INVESTIGATING THE DOSIMETRIC POTENTIALS OF NATURAL MARBLE
C. E. Mokobia
Department of Physics
Delta State University, Abraka, Nigeria
E-mail: mokobia_c@yahoo.com
ABSTRACT
This study examined the thermoluminescence (TL) dosimetric characteristics of natural marble with a view to ascertaining its potential as a TL based retrospective dosimeter. The marble samples from the Basement Complex of South Western Nigeria, were irradiated with a well calibrated 60Co gammacell 220 irradiator. TL measurements were carried out using a ictoreen TL reader (Model 2800M).. The results indicate that the glow curve structure of this the material
is independent of gamma dose except for the height of the main peaks. Its TL output following irradiation is reproducible with a reproducibility index of 0.32 ~ 0.3, the internationally recommended upper limit for most dosimeters. The TL– dose relationship is linear having the equation:
with the TL output being less sensitive than that of TLD-100 the ‘standard’ TL phosphor. Results also indicate that the glow curve is associated with high dose range and its linearity limit of 1.45 kGy is high compared to about 10 Gy of most common TL dosimeters. Furthermore, its fading feature is common to most TL detector materials. The minimum detectable dose for this phosphor is 0.03 kGy. It is therefore concluded that this material has the potential for high radiation dosimetry such as is found in nuclear accidents and radiation processing of food and medical appliances.
Keywords: Marble, Thermoluminescence characters, glow curve, dosimeter