Synopsis: Picking Nuclei with Lasers

A laser-based scheme allows the preparation of pure samples of nuclear isomers for spectroscopic analysis.
Synopsis figure
Kara M. Lynch/CERN and University of Manchester

The study of atomic nuclei with alpha, beta, and gamma-ray spectroscopy can elucidate details of nuclear structure, from the ordering of shell-model levels to the exact shape of the nuclei. Even nuclei far from stability, i.e., with short lifetimes, can be studied by creating them with nuclear reactions at large accelerators and delivering them quickly (sometimes within just 100 milliseconds) to a measurement apparatus. Although different isotopes can be separated with magnets, a great experimental challenge is posed by the fact there are often several isomers present in a beam, which makes it hard to determine which radiation came from which isomer. As reported in Physical Review X, a research team led by Kieran Flanagan of the University of Manchester, UK, has demonstrated a new method that uses isomer-selective laser ionization to isolate a pure sample of each isomer and deliver it to a spectroscopy chamber.

The scheme allowed the authors to separate different states and study in detail the neutron deficient isotopes of francium (Fr): 202-6Fr.  The nuclear g factors were also determined by resolving the hyperfine levels of each isomer’s atomic ground state.  The measurements, carried out at the ISOLDE radioactive ion beam facility at CERN, showed that, as neutrons are removed from the closed shell at N=126, Fr isotopes begin to lose their spherical shapes sooner than the corresponding Pb isotopes with the same neutron number because of the polarizability of the additional protons outside of the Z=82 shell.  The method, which should allow work with isotopes even further away from stability, opens up many new possibilities, including further studies of Fr and of other elements such as copper, polonium, and gallium. – Gene Sprouse


Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsOpticsNuclear Physics

Previous Synopsis

Statistical Physics

Liquid to Liquid

Read More »

Related Articles

Synopsis: Deep Freezing Molecules
Atomic and Molecular Physics

Synopsis: Deep Freezing Molecules

Researchers cooled trapped molecules well below 1mK—a record temperature for molecules that have not been assembled from pre-cooled atoms. Read More »

Viewpoint: Can Four Neutrons Tango?
Nuclear Physics

Viewpoint: Can Four Neutrons Tango?

Evidence that the four-neutron system known as the tetraneutron exists as a resonance has been uncovered in an experiment at the RIKEN Radioactive Ion Beam Factory. Read More »

Viewpoint: Journey from Classical to Quantum in Two Dimensions
Atomic and Molecular Physics

Viewpoint: Journey from Classical to Quantum in Two Dimensions

Two separate groups have extracted the thermodynamic equation of state for a two-dimensional gas of fermionic atoms, revealing its peculiar quantum features. Read More »

More Articles