Enhancement of Nucleosynthesis Reaction Rates due to Nonthermalized Fast Neutrons

Yuri V. Petrov and Alexander I. Shlyakhter

The Astrophysical Journal, 327: 294-297, 1988 April 1


It is usually assumed in stellar nucleosynthesis calculations that neutrons are completely thermalized. Hence, if the cross section of a neutron-induced reaction has a threshold, or it is suppressed by the Coulomb barrier in the exit channel, the reaction rate is quite low. However, the contribution from the decelerating fast neutrons has been neglected previously. We show that, though the fraction of such neutrons is small, they enhance a number of nucleosynthesis reaction rates by many orders of magnitude, especially at low temperatures.

Keywords: nucleosynthesis

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Related recent work:

THE ROLE OF EPITHERMAL NEUTRONS IN AGB STARS: BORON SYNTHESIS, by A. I. Shapiro. We consider the influence of the absorption of epithermal neutrons on the nucleosynthesis in asymptotic-giant-branch stars (the Petrov-Shlyakhter effect). We show that epithermal neutrons can be captured by nitrogen through the hitherto unanalyzed channel 14N(n, a)11B. Since the proton density in the zone of partial mixing is low, this process results in an appreciable boron density. This boron can be dredged up to the stellar surface by peculiar processes.We analyze the boron density as a function of the assumed parameters for the zone of partial mixing.

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