Probability of y-ray emission

The probability of y-ray emission or absorption by a nucleus is proportional to the square of the matrix element i/q> between the final, ij/f,... 

The probability of y-ray emission is given by the sum of the probabilities for the emission of the individual multipole radiations, which decrease drastically with increasing L. Furthermore, for a certain multipole, the probability of the emission of electric multipole radiation is about two orders of magnitude higher than that of the emission of magnetic multipole radiation. 

On the basis of the shell model of the nuclei, Weisskopf derived the following equations for the probabilities of y-ray emission, given by the decay constants Xe for electric multipole radiation and Am for magnetic multipole radiation ... 

If the energy of the transition is greater than 1.022 MeV, the nucleus may lose its excitation energy also by internal electron-positron pair emission. The probability of this mechanism is low it is usually more than 10 times smaller than the probability of y-ray emission. In contrast with the internal conversion electron emission, the internal pair formation coefficient increases with increasing y-ray energy and decreases with increasing atomic number and multipolarity of transition. A review of internal pair formation was given by Wilson (1965). 

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See also in sourсe #XX -- [ , , , ]

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