Who discovered the spin quantum number?

The Franck-Hertz experiment proves that

Rutherford's $\alpha$-particle experiment showed that the atoms have

The $\alpha$-particle is the nucleus of an atom of

The size of an atom is of the order of:

If an alpha particle with energy $7.7 \text{ MeV}$ is bombarded on a thin gold foil, the closest distance from the nucleus it can reach is . . . . . . $\text{m}$. (Atomic number of gold $= 79$ and $\frac{1}{4 \pi \epsilon_0} = 9 \times 10^9$ in $SI$ units)