Physics & Astronomy Undergraduate Honours Theses
http://hdl.handle.net/2429/547
2015-03-27T12:41:09ZBorn-Infeld action geometries (Issued:2014-05-31)
http://hdl.handle.net/2429/50709
In this thesis, we present a novel way of studying noncommutative geometries in string theory based on an effective Hamiltonian given by Berenstein and Dzienkowski[1]. We work in the context of the study of two magnetic monopoles deforming a D3 brane as considered by Karczmarek and Sibilia[2]. We present numerical evidence that for surfaces defined using n-dimensional generators of the SU(2) algebra in an auxiliary Hilbert space with this effective Hamiltonian, the surface represents a set of eigenvalues for 2n-dimensional eigenvectors that demonstrate the property of splitting into two parallel n-dimensional sub-eigenvectors. We conjecture that these sub-eigenvectors can then be used to study coherent states in these noncommutative geometries based on the the fact that the annihilation operator appears in block form in the effective Hamiltonian acting on the eigenvector. Lastly, we derive a useful formula for studying the geometric rate of change of these 3-dimensional surfaces in 4 dimensions that may prove handy in preparing numerical solutions of the Nahm equation.
2014-05-31T00:00:00ZSearching for solitons in the magnetosphere of a magnetar (Issued:2013-04)
http://hdl.handle.net/2429/46354
We describe a non-pertrubative method of searching for solitary waves travelling through the
magnetosphere of a magnetar. The wave will be supported by the combined effects of nonlinearity
and dispersion caused by the presence of a quantum electrodynamic (QED) vacuum in a strongly
magnetized field and by a strongly magnetized plasma of the magnetosphere. Using this method,
we have found a soliton in the form of an infinite current sheet. The method and the results of
this paper could be conducive to research studying the emission of strongly magnetized stars.
2013-04-01T00:00:00ZSingle color photoassociation spectroscopy of ⁶Li₂ and ⁸⁵Rb₂ (Issued:2012-09)
http://hdl.handle.net/2429/43353
Single color photoassociation (PA) of ⁸⁵Rb₂ and ⁶Li₂ was achieved in an optical dipole trap with the goal of measuring new vibrational levels of the 1³∑g state of ⁶Li₂. Initial benchmark tests using Rb were performed to determine the optimum conditions for observing photoassociation on the apparatus: >.5 kW/cm² PA laser intensity, high density, low temperature (∼ 10ɲK), and long hold times (>1s). These tests with Rb also revealed discrepancies between dipole trap PA data and spectra taken in a magneto-optic trap on another experiment (MAT).
Initial calculations for the locations of the ⁶Li₂ lines were carried out using fitted
potentials provided to us by Nikesh Dattani [5]. We observed seven ⁶Li₂ PA lines that were within 1 cm⁻¹ of the predicted values. Because of this good agreement between theory and measurement for all seven lines, we are confident that these lines are indeed vibrational levels of the 1³∑g state of Li₂. Additional studies of two of these peaks revealed five or six-fold splitting due to the magnetic field.
2012-09-01T00:00:00ZPhotonuclear Sum Rules for 6He. (Issued:2011)
http://hdl.handle.net/2429/37311
We perform the ab-initio calculation of photonuclear sum rules for 4He and 6He
using semi-realistic potentials. Our results include the first ab-initio calculation
of the electric polarizabililty of 6He. We perform the calculation by expanding the
the wavefunctions in a Hyperspherical Harmonic basis and solving the Schr¨odinger
equation exactly. Model space trunction effects are estimated by incrementing the
size of the Hilbert space, and evaluating the convergence pattern. We also compute
sum rules by integrating the theoretically computed cross section available from the
literature. Full convergence is not yet achieved. A discussion of the preliminary
results is presented. Future work, taking advantage of negligible symmetries in the
hyperspherical harmonic basis, should be able to achieve full convergence.
2011-01-01T00:00:00Z