Harriet Brooks
Pioneering Researcher in Radioactivity
Brooks was born in Ontario, Canada, on July 2, 1876. Her father was a salesman who moved his large family frequently during Brooks’s school years. Without encouragement from her family, Brooks decided to go to McGill University, Montreal, in 1894 to gain a teaching diploma. This unconventional decision was one of the few ways she could leave home without marrying and gain some financial independence.
McGill University did admit women but provided separate classrooms and instructors for them during the first two years of trader graduate coursework. Brooks graduated with honors, obtaining her teaching diploma in 1898. She then joined the research group of physicist ERNEST RUTHERFORD, who discovered the atomic nucleus, at McGill; she was his first graduate student. She completed research on electricity and magnetism that earned her a master’s degree in physics in 1901.
Brooks began work with radioactive materials in 1899. She identified one of the products of thorium’s decay as a heavy gas (radon), leading Rutherford and Frederick Soddy to the realization that transmutation of that element had occurred.
Brooks continued to explore radioactivity while she held a series of short term positions at Bryn Mawr College (19011902), the Cavendish Laboratory, England, under J. J. Thompson (19021903), McGill University (19031904), Barnard College (19041906), and Laboratoire Curie, Paris (19061907) with Marie Curie.
Brooks made the first measurements of the half life of thorium, and she tracked small electric charges that radioactive materials induced. She also demonstrated that radiation emitted from several natural substances was composed of identical high energy beta particles (electrons) regardless of their source.
In 1904 she published two major papers in nuclear physics. “A Volatile Product from Radium” described her observation that when radium decays to radon and then to polonium, walls of the testing vessel become radioactive. She was the first to record this recoil effect of nuclear radiation. The second paper, “Decay of Excited Radioactivity from Thorium, Radium, and Actinium,” demonstrated that at least two successive transmutations are typical of the decay of the named elements before they reach a stable state (lead).
Brooks lost her teaching position at Barnard College in 1906 when she announced her engagement. “The dignity of women’s place in the home demands that your marriage shall be a resignation,” Dean Gill wrote. When she married Frank Pitcher of Montreal in 1907, Brooks abandoned her search for professional employment.
Brooks died in Montreal of leukemia on April 17, 1933.
Harriet Brooks‘s Legacy
Brooks’s research was fundamental to understanding the sequence of events in radioactivity.
Her contributions focused on radon gas and the elements naturally following from its decay. Brooks’s identification of radon as a separate element, not a volatile form of thorium, was the pioneering step that led to Rutherford and Soddy’s startling assumption in 1902 that transmutation of one element into another lighter element must have occurred. In his papers and public lectures, Rutherford repeatedly gave credit to Brooks for her vital work. He was recognized as a Nobel laureate in 1908 for the breakthrough in the understanding of matter that her studies in radioactivity made possible.
Her demonstration that radiation emitted the same beta particles from several different substances pointed to the existence of electrons. This type of evidence fired NIELS BOHR’s imagination in the 1910s as he developed a new model of atomic structure.
Brooks’s other legacy rests in her position as a woman in science. Marriage or career at lowest wages in academia were the only obvious choices for a woman without independent income, yet Brooks made important contributions in the positions she was able to secure.
Harriet Brooks – 1876-1933