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U.S. Department of Energy
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Advanced mass spectrometers for hydrogen isotope analyses

Technical Report ·
OSTI ID:6486313

Two advanced prototype mass spectrometers for the accurate analysis of mixtures of the hydrogen isotopes were evaluated. One, a VG-Isotopes GAZAB, was developed for the Mass Spectrometer Technical Group, a group representing ten DOE contractors. The other, a MAT 250 HDT, was developed independently by Varian MAT (now Finnigan MAT) after extensive discussions with Du Pont personnel. The GAZAB is a large double-focusing instrument with a resolution of 2000 at mass 4 and an abundance sensitivity of > 100,000 for the HT-D/sub 2/ doublet. The MAT 250 HDT is a smaller, simpler, stigmatic focusing instrument with exceptionally high ion intensities (> 1 x 10/sup -9/ A at 600 and about 1 x 10/sup -10/ A at 1300 resolution) for high signal-to-noise ratios. Both instruments are computer controlled. Once a scan is started, peak switching, scanning, mass discrimination control, data collection and data reduction are done without operator intervention. Utility routines control hysteresis effects and instrument calibration. A containment facility, with dual inlet systems and a standard distribution system, permits testing with tritium mixtures. Helium flow standards and tritium activity meters provide independent verification of the mass spectrometer calibrations. A recovery system prevents the release of tritium to the environment. The performance of the mass spectrometers was essentially equal under simulated process control conditions. Precision and accuracy for the D/T ratio was < 0.5% (rel 2sigma limits). Performance factors were: sample equilibration < 300 ppM; linearity within +- 0.3%; and gas interference < 0.1%. Mass discrimination was controlled reliably by the computers. Therefore, single focusing instruments are suitable for routine control laboratory operations. Double-focusing instruments are only needed for special applications. SRL/SRP personnel worked closely with both manufacturers in this program.

Research Organization:
Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.
DOE Contract Number:
AC09-76SR00001
OSTI ID:
6486313
Report Number(s):
DP-1674; ON: DE85000716
Country of Publication:
United States
Language:
English