17 October 1990
The Royal Swedish Academy of Sciences has decided to award the 1990 Nobel Prize in Physics jointly to Professors
Jerome I. Friedman and Henry W. Kendall both of the Massachusetts Institute of Technology, Cambridge, MA, USA, and Richard E. Taylor of Stanford University, Stanford, CA, USA, for their pioneering investigations concerning deep inelastic scattering of electrons on protons and bound neutrons, which have been of essential importance for the development of the quark model in particle physics.
Professors Jerome I. Friedman and Henry W. Kendall, both of the Massachusetts Institute of Technology (MIT), and Richard E. Taylor, of the Stanford Linear Accelerator Center (SLAC), share this year's Nobel Prize in Physics. The value of the prize is 4 million Swedish crowns. The three prizewinners were key persons in a research team which in a series of investigations found clear signs that there exists an inner structure in the protons and neutrons of the atomic nucleus. What has become known as the "SLAC-MIT experiment" paved the way for further investigations of the innermost structures of matter. Ever since the beginning of this century, researchers have studied the inner structure of atoms. Our knowledge has increased successively, among other ways through the discovery (around 1910-1930) of the nucleus of the atom and its nucleons. During the 1950s there arrived on the scene a large number of what were termed hadrons, whose properties resembled those of nucleons. To reduce these to order, the concept of quarks was introduced, at the beginning of the 1960s. Yet it was impossible to see any traces of quarks in nature until the SLAG-MIT experiment itself.
The discovery was made when protons and neutrons were illuminated with beams from a giant "electron microscope" - a two-mile-long accelerator at SLAC in California, USA. The inner structure was interpreted to mean that quarks form the fundamental building blocks of protons and neutrons. The electrically neutral "glue" binding the quarks together is called gluons. All matter on earth, including our human bodies, consists to more than 99% of quarks with associated gluons. The little that remains is electrons.
Background information
The prizewinners' contributions
The work now rewarded was carried out at the end of the 1960s and the beginning of the 1970s by a group of researchers from MIT and SLAC. The work was a continuation of earlier investigations in which, using the electron as a probe, the structure of nucleons (protons and neutrons) was studied. Unlike in earlier investigations, electron beams of record-high energies were now available. These beams were supplied by a two-mile-long linear accelerator at SLAC, which afforded a "microscope" of higher resolution than earlier. No new phenomenon was expected: the experiment was fairly generally regarded as routine. Electron scattering against nucleons, but at lower electron energies, had been performed over two decades, and it was thought that enou
