Rosemary Fowler

Rosemary Fowler ( Brown; born 1926) is a British physicist who in 1948 as a 22-year-old doctoral researcher discovered the kaon (or K meson particle). While studying photographic plates that had been left exposed to cosmic rays, she identified a new configuration of tracks within the photographic emulsion that she recognised as being the decay of an unknown charged particle. Her discovery contributed to the introduction into particle physics of the property of strangeness, and to physicists' understanding that parity is not conserved in weak interactions – features that now form an integral part of the Standard Model of particle physics.

Early life and education Born in Suffolk in 1926, Brown grew up in Malta, Portsmouth and finally Bath, as her family moved to follow the postings of her father, a Royal Naval engineer. At school in wartime Bath, she excelled in maths and science, and was the only girl in her year to go to university. In 1947, she became one of the first women to gain first class honours in physics at the University of Bristol.

Research After graduating from Bristol, Brown became a doctoral researcher in the group of Cecil Powell, a British physicist and pioneer in the use of nuclear emulsion coated plates to investigate cosmic rays entering the Earth's atmosphere. Powell and his team had achieved success with these techniques, and had already discovered a theorised particle, the pi meson or pion.

The "k track" plate showing three-pion decay of a positively-charged kaon. The kaon (k) enters at left and decays into a meson (a) and two mesons (b and c). The meson then interacts with a nucleus in the emulsion at B.

Working alongside her fellow PhD student and future husband Peter Fowler, Brown studied the tracks left on stacks of photographic plates that were exposed to cosmic rays at the Sphinx Observatory, a high-altitude laboratory at Jungfraujoch, Switzerland. When Minnie van der Merwe, one of the team of "scanners" (non-physicist assistants), passed her a plate with an unusual configuration of tracks, Brown recognised it as a candidate for the decay of a new meson, called at that time the 'tau meson' (not to be confused with the entirely different elementary particle currently called the tau). which included a photograph of what became known as the 'k track' plate.

Brown's 'tau meson' appeared similar to the 'theta meson' that had been discovered earlier by G.D. Rochester and C.C. Butler of the University of Manchester, except that it decayed into three pions rather than the two of the 'theta meson'.

Personal life and legacy Rosemary Brown and Peter Fowler married in 1949. She never completed her doctorate, but continued to assist her husband while raising their three daughters Presenting the award, Sir Paul Nurse, Chancellor of the University of Bristol, said "Rosemary's work in particle discovery in the 1940s, as a physicist at Bristol, paved the way for critical discoveries that continue to shape the work of today's physicists, and our understanding of the universe." Dr Fowler said that she felt "very honoured" and that she had not "done any thing since to deserve special respect."

Publications