Other Physics Commons^™

Thermoelectric Single-Photon Detectors For X-Ray/Uv Radiation, G. G. Fritz, K. S. Wood, D. Van Vechten, A. L. Gyulamiryan, A. S. Kuzanyan, N. J. Giordano, T. M. Jacobs, H.-D. Wu, J. S. Horwitz, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

A feasibility study of megapixel microcalorimeter arrays, based on thermoelectric energy to voltage conversion and digital superconducting readout, is presented. The design concept originated from the philosophy of employing the simplest principles at the single-pixel level to enable large arrays without sacrificing energy resolution, fast operation speed, and quantum efficiency. Initial experimental tests confirm the basic predictions of theory, and show no major obstacle in achieving the desired characteristics.

Two-Level Atom In An Optical Parametric Oscillator: Spectra Of Transmitted And Fluorescent Fields In The Weak Driving Field Limit, James P. Clemens, Perry R. Rice, Pranaw Kumar Rungta, Robert J. Brecha

Physics Faculty Publications

We consider the interaction of a two-level atom inside an optical parametric oscillator. In the weak-driving-field limit, we essentially have an atom-cavity system driven by the occasional pair of correlated photons, or weakly squeezed light. We find that we may have holes, or dips, in the spectrum of the fluorescent and transmitted light. This occurs even in the strong-coupling limit when we find holes in the vacuum-Rabi doublet. Also, spectra with a subnatural linewidth may occur. These effects disappear for larger driving fields, unlike the spectral narrowing obtained in resonance fluorescence in a squeezed vacuum; here it is important that …

Time Domain Measurement Of The Nonlinear Refractive Index In Optical Fibers And Semiconductor Film, Hernando Garcia

Dissertations

A new technique to measure the nonlinear refractive index n₂ in optical fibers and semiconductor films has been developed. It is based on the time delay two-beam coupling of very intense picosecond laser pulses that have been self-phase modulated in the nonlinear optical medium. The two beams are coupled in a slow responding medium that is sensitive to time dependent phase distortions. We determine that the amount of phase distortion experienced by the pulse is proportional to the nonlinear refractive index of the medium, This time domain approach can also be applied to optical fiber amplifiers in the presence …

Modeling, Design And Fabrication Of Thin-Film Microcrystalline Silicon Solar Cells, Wei Chen

Dissertations

The modeling, design and fabrication of low-cost thin-film microcrystalline silicon(µcSi) solar cells is studied in this thesis. The cell, considered in this investigation, utilizes low-cost glass as the substrate and microcrystalline Si (µc-Si) as the active layer. A comprehensive refractive index (n) and extinction coefficient (k) model of silicon as function of doping, temperature and wavelength is developed to assist the optical design of the cell. In order to obtain acceptable short circuit current density (Jsc) from the cell, it is found that the thickness of the silicon thin film should be more than 10µm. To get the best light …

Testing Of The New Usgs K Index Algorithm At Bear Lake Observatory, Ariel O. Acebal

Theses and Dissertations

The K index was developed by Bartels in 1939 as an estimate of the level of geomagnetic activity caused by the Sun. This index was computed manually every three hours at geomagnetic observatories using the magnetic traces of the surface planetary magnetic field. In 1991, the International Association of Geomagnetism and Aeronomy approved four additional methods to compute the K index; all of them were computer algorithms. One of the approved methods, the Wilson code, recently underwent some modifications. The new algorithm is now part of a Windows-based computer program being developed by the United States Geological Survey (USGS). After …

Experimental And Phenomenological Study Of Persistent Photoconductivity In Yba2cu3o6 Thin Films, Daniel-Dennis Mcalevy Bubb

Dissertations

Persistent Photoconductivity in YBa₂Cu₃O_6+x thin films is studied by means of infrared photoconductivity measurements after the films have been illuminated with visible light at low temperature. Experimentally, the effect is characterized by the samples' electrical response to infrared light, either causing the resistance to decrease or increase.

A cellular automata model is proposed in explanation of these results and is shown to be consistent with current experimental understanding of this unusual effect, both our results and those of others. The cellular automata model may have application to other unusual optical phenomena exhibited by YBa_{2 …}

Placement Of Bright S88b Objects On A Hertzprung-Russel Diagram Using Visible Light Measurements, Geoffrey A. Bonvallet

Physics Senior Independent Study Theses

Thesis digitized from Physics Department I.S. Archive.

Erratum: "Cell Size Dependence Of Transport Coefficients In Stochastic Particle Algorithms", Alejandro Garcia, F. Alexander, B. Alder

Faculty Publications

No abstract provided.

Time Step Truncation Error In Direct Simulation Monte Carlo, Alejandro Garcia, W. Wagner

Faculty Publications

No abstract provided.

Energy Losses Of Solar Neutrinos, Zamri Zainal Abidin

Student Works (2000-2009)

Using the stopping power of matter. the effects of oscillations on the energy losses of solar neutrinos are investigated. The adiabatic and non-adiabatic survival probabilities of the neutrino oscillations, the mixing angles and Am² are the parameter.; in the calculations. The total energy losses for ⁸B neutrinos with maximum spectral energy of 14.06 MeV is 5 x 10⁻⁷ MeV and is slightly lower than the losses from the non-adiabatic conversion which is ~7 x 10⁻⁷ MeV. From the calculation, we found that the maximum total energy loss for solar neutrinos is of the order 10⁻⁶ MeV. We also include the …