California Institute of Technology. Synchrotron Laboratory.

The synchrotron was a new type of electron accelerator, succeeding the cyclotron by extending its voltage range. The Caltech Synchrotron, at one-billion volts (1 BeV), was the most powerful machine of its type ever built. Professor Robert L. Walker was in charge of the design, construction and eventual operation. In preliminary use in 1950; modified to increase energy level to 1.5 BeV by 1961. Operation ended in February 1970.

Introduction

In the Spring of 1949, the Institute announced plans to build a one-billion volt ("1 BeV") electron accelerator. Robert Bacher, chairman of Caltech's Physics Division, stated: "The purpose of the new accelerator will be to seek additional knowledge about the nature of the forces that hold atomic nuclei together." The new accelerator, the synchrotron, would be the most powerful machine of its type ever built. The funding of the project by the U.S. Atomic Energy Commission marked the beginning of high energy physics at Caltech.

The synchrotron was the successor to the cyclotron--developed in 1932 by E.O. Lawrence--in that it extended the voltage range of high energy accelerators by the application of new physical principles. These were developed independently in 1945 by Edwin M. McMillan at Berkeley (Caltech B.A. 1928, M.S. 1929, Ph.D. 1932) and V. Veksler in Russia. McMillan later won the Nobel Prize in Chemistry in 1951 and the Atoms for Peace Prize jointly with Veksler in 1963.

The Caltech machine went into preliminary use in the summer of 1950. By 1956 it had been modified to increase its energy level to above 1 BeV. In 1961, it reached 1.5 BeV, accelerating electrons to within a few feet per second of the speed of light. Important early experiments were conducted on K-meson photoproduction, and investigations of the electromagnetic couplings of a growing number of pion-nucleon resonances were carried out. Over the years, the program concentrated largely on studies of photoproduction processes in the available energy region.

Operation of the synchrotron ended in February, 1970. Well before this time, it had become evident that collaborative efforts in experimental work were more efficient because of the complexity of the work involved and the cost of the equipment. A user program, initiated in 1962, linked Caltech with Berkeley's Lawrence Radiation Laboratory, Brookhaven National Laboratory, the Stanford Linear Accelerator, and other universities. The user program continued to expand, as accelerators entered a "super" category in both size and cost.