LRL Accelerators

THE 184-INCH SYNCHROCYCLOTRON

LAWRENCE RADIATION LABORATORY

UNIVERSITY OF CALIFORNIA, BERKELEY, CALIFORNIA

Synchrocyclotron Building

Contents

•  Page
• THE 184-INCH SYNCHROCYCLOTRON 2
• PRINCIPLE OF OPERATION OF A CONVENTIONAL CYCLOTRON 3
• THE PRINCIPLE OF PHASE STABILITY 6
• DESIGN AND CONSTRUCTION OF THE 184-INCH SYNCHROCYCLOTRON 8

  Magnet 8
  Vacuum System 9
  Ion Source 10
  Radiofrequency System 10
  Internal Targets and Beam Extractor 12

• CYCLOTRON EXPERIMENTS 15

  Nuclear Physics 15
  Biophysics 18
  Nuclear Chemistry 19

• BIBLIOGRAPHY 20
• APPENDIX 21

THE 184-INCH SYNCHROCYCLOTRON

His success with the 60-inch cyclotron in 1939 led Dr. E. O. Lawrence to propose a much more powerful accelerator, one which could produce new types of nuclear rearrangements and even create particles. Grants totaling $1,225,000 permitted work to start on the 184-inch cyclotron in August 1940.[1] It was designed to accelerate atomic particles to an energy of 100 million electron volts (Mev), five times that possible with the 60-inch machine.

Fig. 1. The electromagnet under construction during the period 1940 to 1942.

Before the new cyclotron could be finished World War II began. Construction on the cyclotron was therefore halted. However, because of interest in separating the isotopes of uranium by the electromagnetic method, work on the giant magnet continued at an even faster pace. This magnet would contain 3700 tons of steel in its yoke and pole pieces, and 300 tons of copper in its exciting coils (Fig. 1). By May 1942 the magnet was completed. During that summer it was used in a pilot plant to separate the first significant amounts of U²³⁵ ever obtained. The 184-inch magnet remained in use in a research and development program at Berkeley until the end of the