The Application of Low Energy Accelerators to Analysis Problems

Abstract

The work reported here describes the characteristics of low-energy particle accelerators and the way in which these instruments may be used to study analytical problems. Two specific analytical problems, which have been studied using a 500 KV Van de Graaf accelerator, are described. In the first, the stoichiometry of the ferrite MgFe204, formed by sintering MgO and Fe203, was studied using fast neutron activation analysis. Samples of the ferrite were irradiated with 14 MeV neutrons produced in the Van de Graaf by the T(d,n)4 He reaction. The radio-active isotopes 24Na and 56iMn were produced by the reactions 24Mg(n,p)24 and 56Fe(n,p)56Mn. Subsequent y-ray spectrometry enabled the relative quantities of Mg and Fe to be determined, and comparison with similar measurements on unsintered stoichiometric mixes of MgO and Fe203, allowed any relative loss of Mg or Fe during the sintering process to be observed. Samples sintered at 1100°C, 1200°C, and 1400°C all showed a relative loss of about 6% of the iron. The second problem studied was the possible incorporation of F in chromium plating when fluorine salts are incorporated in the plating bath. Samples of the plate were bombarded with protons having various energies up to about 400 KeV. These protons generated the 19F(p,ay)16o reaction at depths within the plate where the protons reached an energy of 340 KeV, at which energy the reaction has a strong resonance. It was observed that all samples had relatively large quantities of F on the surfaces and much lower, but constant, levels in the thickness of the plate. An attempt was made to estimate the amount of F at different depths by comparing the observed y-rays with a standard of CaF2. Possible explanations of these observations are discussed, and further experiments are suggested.