This table enables a quick estimate of the primary reaction interferences which can occur in 14-MeV neutron activation analysis
for all determinable elements throughout the periodic system. Published experimental cross-sections, and cross-sections estimated
by semiempirical formulae and systematics were used to calculate the ratio of the radioactivity produced from the element
to be determined via the principal reaction and of the radioactivity produced via the primary interference reaction for three
energy intervals between 14 MeV and 15 MeV. Also listed are the used cross-section data and abundances of the appropriate
isotopes for both the element to be determined and the interfering element, as well as the half-lives of the indicator radionuclides.
Proton activation analysis has been applied to develop a procedure for the simultaneous determination of chromium, nickel
and copper. The procedure involves the bombardment of the sample with protons to induce52Cr(p, n)52mMn,60Ni(p, n)60Cu and63Cu(p, n)63Zn reactions. These reactions have been studied for proton energies from 11 MeV to 15 MeV. Thick target yields for the production
of the indicator radionuclides as well as the sensitivities of the determination have been measured in this energy region
and are compared with results obtained for other charged particle induced reactions. Detailed data are given on nuclear and
instrumental interferences. The trace elements have been determined nondestructively and simultaneously in cobalt with a relative
precision of 8 to 15%.
Instrumental and radiochemical neutron activation analysis has been applied to a comprehensive trace characterization of AlSiCu sputter targets. By instrumental neutron activation analysis via long-lived indicator radionuclides, up to 33 elements were assayed with detection limits between 0.01 and 200 ng·g–1. The high activity of64Cu and24Na produced from the matrix significantly limits the instrumental performance via short- and medium-lived indicator dionuclides. For this reason, a radiochemical separation was developed based on adsorption of24Na on hydrated antimony pentoxide and extraction of64Cu by diethylammonium diethyldithiocarbamate from HCl medium. By this radiochemical method, As, Ga, K, La, Mn, Mo, Re, Sb, U and W could be assayed via medium-lived radionuclides and the achievable limits of detection were between 0.1 and 25 ng·g–1. Further improvement of detection limits for U and Th was achieved by a selective radiochemical separation of239Np and233Pa on a Dowex 1×8 column in HF and HF/NH4F medium providing limits of detection for U and Th of 0.06 and 0.02 ng·g–1, respectively. These techniques were applied to the analysis of two AlSiCu sputter target materials. Results are compared with those of glow discharge mass spectrometry.
Distribution ratios for As(V), Fe(III), Sb(V), Sc, Sn(IV), Mo, W, Tc(VII) and Re(VII) in the system Dowex-1X8 and 0.1–11.5M HCl, and Dowex-1X8 and the mixture of HF and HCl with HF concentrations varying from 0.1M to 20M and HCl concentrations from 0.1 to 10M have been measured. The distribution ratios for mixed solutions are presented in form of adsorption contour plots. The connection between the possible composition of the adsorbable complexes and the character of the respective contour plots is discussed.
The behaviour of the elements As, Ba, Cr, Fe, Eu, Hf, La, Mo, Nb, Pa, Re, Sb, Sc, Sn, Ta, Tc, W, and Zr on Dowex-1X8 in 0.1 to 29.5M HF and mixed solutions of HF and NH4F of different concentration combinations varying for both reagents from 0.1 to 10M has been studied. The influence of the ionic form of Dowex-1 on the distribution of elements has also been examined. The distribution ratio for the mixed solutions are given in form of adsorption contour lines.
A systematic study of activation analysis with cyclotron-produced neutrons for (n, 2n), (n, p) and (n, α) reactions is presented.
The limits of detection for elements of atomic number from 6 to 80 are given. The possibilities of optimization of irradiation
conditions by the choice of the most suitable neutron spectrum are discussed. The potential of this fast neutron activation
analysis method is compared with that of 14 MeV neutron activation analysis.
Three different methods for pre-irradiation separation of the tantalum matrix combined with preconcentration of trace elements for NAA were developed. They involve selective extraction of tantalum with diantipyrylmethane, and anion- and cation-exchange from hydrofluoric acid medium. The role of the blank as the limiting factor for limits of detection and accuracy was one of the main aspects of this investigation. A conventional radiochemical NAA based on post-irradiation separation of the matrix radionuclides was also applied. The trace elements considered were Ag, Ba, Ce, Co, Cr, Cu, Eu, Hf, K, La, Mn, Mo, Na, Rb, Re, Sc, W, Y, Zn, Zr. The methods were used for the analysis of tantalum materials of different purity grades. The advantages and disadvantages of each technique are discussed and the achievable limits of detection are given.
A radiochemical neutron activation technique for the detemination of 19 elements in high purity tungsten has been developed. It is based on extraction with diantipyrylmethane (for tantalum and antimony), substoichiometric extraction of molybdophosphate (for phosphorus) and anion-exchange chromatography (other elements) in hydrofluoric acid medium. The results obtained and achievable limits of detection are given. The effects of self-shielding and nuclear interfering reactions are discussed.
Two radiochemical neutron activation analysis techniques capable for the determination of Ag, Au, Cd, Co, Cr, Cs, Cu, Fe,
Hf, Ir, K, Mn, Mo, Na, Ni, Pd, Pt, Rb, Sc, Se, Ta, Th, Sn, W, Zn, and Zr in niobium via medium- and long-lived indicator radionuclides
were developed. They involve two different irradiation and cooling times as well as two different group separation schemes
based on extraction and ion exchange. The achievable limits of detection are between 10−7 g/g and 10−13 g/g. The techniques were applied to analysis of niobium of different purity grades. For a number of elements, the results
of these techniques are compared with those of other techniques.
Chromium, iron and copper were determined in niobium by radiochemical proton activation analysis (PAA). The main steps of
the technique involved the irradiation of the samples with 13 MeV protons, the post-irradiation decontamination of the sample
surface, a two-step separation procedure based on anion exchange from HF and HCl medium, and counting the separated indicator
radionuclides with a well-type NaI detector. For a 5-hr irradiation, limits of detection for chromium, iron, and copper were
0.2, 5.0, and 15 ppb respectively. The results obtained by this technique are compared with data obtained by radiochemical
neutron activation analysis (NAA) and atomic absorption spectrometry (AAS).