Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1999. / Includes bibliographical references (p. 412-417). / Measurements of [pi]+ , K+ , K-, and p production from Au - Au reactions have been made by experiments E866 and E917 at the Brookhaven National Laboratory Alternating Gradient Synchrotron. The measurements have been made as a function of beam energy, at kinetic beam energies in the laboratory of 2 and 4 A· Ge V, by experiment E866, and of 6 and 8 A-GeV, by experiment E917. The data has been divided into event classes, based on the total multiplicity in an event. The particles were measured in an angular range from 14 to 57° . Within a range of rapidity Y - Ynn l < 0.25Ynn, and within the upper 339 mb in total multiplicity, the yields of all produced particles increase as the beam energy increases. The yields of Kincrease more rapidly with beam energy than those of the K+ , and those of the K+ increase more rapidly with beam energy than those of the [pi]+ . The (m.1 - mo) of the particles also increase as the beam energy increases, but not as rapidly as the yields. The ratio of the yields, K+ /[pi]+ , within this range of rapidity increases steadily from ... The K- / K+ ratio within this range of rapidity, in the upper 339 mb of total multiplicity, increases steadily from 8% at 4 A· GeVto 19% at 10.8 A· GeV. The K- / K+ ratio is constant as a function of centrality at all beam energies and rapidities measured. It is not constant with rapidity. The production of kaons therefore shows a clear consistency across all beam energies in the range measured in this thesis. Hadronic models cannot reproduce the dN /dY of K+ at all beam energies at this stage of their development. At an equal distance from the p - p production threshold, the K- yield is lower by a factor of 5 than than tl1e K+ yield. This stands in contrast to the value of 1.0±0.4 measured by the K aoS collaboration ... / by James Colville Dunlop. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2006. / Includes bibliographical references (p. 183-197). / In this thesis we will explore three approaches to aspects of the fundamental structure of string theory. We first provide a brief review of perturbative string theory, and briefly discuss how each of the three topics to be discussed in the body of this thesis depart from this starting point. We then study the open string one-loop tadpole diagram in Witten cubic open string field theory. We compute this diagram both analytically and numerically and study the divergences arising from the collective behavior of open string fields in the short-distance region of the diagram. We demonstrate that this region of the diagram encodes information about the linearized Einstein equation describing the shift in the closed string fields in reaction to the D-brane supporting the open strings. We also show that the manner in which this information is encoded is somewhat singular, and comment on the implications for the quantum consistency of open bosonic string field theory. We next compute the closed string radiation from a decaying D-brane in type II string theory. The calculation is made possible by noting that the integrals involved in the requisite disk one-point functions reduce to integrals over the group manifold of a product of unitary groups. / (cont.) We find that the total number and energy of strings radiated during the decay process diverges for D-branes of small enough dimension, in precise analogy to the bosonic case. Finally, we investigate a simple class of type II string compactifications which incorporate nongeometric "fluxes" in addition to "geometric flux" and the usual H-field and R-R fluxes. We develop T-duality rules for NS-NS geometric and nongeometric fluxes, which we use to construct a superpotential for the dimensionally reduced four-dimensional theory. The resulting structure is invariant under T-duality, so that the distribution of vacua in the IIA and IIB theories is identical when nongeometric fluxes are included. / by Jessie (Julia) Shelton. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1964. / Vita. / Includes bibliographical references (leaves 92-94). / by Douglas Murray Sheppard. / Ph.D.

Thesis: S.M., Massachusetts Institute of Technology, Department of Physics, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 151-155). / 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 waves from the mergers of compact objects out to hundreds of Mpc. Finding the electromagnetic counterparts to gravitational-wave sources, which may appear as kilonovae events, will give far greater insight into these mergers. While the Large Synoptic Survey Telescope will be a capable facility for following up triggers from gravitational-wave observatories at [lambda] < [mu]m, a wide-field infrared telescope operating at [lambda] > [mu]m would complement its capabilities. In this Thesis, I first describe a simulation of the TESS mission. The simulation predicts TESS should find hundreds of small transiting planets; those with the brightest host stars will be favorable for radial-velocity determinations of their masses and spectrophotometric measurements of their atmospheres. However, approximately half of the transit-like signals that TESS detects will turn out to be astrophysical false-positives arising from stellar eclipsing binaries. I will discuss how planets can be distinguished from eclipsing binaries using the TESS data and a ground-based follow-up campaign. Secondly, I describe the development of InGaAs detectors for near-IR imaging and photometry. These detectors are a less-expensive alternative to the HgCdTe detectors in current use, enabling wide-area IR surveys and IR observations with small telescopes to take place. Using camera hardware that I designed and constructed, I have tested InGaAs detectors as they have matured into an appropriate technology for near-IR time-domain astronomy. I will discuss their possible use for following up the TESS detections and gravitational-wave triggers. / by Peter William Sullivan. / S.M.

Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2003. / Cataloged from PDF version of thesis. / Includes bibliographical references (page 41). / 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 determining a shape and pole solution for (1289) Kutaïssi. / by Alison J. Klesman. / S.B.

Thesis (Ph.D.) Massachusetts Institute of Technology. Dept. of Physics, 1956. / Bibliography: leaves 30-31. / by Burton Richter. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1996. / Includes bibliographical references (p. 151-153). / by Christopher B. Moore. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1986. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographies. / by Phillip Lloyd Gould. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1987. / The bracketed information is an arrow pointing to the right on the title page. / Bibliography: leaves 60-63. / by Mourad Dhina. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Physics, 2004. / Includes bibliographical references (p. 77-83). / In this thesis, I discuss observations of the optical afterglows of seven HETE GRBs, carried out mainly with the Magellan Telescopes at Las Campanas Observatory in Chile. Five of the bursts, GRBs 020331, 030115, 030418, 030723, and 030725, had optical afterglows. I was able to make detections of all but GRB 030115. GRBs 011212 and 020531 did not have observed afterglows, and with 030115, I can place constraining upperlimits on their optical or near infrared afterglows. For the bursts which were detected, I have constructed light curves from my data and that available from the literature in order to study the nature of these afterglows and compare them to the available theoretical models. / by Allyn Dullighan. / S.M.