Penning trap and vacuum noise
A number of comments are provided on Rogers's model experiment to measure the circular Unruh vacuum noise by means of a hyperbolic Penning trap inside a microwave cavity. It is suggested that cylindrical Penning traps, being geometrically simpler, and controlled almost at the same level of accuracy as the hyperbolic trap, might be a better choice for such an experiment. Besides, the microwave modes of the trap itself, of known analytical structure, can be directly used in trying to obtain measurable results for such a tiny noise effect.