Server Physics

Options
I'm implementing an authoritative Photon Server and I need some basic physics features for now: raycasts, collision with triggers (no gravity, bouncing, or position correction, just knowing when they overlap).

Can anyone recommend any physics library they have used? or any that they think would work well? If possible a very basic, very fast physics library, but any suggestions would be appreciated.

I've searched previous posts but they are quite old and have almost no answers.
Thanks