SPEED OF HELIUM.

Hawera Star, Volume XLVI, 4 May 1927, Page 5

SPEED OF HELIUM.

10,000 MILES PER SECOND

“Don’t break that tube,’’ said Sir Ernest Rutherford to his assistant, when speaking at the Royal Institution recently. “If you do,” this room will not be able to be used for radioactive experiments for a long period—perhaps 40 years.” The lecturer’s subject was “The Alpha Rays and Their Application to Atomic Structure.” Of the various iypes of radiation emitted during the transformation of radium and other radio-active bodies, the alpha rays, he said, are the most important. They consist of a stream of positively charged particles of helium, which are spontaneously ejected with a speed of about 10,COO miles a second. milligram of radium about 10,00(7,000 of these particles are expelled eapli second. When these particles come to rest they become atoms of the rare gas helium, and it seems probable that the neater part of the helium found in Hie earth is due to alpha particles of radio-active bodies which have lost their charge. The alpha particles have the greatest energy of motion of any particles known to science When they are absorbed by matter, heat is evolved corresponding to their kinetic energy, and the constant and rapid evolution of heat from radium is due to this bombardment of matter by alpha particles The study of the alpha particles had thrown much light on the structure of the atom. The deflection of the alpha particles as the result of a close collision with an atom of matter hrst wave us definite information on the nuclear structure of the atom, and had allowed us to determine the magnitude of the charge on their minute nucleiis for different elements. The bombardment of elements by the swiftest alpha particles showed in a definite way that the nuclei of the number of atoms could l>e broken up in an intense collision with an alpha particle. By special amplifiers the small currents due to the ionisation of the alpha particle were magnified about a million times and shown bv a galvanometer.