A new excited nuclear state Available to Purchase

has been seen in unstable, neutron-rich isotopes of tin. Typically, an unexcited atomic nucleus has its constituent neutrons and protons bobbing around in a roughly spherical configuration. When excited, however, the nucleus can be made to spin, vibrate, or otherwise deform. One excited mode, called a giant dipole resonance, has the protons move in one direction while the neutrons go the other way. In neutron-rich nuclei, a tight core of nucleons can be surrounded by a diffuse halo or skin of more loosely bound neutrons. In the new experiment, the LAND collaboration at the GSI lab in Darmstadt, Germany, generated a beam of uranium-238 nuclei that then dissolved by fission into a swarm of daughter nuclei, from which the desired tin isotopes, ¹³⁰Sn and ¹³²Sn, were extracted and excited by passing through a lead target. From the debris of the subsequent decays, the researchers reconstructed the excitation energy...