“nuclear fission”的概念、定义、翻译、参考文献-科学参考

nuclear fission

Physics

A nuclear reaction in which a heavy nucleus (such as uranium) splits into two parts (fission products), which subsequently emit either two or three neutrons, releasing a quantity of energy equivalent to the difference between the rest mass of the neutrons and the fission products and that of the original nucleus. Fission may occur without external influence (spontaneous fission) or as a result of irradiation by neutrons (induced fission). For example, the fission of a uranium–235 nucleus by a slow neutron may proceed thus:

$^{235} U + n \to^{148} La +^{85} Br + 3n$

The energy released is approximately 3×10⁻¹¹ J per ²³⁵U nucleus. For 1 kg of ²³⁵U this is equivalent to 20 000 megawatt-hours—the amount of energy produced by the combustion of 3×10⁶ tonnes of coal. Nuclear fission is the process used in nuclear reactors and atom bombs (see nuclear weapons).

https://www.nature.com/physics/looking-back/meitner/index.html Meitner and Frisch’s original paper (1939) in Nature on induced fission

Chemistry

A nuclear reaction in which the nucleus of an atom of a heavy element, such as uranium, splits into two nuclei, each of which is a lighter element. The two nuclei resulting from nuclear fission are called fission products. Two or three neutrons are frequently emitted in nuclear fission. A large amount of energy is produced, with this energy being equal to the difference between the rest masses of emitted neutrons plus the fission products and the mass of the original nucleus. Fission can occur either without any external influence, in which case it is called spontaneous fission, or by a nucleus being radiated by slow neutrons, in which case it is called induced fission.

Chemical Engineering

A nuclear reaction or a radioactive decay process. In a nuclear reaction, which forms the basis of a nuclear reactor, the exothermic reaction involves the collision of a neutron in which an atomic nucleus is divided into smaller parts together with the release of energy. Nuclear fission was discovered in 1939 by Austrian-born Swedish physicist Lise Meitner (1878–1968), German physicist Otto Hahn (1879–1968), and German chemist Friedrich Wilhelm (Fritz) Strassmann (1902–80). They discovered that the nucleus of uranium-235 could absorb a neutron and then break into two roughly equal parts with mass numbers lying between 72 and 162 and with neutrons also being emitted. During this fission there was also a loss of mass which is converted into energy according to the equation $E = m c^{2}$ where m is the mass and c is the velocity of light.

单词	nuclear fission
释义	nuclear fission Physics A nuclear reaction in which a heavy nucleus (such as uranium) splits into two parts (fission products), which subsequently emit either two or three neutrons, releasing a quantity of energy equivalent to the difference between the rest mass of the neutrons and the fission products and that of the original nucleus. Fission may occur without external influence (spontaneous fission) or as a result of irradiation by neutrons (induced fission). For example, the fission of a uranium–235 nucleus by a slow neutron may proceed thus: $^{235} U + n \to^{148} La +^{85} Br + 3n$ The energy released is approximately 3×10⁻¹¹ J per ²³⁵U nucleus. For 1 kg of ²³⁵U this is equivalent to 20 000 megawatt-hours—the amount of energy produced by the combustion of 3×10⁶ tonnes of coal. Nuclear fission is the process used in nuclear reactors and atom bombs (see nuclear weapons). https://www.nature.com/physics/looking-back/meitner/index.html Meitner and Frisch’s original paper (1939) in Nature on induced fission Chemistry A nuclear reaction in which the nucleus of an atom of a heavy element, such as uranium, splits into two nuclei, each of which is a lighter element. The two nuclei resulting from nuclear fission are called fission products. Two or three neutrons are frequently emitted in nuclear fission. A large amount of energy is produced, with this energy being equal to the difference between the rest masses of emitted neutrons plus the fission products and the mass of the original nucleus. Fission can occur either without any external influence, in which case it is called spontaneous fission, or by a nucleus being radiated by slow neutrons, in which case it is called induced fission. Chemical Engineering A nuclear reaction or a radioactive decay process. In a nuclear reaction, which forms the basis of a nuclear reactor, the exothermic reaction involves the collision of a neutron in which an atomic nucleus is divided into smaller parts together with the release of energy. Nuclear fission was discovered in 1939 by Austrian-born Swedish physicist Lise Meitner (1878–1968), German physicist Otto Hahn (1879–1968), and German chemist Friedrich Wilhelm (Fritz) Strassmann (1902–80). They discovered that the nucleus of uranium-235 could absorb a neutron and then break into two roughly equal parts with mass numbers lying between 72 and 162 and with neutrons also being emitted. During this fission there was also a loss of mass which is converted into energy according to the equation $E = m c^{2}$ where m is the mass and c is the velocity of light.
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