Exploring the spin states of ⁹⁰Zr populated by (p,p'), (p,d), and (p,t) reactions

The ⁹⁰Zr nucleus was produced by three different reactions: ⁹⁰Zr(p,p'), ⁹¹Zr(p,d), and ⁹²Zr(p,t), and the spin-parity (J^π) population of the ⁹⁰Zr states produced by these reactions was studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as ⁸⁹Zr(n,γ). Discrete γ-rays, associated with the de-excitation of ⁹⁰Zr and ⁸⁹Zr, were measured in coincidence with light ions at ⁹⁰Zr excitation energies extending above the neutron separation energy. Low-lying states populated by (p,d) and (p,t) reactions agreed well with the previous measurements. The measured γ transition systematics were used to gain insights into the J^π distribution of ⁹⁰Zr around the neutron separation energy and it was found that the (p,p') reaction preferentially produces lower J states than (p,d) and (p,t) reactions in the studied energy region. (authors)