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Reference | Abstract | Physics

Measuring the 15O(α,γ)19Ne Reaction Rate in Type I X-ray Bursts using 20Mg ꞵ-decay

Heavy Ion Discussion Group, 13 October 2023, 10:00 p.m.

Title: Measuring the 15O(α,γ)19Ne Reaction Rate in Type 1 X-ray Bursts using 20Mg β decay

Speaker: Tyler Wheeler, Michigan State University

(Host: Melina Avila, PHY)
Abstract: A neutron star can accrete hydrogen-rich material from a low-mass binary companion star. This can lead to periodic thermonuclear runaways, which manifest as Type I X-ray bursts detected by space-based telescopes. Sensitivity studies have shown that 15O(α, γ)19Ne carries one of the most important reaction rate uncertainties affecting the modeling of the resulting light curve. The 15O(α, γ)19Ne reaction also plays a pivotal role in determining the composition of X-ray burst ashes. This reaction is expected to be dominated by a resonance corresponding to the 4.03 MeV excited state in 19Ne. This state has a well-known lifetime, so only a finite value for the small alpha-particle branching ratio is needed to determine the reaction rate. Previous measurements have shown that this state is populated in the decay sequence of 20Mg. 20Mg(ꞵpα)15O events through the key 15O(α, γ)19Ne resonance yield a characteristic signature: the emission of a proton and alpha particle. To identify these events of interest the GADGET II TPC was used at the Facility for Rare Isotope Beams during Experiment 21072. An 36Ar primary beam was impinged on a 12C target to create a fast beam of 20Mg that fed the 19Ne state of interest. The details of the upgraded GADGET II system will be discussed along with the preliminary results from this experiment, which include discussion of the data processing and analysis methods being used on the newly acquired data, as well as a primer on the development of convolutional neural networks for rare event identification.