Measurement of Alpha Capture Reactions on 10,11B

The nucleosynthesis in first generation stars is characterized by a completely different nucleosynthesis reaction pattern due to the lack of heavier nuclei impurities. Without the carbon, nitrogen, and oxygen that allow the CNO-cycle, these stars would have to only rely on the inefficient pp-chains for their energy production. However, there may exist other reaction chain sequences that utilize only light elements acting as alternative pathways to convert primordial hydrogen, helium, and lithium isotopes to heavier nuclei. Two possible reaction chains are 2H(α, γ)6Li(α, γ)10B(α,n)13N and 7Li(α,γ)11C(βν) 11B(α,n)14N. A detailed understanding of the 10,11B(α,n)13,14N reactions are crucial in determining the possibility of these two reaction chains. In this work, a series of measurements of the 10B(α,n)13N reaction and the 11B(α,n)14N reaction are conducted at the Nuclear Science Laboratory (NSL) of the University of Notre Dame. The measurements of the 11B(α,n)14N reaction utilizes a standard 3He counter, while those of the 10B(α,n)13N are made with a state-of-the-art deuterated liquid scintillator. In addition, excitation curves were also measured for the 10B(α, p1,2,3γ)13C reactions using a high-purity germanium detector (HPGe). R-matrix analyses are performed for both reactions in order to facilitate a comparison of the underlying nuclear structure with reaction measurements.