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Note Problem with very small stepsize caused by transportation process? 

Keywords: small stepsize, transportation
Forum: Fast Simulation, Transportation & Others
Date: 10 Jan, 2007
From: Henning Gast <Henning Gast>

Hi,

I am simulating a cosmic-ray detector in G4.8.2 and have encountered the following problem:

In some (1/1000) events, there is a very tiny step size in one of my "TrdLayer" volumes, leading to the event being practically stuck, for example: (description continues below)

*********************************************************************************************************
* G4Track Information:   Particle = e-,   Track ID = 391,   Parent ID = 319
*********************************************************************************************************

Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
    0      132      262     -136      2.93        0        0         0 TrdRadiator initStep
    1      134      265     -125      2.81    0.122     11.3      11.3 TrdRadiator msc
    2      134      265     -125       2.8  0.00425    0.535      11.9 TrdRadiator msc
    3      134      265     -125       2.8  0.00012  0.00768      11.9   TrdModule Transportation
    4      135      265     -124       2.8 0.000112     1.35      13.2   TrdModule msc
    5      136      265     -123       2.8 0.000321     1.35      14.6   TrdModule msc
    6      137      265     -122       2.8 8.46e-05     1.35        16   TrdModule msc
    7      137      265     -122       2.8 4.34e-05    0.138      16.1 TrdStrawTubeWall2 Transportation
    8      137      265     -122      2.78   0.0224    0.135      16.2 TrdStrawTubeWall2 msc
    9      137      265     -122      2.75    0.025    0.135      16.4 TrdStrawTubeWall2 msc
   10      137      265     -121      2.74   0.0143    0.075      16.4 TrdStrawTubeWall2 msc
   11      137      265     -121      2.74        0  0.00011      16.4 TrdStrawTubeGas2 Transportation
   12      138      266     -121      2.74 0.000465     1.08      17.5 TrdStrawTubeGas2 msc
   13      139      266     -120      2.74 3.31e-05     1.08      18.6 TrdStrawTubeGas2 msc
   14      140      266     -120      2.74 8.01e-05     1.08      19.7 TrdStrawTubeGas2 msc
   15      141      266     -119      2.74 2.18e-05     1.06      20.7 TrdStrawTubeGas2 msc
   16      141      266     -119      2.74  1.4e-05    0.188      20.9 TrdStrawTubeGas2 msc
   17      141      266     -119      2.74        0   0.0078      20.9 TrdStrawTubeWall2 Transportation
   18      142      266     -119      2.59    0.151     0.28      21.2 TrdStrawTubeWall2 msc
   19      142      266     -119      2.52   0.0693     0.28      21.5 TrdStrawTubeWall2 msc
   20      142      266     -119      2.51  0.00798   0.0414      21.5 TrdStrawTubeGas2 Transportation
   21      145      267     -119      2.51 0.000523     3.56      25.1 TrdStrawTubeGas2 msc
   22      148      269     -120      2.51 0.000431     3.56      28.6 TrdStrawTubeGas2 msc
   23      150      271     -123      2.51 0.000999     3.56      32.2 TrdStrawTubeGas2 msc
   24      151      271     -123      2.51 0.000195    0.529      32.7 TrdStrawTubeWall2 Transportation
   25      151      271     -123       2.5  0.00469   0.0242      32.8 TrdStrawTubeWall2 msc
   26      151      271     -123       2.5  0.00342   0.0242      32.8 TrdStrawTubeWall2 msc
   27      151      271     -123       2.5  0.00262   0.0242      32.8 TrdStrawTubeWall2 msc
   28      151      271     -123      2.49  0.00219    0.017      32.8 TrdStrawTubeWall2 msc
   29      151      271     -123      2.49  3.8e-07 1.72e-06      32.8   TrdModule Transportation
   30      151      271     -123      2.49 0.000203    0.677      33.5   TrdModule msc
   31      151      272     -124      2.49 1.66e-05    0.677      34.2   TrdModule msc
   32      152      272     -124      2.49 2.13e-05    0.677      34.8   TrdModule msc
   33      152      272     -125      2.49 1.75e-05    0.525      35.4 TrdRadiator Transportation
   34      154      278     -132      2.41    0.084      9.2      44.6 TrdRadiator msc
   35      151      282     -139      2.31    0.103      9.2      53.8 TrdRadiator msc
   36      144      286     -143      2.22   0.0882      9.1      62.9 TrdRadiator msc
   37      136      291     -142      2.13   0.0881      9.2      72.1 TrdRadiator msc
   38      129      293     -136      2.05   0.0843      9.2      81.3 TrdRadiator msc
   39      127      297     -128      1.95   0.0997      9.2      90.5 TrdRadiator msc
   40      129      299     -125      1.91   0.0342     4.19      94.7 TrdRadiator msc
   41      130      300     -125       1.9  0.00977    0.987      95.6 TrdRadiator msc
   42      130      300     -125       1.9 0.000779    0.055      95.7 TrdRadiator msc
   43      130      300     -125       1.9 9.59e-07  9.4e-05      95.7   TrdModule Transportation
   44      130      300     -125       1.9        0    0.267        96   TrdModule msc
   45      130      300     -124       1.9        0    0.267      96.2   TrdModule msc
   46      130      300     -124       1.9 9.27e-06   0.0642      96.3 TrdStrawTubeWall7 Transportation
   47      130      300     -124       1.9   0.0062   0.0328      96.3 TrdStrawTubeWall7 msc
   48      130      300     -124      1.89  0.00481   0.0328      96.4 TrdStrawTubeWall7 msc
   49      130      300     -124      1.88   0.0121   0.0328      96.4 TrdStrawTubeWall7 msc
   50      130      300     -124      1.87  0.00599   0.0328      96.4 TrdStrawTubeWall7 msc
   51      130      300     -124      1.87  0.00671   0.0328      96.5 TrdStrawTubeWall7 msc
   52      130      300     -124      1.86  0.00223   0.0102      96.5 TrdStrawTubeWall7 msc
   53      130      300     -124      1.86  4.3e-06 1.93e-05      96.5 TrdStrawTubeGas7 Transportation
   54      130      301     -124      1.86 0.000166    0.436      96.9 TrdStrawTubeGas7 msc
   55      130      301     -124      1.86 0.000733    0.436      97.3 TrdStrawTubeGas7 msc
   56      131      301     -124      1.86 0.000134    0.436      97.8 TrdStrawTubeGas7 msc
   57      131      301     -124      1.86 0.000116    0.162      97.9 TrdStrawTubeGas7 eIoni
   58      131      302     -124      1.86  8.8e-05    0.183      98.1 TrdStrawTubeWall7 Transportation
   59      131      302     -124      1.84   0.0169   0.0992      98.2 TrdStrawTubeWall7 msc
   60      131      302     -124      1.83   0.0147   0.0992      98.3 TrdStrawTubeWall7 msc
   61      131      302     -124      1.81   0.0176   0.0992      98.4 TrdStrawTubeWall7 msc
   62      131      302     -124      1.81  0.00361    0.017      98.4   TrdModule Transportation
   63      131      303     -124      1.81 5.91e-05     0.84      99.3   TrdModule msc
   64      132      303     -124      1.81 0.000893     0.84       100   TrdModule msc
   65      132      304     -123      1.81 4.51e-05     0.67       101   TrdModule msc
   66      132      304     -123      1.81 1.06e-06  0.00734       101 TrdStrawTubeWall8 Transportation
   67      132      304     -123      1.79   0.0139   0.0532       101 TrdStrawTubeWall8 msc
   68      132      304     -123      1.78   0.0129   0.0532       101 TrdStrawTubeWall8 msc
   69      132      304     -123      1.78  0.00086   0.0081       101 TrdStrawTubeWall8 msc
   70      132      304     -123      1.78 9.78e-07  4.4e-06       101 TrdStrawTubeGas8 Transportation
   71      134      306     -124      1.78 0.000717     3.11       104 TrdStrawTubeGas8 msc
   72      135      308     -124      1.78 0.000352     1.57       106 TrdStrawTubeWall8 Transportation
   73      135      308     -124      1.77   0.0134   0.0751       106 TrdStrawTubeWall8 msc
   74      135      308     -124      1.75   0.0148   0.0658       106   TrdModule Transportation
   75      136      308     -124      1.75 6.12e-05    0.917       107   TrdModule msc
   76      136      309     -124      1.75   0.0001    0.917       108   TrdModule msc
   77      136      309     -124      1.75        0     0.22       108 TrdLongStiffener3 Transportation
   78      137      309     -124      1.73   0.0259   0.0991       108 TrdLongStiffener3 msc
   79      137      309     -124      1.68   0.0412   0.0902       108   TrdModule Transportation
   80      137      310     -125      1.68        0    0.574       109   TrdModule msc
   81      137      310     -125      1.68 6.89e-05    0.447       109 TrdRadiator Transportation
   82      143      322     -135      1.47    0.161     16.9       126 TrdRadiator eIoni
   83      141      329     -143      1.33    0.145     11.3       137 TrdRadiator msc
   84      138      331     -144      1.29   0.0385     3.32       141 TrdRadiator msc
   85      135      334     -144      1.25   0.0424     5.04       146 TrdRadiator msc
   86      134      351     -131      1.05    0.197     21.2       167 TrdRadiator msc
   87      137      351     -126     0.998   0.0537     6.19       173 TrdRadiator msc
   88      138      351     -125     0.985   0.0132     1.47       175 TrdRadiator msc
   89      139      351     -125     0.982  0.00315    0.404       175 TrdRadiator msc
   90      139      351     -125     0.982 2.46e-05  0.00647       175   TrdModule Transportation
   91      139      351     -125     0.982 0.000123    0.526       175   TrdModule msc
   92      140      352     -124     0.982 9.75e-06    0.526       176   TrdModule msc
   93      140      352     -124     0.982        0    0.213       176 TrdStrawTubeWall15 Transportation
   94      140      352     -124     0.954   0.0275    0.153       176 TrdStrawTubeWall15 msc
   95      140      352     -124       0.9   0.0538    0.153       177 TrdStrawTubeWall15 msc
   96      140      352     -124     0.887   0.0137   0.0531       177   TrdModule Transportation
   97      140      352     -124     0.887 7.62e-05    0.351       177   TrdModule msc
   98      141      352     -125     0.886 3.12e-05    0.351       177   TrdModule msc
   99      141      352     -125     0.886        0     0.11       177 TrdRadiator Transportation
  100      142      353     -128     0.846   0.0408     4.08       181 TrdRadiator msc
  101      141      352     -132     0.805   0.0406     4.08       186 TrdRadiator msc
  102      139      352     -135     0.763   0.0417     4.08       190 TrdRadiator msc
  103      135      352     -136     0.724   0.0398     4.08       194 TrdRadiator msc
  104      132      352     -134     0.677   0.0468     4.08       198 TrdRadiator msc
  105      130      353     -130      0.63   0.0467     4.08       202 TrdRadiator msc
  106      131      353     -127     0.586   0.0443     4.08       206 TrdRadiator msc
  107      134      353     -126     0.555   0.0303     3.35       209 TrdRadiator msc
  108      136      353     -129     0.513   0.0428     4.08       213 TrdRadiator msc
  109      134      353     -132     0.468   0.0448     2.99       216 TrdRadiator msc
  110      134      353     -132     0.467 0.000904   0.0512       216 TrdRadiator msc
  111      134      354     -132     0.467 3.81e-08 3.16e-06       216    TrdLayer Transportation
  112      128      355     -128     0.466  0.00138     9.91       226    TrdLayer msc
  113      130      356     -125     0.464  0.00111     3.66       230    TrdLayer msc
  114      131      356     -125     0.464  0.00065     1.13       231    TrdLayer msc
  115      131      356     -125     0.464  4.4e-05    0.471       232    TrdLayer msc
  116      131      356     -125     0.464 2.08e-05    0.124       232    TrdLayer Transportation
  117      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  118      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  119      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  120      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  121      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  122      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  123      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  124      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  125      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  126      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  127      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  128      131      356     -125     0.464 7.58e-13 4.58e-09       232    TrdLayer Transportation
  129      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  130      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  131      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  132      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  133      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  134      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  135      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  136      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  137      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  138      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  139      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  140      131      356     -125     0.464 7.58e-13 4.58e-09       232    TrdLayer Transportation
  141      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  142      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  143      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  144      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  145      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  146      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  147      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  148      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  149      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  150      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  151      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  152      131      356     -125     0.464 7.58e-13 4.58e-09       232    TrdLayer Transportation
  153      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  154      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  155      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  156      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  157      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  158      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  159      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation
  160      131      356     -125     0.464 1.66e-13    1e-09       232    TrdLayer Transportation
  161      131      356     -125     0.464 1.69e-13 1.02e-09       232    TrdLayer Transportation

... and so on...

In some events, G4 seems to be able to recognize and amend the situation:

WARNING - G4Navigator::ComputeStep()
          Track stuck, not moving for 10 steps
          in volume -TrdLayer- at point (-9.019548462,-67.04845417,311.976)
          direction: (0.9993687785,0.004953406355,0.03517823564).
          Potential geometry or navigation problem !
          Trying pushing it of 9e-10 mm ...
WARNING - G4Navigator::ComputeStep()
          Track stuck, not moving for 10 steps
          in volume -TrdLayer- at point (-9.019548454,-67.04845417,311.976)
          direction: (0.9993687787,0.004953406355,0.03517823201).
          Potential geometry or navigation problem !
          Trying pushing it of 9e-10 mm ...
... and so on ...

I also attach some output from /tracking/verbose 6 which seems to indicate a problem in the transportation process:

#Step#    X(mm)    Y(mm)    Z(mm) KinE(MeV)  dE(MeV) StepLeng TrackLeng  NextVolume ProcName
 1082    -89.7    -63.5     -285     0.207 1.17e-10 6.93e-09      32.1   TrdModule Transportation

 >>DefinePhysicalStepLength (List of proposed StepLengths): 
    ++ProposedStep(PostStep ) = 1.797693134862316e+308 : ProcName = GammaXTRadiator (No ForceCondition)
    ++ProposedStep(PostStep ) = 1.797693134862316e+308 : ProcName = ElectroNuclear (No ForceCondition)
    ++ProposedStep(PostStep ) = 66843.92633942491 : ProcName = eBrem (No ForceCondition)
    ++ProposedStep(PostStep ) = 43.73431611726596 : ProcName = eIoni (No ForceCondition)
    ++ProposedStep(PostStep ) = 1.797693134862316e+308 : ProcName = msc (Forced)
    ++ProposedStep(PostStep ) = 1.797693134862316e+308 : ProcName = Transportation (Forced)
    ++ProposedStep(AlongStep) = 1.797693134862316e+308 : ProcName = eBrem (CandidateForSelection)
    ++ProposedStep(AlongStep) = 559.1135940543439 : ProcName = eIoni (CandidateForSelection)
    ++ProposedStep(AlongStep) = 0.1951978999090939 : ProcName = msc (CandidateForSelection)
    ++ProposedStep(AlongStep) =         0 : ProcName = Transportation (CandidateForSelection)

 >>AlongStepDoIt (process by process):    Process Name = Transportation

    ++G4Step Information 
      Address of G4Track    : 0xc7b28c8
      Step Length (mm)      : 0
      Energy Deposit (MeV)  : 0
      -----------------------------------------------------------------------
        StepPoint Information               PreStep            PostStep
      -----------------------------------------------------------------------
         Position - x (mm)   :   -89.70796591921498  -89.70796591921498
         Position - y (mm)   :   -63.48666293803226  -63.48666293803226
         Position - z (mm)   :             -285.232            -285.232
         Global Time (ns)    :    4.079087373687271   4.079087373687271
         Local Time (ns)     :   0.1366161237314643  0.1366161237314643
         Proper Time (ns)    :  0.08792145067135242 0.08792145067135242
         Momentum Direct - x :  -0.9805329125797901 -0.9805329125797901
         Momentum Direct - y :   0.1807490143955495  0.1807490143955494
         Momentum Direct - z : -0.07671376110471373-0.07671376110471372
         Momentum - x (MeV/c):  -0.4943958688733998 -0.4943958688733998
         Momentum - y (MeV/c):  0.09113571291042878 0.09113571291042877
         Momentum - z (MeV/c): -0.03867995259447763-0.03867995259447762
         Total Energy (MeV)  :    0.717878242726697   0.717878242726697
         Kinetic Energy (MeV):   0.2068791827266971  0.2068791827266971
         Velocity (mm/ns)    :    210.5632471109914   210.5632471109914
         Volume Name         :            TrdModule           TrdModule
         Safety (mm)         :                    0                   0
         Polarization - x    :                    0                   0
         Polarization - y    :                    0                   0
         Polarization - Z    :                    0                   0
         Weight              :                    1                   1
         Step Status         :           Geom Limit          Geom Limit
         Process defined Step:       Transportation      Transportation
      -----------------------------------------------------------------------
          !Note! Safety of PostStep is only valid after all DoIt invocations.

    ++G4ParticleChange Information 
      -----------------------------------------------
        G4ParticleChange Information  
      -----------------------------------------------
        # of 2ndaries       :                    0
      -----------------------------------------------
        Energy Deposit (MeV):                    0
        Track Status        :                Alive
        True Path Length (mm) :                    0
        Stepping Control      :                    0
        Mass (GeV)   :                    0
        Charge (eplus)   :                    0
        Position - x (mm)   :                -89.7
        Position - y (mm)   :                -63.5
        Position - z (mm)   :                 -285
        Time (ns)           :                 4.08
        Proper Time (ns)    :               0.0879
        Momentum Direct - x :               -0.981
        Momentum Direct - y :                0.181
        Momentum Direct - z :              -0.0767
        Kinetic Energy (MeV):                0.207
        Polarization - x    :                    0
        Polarization - y    :                    0
        Polarization - z    :                    0
        Track Weight      :                    0
        Touchable (pointer) :            0xce40500

    ++List of secondaries generated (x,y,z,kE,t,PID):  No. of secodaries = 0

... and so on ...

The following output is generated by my SteppingAction, for every 100th tiny step:

/tracking/verbose 0
 PROBLEM! 1100 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791823444467 MeV
   Position: (-89.70796597055939,-63.48666292857455,-285.2320000000736)
   Currently in volume TrdModule
 PROBLEM! 1200 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791822041985 MeV
   Position: (-89.70796601061012,-63.48666292118423,-285.2320000002578)
   Currently in volume TrdLayer
 PROBLEM! 1300 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791819313116 MeV
   Position: (-89.70796605944828,-63.48666291218628,-285.2320000004788)
   Currently in volume TrdRadiator
 PROBLEM! 1400 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791815863 MeV
   Position: (-89.70796611145013,-63.48666290259673,-285.2320000001471)
   Currently in volume TrdModule
 PROBLEM! 1500 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791813122284 MeV
   Position: (-89.70796615936021,-63.48666289376921,-285.232000000331)
   Currently in volume TrdLayer
 PROBLEM! 1600 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791810473755 MeV
   Position: (-89.70796620763744,-63.48666288485973,-285.2320000000367)
   Currently in volume TrdRadiator
 PROBLEM! 1700 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791806160801 MeV
   Position: (-89.70796626474066,-63.48666287434693,-285.232000000257)
   Currently in volume TrdModule
 PROBLEM! 1800 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791804162851 MeV
   Position: (-89.70796630829986,-63.48666286632119,-285.2320000004406)
   Currently in volume TrdLayer
 PROBLEM! 1900 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791796872486 MeV
   Position: (-89.70796638370334,-63.4866628524233,-285.2320000001464)
   Currently in volume TrdRadiator
 PROBLEM! 2000 tiny steps for Track ID 24, created by hIoni
   Particle: e- E= 0.2068791794378897 MeV
   Position: (-89.70796643017182,-63.48666284385618,-285.2320000003289)
   Currently in volume TrdModule

The interesting part is the current volume that fluctuates although the position of the particle remains virtually constant. The hierarchy in my geometry is as follows:

TrdLayer
 |
 |__ TrdModule
     |
     |__TrdRadiator (among others)

So, a particle should never really enter a "TrdLayer" volume explicitly because the daughter volume "TrdRadiator" in each "TrdModule" fills the upper part of the layer completely.

My setup contains a homogeneous magnetic field. What also puzzles me is the fact that the minimum stepsize in the G4MagInt_Driver should prevent steps from being as small as I observe them, shouldn't it? The parameters for tracking in the magnetic field are as follows:

 Magnetic field: min epsilon step:   5e-05 mm
 Magnetic field: max epsilon step:   0.001 mm
 Magnetic field: delta one step:     0.01 mm
 Magnetic field: delta intersection: 0.001 mm

Unfortunately, the G4MagInt_Driver doesn't have a Get() for the minimum stepsize, so I assume it is the default value of stepMinimum = 1.0e-2 * mm (see G4ChordFinder). Can this be ignored by the transportation process?

I carefully checked the geometry for volume overlaps.

Any insight would be appreciated,

kind regards

Henning

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1 None: Re: Problem with very small stepsize caused by transportation process?   (Vladimir IVANTCHENKO - 10 Jan, 2007)
1 None: Re: Problem with very small stepsize caused by transportation process?   (Henning Gast - 10 Jan, 2007)
(_ None: Re: Problem with very small stepsize caused by transportation process?   (Henning Gast - 11 Jan, 2007)
2 None: Re: Problem with very small stepsize caused by transportation process?   (John Apostolakis - 11 Jan, 2007)
1 None: Re: Problem with very small stepsize caused by transportation process?   (Henning Gast - 12 Jan, 2007)
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