For the correction of losses due to true coincidences summing and edge effect, a simple method which is based on the ratio of a reference single -ray energy to that of cascade energies at near and far geometry is developed. The correction factors for several radioactive sources with simple and complex decay schemes are experimentally determined for three types of germanium detectors. It is shown that coincidence summing can be a complex effect and depends on the individual detector, the counting geometry and on the decay scheme of the radionuclide concerned.
The paper shows how, from the neutron irradiation of multi-element standards, one can derive neutron flux parameters for the irradiation position and, at the same time, greatly improve knowledge of nuclear data parameters, such as thermal cross sections, resonance integrals and gamma raz emission probabilities, for the nuclides concerned. It is then shown how the resulting neutron flux parameters and nuclear data parameters can be used to carry out neutron activation analysis without further irradiation of multi-element standards. The technique is applied to the analysis of Chinese geochemical reference material
This work shows that nuclear data and neutron flux parameters can be applied to calculate directly the elemental concentrations.
Techniques for extracting neutron flux parameters pertaining to the irradiation positions and nuclear data pertaining to the
isotopes concerned from measured reaction rates have been previously developed. This method is compared to the comparator
and relative methods of activation analysis. The principles, advantages and disadvantages of each method and sources of errors
are discussed. It also briefly discusses other factors such as accuracy and precision, sensitivity, detection limits and limit
of quantitative determination. The three methods are applied to the analysis of five environmental reference materials. The
concentrations of more than 20 elements are determined. The results show a good agreement with the certified and/or literature
Techniques for extracting neutron flux parameters pertaining to the irradiation positions and nuclear data pertaining to the isotopes concemed from measured reaction rates have been developed. An adjustment procedure based on the generalized least squares method with incorporates the, evaluated literature nuclear data, estimates of flux parameters and the experimentally measured reaction rates using high resolution -ray spectrometry is applied. More precise values of the nuclear data, i.e., thermal neutron cross sections, resonance integrals and -ray emission probabilities are thus generated. The irradiation of a multi-element standard (MES) containing 24 elements is carried out in six diffieret positions in two diverse types of reactor in the UK and Russia. It is shown that the improvement in nuclear data is revelaed in moire than 90% of the cases.
14 MeV absolute neutron activation has been tested for the elemental analysis of steel alloys. Important factors such as cross-section, neutron energy, efficiency and sources of error are discussed. The elements which could be detected with good statistics for steel and iron pipe segments were Fe, Cr, Ni, Si and Mo, and detected with low statistics were Nb and Mn. In spite of the large interference and high Fe contents the precision was about 5% except for the elements Mn and Nb which were 14% and 20%, respectively. In the standard reference material, accuracy was better for Fe, Cr, Mo, Ni and poorer for Mn and Si.
Instrumental neutron activation methods are suggested in order to carry out automatic analysis of fertilizers and plant samples for N, P, K and Si allowing for the investigation of more than 40 samples per 8 hours. The experimental errors do not exceed ±3% for N, ±6% for P, ±5% for K and ±15% for Si.