1. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Use Monte Carlo to simulate geometries and detectors
What is Monte Carlo?
What is Geant4?
Geant4 exercises
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

2. Where you can find these slides
Pablo Cirrone and Enrico Mazzaglia (Geant4 Developers) ( )
Official Geant4 web pages:
Hadrontherapy example:
You will find these slides here:
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

3. The Monte Carlo method I
Is a mathematical approach that use a sequence of random number to solve a problem
If we are interested in a parameter of, i.e., an equation: we must construct a big number of this equations, using different random numbers, and estimate the parameter and its variance A. F. Bielajew, 2001
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

4. The Monte Carlo method II
In particle transport, if the models of particle interaction with matter are known, you can use the MC to calculate the parameters of motion equations in a given configuration
Particles are tracked one-by-one and, after a reasonable number, the correct information is extracted
MC is very time consuming but …..
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

5. The Monte Carlo method III
Mathematical proofs exist demonstrating that MC is the most efficient way of estimate quantity in 3D when compared to first-order deterministic method
Alex F Bielajew, 2001
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

6. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
With MANIAC: the first electronic digital computer
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

7. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Monte Carlo codes
MCNP
Penelope
PETRA
PHIT
FLUKA
Geant4
Geometry And Traking
GEANT4-a simulation toolkit Nucl. Inst. And Methods Phys. Res. A, 506:250:303
Geant4 developments and applications Transaction on Nuclear Science 53,
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

8. Geant4: www.cern.ch/geant4
C++ language
Object Oriented
Open source
It is a toolkit i.e. a collection of tools that the User can use for his/her simulations
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: many examples are provided
Novice Examples: overview of Geant4 tools
Advanced Examples: Geant4 tools in real-life applications
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

9. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Geant4 basic concepts
What you MUST do:
Describe your experimental set-up
Provide the primary particles input to your simulation
Decide which particles and physics 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 your simulation
To visualise your simulation configuration or results
To produce histograms, tuples etc. to be further analysed
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

10. User Classes - I Mandatory classes in ANY Geant4 User Application
G4VUserDetectorConstruction
describe the experimental set-up
G4VUserPhysicsList
select the physics you want to activate
G4VUserPrimaryGeneratorAction
generate primary events
Mandatory classes in ANY Geant4 User Application
A lot of PHYSICS MODELS in a very big range:
from 10 eV to 20 TeV
Electromagnetic
Decay processes
Hadronic elastic
Hadronic inelastic
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

11. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
User Classes - II
Action classes
Invoked during the execution loop
G4VUserPrimaryGeneratorAction
G4UserRunAction
G4UserEventAction
G4UserTrackingAction
G4UserStackingAction
G4UserSteppingAction
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

12. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
The main() program
Geant4 does not provide the main()
Geant4 is a toolkit!
The main() is part of the user application
In his/her main(), the user must
construct G4RunManager (or his/her own derived class)
notify the G4RunManager mandatory user classes derived from
G4VUserDetectorConstruction
G4VUserPhysicsList
G4VUserPrimaryGeneratorAction
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

13. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Geant4 applications I
ATLAS
LHCb
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

14. Geant4 applications II Gamma camera with collimators
Linear accelerator
LSO/LuYAP ClearPET prototype design
3-head SPECT
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

15. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Geant4 installation
Download the source file from the official Geant4 web pages
Download the external libraries
Download and compile the CLHEP
Configure the environment variables of your system
Compile Geant4
Start compiling and running an example
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

16. G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy
Our excercises
Will be based on the Hadrontherapy example
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy

17. The geometry of Hadrontherapy
(HadrontherapyDetectorConstruction.cc)
(ProtonPassiveBeamLine.cc)
G.A.P.Cirrone, S.E.Mazzaglia - INFN/LNS, Italy