You can see the radiation thickness of the detector at definite positions and the radiation thickness of most of the superlayers for a given geometry version if you click below.
Beginning from versions 99.1015 and 0.0903 the mean values are obtained from minimum bias event which are traced with switching off the magnetic field and all types of interactions and energy losses.
Note that all volumes which do not belong to one of the listed superlayers (vessel endcup, beampipe etc) are taken into account only in "radiation length at different positions", but not in individual superlayers.
Whenever a track touches only vaccum or air within one superlayer it will no give contributions to the radiation length - thus rl = 0 contributions will be avoided

GEOM/VERS 2.1205
GEOM/VERS 2.0903
GEOM/VERS 2.0103
GEOM/VERS 1.1116
GEOM/VERS 99.1015
GEOM/VERS 0.0903
GEOM/VERS 0.0813
GEOM/VERS 0.0812
GEOM/VERS 0.0811
GEOM/VERS 0.0810
Siegmund Nowak
July 28. 2000