Angle-integrated cross-section measurements of the $^{ 56}$Ni(d,n) and (d,p) stripping reactions have been performed to determine the single-particle strengths of low-lying excited states in the mirror nuclei pair $^{ 57}$Cu-$^{ 57}$Ni situated adjacent to the doubly magic nucleus $^{ 56}$Ni. The reactions were studied in inverse kinematics utilizing a beam of radioactive $^{ 56}$Ni ions in conjunction with the GRETINA $\gamma$-array. Spectroscopic factors are compared with new shell-model calculations using a full $pf$ model space with the GPFX1A Hamiltonian for the isospin-conserving strong interaction plus Coulomb and charge-dependent Hamiltonians. These results were used to set new constraints on the $^{ 56}$Ni(p,$\gamma$)$^{ 57}$Cu reaction rate for explosive burning conditions in x-ray bursts, where $^{ 56}$Ni represents a key waiting point in the astrophysical rp-process.
Categories: nucl-ex astro-ph.SR nucl-th