Thermoluminescence studies on HPHT diamond crystals exposed to β-irradiation

A study of the thermoluminescent response of commercial synthetic high pressure high temperature (HPHT) type-Ib diamond crystals is reported. In previous works, it was found that the thermoluminescence (TL) glow curves of HPHT diamonds are non-reproducible. In this work, we compare the TL of samples irradiated with β-radiation (5.4 Gy min⁻¹) before and after a stabilization procedure (SP) which includes a high γ-dose irradiation (500 kGy) and a thermal treatment (TT) at 1073 K for 1 h in N₂ atmosphere. McKeeveŕs method and Kitis general kinetics order were used, identifying four peaks around 389, 465, 507, and 567 K before the SP which shifted to lower temperatures around 373, 455, 489, 527 K after the SP and the rise of a new TL peak around 620 K. Before the SP both the TL and afterglow (AG) signals presented irregular dosimetric behavior, especially the low temperature TL peaks (373 and 455 K). The uncertainty associated to TL reproducibility was of 12%. After the SP cycle, the TL and AG showed an enhancement in their linear dosimetric response between 0.09 and 1 Gy, reaching saturation around 2 Gy. The TL reproducibility was significantly improved with deviations around 3%, and a better behavior of TL fading was observed.