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WHAT(4) = printing flag: from 0.0 to 3.0 increases the amount of output about cross-sections, kerma factors, etc. Default: 0.0 (minimum output)However, the information is given in a form that is difficult to understand unless one is familiar with multigroup neutron transport codes. Anyway, one will get a table of which a few lines are reproduced here:
1 CROSS SECTIONS FOR MEDIA 1 (RESIDUAL NUCLEI INFORMATIONS AVAILABLE) GROUP SIGT SIGST PNUP PNABS GAMGEN NU*FIS EDEP DOWNSCATTER MATRIX barn barn (PNEL PXN PFISS PNGAM) GeV/col 1 5.826E+00 9.287E+00 .0000 1.5939 1.2904 .3886 1.536E-02 .3228 .0079 .0021 .0023 .0020 .0013 .0011 .0035 ....................................................................... 26 6.861E+00 6.697E+00 .0000 .9761 1.0609 .0181 1.458E-03 .......................................................................Explanation of the relevant quantities:
Group 1 (the highest): Total cross section (SIGT) = 5.826E+00 barn "Scattering" cross. s. (SIGST) = 9.287E+00 barn Probability of Non Absorption (PNABS) = 1.5939 Group 26 : Total cross section (SIGT) = 6.861E+00 barn "Scattering" cross. s. (SIGST) = 6.697E+00 barn Probability of Non Absorption (PNABS) = .9761The data for the first groups will probably look strange (scattering cross section larger than total cross section): the reason is that there is neutron production through (n,xn) reactions (fission is accounted for separately), and here "scattering" means "number of outgoing neutrons times cross section" or also "changing energy group". Since more than one neutron on average is exiting a collision, the probability of non absorption is larger than 1.
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d(Flux(r))/dt = D*\Delta2(Flux(r)) + S(r) - \Sigma_abs*Flux(r)where S(r) term describing the sources and \Sigma_abs the absorption cross section.
dFlux(r)/dt = -[outflow rate] + [production rate] - [absorption rate]and for a steady state solution
[outflow rate] = [production rate] - [absorption rate] = neutron balanceThe particle 8=neutron is scoring the neutron fluence, the quantity most frequently used for describing neutron fields. Fluence is defined as the number of particles that penetrate a sphere with a cross section of pi*r^2 = 1cm2 per unit of time and/or energy. Otherwise, the particles crossing a surface of 1cm2 that is ALWAYS perpendicular to the direction of the particle.
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LOW-BIAS 1.0 0.0 Reg1 Reg2no neutron transport below 500.0 MeV
PART-THR -0.5 NEUTRON
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Last updated: 26th of April, 2016