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On Tue, 07 Jul 2015 18:57:25 GMT, Steve Quillin wrote:
> Hello > > I'm trying to simulate some publicised data on spallation and have made > a simple Geant4 application that fires 1 GeV protons into a 10 cm > uranium sphere and counts the numbers of neutrons emitted. My problem is > with the material definition: results seem to be dependant on the order > in which I add isotopes to an element. > > My material definitions and the results of "printing" them are attached > below. All 3 materials appear identical apart from the isotope order, > yet the neutron multiplicity is smaller by a factor of ~2 (geometry > dependant) when the target sphere is built from Uranium_b than the > others. The fraction of protons that generate neutrons is the same for > all materials. > > Have I made an error in the material definitions or is there something > else going on? > > I'm using geant4-10-01-patch-01 multithreaded with QGSP_BIC and other > physics lists. >
I ran example Hadr03 with the 2 Uranium definitions. I attach macro and extract of outputs (which are big, at 1 GeV) The number of generated neutrons are close, althrough not exactly the same. (spectrum in attachment)
I do not know how much is signifiant this difference of behaviour between the 2 material definitions.
Attachment: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/07/09/07.05-5690-quillin.mac.txt http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/07/09/07.05-97750-u_nist.out.txt http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/07/09/07.05-77337-u_b.out.txt http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2015/07/09/07.05-16262-uranium.gif
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