No abstract available

[en] A possible relation between the effective resonance energy and the infinite dilution resonance integral of (n,γ) reactions is discussed. These two parameters are important data in thermal neutron activation analysis when using the single comparator method based on the Hoegdahl convention. The values for the these two parameters of more than one hundred (n,γ) reactions are considered, and the possibility of a - 2/3 power function is proposed. (author)

No abstract available

[en] The sample container avoids contaminating the sample substance by diffusion of foreign matter from the wall of the sample container into the sample. It cannot be activated, so that the results of measurements are not falsified by a radioactive container wall. It consists of solid carbon. (orig./HP)

[en] Although it is possible to understand each of the basic processes taking place in a liquid scintillation counter, the number of parameters involved, the complex way in which they interact with each other and the difficulty in assessing some of them quantitatively make it virtually impossible to give an accurate mathematical description of the complete liquid scintillation counting process. However, even imperfect mathematical models may eventually become helpful in understanding certain aspects of this process and possibly lead to improvements in measuring methods or instrument design. In recent years, various models have been proposed. The mathematical model presented in this study is a 3-dimensional extension of the model discussed earlier by one of the authors (F.E.L. ten Haaf, in Liquid Scintillation Counting, Vol.2 (eds. M.A.Crook, P.Johnson and B.Scales), Heyden, London 1972,pp.39-48). It is used to generate probability distributions representing pulse height distributions from differently quenched liquid scintillation samples. These are compared with experimentally obtained pulse height distributions. Calculated channels-ratio calibration curves, based on the pulse height distributions produced by the model, are compared with experimentally obtained channels-ratio curves. (author)

No abstract available

[en] This paper deals with relational equations between the Hogdahl and the Westcott convention for those (n, γ) reactions for which the Westcott g-factor equals unity. It is the aim of this article to give a more clearly structured understanding of both conventions at their use in neutron activation analysis. (author) 11 refs

[en] Published in summary form only

[en] The off-line system for instrumental neutron activation analysis is carried out in two stages. Each sample is measured four times, e.g. about 3 hours, 1 day, 1 week and 1 month after irradiation and in the Ge(Li)-spectra the peaks are determined by the computer program PAP (photopeak analysis program). Thereafter the data of the peaks from the four spectra of each sample are collected and the identification of the nuclides is carried out. Simultaneously the element contents are calculated (NAAP, neutron activation analysis program). Thus, the practical features described in this article fall into two groups, viz. those which are part of the spectrum evaluating program (PAP) and those which belong to the second stage, the qualitative and quantitative analysis (NAAP). The first group consists of a correction method for random coincidence losses in the amplifier system of the spectrometer and a method for determining the detection limit. To the second group belongs a set of standardized measuring conditions including correction for cascade summing and transmission through a lead absorbent. Special correction methods for the interference of the Cu analysis by ²⁴Na, the burn-up of the radioactive nuclide formed and the interference of the Pt determination by Au are also given. (T.G.)

[en] The characteristic neutron spectrum parameters: thermal neutron flux, epithermal flux/thermal flux ratio (cadmium ratio), epithermal flux distribution parameter α for thermal neutron activation analysis were determined for the most important irradiation positions of 4 reactors. Experiences with the method of determination is described. The final results show that the overall uncertainty in the flux ratio and in the cadmium ratio is at most 5% with this method. This confirms the supposition that the cadmium ratio is a stable parameter for a long period. The overall uncertainty in α is much greater, varying from up to 80% for very low values of α to at most 30%. (author) 18 refs.; 2 tabs