|Message: Differences in the Binary Cascade Model||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 2011 I did shielding calculation with geant4-09-05-beta-01, physics list QGSP_BIC_HP 1.3. Now I repeat the calculation with geant4-10-02-patch-01, QGSP_BIC_HP 2.0. I use a proton beam with 4.7 GeV.
Behind a shielding of 3 m soil (density 1.8 g/cm3) I observe a large difference between the two geant versions. The neutron and photon flux in the transverse direction is for the new version a factor 10 higher.
For a proton beam with 19 MeV there is no difference. At 100 MeV the difference is large but smaller then at 4.7 GeV. I did the calculation with and without importance sampling and I observed the same difference between the two geant versions.
I guess the difference comes from changes in the BIC-model. Of course, a difference in the cross section of a view per cent adds up to around a factor 2 for 1 m soil and a factor 10 for 3 m soil.
My question is what was changed in the BIC-model and why?
Beyond 9.5 GeV there was a change in the model between the two versions (LEP -> FTF) but my proton energy is well below 9.5 GeV. Therefore this change should not affect my result.
Thank you for an answer, Uli