Study of the $^{12}$B(d,p)$^{13}$B reaction with the HELIOS spectrometer

The $^{12}$B(d,p)$^{13}$B reaction has been studied in inverse kinematics at ATLAS at an energy of 6.25 MeV/u with the HELIOS spectrometer to study the positive-parity orbitals for the neutron-rich $^{13}$B nucleus. Two states previously suggested to have positive-parity at 3.48 and 3.68 MeV were resolved and their proton angular distributions measured. The $^{11}$B(d,p)$^{12}$B reaction was also studied as a reference standard. The angular distribution for the 3.48 MeV state is consistent with an l=0 transition as expected from shell-model calculations which suggest a 1/2$^{+ }$state that is primarily an s$_{1/2}$ neutron coupled to the 1$^{+}$ ground state of $^{12}$B. The 3.68-MeV angular distribution is dominantly l=2 (with a slight l=0 admixture), consistent with the shell-model expectation of a 3/2$^{+ }$state, although the spectroscopic factor relative to that for the 3.48-MeV state is much smaller than the shell-model prediction.