Vice-President, Nuelcar-Chicago Corporation, Des Plaines, Ill.
Van Zelst, TW
President, Soiltest, Inc., Chicago, Ill.
In 1932, Sir James Chadwick discovered that when alpha particles were allowed to fall upon a piece of beryllium in contact with a block of paraffin, protons could be detected at the surface of the paraffin block. They were not detectable when the paraffin was removed. Chadwick deduced that neutral particles were formed by the alpha reaction on beryllium which were able to eject protons from the paraffin block by collision. This particle he called the neutron. Thus the interaction and moderation of neutrons by hydrogen atoms was inherent in the discovery of the neutron itself.