Description: Publication date: January 2018 Source: Radiation Measurements, Volume 108

Description: Publication date: Available online 16 December 2017 Source: Radiation Measurements Author(s): O. Antohi-Trandafir, A. Timar-Gabor, A. Vulpoi, R. Bălc, J. Longman, D. Veres, S. Simon Muscovite is a mineral commonly found along quartz in sediments, where the latter is the mineral of choice in numerous optically stimulated luminescence (OSL) dating studies. Since muscovite cannot be efficiently eliminated following standard laboratory treatments, it is important to assess its luminescence properties. This study is focused on the investigation of muscovite hand-picked from a quartz sample extracted from loess and of museum specimens of muscovite in order to evaluate their potential implication in the OSL dating of quartz samples contaminated with muscovite grains. The obtained results show that generally applicable luminescence characteristics cannot be described for muscovite. In terms of the thermoluminescence (TL) response, all samples investigated display the same wide peak at 200 °C. The blue light and infrared (IR) sensitivities differ between the samples: 3 out of 5 samples present no or negligible level of OSL and IRSL response, while the other 2 samples are characterised by both blue light (2000–3400 counts in 0.31 s of stimulation for 10 mg of muscovite after irradiation with a dose of 136 Gy) and IR sensitivity (265–320 counts in 0.31 s of stimulation for 10 mg of muscovite after irradiation with a dose of 136 Gy). Based on the samples analysed in this study, aliquots of quartz contaminated with optically (blue light) sensitive muscovite would also be IR sensitive. Hence, potentially problematic aliquots can be identified via the IRSL purity test usually used in the OSL dating of quartz samples for detection of feldspar contamination. The impact of muscovite on dose determination for quartz was also tested and it was concluded that at least in the case of bright quartz, muscovite minerals do not influence the OSL measurements.

Description: Publication date: Available online 15 December 2017 Source: Radiation Measurements Author(s): Alexander Romanyukha, Matthew D. Grypp, François Trompier, Alan K. Thompson, Ronaldo Minniti, Jacques Debroas, Anthony S. Williams Results of a comprehensive study of the TLD-700H/600H (Harshaw 8840/8841) dosimetry system performance for an extended issue period are presented and discussed. The results provide a technical justification to use the current dosimetry system issues periods up to almost 600 days, far beyond the current 95-day issue period used at the Naval Dosimetry Center (NDC). Extending (or reducing) the issue period has a statistically significant effect on the uncertainty of the dose equivalent values measured within the dosimetry system. In order to accommodate the use of various issue periods for the dosimetry system, the lower limit of detection (LLD) linear model is proposed. A possible limitation of this model (dose fading) is discussed. The factors responsible for both time independent and dependent LLD components are identified. The thermoluminescent residual signal and dosimetry system calibration are responsible for the time-independent LLD component; whereas the factors for time-dependent LLD component are dose fading, radiation background and its standard deviation. Simple formulae for photon and neutron LLDs at variable dosimeter issue periods are proposed. As a result of the experimental study conducted, multiple LLD components were numerically evaluated for the four-element TLD-700H/600H dosimetry system at different issue periods. Implementation of these formulae in the Dose Program may provide a more accurate LLD estimation for each reported dose equivalent at any technically justified dosimeter issue period.

Description: Publication date: Available online 14 December 2017 Source: Radiation Measurements Author(s): He Feng, Jianyu Chen, Zhijun Zhang, Yong Wang, Zhan Xu, Zhao Jingtai, Rihua Mao A single crystal of Gd 1.9 Y 0.1 SiO 5 :0.5%Ce (GYSO:Ce) was grown using the Czochralski method and its structure, photoluminescence, and scintillation properties were analyzed. Based on Rietveld structure refinement, we found that mixing with Y5at% changed the host structure very little. Two typical types of cerium emission, i.e., Ce1 and Ce2, were confirmed based on the photoluminescence excitation and emission spectra at 77 K. The energy transfer of Gd 6 P J →Ce1 probably explains the slow component in the photoluminescence and scintillation processes. The light yield of the GYSO:Ce sample was determined as 11200 ph/MeV and the energy resolution was 8.6%. The afterglow intensity of GYSO:Ce was relatively low.

Description: Publication date: Available online 14 December 2017 Source: Radiation Measurements Author(s): Seiichi Yamamoto, Katsuhiko Kato, Hiroshi Kameyama, Shinji Abe Ra-223 has recently been introduced in alpha-targeting radionuclide therapy. According to the decay scheme of Ra-223, beta particles with higher energy than the Cerenkov-light threshold are emitted. In addition, there are reports that the alpha particles themselves emit luminescence in water and air. However, measured optical imaging results from Ra-223 have not yet been reported. Therefore, we conducted optical imaging of an Ra-223 solution and compared it with that of an F-18 solution. Ra-223 and F-18 solutions contained in transparent glass vials were imaged using a high-sensitivity CCD camera. We could obtain an image of the Ra-223 solution with radioactivity of 0.72 MBq in an acquisition time of less than 10 s. At the same level of radioactivity, the intensity of the optical signal in the solution part of the vial of Ra-223 was 21 times higher than that of F-18. Furthermore, in the air part of the vials, Ra-223 had higher luminescence than that of F-18. The light spectra for Ra-223 and F-18 solutions were similar, but those in the vials' air parts were different. The optical signals in the solution part of both Ra-223 and F-18 are attributed to Cerenkov light, while that in the air part of Ra-223 is attributed to the scintillation of N 2 gas in air. No obvious luminescence of water by the alpha particles was observed. We concluded that optical imaging of the Ra-223 solution was possible, and this solution's light intensity was much higher than that of the F-18 solution and thus easier to detect. Therefore, Ra-223 is a promising radionuclide for optical imaging in distribution measurements.

Description: Publication date: Available online 2 December 2017 Source: Radiation Measurements Author(s): Owen M. Williams, Nigel A. Spooner The well-known 160 °C and 220 °C intermediate temperature bands in quartz thermoluminescence are attributed to the same defect reaction pair proposed previously to explain the 110 °C predose band. In particular, the trend towards longer spectral wavelengths as the glow proceeds across the 110 °C, 160 °C and 220 °C bands is shown to be consistent with the known energy levels of the [AlO 4 − /h + ] 0 substitutional defect.

Description: Publication date: November 2017 Source: Radiation Measurements, Volume 106

Description: Publication date: November 2017 Source: Radiation Measurements, Volume 106

Description: Publication date: November 2017 Source: Radiation Measurements, Volume 106 Author(s): Clemens Woda, Markus Figel, Dieter Regulla

Description: Publication date: December 2017 Source: Radiation Measurements, Volume 107