Carlo Vandecasteele

Standardization in charged particle activation analysis

Standardization methods in activation analysis with charged particles are studied critically. Several approximate standardization methods that do not require knowledge of the excitation function are compared with the “numerical integration method” using excitation function data from the literature. It is shown that these methods yield accurate results if the threshold energy of the considered reaction is high and if sample and standard have a comparable Z value. A method that gives a rapid estimate of the maximum possible error is also presented. It is shown that for the “numerical integration method” the accuracy of the excitation function data has only a small influence on the overall accuracy. The influence of the accuracy of stopping power data and of possible deviations from Braggs rule for light element standards is also considered.

Determination of Bromine in Human Serum by Inductively Coupled Plasma-Mass Spectrometry

Abstract The determination of bromine in human serum by inductively coupled plasma-mass spectrometry (ICP-MS) is discussed. Sample preparation was kept as limited as possible: serum samples were only diluted with nitric acid (five- or ten-fold). Indium was added as internal standard. In order to avoid overlap of 40Ar 40Ar with

Determination of cadmium, thallium and lead in environmental samples by proton activation analysis

Cadmium, thallium and lead are determined in environmental samples using the111,112,113Cd(p,xn)111In,203Tl(p,3n)201Pb and206,207,208Pb(p,xn)206Bi reactions.111In.201Pb and206Bi are chemically separated by anion exchange and anodic deposition of lead(IV). oxide. Detection limits are 6, 44 and 25 ng/g for cadmium, thallium and lead, respectively. The results obtained for certified reference materials are in good agreement with the certified values.

Sensitivities and interferences in activation-analysis with cyclotron-produced fast-neutrons

Fast neutrons are produced by irradiation of a thick beryllium target with deuterons from a cyclotron. The spatial neutron flux distribution was studied. Ge(Li) gamma-ray spectrometry was used to measure the radionuclides produced. Detection limits are tabulated along with the nuclear interferences.

Cyclotron production of13N-labelled ammonia for medical use

A new method for the production of13N-labelled ammonia is described.

Activation analysis with cyclotron-produced fast neutrons. Application to instrumental multi-element analysis and to the radiochemical determination of fluorine

Fast neutrons produced by irradiation of a thick beryllium target with 20–50 MeV deuterons are used for activation analysis. The spatial neutron flux distribution around the target is measured. A rotating sample holder is used for the simultaneous irradiation of samples and standards. Instrumental analysis can be applied for a number of elements. As an example, results for calcium and strontium in some reference materials are given. The19F(n, 2n)18F reaction is used for the radiochemical determination of fluorine in rocks with a fluorine concentration ranging from 9 to 5400 μg·g−1

Determination of light elements in metals and semiconductors by charged particle activation analysis

The determination of boron, carbon, nitrogen and oxygen in metals and semiconductors by charged particle activation analysis (CPAA) is reviewed. It is shown that CPAA is a sensitive and accurate method suitable for the analysis of reference materials.

The determination of boron in rocks by deuteron activation analysis

The determination of boron in rocks by charged particle activation using the10B(d, n)11C reaction is studied. A sample holder that allows reproducible irradiation of powdered samples is developed.11C is separated as11CO2. For boron concentrations between 2.35 and 25.2 μg·g−1, the standard deviations ranges from 7.1 to 22.8%. The results for USGS reference silicate rocks and Moroccan phosphate rock are compared to those obtained by other techniques.

Thermal behaviour of rock and environmental samples during proton irradiation

The temperature in powdered rock and environmental samples irradiated with 23 MeV protons was measured. Under helium (3–9·105 Pa) the obtained temperature is considerably lower than under vacuum. Irradiation under helium at a sufficiently low beam intensity allows to avoid systematic errors that may occur in charged particle activation analysis due to volatilization of matrix components.

The determination of trace oxygen in lead by helium-3 and helium-4 activation analysis

The determination of oxygen in lead by3He and4He activation analysis was studied. Both methods were applied to the same material containing 0.9 μg·g−1 of oxygen. The18F formed from oxygen was separated from matrix activities by extraction of Po with N-benzoyl-N-fenylhydroxylamine, followed by distillation of fluorosilicic acid and precipitation of lead fluorochloride (4He activation) or by distillation followed by precipitation (3He activation). The yield of the separation, which amounted on the average to 68%, was determined via the19F(n,4He)16N reaction. The coefficients of variation were 21 and 45% for4He and3He activation analysis, respectively, thus indicating a less homogeneous distribution of the oxygen. Nuclear interferences of sodium and fluorine were shown to be negligible.