The Interaction of Neutrons With 7Be: Lack of Standard Nuclear Physics Solution to the "Primordial 7Li Problem"

TL;DR

This study measured neutron reaction cross sections on 7Be to evaluate if standard nuclear physics can resolve the primordial 7Li abundance discrepancy, finding it insufficient for a solution.

Contribution

The paper provides new experimental MACS data for 7Be reactions at BBN energies, challenging the viability of standard nuclear physics solutions to the 7Li problem.

Findings

Measured MACS of 7Be(n,p), (n,a), and (n,ga) reactions at 49.5 keV.

Results indicate standard nuclear physics cannot explain the primordial 7Li abundance.

Supports the need for alternative explanations beyond standard nuclear physics.

Abstract

The destruction of 7Be with neutrons represents the last possible standard avenue to reduce the predicted abundance of the primordial 7Li and in this way to attempt to solve the Cosmological 7Li problem. We discuss the results of an experiment performed at the Soreq Applied Research Accelerator Facility (SARAF) in Israel where we measured the Maxwellian Averaged Cross Sections (MACS) of the 7Be(n,p), 7Be(n,a), and 7Be(n,ga) reactions. Our MACS measured at 49.5 keV in the window of the Big Bang Nucleosynthesis (BBN), indicate the lack of standard nuclear physics solution to the "Primordial 7Li Problem".