http://www.sciencemag.org/news/2021/04/neutron-stars-may-be-bigger-expected-measurement-lead-nucleus-suggests

Researchers bombarded lead nuclei electrons at the Thomas Jefferson National Accelerator Facility.

Say what you want about lead, it’s got a surprisingly thick skin—of neutrons, that is. In fact, the layer of neutrons on the outside of a lead nucleus is twice as thick as physicists thought, according to a new study. The seemingly abstruse result could have out-of-this-world implications: Neutron stars, the ultradense spheres left behind when stars explode in supernovae explosions, could be stiffer and bigger than theory generally predicts.