One of the founding fathers of modern particle physics, George Rochester, has died aged 93. Rochester discovered the kaon – or K-meson – one of the first sub-nuclear particles to be detected besides the neutron and the proton. The breakthrough sparked a rush to find a host of other sub-atomic particles predicted by theory.
In 1947, Rochester and Clifford Butler – a colleague at Manchester University – noticed an unusual pair of tracks in their cloud chamber. The traces could only be explained by the decay of a neutral particle with a mass about 1000 times greater than that of the electron. After the pair repeated their experiment in the French Pyrenees – where the cosmic ray flux is higher – it emerged that the decaying particle was a kaon, a type of meson. Mesons were predicted to exist fleetingly in the nucleus to explain why similarly charged nucleons bind together.
The kaon had unusual properties that physicists at the time dubbed ‘strange’. When quarks were discovered in the 1960s, it became clear that these characteristics arose from a certain quark within the kaon, and this became known as the ‘strange’ quark.
A plethora of new sub-atomic particles was discovered in the years that followed. The development of particle accelerators allowed physicists to study these particles and establish the relationships between them, which have evolved into the modern Standard Model of particle physics.
Rochester was born on Tyneside in 1908 and attended Armstrong College in Newcastle, which was then part of Durham University. After receiving his BSc, MSc and PhD degrees, he carried out postdoctoral research at the University of California before taking up a lectureship at Manchester University. He returned to Durham in 1955 as professor of physics and chair of the department.
Rochester’s involvement in university life continued after his retirement in 1973, and the new physics department that he helped to design opened in 1997. He died on 26 December 2001.
Meanwhile, physicists at Brookhaven National Laboratory in the US announced today the observation of an extremely rare decay event of the kaon. In a sample of hundreds of billions of kaons – generated by the lab’s Alternating Gradient Synchrotron – only two decayed into a pi-meson (or ‘pion’), a neutrino and an antineutrino.
The E787 Collaboration has not detected this event since they first saw it four years ago, on the 50th anniversary of the kaon’s discovery. The results – which could give new insights into the Standard Model of particle physics – are to appear in Physical Review Letters.
