[904] | 1 | <!-- ******************************************************** --> |
---|
| 2 | <!-- --> |
---|
| 3 | <!-- [History] --> |
---|
| 4 | <!-- 1st version created: Katsuya Amako, Dec-2006 --> |
---|
| 5 | <!-- --> |
---|
| 6 | <!-- ******************************************************** --> |
---|
| 7 | |
---|
| 8 | |
---|
| 9 | <!-- ********************* QandA Section ******************** --> |
---|
| 10 | <section id="qanda.PhysicsCuts"> |
---|
| 11 | <title> |
---|
| 12 | Physics and cuts |
---|
| 13 | </title> |
---|
| 14 | |
---|
| 15 | <qandaset defaultlabel="qanda"> |
---|
| 16 | |
---|
| 17 | <!-- ******* QandA Entry ******** --> |
---|
| 18 | <qandaentry id="qanda.PhysicsCuts.HowProdCuts"> |
---|
| 19 | |
---|
| 20 | <question><para> |
---|
| 21 | How do production cuts (in range) work in Geant4 ? Are they also used |
---|
| 22 | in tracking ? If a particle has an energy lower than the converted cut |
---|
| 23 | in energy for the given material and the distance to the next boundary |
---|
| 24 | is smaller than the cut in range, is the particle killed ? |
---|
| 25 | </para></question> |
---|
| 26 | |
---|
| 27 | <answer><para> |
---|
| 28 | Geant4 does <emphasis role="bold">NOT</emphasis> have a "tracking cut". |
---|
| 29 | The toolkit's default behaviour is to track particles down to zero range |
---|
| 30 | (i.e. zero energy). Of course, it is possible for the user to create and |
---|
| 31 | register a process that kills particles below a certain energy or range; |
---|
| 32 | this is however <emphasis role="bold">NOT</emphasis> provided by default |
---|
| 33 | in Geant4. So there's <emphasis role="bold">NO</emphasis> "tracking cut". |
---|
| 34 | For example, suppose a particle that is nearing zero energy will at some |
---|
| 35 | point be proposed by its Ionisation process to undergo one final step, |
---|
| 36 | from its current energy down to zero energy. This is still only a |
---|
| 37 | proposal. If during this step the particle crosses a boundary, then the |
---|
| 38 | transportation will limit the step at a length smaller than the |
---|
| 39 | Ionisation -- so the particle will still see and cross the relevant |
---|
| 40 | boundary, and another step will occur on the other side of that boundary. |
---|
| 41 | In summary the "production threshold" range and its equivalent in energy |
---|
| 42 | are not utilised as a "tracking cut". A particle is not abandoned by |
---|
| 43 | Geant4 below a certain range/energy unless the user registers a process |
---|
| 44 | to do this by him/her-self. |
---|
| 45 | </para></answer> |
---|
| 46 | |
---|
| 47 | </qandaentry> |
---|
| 48 | |
---|
| 49 | |
---|
| 50 | </qandaset> |
---|
| 51 | </section> |
---|