University of Saskatchewan  Physics and Engineering Physics

Experimental Subatomic Physics 

Some simple CERN GEANT simulation exercises

By Ru Igarashi and Joss Ives
Note: A new version of both the exercises and associated files was installed on 22 October, 2001. The version below will still be accessible at http://nucleus/Geant/Exercises_old.

The following exercises are intended to introduce new users of GEANT to some of the basic methods of using this simulation package. The files for these exercises can be extracted from To extract them, move to your working directory, and use 'tar -z -x -v -f <filename>'.

The main files of interest are:

gxint.f - sets up the X11 interactive user interface.
uginit.f - calls initialization routines, most importantly UGEOM and UHINIT.
ugeom.f - called by uginit.f, this sets up the geometry of the experiment, the location of volumes, shapes of volumes, and materials in the volumes.
uhinit.f - called by uginit.f, this defines histograms.
gutrev.f -
gukine.f - called at the start of each event, this initializes the kinematics of each event.
gustep.f - called at each step within an event, this would be where tallying would occur for later treatment, and would be for any manipulation of microscopic information in the event.
guout.f - called at the end of each event, this would be where histograms for totals (e.g. energy deposition) would incremented, and would be for any manipulation of macroscopic information about the event.
uglast.f - called at the end of the simulation (or at "exit" of interactive session), this would be where results would be outputted (to files, or to screen).
gxphys.f - ?
Makefile - 'make' script to compile and run the simulation.
view.kumac - a PAW macro file, used to initialize a simulation and set up drawings for track display.
pawlogon.kumac, glogon.kumac - PAW macro files, used by PAW for user customization of a PAW/GEANT session.

The Exercises

Exercise 1: Manipulation of Basic Variables

Exercise 2: Energy Loss Measurement

Exercise 3: Absorption Measurement

Exercise 4: Energy Deposition, etc.

Exercise 5: Change beam direction

Exercise 6: Reducing the acceptance

Exercise 7: Finite beam spot

Exercise 8: Finite beam divergence

Exercise 9: Beam monitor

Index of hints to from all exercises

Main Page

Last updated: 23 Sept 2001