| 单词 | alpha particle |
| 例句 | The 184-inch synchrocyclotron was one of the few machines that could accelerate alpha particles to the energies required to produce them. Big Science 2015-07-07T00:00:00Z The journal carried a report by Merle Tuve claiming that his Tesla coil could drive alpha particles to energies as high as 10 million electron volts without “any serious difficulty.” Big Science 2015-07-07T00:00:00Z The deflections occurred only when the alpha particle happened to strike this kernel directly or come close enough to be deflected by its electric charge. Big Science 2015-07-07T00:00:00Z In other words, alpha particles produced naturally by radium and polonium had exhausted their usefulness as probes of the nucleus. Big Science 2015-07-07T00:00:00Z On April 16 Cockcroft and Walton nervously summoned Rutherford to the basement so he might see for himself a scintillation pattern they thought heavily suggestive of alpha particles. Big Science 2015-07-07T00:00:00Z The Joliots had hypothesized that the same radioactivity they had induced in boron with alpha particles would be produced by deuterons acting on carbon. Big Science 2015-07-07T00:00:00Z Rutherford experimented by bombarding gold foils with alpha particles emanating from a glass vial of purified radium. Big Science 2015-07-07T00:00:00Z The yield was two alpha particles, each with two protons and two neutrons. Big Science 2015-07-07T00:00:00Z Radium emitted alpha particles at a meager 7.6 million electron volts and beta rays—that is, electrons—at only 3 million volts. Big Science 2015-07-07T00:00:00Z Every element bombarded with deutons yielded copious alpha particles, signifying their disintegration. Big Science 2015-07-07T00:00:00Z The experiment showed that most of the alpha particles passed through the foil with very slight deflection or none at all. Big Science 2015-07-07T00:00:00Z With two Manchester graduate assistants, Hans Geiger and Ernest Marsden, he set about finding one, using alpha particles as his tools. Big Science 2015-07-07T00:00:00Z When he accelerated an alpha particle through the chamber to seed his make-believe clouds, it left a visible trail–like the contrails of a passing airliner. A Short History of Nearly Everything 2003-05-06T00:00:00Z Working with James Chadwick, whose experimental skills matched his own, Rutherford trained his alpha particles on a series of gaseous targets: oxygen, carbon dioxide, even ordinary air. Big Science 2015-07-07T00:00:00Z They had bombarded dozens of elements with deuterons and assiduously tracked emissions of alpha particles during the bombardments; but the continued emission of electrons or positrons after the bombardments ended had escaped their notice. Big Science 2015-07-07T00:00:00Z She'd already begun to establish her reputation as a physicist, working on alpha particle scattering. She Cracked the Mystery of How to Split the Atom, But Someone Else Got the Nobel Prize for the Discovery 2023-09-07T04:00:00Z In one of the classic nuclear physics experiments at the beginning of the 20th century, an alpha particle was accelerated toward a gold nucleus, and its path was substantially deflected by the Coulomb interaction. College Physics for AP Courses 2015-08-12T00:00:00Z The most common are protons, neutrons, alpha particles, beta particles, positrons, and gamma rays, as shown in Figure 21.4. Chemistry 2019-02-14T00:00:00Z When a positively charged alpha particle strikes a nucleus, it reverses direction, much as a cue ball reverses direction when it strikes another billiard ball. Astronomy 2016-10-13T00:00:00Z Alpha decay is when an alpha particle, which consists of two protons and two neutrons, is emitted from the nucleus of an atom. An Introduction to Geology 2017-01-01T00:00:00Z Well before the pandemic, there were alpha particles and gamma rays. With coronavirus variants, world gets crash course on the Greek alphabet 2021-12-14T05:00:00Z Figure 30.10 Rutherford’s experiment gave direct evidence for the size and mass of the nucleus by scattering alpha particles from a thin gold foil. College Physics for AP Courses 2015-08-12T00:00:00Z Each alpha particle becomes an atom of helium gas. Chemistry 2019-02-14T00:00:00Z This process is called the triple-alpha process, so named because physicists call the nucleus of the helium atom an alpha particle. Astronomy 2016-10-13T00:00:00Z Fission Track: Fission track dating relies on damage to the crystal lattice produced when unstable 238U decays to the daughter product 234Th and releases an alpha particle. An Introduction to Geology 2017-01-01T00:00:00Z Clearly, the alpha particle crosses a kind of energetic barrier that normally prohibited passage, but how? When Physicists Follow their Guts 2021-08-18T04:00:00Z This is particularly indicated by the alpha particles that scatter to very large angles, much like a soccer ball bouncing off a goalie’s head. College Physics for AP Courses 2015-08-12T00:00:00Z A very thin barrier, such as a sheet or two of paper, or the top layer of skin cells, usually stops alpha particles. Chemistry 2019-02-14T00:00:00Z About 1 in 8000 of the alpha particles, however, completely reversed direction and bounced backward from the foil. Astronomy 2016-10-13T00:00:00Z Inside “Cloud Chamber,” otherwise invisible particles — protons, electrons, muons and alpha particles — manifest before the naked eye, swirling and sparkling when immersed in the tank’s frozen mist. Science + social justice + magic. The spellbinding formula of artist Glenn Kaino 2020-11-09T05:00:00Z An alpha particle is a nucleus of helium, a noble gas. Halogen nightmares 2020-09-01T04:00:00Z Since the gold nucleus is several times more massive than the alpha particle, a head-on collision would scatter the alpha particle straight back toward the source. College Physics for AP Courses 2015-08-12T00:00:00Z Types of radiation differ in their ability to penetrate material and damage tissue, with alpha particles the least penetrating but potentially most damaging and gamma rays the most penetrating. Chemistry 2019-02-14T00:00:00Z Superheavy atoms decay by emitting a series of alpha particles—bundles of two protons and two neutrons. A storied Russian lab is trying to push the periodic table past its limits—and uncover exotic new elements 2019-01-30T05:00:00Z But unlike cosmic radiation or radon gas, plutonium can lodge itself inside the body and deliver tissue damaging alpha particles over a lifetime. Blowing in the wind: Plutonium at former nuclear weapons site 2018-04-16T04:00:00Z According to the Nuclear Regulatory Commission, plutonium primarily emits alpha particles, which have a very short range. Work stops at Hanford after radiation found to have spread 2017-12-22T05:00:00Z Most alpha particles crash through but are relatively unaffected because of their high energy and the electron’s small mass. College Physics for AP Courses 2015-08-12T00:00:00Z It shoots off alpha particles that travel only a few inches and cannot penetrate the skin. Decades Later, Sickness Among Airmen After a Hydrogen Bomb Accident 2016-06-19T04:00:00Z Each alpha particle in the chain flies off with a characteristic energy. A storied Russian lab is trying to push the periodic table past its limits—and uncover exotic new elements 2019-01-30T05:00:00Z Three forms of radiation are emitted by radioactive substances: alpha particles, which are made of nuclei of helium atoms, beta radiation, which consists of electrons and gamma radiation, a form of high-energy electromagnetic radiation. How UK scientists solved Alexander Litvinenko riddle 2016-01-16T05:00:00Z Those slabs, he said, are at least 6 feet underground and painted over to prevent the escape of radioactive alpha particles. Rocky Flats stirs strong emotions 10 years after cleanup 2015-10-17T04:00:00Z A thin gold foil was placed in the beam, and the scattering of the alpha particles was observed by the glow they caused when they struck a phosphor screen. College Physics for AP Courses 2015-08-12T00:00:00Z William Jackson, a young Air Force lieutenant, helped with some of the first testing near the craters, using a hand-held alpha particle counter that could measure up to two million alpha particles per minute. Decades Later, Sickness Among Airmen After a Hydrogen Bomb Accident 2016-06-19T04:00:00Z Only later—when the scientists comb through the raw data and match every detected alpha particle to a specific element in the decay chain—can they reconstruct which element they initially created. A storied Russian lab is trying to push the periodic table past its limits—and uncover exotic new elements 2019-01-30T05:00:00Z It produces a lot of energy but in a confined space because alpha particles are easily blocked, for example by paper or skin. Litvinenko: A deadly trail of polonium - BBC News 2015-07-28T04:00:00Z The husband-wife team of Joliot-Curies and other physicists from Germany had observed a penetrating radiation arising from beryllium when it was bombarded by alpha particles. Ernest Rutherford, master of simplicity 2013-08-30T21:45:02.847Z The incident massive alpha particles would suffer only small deflections in such a model. College Physics for AP Courses 2015-08-12T00:00:00Z In the first decay, element 115 turned into element 113 while emitting a chunk known as an alpha particle. Made in Lab, Fleeting Element May Join Periodic Table 2013-08-28T00:34:51Z The new drug contains radium 223, which targets bone and emits alpha particles that are far more massive and energetic than the beta particles emitted by older radioimmunotherapies like strontium. Well: New Radiation Therapy Prolongs Prostate Cancer Survival 2013-07-17T21:25:13Z Hoyle state nuclei almost always decay right back into beryllium and an alpha particle. The Hoyle State: A Primordial Nucleus Behind the Elements of Life 2012-12-06T15:15:00.267Z Whether he was bouncing alpha particles off nuclei, studying the disintegration of atoms or discovering radioactive transmutation, Rutherford’s main goal was to illustrate deep physical principles in the simplest and most direct way possible. Ernest Rutherford, master of simplicity 2013-08-30T21:45:02.847Z Instead, Rutherford and his collaborators found that alpha particles occasionally were scattered to large angles, some even back in the direction from which they came! College Physics for AP Courses 2015-08-12T00:00:00Z In order to become more stable, the nucleus of an actinide element undergoes radioactive decay, releasing gamma rays, alpha particles, beta particles, or neutrons. The Disappearing Actinides, and Other Frustrations from the Bottom Row of the Periodic Table of the Elements 2012-01-27T18:45:02.817Z "It takes only a single alpha particle to kill a cell," Parker said. Bayer drug a "major new player" in prostate cancer 2011-09-23T22:12:32Z Like a bent arm, the Hoyle state takes the shape of an obtuse triangle with an alpha particle at each vertex. The Hoyle State: A Primordial Nucleus Behind the Elements of Life 2012-12-06T15:15:00.267Z Marsden had observed that when he bombarded hydrogen atoms in a sealed box with a scintillation screen with alpha particles, he predictably observed hydrogen atoms striking the scintillation screen and setting off flashes. Ernest Rutherford, master of simplicity 2013-08-30T21:45:02.847Z In addition, the smaller the nucleus, the fewer alpha particles that would hit one head on. College Physics for AP Courses 2015-08-12T00:00:00Z Long before there were accelerators available, Rutherford contrived to collect a faint beam of helium-4 nuclei, which are also called alpha particles, from a naturally radioactive material. Anti-Helium Produced 2011-04-25T16:47:00Z Inhaled and circulating to every tissue and cell, it emits alpha particles and is a powerful toxin. Threats Big and Small (2 Letters) 2011-04-11T22:12:36Z The brand new carbon-12 nuclei that are created subsequently populate the periodic table: Some stay as they are, while others fuse with another alpha particle to become oxygen. The Hoyle State: A Primordial Nucleus Behind the Elements of Life 2012-12-06T15:15:00.267Z He realized that the goal was basically one of exclusion; if he systematically exclude possible suspects that could react with the alpha particle and produce scintillations, he could determine the culprit. Ernest Rutherford, master of simplicity 2013-08-30T21:45:02.847Z Most alpha particles miss the small nuclei and are only slightly scattered by electrons. College Physics for AP Courses 2015-08-12T00:00:00Z Instead of all passing through the foil, some of the alpha particles rebounded backwards. Anti-Helium Produced 2011-04-25T16:47:00Z Plan view of the cyclotron, showing the method for obtaining an external beam of protons, deuterons, or alpha particles. LRL Accelerators The 184-Inch Synchrocyclotron These bends show where the ionizing ray, in this case an alpha particle, has been deflected by more or less direct collision with an atom. A Brief Account of Radio-activity After eliminating every source of contamination, Rutherford realized the revolutionary interpretation of the experiment; the alpha particles were interacting with the nitrogen in air to create oxygen and spit out hydrogen atoms. Ernest Rutherford, master of simplicity 2013-08-30T21:45:02.847Z By bombarding nitrogen nuclei with alpha particles from radium, he found that nitrogen was changed into oxygen. A Brief History of Element Discovery, Synthesis, and Analysis Rutherford and Geiger actually succeeded in counting the number of alpha particles emitted per second by a known mass of radium, and showed that these were charged helium atoms. The New Heavens Some experiments require an external beam of protons, deuterons, or alpha particles. LRL Accelerators The 184-Inch Synchrocyclotron Lastly, we have the production of helium from the alpha particles. A Brief Account of Radio-activity The latest theory is that the alpha particle is in fact an atom of helium, and that the final transformation product of radium and the other radioactive substances is lead. The New Physics and Its Evolution Astatine was first made at Berkeley by bombarding bismuth with alpha particles, which produced astatine and released two neutrons. A Brief History of Element Discovery, Synthesis, and Analysis The range of alpha particles from the unused active material and fissionable material of the bomb is even smaller. The Atomic Bombings of Hiroshima and Nagasaki Deuterons or alpha particles are obtained in a similar fashion using deuterium or helium gas in place of hydrogen. LRL Accelerators The 184-Inch Synchrocyclotron This means the depth or thickness of a substance necessary to put a stop to the course of the alpha particles. A Brief Account of Radio-activity The alpha particle, carrying a positive electrical charge, pulls electrons from the atoms through which it passes, while negatively charged beta particles can push electrons out of neutral atoms. Worldwide Effects of Nuclear War: Some Perspectives Radioactive elements: alpha particles from a speck of radium leave tracks on a photographic emulsion. A Brief History of Element Discovery, Synthesis, and Analysis Node:alt, Next:alt bit, Previous:alpha particles, Up:= A = alt /awlt/ 1. n. The Jargon File, Version 4.2.2, 20 Aug 2000 An alpha particle is the nucleus of a helium atom and is made up of two protons and two neutrons; it carries two positive charges. LRL Accelerators The 184-Inch Synchrocyclotron This gives the range of the alpha particles in such substances and is connected in a simple way with the atomic weight, that is, it is again fixed by the mass of the opposing atom. A Brief Account of Radio-activity The beta particle has only about one seven-thousandth the mass of the alpha particle, but its velocity is very much greater, as much as eight-tenths the velocity of light. Worldwide Effects of Nuclear War: Some Perspectives One, or possibly two alpha particles are expelled with great velocity. A Brief Account of Radio-activity Node:alpha particles, Next:alt, Previous:alpha geek, Up:= A = alpha particles n. The Jargon File, Version 4.2.2, 20 Aug 2000 Sometimes alpha particles alone are expelled, sometimes beta, or two of them together, as alpha and beta. A Brief Account of Radio-activity Helium Formed from Alpha Particles To determine the nature of the alpha particle a crucial experiment was carried out by Rutherford and Royds, which was described as follows: Fig. A Brief Account of Radio-activity As a result, beta particles can penetrate far more deeply into bodily tissue and external doses of beta radiation represent a significantly greater threat than the slower, heavier alpha particles. Worldwide Effects of Nuclear War: Some Perspectives The central system of the atom is from some unknown cause unstable, and one of the helium atoms escapes from the central mass as an alpha particle. A Brief Account of Radio-activity The first of these experimental proofs comes under the head of what is known as the scattering of the alpha particles, a phenomenon which, when first observed, proved hard to explain. A Brief Account of Radio-activity This stopping power of an atom for an alpha particle is approximately proportional to the square root of its atomic weight. A Brief Account of Radio-activity This tube, which was sealed to a larger capillary tube B, was sufficiently thin to allow the alpha particles from the emanation and its products to pass through, but sufficiently thick to withstand atmospheric pressure. A Brief Account of Radio-activity The three basic modes of radioactive decay are the emission of alpha, beta and gamma radiation: Alpha--Unstable nuclei frequently emit alpha particles, actually helium nuclei consisting of two protons and two neutrons. Worldwide Effects of Nuclear War: Some Perspectives For instance, the stopping and scattering power of the element for alpha particles has been suggested and successfully used. A Brief Account of Radio-activity Atomic Weight Losses Each alpha particle emitted means a loss of 4 in the atomic weight. A Brief Account of Radio-activity Thus from uranium with an atomic weight of 238 to radium there is a loss of three alpha particles. A Brief Account of Radio-activity On introducing the emanation into the tube, the escape of the alpha particles from the emanation was clearly seen by the scintillations produced at some distance on a zinc sulphide screen. A Brief Account of Radio-activity Lead the End Product From uranium to lead there is a loss of 8 alpha particles, or 32 units in atomic weight. A Brief Account of Radio-activity Furthermore, in the thorium series 6 alpha particles are lost before reaching the end product, which again is perhaps the chemical analogue of lead. A Brief Account of Radio-activity Ionium expels an alpha particle and becomes radium, which is a bivalent element resembling barium belonging to the second group. A Brief Account of Radio-activity Radium then expels an alpha particle and becomes the gas, radium emanation, which is an analogue of argon and belongs to the zero group. A Brief Account of Radio-activity Most of the alpha particles are propelled with such force that they penetrate some distance into the walls of the outer tube and some of these gradually diffuse out into the exhausted space. A Brief Account of Radio-activity Other instances might be cited which go to show that in all cases the loss of an alpha particle makes a change of two places toward the left or positive side of the System. A Brief Account of Radio-activity Two such losses, then, will counterbalance the loss of an alpha particle and bring the new element back to the group originally occupied by its progenitor. A Brief Account of Radio-activity Thus uranium in the sixth group loses an alpha particle and the product UX1 falls in the fourth group. A Brief Account of Radio-activity As helium is the resulting product of the alpha particles emitted by the emanation and other radio-active bodies, it is found in the soil air, soil waters, and atmosphere. A Brief Account of Radio-activity There can thus be no doubt that the alpha particle becomes a helium atom when its positive charge is neutralized. A Brief Account of Radio-activity |
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