|Message: Getting wrong cross section using HP 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)|
Greetings Geant4 community,|
I am using the ParaFission model with HP cross sections to study neutron induced fission in U-238. The cross section for a 15 MeV neutron in the G4NDL file (Fission/CrossSection/92_238_Uranium) is 1.234624 barn. However when I count the number of fission events and calculate the cross section I get a 36% higher cross section. I have also reproduced the problem for the capture reaction so it is not only fission that is affected.
My setup is simple, I shoot 15 MeV neutrons at a 1 um thick U238 target and count the number of events where the primary particle produces fission fragments (in the nCapture case I checked for production of U239).
Below is a list of the things I have tried so far:
1) Change target width.
2) Change target to U235.
3) Edited and changed the cross sections in the G4NDL file.
4) Used 2, 5, 10, 12 and 17 MeV neutrons instead.
5) Inactivated the nInelastic process.
There seems to be a very slight energy dependence but it is very small with no apparent pattern. All other test have ended up with a 36% larger cross section than is found in the G4NDL file.
I have also checked the mean value of the physical interaction length calculated by the process. It has the correct value of 1/([atomic density][G4NDL cross section]).
I use Geant4.9.6 and G4NDL4.2.
I am happy to receive any suggestions of what I could do to track down what is wrong with my simulations.
|Inline Depth:||Outline Depth:||Add message:|