Chadwick had discovered the neutron in February 1932. Two months later John Cockroft and Ernest Walton, encouraged by Rutherford and by George Gamow, a protégé of Bohr’s, managed to induce nuclear disintegration by bombarding lithium nuclei with accelerated protons. This would be the old Cavendish Lab’s last Nobel Prize-winning physics experiment. Within months, Lawrence had replicated their result with his cyclotron and then quickly moved on. By 1939, the year he was awarded the Nobel for his achievements in developing that apparatus, Lawrence was planning the fourth and largest version–one with a 184-inch chamber and a magnet weighing thousands of tons. Its eventual successor, the Bevatron, began running in 1954. The name came from its ability to accelerate particles at energies up to billions of electron volts, a thousand times greater than those achieved by the first cyclotron. The discovery of the antiproton a year later, thanks to the high-energy collisions the Bevatron made possible, was its first dramatic success (and the reason for Uncle Emilio’s Nobel).
Yet Berkeley’s physics heyday would soon be over, just as the Cavendish’s had passed. Probing the structure of neutrons and protons would require beams of higher energy, and this meant even bigger and more expensive particle accelerators. Since it was becoming increasingly clear that no single institution could afford to construct or staff the new machines, consortiums had already begun forming to plan for building them. A group of universities in the eastern United States joined forces in 1947 to construct an accelerator on Long Island. The result was Brookhaven National Laboratory’s Cosmotron, which started running in 1952. Europe’s major nations made their own plans, loath to be left behind although World War II had left them impoverished. They banded together in 1954 to found CERN, the European Organization for Nuclear Research (the acronym comes from the French Conseil Européen pour la Recherche Nucléaire), in Geneva, Switzerland. Its first particle accelerator began operation in 1957.
Packing My Bags for Switzerland
These advances were very much on my mind as I decided where to use the two-year postdoctoral fellowship I had been awarded by the National Science Foundation after completing my PhD thesis in 1963. CERN seemed to be the natural choice. A stay there would allow me to see more of my parents and, in some way, to reconnect with the Europe I had left behind. I made the decision without hesitation, even though CERN, having yet to make any major discoveries, seemed to suffer from an inferiority complex vis-à-vis its rivals in the United States. Spirits were nevertheless high there, as I found on arrival. In addition, the laboratory’s director general, Victor Weisskopf, was an inspiring presence, familiar to me because he had been a professor at MIT. Weisskopf, who came to CERN in 1961, appeared to represent a melding of the great old European tradition and the new American can-do attitude.
Though only in his mid-50s, Weisskopf had worked with the likes of Bohr and Pauli during the heyday of quantum mechanics and the beginnings of nuclear physics. After arriving as an immigrant to the United States from Europe in his late 20s, he had been an active participant on the atom bomb project and had later helped develop MIT as a center for physics teaching and research. He now seemed to be the right person to guide CERN in its transition to world eminence. Weisskopf also tried to re-create, in a completely different and much larger setting, some of the atmosphere he had benefited from in Copenhagen 25 years earlier. Writing of Bohr in his autobiography, he says, “From the beginning he made the most profound impression on me. He was my intellectual father.” And Weisskopf tried to convey some of this same sense of family to the young CERN scientists–speaking informally about physics on Monday afternoons, inviting us to his Geneva house, and always emphasizing what a wonderful enterprise we were engaged in, how lucky we were to be able to work on the great and beautiful problems of physics.