ABSTRACT
Characteristics of continuous wave optically stimulated luminescence (CW-OSL) and linear modulation OSL (LM-OSL) from three different types of cowrie shells are presented. Irradiated samples were optically stimulated at 72 mW/cm2 for CW-OSL and linearly ramped from zero to 72 mW/cm2 to obtain LM-OSL. The measured CW-OSL and LM-OSL curves of the shells are each determined to consist of three components namely fast, medium and slow components. The fast, medium and slow LM-OSL components peak at 17.0 ± 0.8, 45.0 ± 1.8 and 140.8 ± 6.7 s respectively for all samples. In addition, peak positions are independent of dose. The photoionization cross-sections of the OSL traps for the three components estimated from CW-OSL are similar to those determined using LM-OSL. The OSL of the three components increases linearly with dose. The coefficient of variation of responses from repeated measurements of same aliquot lies below 2.3%. The shells are thus potential materials for retrospective dosimetry.
