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).

* * *


Universalium. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • compound-nucleus model — 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

  • shell nuclear model — ▪ physics       description of nuclei of atoms by analogy with the Bohr atomic model of electron energy levels. It was developed independently in the late 1940s by the American physicist Maria Goeppert Mayer (Mayer, Maria Goeppert) and the German …   Universalium

  • nuclear model — ▪ physics       any of several theoretical descriptions of the structure and function of atomic nuclei (the positively charged, dense cores of atoms). Each of the models is based on a plausible analogy that correlates a large amount of… …   Universalium

  • coordination compound — Chem. complex (def. 10). Also called coordination complex. * * * ▪ chemistry Introduction  any of a class of substances with chemical structures in which a central metal atom is surrounded by nonmetal atoms or groups of atoms, called ligands… …   Universalium

  • Bohr, Niels — ▪ Danish physicist Introduction in full  Niels Henrik David Bohr  born Oct. 7, 1885, Copenhagen, Den. died Nov. 18, 1962, Copenhagen  Danish physicist who was the first to apply the quantum theory, which restricts the energy of a system to… …   Universalium

  • 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

  • modèle du noyau composé — 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

  • 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

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”