Recursos de colección

DSpace at MIT (104.280 recursos)

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Physics - Master's degree

Mostrando recursos 1 - 20 de 119

  1. Steady states in rapidly evolving populations

    Melissa, Matthew (Matthew J.)
    Populations are subject to mutations conferring beneficial effects, as well as mutations conferring deleterious effects. Even if deleterious mutations occur much more frequently than beneficial mutations, the contribution of deleterious mutations to the overall rate of change of the population-wide mean fitness may be limited, due to the efficient action of selection. However, in particularly rapidly evolving populations, the stochastic accumulation of deleterious mutations may negate a significant fraction of the fitness increments provided by beneficial mutations, or even result in an overall decrease in fitness over time. Here we obtain a constraint on beneficial and deleterious mutation rates and...

  2. Optical properties of ultra-thin niobium nitride films for single photon detectors

    Archer, Lucy Elizabeth
    In this thesis I made a study of the properties of reactively sputtered ultra-thin films of niobium nitride (NbN) and niobium titanium nitride (NbTiN). Using Variable Angle Spectral Ellipsometry (VASE), I found that the optical properties of NbN films appear to have a critical thickness above which the optical parameters stabilize. I also found that the deposition process has better stability over time for thicker films than for thinner ones; that is, when films are deposited weeks apart, the thinner films show more variation in thickness and optical properties than do the thicker films. The data also suggest that the...

  3. Total mass of a patch of a matter-dominated Friedmann-Robertson-Walker universe

    Geller, Sarah (Sarah R.)
    In this thesis, I have addressed the question of how to calculate the total relativistic mass for a patch of a spherically-symmetric matter-dominated spacetime of negative curvature. This calculation provides the open-universe analogue to a similar calculation first proposed by Zel'dovich in 1962. I consider a finite, spherically-symmetric (SO(3)) spatial region of a Friedmann-Robertson-Walker (FRW) universe surrounded with a vacuum described by the Schwarzschild metric. Provided that the patch of FRW spacetime is glued along its boundary to a Schwarzschild spacetime in a sufficiently smooth manner, the result is a spatial region of FRW which transitions smoothly to an asymptotically...

  4. On the dynamics of bouncing droplets in confined geometries

    Cristea-Platon, Tudor
    The realm of the dynamics of bouncing droplets is a rather recent development in physics and mathematics. Just over a decade old, it holds many exciting avenues of exploration. In this thesis, I will present my research on millimetric liquid droplets, which walk across the surface of a vibrating fluid bath through a resonant interaction with their own wave fields. These walking droplets, or 'walkers', exhibit several features previously thought to be peculiar to the microscopic, quantum realm. In particular, walkers in confined circular corrals exhibit a wave-like statistical behaviour similar to that of electrons inside quantum corrals. My results...

  5. Inertial tearing modes in magnetically-confined plasmas

    Montag, Peter Katsumi
    In this thesis, I analyzed the behavior of the plasma instability known as the tearing mode in parameter regimes relevant to magnetically-confined fusion plasmas. This included a derivation of the relevant equations and a method of solving them using Fourier analysis. This method allowed the derivation of several analytic results and efficient calculation of numeric results about the growth rates and frequencies of the analyzed modes, and demonstrated the existence of a second type of unstable tearing mode related to electron inertia. The results of the analysis of this inertial mode proved consistent with experimental data on the tearing mode...

  6. The thermal conductivity of magnesium between one and four degrees Kelvin

    Sharkoff, Eugene G. (Eugene Gibb)
    by Eugene G. Sharkoff.

  7. Topics on electron,neutrino and axion scattering

    Mohanmurthy, Prajwal
    Under the broad topic of scattering, in this thesis we particularly investigate Lorentz invariance using Compton Scattering at the Compton Polarimeter located in Hall-C at Thomas Jefferson National Accelerator Facility. The Mississippi State Axion Search, an axion search experiment which uses light shining through a wall technique is described in detail, including its instrumentation, initial tests and future impact. Furthermore, a novel method of detection of solar anti-neutrinos based on coherent neutrino scattering is described. Additionally, on the instrumentation side, development of a multi-purpose beam instrument based on synchrotron light to measure the electron beam polarization, beam profile and intensity...

  8. The photoelastic properties of celluloid, glass, and fused quartz

    Allis, William P. (William Phelps), 1901-1999
    by William Phelps Allis.

  9. Extreme optomechanically induced transparency

    Bodiya, Timothy Paul
    This thesis describes the theory and experimental implementation optomechanically induced transparency utilizing ultra low loss mechanical oscillators and high laser power to achieve extremely strong optical induced transparency effects. This system modifies the light transmission properties of the optical cavity reducing the transmission by a factor of 3 x 10 -3 at the highest power levels. A linewidth reduction of 5 x 10 -5, from 10 kHz to 20 mHz, has been achieved.

  10. Learning experiments in a MOOC (Massive Open Online Course)

    Chudzicki, Christopher A
    We present results from two treatment / control experiments in the 8.MReV: Mechanics ReView massive open online course (MOOC) run on edX.org during summer 2014. We compare the efficacy of physics homework problems: (1) traditional physics problems involving many skills, (2) deliberate-practice activities that train individual skills using the drag-and-drop format, and (3) analogous deliberate practice activities in multiple choice format. Using a common assessment, our results suggest that traditional instruction is more effective than deliberate practice activities cast in the multiple-choice format; comparison of traditional problems and drag-and-drop deliberate practice is so far inconclusive. Some evidence suggests users prefer...

  11. Microfabrication of surface electrode ion traps for quantum manipulation

    Ge, Yufei, S.M. Massachusetts Institute of Technology
    Trapped ions are a promising approach to quantum computation. This approach uses a qubit state which is the atomic state and quantum motional state of a trapped ion to encode information, and uses laser-ion interactions to manipulate the qubit state. A major obstacle to the realization of a practical ion trap quantum computer is decoherence. In trapped ion quantum computation experiments, decoherence is dominated by the uncontrolled heating of ion motional states. In this thesis, we present the detailed microfabrication of several series of surface electrode linear Paul traps made from different electrode materials, followed by the ion motional heating...

  12. Testing the Leggett-Garg inequality with solar neutrinos

    Murskyj, Mykola
    One of the fundamental questions in quantum physics is whether measurements reveal pre-existing values. Leggett and Garg derived an inequality that is satisfied by systems featuring both macroscopic realism and non-invasive measurability. The Leggett-Garg Inequality places a quantum-classical limit on a linear combination of correlation functions of a series of measurement outcomes. The flavor oscillations of solar neutrinos provide an interesting way to test the Leggett-Garg inequality, and on an astrophysical length scale. Beginning as electron neutrinos in the solar core, they undergo the Mikheyev-Smirnov-Wolfenstein Effect and exit the sun in either of two mass eigenstates, depending on their energy....

  13. Simulations and technology development for time-domain astronomy : TESS and InGaAs detectors

    Sullivan, Peter William
    Optical time-domain astronomy is in the midst of significant developments due to new instruments, data processing techniques, and space missions. The Kepler mission has identified thousands of exoplanet systems with the transit technique, allowing the first statistical analyses of the exoplanet population. The upcoming Transiting Exoplanet Survey Satellite (TESS) mission will complement Kepler by identifying the brightest transiting exoplanet systems on the sky. These planets will offer the most insight into their radius, mass, and composition. At approximately the same time that TESS launches, the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) will reach full operation, allowing the detection of gravitational...

  14. Flow of [phi] mesons in pPb collisions at the LHC with the CMS detector

    Varma, Mukund Madhav
    Measurements of two-particle angular correlations between unidentified charged particles and [phi]-mesons are shown over a wide pseudorapidity range ([delta] [eta] < 2) in pPb collisions. The data, collected during 2013 pPb run at a nucleon-nucleon center-ofmass energy of 5.02 TeV with the CMS detector, corresponds to a total integrated luminosity of aproximately 35nb-1. [Phi]-mesons are reconstructed via their hadronic decay channel, [phi] --> K+K-, for high multiplicity events. The observed two-particle long range correlations are quantified by the second-order Fourier coefficients (v2) as a function of transverse momentum. The v2 of [phi]-mesons is compared to that of other identified particles,...

  15. The centrifugal distortion coefficients of the molecule hydrogen deuterium oxide

    Lewis, William Hargrove
    by William Hargrove Lewis.

  16. Comparison of edge turbulence velocity analysis techniques using Gas Puff Imaging data on Alcator C-Mod

    Sierchio, Jennifer Marie
    In the past, two methods for analyzing data from the Gas Puff Imaging diagnostic on Alcator C-Mod have been used. One uses temporal and spatial Fourier analysis to obtain wavenumber-frequency spectra, from which a phase velocity is computed [1, 2]. The other is based on time-delay cross-correlation of successive images used to track the motion of discrete emission structures [3, 4]. Several Gas-Puff-Imaging experiments were conducted to obtain data taken using the GPI Phantom Camera. The analysis of and results from these data are discussed in [3]. The results showed that the tracking time-delay-estimation technique found poloidal velocity magnitudes in...

  17. Density perturbations in hybrid inflation

    Son, Nguyen Thanh
    Inflation is a substantial modification to the big bang theory, and supernatural inflation is a hybrid inflation motivated from supersymmetry. In this thesis we carry out a one dimensional numerical simulation to verify the untested analytic approximation of Radall et al. The results show a good agreement for a wide range of parameters. We also propose a new method for calculating density perturbations in hybrid inflation, which shows an excellent agreement with the simulation in one dimension.

  18. Synthesis and characterization of single crystal kagomé lattice antiferromagnets

    Han, Tianheng, Ph. D. Massachusetts Institute of Technology
    An ideal spin-% kagomé lattice has been a long sought material. This system is characterized by strong magnetic frustration and is a likely candidate for a spin-liquid ground state. The spin-liquid state was originally proposed to exist in the parent compounds of the high temperature superconducting cuprates as originally proposed by Anderson. However, the lack of ideal samples have hampered experimental tests of the theories. A few years ago, a kagomé lattice material called herbertsmithite (ZnCu3(OH)6Cl2) has been successfully synthesized and studied. Since then, many experiments have been performed which have produced a lot of new guidance for our theoretical...

  19. Numerical calculation and data visualization tool for cosmological physics : QuintET

    Tekle, Ephraim Adane, 1974-
    by Ephraim Adane Tekle.

  20. The Casimir energy in a separable potential

    Williamson, Lyndie Ruth, 1974-
    by Lyndie Ruth Williamson.

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