multiple-scattering.md

-Some documentation to implement a Gaussian model for the multiple scattering.
-
-See formulas 27.10:
+Some documentation to implement a Gaussian model for the multiple scattering, see formulas 27.10:
 
 http://pdg.lbl.gov/2005/reviews/passagerpp.pdf
+
+---------------------
+
+Take in account the multiple scattering in the covariance:
+
+[multiple_scattering_covariance.pdf](/uploads/d1774fbc91015bd6bd0f80aa3526b1d0/multiple_scattering_covariance.pdf)
+