Synopsis: Helium Ions Give Electrons the Shake-Off

Singly ionized helium-6 is an ideal atom for testing the quantum mechanical response of electrons to a decaying nucleus.
Synopsis figure
Courtesy X. Fléchard/Caen University

The recoil and sudden change in charge of an atomic nucleus emitting a beta particle can literally shake an electron off the atom. Calculations of the probability of shake-off are most accurate when the change in nuclear potential is fast and the electron is in a hydrogenlike orbit, unperturbed by interactions with other electrons, but few reactions involve parent and daughter nuclei with such an ideal structure.

In Physical Review Letters, Claire Couratin of Caen University, France, and colleagues present the first measurement of electron shake-off in the beta decay of ionized helium-6 (6He+). With a half-life of just under a second, 6He+ beta decays into doubly ionized lithium-6 (6Li2+), a daughter nucleus in which shake-off can be described with a simple quantum mechanical calculation.

Calculations have predicted that two percent of the daughter lithium would shake off an electron, leaving 6Li3+. Couratin et al. performed a series of experiments in which they collected and confined 20,000 6He+ ions into a trap from a beam of 6He produced at France’s Large Heavy Ion National Accelerator. The trap is outfitted with detectors that measure the coincidence of beta particles and 6Li2+ and 6Li3+, allowing the team to measure the probability of shake off in 6Li2+ with a relative precision of about a percent. Their result is in excellent agreement with theory, which could make 6He+ a textbook example for experiments to come. – Jessica Thomas


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsNuclear Physics

Previous Synopsis

Atomic and Molecular Physics

Turning the Optomechanical Tables

Read More »

Next Synopsis

Related Articles

Synopsis: Detecting a Molecular Duet
Atomic and Molecular Physics

Synopsis: Detecting a Molecular Duet

Using a scanning tunneling microscope, researchers detect coupled vibrations between two molecules. Read More »

Viewpoint: How to Create a Time Crystal
Atomic and Molecular Physics

Viewpoint: How to Create a Time Crystal

A detailed theoretical recipe for making time crystals has been unveiled and swiftly implemented by two groups using vastly different experimental systems. Read More »

Viewpoint: What Goes Up Must Come Down
Atomic and Molecular Physics

Viewpoint: What Goes Up Must Come Down

A molecular fountain, which launches molecules rather than atoms and allows them to be observed for long times, has been demonstrated for the first time. Read More »

More Articles