Electrons in air, what happens at 100 keV?

I am shooting electrons following a 14C beta source distribution.
The electrons pass through few mm of airs and are then scored in a scoring region filled with vacuum to check the energy of the electrons surviving up to there.
When I plot the results, for a certain travelled thickness of air, I obtain the picture in attachment.
In the beginning I thought it was more a binning issue, but the discontinuity seems to be always at 100 keV. Is because of a change in the physics model, pls? I use the Livermore one.

I ran example Hadr06 with attached macro (belloni.mac), and different electromagnetic constructors (see PhysicsList.cc). The plot below is with G4EmLivermorePhysics.
1- e- at creation, eg. as generated by radioactive decay process.
2- e- emerging out of a sphere of 1.5 mm of air.
3- superposition.

Other Em constructors gives similar results. I do not see any anomaly around 100 keV.

belloni.mac.txt (522 Bytes)

I am going to relook at it.