Recursos de colección

DSpace at MIT (104.280 recursos)

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Physics - Bachelor's degree

Mostrando recursos 1 - 20 de 463

  1. Generator-level acceptance for the measurement of the inclusive cross section of W-boson and Z-boson production in pp collisions at [square root of] s = 5 TeV with the CMS detector at the LHC

    Andriatis, Alexander
    The inclusive cross section of vector boson production in proton-proton collisions is one of the key measurements for constraining the Standard Model and an important part of the physics program at the LHC. Measurement of the inclusive cross section requires calculating the detector acceptance of decay products. The acceptance of the CMS detector of leptonic decays of W and Z bosons produced in pp colisions at [square root of]s = 5 TeV is calculated using Monte Carlo event simulation. Statistical and systematic uncertainties on the acceptance measurement from PDF and a, uncertainty and higher-order correction are reported. The use of...

  2. Surface characteristics of near-earth objects

    Hsia, Nancy P
    Asteroids are thought to be the source of all meteorites found on Earth. Numerous spectroscopic studies have been performed to try and link certain types of meteorites with certain classes of asteroids in space. However, these spectroscopic studies of meteorites and asteroids have often shown a discrepancy between the meteorite and asteroid spectra, with the asteroid spectra showing a higher red slope and less prominent absorption bands. This effect has been seen especially in the spectra of asteroids located in the main belt. Scientists now believe that space weathering processes, such as solar wind ion implantation and bombardment by micrometeorites,...

  3. Direction of spin of Koronis family member (1289) Kutaïssi

    Klesman, Alison J. (Alison June), 1981-
    Observations of lightcurve of Koronis family member asteroid (1289) Kutaïssi were taken in January, 2003, at MIT's Wallace Astrophysical Observatory. The goal of these observations included obtaining a precise rotation period and direction of rotation for the asteroid extracted from data obtained in two different filters. By combining the new data with data from previous epochs, a rotation rate and direction of spin were found; results give a period of 3.62424 ± 0.00001 hrs and the asteroid was found to be spinning retrograde to its orbital motion. The results obtained from this project will be useful in the future for...

  4. The role of eddies in buoyancy flux

    Ring, Michael J., 1979-
    This thesis explores the role of eddies in determining the stratification of the ocean through a laboratory experiment. The experiment uses a dual-tank apparatus, with a smaller tank sitting inside the larger tank. Both tanks sit on a rotating turntable, which simulates the rotation of Earth. During the experiment, salty water is pumped from the outer tank through small holes in the base of the inner tank, which is initially filled with fresh water. The evolution of the dense fluid in the inner tank is observed, with particular regard to the number of eddies that form. These observations are checked...

  5. Analyzing the large-scale curvature of interplanetary shocks

    Vogt, Marissa Farland
    The 3-dimensional structure of interplanetary shock surfaces are analyzed using observations from the Wind and ACE spacecraft. Events seen by both spacecraft were selected from the available data and used to calculate the radius of curvature R, of the shock surface. The surface structure was examined within the ecliptic plane, and evidence of large-scale curvature was seen when the spacecraft separation was sufficiently large. A simulation was run to test the effects of small errors in the shock normal, and showed that these errors could affect R, calculations at small separation. The radius of curvature was studied as a function...

  6. Heavy nuclides in cosmic radiation.

    Hallock, Geoffrey Gaddis
    Massachusetts Institute of Technology. Dept. of Physics. Thesis. 1969. B.S.

  7. Calculation of the axial charge of a heavy nucleon in Lattice QCD

    Pefkou, Dimitra Anastasia
    In this thesis, we aim to calculate the non-renormalized axial charge gA of a heavy nucleon made out of quarks at the physical mass of the strange quark. We present the framework of Lattice QCD which makes the calculation of such observables attainable from first principles. The data used for the estimation of gA were obtained on a 243 x64 hypercubic lattice with lattice spacing a ~ 0.12 fm and pion mass m[pi] = 0.450 GeV. Three different source-sink seperations were used, tsink = [12a, 14a, 16a]. For each timeslice seperation signal we perform a correlated x2 fit and obtain...

  8. Study of a short distance top mass with a cross-section at NNLL + NNLO

    Bachu, Brad
    We consider top-quarks produced at large energy in e+e- collisions and address the question of what top-mass can be measured from reconstruction. The production process is characterized by the center-of-mass energy, Q, the top mass, m, the top decay width, It, and also AQCD. These scales are well separated and can be disentangled with effective theory methods such as the Heavy-Quark Effective Theory and Soft-Collinear Effective Theory. We compute a top mass observable for future e+e- colliders to next-to-next-to-leading-logarithmic order + [Omicron] [alpha] 2/[sigma](NNLL+NNLO), which goes beyond previous next-to-leading-logarithmic + [Omicron] [alpha] 2/[sigma] (NLL+NLO) analysis. We use the two-loop heavy...

  9. Spin-orbit coupled Bose-Einstein condensates with observation of a stripe phase

    Burchesky, Sean
    In this work we build a new spin-orbit coupling experiment to observe the supersolidlike stripe phase. The phase diagram of a 1-dimensional spin-orbit coupled Bose- Einstein condensate shows several interesting phases including the stripe phase. We find the stripe phase particularly interesting because the condensate develops a density modulation in free space while remaining superfluid, which are the signature of supersolidity. In order to observe the stripe phase, we develop a novel spin-j basis which uses the orbital bands of an optical superlattice. Our choice of pseudo-spin basis allows the condensate components to remain miscible at high enough spin-orbit coupling...

  10. Resolution effects in the hybrid strong/weak coupling model

    Hulcher, Zachary R
    Within the context of a hybrid strong/weak coupling model of jet quenching, we study the consequences of the fact that the plasma produced in a heavy ion collision cannot resolve the substructure of a collimated parton shower within it to arbitrary resolution. We introduce a screening length parameter, LRes, proportional to the inverse of the local temperature in the plasma, estimating the value of the proportionality constant from both weakly coupled QCD calculations and holographic calculations appropriate in strongly coupled plasma. We then modify the hybrid model so that when a parton in a jet shower splits, its two offspring...

  11. Search for Higgs to invisible decays in vector boson fusion production

    Dominguez, Patricia Zoila
    A search for invisibly decaying Higgs bosons is performed using the vector boson fusion production (VBF) mode. This search was conducted using Run 2 data, collected by the CMS detector at the LHC in 2016 at a center of mass energy of 13 TeV, corresponding to an integrated luminosity of 5.9 fb-1. The control regions for the signal, invisibly decaying VBF Higgs bosons, are estimated using a cut-based selection strategy adapted from prior analyses. Selection criteria for the signal is applied as well. Assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the signal...

  12. Demonstrating visibly transparent solar cells and photodetectors

    Jungbluth, Anna, S.B. Massachusetts Institute of Technology
    The fabrication of inorganic semiconductor devices, such as silicon solar cells and photodetectors, is despite significant research still expensive and energy intensive. Especially for solar cells, high upfront costs are a limiting factor for large-scale fabrication and implementation. Organic semiconductors have attracted increasing attention over the last decade for their optoelectronic properties and potential applications in electronics and photonics. The ease of processing, light weight and low cost of organic semiconductors provides the opportunity for inexpensive, large-scale fabrication. In addition, the mechanical flexibility and bandgap tunability of organic materials enables the fabrication of flexible and semi-transparent organic solar cells and...

  13. Exploration of new methods for Lattice QCD

    Rios Tascon, Andres
    We explore two methods aimed at alleviating two difficulties in Lattice QCD: statistical noise and data storage. The first method intends to improve the signal-to-noise (S/N) ratio in three-point correlators, by extending previous work by Detmold and Endres. We test the method in the measurement of two observables: the nucleonic axial charge, and a matrix element computation related to the electromagnetic form factor of the rho meson. Only in the case of the rho we see a very slight improvement. We conclude that, in general, a case-by-case study would be needed to determine the effectiveness of the S/N optimization. The...

  14. Formalism for the rapid evolution of primordial black holes

    Russell, Megan, S.B. Massachusetts Institute of Technology
    This thesis presents two different formalisms which can be used together to evolve a density perturbation produced during inflation forwards in time in the radiation-dominated era of the early universe. The first formalism, based on early work by Misner and Sharp, is for the evolution of a perfect fluid in spherical symmetry under its own gravity. This allows us to efficiently determine if a black hole will form, but due to the formation of a singularity, it does not allow us to extract the black hole's mass. The second, new, formalism allows us to evolve the density perturbation past the...

  15. Jet substructure at the Large Hadron Collider

    Tripathee, Aashish
    In this thesis, we use the CMS Open Data to study the 2-prong substructure of jets. We use CMS's particle flow reconstruction algorithm to obtain jet constituents, which we then use to perform various jet substructure studies. After validating our basic kinematics and substructure results through a comparison to results from parton shower generators, we extract the 2-prong substructure of the leading jet using the soft drop algorithm. We find good agreement between the results from the Open Data and those obtained from parton shower generators. For the 2-prong substructure, we also compare to analytic calculations performed to modified leading-logarithmic...

  16. Lower bounds on the classical simulation of quantum circuits for quantum supremacy

    Dalzell, Alexander M
    Despite continued experimental progress, no task has yet been performed on quantum technology that could not also have been performed quickly on today's classical computers. One proposed path toward achieving this milestone, which is often referred to as quantum supremacy, is to perform specific types of quantum circuits for which it is guaranteed, under plausible complexity theoretic conjectures, that any classical approximate weak simulation algorithm for these circuits must take more than polynomial time. Instantaneous quantum (IQP) circuits and Quantum Approximate Optimization Algorithm (QAOA) circuits are examples of circuits with this guarantee under the assumption that the polynomial hierarchy (PH)...

  17. A statistical analysis of ambient noise monitored in the Arctic Ocean Basin

    Makris, Nicholas Constantine
    by Nicholas Constantine Makris.

  18. Double streaming at 35 AU during the coronal mass ejections of March 1991

    Nampaisarn, Thanasin V
    We analyze data associated with the coronal mass ejections of March 1991, with emphasis on a remarkable double-streaming proton event observed at 35 AU. The plasma data used in our analysis were collected by three spacecraft: Voyager 2 near 35 AU, Ulysses near 3 AU, and IMP-8 at 1 AU. The observations of the same CME events by three spacecraft over such a wide range of radii gives insight into the evolution of CMEs as they propagate from the Sun to 1 AU and then into the outer heliosphere. Of the many characteristics observed, we are especially interested in the...

  19. An investigation of the relevant parameters of an exponential pile

    Knapp, Richard William
    by Richard William Knapp.

  20. Radial equilibrium of toroidal plasmas.

    Pickrell, M. M. (Mark Manley)
    Thesis. 1976. B.S.--Massachusetts Institute of Technology. Dept. of Physics.

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