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Question Cross Sections used to determine Elastic Scattering 

Forum: Hadronic Processes
Date: 23 Jun, 2011
From: Evan Askanazi <Evan Askanazi>

I have been looking at a lot of the Geant4 source code and I have been looking at the date files read in by Geant4 to use for Elasitc and other kinds of scattering. It is because I need to understand how Geant4 uses the data in order to determine the Elastic Scattering Cross Sections of neutrons in Aluminium and other variosu materials and thus see how Geant4 determines the rate at which Elastic Scattering of neutrons occurs in a given material. I have been looking at given data files, for example, the elastic cross sectiond that Geant4 uses for Aluminium : /geant4.9.4/data/G4NDL3.14/Elastic/CrossSection/13_27_Aluminum . For the Elastic Cross Section files, such as this one, there are a set of three numbers at the top and then a set of columns below it. For 13_27_Aluminum, for example, the data format in geant4 looks like this :

           2
           0
        2306
.100000E-04 0.1414E+01 .130872E-04 0.1414E+01 .161744E-04 0.1414E+01
.223488E-04 0.1414E+01 .346975E-04 0.1414E+01 .470463E-04 0.1414E+01
.593950E-04 0.1414E+01 .840925E-04 0.1414E+01 .108790E-03 0.1414E+01
.158185E-03 0.1414E+01 .207579E-03 0.1414E+01 .306369E-03 0.1414E+01
.405158E-03 0.1414E+01 .602737E-03 0.1414E+01 .800315E-03 0.1414E+01
.119547E-02 0.1414E+01 .159063E-02 0.1414E+01 .238094E-02 0.1414E+01
.317125E-02 0.1414E+01 .475188E-02 0.1414E+01 .633250E-02 0.1414E+01
.949375E-02 0.1414E+01 .126550E-01 0.1414E+01 .189775E-01 0.1414E+01
.253000E-01 0.1414E+01 .381588E-01 0.1414E+01 .510177E-01 0.1414E+01
.767354E-01 0.1414E+01 .102453E+00 0.1414E+01 .128171E+00 0.1414E+01
.179606E+00 0.1414E+01 .231042E+00 0.1414E+01 .333912E+00 0.1414E+01
.436783E+00 0.1414E+01 .642525E+00 0.1414E+01 .848266E+00 0.1413E+01
.125975E+01 0.1413E+01 .167123E+01 0.1413E+01 .249420E+01 0.1413E+01
.331716E+01 0.1413E+01 .496310E+01 0.1413E+01 .660903E+01 0.1413E+01
.990089E+01 0.1413E+01 .131928E+02 0.1413E+01 .197765E+02 0.1413E+01
.263602E+02 0.1413E+01 .395277E+02 0.1413E+01 .526951E+02 0.1412E+01
.790301E+02 0.1412E+01 .105365E+03 0.1411E+01 .158035E+03 0.1410E+01
.210705E+03 0.1409E+01 .316044E+03 0.1407E+01 .421384E+03 0.1405E+01
.570316E+03 0.1402E+01 .719248E+03 0.1399E+01 .101711E+04 0.1392E+01
.154901E+04 0.1381E+01 .202240E+04 0.1371E+01 .244438E+04 0.1361E+01
.282025E+04 0.1353E+01 .315535E+04 0.1345E+01 .345321E+04 0.1339E+01
.371916E+04 0.1333E+01 .395675E+04 0.1327E+01 .416756E+04 0.1323E+01
.435549E+04 0.1319E+01 .452393E+04 0.1315E+01 .467286E+04 0.1312E+01
.480584E+04 0.1310E+01 .492463E+04 0.1309E+01 .503101E+04 0.1308E+01
.512498E+04 0.1308E+01 .520831E+04 0.1309E+01 .528277E+04 0.1311E+01

This is what part of the data format looks like. There is a total of 771 lines worth of data from the 6 columns so this is not all of it but it is part of what the data formal looks like. I was wondering what about what the numbers represent. I had thought that for the six columns the first, third and fifth represent the energy of the particle, in this case the neutron since the neutron is being launched into it. And that the 2nd, 4th and 6th represent the cross sections for a given energy.

Questions are, first off, is that correct, what I assumed above ? What are the units of each of the six columns ? Are the units of the energy values in eV and the units of cross sections, assuming that is what the three sets of columns are, or are different units used ? And also, I noticed that there are 3 numbers in the top, 2, 0 and 2306. What do those numbers represent ?

Thanks for any help anyone can provide.

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1 None: Re: Cross Sections used to determine Elastic Scattering   (Joel Long - 24 Jun, 2011)
(_ Question: Re: Cross Sections used to determine Elastic Scattering   (e askan - 26 Jun, 2011)
(_ None: Re: Cross Sections used to determine Elastic Scattering   (Joel Long - 27 Jun, 2011)
(_ Feedback: Re: Cross Sections used to determine Elastic Scattering   (Evan Askanazi - 27 Jun, 2011)
(_ Feedback: Re: Cross Sections used to determine Elastic Scattering   (Joel Long - 28 Jun, 2011)
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