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Forum: Hadronic Processes
Re: Question Bertini Model cross section tables (Juan Pablo Velasquez)
Re: None Re: Bertini Model cross section tables (Juan Pablo Velasquez)
Date: 01 Apr, 2012
From: Michael H. Kelsey <Michael H. Kelsey>

On Sat, 31 Mar 2012 01:16:36 GMT, Juan Pablo Velasquez wrote:
> I would like to vary the cross section values in a percentage and see
> how this affects the propagation of the intra-nuclear cascade. In order
> to estimate an educated variation, It would be very helpful to know what
> the errors looks like.

I see. The derivation of those values long pre-dates my involvement; I'm looking for details on what you've requested. The tabulated values are taken essentially from the old (1970's era) CERN books of evaluated cross-sections for various hadrons on nucleons.

In the mean time, I'm not sure you're going to see any clear effect on cascades due to varying any individual "cross-section" value -- there are separate values for each tabulated final state (with multiplicities from 2 up to 8 or 9), in a couple of dozen bins of projectile kinetic energy.

The cascade propagation is most likely to be affected by varying the grand total cross-section (summed over all final-states) for a given projectile and kinetic energy. That value is used to compute an effective "mean free path" in each nuclear-potential zone (see G4NucleiModel::GenerateInteractionPartners), which is exponentiated and compared to a random throw.

For the pi-N interactions, the totals are tabulated separately in the tables I mentioned previously; for the K-N and hyperon-N interactions, the totals are computed as the sum of exclusive states.

-- Michael Kelsey

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