The synchrotron accelerates with an RF field. The RF field is set for a
rotational speed of .999 .9999 .995 or so c.

There are things called coincidence couunters where a particle traveels
through one scintillator and then another. This eliminates the
contributions from radioactive minerals etc. The muon I can assure
everyone goes through a cooincidence counter at c as near as no
matter. A CC can tell the difference between 150c and 0.998c. It cant
really tell the difference between .998c and c, so let us say the muon
travells at c.