The following constants may be useful:

Electron mass = me = 9.1 x 10-31 kg; mec2 = 0.511 MeV

Proton mass = mp = 1.673 x 10-27 kg; mpc2 = 938.28 MeV

Neutron mass = mn = 1.675 x 10-27 kg; mnc2 = 939.57 MeV

Planck's constant = h = 6.63 x 10-34 Js;    hc = 1240 eV nm

speed of light c = 3 x 10 8 m/s      1fm=10-15m