Details about radii expansion method in yade

Hi,

I use the radii expansion method implemented in yade for sample preparation, as given in [1], in which I set internalCompaction=True (If true the confining pressure is generated by growing particles).

It would be good to know more details about this method in Yade, for instance:
1. Do particles (sphere in my case) grow up (scale up) by its radius or volume?
2. During the process of reaching the target confining pressure, do particle monotonically grow up? Or it switch between size up and size down when approaching the target confining pressure? I imagine that if the current confining pressure is larger than the target after one step of growing, then it might be a size down in the next step. Not sure whether I understood correctly.
3. Could you please share me where I can find the source code of radii expansion method implemented in yade?
4. Currently I cite Yade there in my manuscript because it is implemented in Yade. It would be good if there is a specific paper then I can cite together.

Thanks!
Leonard

[1]https://gitlab.com/yade-dev/trunk/blob/master/examples/triax-tutorial/script-session1.py