GEANT4 - folk.uio.nofolk.uio.no/gryt/GEANT4_intro_FYSKJM5920.pdf · • GEANT4 willby’ default’only’include’processes ... • Learning’to’run’GEANT4

GEANT4

A pla+orm for the simula6on of the passage of par6cles through ma:er

FYS-‐KJM5920. Gry M. Tveten, [email protected]





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.



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.




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


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.


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








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








P. Zugec et al, NIM A 760 (2014)





•  Determining the response func;on of a detector / calibra;on



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?


€

(ΔE tot )2 = (ΔEdet )

2 + (ΔE electr )2 + (ΔEbeam )

2 + ...


Unfolding your spectra (OCL data)








What is ”built in” in GEANT4?

(ΔEtot )2 = (ΔEdet )

2 + (ΔEelectr )2 + (ΔEbeam )

2 +...





2 +...





2 +...

Any effect due to the electronics must be modelled by you and programmed!


How to download, install and run


What will your files look like?

Files folder for module src/


How to run an example

h:ps://geant4.web.cern.ch/geant4/UserDocumenta6on/UsersGuides/ForApplica6onDeveloper/html/ch02.html


In the world of MIPs things simplify


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



MODULES MADE FOR OCL


One scin6llator


CACTUS


SiRi


Exercises in GEANT4

•  Learning to run GEANT4 •  Simula6ng gamma-‐rays entering into a large volume LaBr3 scin6llator detector


Documents

GEANT4 - folk.uio.nofolk.uio.no/gryt/GEANT4_intro_FYSKJM5920.pdf · • GEANT4 willby’ default’only’include’processes ... • Learning’to’run’GEANT4