Mechanism of thermoluminescence in high energy carbon ion irradiated Tb3+ doped Al2O3 phosphor for carbon ion beam dosimetry

Abstract

Thermoluminescence (TL) properties of 80 MeV C6+ ion irradiated pure and Tb3+ doped Al2O3 phosphors are reported. Undoped and Tb3+ doped Al2O3 phosphors are synthesized by solution combustion method. Crystalline phase is analyzed by x-ray diffraction (XRD) and average crystallite size is found to be ~64 nm. XRD pattern of Al2O3:Tb3+ (0.05 mol%) is analyzed by Rietveld refinement using the FULLPROF program. TL glow curves of C6+ ion irradiated pure and Tb3+ doped Al2O3 phosphors are recorded for low fluence (5.06 × 106 to 2.05 × 108 ions cm−2) and high fluence (1 × 1010 to 5 × 1012 ions cm−2). TL glow curves of C6+ ion irradiated pure Al2O3 shows prominent peaks at ~466 K and ~623 K with shoulder at ~569 K. These glow peaks are ascribed to Cr3+and Mn4+ emissions. The effect of Tb3+ concentration on TL is investigated and optimum Tb3+ concentration is found to be 0.05 mol%. These Tb3+ doped TL glow curves exhibit a new well resolved prominent peak at 569 K with small humps at 466 K and 623 K. This new TL glow peak is due to Tb3+ characteristic emission. Further, linearity, kinetic parameters, repeatability and fading effect of pure and Tb3+ doped Al2O3 phosphors are studied and they exhibit appropriate properties for carbon beam dosimetry in radiation therapy.