Observation of T=3/2 isobaric analog states in Be9 using p+Li8 resonance scattering

Background: Resonance scattering has been extensively used to study the structure of exotic, neutron-deficient nuclei. Extension of the resonance scattering technique to neutron-rich nuclei was suggested more than 20 years ago. This development is based on the isospin conservation law. In spite of broad field of the application, it has never gained a wide-spread acceptance.Purpose: To benchmark the experimental approach to study the structure of exotic neutron-rich nuclei through resonance scattering on a proton target.Method: The excitation function for $p+^{8}\mathrm{Li}$ resonance scattering is measured using a thick target by recording coincidence between light and heavy recoils, populating $T=3/2$ isobaric analog states (IAS) in $^{9}\mathrm{Be}$.Results: A good fit of the $^{8}\mathrm{Li}(p,p)^{8}\mathrm{Li}$ resonance elastic scattering excitation function was obtained using previously tentatively known $5/{2}^{\ensuremath{-}}\phantom{\rule{4pt}{0ex}}T=3/2$ state at 18.65 MeV in $^{9}\mathrm{Be}$ and a new broad $T=3/2\phantom{\rule{4pt}{0ex}}s$-wave state---the $5/{2}^{+}$ at 18.5 MeV. These results fit the expected isomirror properties for the $T=3/2\phantom{\rule{4pt}{0ex}}A=9$ isoquartet.Conclusions: Our analysis confirmed isospin as a good quantum number for the investigated highly excited $T=3/2$ states and demonstrated that studying the structure of neutron-rich exotic nuclei through IAS is a promising approach.