Rosemary Fowler

Rosemary Fowler (née Brown) (born 1926) is a British physicist who was instrumental in the discovery of the kaon (or K meson particle). In 1949, 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.

Early life and education
In 1947, she became one of the first women to gain first class honours in physics at the University of Bristol.

Research
On graduating, 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.



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 particle, called at that time the 'tau meson' (not to be confused with the entirely different elementary particle currently called the tau). The group published their findings in a 1949 paper in Nature which included a photograph of what became known as the "k track" plate, now known to show the three-pion decay mode of a charged K meson or kaon.

Brown's work contributed to Powell’s Nobel Prize for Physics in 1950, awarded "for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method."

Awards
In 2024 Fowler was awarded an honorary doctorate by the University of Bristol. The university stated "Rosemary’s discovery of particles and contribution to our understanding of fundamental interactions in physics has often been attributed to Powell and her husband Peter Fowler, and this honorary degree acknowledges the vital role she has played in science."

Personal life
Rosemary Brown and Peter Fowler married in 1949. She never completed her doctorate, but continued to assist her husband while raising their three daughters – one of whom, the geophysicist Mary Fowler, became Master of Darwin College, Cambridge.