Vacuum biasing does not produce any interactions in the vacuum

[Former user]

I am unable to get any secondaries produced for arbitrary values of the cross section factor. This definitely used to work for scaling factors on the scale of ~10^14 over the course of ~500 metres. The attached file biased.gmad shows this.

[Laurie Nevay]

Confirmed.

All versions of BDSIM since v0.941 work with biasing when used with Geant4.10.2.p03 but not with Geant4.10.3.p03 so it must be due to an interface change with Geant4.

[Former user]

Shell script for compiling, running and comparing the examples of the two biasing examples BDSIM uses between versions of Geant4.

[Laurie Nevay]

We can only reproduce this in Gaent4.10.3.px. Every other version works fine - I'm not sure this is a bug on our side but on Geant4's.