The Copley Medal is awarded to Sir James Chadwick for his pioneering researches on the constitution of matter.
Sir James Chadwick was in turn the pupil, the collaborator, and the colleague of Rutherford, basking for a time in the warmth of the radiation from the master and then showing that he possessed fires of his own. It is recognized throughout the world that his leadership in nuclear physics has played a most important part in the sensational developments of sub-atomic science in the last few years.
In the early days he was the first to find the continuous spectrum of beta rays and the first to make an accurate measurement of the charge on the nucleus.
During the First World War he contrived to prosecute some work under the difficult conditions of Ruthleben, and on returning to England joined Rutherford in significant developments of the latter's discovery of the transmutation of nitrogen brought about by alpha rays. He showed that a similar decomposition of the atoms of most of the lighter elements could be effected. These experiments led to his discovery of nuclear resonances.
But the greatest achievement of Sir James, and the one that ensures that the name of Chadwick can only be temporarily and partly lost in his present dignity as Master of Gonvill and Caius College, was his demonstration of the existence of the neutron.
This discovery is transcended in importance only by the that of the electron, and it has revolutionized our conceptions of the structure of the atomic nucleus. It has also proved to be essential for the modern developments of the artificial transmutation of the elements, and all devices for the production of atomic energy are based on the release of neutrons in chain processes.
During the Second World War, Sir James took a leading part in the scientific direction of research, while his powers of organization, gifts of nuclear leadership and ambassadorial tact were of the utmost value in promoting efficient and harmonious collaboration in there international sphere.
A brilliant experimenter and a sound, but not a highly speculative philosopher, Chadwick has made contributions to physics and chemistry which are fundamental over the whole range of physical sciences.