Calculate accelerating voltage required to separate two particles in a magnetic sector analyser
Baseline separating C-12 from C-13 from C-14 requires accelerator mass spectrometry,

http://en.wikipedia.org/wiki/Accelerator_mass_spectrometry

Your example requires 100 times the finesse.  I'm not optimistic for reduction to practice vs. a paper solution.  Your target could be a charge-coupled device or a channel plate amplifier.  Observe the spatial separation of signals above noise.  A Faraday cup works differently.  Time-of-flight is not optimistic.

You might diddle FT ion cyclotron resonance in a high-Q cavity.