In the Nature news item Physicists plan antimatter’s first outing — in a van an experiment to study the proposed "neutron halo" around the neutron-rich and short lived isotope 11Li is outlines:
Because antiprotons annihilate so readily, both with protons and with neutrons, they present a unique way to study the unusual configurations of radioactive nuclei. Whereas everyday atomic hearts host protons and neutrons in roughly equal measure, radioactive isotopes are stuffed with extra neutrons. This imbalance can give rise to exotic characteristics, including a surface ‘skin’ that is richer in neutrons than protons, or an extended halo in which neutrons orbit alone, as in lithium-11 (see ‘Probing a halo’). By observing how often antiprotons annihilate with a proton versus a neutron, the team will be able to understand the relative densities of these particles at the very edge of the nucleus. And because annihilation happens so rapidly, the test will be fast enough to probe even short-lived nuclei. “It’s a kind of test we haven’t been able to do before on these new, more exotic nuclei, which may have very interesting structures,” says Horowitz.
Has this interaction been modeled yet? What is it that makes researchers fairly certain that this interaction would be particularly sensitive to the last two, weakly bound "halo neutrons" as opposed to equally sensitive to all neutrons?
If it works (several years from now), perhaps it can finally answer the question Has a nuclear “neutron halo” been measured directly? Anything other than “breaks easily”?