Remote imaging with MeV neutrons unlocks new possibilities

A Los Alamos-led research team has demonstrated energy-resolved neutron radiography as a powerful tool for remotely identifying isotopic compositions with megaelectron-volt (MeV)-scale neutrons. Using novel event-mode neutron imaging detectors at the FP60-R beamline at the Los Alamos Neutron Science Center (LANSCE), the team successfully identified isotopes such as carbon, silicon and oxygen based on their unique neutron cross-section signatures observed in energy-resolved transmission images.

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Why this matters: While purely demonstrative, this work represents a significant first step toward advanced neutron radiography capabilities with MeV neutrons. These developments lay the groundwork for future systems that would enhance the in-field capabilities to detect and identify nuclear materials, verify nuclear safeguards, and assess the integrity of critical components in nuclear waste storage.

What they found: 

• Isotopic identification at a distance: Fast neutron resonance radiography could distinguish isotopes of carbon, silicon and oxygen using their energy-dependent neutron cross-sections.
• Validated accuracy: Experimental data from graphite and silica (SiO₂) matched theoretical models, confirming the detector’s effectiveness.
• Advanced neutron imaging: Energy-resolved neutron techniques provide detailed spatial mapping of isotopic compositions.

Key capabilities: This breakthrough leverages time-of-flight neutron techniques to provide high-resolution isotopic imaging, enabling novel non-destructive characterization of materials with MeV neutrons.

• MeV neutron imaging for deep penetration through dense materials.
• Time-of-flight techniques for energy-sensitive elemental mapping.
• Event-mode imaging for particle discrimination and background rejection to produce true neutron radiographs

Funding: Laboratory Directed Research and Development program and NNSA's Office of Defense Nuclear Nonproliferation

LA-UR-25-21607