st. petersburg state university. department of physics. division of computational physics
DESCRIPTION
St. Petersburg State University. Department of Physics. Division of Computational Physics. COMPUTER SIMULATION OF CURRENT PRODUCED BY PULSE OF HARD RADIATION Vadim V. Galitsyn. JASS, 2006. Contents. - Introduction - Actuality - Solution method - Results. JASS, 2006. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
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St. Petersburg State University.Department of Physics.Division of Computational Physics.
COMPUTER SIMULATION OF CURRENT PRODUCED BY PULSE
OF HARD RADIATION
Vadim V. Galitsyn
JASS, 2006
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Contents
- Introduction- Actuality- Solution method- Results
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Introduction
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The aim of this work is to determine the role of a different physical processes for the formation of a current pulse produced by a hard radiation with a initial gamma energy between 20 keV and 4 MeV. It is necessary for better understanding of detector registration efficiency.
Relativistic electrons Speed of light of the current propagation in the detector Secondary physical processes effect
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Actuality
Examples:
- ALICE- ATLAS- LHCb- Future CBM
The actuality is in a possible upgrade of detectors of relativistic charged particles.
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GEANT4 toolkit
We consider to simulate interaction of particles and passage through matter with a GEANT4 Software package
GEANT4 is an open source toolkit for the simulation of the passage of particles through a matter written on C++
Official GEAN4 web site, http://geant4.cern.ch
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How it worksStep 1 of 4. The Volume Space
Physical Volume.
The matter.
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We used Air and Water matter to simulate gamma passage through.
There are many different volume forms possible to create with the GEANT4.
Cubical geometry of a detector was considered.
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How it worksStep 2 of 4. Gamma source and detection plane
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Setting up:
● Gamma beam direction
● Number of gamma
● Gamma energy (between 20 keV and 4 MeV energy range)
● Fixing detection virtual plane position (perpendicular to gamma direction)
Gamma source
Physical Volume.
The matter.
Detection plane
* We were interested by time distribution of secondary electrons at the detection plane and role of the different physical processes for current pulse formation
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How it worksStep 3 of 4. Physics
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Before we run the simulation we must to determine which physical processes we want to see and what particles are we working with
Processes:Photo effect, Compton scattering, Pairing effect
Particles:Gamma, Electron, Positron
Gamma source
Physical Volume.
The matter.
Detection plane
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How it worksStep 4 of 4. Experiment start-up
GEANT4 graphical output window
● GEANT4 show experiment parameters on the screen; we can see particles tracks online
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How it worksWhat we are looking for?
All processes
Current pulse form on detection plane. 1.5 MeV gamma source. Water.
Compton Scattering
Ionization EffectJASS, 2006
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Computer cluster
From 30 minutes to several hours needed to perform calculations for one run consisting of 107 events
We are using high performance clusters for simulations
In our case (full data parallelism) speedup depends linearly on computing nodes (theoretical limit of the Amhdal’s law)
Linearspeedup
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Results (Water)
Passage of gamma quanta through2 mm water layer
4000
The role of different processes in current pulse formation in water
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Results (Air)The role of a different processes in current pulse formation in the air
Passage of gamma quanta through 1 m air layer at atmosphere pressure
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Results
Photo electric effect Compton Scattering Pairing effect
Air
Theory
GEANT4
20 keV
120 keV
Water55 keV
87 keV
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Conclusions
• The role of different physical processes for the formation of current pulse was defined
• The differences between a theory and experiment was detected
• The forms of a current produced by a pulse of hard radiation were defined
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Appendix
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Acknowledgement
S. A. Nemnugin
F. F. Valiev
S. U. Slavyanov
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Thank you for attention
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