Publications

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Cross-sections for the elastic recoil of hydrogen isotopes, including tritium, have been measured for 4He2+ ions in the energy range of 9.0-11.6 MeV. These cross-sections have been measured at a scattering angle of 30° in the laboratory frame. Cross-sections were measured by allowing a 4He2+ beam to fall incident on solid targets of ErH2, ErD2 and ErT2, each of 500 nm nominal thickness and known areal densities of H, D, T and Er. The uncertainty in each cross-section is estimated to be ±3.2%. Published by Elsevier B.V.

Hydrogen isotope thin film standards have been manufactured at Sandia National Laboratories for use by the materials characterization community. Several considerations were taken into account during the manufacture of the ErHD standards, with accuracy and stability being the most important. The standards were fabricated by e-beam deposition of Er onto a Mo substrate and the film stoichiometrically loaded with hydrogen and deuterium. To determine the loading accuracy of the standards two random samples were measured by thermal desorption mass spectrometry and atomic absorption spectrometry techniques with a stated combined accuracy of ∼1.6% (1σ). All the standards were then measured by high energy RBS/ERD and RBS/NRA with the accuracy of the techniques ∼5% (1σ). The standards were then distributed to the IBA materials characterization community for analysis. This paper will discuss the suitability of the standards for use by the IBA community and compare measurement results to highlight the accuracy of the techniques used. © 2004 Elsevier B.V. All rights reserved.

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Controlled leak rate devices of fluoroform on the order of 10{sup -8} atm {center_dot} cc sec{sup -1} at 25 C are used to calibrate QC-1 War Reserve neutron tube exhaust stations for leak detection sensitivity. Close-out calibration of these tritium-contaminated devices is provided by the Gas Dynamics and Mass Spectrometry Laboratory, Organization 14406, which is a tritium analytical facility. The mass spectrometric technique used for the measurement is discussed, as is the first principals calculation (pressure, volume, temperature and time). The uncertainty of the measurement is largely driven by contributing factors in the determination of P, V and T. The expanded uncertainty of the leak rate measurement is shown to be 4.42%, with a coverage factor of 3 (k=3).

As part of a study to understand the long-term storage effects on scandium hydride thin films, an experiment has been conducted in which scandium dideuteride thin films were exposed to a hydrogen environment for various periods of time at ambient temperature. The resulting films were analysed using neutron reflectivity using the Surface Profile Analysis Reflectometer (SPEAR) at the Los Alamos Neutron Science Center. Using neutron reflectivity and taking advantage of the large difference in the neutron scattering lengths of hydrogen and deuterium, the resulting changes in the film composition due to isotopic exchange and diffusion were observed as a function of the film depth.