Filtering by
- All Subjects: vortices
- Creators: Keeler, Cynthia
This paper outlines the design and testing of a z-scan spectrometer capable of measuring the third order refraction index of liquids. The spectrometer underwent multiple redesigns, with each explored in this paper with their benefits and drawbacks discussed. The first design was capable of measuring the third order refraction index for glass, and found a value of 8.43 +- 0.392 x 10^(-16) cm^2/W for the glass sample, with the literature stating glass has a refraction index between 1-100 x 10^(-16) cm^2/W. The second design was capable of measuring the third order refraction index of liquids, and found values of 1.23 $\pm$ 0.121 $\e{-16}$ and 9.43 +- 1.00 x 10^(-17) cm^2/W for water and ethanol respectively, with literature values of 2.7 x 10^(-16) and 5.0 x 10^(-17) cm^2/W respectively. The third design gave inconclusive results due to extreme variability in testing, and and the fourth design outlined has not been tested yet due to time constraints.
investigations into the interactions involving topological defects, such as
magnetic monopoles and strings, that may have been produced in the early
universe. I performed numerical studies on the interactions of twisted
monopole-antimonopole pairs in the 't Hooft-Polyakov model for a range of
values of the scalar to vector mass ratio. Sphaleron solution predicted by
Taubes was recovered, and I mapped out its energy and size as functions of
parameters. I also looked into the production, and decay modes of $U(1)$ gauge
and global strings. I demonstrated that strings can be produced upon evolution
of gauge wavepackets defined within a certain region of parameter space. The
numerical exploration of the decay modes of cosmic string loops led to the
conclusions that string loops emit particle radiation primarily due to kink
collisions, and that their decay time due to these losses is proportional to
$L^p$, where $L$ is the loop length and $p \approx 2$. In contrast, the decay
time due to gravitational radiation scales in proportion to $L$, and I
concluded that particle emission is the primary energy loss mechanism for loops
smaller than a critical length scale, while gravitational losses dominate for
larger loops. In addition, I analyzed the decay of cosmic global string loops
due to radiation of Goldstone bosons and massive scalar ($\chi$) particles.
The length of loops I studied ranges from 200-1000 times the width of the
string core. I found that the lifetime of a loop is approximately $1.4L$. The
energy spectrum of Goldstone boson radiation has a $k^{-1}$ fall off, where $k$
is the wavenumber, and a sharp peak at $k\approx m_\chi/2$, where $m_\chi$ is
the mass of $\chi$. The latter is a new feature and implies a peak at high
energies (MeV-GeV) in the cosmological distribution of QCD axions.