Abstract
In recent years, neutron radiography and tomography have been applied at different beam lines at Los Alamos Neutron Science Center (LANSCE), covering a very wide neutron energy range. The field of energy-resolved neutron imaging with epi-thermal neutrons, utilizing neutron absorption resonances for contrast as well as quantitative density measurements, was pioneered at the Target 1 (Lujan center), Flight Path 5 beam line and continues to be refined. Applications include: imaging of metallic and ceramic nuclear fuels, fission gas measurements, tomography of fossils and studies of dopants in scintillators. The technique provides the ability to characterize materials opaque to thermal neutrons and to utilize neutron resonance analysis codes to quantify isotopes to within 0.1 atom %. The latter also allows measuring fuel enrichment levels or the pressure of fission gas remotely. More recently, the cold neutron spectrum at the ASTERIX beam line, also located at Target 1, was used to demonstrate phase contrast imaging with pulsed neutrons. This extends the capabilities for imaging of thin and transparent materials at LANSCE. In contrast, high-energy neutron imaging at LANSCE, using unmoderated fast spallation neutrons from Target 4 [Weapons Neutron Research (WNR) facility] has been developed for applications in imaging of dense, thick objects. Using fast (ns), time-of-flight imaging, enables testing and developing imaging at specific, selected MeV neutron energies. The 4FP-60R beam line has been reconfigured with increased shielding and new, larger collimation dedicated to fast neutron imaging. The exploration of ways in which pulsed neutron beams and the time-of-flight method can provide additional benefits is continuing. We will describe the facilities and instruments, present application examples and recent results of all these efforts at LANSCE.
| Original language | English |
|---|---|
| Article number | 45 |
| Journal | Journal of Imaging |
| Volume | 4 |
| Issue number | 2 |
| DOIs | |
| State | Published - 2018 |
| Externally published | Yes |
Funding
Acknowledgments: This work was performed under the auspices of the U.S. Department of Energy (DOE) under Contract No. DE-AC52-06NA25396 and has benefited from use of the LANSCE accelerator facility supported under the same contract. The support of the U.S. Department of Energy, Office of Nuclear Energy Nuclear Technology Research and Development program is gratefully acknowledged by SCV, AST, KJM, ATN and JTW. SCV, ASL and AST acknowledge funding from the U.S. Department of Energy, National Nuclear Security Administration’s Nonproliferation Research and Development Program (NA-22) for funding of project LB15-V-GammaDetMater-PD3Jf. The plant imaging studies presented in this article were supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project number 20130442ER. The MCP imaging system was purchased with funds from a LANL PADSTE small equipment grant. The fossil imaging was funded in part by the New Mexico Consortium. Funds were provided to cover the cost of publishing in open access. NPB gratefully acknowledges funding for a summer research fellowship from LANL’s Seaborg Institute for Plutonium and Actinide Science. The loan by James Hall of the LLNL phantoms for high energy neutron imaging is gratefully acknowledged. The majority of the research on flight-path 5 is funded by the U.S. Department of Energy’s Nuclear Energy program because neutrons, both for imaging and diffraction, are a unique probe to
Keywords
- Cold neutron
- Energy-selective
- Fast neutron
- Flat panel
- High-energy neutron
- Neutron computed tomography
- Neutron imaging
- Nuclear resonances
- Phase contrast imaging
- Thermal neutron
- Time-of-flight