Direct measurements of astrophysical reactions using the DRAGON recoil separator

Determining the stellar origin of the elements observed in our Galaxy today poses one of the key challenges in the field of nuclear astrophysics. Thus, we seek to understand the nuclear processes involved in stellar evolution, as their details give us insight into the fusion pathways and routes to the synthesis of heavy elements. The investigation of radiative capture reactions involving the fusion of hydrogen or helium is crucial for the understanding of said nucleosynthesis pathways as these reactions govern nucleosynthesis and energy generation in a large variety of astrophysical burning and explosive scenarios. However, direct measurements of the associated reaction cross sections at astrophysically relevant low energies are extremely challenging due to the vanishingly small cross sections in this energy regime. Additionally, many astrophysically important reactions involve radioactive isotopes, which pose challenges for beam production and background reduction.

To overcome these challenges, the DRAGON (Detector of Recoils And Gammas Of Nuclear Reactions) recoil spectrometer at the TRIUMF-ISAC Radioactive Ion Beam Facility has been designed to directly measure radiative capture reactions of importance for nuclear astrophysics in inverse kinematics [1,2]. To date DRAGON still holds the record for the number of direct measurements of radiative capture reactions performed with radioactive ion beams world-wide.

In this contribution, I will give a brief overview of specifications and operation of the DRAGON recoil separator before presenting recent experimental highlights including the first direct measurement of an astrophysical reaction using a radioactive beam of isomeric nuclei, as well as future upgrades to the facility.