Measurement of $d + ^7$Be cross sections for Big-Bang nucleosynthesis

TL;DR

This study measured the nuclear reaction cross sections between $^7$Be and deuterium relevant to Big-Bang nucleosynthesis, discovering a new resonance that slightly reduces predicted primordial lithium but does not resolve the lithium problem.

Contribution

The paper provides new experimental cross section data for $^7$Be + deuterium reactions, including a previously unobserved resonance within the Gamow window.

Findings

Identified a new resonance at 0.36 MeV with a strength of 1.7 keV.

The resonance reduces predicted $^7$Li abundance but does not solve the lithium problem.

Cross sections are dominated by the $(d,\,\alpha)$ reaction channel.

Abstract

The cross sections of nuclear reactions between the radioisotope $^7$Be and deuterium, a possible mechanism of reducing the production of mass-7 nuclides in Big-Bang nucleosynthesis, were measured at center-of-mass energies between 0.2 MeV and 1.5 MeV. The measured cross sections are dominated by the $(d,\alpha)$ reaction channel, towards which prior experiments were mostly insensitive. A new resonance at 0.36(5)~MeV with a strength of $\omega\gamma$ = 1.7(5)~keV was observed inside the relevant Gamow window. Calculations of nucleosynthesis outcomes based on the experimental cross section show that the resonance reduces the predicted abundance of primordial $^7$Li, but not sufficiently to solve the primordial lithium problem.