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Forum: Hadronic Processes
Re: Question neutron stimulated gamma spectrum (Tuoyu Cao)
Date: 17 Jan, 2013
From: michel maire <michel maire>

On Tue, 15 Jan 2013 02:47:56 GMT, Tuoyu Cao wrote:
> Hi All,
> 
> I had simulated the characteristic gamma spectrum from neutron inelastic
> scattering. I shoot 2.5 MeV neutron beam to water Iron mixture cube
> (1cm3). The Iron concentration is very small, about 60 ppm. I can get
> about 20 gammas on 847keV peak from 1 million incident neutron. However
> after I add other elements to the mixture, for example 60 ppm Cu, the
> number of gammas on the Iron peak decreases a lot. In other words, the
> precence of other elements (even very small amount), can affect neutron
> scattering cross section of Iron. I don't understand the mechanism here
> and I am not sure if the result makes sense. Thanks a lot for any
> explanation.
> 

 Playing with example Hadr03 (and QBBC physics), one get following informations:
 cross section n + Fe56 : 0.96 barn
 cross section n + Cu63 : 1.24 barn, eg. the same order of magnitude.

 Therefore, in a mixture Fe-Cu (50%-50%), about half of neutron beam will interact with Cu instead of Fe, as it can be seen in the attached log file.
 I also attach plot of gamma spectrum (low and high energy parts)  

   Attachment:
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/17/08.50-58404-Fe_Cu.log.txt
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/17/08.50-7406-gamma1.gif
      http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/01/17/08.50-57577-gamma2.gif

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1 Question: Re: neutron stimulated gamma spectrum   (Tuoyu Cao - 17 Jan, 2013)
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