Blackett graduated from Magdalene College with a B.A. in 1921 and continued working for Rutherford for another ten years. In 1923 he became a fellow at Kings College and in 1924 he used a cloud chamber to record the transmutation of nitrogen into oxygen. A cloud chamber is a closed chamber saturated with water or alcohol vapor. When ionizing particles (alpha particles for example) are introduced they create ions. The vapor in the chamber condenses on these ions and the condensed liquid shows the path of the particle through the chamber. While in the Cavendish Laboratory Blackett used a cloud chamber to do experiements involving cosmic rays. From 1924 to 1925 he worked in the laboratories of James Franck in Gottingen, Germany studying atomic spectra. In 1932, working with Italian physicist Giuseppe Occhialini, he developed a cloud chamber with a geiger counter to trigger the camera.
In 1933 he became professor at Birkback College, at the University of London. Also in 1933 he confirmed Carl David Anderson's discovery of the positron. A positron is a positively charged electron, an anti-matter particle. Blackett also worked on annihilation, the collision of matter and anti-matter that produces gamma radiation. In 1937 he became the Longworthy professor at Victoria University in Manchester. While there he worked on a theory of the earth magnetism, hoping to use it to unify the forces of gravity and magnetism. Although he was unsuccessful his work led to the development of paleomagnetism, which was used to prove the existence of continental drift.
In 1935 he was invited to serve on the Tizard Committee, which recommended the installation of radar for air defense. During World War II he served on various defense committees and contributed to the invention of the Mark XIV bomb sight. In 1940 he was awarded the Royal Medal by the Royal Society. In 1948 he was awarded the Nobel Prize for his work on particle physics using cloud chambers. He was appointed chairman of the physics department of Imperial College at London in 1953 and he retired in 1963. Blackett served as an adviser to the post war Labor government and in 1964, at his advice, set up the Ministry of Science and Technology. Blackett was outspoken politically and frequently came under criticism for his socialist and anti-nuclear weapon views.
He died on July 13, 1974.
Brown, Matt; "Patrick Blackett: From Cosmic Rays to International Development"; November 18, 2007; London Blog at blogs.nature.com
Nye, Mary Jo; Blackett: Physics, War and Politics in the 20th Century; Harvard University Press; 2004
Patrick Blackett Nobel Biography
Patrick Blackett Wikipedia Entry