|Message: Re: neutron stimulated gamma spectrum||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)|
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
|Inline Depth:||Outline Depth:||Add message:|