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  • Author or Editor: L. Alaerts x
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Abstract  

A comparison has been made between flux density distributions from massive and ring-shaped cylindrical isotopic neutron sources. A considerable gain in direct fast neutron flux is obtained for the latter geometry as well as a neat separation of fast and thermal flux density maxima along the axis of the source. Applications of these favourable properties are discussed.

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Abstract  

A non-destructive method has been developed for the precise and accurate determination of Sn in cassiterite ores. Irradiation is performed by means of a 6.6 Ci227Ac−BE isotopic neutron source with a total neutron output of 108 n·sec−1. Samples are pellets pressed from a mixture of cassiterite powder and wax as a binding material. With a 4 hrs analysis time and a relative precision of 0.45%, the new method is faster and at least as precise as any existing destructive chemical method. The accuracy is proved to be better than that of the commonly used iodimetric titration method.

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Abstract  

A method has been developed to routinely analyse managanese ores and ferro-manganese, by neutron activation making use of a cylindrical 1 Ci226Ra−Be source. A description of the source, the moderator and the pneumatic irradiation facility is given. The irradiation position has been optimized for minimum flux gradients and maximum reproducibility. Samples and standards consist of pellets pressed from a mixture of powdered material and graphite weighing approximately 5 g. Samples and standards alternatively go through a sequence of 20 min irradiation, 20 min decay, and 20 min counting. Pyrolusites containing from 30 to 55% Mn and ferro-manganese containing approximately 80% Mn have been analysed with a precision of 0.1% absolute.

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