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Particles and interactions

Particles and interactions

100 years of the electron: from discovery to application

07 Apr 1997

Joseph John Thomson – universally known as J J – discovered the electron 100 years ago this month and Physics World celebrates the centenary of the discovery with four articles of different aspects of the first fundamental particle

J J Thomson

Thomson grew up in humble surroundings near Manchester, where his parents had intended him to be an apprentice locomotive maker. But, as Gordon Squires recounts, a university scholarship led J J to Cambridge in 1876, where he made his momentous discovery as professor of the Cavendish Laboratory in 1897.

Thomson was from an era when physicists could afford to ignore the many practical applications of their discoveries, and once proposed the following toast: “Here’s to the electron. May no-one find a use for it”. That, of course, has now all changed. Electron beams, for example, are helping semiconductor multinationals to design integrated circuits that are even tinier than currently possible with light beams, as Lloyd Hariott and Alexander Liddle of Bell Labs explain.

Then there is the ubiquitous electron microscope, which can elucidate crystal structure, and even image and manipulate individual atoms. Ray Egerton from the University of Alberta in Canada describes electron energy-loss spectroscopy, a technique which can characterize interfaces buried deep in sample, and explain how individual atoms in a solid are bound to one another.

But a century after Thomson’s discovery, physicists still do not fully understand the fundamental properties of the electron. Ed Hinds and Ben Sauer from Sussex University in the UK describe the latest experiments to measure the electric dipole moment of the electron. Current theory predicts that it should be immeasurably small, but if the electron does have a dipole moment, we might get a glimpse of new physics that lies beyond the Standard Model that has ruled the sub-atomic world for more than 20 years.

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