( 2 July 1876, Exeter (Canada) - 17 April 1933, Montreal (Canada))
She enrolled in a physics-focused curriculum at McGill University in Montreal, winning several prizes and scholarships that enabled her to continue her studies. She graduated in 1898, at the top of her class in natural philosophy and mathematics.
She was the first graduate student of Ernest Rutherford who directed her work on "Damping of oscillations in the discharge of a Leyden jar". She was the first woman at McGill University to receive a master's degree, in 1901.
After receiving her degree, and under Rutherford's guidance, she conducted a series of experiments to determine the nature of radioactive emissions from thorium, which served as the basis for the development of nuclear science. She was one of the first to determine the atomic mass of radon, which had been discovered in 1900 by Friedrich Ernst Dorn.
Earlier, in 1899, Pierre and Marie Curie had observed that the gas emitted by radium maintained its radioactivity for a month. To them we owe the study of radioactivity and its subsequent development, which found several substances with these properties: radium, polonium… They showed that the intensity of the radiation emitted by each of them was proportional to the amount of uranium present, and so deduced that radioactivity was an atomic property. But what about the energy in the form of radiation or particles emitted by these radioactive elements?
Harriet Brooks, Robert Bowie Owens, and Ernest Rutherford observed variations when trying to measure the radiation from thorium oxide. Rutherford realised that thorium compounds continuously emit a radioactive gas that retains radioactive powers for several minutes. He first called this gas emanation (from the Latin "Emanare"), and then thorium emanation (Th Em).
Brooks focused on the case of thorium (a solid radioactive metal), analysing the emanations of this element. At the time, different theories postulated that this material was a gas, a vapour, or a very fine powder. Brooks showed that it was a gas with a molecular weight significantly lower than that of thorium, so it could not simply be a gaseous form of the same element. Her discovery led Rutherford and other scientists to conclude that with radioactivity, one element had become another. She was the first to characterise the gas we now call radon.
That same year, she moved on a fellowship to Pennsylvania where she won another research grant to go to Cambridge, England, to do successful experiments on radium and thorium, but her self-esteem suffered and she ended up thinking she did not have enough skills to do a PhD, so she returned to McGill University in Canada and started working in the lab with Ernest Rutherford, first on electricity and electromagnetism and then on nuclear physics.
In 1903 she worked with the British physicist J.J. Thompson at the Cavendish Laboratory of Cambridge University.
On 21 July 1904, in a letter to the journal Nature, Harriet Brooks described a peculiar type of volatility shown by an active radium deposit immediately after its emanation had been withdrawn.
In 1904 she began working as a professor at Bernard College, where, in 1904,6 she announced her engagement to a physics professor at Columbia University, which posed a problem for her scientific career, as the dean of Bernard College (an educational institution for women associated with Columbia University) asked her to resign as a professor, as she believed that a woman could not reconcile her marital duties with her academic duties. Brooks broke off her engagement and left Bernard College, spending time in Europe.
In 1906, Brooks worked at the Curie Institute in Paris under the supervision of Marie Curie on the half-life of lead.
In 1907, Ernest Rutherford moved to Victoria University in Manchester where he offered her a position in his laboratory, which she declined because she was engaged to Frank Pitcher, her pre-graduate laboratory instructor, and decided not to combine her married life with her scientific work.
They married in England and returned to Montreal, where she became a wife and mother to their two sons and one daughter, although she never fully disassociated herself from the university. She was honorary secretary and president of the Women's Club of the University of Montreal and, in 1910, presented the work of Marie Curie and her colleagues to the McGill University Alumni Society.
She died on 17 April 1933, at the early age of 56, probably, like her famous colleague Marie Curie, from overexposure to radiation during her lifetime.
An obituary of Harriet Brooks was published by the New York credited her as the "discoverer of the recoil of the radioactive atom." Brooks is considered one of the leading women of her time.
