Why does this radioactive isotope gobble up neutrons?

Los Alamos scientists have fresh insights about zirconium-88

June 5, 2025

Placeholder Image
Zirconium-88 is a byproduct of nuclear reactions, including historic underground nuclear tests. Los Alamos researchers took a closer look to understand why it has an enormous neutron-capture cross section, about 30,000 times larger than expected.

A new experimental method recently helped Los Alamos scientists crack a nuclear physics mystery. The work, which gets to the crux of how the radioactive isotope zirconium-88 absorbs neutrons at an astonishing rate, is expected to advance nuclear-reaction calculations. 

Published simultaneously, one paper describes zirconium-88 research using a new instrument, and the other paper explores the origin of the isotope’s neutron-capture cross section.

Why this matters: Neutron-induced reactions are key to nuclear energy production. Understanding how nuclei absorb neutrons (known as a neutron-capture cross section) is relevant to nuclear power generation and nuclear weapons modernization, as well as fundamental science and the origin of the elements in the universe.

  • The Los Alamos technique enables the study of neutron capture on several radionuclides that may lead to future breakthroughs.
  • In a 2019 paper, Lawrence Livermore National Laboratory researchers reported that zirconium-88 has a thermal neutron-capture cross section larger than stable zirconium isotopes and the second-largest ever observed across all elements.

 

The Device for Indirect Capture Experiments on Radionuclides at LANSCE
The Device for Indirect Capture Experiments on Radionuclides at LANSCE is a new instrument designed to provide accurate data on radionuclides relevant to nuclear security that are beyond the reach of direct measurements. The first-ever binocular neutron collimation system allows the precise study of 1mm in diameter samples.

What they did: 

  • Detectors used in typical neutron-capture experiments are overwhelmed by radioactive samples, so the Los Alamos-led team developed an approach at the Los Alamos Neutron Science Center (LANSCE) that creates a buffer between the sample and the detector.
  • The team also invented a new instrument to study 1 mm diameter samples that provides the ability to probe for the first time little-understood radionuclides across a wide energy range. The Device for Indirect Capture Experiments on Radionuclides at LANSCE illuminates a sample with a beam of neutrons and then looks at what comes out the other side to see what fraction of neutrons disappeared from the beam due to sample absorption.

Funding: The work was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory and by the Office of Experimental Sciences (NA-113)/ Secondary Assessment Technologies. The Los Alamos Neutron Science Center is a National Nuclear Security Administration user facility operated for the U.S. Department of Energy.

Zirconium sample at Isotope Production Facility
For this research, the zirconium-88 sample was produced at the Lab’s Isotope Production Facility.

LA-UR-25-24868

Share

More STE Highlights Stories

STE Highlights Home
Thumbnail Covid

A cure too soon? Theoretical model explains COVID-19 rebound

Infectious virus particles still target cells despite early Paxlovid treatment

Thumbnail Cave

Exploring cave bacteria for science and education

Volunteers nurture budding scientists in microbiology, genomics and bioinformatics

Thumbnail Cint

How to create the brightest C-band single photon source at room temperature

12 million single photons are emitted per second