Department of Physics (Fredericton)

Pages

An investigation of the properties of the GaAs diode laser
An investigation of the properties of the GaAs diode laser
by Rodney Mark McInnis, The purpose of this project is to operate a commercial diode laser within its specifications and study a few properties within the framework of elementary physics calculations. The laser diodes used have some restrictive power supply parameters and exceeding them can easily destroy a laser. Experimental objectives could only be achieved after several pieces of electronic equipment were designed and built, such as the temperature regulator, Hex. display, avalanche photodiode detector and power supply, and laser power supply. Upon completion of the hardware, the diode laser was examined under the following experiments: -spectral distribution above and below threshold current -mode structure - peak wavelength as a function of temperature - spectral distribution at different peak currents -beam divergence -threshold current as a function of temperature
Atmospheric parameters derived using an elastic backscatter L.I.D.A.R. system
Atmospheric parameters derived using an elastic backscatter L.I.D.A.R. system
by David Donovan, L.I.D.A.R is an acronym for light detection and ranging, and is a powerful active technique for remote sensing the atmosphere. Lidar may be said to be the optical equivalent of radar, it is in fact often referred to as "laser radar". In this paper remote sensing of the atmosphere via elastic backscatter LIDAR is discussed and elastic backscatter LIDAR data obtained using a powerful ND-YAG LIDAR at York University in Toronto Ontario is evaluated and discussed, 2 unnumbered pages before first numbered page
Calcium uptake in vitro by beef heart mitochondria under the influence of Adriamycin
Calcium uptake in vitro by beef heart mitochondria under the influence of Adriamycin
by Janet L. Reid, Adriamycin, an antibiotic which has proven to be a clinically useful chemotherapeutic agent against cancer, is found to produce fatal, dos~-related cardiac toxicity in man. Although the mechanism of this adriamycin-induced cardiomyopathy remains elusive, structural studies of affected patients and laboratory animals indicate that Adriamycin causes delayed structural alterations in the form of myocardial lesions. Recent studies have demonstrated elevated levels of calcium in tissue affected by Adriamycin, and microscopic examination of the degenerating heart tissue reveals mitochondrial degeneration and dense body formation within mitochondria in the form of calcium phosphate deposits. Therefore, it was decided to investigate the effect of Adriamycin upon calcium uptake in vitro by beef heart mitochondria, and to see how the combination of Adriamycin and A-23187 (which has a known effect upon calcium flux) affect mitochondrial calcium movement. Results obtained in this paper indicate that Adriamycin induces accumulation of calcium by heart mitochondria. Crucial to this study was the technique of atomic absorption spectroscopy used to determine calcium concentration which is based upon the absorption of energy by valence electrons of ground state calcium atoms. Use of a nitrous oxide-acetylene flame (hot) as opposed to an air-acetylene flame (cooler), based on the interference relevant in each case) is briefly discussed.
Calculation of the phase-transition point in an optical parametric amplifier
Calculation of the phase-transition point in an optical parametric amplifier
by Jeffery S. Banford, The phase transition point for sub-harmonic generation of an optical parametric amplifier was calculated; this is the point at which squeezing of the sub-harmonics is maximum. This was done by numerically solving a system of coupled integral equations.
Cavity ringdown laser absorption spectroscopy of a radio frequency discharge
Cavity ringdown laser absorption spectroscopy of a radio frequency discharge
by Clark Richards, Cavity ringdown spectroscopy is a direct absorption technique performed with laser sources that has higher sensitivity than many other absorption techniques. It measures the rate rather than the magnitude of absorption of a molecule in a high reflectance cavity. By scanning the laser over a range of frequencies, the absorption spectrum for the molecule can be determined. The goal of this thesis is to combine the cavity ringdown technique with an rf discharge, so as to study molecules such as free radicals, without the difficulties and uncertainties associated with the previously used laser optogalvanic technique. The sensitivity and applicability of the technique have been demonstrated by measuring a molecular band of the formyl radical (HCO) with an absorption sensitivity greater than 1 part in 10(6), and comparing it to that taken with laser optogalvanic spectroscopy.
Computer simulation of a phase locked laser diode array
Computer simulation of a phase locked laser diode array
by D. W. Boertjes, Pages are unnumbered.
Conical SPRITE: A rapid, 3D MRI method for imaging solid-like materials
Conical SPRITE: A rapid, 3D MRI method for imaging solid-like materials
by Meghan Halse, Conical SPRITE is introduced as a rapid, 3D, proton-density weighted single point imaging technique for the study of solid-like materials with short relaxation times. The development and implementation of this technique is discussed along with a point spread function analysis of the convolution blurring effect of the combined effects of the sampling method and magnetization relaxation. Experimental results are presented that demonstrate the speed of acquisition, the dependence of signal to noise and resolution on flip angle, and the potential for manipulation of contrast through the use of magnetization preparation., 30 unnumbered pages after last numbered page
Contrast in Magnetic Resonance Images of chemical waves associated with the Belousov-Zhabotinsky reaction
Contrast in Magnetic Resonance Images of chemical waves associated with the Belousov-Zhabotinsky reaction
by Andrea S. Reid, The determinants of contrast in magnetic resonance images of chemical waves, associated with the manganese-catalyzed BZ reaction, were investigated by studying the role of ortho-, pyro-, and meta-phosphates in the stabilization the Mn3+ ion. Relaxation times, T1 and T2, were measured for BZ reaction mixtures containing each of the phosphates (H3P04 , Na3P04 , Na4P20 7 , Na5P30 10 ) at several concentrations and over a range of time. These parameters were measured for both the "reduced" and "oxidized" states of manganese in the reaction. It is concluded that the pyro-phosphate, Na4P20 7, is the most suitable compound for MRI studies of chemical waves, particularly for studies of 3-D structures, in this system.
Correlation of underwater ambient noise
Correlation of underwater ambient noise
by Andrew Rosenfeld, The study of ambient n01se m the ocean has long been of interest to those involved in oceanography and naval research, as it relates to both underwater environmental processes and the performance of sonar systems. One of the more important aspects is the study of noise correlation between sensors, which is of particular interest because it can impart a directionality to the overall ambient noise field. Advanced sonar systems can be developed to take advantage of this directionality, filtering out waves exterior to the region of interest. This report summarizes the basic theory behind ambient noise correlation, and then develops from these basics various Monte Carlo simulation approaches of practical value. The final section discusses superdirective array processing, an advanced application of the preceding theory and simulations.
Deuterium NMR spectroscopy of CD30D adsorbed on deuterated cellulose
Deuterium NMR spectroscopy of CD30D adsorbed on deuterated cellulose
by Marc A. MacKenzie, The technique of pulse Nuclear Magnetic Resonance (NMR) was used to determine the T1, T1P, T2FID and T2CP deuteron relaxation times for deuterated methanol on deuterated cellulose ( with ad -methanol content of 0.198 grams of d - methanol per gram of cellulose ) . The temperature range studied was 133 K to 291 K using a resonant frequency of 30. 513 Mhz and a B1 locking field of 10G for the T1P measurements. The T1, T1P and T2CP relaxation times each had two components, and the T2FID relaxation time displayed a single component. The ratio of the fractions of the spins relaxing with the three long components to the fractions for the corresponding short components was seen to be approximately three to one; this is seen to relate the CD3 group to the long component, and the short component to the OD part of the methanol. The model used to describe the molecular motion was a bimodal distribution of correlation times, with the two modes corresponding to two distinct binding sites on the cellulose molecule. For room temperature , the correlation times ( Tc and activation energies calculated from this model are 6 . 8 x 10-10 s-1 , 2.000 kcals/mol ( tf, fast mode ) and 6.9 x 10-8 s-1 , 3.000 kcals/mol ( t5 , slow mode ) for the long component; for the short component, the calculated values are 3 .5 x 10-10 s-1 , 2.2 kcals/mol ( fast mode ) and 3.3 x 10-8 s-1, 1.000 kcals/mol ( slow mode ).
Development of a high frequency broadband photodetector for use in a distributed temperature sensor and studies of Brillouin scattering in single-mode optical fibre
Development of a high frequency broadband photodetector for use in a distributed temperature sensor and studies of Brillouin scattering in single-mode optical fibre
by Anthony Wayne Brown, A broadband and high frequency transimpedance amplifier with a 1300 nm photodetector for use in a distributed temperature sensing system based on stimulated Brillouin scattering was designed, built and tested. The bandwidth of such an amplifier has been shown to be on the order of 1 GHz, with 40 dB power gain and NEP of 11 pW/Hz1/2. The characteristics of fibre attenuation, Brillouin frequency shift and stimulated Brillouin scattering threshold power have been studied in single mode optical fibres.

Pages

Zircon - This is a contributing Drupal Theme
Design by WeebPal.