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GEANT4
A pla+orm for the simula6on of the passage of par6cles through ma:er
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
GEANT4
• Download from geant4.cern.ch • Read installa6on instruc6ons for your OS carefully
• GEANT4 is not a program, but rather a pla+orm for crea6ng your own simula6ons
• Refs: Nuclear Instruments and Methods in Physics Research A 506 (2003) 250-‐303, and IEEE Transac6ons on Nuclear Science 53 No. 1 (2006) 270-‐278.
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
GEANT4 is …
• modular. You choose what to include. • flexible. It has been used for a large range of applica6ons.
• based upon evaluated data libraries and closed expressions.
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
GEANT4 is Monte Carlo based
• Repeated random sampling • Well suited for random
processes
"Pi 30K" by CaitlinJo -‐ Own workThis mathema;cal image was created with Mathema;ca. Licensed under CC BY 3.0 via Wikimedia Commons -‐ hGp://commons.wikimedia.org/wiki/File:Pi_30K.gif#/media/File:Pi_30K.gif
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
The characteris6cs of a high quality Monte Carlo simula6on (Sawilowsky) • a good (pseudo-‐random) number generator • The number generator produces values that pass tests for randomness
• there are enough samples to ensure accurate results
• the proper sampling technique is used • the algorithm used is valid for what is being modeled it simulates the phenomenon in ques6on.
Sawilowsky, Shlomo S. (2003). "You think you've got trivials?". Journal of Modern Applied Sta6s6cal Methods 2 (1): 218–225.
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Typical applica6ons for GEANT4
• Planning experiments (where complicated geometries are involved)
• Understanding the background in an experiment
• Determining the response func6on of a detector / calibra6on
• Designing your detectors
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Typical applica6ons for GEANT4
• Planning experiments (where complicated geometries are involved)
• Understanding the background in an experiment
• Determining the response func6on of a detector / calibra6on
• Designing your detectors
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Laser ON
Laser OFF
How thick target can I use? How many coincidence do I need to see the peaks I’m interested in? Figures from MINIBALL@REX-‐ISOLDE
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Typical applica6ons for GEANT4
• Planning experiments (where complicated geometries are involved)
• Understanding the background in an experiment
• Determining the response func6on of a detector / calibra6on
• Designing your detectors
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Typical applica6ons for GEANT4
• Planning experiments (where complicated geometries are involved)
• Understanding the background in an experiment
• Determining the response func;on of a detector / calibra;on
• Designing your detectors
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Example: Photoneutron experiment at NewSUBARU D. M. Filipescu et al (including Therese and Hilde), PRC 90, 064616 (2014) Given a certain photon distribu6on, what is the response of the detector?
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
€
(ΔE tot )2 = (ΔEdet )
2 + (ΔE electr )2 + (ΔEbeam )
2 + ...
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
Typical applica6ons for GEANT4
• Planning experiments (where complicated geometries are involved)
• Understanding the background in an experiment
• Determining the response func6on of a detector / calibra6on
• Designing your detectors
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
What is ”built in” in GEANT4?
(ΔEtot )2 = (ΔEdet )
2 + (ΔEelectr )2 + (ΔEbeam )
2 +...
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
What is ”built in” in GEANT4?
(ΔEtot )2 = (ΔEdet )
2 + (ΔEelectr )2 + (ΔEbeam )
2 +...
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
What is ”built in” in GEANT4?
(ΔEtot )2 = (ΔEdet )
2 + (ΔEelectr )2 + (ΔEbeam )
2 +...
Any effect due to the electronics must be modelled by you and programmed!
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
What will your files look like?
Files folder for module src/
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
How to run an example
h:ps://geant4.web.cern.ch/geant4/UserDocumenta6on/UsersGuides/ForApplica6onDeveloper/html/ch02.html
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
MIPs and what we do
• GEANT4 will by default only include processes relevant for high energy physics
• MIPs are simpler and the calcula6ons are faster
• For low energy nuclear physics you must specify what processes to include
FYS-‐KJM5920. Gry M. Tveten, g.m.tveten@fys.uio.no
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