Science: Electron Fattener

With a flashing of 84 rectifier tubes and a chugging of six great electromagnets, the world's biggest (300 million volt) betatron started operating last week at the University of Illinois. Betatrons look something like cyclotrons, but instead of spinning protons or heavier particles, they spin lightweight electrons.

In the Illinois betatron, the electrons circle a nine-foot, doughnut-shaped tube 140,000 times in four one-thousandths of a second, reach a speed only one-millionth part less than the speed of light. In accordance with Einstein's laws of relativity, the speed increases their mass 600 times. (The last few m.p.h. come hardest. Theoretically, if they reached the speed of light, their mass would be infinite—which is impossible.)

When the fattened-up electrons are making their last turn around the tube, they are deflected by special magnets and made to strike a tungsten target, knocking out of it a slender beam of enormously powerful X rays. In effect, a betatron is an outsized X-ray tube; the X. rays are its desirable product.

The rays of the Illinois betatron are too powerful to use in treating cancer or for photographing, say, the innards of battleships. Instead of merely passing through matter, they stir up showers of high-speed electrons which fog a photographic plate. The principal purpose of the Illinois betatron will be to produce copious supplies of mesons, the particles which are thought to be connected with the "binding force" that holds atomic nuclei together. Powerful X rays knock mesons out of the nuclei. Said Professor Donald William Kerst, developer of the betatron and builder of the Illinois machine: "We are in business, making mesons."

Kerst is also the betatron's christener. At first he thought of calling it the "Ausserordentlichhochges chwindigkeit-electronenentwickelndesschwerab eitsbei-gollitron," German for "extraordinarily high-speed electron generator, hard work by golly-tron." He settled for "Betatron," from beta particle (high-speed electron).