Jacobus Andreas Swartz

arXiv2019

Resolving the 11B(p, ${α_0}$) Cross Section Discrepancies between 0.5 and 3.5 MeV

The reaction 11B(p, 3$α$) is relevant for fields as diverse as material science, nuclear structure, nuclear astrophysics, and fusion science. However, for the channel proceeding via the ground state of 8Be, the available cross-section data shows large discrepancies of both normalization and energy scale. The present paper reports on a measurement of the 11B(p, ${α_0}$) cross section using an array of modern large area segmented silicon detectors and low beam current on an enriched thin target with the aim of resolving the discrepancies amongst previous measurements.

nucl-ex↗

arXiv2018

Measurement of the full excitation spectrum of the 7Li(p,γ)αα reaction at 441 keV

A current challenge for ab initio calculations is systems that contain large continuum contributions such as 8Be. We report on new measurements of radiative decay widths in this nucleus that test recent Green's function Monte Carlo calculations. Traditionally, γ ray detectors have been utilized to measure the high energy photons from the 7Li(p, γ)αα reaction. However, due to the complicated response function of these detectors it has not yet been possible to extract the full γ ray spectrum from this reaction. Here we present an alternative measurement using large area Silicon detectors to detect the two α particles, which provides a practically background free spectrum and retains good energy resolution. The resulting spectrum is analyzed using a many-level multi channel R-matrix parametrization. Improved values for the radiative widths are extracted from the R-matrix fit. We find evidence for significant non-resonant continuum contributions and tentative evidence for a broad 0+ resonance at 12 MeV.

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