Thin film thickness determination with neutron activation analysis.

Thickness determination of Ta2O5 thin films, deposited on the glass substrates and metallic indium and gold thin films on both glass and aluminum substrates, were performed by neutron activation analysis. Thickness determination of these thin films were made by comparing gamma-rays emitted from the radio-isotopes in the thin film with the substrate material followed by the neutron irradiations. The method led to determination of the film thicknesses without using any standard sample. A complementary optical transmission measurement was also applied on multi-layered Ta2O5 thin films for determining the individual layer densities.     

Prompt gamma-ray neutron activation analysis of boron-10 in biological materials

Prompt γ-ray neutron activation analysis of ¹⁰B concentrations in biological samples was carried out using a germanium detector and single crystal silicon filtered neutron beams from the TRIGA-II reactor.The ¹⁰B concentrations of biological samples such as tumors, tissues, blood and cultured cells were estimated from calibration curves obtained by using standard samples containing various ¹⁰B concentrations. A method of measuring absolute ¹⁰B concentrations was also presented.     

The feasibility of accelerator-based in vivo neutron activation analysis of nitrogen

The feasibility of accelerator-based in vivo neutron activation analysis of nitrogen has been investigated. It was found that a moderated neutron flux from 10 μA of 2.5 MeV protons on a ⁹Be target performed as well as, and possibly slightly better than the existing isotope-based approach in terms of net counts per unit subject dose. Such a system may be an attractive alternative to the widespread use of ^238,239Pu/Be or ²⁵²Cf neutron sources, since there is more flexibility in the energy spectrum generated by accelerator-based neutron sources. From a radiation safety standpoint, accelerators have the advantage in that they only produce radiation when in operation. Furthermore, an accelerator beam can be pulsed, to reduce background detected in the prompt-γ measurement, and such a device has a wide range of additional biological and medical applications.     

Rare-earth elements in Egyptian granite by instrumental neutron activation analysis.

The mobilization of rare-earth elements (REEs) in the environment requires monitoring of these elements in environmental matrices, in which they are mainly present at trace levels. The similarity in REEs chemical behavior makes the separate determination of each element by chemical methods difficult; instrumental neutron activation analysis (INAA), based on nuclear properties of the elements to be determined, is a method of choice in trace analysis of REEs and related elements. Therefore, INAA was applied as a sensitive nondestructive analytical tool for the determination of REEs to find out what information could be obtained about the REEs of some Egyptian granite collected from four locations in Aswan area in south Egypt as follows wadi El-Allaqi, El-Shelal, Gabel Ibrahim Pasha and from Sehyel Island and to estimate the accuracy, reproducibility and detection limit of NAA method in case of the given samples. The samples were properly prepared together with standards and simultaneously irradiated in a neutron flux of 7 x 10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The following elements have been determined: La, Ce, Nd, Sm, Eu, Yb and Lu. The gamma spectra was collected by HPGe detector and the analysis was done by means of computerized multichannel analyzer. The X-ray fluorescence (XRF) was also used.     

The influence of an additional filter in epithermal neutron activation analysis

Additional filters of tungsten and sodium in different thicknesses have been used in the epithermal neutron activation analysis of geological samples to reduce the interferences caused by resonance neutron capture in these two elements. The results show that a selective reduction of the interfering activities in favor of the activities sought can be obtained. Improvements in terms of detection sensitivity and precision in the γ-spectrometric determinations of Sc, Fe, Co, La, Sm, Eu, Gd, Tb, Yb, Lu, Th and W have been calculated.The possible applications of the filtered epithermal neutron activation analysis (FENA) method to different kinds of samples are also briefly discussed.     

Characterisation of firearms and bullets by instrumental neutron activation analysis

Instrumental neutron activation analysis was adopted to investigate the chemical composition of lead and jacketed firearms bullets.Analyses have been carried out on the most used bullets according to calibre and manufacture.The trace element content of the bullets (center and jacket) and of fragments of bullets has been utilised to identify the manufacturer.Bullets from the same manufacture have been analysed to differentiate different batches in production.