Measuring the ¹⁵O(α, γ)¹⁹Ne reaction in Type I X-ray bursts using the GADGET II TPC: Hardware

Abstract

Sensitivity studies have shown that the 15O(α, γ)19Ne reaction is the most important reaction rate uncertainty affecting the shape of light curves from Type I X-ray bursts. This reaction is dominated by the 4.03 MeV resonance in 19Ne. Previous measurements by our group have shown that this state is populated in the decay sequence of 20Mg. A single 20Mg(βp α)15O event through the key 15O(α, γ)19Ne resonance yields a characteristic signature: the emission of a proton and alpha particle. To achieve the granularity necessary for the identification of this signature, we have upgraded the Proton Detector of the Gaseous Detector with Germanium Tagging (GADGET) into a time projection chamber to form the GADGET II detection system. GADGET II has been fully constructed, and is entering the testing phase.

Experiments probing clustering effects in explosive nucleosynthesis

“…Mostly these involve (p, α) reactions on T z 1 2 nuclei producing α conjugate compound nuclear states with relatively strong α clusterization. Examples include (p, α) reactions on 15 N, 23 Na, 27 Al, 31 P, and 35 Cl producing compound nuclei 16 O, 24 Mg, 28 Si, 32 S, and 36 Ar, respectively (see Figure 2). These compound nuclei were found to exhibit strong clustering effects indicated by θ 2 α extracted from experiments that were many times shell-model predictions [18].…”

“…The device is currently under construction and is expected to begin measurements in 2024. Other studies of the αbranching ratio are also being pursued by the GADGET group [31,32] and using the SABRE detector [33].…”