Neutron Depth Profiling: Overview and Description of NIST Facilities.
R G Downing1, G P Lamaze1, J K Langland1
1National Institute of Standards and Technology, Gaithersburg, MD 20899.
Summary
The new Cold Neutron Depth Profiling (CNDP) instrument offers enhanced sensitivity for nondestructive material analysis. This allows for precise measurements of elemental profiles, such as 17O, previously unattainable.
Area of Science:
- Materials Science
- Nuclear Physics
- Analytical Chemistry
Background:
- The NIST Cold Neutron Research Facility (CNRF) has developed a new instrument for advanced material analysis.
- Existing thermal depth profiling instruments have limitations in sensitivity.
Purpose of the Study:
- To introduce the operational status and capabilities of the Cold Neutron Depth Profiling (CNDP) instrument.
- To demonstrate the neutron depth profiling (NDP) technique with practical examples.
- To provide a comprehensive bibliography of NDP research.
Main Methods:
- Utilizing a cold neutron beam from a D2O ice cold source, filtered through single crystal sapphire.
- Employing a sample chamber with remote scanning of 150 × 150 mm areas and adjustable sample/detector angles.
- Characterizing the neutron energy spectrum with a 65 K Maxwellian distribution.
Main Results:
- The CNDP instrument is now operational at CNRF.
- Achieved improved sensitivity compared to existing thermal depth profiling methods.
- Successfully performed the first nondestructive measurements of 17O profiles.
Conclusions:
- The CNDP instrument represents a significant advancement in nondestructive elemental analysis.
- The enhanced sensitivity enables new research possibilities, including the study of isotopes like 17O.
- The described NDP technique and instrument are valuable tools for materials research.
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