Measurement of hydrogen in advanced materials by cold neutron prompt gamma-ray activation analysis

An instrument for cold neutron prompt gamma-ray activation analysis (PGAA), located at the NIST Center for Neutron Research (NCNR), has proven useful for the measurement of trace hydrogen in advanced materials. Samples are irradiated by a beam of neutrons extracted from the reactor core; gamma rays emitted upon neutron capture are measured by a high purity germanium detector. The detection limit for hydrogen is less than 10 mg/kg for most materials. PGAA has been used to study hydrogen in a wide variety of materials, including titanium alloys, RF superconducting niobium cavities, and semiconductor materials. The technique has also been used to measure hydrogen uptake by solid proton conductors and hydrogen storage materials. A future upgrade to the instrument will improve detection limits and applicability of the method.