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Forum: Event and Track Management
Re: Question tracking problem? (Dennis Haggerty)
Date: 18 Oct, 2007
From: Vladimir IVANTCHENKO <vnivanch@mail.cern.ch>

On Thu, 18 Oct 2007, Dennis Haggerty wrote:

> *** Discussion title: Event and Track Management
> Email replies to PublicHyperNews@slac.stanford.edu must include:
>   In-Reply-To: <"/eventtrackmanage/722"@geant4-hn.slac.stanford.edu>
>   Subject: ...change this to be about your reply.
> 
> Iím having what I think is a tracking problem. Iím running a very simple
> shield simulation using G4Box. When I run electrons into the material
> sometimes they come out of the material and then reenter the material. I
> have two slabs, the first is very thin with material set to Vacuum. The
> second slab is WCu (but I get the same thing if I use a pure Al slab).
> There is no energy loss in this process. I also get the same answer if I
> use the first slab and set the second slab to Vacuum. I cannot figure
> out what is turning them around. I'm running 4.9.0.p01
> 
> Note step 25 in the tracking log below.
> 
> Any suggestions?
> 
> Regards,
> 
> Dennis
> 
> *********************************************************************************************************
> * G4Track Information:   Particle = e-,   Track ID = 1,   Parent ID = 0
> *********************************************************************************************************
> 
> Step#      X         Y         Z        KineE    dEStep   StepLeng  TrakLeng    Volume     Process
>     0     -5 cm   -2.2 Ang   5.3 Ang  1.47 MeV     0 eV      0 fm      0 fm        Layer    initStep
>     1 -5e+03 fm   -2.2 Ang   5.3 Ang  1.47 MeV     0 eV      5 cm      5 cm        Layer  Transportation
>     2  5e+03 fm   -2.2 Ang   5.3 Ang  1.47 MeV     0 eV  1e+04 fm      5 cm           D1  Transportation
>     3   1.73 mm   -2.2 Ang   5.3 Ang  1.47 MeV     0 eV   1.73 mm   5.17 cm        Layer  Transportation
>     4   1.75 mm  -2.54 um  -5.46 um   1.44 MeV  26.9 keV  19.2 um   5.17 cm           D2         msc
>     5   1.75 mm  -1.06 um  -5.37 um   1.42 MeV  4.08 keV  3.41 um   5.18 cm           D2   LowEnBrem
>     6   1.76 mm     12 um   -107 nm    1.4 MeV  20.9 keV  19.2 um   5.18 cm           D2         msc
>     7   1.77 mm   17.2 um   3.79 um   1.37 MeV  10.6 keV  8.71 um   5.18 cm           D2  LowEnergyIoni
>     8   1.77 mm   19.8 um   10.3 um   1.35 MeV  8.06 keV  8.08 um   5.18 cm           D2   LowEnBrem
>     9   1.78 mm   33.7 um   16.7 um   1.32 MeV  26.3 keV  19.2 um   5.18 cm           D2         msc
>    10    1.8 mm     39 um   24.2 um   1.31 MeV  11.3 keV  19.2 um   5.18 cm           D2         msc
>    11   1.81 mm     52 um     21 um   1.29 MeV  27.5 keV  19.2 um   5.18 cm           D2         msc
>    12   1.81 mm   69.1 um   27.2 um   1.26 MeV  22.4 keV  19.2 um   5.19 cm           D2         msc
>    13   1.81 mm     87 um   26.9 um   1.24 MeV  23.7 keV  19.2 um   5.19 cm           D2         msc
>    14   1.82 mm    103 um     34 um   1.21 MeV  33.6 keV  19.2 um   5.19 cm           D2         msc
>    15   1.83 mm    110 um   40.1 um   1.19 MeV  19.3 keV  19.2 um   5.19 cm           D2         msc
>    16   1.85 mm    121 um   38.9 um   1.16 MeV  21.6 keV  19.2 um   5.19 cm           D2         msc
>    17   1.86 mm    137 um   37.5 um   1.14 MeV  28.2 keV  19.2 um    5.2 cm           D2         msc
>    18   1.85 mm    146 um   25.4 um   1.11 MeV  24.4 keV  19.2 um    5.2 cm           D2         msc
>    19   1.82 mm    142 um   26.2 um   1.07 MeV  37.1 keV  25.4 um    5.2 cm           D2         msc
>    20   1.81 mm    159 um     22 um   1.05 MeV    27 keV  25.4 um    5.2 cm           D2         msc
>    21   1.79 mm    168 um   18.3 um  1e+03 keV  48.4 keV  25.4 um   5.21 cm           D2         msc
>    22   1.76 mm    168 um   21.8 um    973 keV  26.4 keV  25.4 um   5.21 cm           D2         msc
>    23   1.74 mm    162 um   30.7 um    940 keV  33.1 keV  25.4 um   5.21 cm           D2         msc
>    24   1.73 mm    160 um   41.7 um    912 keV  28.4 keV  23.5 um   5.21 cm           D2  Transportation
>    25   1.73 mm    160 um   41.7 um    912 keV     0 eV      0 fm   5.21 cm        Layer  Transportation
>    26   1.73 mm    162 um   48.7 um    879 keV  8.49 keV  8.01 um   5.21 cm           D2  LowEnergyIoni
>    27   1.73 mm    163 um   49.9 um    878 keV  1.36 keV  1.38 um   5.21 cm           D2  Transportation
>    28  5e+03 fm   2.01 mm   4.96 mm    878 keV     0 eV   5.52 mm   5.77 cm        Layer  Transportation
>    29 -5e+03 fm   2.01 mm   4.96 mm    878 keV     0 eV 3.19e+04 fm   5.77 cm           D1  Transportation
>    30  -17.4 cm   18.8 cm     50 cm    878 keV     0 eV   55.7 cm   61.5 cm        Layer  Transportation
>    31  -17.6 cm     19 cm   50.5 cm    878 keV     0 eV   5.63 mm     62 cm   Calorimeter  Transportation
>    32  -17.8 cm   19.2 cm     51 cm    878 keV     0 eV   5.63 mm   62.6 cm   OutOfWorld  Transportation
> 

Hello,

First, you need to confirm that the same happens with standard physics, 

Second, there is a probability for e- to have such big scattering angle at 
the last step near the boundary, that e- does not leave the box. For today 
we need an extra zero-step to resolve this situation.

This situation may be connected with Physics Lists used. Whihc one was 
chosen?

VI

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