In a Rutherford scattering experiment, alpha particles of kinetic energy E E\,E are fired head-on at a target nucleus of proton number ZZZ. The closest distance of approach for this head-on collision is ddd, as shown in the diagram below.
In a second experiment, alpha particles of kinetic energy 1.6E 1.6E\,1.6E are fired head-on at a target nucleus of proton number 1.2Z1.2Z1.2Z.
What is the closest distance of approach for this second experiment in terms of ddd?
0.52d0.52d0.52d
0.75d0.75d0.75d
1.33d1.33d1.33d
1.92d1.92d1.92d
