Dosimetry characteristics of thermoluminescent Li2B4O7:Cu phosphor

Preliminary investigations on the radiation dosimetry characteristics of Li2B4O7:Cu TLD phosphor are described. The major TL peak in this phosphor occurs at 2300C and its TL sensitivity to gamma radiation is two to three times higher than that of LiF TLD-100. The gamma dose Vs TL response of this peak is linear (within +- 20%) in the dose range 0.3 mGy-3x102Gy above which saturation sets in. Its TL response for 30 keV X-rays is about 20% lower than that for 60Coγ-rays. On annealing at 3000C, the phosphor gets slightly discoloured (brownish). This results in the reduction of the TL sensitivity by about 20 - 25%. The phosphor does not exhibit either sensitization or damage even after a gamma dose of 103 Gy. The TL emission spectrum has a broad peak at 360 nm. The intrinsic TL sensitivity of virgin Li2B4O7:Cu to 253.7 nm UV radiation is nearly 50 times higher than that of CaSO4:Dy. The post-irradiation fading in Li2B4O7:Cu at ambient temperature and humidity conditions is, however, less than 10% in 17 days. These characteristics indicate that Li2B4O7:Cu is a promising phosphor for ionizing as well as UV radiation dosimetry. (author)