ABSTRACT
Trap stability is essential in luminescence dating and thermochronometry. Trap depth and frequency factors determining the stability of the fast component of optically stimulated luminescence (OSL) in quartz, which is the most important in dating, have yet to be uniquely determined, especially for samples with an OSL signal not dominated by this component. One can determine them in OSL thermal depletion curve (OTDC) experiments. The separation of the fast OSL signal undisturbed by other OSL components is vital for obtaining accurate parameters for the traps of interest. This work presents a method of simultaneous thermal and optical stimulation using red light (620 nm) to separate the fast OSL component (the thermally modulated OSL method-TM-OSL). The OTDC experiment with the TM-OSL stimulation was used for the trap parameter determination on a variety of quartz samples, leading us to report for the first time, the trap parameters for the fast OSL component analytically separated in quartz from rock samples. The results obtained for these samples with the fast component of low intensity are consistent with those with an intensive fast OSL component. Results of OTDC measurements for all investigated quartz samples were tested for a wide range of irradiation doses.
ABSTRACT
Sodium chloride (NaCl) is a phosphor with potential significance in retrospective dosimetry and geological dating. NaCl has been extensively studied for practical use in OSL dosimetry, however, the exact mechanism of the OSL emission is not well explained. This work attempts to extend the information on NaCl luminescent properties by establishing the occurrence of very deep traps in NaCl using the thermally assisted OSL (TA - OSL) method. The studied material was sodium chloride in different forms: halite minerals from Klodawa salt mine in Poland and NaCl in chemically pure form. The isothermal TA - OSL signal was measured at various temperatures between 25⯰C and 280⯰C after a prior irradiation and TL erasing of shallow and main traps. The appearance of a strong TA - OSL signal indicates the occurrence of very deep traps in all forms of investigated salt. The temperature dependence of TA - OSL was determined and the activation energy for thermal assistance corresponding to deep traps in NaCl was estimated. For selected temperatures of TA - OSL readout (200⯰C and 280⯰C) the dose response was examined in wide dose range (1-1000â¯Gy). Sublinearity was found in different dose range depending on the type of samples.
ABSTRACT
INTRODUCTION: Various modifications of standard endovascular aortic aneurysm repair (EVAR) have been developed to solve the problem of difficult neck anatomy. AIM: The authors propose the implantation of a predeployed extension cuff (kilt) using on-shelf Endurant II elements. In a vast majority of cases, the proposed method provides a solution for the hostile neck problem using standard Endurant II elements available in all centers performing subrenal EVAR procedures. MATERIAL AND METHODS: The early outcomes of kilt implantation were evaluated in 11 patients (three with ruptured abdominal aortic aneurysms, one symptomatic) in 2 vascular centers in Silesia (Poland). All patients presented with hostile neck anatomy defined as neck length < 10 mm, diameter > 28 mm, angulation > 60°, mural thrombus or calcium > 2 mm in thickness or > 180° circumference. RESULTS: No intraoperative type I endoleak or device migration was observed. Two perioperative deaths occurred in patients in a severe condition with ruptured aneurysms. One case of type III endoleak was managed by the implantation of an additional iliac extension with complete endoleak sealing. CONCLUSIONS: The proposed method seems to be effective in early endoleak prevention in patients with hostile neck anatomy undergoing EVAR procedures; however, studies with long-term follow-up are needed.
