In case this goes equal or below 1 we stop tracking the bunch and integrating 
in the material until we have in minimum more than one particle on all nodes.

Works for one core (obviously) and the regression test Degarder-1, degrades a 72 MeV beam to 50.200 MeV.
This is the current benchmark, to be confirmed by FLUKA simulations. 

There is a new material Mylar (My) avaidable. 

Problems/ToDo:

-- the increase of NP from 100000 to 100072 is certainly non physical
-- check for more than one core
-- validate the regression test
-- validate Mylar parametrization