Abrupt changes in atomic nucleus properties at magic number

Amazing stuff! Science is not without its moments! 😄 Will new nuclear theories be needed?

"... to measure how the nuclear electromagnetic properties of indium isotopes evolve when an extreme number of neutrons are added to the nucleus. These nuclei do not exist in nature, and once created, their lifetimes [are extremely short] ... 
When measuring a [exotic nuclei] with a certain “magic” number of neutrons — 82 — the magnetic field of the nucleus exhibited a drastic change, and the properties of these very complex nuclei appear to be governed by just one of the protons of the nucleus. ...
The motion of protons and neutrons orbiting inside the atomic nucleus generates a magnetic field, effectively turning the nucleus into a femtometre-scale (one-quadrillionth of a meter) magnet. Understanding how nuclear electromagnetism emerges from the underlying fundamental forces of nature is one of the major open problems of nuclear physics. ..."

"In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular ‘magic’ numbers of nucleons, nuclear properties are governed by a single unpaired nucleon. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics. The indium isotopes are considered a textbook example of this phenomenon, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 ... To investigate the microscopic origin of these observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons."

A new spin on nuclear magnetic moments | MIT News | Massachusetts Institute of Technology New results from researchers at MIT reveal an unexpected feature of atomic nuclei when a “magic” number of neutrons is reached.

Nuclear moments of indium isotopes reveal abrupt change at magic number 82