Neutrinos are funny class of particle, actually as a practical example of Einsteins famous equation ,on the linear accelerators we have a flight tube with an electron source at one end, the electrons get accelerated via a microwave field and reach 98% of the speed of light about half way along the flight tube, then for the rest of the journey along the tube they don't accelerate much but increase in mass until they plop out of the end of the fight tube