The possibility of applying artificial radioactive elements to biologic research and radiation therapy has aroused much interest. Some investigators have prophesied that artificial radioactive elements may eventually replace radium and radon for certain types of therapy.
M. and Mme. Joliot, son-in-law and daughter of the late famous Mme. Curie, were awarded the Nobel Prize (1934) for their discovery of artificial radioactivity. They bombarded boron with alpha rays, making a substance called radionitrogen, which gave off radiation resembling the radiation from radium. The life of the product, which is about fourteen minutes, is insignificant compared to the life of radium. Other investigators in many parts of the world have followed this line of research. For the bombarding medium some have used the neutron, the electrically uncharged elementary particle possessing nearly the same mass as the hydrogen atom, and others have used the deuteron, the charged atom of heavy hydrogen. To date, more than forty elements have been made artificially radioactive, and the half-life of this radioactivity varies from a few seconds to about fourteen days.
In the radiation laboratory in the Department of Physics, University of California, a device called the cyclotron has been invented, which creates exceedingly high velocities of deuterons.1 The high velocity of these deuterons is generated between the poles of a huge electromagnet. Essentially, its operation consists of deuterons being continuously accelerated round and round in a spiral. This gives them their high speed energy, which otherwise would be unobtainable. The deuterons reach a wall of one electrode and pass out of it through a slit; then they pass through a thin