SLAC celebrates 50 years

SLAC has had a remarkable first 50 years, which were celebrated in a special event this past month. Although the theme of this event focused on the next 50 years, the achievements of the past inform the future plans and prospects. The physics achievements of SLAC were duly noted at the event by the American Physical Society, which designating SLAC as an APS Historic Site. As APS Past President I had the honour and distinct pleasure of presenting this award and I share below my address at the ceremony.

The APS Historic Sites Initiative was created in 2004 with the purpose of raising public awareness of physics through acknowledgement of important past scientific advances. The Society has established a distinguished Historic Sites selection committee that evaluates potential historic physics sites in the United States. The Historic Sites committee is represented today by Ben Bederson, chair of the committee, and the APS leadership by Mac Beasley, Vice President of the APS and myself. (Bob Byer, President, is in China for the 80th anniversary of their Physical Society).

Prior to SLAC, 26 sites have been selected  as APS Historic Sites, including those recognising the achievements of Benjamin Franklin, Joseph Henry, J.W. Gibbs, Michelson and Morley, Rutherford and Soddy, Arthur Compton, Robert Millikan, and Carl Anderson (from my institution), as well as for the invention of the transistor, and the BCS theory of superconductivity.

Recent awardees include Maiman and Hughes Research Laboratories (Malibu) for the first demonstration of the laser some 50 years ago, Charles Keeling and Scripps Institute of Oceanography for the experiments yielding the Keeling Curve that show the rise in the level of carbon dioxide in the atmosphere and to Brookhaven Laboratory for multiple achievements in physics, much like today’s award to SLAC.

As Past-President of the American Physical Society and because of my long associations with SLAC, I am especially pleased to be able to dedicate SLAC as an APS historic site.

This is a citation from the inscription on the plaque:

“In recognition of the SLAC National Accelerator Laboratory, formerly Stanford Linear Accelerator Center, established in 1962 and home of the 2-mile Stanford Linear Accelerator and the SPEAR electron storage ring. These two accelerators played instrumental roles in the discovery of quarks, the establishment of the Standard Model of particle physics, and the invention and use of high-brightness X-ray synchrotron and laser sources for the study of solid-state materials, surfaces, and biological structure.”

Wolfgang K. H. (Pief) Panofsky, SLAC’s first director, led the creation of the SLAC Laboratory around its centrepiece, the 2-mile linear accelerator that has led to so many discoveries in particle physics and beyond. This accelerator, motivated to a large extent by the earlier electron scattering experiments on the Stanford campus, represented a truly bold step to high energies. The initial experiments included measurements of electron and positron scattering like had been done at lower energies on campus (I participated in those experiments, then left the experiment, just before they went on to discover the spectacular scaling behaviour in what is called deep inelastic scattering.) That result was quickly interpreted as an evidence for a constituent quark-like structure in the proton for which Jerry Friedman, Henry Kendal and Dick Taylor were awarded the Nobel Prize.

Burt Richter led another bold step that has been typical of SLAC, that of initiating and building the SPEAR electron-positron colliding beam facility. We are still benefitting from the legacy of this machine that effectively represented the birth of collider physics, both in terms of a high-energy colliding beam facility, and in developing the first general-purpose 4π or full-coverage detector. This project provided the model for how to advance particle physics to much higher energy by working in the centre of mass system through colliding beams (instead of scattering off a stationary target). SPEAR has spawned several generations of accelerators around the world since that time. The physics achievements of SPEAR were truly astounding: the discovery of the J/Psi and charmed particles by Burt Richter and collaborators, as well as the discovery of our heaviest lepton, the Tau, by Marty Perl and collaborators. Both resulted in Nobel Prizes for the laboratory.

Two more generations of circular colliding beam facilities have been built and exploited at SLAC – PEP I and PEP II. PEP II, having asymmetrical beams, provided precision measurements of the CP violating parameters for B decay that established the theory put forward by Kobayashi and Maskawa and led to their Nobel Prize.

In the SLAC tradition, other important facilities have been developed, including especially the synchrotron X-ray radiation facility at SPEAR, where many of the techniques for high-brightness light sources were first developed, and again it yielded a rich physics programme that included the Nobel Prize work of Roger Kornberg understanding the process by which genetic information from DNA is copied to RNA. Of course, this general field of photon physics has now become the central theme of the laboratory in recent years with the development of LCLS.

This SLAC tradition of developing innovative new ambitious facilities to perform ground-breaking experiments has led to many other important discoveries in the history of the laboratory, but I would be remiss if I didn’t mention the SLAC Linear Collider, which provided the first precision measurements of the Z0, and demonstrated the concept of what is my own present activity, the development through a worldwide effort to develop a design for a future linear electron-positron collider to follow and complement the CERN LHC.

SLAC is an amazing institution. It is a place where great scientists have been able to do great science! The APS is proud to be able to honour SLAC as one of our historical sites and to do it at the time of this 50th anniversary celebration. We congratulate you!