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An intutitive many-body treatment is presented of the distribution in the total momentum of two gamma rays emitted in annihilation of positrons in a gas of interacting electrons. This treatment results in a momentum distribution of photon pairs which is very close to that of the ideal Fermi distribution of quasi-electrons in the electron gas. This seems to be supported by Stewart's experiment for sodium metal.
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Hatano et al. (1965) studied this question.
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