# Synopsis: Far from the stable nuclei

An advance in computational techniques for performing nuclear shell model calculations points to an island of inversion near chromium-$64$.

Nuclei further and further from the line of stability are being widely studied using beams of unstable nuclei. The shell model provides an excellent description of nuclear structure, but its predictions are most powerful when it includes many active nuclear orbits and a realistic description of the effective interaction between the active nucleons. This requires time-consuming computations that can handle huge amounts of data.

Writing in Physical Review C, Silvia Lenzi at the National Institute of Nuclear Physics (INFN) in Padova, Italy, and colleagues in France and Spain, report a significant computational advance—involving matrix dimensions reaching ten billion—in shell-model calculations. Starting with a core nucleus of calcium-$48$, they include the remaining proton and neutron orbits from the $p\phantom{\rule{0}{0ex}}f$ major shell, and the ${g}_{9/2}$ and ${d}_{5/2}$ orbits for neutrons from the next major shell, to study neutron-rich nuclei that are centered around chromium-$64$. In particular, they explore a possible “island of inversion,” where the neutron $d\phantom{\rule{0}{0ex}}g$ orbits are filled in preference to the $p\phantom{\rule{0}{0ex}}f$ ones.

Lenzi et al. also calculate the allowed states of the nuclei as pairs of protons are removed from nickel-$68$ and find a rapid onset of deformation (changes in the nuclear shape). The deformation is signaled by a decrease in the excitation energy of the first excited state (denoted by ${2}^{+}$) and a concomitant increase in the transition strength to the ground state. Their calculations point to an island of inversion that is similar to the one seen near magnesium-$32$. Lenzi et al. are able to reproduce the evolution of deformation along various isotopic chains, suggesting they have achieved a comprehensive description in terms of the shell model. – John Millener

### Announcements

More Announcements »

Nuclear Physics

## Previous Synopsis

Particles and Fields

## Next Synopsis

Superconductivity

## Related Articles

Nuclear Physics

### Synopsis: Throwing Nuclei in the Ring

By trapping nuclei in a particle storage ring, researchers characterize previously inaccessible nuclear reactions that take place in stellar explosions. Read More »

Optics

### Viewpoint: Cavity with Iron Nuclei Slows Down X Rays

Slow light effects have been measured for x rays using a cavity filled with iron nuclei, where the speed of light was reduced by a factor of 10,000. Read More »

Particles and Fields

### Viewpoint: Cyclotron Radiation from One Electron

An electron’s energy can be determined with high accuracy by detecting the radiation it emits when moving in a magnetic field. Read More »