Speaker
Description
Explosive astrophysical environments, such as X-ray bursts, novae and supernovae govern nucleosynthesis on the proton-rich side of the valley of stability. In these sites, nucleosynthesis proceeds mainly through p- and α- induced reactions, as well as photodisintegration reactions that push the nuclear flux away from the valley of stability. Modeling these environments requires detailed knowledge of nuclear properties and reaction rates for the nuclei involved. To address this need, direct measurements in the astrophysically relevant energy region with radioactive beams are essential. In this talk, I will present two radioactive beam experiments for explosive nucleosynthesis.
In the lighter-mass region, I will discuss one of the main breakout pathways from the hotCNO cycle towards explosive burning and the rp process, the $^{14}$O(α,p)$^{17}$F reaction. At typical burst temperatures, this reaction proceeds predominantly through a 6.15 MeV resonant state in $^{18}$Ne, that can decay through p, α or possibly 2p emission. Using the Active Target and Time Projection Chamber (ACTAR TPC) at TRIUMF, the 6.15 MeV resonance was populated through inelastic proton scattering on a radioactive $^{17}$F beam. This measurement aims to provide branching ratios between the 2p, p, and α decay channels by observing all particles in the final state.
Moving on towards the heavy elements and the astrophysical γ process, I will present the first measurement of the $^{73}$As(p,γ)$^{74}$Se reaction, one of the main destruction mechanisms of the lightest p nucleus $^{74}$Se. The measurement was performed using a radioactive $^{73}$As beam with the Summing NaI (SuN) detector at the Facility for Rare Isotope Beams. Along with the total cross-section measurement, the impact of the extracted reaction rate in the production of $^{74}$Se in Type II supernovae will be presented.