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

• Main Authors: Michael Munch, Oliver Sølund Kirsebom, Jacobus Andreas Swartz, Karsten Riisager, Hans Otto Uldall Fynbo
• Format: Article
• Language: English
• Published: Elsevier 2018-07-01
• Series: Physics Letters B
• Online Access: http://www.sciencedirect.com/science/article/pii/S0370269318304611

A current challenge for ab initio calculations is systems that contain large continuum contributions such as Be8. 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 Li7(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 12MeV. Keywords: Ab initio, R-matrix, Be8, Radiative decay width, Light nuclei