Pn Scattering Order: Definition & Differences

[Stephan_doc]

I use some computational codes.I must to enter Pn scattering order for some materials.What means that? For example what is difference betwen P1,P2,P3 order?

 

[Astronuc]

I use some computational codes.I must to enter Pn scattering order for some materials.What means that? For example what is difference betwen P1,P2,P3 order?

Assuming one is familiar with discrete ordinates methods and spherical harmonics, the n in P_n refers to the number (n+1) of Legendre polynomials with which one expands the angular flux in transport problems, usually in slab geometry.

See also -
Why are the Pn and Sn Methods Equivalent
https://wci.llnl.gov/codes/tart/media/pdf/UCRL-JC-145518.pdf

krein.unica.it/~cornelis/private/ASTRONOMY/JQSRT/jqsrt71_1_25.pdf

https://eng.ucmerced.edu/people/mmodest/portal/publications/papers/JQSRTv109.pdf

P.R.M Storchi, Application of the Pn-method to the calculation of the anaular flux of gamma rays, Journal of Computational Physics, Volume 55, Issue 1, July 1984, Pages 81-97, ISSN 0021-9991, 10.1016/0021-9991(84)90016-0.
(http://www.sciencedirect.com/science/article/pii/0021999184900160)

 

[raining Pete]

Pn scattering order refers to the number of terms used in a polynomial expansion to approximate the scattering cross section of a material. The higher the Pn order, the more terms are included in the expansion and the more accurate the approximation will be. P1 order means that only the first term (linear term) is used, P2 order means the first two terms (linear and quadratic), and so on for P3, P4, etc. Generally, higher Pn orders are used for more complex materials or when a higher level of accuracy is required.