Now head of Cambridge University's nuclear physics lab, Rutherford oversaw Chadwick's PhD in 1921 and then made him assistant director of the lab. Chadwick's own research focused on radioactivity.

In 1913, Niels Bohr revised Rutherford's model by suggesting that the electrons ... The proton had been proposed as being the nuclear particle responsible for the positive charge of the nucleus ...

This view of the atomic nucleus changed when James Chadwick discovered the existence ... enough energy to "view" this substructure. "In our model, we made improvements to simulate the phenomenon ...

Now head of Cambridge University's nuclear physics lab, Rutherford oversaw Chadwick's PhD in 1921 and then made him assistant director of the lab. Chadwick's own research focused on radioactivity.