| 单词 | alpha ray |
| 例句 | The result of their bombardments of boron and other light elements by alpha rays, moreover, had led them to propose that the proton was composed of a neutron and a positive electron, or positron. Big Science 2015-07-07T00:00:00Z After a few minutes of viewing, the discoverer of alpha rays crawled from the hutch and declared, “I know an alpha when I see one.” Big Science 2015-07-07T00:00:00Z In 1935 the dominant lab in this category had been the Cavendish, which specialized in reactions induced by alpha rays and protons; Berkeley could only compete in research on deuterons. Big Science 2015-07-07T00:00:00Z Eventually alpha rays were identified as helium atoms stripped of their electrons—that is, helium nuclei-—and beta rays as energetic electrons. Big Science 2015-07-07T00:00:00Z Their method involved bombarding aluminum foils with alpha rays produced by their usual rudimentary source, a hunk of the inexpensive but vigorous alpha emitter polonium. Big Science 2015-07-07T00:00:00Z “Keeps out the alpha rays, Max! You don’t get old.” Annie Hall at 40: ranking the film's funniest moments 2017-04-20T04:00:00Z He had named them alpha rays, but as he found he could not get them to penetrate even a thin sheet of paper, he was confident that they must be atoms of matter. Autobiography of an Electron Wherein the Scientific Ideas of the Present Time Are Explained in an Interesting and Novel Fashion 2011-06-19T02:00:25.633Z This is due to the bombardment of the zinc sulphide by a type of ray called the alpha ray. A Brief Account of Radio-activity Some of these particles, the alpha rays, are atoms of another element, helium, charged with positive electricity and are ejected with a velocity of 18,000 miles a second. Creative Chemistry Descriptive of Recent Achievements in the Chemical Industries In the process of transformation giving rise to these several derived substances, atoms of helium—the alpha rays—projected with great velocity into the surrounding mineral, occasion the colour changes referred to. The Birth-Time of the World and Other Scientific Essays The first-named constitutes the beta, and the second the alpha rays. The New Physics and Its Evolution Now, the alpha rays are the shortest," he launched forth, "in length let us say one inch. The War Terror Beta Rays The beta rays are negatively charged and have a greater penetrating power than the alpha rays. A Brief Account of Radio-activity Time of half Radio- Properties decay activity Radium About 2600 years alpha rays Element chemically analogous to barium. Darwin and Modern Science Bragg and Kleeman and others have investigated the career of the alpha ray when its path or range lies in a gas at ordinary or obtainable conditions of pressure and temperature. The Birth-Time of the World and Other Scientific Essays The alpha rays are positively charged, and are projected at a speed which may attain the tenth of that of light; M.H. The New Physics and Its Evolution "Then it is the alpha rays with which we are concerned mostly now?" The War Terror They show a strong deflection in magnetic and electric fields, have less ionizing power than the alpha rays, and a velocity of the same order as light. A Brief Account of Radio-activity But in point of fact the ionisation due to an alpha ray is sui generis. The Birth-Time of the World and Other Scientific Essays Let us calculate the number of alpha rays which may have gone to form a halo in the Devonian granite of Leinster. The Birth-Time of the World and Other Scientific Essays They have about a hundred times less ionizing power than the alpha rays. The New Physics and Its Evolution We must conclude that the effect of the ionisation due to the alpha ray has not been to alter fundamentally the conditions which give rise to the optical properties of the medium. The Birth-Time of the World and Other Scientific Essays The alpha rays are projected particles which lose energy in penetrating matter. A Brief Account of Radio-activity The colouration is not due to an accumulation of helium atoms, _i.e._ of spent alpha rays. The Birth-Time of the World and Other Scientific Essays A single alpha ray fired from radium C will produce 2.37 x 105 ions in air. The Birth-Time of the World and Other Scientific Essays On the other hand, their ionizing power is 10,000 times less than that of the alpha rays. The New Physics and Its Evolution If geological time since the Devonian is 400 millions of years, then 1,200 millions of alpha rays are concerned in its genesis. The Birth-Time of the World and Other Scientific Essays Identification of the Rays The alpha rays have been identified as similar to the so-called canal rays. A Brief Account of Radio-activity For it proves that in the mineral the alpha ray gives rise to the same increased ionisation towards the end of its range, as Bragg determined in the case of gases. The Birth-Time of the World and Other Scientific Essays Before leaving our review of the general laws governing the passage of alpha rays through matter, another point of interest must be referred to. The Birth-Time of the World and Other Scientific Essays Phosphorescence and fluorescence seem especially to result from the alpha and beta rays, particularly from the alpha rays, to which belongs the most important part of the total energy of the radiation. The New Physics and Its Evolution It is remarkable that uranium at the present time is apparently responsible for two alpha rays of very different ranges. The Birth-Time of the World and Other Scientific Essays Alpha Rays Consist of Solid Particles In the first place, these alpha rays have been found to be made up of solid particles, that is, of what we are accustomed to call matter. A Brief Account of Radio-activity The explanation does not suggest that the ionising power of any one ray is actually diminished before it finally ceases to be an alpha ray. The Birth-Time of the World and Other Scientific Essays The nature of the change produced by the alpha rays is unknown. The Birth-Time of the World and Other Scientific Essays Polonium contains especially alpha rays and a few gamma rays. The New Physics and Its Evolution Each alpha ray leaving the nucleus will just attain its range and then cease to affect the mica. The Birth-Time of the World and Other Scientific Essays The alpha ray carries a positive charge of double the ionic amount. The Birth-Time of the World and Other Scientific Essays When the alpha ray has sufficiently slowed down, its power of passing right through atoms, without appreciably experiencing any effects from them, diminishes. The Birth-Time of the World and Other Scientific Essays I think there is only the one conclusion open to us; that some other source of alpha rays, or a faster rate of supply, existed in the past. The Birth-Time of the World and Other Scientific Essays Such is a brief summary of the climax of radioactive discovery:—the birth, life and death of the alpha ray. The Birth-Time of the World and Other Scientific Essays Now Geiger has investigated and proved the existence of scattering of the alpha ray by solids. The Birth-Time of the World and Other Scientific Essays Rutherford, Sir E., determination of age of minerals, 19, 20; age of rocks by haloes, 22; derivation of actinium, 226; artificial halo, 229; number of alpha rays from one gram of radium, 237. The Birth-Time of the World and Other Scientific Essays How the work of the alpha ray is sometimes recorded visibly in the rocks and what we may learn from that record, I propose now to bring before you. The Birth-Time of the World and Other Scientific Essays The fundamental criterion of radioactive change is the expulsion of the alpha ray. The Birth-Time of the World and Other Scientific Essays The proof is complete that we are dealing with the effects of alpha rays. The Birth-Time of the World and Other Scientific Essays When an alpha ray is discharged from the transforming element into a gaseous medium its velocity is rapidly checked and its energy absorbed. The Birth-Time of the World and Other Scientific Essays When its initial velocity is expended the helium atom gives up its properties as an alpha ray and thenceforth remains possessed of the ordinary varying velocity of thermal agitation. The Birth-Time of the World and Other Scientific Essays We see here a peculiarity of the ionisation effected by alpha rays. The Birth-Time of the World and Other Scientific Essays It means that, knowing the chemical composition and density of any medium whatsoever, solid, liquid or gaseous, we can calculate accurately the distance to which any particular alpha ray will penetrate. The Birth-Time of the World and Other Scientific Essays The loss of mass between radium and uranium-derived lead can be accurately estimated by the number of alpha rays given off. The Birth-Time of the World and Other Scientific Essays |
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