Title: Packages for Monte Carlo simulation of radiation interaction with matter
1Packages for Monte Carlo simulation of radiation
interaction with matter
Sergey Ananko
- Saint-Petersburg State University
- Department of Physics
- Division of Computational Physics
JASS-06
2Outline
- Actuality
- Short description of physical model
- Monte Carlo method
- Geant4
- Fluka
- Comparison of packages
- Conclusions
- Future plans
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3Actuality
- Particular
- Necessity to have several ways of the solution of
the same problem
- General
- Nuclear physics
- High-energy physics
- Cosmic rays
- Neutrino physics
- Medicine
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4Gamma-rays
Physics review
- 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
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5Scattering cross-section
Physics review
- - 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
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6Photoelectrical effect
Physics review
- Photoelectrical effect is a process of gamma
photon absorption by atom of substance -
- - photoelectron energy
- - photon energy
- - binding energy
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7Compton effect
Physics review
- 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
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8Compton effect
Physics review
- - minimal value of scattered
photon energy - - maximum
photoelectron energy
- gamma-quantum scattering angle
- Compton electron scattering angle
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9Pair production
Physics review
- Pair production is a process of generation
electron-positron pair in nucleus or atom
field
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10Total interaction coefficient
Physics review
- 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
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11Total interaction coefficient
Physics review
mass absorption coefficient for air
- linear absorption coefficient
- mass absorption coefficient
- matter density
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12Model
Physics review
Air-filled cubic volume
Detecting plane
Point-like source
Energy and angular distribution of secondary
particles
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13Two approaches
The Monte Carlo Method
- Deterministic methods
- Finite difference method
- Finite element method
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14Model probability estimation
The Monte Carlo Method
- 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
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15Simulation steps
The Monte Carlo Method
- 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
z
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16Variance reduction
The Monte Carlo Method
- Brute-force approach
- Truncation
- Population control
- Splitting
- Russian roulette
- Probability modification
- Pseudodeterministic methods
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17Geometry description
The Monte Carlo Method
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18Monte Carlo packages
The Monte Carlo Method
- 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
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19Geant4 status
GEANT4
- 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
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20Main features
GEANT4
- GEANT4 is written in C
- GEANT4 is based on an object-oriented technology
- Experiment stages
- Detector description
- Source description
- Physics description
- Detector reaction description
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21Fluka status
Fluka
- 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
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22Main features
Fluka
- Fluka is written in Fortran
- Package consists of compiled libraries, user
routing in source form, INCLUDE files, various
unformatted and formatted data and a number of
scripts for compiling, linking and running the
program. - Structure of input file particle source,
geometry, transport options, detectors
Example source (kind of particle, energy,
location in space, distribution) BEAM 50.E00
PROTON BEAMPOS 0.0 0.0
-50.0
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23Comparison main features
Geant4
Fluka
photoelectric effect
Compton effect
- recommended value for threshold for Fluka
pair production
multiple scattering
threshold energy
24Conclusion
- Both Fluka and Geant4 provide with ability of
simulation particles transport in a very extended
energy range.
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25Future plans
- To receive results from Fluka
- To process them
- To compare them with Geant4
- To parallel both Fluka and Geant4
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26