Synopsis: Unequal parts

New experiments studying nuclear fission yield unexpected results.

Traditional models of nuclear fission predict that heavy nuclei break into unequally sized (asymmetric) parts, which is consistent with the findings of most experiments in low-energy fission. This is naturally explained by the fact that one of the fragments tends to be in the vicinity of doubly magic tin-132, which is highly stable.

The vast majority of fission experiments, however, have focused on heavy nuclides ranging from thorium to fermium. Now, new experiments performed at the ISOLDE facility in CERN and presented in Physical Review Letters (Andrei Andreyev et al.), probe a different corner of the nuclear chart. The team studies mercury-180 (with 80 protons and 100 neutrons) and finds that the fission products are also asymmetric. However, in this particular case, the outcome is counterintuitive, since a symmetric decay of the nucleus into two copies of zirconium-90 (with 40 protons and 50 neutrons) would have produced exceptionally stable nuclei.

The ISOLDE team’s puzzling result hints that a very subtle interplay between macroscopic and microscopic interactions plays a deeper role in the fission process than expected and is likely to inspire detailed theoretical studies and further experiment. – Abhishek Agarwal


Features

More Features »

Announcements

More Announcements »

Subject Areas

Nuclear Physics

Previous Synopsis

Particles and Fields

In full color

Read More »

Next Synopsis

Quantum Information

Reality, locality, and “free will”

Read More »

Related Articles

Synopsis: Proton Loses Weight
Particles and Fields

Synopsis: Proton Loses Weight

The most precise measurement to date of the proton mass finds a value that is 3 standard deviations lower than previous estimates. Read More »

Viewpoint: Scattering Experiments Tease Out the Strong Force
Particles and Fields

Viewpoint: Scattering Experiments Tease Out the Strong Force

The scattering of protons from a carbon isotope can be used to test models of the strong force. Read More »

Viewpoint: Getting to the Bottom of an Antineutrino Anomaly
Particles and Fields

Viewpoint: Getting to the Bottom of an Antineutrino Anomaly

The Daya Bay Collaboration reports that sterile neutrinos probably aren’t behind a puzzling deficit in detected antineutrinos at nuclear reactors. Read More »

More Articles