GAMMA RAYS

Otago Daily Times, Issue 21542, 14 January 1932, Page 9

GAMMA RAYS

LORD RUTHERFORD’S NEW . THEORY ; DISCOVERY OF PAST FEW WEEKS; (From Our Own Correspondent.) LONDON”, December 3. r . Lord Rutherford and his helpers haver been making what he called a concentrated attack on the origin of the. Gamm<y Rays, and a new theory has been eluci-' dated. Lord Rutherford was opening the annual congress of the British Institute of Radiology when he made this announcement. The discovery of the X-rays by Rontgen in 1895, he said, marked a veritable epoch in the history of science, not only because of the discovery itself, but because it brought in its train two other great discoveries—that of radioactivity by Becquerel in 1896, which opened up a new science and had had an enormous influence on the development of our ideas on the structure of matter, and the discovery of the electron in the following year by Sir J. J. Thomson. The discovery of X-raya was a dividing line between what might be called the older and newer physics. It provided us with a weapon of great flexibility and power for throwing light on the internal structure of matter, -and its utility was as yet by no means exLord Rutherford proceeded to speak of the difficult problem of the origin of the, gamma rays from radium and the other, radio-active bodies. For a long time it had been known that the gamma rays were a very penetrative type of X-rays, but the question of how they were pro-, duced was very difficult to answer. Ik was at first natural to suppose that, us, the gamma rays appeared to come from, bodies that produced the swift beta rays, or electrons, thev were connected with a sudden escape of the electrons expelled from a nucleus. In recent years, however, opinion had hardened that thft; gamma rays must be due to the motions of heavier particles, like the protons or alpha particles, making up the nucleus. In the last year—and, he might say, in the last few weeks—there had been a con-, centrated attack on this question in the speaker’s laboratory at Cambridge; and he was now sure that the gamma rays arose from the alpha rays and had nothing whatever to do with the electrons from the nucleus. . ... The idea they now envisaged was that this minute nucleus probably consisted mainly of alpha particles—that was, of*’ helium nuclei. There was every reason; to believe that_ normally these alpha par-> tides were all in the same quantum state, but that when a beta particle was shot out from the atom it had a remarkably power of disturbing the alpha particles; 1 While some of the alpha particles mights be shot up to a higher level or energy and* might rest there for an infinitesimal; time, they fell back, and in falling back gave out their energy in the form of a gamma ray. It looked to him as if virtually all the gamma rays which they oh-, served—at any rate, all . those of higher; frequency—were derived from the motions' of alpha in the nucleus. Then recognition of this, he thought, would; throw light on the structure of the nucleus itself. 1 ' COST OF PHOTONS. Sir James Jeans, in an address to the institute, endeavoured to answer the tion, “What is Radiation? ” , He said: “Radiation is made of bullets' ' of electrical energy, hurtling through." empty space. They are spinning round aa ; if fired from a rifle, but are also capable*' of wave-like motions.” These bullet-like particles Sir James termed “ photons.” “ When we pay our electric light bills,”.' he said, “we are in effect buying photons;.■ The electric light company may tell us we are paying 6d a unit for our energy. What' they really mean is that we are paying £17,000,000 an ounce for our photons. “Yet, the sun is distributing photons* free of charge throughout space at the rate of over 4,000,000 tons a second. This,.,gives us some idea of the amazing pro- - digality and generosity of Nature as com-; pred with similar qualities in the electric light companies!—(Laughter.) “If we could learn the secret of anni-" hilating matter,” Sir James added, “we ' could turn an ounce of base matter of*.* any kind into an ounce of photons, and;.; we should have energy of which the pres-. s ent value is about £17,000,000. >•, “Doubtless prices will be lower then!