From Andrei: 1. TGeoMaterial.cxx (geom.diff) : radiation length is systematically computed in TGeo whenever a material is created (using G3 formula) except for negative values where the absolute value is taken (G3 behavior). There are only ~5 materials in MUON that are defined with negative radlen - all others are positive e.g. ignored by G3/TGeo. TGeo will store a valid (and the same) radiation length whatever MC is used. This is not the case for the absorbtion length, because the algorithm used by G3 to compute it is quite complex and I do not know if it worth copying it in TGeo (anyway as far as I understood is not used in reconstruction)
From Andrei:
1. TGeoMaterial.cxx (geom.diff) : radiation length is systematically computed in
TGeo whenever a material is created (using G3 formula) except for negative
values where the absolute value is taken (G3 behavior). There are only ~5
materials in MUON that are defined with negative radlen - all others are
positive e.g. ignored by G3/TGeo.
TGeo will store a valid (and the same) radiation length whatever MC is used.
This is not the case for the absorbtion length, because the algorithm used by G3
to compute it is quite complex and I do not know if it worth copying it in TGeo
(anyway as far as I understood is not used in reconstruction)


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