Authors:J. Dale, L. Hulett, S. Pendyala and W. Lyon
In using positrons as analytical tools the experimenter has two quite different options. The first and more obvious is to duplicate electron methods with positrons and see what differences (if any) result. The second is to exploit a unique characteristic of positrons, such as the formation and decay of the positronium atom, to study chemical composition and surface characteristics. Because positrons do not exist freely in our world, they must be obtained from radioactive sources or nuclear interactions. Source intensity has consequently been a limiting factor in experiments that attempt to duplicate electron applications. Some methods of producing and moderating positrons that have been developed here (and elsewhere) are described as well as results from studies using the sources. Surface measurements require less intense sources and yield useful data on materials such as xeolites, silica gels, graphite and alumina. Experimental apparatus, data and interpretation will be discussed.
A survey of the mercury content of the diet in the Glasgow area is described. A higher intake of mercury (60 μg/day/person)
than that expected is found. However, there does not appear to be any concentration of mercury by man. None of the foodstuffs
show any exceptional mercury content. Fish levels are similar to other foods and a preliminary sample of shellfish from the
Clyde estuary, a contaminated area, shown no sign of their having concentrated mercury to any significant degree.
The normal levels of arsenic in human tissue are reported together with the arsenic concentrations found in the investigation
of a large number of industrial exposure incidents. These results are useful for establishing that industrial exposure has
taken place and for confirming arsenic poisoning but they cannot be used realistically to predict that any person or group
will suffer a visible deterioration in health because no correlation between arsenic contamination and symptoms can be made.
Industrial workers who are affected by arsenic exposure are often no more exposed than their co-workers.
Authors:T. Semkow, C. Schwenker, M. Kitto and J. Daly
We describe the operation of a Local Area Network at Nuclear Chemistry Laboratory involved in surveillance of environmental radioactivity. Detailed consideration is given separately to computer and network hardware, radiation instrument interfacing, software, as well as operations. The application of a Local Area Network offers considerable improvements in the laboratory preformance, quality assurance of radioactivity analyses, and data reporting.