The nuclear radii of aluminum and gold are approxi- mately r = 3.6 fm and 7.0 fm, respectively. The radii of protons and alpha particles are 1.3 fm and 2.6 fm, respectively.
(a) What energy a particles would be needed in head-on collisions for the nuclear surfaces to just touch? (This is about where the nuclear force becomes effective.)
(b) What energy protons would be needed? In both (a) and (b), perform the calculation for aluminum and for gold.