Kenneth MacKenzie, 90; Helped Discover Astatine, Built UCLA’s Atom Smasher


Kenneth Ross MacKenzie, who worked on the atomic bomb as a graduate student, helped discover the element astatine, helped build UCLA’s cyclotron and later concentrated on studying thermonuclear fusion as a nonpolluting energy source, has died. He was 90.

MacKenzie, who taught physics at UCLA for more than four decades beginning in 1947, died July 3 at his home in Los Angeles of complications after a stroke.

As a doctoral candidate at UC Berkeley under atomic scientist Ernest O. Lawrence, MacKenzie was one of the men who discovered element 85 of the periodic table: astatine.

The radioactive substance, formed by bombarding an isotope of bismuth with alpha particles, helped verify the accuracy of the table.


MacKenzie also helped his mentor built the first cyclotron at what is now the Lawrence Radiation Laboratory.

As World War II neared, MacKenzie was assigned to help solve the problem of large-scale separation of uranium-235 at the federal Oak Ridge, Tenn., laboratory, a crucial step in the Manhattan Project to create the atom bomb.

Adapting needs to wartime shortages, MacKenzie and his colleagues borrowed 14,700 tons of silver from the U.S. Treasury and melted it into strands to replace copper in their magnetic coils. After the war, the silver was melted into bullion and returned to the treasury.

MacKenzie joined the UCLA faculty in 1947 and helped install Lawrence’s original cyclotron, the first atom smasher of its kind in the world, which was shipped from Berkeley to Westwood. In 1955, he directed construction of a 49-inch cyclotron for UCLA and formally retired the Lawrence device.


By 1958, MacKenzie and his colleague Byron Wright had developed such expertise in building cyclotrons that they formed MEVA Corp. to built cyclotrons for teaching physics. They also constructed a seven-ton model magnet and power supply for the Naval Radiological Defense Lab in San Francisco. Their firm was later bought by Hughes Aircraft Co.

When MacKenzie turned to studying plasma gases for use in fusion energy, he founded UCLA’s Plasma Physics Laboratory. He focused his research and teaching on fusion technology and studying dark matter. As an emeritus professor, he continued his research long after leaving the classroom.

A native of Portland, Ore., MacKenzie grew up in Victoria, Canada, and earned his undergraduate degrees at the University of British Columbia.

MacKenzie is survived by his second wife, Verna; three children from his first marriage, Robert of Redondo Beach, Wallace of Riverside and Maryann M. Johnson of Blue, Ariz.; three stepsons, Mark, Thomas and Bryce Augustine; a sister, Betty Nickull; two brothers, Robert and Ronald; and one half-brother, Rod MacKenzie.


A public memorial service will be scheduled at UCLA.