Problem 231

Summary: Bad neutron behavior in ExN03
Product: Examples/Basic and Novice Reporter: will
Component: N03Assignee: Michel.Maire
Status: RESOLVED INVALID    
Severity: normal CC: will
Priority: P2    
Version: 3.0   
Hardware: PC   
OS: Linux   

Description will 2001-03-19 14:47:51 CET
I am trying to do modelling using neutrons with this example.  I made a small
modification to ExN03DetectorConstruction.cc to add extra molecule types.  The
problem is this:  neutron paths don't seem to be correctly modeled.  For any
kind of absorber/gap material types, neutrons seem to go straight through.  As
far as I can tell, other particles work properly, e.g. alpha particles, protons,
muons, electrons, and positrons.
This occurred when I entered the commands in interactive mode:
/gun/particle neutron
/gun/energy 14 MeV
/run/beamOn 25
This gives straight lines in all cases where the gun particle that was used is
a neutron.  It really doesn't matter what absorber/gap material is used, even
for molecules specified by the original ExN03DetectorConstruction.cc.  I noticed
an interesting and obviously wrong behavior by setting the run & tracking output
to verbose.  The neutron's energy seems to never get initialized (i.e. it is at
zero before and after all the runs are executed).  Unfortunately, I don't know
enough about Geant's architecture yet to understand where the problem might be.
I can provide additional information, e.g. output from exampleN03 binary,
screenshots of output, etc.
Comment 1 Michel.Maire 2001-03-21 04:21:59 CET
PhysicsList of N02 and N03 contain only so called 'electromagnetic processes'.
For neutron-nucleus interactions, see N04 physics list