Accurate Reference Gas Mixtures Containing Tritiated Molecules: Their Production and Raman-Based Analysis

Area of Science:

• Nuclear Physics and Engineering
• Analytical Chemistry
• Materials Science

Background:

• Accurate quantification of hydrogen isotopologues (H2, D2, HD, T2, HT, DT) is vital for fusion energy, neutrino physics, and photonuclear experiments.
• Existing methods may lack the required precision for complex isotopic mixtures.
• The need for well-defined gas samples with known concentrations of both stable and radioactive isotopes is critical for research validation.

Purpose of the Study:

• To develop and validate a facility for the precise production and analysis of hydrogen isotopologue gas mixtures.
• To achieve sub-percent accuracy in relative species concentrations for both stable and radioactive isotopes.
• To establish reliable reference gas samples for critical scientific applications.

Main Methods:

• Gas sample fabrication using precise manometric gas mixing of H2, D2, and T2.
• Generation of heteronuclear isotopologues (HD, HT, DT) via catalytic reaction or beta-induced self-equilibration.
• In-line, intensity- and wavelength-calibrated Raman spectroscopy for continuous composition monitoring.

Main Results:

• A facility capable of producing well-defined gas samples with hydrogen isotopologues was established.
• Sub-percent accuracy for relative species concentrations was achieved.
• Raman spectroscopy enabled continuous monitoring and accurate determination of composition uncertainties, reaching 1% measurement and calibration accuracy.

Conclusions:

• The developed facility provides highly accurate, quantitative analyses of stable and radioactive hydrogen isotopologue mixtures.
• This capability supports advancements in deuterium-tritium fusion, neutrino mass measurements, and photonuclear experiments.
• Careful consideration of systematic effects, including wall interactions, ensured the reliability of the generated reference gas samples.