In scattering experiment, find distance of closest approach if a 6 MeV alpha particle is used
2. The attempt at a solution
initially KE of alpha particle is 6 x 10^6 x e joules and 0 PE, finally its PE is kq1q2/d, k=9 x 10^9, q1=4e, q2=Ze=79e (assuming gold), d is distance of closest approach, e is charge on electron. Plugging in the values gives an incorrect answer. The correct answer (far from it) is 2 x 10^(-14) m. Is there a mistake I'm making?