November 18, 1897 - Birth of Patrick Blackett, known for his work on the cloud chamber and cosmic rays

At the end of World War I, he went to study physics with Ernest Rutherford at Cambridge, graduating from Magdalene College (UK) in 1921.

Subsequently, for 10 years, he worked at the Cavendish Laboratory, directed by Rutherford, and began his research with cloud chambers which resulted, in 1924, in the first photographs showing the transmutation of nitrogen into an oxygen isotope, produced by bombarding atomic nuclei with alpha particles.

In 1932, together with the Italian scientist Occhialini, he designed a counter-controlled cloud chamber, a brilliant invention with which they made cosmic rays take their pictures. By this method, the cloud chamber is set in motion only when the impulses from two Geiger-Muller tubes, placed one above and one below Wilson's vertical chamber, coincide as a result of the passage of an electrically charged particle through both.

In 1933 they not only confirmed Anderson's discovery of the positive electron, but also demonstrated the existence of "showers" of positive and negative electrons, both in approximately equal amounts. This fact, and the knowledge that positive particles (positrons) do not normally exist as normal constituents of matter on Earth, formed the basis of their conception that gamma rays can be transformed into two mathematical particles (positrons and electrons) plus a certain amount of kinetic energy, a phenomenon usually called pair production.

In interpreting these experiments, Blackett and Occhialini were guided by the electron theory of physicist Paul Dirac.

In 1933, Blackett became a professor of physics at Birkbeck College in London, where he continued his cosmic ray research work, thus creating a cosmopolitan school of researchers.

In 1937, he succeeded Sir Lawrence Bragg at the University of Manchester, where Bragg had succeeded Rutherford, as chairman of the physics department and his school of cosmic research continued to develop and, since the war, the Manchester laboratory has expanded its field of activity, particularly in the investigation of radar meteor trails, under the direction of Dr. Lovell.

In 1945, after the end of the Second World War, he resumed cosmic ray research at the University of Manchester and, in particular, continued the study of cosmic ray particles using the counterweight-controlled fog chamber in a strong magnetic field, built and used before the war.

In 1948, his work was awarded the Nobel Prize in Physics for his discoveries in the fields of nuclear and cosmic ray physics.

If you want to know more about this scientist, click on the following link: Patrick Blackett