Silver doped lithium tetraborate (Li2B4O7) single crystals as efficient dosimeter material with sub-micro-Gy sensitivity

• Published in: Journal of luminescence Vol. 157; pp. 333 - 337
• Main Authors: Patra, G.D., Singh, S.G., Singh, A.K., Tyagi, M., Desai, D.G., Tiwari, B., Sen, S., Gadkari, S.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-01-2015
• Subjects: Czochralski crystal pulling; Dosimetry; Photoluminescence; Single crystal; Thermally stimulated luminescence; Thermally stimulated luminescence; Czochralski crystal pulling; Dosimetry; Single crystal; Photoluminescence
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2014.09.017

Single crystals of Li2B4O7 (LTB) with varying Ag content were grown using the Czochralski technique and studied for their optical absorption, photo-luminescence (PL) and thermally stimulated luminescence (TSL) properties. The optimum Ag concentration in the LTB was found to be about 500ppm for the best TSL properties. A TSL readout set-up has been described that uses a solar blind photo-multiplier tube (PMT) to match the emission from Ag which is in the UV region (peak at 270nm). This has significantly improved the performance of the TSL set-up by lowering dark counts and enhancing the signal due to a better matching between the emission from Ag ions and PMT response. In addition, the use of the solar blind PMT also minimized the thermal noise generated from heating of sample in the TSL set-up. Radiation doses lower than 5μGy could be measured using this set-up with small LTB:Ag crystal samples (100mg). The lower detection limit has been estimated to be 500nGy.
•Photoluminescence and thermally stimulated luminescence studies on Ag doped Li2B4O7 single crystal.•Determination of optimum Ag concentration (in melt) in Li2B4O7 to prepare sensitive dosimetric material.•Design of a suitable TSL read-out system to realize full potential of Ag doped Li2B4O7 crystal.•Experimentally measured dose of 3μGy.