Som Ganguli is at the Tata Institute of Fundamental Research, Mumbai. He is currently participating in an experiment under preparation for the Large Hadron Collider (LHC) at CERN, Geneva. He has been studying properties of Z and W bosons produced in electron-positron collisions at the Large Electron Positron Collider (LEP). During 1970s and early 1980s he was studying production and decay properties of strange and charm particles using bubble chambers.

The story of the large electron positron collider, in short LEP, is linked intimately with our understanding of nature's fundamental particles and the forces between them. We begin our story by giving a brief account of three great discoveries that completely changed our thinking and started a new field we now call particle physics. These discoveries took place in less than three years during 1895 to 1897: discovery of X-rays by Wilhelm Roentgen in 1895, discovery of radioactivity by Henri Becquerel in 1896 and the identification of cathode rays as electrons, a fundamental constituent of atom by J J Thomson in 1897. It goes without saying that these discoveries were rewarded by giving Nobel Prizes in 1901, 1903 and 1906, respectively. X-rays have provided one of the most powerful tools for investigating the structure of matter, in particular the study of molecules and crystals; it is also an indispensable tool in medical diagnosis. The discovery of the nucleus of an atom in 1911 by Ernest Rutherford was due to the availability of beam of alpha particles from radioactive decays. The discovery of electron has given us electronics, TV picture tubes, etc., which are now part of our day to day life.

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Address for Correspondence
S N Ganguli
Tata Institute of Fundamental Research
Mumbai 400 005, India.