The core-logger has been designed for the high-resolution radiometric analysis of soil
cores using multiple detectors. This device allows for the automation of the
measuring process and eliminates the need to dissect the cores. The design is aimed
at measuring soil-cores with a 10cm radius and a length of 1m and allows for up to 4
detectors to be mounted on the measuring platform. Currently a combination of
Bismuth-German.te (BGO) and C.esiwn-Iodide (CsI) detectors are used.
The core logger required a good spatial resolution of - 1 cm. This has been difficult to
obtain and has required extensive investigation. The shielding configurations were
varied and the effect of background radiation was looked at in detail to determine an
optimal construction. A secondary objective has been the complete measurement of a
single core in 24 hours. This has also been difficult to achieve because the low
activity of natural radiation in the core samples needs longer measuring times. The
BGO detectors were used as a more efficient detector (than, e.g. CsI) which helped to
reduce the required measuring time.
Measured spectra have been analysed to determine the activity concentrations of the
specific radionuclides of interest: 232Th, 238U, 40K and 137Cs. These activity profiles of
the measured cores provide information that can then be used to radiometrically
fingerprint the sample to determine soil characteristics such as grain size and mineral
content. However, because the actual resolution of the system ( ~3cm) is greater than
the typical core slice (~ 2cm), the radiometric information in a specific core-slice
contains contributions from its adjacent slices. This folding or convolution of the
measured spectra can be undone using a deconvolution method. which was examined
and commented on. / Thesis (M.Sc.)-University of Natal, Durban, 2001.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/5467 |
| Date | January 2001 |
| Creators | Pitout, Richard. |
| Contributors | Alport, Michael J. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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