Ernest Rutherford

Ernest Rutherford

Ernest Rutherford was born in New Zealand in 1871 as one of 12 children. It was Rutherford who first "split" an atom and who discovered the atomic "nucleus", a name that he invented. For this he is regarded as the greatest experimental physicist of his time.

Rutherford was one of the first and most important researchers in nuclear physics. Soon after the discovery of radioactivity in 1986 by the French physicist Antoine Henri Becquerel, Rutherford discovered the three different types of radiation. By covering his Uranium with thin foils of aluminum, gradually increasing the number of foils. For the first three layers of foil the radiation escaping from the uranium decreased progressively, suggesting an ordinary law of absorption. More thickness of aluminum, however, had little further effect in reducing the radiation at first, but eventually the intensity of the radiation began to diminish again as even more foils were added. These experiments showed that there were at least two distinct types of radiation- one that is very readily absorbed, which he called the alpha - radiation, and the other more penetrative character which he called the beta - radiation. He also had believed that he had found a third more penetrating radiation. The Frenchman, Paul Villard, officially gave this third radiation. He named it, after Rutherford's first two radiation discoveries, the gamma- radiation. It was these discoveries in radiation that opened the door to the rest of Rutherford' discoveries.

Using this alpha radiation, Rutherford started to experiment putting it through other materials to get the effects. It was in one of these experiments with gold that he was able to figure out what an atom looks like. He found that a countable number of alpha particles actually bounced back from a thin sheet of gold foil. Of course the majority of the particles went straight through the gold and were only slightly scattered. Rutherford said that this was the most surprising result he had known. He said that this discovery of the alpha particles actually bouncing off the gold was as surprising to him as firing a fifteen inch shell at a piece of tissue paper and having it bounce back and hit you. From this statement we can see how immersed Rutherford actually was in his studies. By this experiment it seemed clear to Rutherford that the alpha particle occasionally encountered such an intense field in the atom that it was turned back in its path as the result of a collision.