Probing the Accelerating Universe with the Dark Energy Survey UF Physics Colloquium Physics Home

PHYSICS COLLOQUIUM SCHEDULE
Fall 2017

The Colloquia are in Room 1002 NPB on Thursday at 4:05 PM
Refreshments will be served starting at 3:15 PM in NPB 2205

Contact: A. Hebard afh@phys.ufl.edu)
Department of Physics Colloquium Committee:
Hebard (Chair), Fry, Furic, Mitselmakher, Obukhov, Ramond (members)


AUGUST 24

  Speaker Graduate Student Meeting with Dr. Xiaoguang Zhang 4:00pm in 1002 NPB

August 31

  Speaker Amlan Biswas, UF Physics
  Title Magnetoelectrism in crystals
  Abstract A discussion of the magnetic properties of matter usually addresses the effect of magnetic fields on magnetization. While the effect of an electric field on magnetism is also firmly established, we are much more familiar with the equation M = χmH than with M=αE, where χm is the magnetic susceptibility and α quantifies the magnetoelectric effect. A reason for this unfamiliarity is that α is negligible for most magnetic materials. I will discuss the origin of the magnetoelectric effect in materials and why the effect is small in single phase materials. I will describe our experiments on three materials from the perovskite family: LaPrCaMnO3, BiMnO3, and SrTiO3 and the unexpectedly large magnetoelectric coupling we observed under certain conditions. Ongoing experiments in our research group have been designed to fabricate and study these materials and further enhance their magnetoelectric properties.
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SEPTEMBER 7

  Speaker James Hamlin, UF Physics
  Title The expanding role of compressed matter in superconductivity research
  Abstract Measurements at low temperature are a standard part of the characterization of newly discovered materials. Due to their technical difficulty, measurements under high pressure conditions are not nearly as ubiquitous. Consequently, the vast majority of materials have yet to be characterized under pressure. The recent discoveries of high-temperature superconductivity in compressed iron selenide and hydrogen sulfide hint that many exciting discoveries still await in the unexplored high-pressure phases of otherwise well-studied materials. In this talk, I will provide an overview of results obtained using a new apparatus that combines designer diamond anvils with automated pressure measurement and application in order to to rapidly locate and characterize pressure induced phase transitions. Using elemental barium metal as an example, I will also present work using this apparatus to examine superconductivity in metastable structures obtainable only by varying pressure under cryogenic conditions. Finally, I will discuss an ongoing collaborative effort which combines synthesis, high pressure measurements, and high-throughput computation with the aim of accelerating the discovery of pressure-induced superconductors.
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SEPTEMBER 14

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SEPTEMBER 21

  Speaker Tim Sumner (Imperial College)
  Title Celestial Dynamics: The Mystery Deepens
  Abstract The mid-1980s saw the birth of many dedicated direct dark matter search experiments, starting up as a result of the mounting evidence for enhanced gravitational potentials in a number of astrophysical systems, and in the light of many particle-physics frameworks predicting new (suitable) particles. These experiments and indeed many other indirect search experiments have made solid progress since then but still we lack any definitive evidence. Meanwhile there has been interesting growth in alternative gravity scenarios, but also leaving us without a clear solution. This talk will review the situation and look forward to what the future might hold with new experiments and new types of observation.
Host Mueller

SEPTEMBER 28

  Speaker Klaus Honscheid, The Ohio State University
  Title Probing the Accelerating Universe with the Dark Energy Survey
  Abstract Why is the expansion of the universe speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If itís due to dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? To address these questions, the Dark Energy Survey (DES) collaboration built the 570-megapixel Dark Energy Camera for the Blanco 4-meter telescope at NOAO's Cerro Tololo Inter-American Observatory in Chile, to carry out a 5-year, deep, multi-band, optical survey of several hundred million galaxies and several thousand supernovae. The DES survey began in 2013 and recently started the fifth and final observing season. In this talk I will highlight recent results and discuss how DES is measuring the history of cosmic expansion and the growth of structure using complementary techniques including the large-scale galaxy distribution and weak gravitational lensing of the light emitted by 26 million distant galaxies.
Host Darin Acosta

OCTOBER 5

  Speaker Vivien Zapf, NHMFL
Title TBD
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Host Art Hebard

OCTOBER 12

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OCTOBER 19

  Speaker Chris Lobb (University of Maryland)
  Title Ohmís Law and Beyond for Atom Circuits
  Abstract Atomtronics is an emerging interdisciplinary field that is creating new devices and circuits where ultracold atoms, often in the superfluid state, have a role analogous to that of electrons in electronics. After giving a brief overview of some experimental neutral atom-circuit results, I will show how these results can be described by lumped-element models analogous to those used in electronics. Resistance, capacitance and inductance can be defined for neutral-atom circuits, and they are analogous to the Sharvin resistance (in the non-superfluid case), quantum capacitance, and kinetic inductance, respectively, in electronic circuits. In the superfluid case, quantum coherence leads to behavior analogous to superconducting quantum interference devices (SQUIDs) and vortex-induced resistance. In collaboration with R. B. Blakestad, G. K. Campbell, C. W. Clark, S. Eckel, M. Edwards, K. Helmerson, W. T. Hill, III, F. Jendrzejewski, J. G. Lee, B. J. McIlvain, S. R. Muniz, N. Murray, W. D. Phillips, A. Ramanathan, K. C. Wright, and M. Zelan.
Host Art Hebard

OCTOBER 26

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NOVEMBER 2

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NOVEMBER 9

  Speaker Shane Larson (U. Chicago)
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Host Guido Mueller

NOVEMBER 16

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NOVEMBER 30

  Speaker Robert Brandenberger, McGill University
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Host Richard Woodard



PHYSICS COLLOQUIUM SCHEDULE

Spring 2018

The Colloquia are in Room 1002 NPB on Thursday at 4:05 PM
Refreshments will be served starting at 3:15 PM in NPB 2205

Contact: A. Hebard afh@phys.ufl.edu)
Department of Physics Colloquium Committee:
Hebard (Chair), Fry, Furic, Mitselmakher, Obukhov, Ramond (members)

JANUARY 4

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JANUARY 11

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JANUARY 18

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JANUARY 25

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FEBRUARY 1

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FEBRUARY 8

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FEBRUARY 15

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FEBRUARY 22

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MARCH 1

  Speaker Spring Break
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MARCH 8

  Speaker APS meeting
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MARCH 15

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March 22

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March 29

  Speaker Barry Barish, Caltech
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  Host Guenakh Mitselmakher

April 5

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APRIL 12

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APRIL 19

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