Person: AKYÜREK, TAYFUN
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AKYÜREK
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TAYFUN
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Publication Open Access Simultaneous experimental evaluation of pulse shape and deadtime phenomenon of GM detector(NATURE RESEARCH, 2021-12) AKYÜREK, TAYFUN; Almutairi, Bader; Alam, Syed; Goodwin, Cameron S.; Usman, Shoaib; Akyurek, TayfunAnalysis of several pulse shape properties generated by a Geiger Mueller (GM) detector and its dependence on applied voltage was performed. The two-source method was utilized to measure deadtime while simultaneously capturing pulse shape parameters on an oscilloscope. A wide range of operating voltages (600-1200 V) beyond the recommended operating voltage of 900 V was investigated using three radioactive sources (Tl-204, Cs-137, Na-22). This study investigates the relationship between operating voltage, pulse shape properties, and deadtime of the detector. Based on the data, it is found that deadtime decreases with increasing voltage from 600 to 650 V. At these low voltages (600-650 V), the collection time was long, allowing sufficient time for some recombination to take place. Increasing the voltage in this range decreased the collection time, and hence deadtime decreased. It is also observed that rise and fall time were at their highest at these applied voltages. Increasing the voltage further would result in gas multiplication, where deadtime and pulse width are observed to be increasing. After reaching the maximum point of deadtime (similar to 250 mu s at similar to 700 V), deadtime started to exponentially decrease until a plateau was reached. In this region, it is observed that detector deadtime and operating voltage show a strong correlation with positive pulse width, rise and fall time, cycle mean, and area. Therefore, this study confirms a correlation between detector deadtime, operating voltage, and pulse shape properties. The results will validate our hypothesis that deadtime phenomena at different operating voltages are phenomenologically different.Publication Open Access Delayed fast neutron as an indicator of burn-up for nuclear fuel elements(KOREAN NUCLEAR SOC, 2021-10) AKYÜREK, TAYFUN; Akyurek, T.; Shoaib, S. B.; Usman, S.Feasibility study of burn-up analysis and monitoring using delayed fast neutrons was investigated at Missouri University of Science and Technology Reactor (MSTR). Burnt and fresh fuel elements were used to collect delayed fast neutron data for different power levels. Total reactivity varied depending on the burn-up rate of fuel elements for each core configuration. The regulating rod worth was 2.07E-04 Dk/k/in and 1.95E-04 Dk/k/in for T121 and T122 core configurations at 11 inch, respectively. Delayed fast neutron spectrum of F1 (burnt) and F16 (fresh) fuel elements were analyzed further, and a strong correlation was observed between delayed fast neutron emission and burn-up. According to the analyzed peaks in burnt and fresh fuels, reactor power dependency was observed and it was determined that delayed neutron provided more reliable results at reactor powers of 50 kW and above. (c) 2021 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Publication Open Access A new dead-time determination method for gamma-ray detectors using attenuation law(KOREAN NUCLEAR SOC, 2021-12) AKYÜREK, TAYFUN; Akyurek, T.This study presents a new dead-time measurement method using the gamma attenuation law and generalized dead-time models for nuclear gamma-ray detectors. The dead-time of the Nal(TI) detection system was obtained to validate the new dead-time determination method using very thin lead and polyethylene absorbers. Non-paralyzing dead-time was found to be 8.39 mu s, and paralyzing dead-time was found to be 8.35 mu s using lead absorber for Nal(TI) scintillator detection system. These dead-time values are consistent with the previously reported dead-time values for scintillator detection systems. The gamma build-up factor's contribution to the dead-time was neglected because a very thin material was used. (C) 2021 Korean Nuclear Society, Published by Elsevier Korea LLC.Publication Metadata only Characterization of different reactor parameters of TRIGA Mark II, PWR and VVER under various conditions(2022-06-30) AKYÜREK, TAYFUN; AKYÜREK T., AÇIKGÖZ D.Publication Open Access Experimental evaluation of the deadtime phenomenon for GM detector: deadtime dependence on operating voltages(NATURE RESEARCH, 2020-12) AKYÜREK, TAYFUN; Almutairi, Bader; Alam, Syed; Akyurek, Tayfun; Goodwin, Cameron S.; Usman, ShoaibA detailed analysis of Geiger Mueller counter deadtime dependence on operating voltage is presented in the manuscript using four pairs of radiation sources. Based on two-source method, detector deadtime is calculated for a wide range of operating voltages which revealed a peculiar relationship between the operating voltage and the detector deadtime. In the low voltage range, a distinct drop in deadtime was observed where deadtime reached a value as low as a few microseconds (22 mu s for Tl-204, 26 mu s for Cs-137, 9 mu s for Na-22). This sharp drop in the deadtime is possibly due to reduced recombination with increasing voltage. After the lowest point, the deadtime generally increased rapidly to reach a maximum (292 mu s for Tl-204, 277 mu s for Cs-137, 258 mu s for Na-22). This rapid increase in the deadtime is mainly due to the on-set of charge multiplication. After the maximum deadtime values, there was an exponential decrease in the deadtime reaching an asymptotic low where the manufacturer recommended voltage for operation falls. This pattern of deadtime voltage dependence was repeated for all sources tested with the exception of Mn-54. Low count rates leading to a negative deadtime suggested poor statistical nature of the data collected for Mn-54 and the data while being presented here is not used for any inference.