Problem 221

Summary: propagation of a particle in a uniform electric field (Geant4 2.0)
Product: Geant4 Reporter: lagouri
Component: geometry/magneticfieldAssignee: John Apostolakis <John.Apostolakis>
Status: RESOLVED FIXED    
Severity: normal    
Priority: P2    
Version: 2.0   
Hardware: PC   
OS: Linux   

Description lagouri 2001-02-19 11:59:06 CET
I have similar problems as in the reported problem no.138 in the case of a
uniform electric field (3 V)
a)Trying to propagate neutrons of 0.2 eV
G4PropagatorInField::ComputeStep   ERROR : attempting a zero step= 1.83599e-15
 and/or no progress after 11 trial steps.  ABORTING.
G4PropagatorInField::ComputeStep No progress - Looping with zero steps

*** G4Exception: Aborting execution ***
Aborted
b)Trying  to propagate electrons of 2 MeV (I would like to mention that in the
case of lower energy electrons of the order of eV there is no this kind of
problem)

* G4Track Information:   Particle = e-,   Track ID = 1,   Parent ID = 0
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng
NextVolume ProcName
    0         0               0              1
2                     0                   0             0
chamber         initStep
    1      -7.33          200           1
2                     0.000386     200          200
World            Transportation
 Warning (G4MagIntegratorDriver): The stepsize for the  next
iteration=1.2795e-14 is too small - in Step number 1.
     Requested step size was 255.899 .
     Previous  step size was 255.899 .
     The minimum for the driver is 0.01
     The integrations has already gone 2.55899e-15


G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    2    -8.09      207     1.04         2        0     7.35       208
World           Transportation
G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    3    -8.32      209     1.05         2        0     2.19       210
World           Transportation
G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    4     -8.8      214     1.07         2        0     4.48       214
World           Transportation
G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    5     -8.8      214     1.07         2        0 2.56e-11       214
World           Transportation
G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    6     -8.8      214     1.07         2        0 2.56e-11       214
World           Transportation
G4PropagateInField: Warning: Particle is looping -  tracking in field
will be stopped.
 It has performed 10000 steps in Field  while a maximum of 10000 are
allowed.
    7     -8.8      214     1.07         2        0 2.56e-11       214
World           Transportation
    8     -8.8      214     1.07         2        0 1.28e-15       214
World           Transportation
    9     -8.8      214     1.07         2        0  6.4e-16       214
World           Transportation
   10     -8.8      214     1.07         2        0  1.6e-16       214
World           Transportation
   11     -8.8      214     1.07         2        0    4e-17       214
World           Transportation
   12     -8.8      214     1.07         2        0    1e-17       214
World           Transportation
   13     -8.8      214     1.07         2        0  2.5e-18       214
World           Transportation
   14     -8.8      214     1.07         2        0 6.25e-19       214
World           Transportation
   15     -8.8      214     1.07         2        0 1.56e-19       214
World           Transportation
 G4PropagatorInField::ComputeStep   ERROR : attempting a zero step=
3.90444e-20
 and/or no progress after 11 trial steps.  ABORTING.
G4PropagatorInField::ComputeStep No progress - Looping with zero steps

*** G4Exception: Aborting execution ***
Aborted
Comment 1 Gabriele Cosmo 2001-02-20 01:17:59 CET
*** Bug 138 has been marked as a duplicate of this bug. ***
*** 'John.Apostolakis@cern.ch' will be responsible for bug 138. ***
Comment 2 Gabriele Cosmo 2001-04-11 07:04:59 CEST
Could you please try out release 3.1 ?
Rather important fixes and improvements have been applied to the
mag-field module and transportation in this new release.
Let us know if you still notice any problem.
Thanks.
Comment 3 John Apostolakis 2002-04-17 08:41:59 CEST
We have verified that our fixes, published in Geant4 4.0, have corrected the
errors that we were able to reproduce.