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Forum: Hadronic Processes
Re: None Wrong branching ratio in Boron-10 neutron capture (Andrew Erlandson)
Re: None Re: Wrong branching ratio in Boron-10 neutron capture (michel maire)
Date: 21 Feb, 2014
From: Andrew Erlandson <Andrew Erlandson>

On Fri, 21 Feb 2014 11:17:47 GMT, michel maire wrote:
> On Thu, 20 Feb 2014 20:36:47 GMT, Andrew Erlandson wrote:
> 
> > I'm trying to verify to the hadronic physics processes for a boron lined
> > neutron detector but I'm coming up with a problem. The dominant decay
> > from thermal neutron capture on boron-10 should be alpha(1.47MeV) +
> > Li7(0.84MeV) at 94% but I never see this process occuring. Instead, I
> > see only the suppressed decay channel where the reaction produces
> > alpha(1.78MeV) + Li7(1.01MeV) which is supposed to only occur 6% of the
> > time.
> > 
> > This is important because I'm working to characterize the response of
> > gas filled detectors where signals are proportional to dE/dx and as it
> > stands 2 possible signal variations are not occuring. The energy loss in
> > the gas volume seems to be occuring as expected at least.
> > 
> > I'm using geant4.9.4p02 with the GNDL4.2 data libraries. I'm also using
> > the QGSP_BERT_HP physics list to cover the hadronic stuff.
> > 
> > I'm thinking there's either a subtle issue with either the GNDL data or
> > the way I've defined my neutron capture material but I've varied the
> > material definition and implementation and the results are always the
> > same.
> > 
> > Any ideas are appreciated!
> > 
> 
>  I ran Hadr03 with attached macro.
>  Also attached: log file and plots for alpha and Li7
> 
>    Attachment:
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/02/21/03.16-54264-andrew.mac.txt
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/02/21/03.16-71149-andrew.log.txt
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/02/21/03.16-44287-alpha.gif
>       http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2014/02/21/03.16-24740-Li7.gif
> 

Those are the exact results I'd expect. I've tried my code on another PC with the same version of geant and data files and it produces the correct branching ratios... I think there might have been a problem with my install of geant though I can't really seem to find other areas where BR or Xsection results are wrong other than this low energy neutron stuff.

Very strange but thanks for the verification!

Andrew

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