compound-nucleus model

compound-nucleus model

      description of atomic nuclei proposed (1936) by the Danish physicist Niels Bohr (Bohr, Niels) to explain nuclear reactions as a two-stage process comprising the formation of a relatively long-lived intermediate nucleus and its subsequent decay. First, a bombarding particle loses all its energy to the target nucleus and becomes an integral part of a new, highly excited, unstable nucleus, called a compound nucleus. The formation stage takes a period of time approximately equal to the time interval for the bombarding particle to travel across the diameter of the target nucleus (about 10−21 second). Second, after a relatively long period of time (typically from 10−19 to 10−15 second) and independent of the properties of the reactants, the compound nucleus disintegrates, usually into an ejected small particle and a product nucleus. For example, the compound nucleus silicon-28 is formed by bombarding aluminum-27 with protons (hydrogen-1 nuclei). This compound nucleus is excited, or in a high-energy state, and may decay into magnesium-24 and helium-4 (an alpha particle), silicon-27 and a proton, a more stable form of silicon-28 and a gamma-ray photon, or sodium-24 plus three protons and one neutron.

      The compound-nucleus model is very successful in explaining nuclear reactions induced by relatively low-energy bombarding particles (that is, projectiles with energies below about 50 million electron volts).

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Universalium. 2010.

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  • Compoundmodell — tarpinio branduolio modelis statusas T sritis fizika atitikmenys: angl. compound nucleus model vok. Compoundmodell, n; Zwischenkernmodell, n rus. модель промежуточного ядра, f; модель составного ядра, f pranc. modèle du noyau composé, m …   Fizikos terminų žodynas

  • Zwischenkernmodell — tarpinio branduolio modelis statusas T sritis fizika atitikmenys: angl. compound nucleus model vok. Compoundmodell, n; Zwischenkernmodell, n rus. модель промежуточного ядра, f; модель составного ядра, f pranc. modèle du noyau composé, m …   Fizikos terminų žodynas

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  • tarpinio branduolio modelis — statusas T sritis fizika atitikmenys: angl. compound nucleus model vok. Compoundmodell, n; Zwischenkernmodell, n rus. модель промежуточного ядра, f; модель составного ядра, f pranc. modèle du noyau composé, m …   Fizikos terminų žodynas

  • модель промежуточного ядра — tarpinio branduolio modelis statusas T sritis fizika atitikmenys: angl. compound nucleus model vok. Compoundmodell, n; Zwischenkernmodell, n rus. модель промежуточного ядра, f; модель составного ядра, f pranc. modèle du noyau composé, m …   Fizikos terminų žodynas

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