TL Analyses on Filter Test Results of Synthesized Un-Doped and Doped Zn2SiO4 Phosphors for Dosimetry Purpose


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Portakal Z. G. , Akça S. , Oğlakçı M., Kaynar Ü. H. , Ayvacıklı M., Yüksel M. , ...More

2. ULUSLARARASI GAP MATEMATİK - MÜHENDİSLİK - FEN VE SAĞLIK BİLİMLERİ KONGRESİ, Adıyaman, Turkey, 21 - 23 June 2019, pp.37-45

  • Publication Type: Conference Paper / Full Text
  • City: Adıyaman
  • Country: Turkey
  • Page Numbers: pp.37-45

Abstract

Zinc silicate (Zn2SiO4) is defined as a suitable host-matrix having excellent luminescence properties in red, green and blue spectral regions and also having high chemical stability.

The aim of this study was to investigate the production and use of new dosimetric materials with the most ideal properties by adding different Rare Earth Element (REE) to Zn2SiO4 component using the gel-combustion method. The dosimetric properties of un-doped, Sm3+ doped and Ce3+ doped Zn2SiO4 phosphors were tested by using thermally stimulated luminescence (TL) method. The preliminary part of the study included “filter test” to define optimal measurement parameters. All TL measurements were performed using an automated Lexsyg Smart TL/OSL reader system having different filter combinations (wideband, 365, 410, and 565 nm). The reader also has an internal 90Sr/90Y source with a dose rate of 0.11 Gys-1. The glow curve readouts were performed at a linear heating rate (HR) of 5 oCs-1 from room temperature (RT) to 450 oC with 10 Gy dose.

Results of TL glow curves of each sample showed that TL intensity yielded successful results when using IRSL wideband blue and IRSL 565 nm filters. Thus, pre-heat (PH) tests were performed to analyze dosimetric TL peak(s) for each sample and detection filters used. A single dosimetric peak was obtained for Zn2SiO4 (225 oC with wideband blue and 290 oC with 565 nm) and Zn2SiO4:2.0%Sm (240 oC with wideband and 282 oC with 565 nm) phosphors when using both filters. However, visible peak maxima consist of the nested peaks in Zn2SiO4:2.0%Ce phosphor when both filters were used. In general, better reusability values of Sm3+ and Ce3+ doped Zn2SiO4 phosphors were obtained when both filters were used within ± 3%. Fading results represented the tunneling effect in some samples related to the fading time using especially IRSL 565 nm filter. The least change was obtained when a 565nm filter was used. Zn2SiO4:2.0%Sm sample showed unexpected results called “Anomalous Fading” effect when the TL readout was repeated after a week.