Characterization of natural soda ash for dosimetry using thermoluminescence technique

Soda ash, due to its various use for industrial applications, is a phosphor likely to be found in the vicinities of radiation facilities where retrospective dosimetry may be required in the unlikely events of radiation accidents/incidents. The ash is therefore a potential material for retrospective dosimetry using luminescence techniques. In this report, the thermoluminescence characteristics of soda ash from Suan pan, Botswana are presented. The thermoluminescence glow curve of the soda ash consists three peaks near 79, 175 and 329 °C with a shoulder around 221 °C. The peak intensities of the peaks and the whole glow curve integrated intensity are linear with dose. T_m-T_stop analysis reveals soda ash contains four peaks near 82, 211, 235 and 335 °C. The four peaks are affected by thermal quenching with activation energy of thermal quenching 0.64 eV, 0.29 eV, 0.66 eV and 0.29 eV respectively. The intensities of the peaks decrease with optical stimulation. The minimum dose the phosphor can measure is evaluated to be 0.34 Gy. The thermoluminescence from soda ash is suitable for dosimetry, especially for high dose measurement. The peak near 335 °C with mean lifetime greater than 250 years is the most suitable for dosimetry. The phosphor may be able to produce phototransfer thermoluminescence.