|Message: Re: gamma energy spectrum of nGd capture||Not Logged In (login)|
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On Wed, 30 Oct 2013 09:24:27 GMT, G.F. Cao wrote:
> Dear G4-experts, > > Recently, based on Geant4.9.6.p01, I implemented a very simple simulation program and tried to get gamma energy spectrum of neutron captured on Gadolinium. And I found that the total energy of gammas released from nGd capture is not equal to its Q except only one gamma released. For example, the Q value of n-Gd155 capture is 8.536 MeV, but you can see a tail on the figure shown in red line. > > Does anybody know the reason? The last gamma is lost?
Your results can be reproduced with example Hadr03 (histo 11) and macro in attachment. Here physics constructor is FTFT_BERT_HP : plot neutronHP.gif
According the experts, ENDF data set is not designed to preserve energy conservation; there is no guarantee to have it.
However, in neutronHP package, an option goverved by an environment variable (see envHadronic.csh) can be used : plot use_only_photonEvaporation.gif
Alternatively, you can choose another physics component, like INCL or QBBC (see PhysicsList.cc) : plot incl.gif
Attachment: http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/11/01/06.24-93501-guofu.mac.txt http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/11/01/06.24-42565-neutronHP.gif http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/11/01/06.24-84813-nly_photonEvaporation.gif http://hypernews.slac.stanford.edu/HyperNews/geant4/get/AUX/2013/11/01/06.24-75804-incl.gif