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Packages for Monte Carlo simulation of radiation interaction with matter. Sergey Ananko. Saint-Petersburg State University Department of Physics Division of Computational Physics. JASS-06. Outline. Actuality Short description of physical model Monte Carlo method Geant4 Fluka

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packages for monte carlo simulation of radiation interaction with matter

Packages for Monte Carlo simulation of radiation interaction with matter

Sergey Ananko

Saint-Petersburg State University

Department of Physics

Division of Computational Physics

JASS-06

outline
Outline
  • Actuality
  • Short description of physical model
  • Monte Carlo method
  • Geant4
  • Fluka
  • Comparison of packages
  • Conclusions
  • Future plans

JASS-06

actuality
General

Nuclear physics

High-energy physics

Cosmic rays

Neutrino physics

Medicine

Particular

Necessity to have several ways of the solution of the same problem

Actuality

JASS-06

gamma rays

Physics review

Gamma-rays

Gamma-rays – high-frequency electromagnetic oscillations: and above

Gamma-particles characteristics:

velocity:

energy:

momentum:

wave length:

Gamma photons energy range:

Effects: photoelectrical absorption, Compton effect and pair production

JASS-06

scattering cross section

Physics review

Scattering cross-section

- number of photons through unit square per unit of time

- number of scattered photons

- cross-section

- number of scattered gamma photons

- probability

of photons scattering

JASS-06

photoelectrical effect

Physics review

Photoelectrical effect

Photoelectrical effect is a process of gamma photon absorption by atom of substance

- photoelectron energy

- photon energy

- binding energy

JASS-06

compton effect

Physics review

Compton effect

Compton effect is a process of gamma photon scattering on electron of atom

- scattered photon energy - incident photon energy

- electron rest-energy

- wave length after interaction - wave length before interaction

- Compton electron energy

JASS-06

compton effect1

Physics review

Compton effect

- minimal value of scattered photon energy

- maximum photoelectron energy

- gamma-quantum

scattering angle

- Compton electron

scattering angle

JASS-06

pair production

Physics review

Pair production

Pair production is a process of generation electron-positron pair in nucleus or atom field

JASS-06

total interaction coefficient

Physics review

Total interaction coefficient

Number of photons lost by the beam:

where

- cross-sections of Compton effect, photo effect, pair production

- atom number per unit of volume

- flux density

- beam cross-section

- total interaction cross-section per one atom of matter

Quantum energy loss per unit of time:

JASS-06

total interaction coefficient1

Physics review

Total interaction coefficient

mass absorption coefficient for air

- linear absorption coefficient

- mass absorption coefficient

- matter density

JASS-06

model

Physics review

Model

Air-filled

cubic volume:

Detecting plane

Gamma energy range:

Point-like source

Energy and angular distribution of secondary particles

JASS-06

two approaches
Deterministic methods

Finite difference method

Finite element method

The Monte Carlo method

The Monte Carlo Method

Two approaches

JASS-06

model probability estimation

The Monte Carlo Method

Model: probability estimation
  • Source – anisotropic point-like monoenergetic gamma photon source
  • Shield – relatively thick spherical shell, only one sort of atom
  • Effects:
        • Elastic scattering
        • Absorption
  • Effects are characterized by:
  • Cross-section
  • Probability density function for path length

JASS-06

simulation steps
First step: free path length

Second step: scattering or absorption

Third step: scattering angle

Further steps: repeating

- number of generated trajectories

- number of escaped gamma photons

- score

Estimated probability of escape:

Variance of the :

Relative error

The Monte Carlo Method

Simulation steps

z

JASS-06

variance reduction

The Monte Carlo Method

Variance reduction
  • Brute-force approach
  • Truncation
  • Population control:
  • Splitting
  • Russian roulette
  • Probability modification
  • Pseudodeterministic methods

JASS-06

geometry description
Combinatorial object

Surface-sense object

The Monte Carlo Method

Geometry description

JASS-06

monte carlo packages

The Monte Carlo Method

Monte Carlo packages
  • Main components:
  • Data base of cross-sections and other parameters
  • Theoretical base
  • Random number generator
  • Tool for geometry description
  • Main aspirations:
  • Extended range of ability
  • Flexibility
  • Examples:

MNCP, Fluka, Geant, Geant4, Vulcanu, PYTHIA, ARIADNE and so on

JASS-06

geant4 status

GEANT4

Geant4: status

Geant4 is a detector description and simulation tool

Application areas:

High-energy physics, nuclear experiment, medical, accelerator and space physics studies

History:

1974 – GEANT first version

1982 – the appearance of GEANT3

1998 December – first release of GEANT4

Geant4 is a free software

It can be downloaded from URL:

http://geant4.cern.ch

Operating systems:

Unix, Linux, Windows

JASS-06

main features

GEANT4

Main features

GEANT4 is written in C++

GEANT4 is based on an object-oriented technology

Experiment stages:

  • Detector description
  • Source description
  • Physics description
  • Detector reaction description

JASS-06

fluka status

Fluka

Fluka: status

Fluka is a general purpose tool for calculations of particle transport and interactions with matter, covering an extended range of applications spanning from proton and electron accelerator shielding to target design, calorimetry, activation, dosimetry, detector design, Accelerator Driven Systems, cosmic rays, neutrino physics, radiotherapy etc.

Fluka is distributed under the licence as a tar file

It can be downloaded from its web-site:

www.fluka.org

Supported platforms:

  • - Hewlett-Packard 9000 Series 700/800 running HP-UX
  • - Sun running SunOS
  • - Intel PCs running LINUX:
  • - RedHat 7.3
  • - RedHat 9.0
  • - Scientific Linux 4.1 `
  • - Fedora Core

History:

First generation – the Fluka of the 70th

Second generation – the Fluka of the 80th

Third generation – the Fluka of today

JASS-06

main features1

Fluka

Main features

Fluka is written in Fortran

Package consists of compiled libraries, user routing in source form, INCLUDE files, various unformatted and formatted data andanumberofscriptsforcompiling,linkingandrunningtheprogram.

Structure of input file: particle source, geometry, transport options, detectors

Example: source (kind of particle, energy, location in space, distribution)

BEAM 50.E+00 PROTON

BEAMPOS 0.0 0.0 -50.0

JASS-06

comparison main features
Comparison: main features

Geant4

Fluka

photoelectric effect:

Compton effect:

- recommended value for threshold for Fluka

pair production:

multiple scattering:

threshold energy

conclusion
Conclusion

Both Fluka and Geant4 provide with ability of simulation particles transport in a very extended energy range.

JASS-06

future plans
Future plans
  • To receive results from Fluka
  • To process them
  • To compare them with Geant4
  • To parallel both Fluka and Geant4

JASS-06