Matter to Matter

From a fortnight's press flurry of hazy ideas and inaccurate terms concerning something that had happened to the atom at Cambridge, England, this much could be clarified last week:

Dr. J. D. Cockroft, 34, and Dr. E. T. S. Walton, who is still in his 20's, workers under Ernest Lord Rutherford at the Cavendish Laboratories, were firing protons down a long vacuum tube at a target of lithium, a metal belonging to the sodium-potassium family of elements. A proton is a particle of positive electricity. Drs. Cockroft & Walton were aiming at the rapidly moving atoms in the piece of lithium. The protons traveled nearly 4,000 mi. per sec. with forces varying from 120,000 to 600,000 volts.

One proton in ten million struck a lithium atom and adhered to it. Then something logical, but nonetheless remarkable, happened. The lithium atom has a nucleus which contains seven protons and four electrons which bind the protons together. Around the nucleus pulsate three more orbital electrons. When a proton adhered to a lithium nucleus for Drs. Cockroft and Walton, there were eight protons in the nucleus. The overloaded nucleus split in half. Each half contained four protons and two electrons. Such a packet of energy is the alpha particle which radium emits. It is also the nucleus of the helium atom.

Other investigators, including Lord Rutherford, have apparently made one element out of another--carbon from nitrogen, gold from mercury--by chipping particles from heavy elements and reducing them to lighter elements. Drs. Cockroft & Walton are the first apparently to obtain one element from another by adding to the nucleus of the second.

Dr. Robert Andrews Millikan of California Institute of Technology predicates his entire theory of cosmic ray origin on the mathematics of element creation. A hydrogen atom consists of one proton and one electron. The atom has a certain weight. A helium atom contains four protons and two electrons (an alpha particle) in its nucleus, and two more electrons in its shell. A helium atom thus has four times as many protons and four times as many electrons as has a hydrogen atom. But a helium atom weighs slightly less than four hydrogen atoms. The difference escapes as cosmic rays when four hydrogens assemble to form a helium, reasons Dr. Millikan.

Similarly the brace of helium nuclei which Drs. Cockroft & Walton obtained by plugging one proton into one lithium nucleus weighed less than the source material. The loss of mass is represented by a gain in energy which drives the two helium nuclei of the Cambridge experiments at 8,000,000 volts of energy each, a tremendous gain from the 120,000 to 600,000 volts which the men initially put into their vacuum tube. But this energy is released only once in ten million times by the shooting protons. As a source of energy the experiment is thus only between 0.00026% and 0.00133% efficient. Nevertheless, the feat of having added matter to matter remains historic.

This file is automatically generated by a robot program, so reader's discretion is required.