measured masses (14 n) = 2.33*10 -26 kg
measured mass of ( 15n) = 2.46 * 10 -26 kg
For circular motion centripetal force (mv^2 / r) magnetically force (Bqv)
mv^2 / r = Bvr
r = mv^2 / Bq
for N14 :-
r1 = (2.46*10-26) * 513000^2 / 0.510 * 1.6* 10 -19)
for N15:-
r2 = (2.33 *10-26 ) * 513000^2 / 0.510 * 1.6 * 10 -19
so separation is :- 2r2 - 2r1 = 2 ( r2 - r1)