HPHT diamonds have been studied for several years for their potential in different applications. In previous studies it has been found that the thermoluminescence (TL) glow curves of "as-grown" HPHT diamonds are non-reproducible. In this work, we study the afterglow (AG), thermoluminescent (TL), and optically stimulated luminescence (OSL) response of commercial samples of synthetic HPHT type-Ib diamond crystals exposed to X-ray irradiation (0.75 mA, 35 kV) at a dose rate of 0.624 Gy/s, after a high gamma ( 60 Co) dose irradiation of 500 kGy followed by a thermal treatment at 1073 K for 1 h in nitrogen atmosphere. Deconvolution of the TL glow curves shows four peaks, located around 379, 509, 561, and 609 K.The crystals exhibit evident AG recorded for 300 s immediately after X-ray irradiation, due to the thermal emptying of the traps responsible for the low-temperature TL peaks (below 400 K). The stimulation of irradiated crystals with 870-nm light, creates pronounced OSL and destroys all TL peaks with the exception of the high-temperature peak at 609 K. The dose responses of the integrated AG, TL, and OSL are linear in the range of 0.6-5 Gy and saturated at higher doses. The reproducibility of AG, TL, and OSL measurements is about 5%. The fading in the first hour of storage in dark conditions at RT of TL signal of HPHT diamond is mainly associated to the emptying of the traps responsible for the 379-K TL peaks.
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 b-radiation (5.4 Gy min À1 ) before and after a stabilization procedure (SP) which includes a high g-dose irradiation (500 kGy) and a thermal treatment (TT) at 1073 K for 1 h in N 2 atmosphere. McKeeve rs 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.
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