described his 'neutral doublet', or neutron, in 1920.
The particle would be uncharged but with a mass only
slightly greater than the proton. Because it was uncharged
there would be no electrical repulsion of the neutron
as it passed through matter, so it would be much more
penetrating than the proton. This would make the neutron
difficult to detect.
discovery of the neutron was made by James Chadwick,
who spent more than a decade searching. Chadwick had
accompanied Rutherford in his move from Manchester to
Cambridge. He later became the Assistant Director of
Research in the Cavendish, and was responsible for keeping
Rutherford informed of any new developments in physics.
Chadwick and Rutherford often discussed neutrons, and
suggested 'silly' experiments to discover them, but
the inspiration for Chadwick's discovery came from Europe,