Constraining Electron Capture Rates with (d,²He) Reactions in Inverse Kinematics

Electron-capture (EC) rates play a decisive role in core-collapse and thermonuclear supernovae, the crust of accreting neutron stars in binary systems, and the final core evolution of intermediate mass stars. Charge-exchange reactions (CERs) at intermediate energies (~100 MeV) are crucial in extracting information for neutron-rich nuclei as the EC Q-values are positive for such nuclei. The differential cross sections in CERs at zero momentum transfer are proportional to the Gamow-Teller strength, B(GT), from which the EC rates can be calculated. In a first of a kind experiment, the S800 spectrometer at National Superconducting Cyclotron Laboratory (NSCL) along with Active-Target Time Projection Chamber (AT-TPC) setup was used to run an experiment with (d,²He) probe in inverse kinematics to study unstable nuclei. Data from the experiment for the ¹⁴O(d,²He)¹⁴N and ¹³N(d,²He)¹³C reactions have been analyzed to extract the differential cross section for ground and excited states and the extracted B(GT) is in good agreement with theory and existing data.