An automated device for the analysis of uranium is described. The analyser comprises a sample transfer system, a neutron counter,
a microprocessor and a teletype. A set of 100 samples, 14 ml of maximum volume, is analysed without manual intervention. The
capacity is 45 samples per hour. Using a 10 g sample the detection limit is 0.06 ppm and uranium concentrations of 1 ppm can
be determined with a precision of better than ±5%. The only source of systematic error is thorium the sensitivity of thorium
being 2.3% of that of uranium. Results for USGS standard rocks are reported and the cost of the analysis is discussed.
A method for simultaneous determination of uranium and thorium based on the deviation of their fission cross-section curves has been developed. Using a D-T neutron generator two different neutron spectra were produced with and without moderator around the target. The detection limits were found to be 0.044 mg and 0.25 mg in the presence of a moderator, while for fast neutrons 0.017 mg and 0.037 mg for uranium and thorium, respectively.
In the present paper the method of the equivalent differential-operator equation has been applied in the study of the existence
and asymptotic representation of periodic solutions of autonomous systems of the form
This paper is meant to re-examine the relative (and, at some points, absolute) chronology of some Early Greek changes of the occlusive phonemes (i.e. devoicing of Proto-Indo-European voiced aspirates, assibilation and palatalizations) and to point out some apparent questions and problems concerning the occlusive system as a whole.
A novel technique for the determination of Pt and Au at low concentrations is described. The method involves /K/ X-ray spectrometry preceded by fast neutron activation of the stable isotopes of the elements of interest. A full appraisal of the technique is presented for the analysis of small powdered samples. The sensitivity was optimized by employing a detector that was particularly effective at energies below 150 keV. The investigation formed the basis of a feasibility study which was utilized to establish if the application could be developed for the routine off-line determination of Pt and Au. We show that the method does not necessarily depend on the sample matrix, and that it proves to be a strong rival to conventional activation analysis.