Bubble-like nucleus discovered with the help of Hungarian researchers

An international research group discovered a bubble like nucleus distribution in a silicon isotope with extra neutrons (34Si). In this isotope, the central proton density is almost half the proton density at the periphery of the nucleus, while neutron density is balanced. The experiment was conducted on a radioactive ion beam and researchers at the MTA Atomki, Debrecen were among the scientists who partook in the analyses of the data.

19 December, 2016

Many properties of the atomic nucleus, such as vibrations, rotations and incompressibility, can be interpreted as due to a two-component quantum liquid of protons and neutrons.

Electron scattering measurements on stable nuclei demonstrate that their central densities are saturated, as for liquid drops. In exotic nuclei near the limits of mass and charge, with large imbalances in their proton and neutron numbers, the possibility of a depleted central density, or a ‘bubble’ structure, has been discussed in a recurrent manner since the 1970s.

Here we report first experimental evidence that points to a depletion of the central density of protons in the short-lived nucleus 34Si. The proton-to-neutron density asymmetry in 34Si offers the possibility to place constraints on the density and isospin dependence of the spin–orbit force—on which nuclear models have disagreed for decades—and on its stabilizing effect towards limits of nuclear existence.

The results were published in Nature.