Neutron-rich matter in heaven and on Earth

Where do neutrons go? The elusive answer to such a seemingly simple question provides fundamental new insights into the structure of both atomic nuclei and neutron stars. To place the question in the proper context, consider lead-208, the element’s most abundant isotope, which contains 82 protons and 126 neutrons. As the heaviest known doubly magic nucleus, ²⁰⁸Pb holds a special place in the nuclear-physics community. Just as noble gases with filled electronic shells exhibit low levels of chemical reactivity, doubly magic nuclei with filled proton and neutron shells display great stability. Because ²⁰⁸Pb is heavy, the Coulomb repulsion among its protons leads to a large neutron excess. The Lead Radius Experiment, or PREX, at the Thomas Jefferson National Accelerator Facility in Virginia was built to measure the location of ²⁰⁸Pb’s 44 excess neutrons. In turn, a detailed knowledge of the neutron distribution in ²⁰⁸Pb illuminates the structure of a neutron star.

Full article: https://physicstoday.scitation.org/doi/10.1063/PT.3.4247

Source: https://myfusimotors.com/2019/07/24/neutron-rich-matter-in-heaven-and-on-earth/