| 1 | <!-- ******************************************************** -->
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| 2 | <!-- -->
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| 3 | <!-- [History] -->
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| 4 | <!-- 1st version created: Katsuya Amako, Dec-2006 -->
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| 5 | <!-- -->
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| 6 | <!-- ******************************************************** -->
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| 7 |
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| 8 |
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| 9 | <!-- ********************* QandA Section ******************** -->
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| 10 | <section id="qanda.PhysicsCuts">
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| 11 | <title>
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| 12 | Physics and cuts
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| 13 | </title>
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| 14 |
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| 15 | <qandaset defaultlabel="qanda">
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| 16 |
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| 17 |
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| 18 | <!-- ******* QandA Entry ******** -->
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| 19 | <qandaentry id="qanda.PhysicsCuts.HowProdCuts">
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| 20 |
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| 21 | <question><para>
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| 22 | How do production cuts (in range) work in Geant4 ? Are they also used
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| 23 | in tracking ? If a particle has an energy lower than the converted cut
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| 24 | in energy for the given material and the distance to the next boundary
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| 25 | is smaller than the cut in range, is the particle killed ?
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| 26 | </para></question>
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| 27 |
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| 28 | <answer><para>
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| 29 | Geant4 does <emphasis role="bold">NOT</emphasis> have a "tracking cut".
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| 30 | The toolkit's default behaviour is to track particles down to zero range
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| 31 | (i.e. zero energy). Of course, it is possible for the user to create and
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| 32 | register a process that kills particles below a certain energy or range;
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| 33 | this is however <emphasis role="bold">NOT</emphasis> provided by default
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| 34 | in Geant4. So there's <emphasis role="bold">NO</emphasis> "tracking cut".
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| 35 | For example, suppose a particle that is nearing zero energy will at some
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| 36 | point be proposed by its Ionisation process to undergo one final step,
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| 37 | from its current energy down to zero energy. This is still only a
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| 38 | proposal. If during this step the particle crosses a boundary, then the
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| 39 | transportation will limit the step at a length smaller than the
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| 40 | Ionisation -- so the particle will still see and cross the relevant
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| 41 | boundary, and another step will occur on the other side of that boundary.
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| 42 | In summary the "production threshold" range and its equivalent in energy
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| 43 | are not utilised as a "tracking cut". A particle is not abandoned by
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| 44 | Geant4 below a certain range/energy unless the user registers a process
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| 45 | to do this by him/her-self.
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| 46 | </para></answer>
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| 47 |
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| 48 | </qandaentry>
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| 49 |
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| 50 |
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| 51 | </qandaset>
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| 52 | </section>
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