Monte carlo and analysis tool
study
Shi-hong yao
motivation
Geant4
-- interest, because it’s seem to very
useful for many science domain.
-- to understand how to design a big program?
-- work need…if I need to add/change something.
ROOT, Mysql
-- for analysis, histogram, data store.
In your Main
Required
G4VUserDetectorConstruction
G4VUserPhysicsList
User must be implement
his own classes drivered
from the three abstract
classes respective and
register them to the
RunManager.
G4VUserPrimaryGeneratorAction
Optional
G4RunManager
G4UserRunAction
G4UserEventAction
G4RunManager is the only
manager class in Geant4 kernel.
SetUserInitialization(…)
SetUserAction(…)
Initialize();
beamOn(numberOfEvent);
G4UserStackingAction
G4UserTrackingAction
G4UserSteppingAction
You can collect data from these
classes or even change/interfere
the process in order to reach
some purpose.
In your Main
G4UIManager
G4UIterminal
In interactive mode,
It’s hard-coded batch mode,
G4UImanager* UI =G4UImanager::GetUIpointer();
UI->ApplyCommand(“/run/verbose 1");
UI->ApplyCommand(“/control/execute macrofile");
#macro file
#set verbose level
/run/verbose 2
#start run
/run/beamOn 100
G4UIsession* session = new G4UIterminal;
session->SessionStart();
// Work… work… work…your work…
delete session;
Idle> your command
Geant4 as a state machine
PreInit
Initialized
Idle
beamOn
GeomClose
exit
Quit
EventProc
Abort
Basic - Units
• Length(meter)
km, m, cm, mm, um, nm, fm …
• Surface(meter2)
km2, m2, cm2, mm2, barn,
mbarn, …
• Angle(radian)
rad, mrad, sr, deg
…
…and a lot of extend unit…
• Energy(electron volt)
eV, keV, MeV, …, PeV J(joule)
• Mass(gram)
mg, g, kg
• Time(second)
s, ms, mus, ns, ps
The units in blue are defined by one.
global
•
•
When you read-in a value, it is recommend to set the units.
If the units are not specified, it implicitly use the internal units.
•
•
•
You can output your data with the units you wish.
By divide the unit.
You can get the list of units by static function
G4UnitDefinition::PrintUnitsTable() or UI command /units/list .
density = 12.0*g/cm3;
length = 1*cm;
G4cout << density/(g/cm3);
G4cout << length/cm;
Call from
G4RunManager
Construct Detector
G4VUserDetectorConstruction
Public
myDetectorConstruction
your own concrete class
Construct(); //pure virtual method which is invoked by
G4RunManager when it's Initialize() method is invoked. This
method must return the G4VPhysicalVolume pointer which
represents the world volume.
Material – molecule or mixture
It include:
Name,
atomic number Z,
number of nucleons N,
atomic mass A,
Or, Isotopes.
G4Element
H
x2
It include:
Name,
Density,
State,
Temperature,
Pressure,
Or Components
G4Material
H2O
G4Element
O
x1
G4Material
Other
…
G4Element* elH = new G4Element(name="Hydrogen", symbol="H" , z= 1., a = 1.01*g/mole);
G4Element* elO = new G4Element(name="Oxygen" ,symbol="O" , z= 8., a 16.00*g/mole);
G4Material* H2O = new G4Material(name="Water", density = 1.000*g/cm3, ncomponents=2);
H2O->AddElement (elH, natoms=2);
H2O->AddElement (elO, natoms=1);
Or get material from Geant4 database
G4NistManager* man = G4NistManager::Instance();
G4Material* H2O = man->FindOrBuildMaterial("G4_WATER");
See the list: Geant4 Material Database
Detector construct
Return to
G4RunManager
SD
World volume
G4LogicalVolume
LogiVolDaughter
G4Tube
G4PVPlacement
G4PVPlacement
PhysicsVolume
G4LogicalVolume
LogiVolMother
Air
G4PVPlacement
other
G4BOX
G4LogicalVolume
PhysicsWorld
LogiVolOther
…
SolidBox = new G4Box(name, xLangth, yLangth, zLangth);
LogiVolMother = new G4LogicalVolume( SolidBox, Air, name2);
LogiVolDaughter = new G4LogicalVolume( SolidTube, H2O, name3);
PhysicsVolume = new G4PVPlacement( Rot, trans, LogiVolDaughter , name?, LogiVolMother, 0, copyNo);
PhysicsWorld = new G4PVPlacement(0, G4ThreeVector(), LogicalVolume, “WORLD”, 0, false, 0);
Call from
G4RunManager
Physics list
G4VUserPhysicsList
Public
myPhysicsList
your own concrete class
Three pure virtual method must be implemented by the user.
ConstructParticle(); // construction of particles
ConstructProcess(); // construct processes and register them to particles
SetCuts(); // setting a range cut value for all particles
Other method for using:
AddTransportation(); //register the G4Transportation class which describes
the particle motion in space and time with all particles.
SetCutsWithDefault();//
G4Proton
G4Gamma
G4BosonConstructor
pure virtual method.
User must define "All PARTICLE
TYPES" include not only primary
particles, but also all secondaries.
G4LeptonConstructor
ConstructParticle()
G4MesonConstructor
G4Electron
G4MuonPlus
G4BarionConstructor
…
G4IonConstructor
More than 100 types of
particles are provided by
default.
G4ShortlivedConstructor.
Define particles one by one or use
this six utility classes, corresponding
to each of the particle categories.
In constructParticle(),
explicitly invoke static methods of all particle classes
G4Proton::ProtonDefinition();
G4Gamma::GammaDefinition();
G4MuonMinus::MuonMinusDefinition();
…
#include “G4LeptonConstructor.hh”
G4LeptonConstructor pConstructor;
pConstructor.ConstructParticle();
What is process
Physics processes describe how particles interact with materials.
G4VProcess
Abstract base class for all physics processes.
GPIL method:
PostStepGetPhysicalInteractionLength(…);
AlongStepGetPhysicalInteractionLength(…);
AtRestGetPhysicalInteractionLength(…);
DoIt method:
AlongStepDoIt(..);
PostStepDoIt(…);
AtRestDoIt(…);
G4Transportation
The GPIL method gives the step length from
the current space-time point to the next
space-time point. It does this by calculating
the probability of interaction based on the
process's cross section information.
The DoIt method implements the
details of the interaction, changing the
particle's energy, momentum, direction
and position, and producing secondary
tracks if required.
G4Cerenkov
G4ComptonScattering
G4eplusAnnihilation
…
seven major categories of processes,
electromagnetic, hadronic, transportation, decay, optical, photolepton_hadron, and parameterisation.
ConstructProcess
G4Gamma
G4ProcessManager
G4ComptonScattering
Register related physics
process to each particle
type. This maybe a big
project.
…
G4PhotoElectricEffect
AddTransportation();
particle = G4Gamma::GammaDefinition();
G4ProcessManager* pmanager = particle->GetProcessManager();
G4PhotoElectricEffect * thePhotoElectricEffect = new G4PhotoElectricEffect();
pmanager->AddDiscreteProcess(thePhotoElectricEffect);
pmanager->AddDiscreteProcess(theComptonEffect);
pmanager->AddDiscreteProcess(thePairProduction);
… a lot ...
Range Cut
SetCuts
pure virtual method.
A "unique cut value in range“ should be defined as a distance which is internally converted to an
energy for individual materials.
Geant4 recommend cut value is 1.0 mm.
SetCutsWithDefault(); or defaultCutValue = 1.0*mm;
//set cut value for different particle types.
SetCutValue(cutForGamma, "gamma");
SetCutValue(cutForElectron, "e-");
…
Call from
G4RunManager
Primary Generation
G4VUserPrimaryGeneratorAction
Public
myPrimaryGeneratorAction
your own concrete class
GeneratePrimaries(G4Event* anEvent );
Pure virtual method which is invoked at the
beginning of each event.
G4VPrimaryGenerator
This is an abstract base class of
all of primary generators.
GeneratePrimaryVertex() = 0;
Public
G4ParticleGun
G4GeneralParticleSource
This class generates primary
particle(s) with a given
momentum and position.
For spatial distributions
http://reat.space.qinetiq.com/gps/
G4HEPEvtInterface
G4int n_particle = 1;
particleGun = new G4ParticleGun(n_particle);
particleGun->SetParticleDefinition(G4Proton::ProtonDefinition());
particleGun->SetParticleEnergy(120.0*GeV);
particleGun->SetParticlePosition(G4ThreeVector(0.0*m, 0.0*m, -5.0*m));
particleGun->GeneratePrimaryVertex(anEvent);
PYTHIA8
PYTHIA is a program for the generation of high-energy physics events, i.e. for the description of
collisions at high energies between elementary particles such as e+, e-, p and pbar in various
combinations.
……Excerpt from PYTHIA’s site
Three step of PYTHIA
Only PYTHIA itself:
1. Initialization
2. Event loop
3. Finish, statistics
Pythia pythia;
pythia.readString(“ProcessGroup:ProcessName = ON|OFF”);
//List see appendix 1
pythia.readFile(FileName);
…
pythia.init(idA, idB, eA, eB);
//pythia.init(idA, idB, eCM);
//Currently the program only works with pp, pbar p, e+e- and
μ+μ- incoming beams.
while(!pythia.next());
//event record found in pythia.event
pythia.event.list();
//do something….
pythia.statistics();
PYTHIA play a generator role
myPrimaryGeneratorAction
PYTHIA
G4ParticleGun
Particle remnants sent to the particle gun.
while(!pythia.next());
for (int i = 1; i < pythia.event.size(); i++)
{
Pythia8::Particle par = pythia.event[i];
if (par.status() > 0)
{
ParticleGun -> SetParticlePosition(G4ThreeVector(par.xProd()*mm,par.yProd()*mm,par.zProd()*mm));
ParticleGun -> SetParticleDefinition(ParticleTable->FindParticle(par.id()));
ParticleGun -> SetParticleMomentumDirection(G4ThreeVector(par.px(),par.py(),par.pz())*GeV);
ParticleGun -> SetParticleEnergy(par.pAbs()*GeV);
ParticleGun -> GeneratePrimaryVertex(anEvent);
}
}
visualization
What you can visualize
-Detector components
-A hierarchical structure of physical volumes
-Particle trajectories and tracking steps
-Hits of particles in detector components.
HepRep/WIRED
OpenGL
DAWN
???
OpenGL
View directly from Geant4 when you are running, it
can zoom, rotate, translate, but poor for graphics.
Addition on follow two line before session start.
G4VisManager* visManager = new G4VisExecutive;
visManager->Initialize();
Then execute your program and stop at idle state.
#Create an empty scene ("world" is default):
/vis/scene/create
#Create a scene handler for a specific graphics system
/vis/open OGLIX
#/vis/open DAWNFILE
#/vis/open HepRepFile
# for drawing the tracks,hits
/vis/scene/add/trajectories
/vis/scene/add/hits
/tracking/storeTrajectory 1
#too many tracks may cause core dump
/vis/scene/endOfEventAction accumulate | refresh
/run/beamOn number
WIRED
Replace OGLIX by HepRepFile
beamOn and produce G4DataX.heprep by Geant4, X is the event number.
View in the WIRED Event Display, you need to install java runtime environment.
And download WIRED from here.
>java -jar HepRApp.jar -file G4DataX.heprep
It can zoom, rotate, translate,…
click to show attributes,
control visibility from hierarchical (tree) view of data
Export to many vector graphic formats (PostScript, PDF, etc.)
Data store -- Mysql
• Benefits
It is a well-designed database manager system.
It is convenient for query specify data with some condition.
Some calculate capability, average, maximum, minimum, and so on.
Run two or more program parallelize without worry about the file conflict.
• Short
You need one computer to do the server.
You can’t run simulation without the server.
Efficiency depend on the network.
You still need other analysis tool for complex calculate.
Using Mysql API
Get the data you want to store from Geant4 or PYTHIA.
According to the Mysql syntax, combine the data into string.
Through function mysql_query() or mysql_
#include “mysql.hh” if you can’t find this file, please contact your system manager….
MYSQL *conn = mysql_init(NULL);
mysql_real_connect(conn, host,user,pass,database, 0, NULL, 0)
mysql_query(conn, querystring);
//receive returned data…
result = mysql_store_result(conn);
for(num_rows=0;row = mysql_fetch_row(result);num_rows++){
eventlist[num_rows]=atoi(row[0]);
}
mysql_free_result(result);
mysql_close(conn);
Data store – ROOT
• Benefits
ROOT is a very efficient and complete frameworks for analysing large amounts
of data.
Root file can store many type of object include TTree.
Structure of TTree is similar to mysql but root provide many fancy function for
drawing histogram.
The data directly store at local disk – fast.
• Short
If data has some problem or error, it’s inconvenient to find out and correct.
User Action
G4UserRunAction
G4UserEventAction
//at the beginning of the BeamOn() method
virtual void BeginOfRunAction(
const G4Run* aRun);
//at the end of the BeamOn() method
virtual void EndOfRunAction(
const G4Run* aRun);
virtual void BeginOfEventAction(
virtual void EndOfEventAction(
const G4Event* anEvent);
const G4Event* anEvent);
G4UserStackingAction
void PrepareNewEvent ();
G4ClassificationOfNewTrack ClassifyNewTrack(const G4Track*)
void NewStage () NewStage
G4UserTrackingAction
void PreUserTrackingAction(
void PostUserTrackingAction(
G4UserSteppingAction
void UserSteppingAction(const G4Step*)
const G4Track*);
const G4Track*)
Feature work
• I have not yet understand all the detail/concept of Geant4.
• Try to understand the physics process.
Thanks for Listening.
Appendix 1
Currently implemented processes, complete with respect to groups, but with some individual processes missing for lack
of space (represented by “...”).
In the names, a “2” separates initial and final state, an “(s:X)”, “(t:X)” or “(l:X)” occasionally appends info on an s- or tchannel- or loop-exchanged particle X.
ProcessGroup
ProcessName
SoftQCD
minBias,elastic, singleDiffractive,
doubleDiffractive
HardQCD
gg2gg, gg2qqbar, qg2qg, qq2qq, qqbar2gg,
qqbar2qqbarNew, gg2ccbar, qqbar2ccbar,
gg2bbbar, qqbar2bbbar
PromptPhoton
qg2qgamma, qqbar2ggamma, gg2ggamma,
ffbar2gammagamma, gg2gammagamma
WeakBosonExchange
ff2ff(t:gmZ), ff2ff(t:W)
WeakSingleBoson
ffbar2gmZ, ffbar2W, ffbar2ffbar(s:gm)
WeakDoubleBoson
ffbar2gmZgmZ, ffbar2ZW, ffbar2WW
WeakBosonAndParton
WeakBosonAndParton qqbar2gmZg,
qg2gmZq, ffbar2gmZgm, fgm2gmZf
qqbar2Wg, qg2Wq, ffbar2Wgm, fgm2Wf
ProcessGroup
ProcessName
Charmonium
gg2QQbar[3S1(1)]g, qg2QQbar[3PJ(8)]q, ...
Bottomonium
gg2QQbar[3S1(1)]g, gg2QQbar[3P2(1)]g, ...
Top
gg2ttbar, qqbar2ttbar, qq2tq(t:W),
ffbar2ttbar(s:gmZ), ffbar2tqbar(s:W)
FourthBottom, FourthTop, FourthPair (fourth generation)
HiggsSM
ffbar2H, gg2H, ffbar2HZ, ff2Hff(t:WW), ...
HiggsBSM
h, H and A as above, charged Higgs, pairs
SUSY
qqbar2chi0chi0 (not yet completed)
NewGaugeBoson
ffbar2gmZZprime, ffbar2Wprime, ffbar2R0
LeftRightSymmmetry
ffbar2ZR, ffbar2WR, ffbar2HLHL, ...
LeptoQuark
ql2LQ, qg2LQl, gg2LQLQbar,
qqbar2LQLQbar
ExcitedFermion
dg2dStar, qq2uStarq, qqbar2muStarmu, ...
ExtraDimensionsG*
gg2G*, qqbar2G*, ...
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