory

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StepThe step is the basic unit of simulation– Has two points (pre-step, post-step)

– Contains the incremental particle information (energy loss, elapsed time, etc.)

– Each point contains volume and material information

– If step is limited by a boundary, the end point stands exactly on the boundary, but is logically part of next volume

– Hence boundary processes such as refraction and transition radiation can be simulated

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Interaction with Geant4 kernel

Geant4 design provides toolstools for a user application– To tell the kernel about your simulation configuration – To interact with Geant4 kernel itself

Geant4 tools for user interaction are base classesbase classes– You create your own concrete classyour own concrete class derived from the base classes– Geant4 kernel handles your own derived classes transparently through

their base class interface (polymorphism)(polymorphism)

Abstract base classesAbstract base classes for user interaction– User derived concrete classes are mandatory

Concrete base classesConcrete base classes (with virtual dummy methods) for user interaction– User derived classes are optionaloptional

Initialisation classesInitialisation classesInvoked at the initialization

G4VUserDetectorConstruction

G4VUserPhysicsList

Action classesAction classesInvoked during the execution loop

G4VUserPrimaryGeneratorAction

G4UserRunAction

G4UserEventAction

G4UserTrackingAction

G4UserStackingAction

G4UserSteppingAction

Mandatory classes:

G4VUserDetectorConstruction describe the experimental set-up

G4VUserPhysicsList select the physics you want to activate

G4VUserPrimaryGeneratorAction generate primary events

User classes

The main programGeant4 does not provide the main()main()– Geant4 is a toolkit!– The main() is part of the user application

In his/her main(), the user mustmust– construct G4RunManager G4RunManager (or his/her own derived class)– notify the G4RunManager mandatory user classes derived from

G4VUserDetectorConstruction G4VUserPhysicsList G4VUserPrimaryGeneratorAction

The user may define in his/her main()– optional user action classes– VisManager, (G)UI session

{ … // Construct the default run manager G4RunManager* runManager = new G4RunManagerG4RunManager;;

// Set mandatory user initialization classes MyDetectorConstruction* detector = new MyDetectorConstructionMyDetectorConstruction;; runManager->SetUserInitialization(detector); runManager->SetUserInitialization(new MyPhysicsListMyPhysicsList);

// Set mandatory user action classes runManager->SetUserAction(new MyPrimaryGeneratorActionMyPrimaryGeneratorAction);

// Set optional user action classes MyEventAction* eventAction = new MyEventAction()MyEventAction();; runManager->SetUserAction(eventAction); MyRunAction* runAction = new MyRunAction()MyRunAction();; runManager->SetUserAction(runAction); …}

main()

Describe the experimental set-up

Derive your own concrete class from the G4VUserDetectorConstructionG4VUserDetectorConstruction abstract base class

Implement the Construct()Construct() method – construct all necessary materials

– define shapes/solids required to describe the geometry

– construct and place volumes of your detector geometry

– define sensitive detectors and identify detector volumes to associate them to

– associate magnetic field to detector regions

– define visualisation attributes for the detector elements

How to define materials

PVPhysicalVolume* MyDetectorConstruction::Construct() {

… a = 207.19*g/mole; density = 11.35*g/cm3; G4Material* lead = new new G4MaterialG4Material(name="Pb", z=82., a, density);

density = 5.458*mg/cm3; pressure = 1*atmosphere; temperature = 293.15*kelvin; G4Material* xenon = new new G4MaterialG4Material(name="XenonGas", z=54.,

a=131.29*g/mole, density,

kStateGas, temperature, pressure); ... }

Different kinds of materials can be defined

IsotopesElementsMoleculesCompounds and mixtures

Lead

Xenongas

For example, a scintillator consisting of Hydrogen and Carbon:

G4double a = 1.01*g/mole; G4Element* H = new G4ElementG4Element(name="Hydrogen", symbol="H", z=1., a); a = 12.01*g/mole; G4Element* C = new G4ElementG4Element(name="Carbon", symbol="C", z=6., a);

G4double density = 1.032*g/cm3; G4Material* scintillatorG4Material* scintillator = new G4MaterialG4Material(name = "Scintillator", density, numberOfComponents = 2);

scintillator -> AddElement(C, numberOfAtoms = 9); scintillator -> AddElement(H, numberOfAtoms = 10);

How to define a compound material

Define detector geometryThree conceptual layers– G4VSolid shape, size

– G4LogicalVolume material, sensitivity, magnetic field, etc.

– G4VPhysicalVolume position, rotation

A unique physical volume (the world volume), which represents the experimental area, must exist and fully contain all other components

World

Volume B (daughter)

Volume A (mother)

e.g.: Volume A is mother of Volume B

The mother must contain the daughter volume entirely

solidWorld = new G4Box(“World", halfWorldLength, halfWorldLength, halfWorldLength); logicWorld = new G4LogicalVolume(solidWorld, air, "World", 0, 0, 0); physicalWorld = new G4PVPlacement(0, //no rotation G4ThreeVector(), // at (0,0,0) logicWorld, // its logical volume "World", // its name 0, // its mother volume false, // no boolean operations 0); // no magnetic field

solidTarget = new G4Box(“Target", targetSize, targetSize, targetSize);logicTarget = new G4LogicalVolume(solidTarget, targetMaterial, "Target",0,0,0);physicalTarget = new G4PVPlacement(0, // no rotation positionTarget, // at (x,y,z) logicTarget, // its logical volume "Target", // its name logicWorld, // its mother volume false, // no boolean operations 0); // no particular field

How to build the World

How to build a volume inside the World

Select physics processesGeant4 does not have any default particles or processes

Derive your own concrete class from the G4VUserPhysicsList abstract base class– define all necessary particles

– define all necessary processes and assign them to proper particles

– define production thresholds (in terms of range)

Pure virtual methods of G4VUserPhysicsList

to be implemented by the user in his/her concrete derived class

ConstructParticles()ConstructProcesses()SetCuts()

PhysicsList: particles and cuts

void MyPhysicsList :: ConstructParticles(){ G4Electron::ElectronDefinition(); G4Positron::PositronDefinition(); G4Gamma::GammaDefinition();}

Define the the particlesparticles involved in the simulation

void MyPhysicsList :: SetCuts(){ SetCutsWithDefault(); }

Set the production threshold

MyPhysicsList :: MyPhysicsList(): G4VUserPhysicsList(){ defaultCutValue = 1.0*cm;}

Define production thresholdsproduction thresholds (the same for all particles)

PhysicsList: more about cutsMyPhysicsList :: MyPhysicsList(): G4VUserPhysicsList(){ // Define production thresholds cutForGamma = 1.0*cm; cutForElectron = 1.*mm; cutForPositron = 0.1*mm; } ;

void MyPhysicsList :: SetCuts(){ // Assign production thresholds

SetCutValue(cutForGamma, "gamma"); SetCutValue(cutForElectron, "e-"); SetCutValue(cutForPositron, "e+");}

The user can define different cuts for different particles ordifferent regions

void MyPhysicsList :: ConstructParticles() { if (particleName == "gamma") { pManager->AddDiscreteProcess(new G4PhotoElectricEffect()); pManager->AddDiscreteProcess(new G4ComptonScattering()); pManager->AddDiscreteProcess(new G4GammaConversion()); } else if (particleName == "e-") { pManager->AddProcess(new G4MultipleScattering(), -1, 1,1); pManager->AddProcess(new G4eIonisation(), -1, 2,2); pManager->AddProcess(new G4eBremsstrahlung(), -1,-1,3); } else if (particleName == "e+") { pManager->AddProcess(new G4MultipleScattering(), -1, 1,1); pManager->AddProcess(new G4eIonisation(), -1, 2,2); pManager->AddProcess(new G4eBremsstrahlung(), -1,-1,3); pManager->AddProcess(new G4eplusAnnihilation(), 0,-1,4); } }

Select physics processes to be activated for each particle type

Physics List: processes

The Geant4 Standard electromagnetic processes are selected in this example

Primary events

Derive your own concrete class from the G4VUserPrimaryGeneratorAction abstract base class

Implement the virtual member function GeneratePrimaries()

Define primary particles providing:

Particle typeInitial positionInitial directionInitial energy

MyPrimaryGeneratorAction:: My PrimaryGeneratorAction(){

G4int numberOfParticles = 1; particleGun = new G4ParticleGunG4ParticleGun (numberOfParticles); G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable(); G4ParticleDefinition* particle = particleTable->FindParticle(“e-“); particleGun->SetParticleDefinition(particle); particleGun->SetParticlePosition(G4ThreeVector(x,y,z)); particleGun->SetParticleMomentumDirection(G4ThreeVector(x,y,z)); particleGun->SetParticleEnergy(energy);}}

void MyPrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent){ particleGun->GeneratePrimaryVertex(anEvent); }

Generate primary particles

Optional User Action classes

Five concrete base classes whose virtual member functionsvirtual member functions the user may override to gain control of the simulation at various stages– G4UserRunAction

– G4UserEventAction

– G4UserTrackingAction

– G4UserStackingAction

– G4UserSteppingAction

Each member function of the base classes has a dummy implementation– Empty implementation: does nothing

The user may implement the member functions he desires in his/her derived classes

Objects of user action classes must be registered with G4RunManager

Optional User Action classes

G4UserRunActionG4UserRunActionBeginOfRunAction(const G4Run*)– For example: book histograms

EndOfRunAction(const G4Run*)– For example: store histograms

G4UserEventActionG4UserEventActionBeginOfEventAction(const G4Event*)– For example: perform and event selection

EndOfEventAction(const G4Event*)– For example: analyse the event

G4UserTrackingActionG4UserTrackingActionPreUserTrackingAction(const G4Track*)– For example: decide whether a trajectory should be stored or not

PostUserTrackingAction(const G4Track*)

Optional User Action classesG4UserSteppingActionG4UserSteppingAction

UserSteppingAction(const G4Step*)– For example: kill, suspend, postpone the track– For example: draw the step

G4UserStackingActionG4UserStackingActionPrepareNewEvent()– For example: reset priority control

ClassifyNewTrack(const G4Track*)– Invoked every time a new track is pushed – For example: classify a new track (priority control)

Urgent, Waiting, PostponeToNextEvent, Kill

NewStage()– Invoked when the Urgent stack becomes empty– For example: change the classification criteria – For example: event filtering (event abortion)

Initialisationmain Run manager user detector

const ructionuser physics

list

1: initialize2 : const ruct

3: material const ruct ion

4: geometry construct ion5: world volume

6 : const ruct

7 : physics process const ruction

8: set cuts

Describe your experimental set-up

Activate physics processes appropriate to your experiment

Beam Onmain Run Manager Geometry

managerEvent

generatorEvent

Manager

1: Beam On2: close

3: generate one event

4: process one event

5: open

Generate primary events according to distributions relevant to your experiment

Event processingEvent

managerStacking manager

Tracking manager

Stepping manager

User sensitive detector

1: pop

2: process one track3: Stepping

4: generate hits

5: secondaries

6: push

Record the physics quantities generated by the simulation, that are relevant to your experiment

Define three kinds of actions:

– AtRestAtRest actions: decay, annihilation …

– AlongStepAlongStep actions: continuous interactions occuring along the path, like ionisation

– PostStepPostStep actions: point-like interactions, like decay in flight, hard radiation…

A process can implement any combination of the three AtRest, AlongStep and PostStep actions: eg: decay = AtRest + PostStep

Each action defines two methods:

– GetPhysicalInteractionLength()GetPhysicalInteractionLength() used to limit the step size

either because the process triggers an interaction or a decayor in other cases, like fraction of energy loss, geometry boundary, user’s limit…

– DoIt()DoIt()• implements the actual action to be applied to the track• implements the related production of secondaries

G4VProcesG4VProcesss

AlongStep

PostStep

Abstract class defining the common interface of all processes in Geant4

Multiple scattering BremsstrahlungIonisationAnnihilationPhotoelectric effect Compton scattering Rayleigh effect conversione+e- pair productionSynchrotron radiationTransition radiationCherenkovRefractionReflectionAbsorptionScintillationFluorescenceAuger

Electromagnetic physics

High energy extensionsHigh energy extensions– needed for LHC experiments, cosmic ray

experiments…

Low energy extensionsLow energy extensions– fundamental for space and medical applications, dark

matter and 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 release (1997)

Further extensions (facilitated by the OO technology)

All obeying to the same abstract Process interface transparent to tracking

Detector Description

Alexander Howard, CERN

Acknowledgements: Slides produced by J.Apostolakis, G.Cosmo, M. Asai

http://cern.ch/geant4

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Unit systemUnit system Geant4 has no default unit. To give a number,

unit must be “multiplied” to the number. for example : G4double width = 12.5*m; G4double density = 2.7*g/cm3; If no unit is specified, the internal G4 unit will be used,

but this is discouraged ! Almost all commonly used units are available. The user can define new units. Refer to CLHEP: SystemOfUnits.h

Divide a variable by a unit you want to get. G4cout << dE / MeV << “ (MeV)” << G4endl;

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System of UnitsSystem of Units System of units are defined in CLHEP, based on:

millimetre (mm), nanosecond (ns), Mega eV (MeV), positron charge (eplus) degree Kelvin (kelvin), the amount of substance (mole), luminous intensity (candela), radian (radian), steradian (steradian)

All other units are computed from the basic ones. In output, Geant4 can choose the most appropriate unit to

use. Just specify the category for the data (Length, Time, Energy, etc…):

G4cout << G4BestUnit(StepSize, “Length”);

StepSize will be printed in km, m, mm or … fermi, depending on its value

50

Isotopes, Elements and MaterialsIsotopes, Elements and Materials

G4Isotope and G4Element describe the properties of the atoms: Atomic number, number of nucleons, mass of

a mole, shell energies Cross-sections per atoms, etc…

G4Material describes the macroscopic properties of the matter: temperature, pressure, state, density Radiation length, absorption length, etc…

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Material: moleculeMaterial: molecule A Molecule is made of several elements

(composition by number of atoms):

a = 1.01*g/mole;G4Element* elH = new G4Element("Hydrogen",symbol="H",z=1.,a);a = 16.00*g/mole;G4Element* elO = new G4Element("Oxygen",symbol="O",z=8.,a);density = 1.000*g/cm3;G4Material* H2O = new G4Material("Water",density,ncomp=2);H2O->AddElement(elH, natoms=2);H2O->AddElement(elO, natoms=1);

52

Material: compound Material: compound Compound: composition by fraction of mass

a = 14.01*g/mole;

G4Element* elN =

new G4Element(name="Nitrogen",symbol="N",z= 7.,a);

a = 16.00*g/mole;

G4Element* elO =

new G4Element(name="Oxygen",symbol="O",z= 8.,a);

density = 1.290*mg/cm3;

G4Material* Air =

new G4Material(name="Air",density,ncomponents=2);

Air->AddElement(elN, 70.0*perCent);

Air->AddElement(elO, 30.0*perCent);

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Material: mixtureMaterial: mixture Composition of compound materials

G4Element* elC = …; // define “carbon” element

G4Material* SiO2 = …; // define “quartz” material

G4Material* H2O = …; // define “water” material

density = 0.200*g/cm3;

G4Material* Aerog =

new G4Material("Aerogel",density,ncomponents=3);

Aerog->AddMaterial(SiO2,fractionmass=62.5*perCent);

Aerog->AddMaterial(H2O ,fractionmass=37.4*perCent);

Aerog->AddElement (elC ,fractionmass= 0.1*perCent);

54

Example: gasExample: gas It may be necessary to specify

temperature and pressure (dE/dx computation affected)

G4double density = 27.*mg/cm3; G4double temperature = 325.*kelvin; G4double pressure = 50.*atmosphere;

G4Material* CO2 = new G4Material(“CarbonicGas", density, ncomponents=2 kStateGas, temperature, pressure); CO2->AddElement(C,natoms = 1); CO2->AddElement(O,natoms = 2);

55

Define detector geometryDefine detector geometry

G4Box

G4Tubs

G4VSolid G4VPhysicalVolume

G4Material

G4VSensitiveDetector

G4PVPlacement

G4PVParameterised

G4VisAttributes

G4LogicalVolume

Three conceptual layers G4VSolid -- shape, size G4LogicalVolume -- daughter physical volumes, material, sensitivity, user limits, etc. G4VPhysicalVolume -- position, rotation

56

Define detector geometry Basic strategy

G4VSolid* pBoxSolid =

new G4Box(“aBoxSolid”,

1.*m, 2.*m, 3.*m);

G4LogicalVolume* pBoxLog =

new G4LogicalVolume( pBoxSolid,

pBoxMaterial, “aBoxLog”, 0, 0, 0);

G4VPhysicalVolume* aBoxPhys =

new G4PVPlacement( pRotation,

G4ThreeVector(posX, posY, posZ),

pBoxLog, “aBoxPhys”, pMotherLog,

0, copyNo);

A volume is placed in its mother volume. Position and rotation of the daughter

volume is described with respect to the local coordinate system of the mother

volume. The origin of mother volume’s local coordinate system is at the center

of the mother volume.

Daughter volume cannot protrude from mother volume.

Solid : shape and sizeLogical volume : + material, sensitivity, etc.

Physical volume : + rotation and position

57

G4LogicalVolumeG4LogicalVolumeG4LogicalVolume(G4VSolid* pSolid, G4Material* pMaterial, const G4String& name, G4FieldManager* pFieldMgr=0, G4VSensitiveDetector* pSDetector=0, G4UserLimits* pULimits=0, G4bool optimise=true);

Contains all information of volume except position:• Shape and dimension (G4VSolid)• Material, sensitivity, visualization attributes• Position of daughter volumes• Magnetic field, User limits• Shower parameterisation

Physical volumes of same type can share a logical volume. The pointers to solid and material must be NOT null Once created it is automatically entered in the LV store It is not meant to act as a base class

58

G4PVPlacementG4PVPlacementG4PVPlacement(G4RotationMatrix* pRot,

const G4ThreeVector& tlate, G4LogicalVolume* pCurrentLogical,

const G4String& pName, G4LogicalVolume* pMotherLogical, G4bool pMany, G4int pCopyNo);

Single volume positioned relatively to the mother volume In a frame rotated and translated relative to the coordinate

system of the mother volume Three additional constructors:

A simple variation: specifying the mother volume as a pointer to its physical volume instead of its logical volume.

Using G4Transform3D to represent the direct rotation and translation of the solid instead of the frame

The combination of the two variants above

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G4PVPlacementG4PVPlacement(G4RotationMatrix* pRot, // rotation of mother frame

const G4ThreeVector &tlate, // position in rotated frame

G4LogicalVolume *pDaughterLogical,

const G4String &pName,

G4LogicalVolume *pMotherLogical,

G4bool pMany, // ‘true’ is not supported yet…

G4int pCopyNo, // unique arbitrary integer

G4bool pSurfChk=false); // optional boundary check Single volume positioned relatively to the mother volume.

rotation

translation in

rotated frame

Mother volume

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Alternative G4PVPlacementG4PVPlacement(

G4Transform3D(G4RotationMatrix &pRot, // rotation of daughter frame

const G4ThreeVector &tlate), // position in mother frame

G4LogicalVolume *pDaughterLogical,

const G4String &pName,

G4LogicalVolume *pMotherLogical,

G4bool pMany, // ‘true’ is not supported yet…

G4int pCopyNo, // unique arbitrary integer

G4bool pSurfChk=false); // optional boundary check Single volume positioned relatively to the mother volume.

rotation

Mother volume

translation in

mother frame

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G4VSolidG4VSolid Abstract class. All solids in

Geant4 derive from it Defines but does not

implement all functions required to:

• compute distances to/from the shape

• check whether a point is inside the shape

• compute the extent of the shape

• compute the surface normal to the shape at a given point

Once constructed, each solid is automatically registered in a specific solid store

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CSG: G4Box, G4Tubs

G4Box(const G4String &pname, // name

G4double half_x, // X half size

G4double half_y, // Y half size

G4double half_z); // Z half size

G4Tubs(const G4String &pname, // name

G4double pRmin, // inner radius

G4double pRmax, // outer radius

G4double pDz, // Z half length

G4double pSphi, // starting Phi

G4double pDphi); // segment angle

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Other CSG solids

G4Cons

G4Para(parallelepipe

d)G4Trd

G4Trap

G4SphereG4Orb

(full solid sphere)

G4Torus

Consult to Consult to Section 4.1.2 of Section 4.1.2 of Geant4 Application Developers Geant4 Application Developers GuideGuide for all available shapes. for all available shapes.

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Other Specific CSG solids

G4Polyhedra

G4EllipticalTube

G4Ellipsoid

G4EllipticalCone

G4HypeG4Tet(tetrahedra)

G4TwistedBox G4TwistedTrdG4TwistedTrap

G4TwistedTubs

Consult to Consult to Section 4.1.2 of Geant4 Section 4.1.2 of Geant4 Application Developers GuideApplication Developers Guide for all for all available shapes.available shapes.

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Boolean Solids Solids can be combined using boolean operations:

G4UnionSolid, G4SubtractionSolid, G4IntersectionSolid Requires: 2 solids, 1 boolean operation, and an (optional)

transformation for the 2nd solid 2nd solid is positioned relative to the coordinate system of the 1st solid Result of boolean operation becomes a solid. Thus the third solid can

be combined to the resulting solid of first operation. Solids to be combined can be either CSG or other Boolean solids. Note: tracking cost for the navigation in a complex Boolean solid is

proportional to the number of constituent CSG solids

G4UnionSolid G4IntersectionSolidG4SubtractionSolid