Production of Proton-rich Nuclei

Abstract

THE p-elements, those rich in protons, are less abundant than the s or r-elements by factors between 10⁻³ and 10⁻⁴, and are usually bypassed in a slow or fast neutron capturing chain. It has been suggested that they are produced either by (p, γ) or (γ, n) reactions¹. Formation by (p, γ) reactions in the envelopes of supernovae, however, would be limited by the short duration of the phenomena². Other suggestions by Ito³ and Malkiel⁴ are also inadequate. The smoothness of the abundance distribution of p-elements^5,6, however, suggests that they might have been synthesized in one physical environment, and recently there have been attempts to explain the abundances by positron capture in s-elements⁷ or by spallation processes⁸. This article is a preliminary report of an investigation of the abundance distribution of p-elements formed in a single event—the fission of highly excited nuclei in supernovae.