Browsing by Subject "resonance"
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Item One proton, two proton, and alpha emission from 14o+alpha resonance interactions(2009-05-15) Fu, ChangboIn this dissertation, proton, two proton, and emission from the 14O + a interactions were studied with the modified thick target inverse kinematics approach. The radioactive beam was obtained by using resonances in the 14N(p, n)14O reaction. The 14O was > 99% pure. By using a beam analysis system, the contaminant-tobeam ratio was suppressed further to the 10?4 level. This makes the 14O beam at TAMU one of the best available. For the 14O(a, 2p) interaction, it was found that the resonance excited states in 18Ne are populated, and most of them decay sequentially to the ground state of 16O, i.e. 18Ne* ! 17F* + p ! 16O + p + p. Two proton events corresponding to the excited state of 18Ne*(8.45MeV), were found to have strong 2p correlation, which is the fingerprint of 2He-decay. Several models were used to explain this decay process, and evidence suggests that this state decays by 2He-emission. By measuring the Time-Of-Flight for protons through the thick target, the location of 14O(, p) reactions occurring at different places in the helium gas target were identified. With this information, we were able to measure a spectrum of protons corresponding to the population of 17F particle stable states in the 14O(a, p)17F reaction. This method provides a new way to measure astrophysically important reactions which involve radioactive nuclei and a particles. By analyzing elastic scattering of 14O and 14C on 4He, a-cluster states in 18Ne* and 18O* were found. Some a-cluster states in 18Ne* were found for the first time.Item Optical control of nuclear resonant absorption: theory and experiment(Texas A&M University, 2004-09-30) Kolesov, Roman L.Modification of nuclear resonant absorption by means of laser radiation is analyzed both theoretically and experimentally. Theoretical analysis is done on the basis of four-level model of atom. This model includes both electronic and nuclear excitations. It is predicted that under coherent laser driving nuclear resonant Mossbauer absorption can be significantly modified, e.g. new Mossbauer resonances can appear, some of the existing resonances can vanish, both can be Rabi-split, broadened by laser action. In addition, it is predicted that Mossbauer absorption can be completely suppressed due to coherent population trapping. Experimental observation of laser-induced transformations of Mossbauer spectra of 57Fe2+ : MgO is accomplished. New Mossbauer lines appear with laser driving while the existing are broadened. Possible explanations of the observed changes in 57Fe2+ : MgO Mossbauer spectra are population of higher-lying electronic states of iron ion and significant modification of electronic relaxation processes due to modified Jahn-Teller interaction.Item Spin-orbit coupling in the solar system(2009-05) Marsh, Jasmina Pozderac; Llave, Rafael de la; Gonzalez, Oscar, 1968-The existence of the exact commensurability between the periods of rotation and revolution of a satellite orbiting a planet is not a rare phenomenon in the Solar system. In fact, there are several examples of such resonances with the Earth-Moon system being the most familiar example of a 1:1 (synchronous) resonance. In this report, I will discuss the questions of stability of five resonant systems (Moon – Earth, Enceladus - Saturn, Dione - Saturn, Rhea – Saturn, and Mercury – Sun (the only non – synchronous resonance among the evolved spin – orbit resonances in the Solar system). Several authors have investigated the stability of spin-orbit resonances, and, in this report, I will concentrate on the two most recent investigations.Item Tubulin in vitro, in vivo and in silico(Texas A&M University, 2005-02-17) Mershin, AndreasTubulin, microtubules and associated proteins were studied theoretically, computationally and experimentally in vitro and in vivo in order to elucidate the possible role these play in cellular information processing and storage. Use of the electric dipole moment of tubulin as the basis for binary switches (biobits) in nanofabricated circuits was explored with surface plasmon resonance, refractometry and dielectric spectroscopy. The effects of burdening the microtubular cytoskeleton of olfactory associative memory neurons with excess microtubule associated protein TAU in Drosophila fruitflies were determined. To investigate whether tubulin may be used as the substrate for quantum computation as a bioqubit, suggestions for experimental detection of quantum coherence and entanglement among tubulin electric dipole moment states were developed.Item WIND-DRIVEN NEAR INERTIAL OCEAN RESPONSE AND MIXING AT THE CRITICAL LATITUDE(2010-07-14) Zhang, XiaoqianThe spatial structure and temporal evolution of sea breeze and the latitudinal distribution of propagation and mixing of sea breeze driven near-inertial ocean response in the Gulf of Mexico are investigated using comprehensive data sets and a non-linear numerical model. Near 30?N, inertial oceanic response is significantly enhanced by a near-resonant condition between inertial and diurnal forcing frequencies. Observational results indicate that sea breeze variability peaks in summer and extends at least 300 km offshore with continuous seaward phase propagation. The maximum near-inertial oceanic response occurs in June when there is a shallow mixed layer, strong stratification, and an approximately 10-day period of continuous sea breeze forcing. Near-inertial current variance decreases in July and August due to the deepening of the mixed layer and a more variable phase relationship between the wind and current. River discharge varies interannually and can significantly alter the oceanic response during summer. During 1993, the ?great flood? of the Mississippi River deepens the summer mixed layer and reduces the sea breeze response. The near-inertial currents can provide considerable vertical mixing on the shelf in summer, as seen by the suppression of bulk Richardson number during strong near-inertial events. Three-dimensional idealized simulations show that the coastal oceanic response to sea breeze is trapped poleward of 30? latitude, however, it can propagate offshore as Poincare waves equatorward of 30? latitude. Near 30? latitude, the maximum oceanic response to sea breeze moves offshore slowly because of the near-zero group speed of Poincare waves at this latitude. The lateral energy flux convergence plus the energy input from the wind is maximum near the critical latitude, leading to increased vertical mixing. This local dissipation is greatly reduced at other latitudes. Simulations with realistic bathymetry of the Gulf of Mexico confirm that a basin-wide ocean response to coastal sea breeze forcing is established in the form of Poincare waves. This enhanced vertical mixing is consistent with observations on the Texas-Louisiana Shelf. Comparison of the three-dimensional and one-dimensional models shows some significant limitations of one-dimensional simplified models for sea breeze simulations near the critical latitude.Item Wireless power transfer in the classroom(2013-08) O'Dell, David Harrison; Ling, HaoTraditional methods of teaching magnetic induction with lab investigations using a battery, wire and compass are best reserved for demonstration purposes to introduce this particular topic. The modern student who sits in a physics course also lives in a world filled with an increasing number of small portable devices that will eventually be charged wirelessly using some form of magnetic induction. The topic of magnetic induction needs to be placed in the modern context it deserves since the future of transmitting power will eventually be through wireless means. The wireless power transfer kit described in this report is designed to improve student understanding and the application of magnetic induction in an engaging, relevant manner.