Bulletin of the American Physical Society
2005 TSAPS/AAPT/SPS Joint Fall Meeting
Thursday–Saturday, October 20–22, 2005; Houston, TX
Session C1: General Experimental III |
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Room: Shamrock Main 261M |
Friday, October 21, 2005 3:00PM - 3:12PM |
C1.00001: Target-thickness Dependence of Bremsstrahlung from Solid Al and Au Films Scott Williams, C.A. Quarles The results of a study of the target thickness-dependence of bremsstrahlung from solid films are presented, along with comparisons of the ratios of the data for different target thicknesses with the ratios obtained using the Monte Carlo code PENELOPE. The electron beam energy used in the experiments is $\sim $55 keV and bremsstrahlung is observed at an angle of 90$^{o}$. The targets used were made of gold and aluminum, with thicknesses ranging from 30 $\mu $g/cm$^{2}$ (where single interaction conditions apply) to about twice the electron range (where a multiple interaction model applies). The purpose of the study is to observe the transition from thin to thick film spectra and to investigate whether the polarization bremsstrahlung contribution is suppresses in solid film targets. [Preview Abstract] |
Friday, October 21, 2005 3:12PM - 3:24PM |
C1.00002: Multiple Scattering of Terahertz Radiation in a Random Medium Kevin Doyle, J. Pearce, Z. Jian, J. Deibel, D. Mittleman Terahertz (THz) radiation, radiation on the borderline between microwave and infrared, possesses some interesting properties that could lead to new biomedical imaging techniques. Unlike the typical optical pulse which contains several wavelengths, the THz pulse contains only one wavelength, allowing optical sensors to measure the electric field directly, rather than just the intensity, along with the phase information. Because of this, a thorough understanding of the statistics of THz scattering in a random medium could lead to imaging methods combining aspects of both optics and electronics. Using a sample cell of Teflon spheres as our random medium, the diffusive scattering of a THz pulse was measured. By plotting histograms of the electric field for different configurations of spheres at specific time intervals, it was found that the electric field measured at a certain time was random, but the range of possible values for the electric field changed with time according the photon time-of-flight distribution. [Preview Abstract] |
Friday, October 21, 2005 3:24PM - 3:36PM |
C1.00003: Interaction of Gas Molecules with Various Porous Materials Loaded in a Microwave Resonant Cavity to Sense Airborne Toxins Aman Anand, James Roberts, Jai Dahiya, McDaniel Floyd A microwave resonant cavity in the TM$_{010}$ mode was used as a probe to study the gas absorption in Single Walled Carbon Nanotubes and other porous material with high surface area to mass ratio. The microwave Network Analyzer was used in this investigation to study the gas absorption effects as a function frequency and pressure of the gas flown into the system. All experiments have been conducted at room temperature. Wide ranges of gases (both polar as well as non-polar) were used in this experiment for the comparison of absorption effects between various porous samples. Each experiment was repeated three times to ensure the validity of the data taken. The data were analyzed with polynomial fit plots. In the experiment, the effects of absorbed impurities on the magnetic and electric field vectors in a resonant cavity loaded with CNTs were monitored using standard perturbation techniques. This interaction is described by the equation, Z = f$_{1}(\mu _{e}$, \textbf{E})-f$_{2}(\mu _{m}$, \textbf{H}), where f$_{1}(\mu _{e}$, \textbf{E}) is a function of the electric permeability $\mu _{e}$ and the electric field, while f$_{2}(\mu _{m}$, \textbf{H}) is a function of the magnetic permeability $\mu _{m}$ and the magnetic field. Gas absorption during irradiation of the CNTs affects the load in the resonant cavity, produces the frequency shifts [Preview Abstract] |
Friday, October 21, 2005 3:36PM - 3:48PM |
C1.00004: Characterization of optical properties of human ocular tissues Cody Coeckelenbergh, Guang-Yin Swanland, Raylon Yow, Dhiraj Sardar An in-depth characterization of optical properties of various tissue components of human eye has been performed. The total diffuse reflection and total transmission are measured on tissues by using spheres and infrared laser diodes. The indices of refraction of tissues were also measured. The Inverse Adding Doubling (IAD) method is applied to the values of n, R$_{d}$, and T$_{t}$ to determine the optical absorption and scattering coefficients of the human ocular tissues. The scattering anisotropy value was determined by iteratively running the IAD program and a Monte-Carlo simulation of light-tissue interaction until the minimum difference in experimental and computational values for R$_{d}$ and T$_{t}$ were realized. [Preview Abstract] |
Friday, October 21, 2005 3:48PM - 4:00PM |
C1.00005: Random Co-polymer Brushes: on Silicon; and on Amorphous Silicon Carbide on Silicon William Gibson, Guy Hilburn, Richard Griffin, Jeremy Jarl, Eric Botello, Elizabeth Covington, Phillip Hartnet, Deborah Koeck, David Donnelly, Heather Galloway, Suresh Murugesan, Gary Beall, Chad Booth, Patrick Cassidy Deposition of random copolymer (RCP) brushes is a standard surface preparation for deposition of diblock copolymers on Si and related surfaces. We did a comparative study of cleaning methods for substrate preparation, and optimized the procedures for deposition of P(S-r-MMA) on Si, and amorphous SiC films on Si substrates. In both cases, we found a minimum anneal time of 8 h. We found no relation between RCP concentration in solution and ultimate RMS roughness. We found a successful non-destructive method for verification of RCP presence on both Si and SiC on Si substrates. We also found Super Critical CO$_{2}$ to be an effective alternative rinse method for removal of excess RCP after anneal [Preview Abstract] |
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