(α, n) Reactions in Inverse Kinematics Using SECAR

Observations of metal poor stars in the galactic halo have found significant amounts of star-to-star

scatter in the abundances of elements around Z = 38-47. The nucleosynthesis occurring in the

neutrino driven winds of core collapse supernovae provides a possible explanation for these obser-

vations. In these explosive environments (α, n) reactions close to stability drive heavy element

enrichment. Our knowledge about the nature of this enrichment is limited by the

poorly known nuclear cross sections for these reactions.

Direct measurements of these (α, n) cross sections at astrophysical energies are therefore essential

ingredients for our nuclear and stellar models. In this talk I will discuss a novel

technique for measuring these reactions in inverse kinematics using a recoil separator to detect the

heavy reaction products in coincidence with neutrons. The first measurements of this type have

been carried out using The Separator for Capture Reactions (SECAR) located within NSCL/FRIB.

Principles of the experimental technique will be described along with a discussion of the technical

challenges of using SECAR for this specific purpose.