Spectroscopy of low-lying d+⁷Be resonances through coincident detection of decay particles

The abundance of lithium in Big Bang Nucleosynthesis provides an important constraint for cosmology and metal-poor stars. Nuclear physics experiments have determined the most important reaction rates in the Big Bang Nucleosynthesis (BBN) network, but secondary reactions require further study. Specifically, branching ratios of highly excited states of ⁹B, which serve as resonant states for d+⁷Be, have been of interest to investigate the destruction of A=7 nuclei. Previous studies performed at the Fox Laboratory at Florida State University populated the ⁹B states through ¹⁰B(³He, alpha) and used the Super-Enge Split-Pole Spectrograph (SE-SPS) and Silicon Array for Branching Ratio Experiments (SABRE) to determine the excitation spectrum and decay branching ratios. There, indications for a possible new excited state at 16.641(17) MeV were found in the ⁷Be + ²H channel, which could have significant impact on the BBN reaction rate, but could not be unambiguously established. A new experiment was performed with the same reaction to investigate this state, adapting SABRE to a different geometric configuration designed to detect ⁷Be and ²H in coincidence, thus distinguishing it from other possible background reactions. This presentation discusses the preliminary results of this experiment.