Speaker
Description
A new instrument for Prompt Gamma Neutron Activation Analysis (PGNAA) has been installed at the RA-6 (1 MW) research and training reactor located at the Bariloche Atomic Centre (San Carlos de Bariloche, Argentina). This non-destructive elemental analysis technique enables the determination of major components and is particularly useful for quantifying B, Cd, Sm and Gd at trace levels, as well as H as a minor component. The samples, which are analysed using gamma radiation emitted by thermal neutron activation, do not require any special preparation, and it is possible to analyse up to a few grams of both solid and liquid samples.
The RA-6 instrument, which has been named the Prompt Gamma Analyser, or ‘AnGI’ from Spanish translation, utilises radial channel #2, inside which sapphire and bismuth filters, as well as lead and boronated polyethylene collimators, have been installed to optimise the extraction of thermal neutron radiation. The beam passes through a lead shield lined internally with natural LiF and is ultimately absorbed by a beam catcher. The sample is introduced into this shielding via a top port and the emitted gamma radiation is measured by a high-resolution gamma spectrometer through a side opening. The spectrometry system comprises a type-N germanium detector and a NaI(Tl) Compton suppression ring, which are time-synchronized. The conventional thermal neutron flux on the sample is 9×10⁵ n/cm²·s and the distance between the sample and the germanium detector is 40 cm. The gamma background has a count rate of 150 cps across the entire spectrum of 8 MeV. Spectral analysis is carried out using the Hypermet-PC programme.
The facility now makes it possible to extend the RA-6’s training capacity to include students from the Balseiro Institute, and applications have been developed for the analysis of medicinal glass, geological and archaeological samples and nuclear materials.
Key Words
PGNAA, PGAA, Research reactor, Neutron beam