|Message: random velocity generator in G4Nucleus,cc||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
In G4Nucleus the random velocity of a collision partner for a thermal neutron is chosen from a Gausian distribution. This procedure is unrealistic for both solids and gases. The distribution of vibrational states of target atoms in a solid is well explained by the Debye theory of specific heat. In a gas, the speeds and directions of random target atoms (or molecules) should be chosen from a biased Maxwellian flux distribution. In any case, it is essential to account for the variation of the cross section with relative velocity.
While GEANT4 is not heavily used for thermal neutrons, it doesn't make much sense to burden it with inaccurate code. If there is interest in correcting this problem, perhaps I can help.
|Inline Depth:||Outline Depth:||Add message:|