Optimal conditions of X-ray irradiation for accurate equivalent dose determination

Luminescence excited by a small X-ray generator (Varian VF-50J) instead of the usual 90Sr-90Y beta source was measured following optical stimulation. The optimal X-ray irradiation conditions have been assessed, including the irradiation dose rate and the thickness of Al-absorber, in the equivalent dose determination when a luminescence dating process is simulated with laboratory dosed quartz samples. The equivalent doses were found to greatly depend on both the thickness of Al-absorber and the X-ray dose rate. We suggest that the optimal X-ray irradiation conditions for accurate luminescence dating work can be obtained by applying the following: (i) use of an Al-absorber with a thickness of 200 μm and (ii) X-ray dose rates of 0.38 Gy/min to 2.9 Gy/min.