Structure of unbound neutron-rich $^{9}$He studied using single-neutron transfer

The He-8(d, p) reaction was studied in inverse kinematics at 15.4A MeV using the MUST2 Si-CsI array in order to shed light on the level structure of He-9. The well known O-16(d, p)O-17 reaction, performed here in reverse kinematics, was used as a test to validate the experimental methods. The He-9 missing mass spectrum was deduced from the kinetic energies and emission angles of the recoiling protons. Several structures were observed above the neutron-emission threshold and the angular distributions were used to deduce the multipolarity of the transitions. This work confirms that the ground state of He-9 is located very close to the neutron threshold of He-8 and supports the occurrence of parity inversion in He-9.