Current Search:  Wiedenhöver, Ingo, 1966- (x) » Manousakis, Efstratios (x)

Search results

  • CSV Spreadsheet
(1 - 2 of 2)
Experimental Techniques for Rare Isotope Beam Experiments, and a Study of the Breakout from the Hot CNO-Cycle Through the 19Ne(P,γ)20Na Reaction
Title
Experimental Techniques for Rare Isotope Beam Experiments, and a Study of the Breakout from the Hot CNO-Cycle Through the 19Ne(P,γ)20Na Reaction.
Creator
Belarge, Joseph, Wiedenhöver, Ingo, Plewa, Tomasz, Volya, Alexander, Cottle, Paul D. (Paul Davis), Bonesteel, N. E., Florida State University, College of Arts and Sciences,...
Show moreBelarge, Joseph, Wiedenhöver, Ingo, Plewa, Tomasz, Volya, Alexander, Cottle, Paul D. (Paul Davis), Bonesteel, N. E., Florida State University, College of Arts and Sciences, Department of Physics
Show less
Abstract/Description
The study of exotic nuclei, and their implication for Astrophysics have become a driving force in low-energy nuclear science, nationally recognized by the construction of the Facility for Rare Isotope Beams (FRIB) laboratory. To maximize the potential provided by beams of exotic nuclei, novel detector systems and analysis techniques must be developed, a current focus of the Florida State University (FSU) group. Experimental results from commissioning experiments with the ANASEN and RESONEUT...
Show moreThe study of exotic nuclei, and their implication for Astrophysics have become a driving force in low-energy nuclear science, nationally recognized by the construction of the Facility for Rare Isotope Beams (FRIB) laboratory. To maximize the potential provided by beams of exotic nuclei, novel detector systems and analysis techniques must be developed, a current focus of the Florida State University (FSU) group. Experimental results from commissioning experiments with the ANASEN and RESONEUT detectors at FSU are presented. The neutron deficient ⁹C nucleus was studied through the ⁸B+p resonant elastic scattering reaction. The experiment was conducted during the commissioning of the ANASEN detector in 2012. Due to cryogenics problems, the experiment was stopped prematurely. Through analysis of the partial data set, it was shown that a full analysis could be performed, on complete data sets, for future proton resonance elastic scattering experiments. Results from the ¹⁹O(d,p)²⁰O experiment, also conducted as a part of the commissioning of the ANASEN detector at FSU, will be presented. It was found that heavy ion recoils from the (d,p) reactions were reaching the active zone of the proportional counter, and subsequently producing UV-light radiation that degraded the proportional counter performance. This discovery lead to a re-design of the proportional counter, which is currently being constructed by the ANASEN group at Louisiana State University. An experimental study of low-lying proton resonances in ²⁰Na was performed using the proton transfer ¹⁹Ne(d,n)²⁰Na(p) reaction as part of the commissioning campaign of experiments with the RESONEUT detector. This reaction is comparable to the direct proton capture, ¹⁹Ne(p,ɣ)²⁰Na, which is of astrophysical significance in the breakout from the Hot CNO-cycle. Using protons detected from the decay of ²⁰Na, three resonances were observed, at energies of 0.44 MeV, 0.66 MeV, and 0.82 MeV above the proton threshold. The resonance strengths were determined, and the subsequent ¹⁹Ne(p,ɣ)²⁰Na stellar reaction rate was calculated. A discussion of this reaction rate in the context of the breakout from the Hot CNO-cycle is presented.
Show less
Date Issued
2015
Identifier
FSU_2015fall_Belarge_fsu_0071E_12826
Format
Thesis
WRF Nested Large-Eddy Simulations of Deep Convection during SEAC4RS
Title
WRF Nested Large-Eddy Simulations of Deep Convection during SEAC4RS.
Creator
Heath, Nicholas Kyle, Fuelberg, Henry E., Wiedenhöver, Ingo, Hart, Robert E. (Robert Edward), Bourassa, Mark Allan, Misra, Vasubandhu, Turk, Francis J., Florida State University...
Show moreHeath, Nicholas Kyle, Fuelberg, Henry E., Wiedenhöver, Ingo, Hart, Robert E. (Robert Edward), Bourassa, Mark Allan, Misra, Vasubandhu, Turk, Francis J., Florida State University, College of Arts and Sciences, Department of Earth, Ocean, and Atmospheric Science
Show less
Abstract/Description
Deep convection is an important component of atmospheric circulations that affects many aspects of weather and climate. Therefore, improved understanding and realistic simulations of deep convection are critical to both operational and climate forecasts. Large-eddy simulations (LESs) often are used with observations to enhance understanding of convective processes. This study develops and evaluates a nested-LES method using the Weather Research and Forecasting (WRF) model. Our goal is to...
Show moreDeep convection is an important component of atmospheric circulations that affects many aspects of weather and climate. Therefore, improved understanding and realistic simulations of deep convection are critical to both operational and climate forecasts. Large-eddy simulations (LESs) often are used with observations to enhance understanding of convective processes. This study develops and evaluates a nested-LES method using the Weather Research and Forecasting (WRF) model. Our goal is to evaluate the extent to which the WRF nested-LES approach is useful for studying deep convection during a real-world case. The method was applied on 2 September 2013, a day of continental convection having a robust set of ground and airborne data available for evaluation. A three domain mesoscale WRF simulation is run first. Then, the finest mesoscale output (1.35 km grid length) is used to separately drive nested-LES domains with grid lengths of 450 and 150 m. Results reveal that the nested-LES approach reasonably simulates a broad spectrum of observations, from reflectivity distributions to vertical velocity profiles, during the study period. However, reducing the grid spacing does not necessarily improve results for our case, with the 450 m simulation outperforming the 150 m version. We find that simulated updrafts in the 150 m simulation are too narrow to overcome the negative effects of entrainment, thereby generating convection that is weaker than observed. Increasing the sub-grid mixing length in the 150 m simulation leads to deeper, more realistic convection, but comes at the expense of delaying the onset of the convection. Overall, results show that both the 450 m and 150 m simulations are influenced considerably by the choice of sub-grid mixing length used in the LES turbulence closure. Finally, the simulations and observations are used to study the processes forcing strong midlevel cloud-edge downdrafts that were observed on 2 September. Results suggest that these downdrafts are forced by evaporative cooling due to mixing near cloud edge and by vertical perturbation pressure gradient forces acting to restore mass continuity around neighboring updrafts. We conclude that the WRF nested-LES approach provides an effective method for studying deep convection for our real-world case. The method can be used to provide insight into physical processes that are important to understanding observations. The WRF nested-LES approach could be adapted for other case studies in which high-resolution observations are available for validation.
Show less
Date Issued
2015
Identifier
FSU_2015fall_Heath_fsu_0071E_12917
Format
Thesis