Help me to solve this physics question.(spatial separation)?

Question

Two isotopes of carbon, carbon-12 and carbon-13, have masses of 19.93 multiplied by 10-27 kg and 21.59multiplied by 10-27 kg, respectively. These two isotopes are singly ionized (+e) and each is given a speed of 6.13 105 m/s. The ions then enter the bending region of a mass spectrometer where the magnetic field is 0.6800 T. Determine the spatial separation between the two isotopes after they have traveled through a half-circle.

answers are appreciated..

thank you

Answer 1

use the equation r= mv/(qb)

Then find the difference between the diameters not the radii