What is an Atom Smasher?
Both atoms and window panes will be smashed when they are struck forcibly by a suitable object. Though for centuries mischievous boys have known the secret of smashing a window pane by means of pebbles flung by a sling, it was only within recent years that scientists learned how to smash the atom, a feat which was for a long time considered impossible.
An important clue to the solution of the mystery of atom smashing was obtained late in the last century, when it was found that atoms of elements such as thorium and radium were self-splitting, like a fire-cracker that blows itself into bits. Scientists studied these radioactive elements, as they were named, for here was the first evidence that one element could be changed into another.
In 1919 Lord Rutherford bombarded nitrogen gas with the alpha particles which are shot out by radioactive elements as they undergo certain of their changes. Some of the nitrogen was changed into oxygen. For the first time in history, man had succeeded in changing one element into a different one. In this way did modern science realize the dream of the ancient alchemists who strove in vain to change common metals like copper and lead into precious ones like gold and silver.
Today atoms are being changed by means of huge atom-smashing machines of which several types exist. Perhaps the best known and most widely used of these machines is the cyclotron, an atom smasher invented by Ernest Orlando Lawrence of the University of California. Just as a youngster twirls a sling overhead and lets the pebble in it fly at a tin can on a fence, so does the cyclotron whirl atomic projectiles round and round until they have acquired great velocity, then hurls these electric pebbles at a chosen target.
Like a store of pebbles which a boy may carry in his pocket for use in a sling, the cyclotron in a roundabout way gets its atom- smashing bullets from a gas at low pressure contained in a tank. If the gas is hydrogen, the cyclotron hurls protons; if helium is in the tank, alpha particles are fired; and if the gas is heavy hydrogen, deuterons are shot at the target.
Besides the cyclotron, another type of atom smasher favored by scientists is the Van de Graaff electrostatic generator, by means of which small electric charges are collected from endless belts. These charges are stored until high voltages are created to send atomic bullets against atomic targets.
Neutrons are produced in relative abundance from the nuclei of atoms bombarded by deuterons or alpha particles. These neutrons are in turn directed at other objects, such as atoms or cancer cells. The neutron makes a good atomic bullet because, though it has the mass of a proton, it lacks an electrical charge and hence it is not repelled by the electrical forces around an atom’s nucleus.
Atom-smashing devices have changed most of the elements into other elements, and have made many elements artificially radioactive. The cyclotron has changed common table salt into a radioactive salt which has an activity equivalent to the radium emanations from four million dollars worth of radium.
Such radioactive salts have been used in the treatment of cancer patients. Since the radioactivity dwindles quickly, the salts may be taken by mouth or may be injected. Actual radium used in this manner would be dangerous, as the activity of radium continues for so long that the healing effects would be overcome by the destructive effects on healthy tissue.
By means of the cyclotron gold has been created from platinum. This is certainly not a practical method for obtaining gold, since the platinum used as the raw material is more expensive than the gold. We should not consider the transmutation of a more valuable element into one less valuable as a foolish or wasteful experiment, however. As Dr. Lawrence remarked, “The information we are getting is more valuable than gold.”
Bismuth, an ordinary element, has been changed into a long-lived form of radium by the cyclotron. Neutrons are being used instead of X-rays and radium to kill cancer growths, though it is still too new a treatment for scientists to be sure of its worth. Many atoms hit by neutrons have been split with a tremendous release of atomic energy. If such explosions could be created efficiently on a large scale, we should have at our command a new source of energy greater than any now used.
