Academic Calendar

semester, 2014

Monday, January 20th 2014

Thursday, February 6th 2014
6:30 pm:
Van Vleck Lecture in 150 Tate Lab of Physics
Speaker: Don Gurnett, University of Iowa
Subject: The Epic Journey of Voyager 1 into Interstellar Space

After a journey of more than 36 years a spacecraft, Voyager 1, has for the first time crossed the heliopause into interstellar space. The heliopause is the long hypothesized boundary between the hot plasma envelope of the Sun (called the heliosphere) and the relatively cool interstellar plasma. The actual crossing is believed to have occurred at a heliospheric radial distance of 121 Astronomical Units in late August 2012, when a series of sharp increases in the cosmic ray intensities were observed, along with corresponding decreases in the solar energetic particle intensities. However, the plasma measurements needed to confirm the entry into the interstellar medium were not obtained until early the following April, as reported in the Sept. 27, 2013, issue of Science. For the first time we can now measure the unaltered intensity of galactic cosmic rays incident on the heliosphere, as well as other properties of the interstellar medium, such as the magnetic field. In this talk I will review some of the great achievements of the planetary phase of the Voyager mission, often called the “The Grand Tour of the Outer Planets,” and describe the long quest to reach the heliopause and cross into interstellar space.

Don Gurnett is the James A. Van Allen/Roy J. Carver Professor of Physics in the Department of Physics and Astronomy at the University of Iowa. He began his career in 1958 by working on the design of spacecraft electronics as an undergraduate engineer in James Van Allen’s cosmic ray research group shortly after Van Allen’s discovery of Earth’s radiation belts using Explorer 1, the first U.S. spacecraft. After receiving his B.S. in electrical engineering and his Ph.D. in physics at Iowa, he spent one year at Stanford University as a NASA trainee and then joined the Physics faculty at Iowa in 1965, where has been to the present time.

Over his career he led the development of instruments on more than 30 spacecraft projects, including many early Earth-orbiting spacecraft, and on several major planetary missions such as the famous Voyager 1 and 2 flights to the outer planets, the Galileo mission to Jupiter, and the Cassini mission to Saturn. His research primarily involves the study of radio emissions and waves that are generated in hot ionized gases, called plasmas, that occur in planetary magnetospheres and in the solar wind which is a hot ionized gas flowing outward from the Sun. These plasmas produce many different types of radio emissions and plasma waves that can provide crucial information on key properties of the plasma, such as the density and temperature, and even the rotation rate of the planet, as is the case for the outer planets. Over his career he has authored or co-authored over 600 scientific papers and has received numerous awards for his research and teaching. He has guided 62 graduate research projects and many of his students now hold prominent positions in space physics research.

Monday, March 17th 2014

Tuesday, March 18th 2014

Wednesday, March 19th 2014

Thursday, March 20th 2014

Friday, March 21st 2014

Wednesday, April 16th 2014
4:40 pm:
Senior Honors Thesis in 236A Physics
Speaker: Isaiah Gray, University of Minnesota
Subject: AC Magnetic Susceptibility in a Thin Film of Permalloy

Monday, April 21st 2014
4:40 pm:
Senior Honors Thesis in 236A Physics
Speaker: Ryan Frink, University of Minnesota
Subject: Superconducting fluctuations in the high-Tc cuprate superconductor LSCO

Wednesday, April 23rd 2014
4:40 pm:
Thesis Defense in 236A Physics
Speaker: Noah Trebesch, University of Minnesota
Subject: A Computational Method for Investigating Bifurcations in Oscillatory Biochemical Reaction Networks

Thursday, April 24th 2014
11:00 am:
Grand Opening Open House in Physics and Nanotechnology Building
Session I of the open house runs from 11 a.m.-2 p.m., Session II runs from 4-7 p.m.

Monday, April 28th 2014
4:40 pm:
Senior Honors Thesis in 236A Physics
Speaker: Yang Ge, University of Minnesota
Subject: X-ray Absorption Study of Doped Holes in High-Temperature Superconductor HgBa2Cu4+δ

Tuesday, April 29th 2014
2:00 pm:
Thesis Defense in 2-102 CMRR
Speaker: Jinjin Zhang, University of Minnesota
Subject: Development of frequency-modulated techniques for MRI of fast relaxing spins
This the public portion of Ms. Zhang's thesis defense.
3:35 pm:
Senior Honors Thesis in 236A Physics
Speaker: Tanner Lange, University of Minnesota
Subject: Z' Search in ATLAS eµ Events

Wednesday, April 30th 2014
4:40 pm:
Senior Honors Thesis in 236A Physics
Speaker: Johannes (Kevin) Nangoi, University of Minnesota
Subject: Photo-induced Conductance Changes in Composite nc-Ge/a-Si:H Thin Films

Thursday, May 1st 2014
5:30 pm:
Honor's Thesis in 110 PAN
Speaker: Matthew Epland, University of Minnesota
Subject: Simulation Studies of Proposed Upgrades to the ATLAS Detector Tracker

Friday, May 2nd 2014
09:00 am:
Thesis Defense in Physics 435
Speaker: Kyle Neary
Subject: Star Formation Histories of the Large and Small Magellanic Clouds
This is the public portion of Mr. Neary's PhD thesis defense

Tuesday, May 6th 2014
1:30 pm:
Speaker: Michael Veit, University of Minnesota
Subject: Transport Measurements in the Cuprate Superconductor HgBa2CuO4+δ
4:00 pm:
Senior Honors Thesis in 236A Physics
Speaker: Christopher Nolting, University of Minnesota
Subject: Fitting DARKexp predictions to dark matter halo profiles from simulation

Wednesday, May 7th 2014
4:40 pm:
Senior Honors Thesis in 236A Physics
Speaker: Max Veit, University of Minnesota
Subject: Stochastic Simulation of Genetic Regulatory Networks

Friday, May 9th 2014
12:00 pm:
Thesis Defense in 210 PAN
Speaker: Abe Reddy, University of Minnesota
Subject: Nonlocal Field Theories at Finite Temperature and Density.
This the public portion of Mr. Reddy's thesis defense.

Monday, May 12th 2014

Thursday, May 15th 2014
2:00 pm:
Thesis Defense in 110 PAN
Speaker: Derrick Toth, University of Minnesota
Subject: Measurement of non-DDbar decays of the psi(3770) resonance at BESIII
This is the public portion of Mr. Toth's defense.

The psi(3770) resonance is the first ccbar resonance above open-charm threshold and has a much larger width than the lower mass charmonium resonances. It is expected to decay predominantly to open-charm DDbar final states, with only a couple percent branching fraction to non-DDbar final states. However, inclusive branching fraction measurements of psi(3770) -> non-DDbar vary quite a bit, in a range from zero to fifteen percent. We present a measurement of the branching
ratio of e+e- -> psi(3770) -> non-DDbar hadrons at center-of-mass energy 3.773 GeV using data taken with the BESIII detectora as well as a measurement of the DDbar production cross section at this energy.

Friday, May 16th 2014
4:30 pm:
Congratulations Graduating Seniors!

Monday, May 19th 2014
1:00 pm:
Thesis Defense in 210 Physics
Speaker: Dan Endean, University of Minnesota
Subject: The Origin of Magnetic Noise in Square Nanoscale Magnetic Dots
This the public portion of Mr. Endean's thesis defense.

Friday, May 23rd 2014
09:00 am:
Thesis Defense in 435 Physics
Speaker: Jianjie Zhang, University of Minnesota
Subject: A Dark Matter Search Using the Final CDMS-II Data and 100 mm SuperCDMS Ge Detector Ionization Test
This the public portion of Mr. Zhang's thesis defenser

The data of the CDMS II final runs were reprocessed with improved charge reconstruction algorithm. The dark matter search result from a reanalysis of the data will be presented. As part of the development effort for the next generation SuperCDMS detectors, the ionization test of the 100 mm diameter germanium detectors will also be discussed.

3:00 pm:
Thesis Defense in PAN 120
Speaker: Aaron Smith, University of Minnesota
Subject: Ebert-Fastie Spectral Response Measurements and Simulation for EBEX Calibration
This is the public portion of Mr. Smith's defense.

I will be talking about simulations and measurements for an Ebert-Fastie Spectrometer and how they compare to one another. This involves use of reflective diffraction gratings and theoretical simulations of such gratings. This information is important as a calibration device for the EBEX CMB experiment.

Friday, May 30th 2014
12:00 pm:
Speaker: Hannes Hubmayr, NIST
Subject: Continuum polarimetry from the millimeter to the far-IR

Monday, June 2nd 2014
2:30 pm:
The School of Physics and Astronomy cordially invites you to a gathering to welcome our 2014 REU participants. Please stop by to say hello and enjoy some refreshments!

Friday, June 13th 2014

Monday, June 16th 2014

Tuesday, June 24th 2014
1:00 pm:
Thesis Defense in 210 Tate
Speaker: Chad Geppert, University of Minnesota
Subject: Electromotive force generated by spin accumulation in ferromagnet/n-GaAs heterostructures
This the public portion of Mr. Geppert's thesis defense.

Friday, July 4th 2014

Monday, July 7th 2014
2:00 pm:
Thesis Defense in PAN 110
Speaker: Chien-Te Wu, University of Minnesota
Subject: Proximity Effects in Ferromagnet/Superconductor Layered Heterostructures with Inhomogeneous Magnetization
This is the public portion of Mr. Wu's PhD thesis defense

Wednesday, July 9th 2014
1:30 pm:
Thesis Defense in 435 Physics
Speaker: Tianran Chen, University of Minnesota
Subject: Disorder Effects on Electron Transport in Nanocrystal Assemblies and Topological Insulators.
This the public portion of Ms. Chen's PhD thesis defense.

Friday, July 11th 2014

Monday, July 21st 2014
08:00 am:
NOvA Collaboration Meeting in various locations in Tate and PAN

Tuesday, July 22nd 2014
08:00 am:
NOvA Collaboration Meeting in various locations in Tate and PAN
10:00 am:
Academic Calendar in NHH 2-101 
Speaker: Jesse McCaffrey, Biochem, Molec Biol/Biophysics, University of Minnesota
Subject: Elucidating the Structural Dynamics of SERCA-PLB Regulation by Electron Paramagnetic Resonance
This is the Public Portion of Mr. McCaffrey's thesis defense

In muscle cells, contraction and relaxation are regulated by intracellular calcium, which is transported by the SR calcium ATPase (SERCA). In cardiac muscle cells, SERCA activity is inhibited by binding of phospholamban (PLB), though this inhibition is relieved by phosphorylation of PLB during adrenaline response. The mechanisms for this inhibition and relief of inhibition are unknown, so I use electron paramagnetic resonance (EPR) in conjunction with site-directed spin-labeling to study the structural dynamics of SERCA, PLB, and the SERCA-PLB complex. I will present results on SERCA and PLB homo/hetero-association, as well as orientation studies that help elucidate the SERCA-PLB interaction as affected by phosphorylation.

Wednesday, July 23rd 2014
08:00 am:
NOvA Collaboration Meeting in various locations in Tate and PAN

Thursday, July 24th 2014
08:00 am:
NOvA Collaboration Meeting in various locations in Tate and PAN

Friday, July 25th 2014
08:00 am:
NOvA Collaboration Meeting in various locations in Tate and PAN
11:00 am:
Speaker: Andrew W. Howard, Institute for Astronomy, University of Hawaii - Manoa
Subject: Earth-sized Exoplanets

The Kepler Mission has taught us that Earth-sized planets in the Habitable Zones of Sun-like stars are common and that many Earth-sized planets have rocky compositions. Three recent results highlight these remarkable properties of Earth-sized planets. First, our team measured the mass of the planet Kepler-78b, the first Earth-sized planet with a measured mass and radius outside of the Solar System. The bulk density of 5 grams per cubic centimeter suggests a rocky composition with an insubstantial atmosphere, similar to Earth. In a separate project, we showed that high densities are common for small exoplanets. Planets smaller than about 1.5 times Earth-size are mostly rocky, while thick gas atmospheres envelop most larger planets. Finally, our team estimated that 22 percent of Sun-like stars have a planet that is 1-2 times the size of Earth orbiting in the Habitable Zone. Warm, Earth-sized planets appear to be common.

Saturday, July 26th 2014
08:00 am:

Wednesday, August 6th 2014
09:00 am:
Please stop by and view Powerpoint presentations by the students in the 2014 REU program, poster session ends at 2:00 p.m.

Thursday, August 7th 2014
12:00 pm:
REU Poster Session in 110 PAN
Please stop by and view posters by the students in the 2014 REU program, poster session ends at 1:30 p.m.

Friday, August 8th 2014

Wednesday, August 13th 2014
2:00 pm:
Thesis Defense in 435 Physics
Speaker: Mike Schecter, University of Minnesota
Subject: Dynamics of Mobile Impurities in One-Dimensional Quantum Liquids

We study the dynamics of mobile impurities in a one-dimensional quantum liquid. Due to singular scattering with low-energy excitations of the host liquid, the impurity spectral properties become strongly renormalized even at weak coupling. This leads to universal phenomena with no higher-dimensional counterparts, such as lattice-free Bloch oscillations, power-law threshold behavior in the impurity spectral function and a quantum phase transition as the impurity mass exceeds a critical value. The additional possibility of integrability in one-dimension leads to the absence of thermal viscosity at special points in parameter space. The vanishing of the phonon-mediated Casimir interaction between separate impurities can be understood on the same footing.

We explore these remarkable phenomena by developing an effective low-energy theory that identifies the proper collective coordinates of the dressed impurity, and their coupling to the low-energy excitations of the host liquid. The main appeal of our approach lies in its ability to describe a dynamic response using effective parameters which obey exact thermodynamic relations. The latter may be extracted using powerful numerical or analytical techniques available in one-dimension, yielding asymptotically exact results for the low-energy impurity dynamics.

Friday, August 15th 2014
1:30 pm:
Thesis Defense in 110 PAN
Speaker: Kyle Zilic, University of Minnesota
Subject: Calibration and Design of the E and B EXperiment (EBEX) Cryogenic Receiver
This the public portion of Mr. Zilic's thesis defense.

Thursday, August 21st 2014
2:00 pm:
Thesis Defense in 435 Physics
Speaker: Sean Bartz, University of Minnesota
Subject: Meson Spectra from a Dynamical Three-Field Model of AdS/QCD
This is the public portion of Mr. Bartz's thesis defense.

Gauge/gravity dualities are tools that allow the analytic analysis of strongly-coupled gauge theories. The Anti-de Sitter Space/Conformal Field Theory conjecture posits a duality between ten-dimensional string theory and a super Yang-Mills theory. A phenomenologically-motivated modification of this correspondence is known as AdS/QCD, a duality between strongly-coupled QCD-like theories and weakly-coupled gravitational theories in an additional dimension. Quantum chromodynamics (QCD) is not scale-invariant, so the dual theory must be modified in the conformal dimension to reflect this.

I will discuss soft-wall models of AdS/QCD, wherein the conformal symmetry is broken by a field known as a dilaton. The dynamics of the dilaton and other background fields are examined, and a potential for these fields is determined. The background fields are numerically derived from this potential and used in the calculation of meson spectra, which match well to experiment.

Friday, August 22nd 2014

Monday, September 1st 2014

Tuesday, September 16th 2014
7:00 pm:
Misel Public Lecture in McNamara Alumni Center
Speaker: Andrei Linde, Stanford University
Subject: Universe or Multiverse?

Cosmological observations show that the universe is very uniform on the largest scales accessible to our telescopes, and the same laws of physics operate in all of its parts that we can see now. The best theoretical explanation of the uniformity of our world was provided by the theory of inflation, which was proposed about 30 years ago. Rather paradoxically, this theory also predicts that on a very large scale, much greater than what we can see now, the world may look totally different. Instead of being a single spherically symmetric balloon, our universe may look like a "multiverse", a collection of many different exponentially large balloons ("universes") with different laws of physics operating in each of them. In the beginning, this picture looked more like a piece of science fiction rather than a scientific theory. However, recent developments in inflationary cosmology, particle physics, and string theory provide strong evidence supporting the new cosmological paradigm. It changes our standard view of the origin and global structure of the universe and on our own place in the world.

Faculty Host: Keith Olive

Wednesday, September 17th 2014
10:30 am:
Thesis Defense in PAN 110
Speaker: Jeff Klein
Subject: Design, Implementation, and Calibration of Half-Wave Plate Polarimetry for the E and B Experiment
This is the public portion of Mr. Klein's thesis defense.

The E and B Experiment (EBEX) is a balloon-borne telescope designed to measure the polarization of the Cosmic Microwave Background (CMB) and dust foregrounds at 10' scales and three frequency bands of 150 GHz, 250 GHz, and 410 GHz in order to detect or constrain B-mode polarization. Results may provide evidence to support the theory of cosmological inflation, or constrain specific models.

EBEX's polarization measurement capability is implemented via continuously-rotating Half-Wave Plate (HWP) polarimetry. We discuss the design and implementation of the polarimetry hardware for the E and B Experiment (EBEX). In order to achieve low-temperature rotation of our 15 cm, 635 g achromatic HWP stack, we implement a unique application of a Superconducting Magnetic Bearing (SMB), building off an earlier prototype. We discuss design constraints, detail our implementation, and present results of tests of power dissipation, rotation speed stability, dynamic stability, and operational lifetime. We find power dissipation of 15 mW in our LDB configuration, and achieve successful operation of the system in both a 2009 test flight and a 2012 Long Duration (LDB) flight.

We design and carry out calibration tests to verify our ability to measure polarized signals. We develop a data analysis pipeline to extract polarization measurements from the chopped polarized signals we use in calibration; we verify and optimize the performance of this pipeline with a simulation. We find that a thorough understanding of the time constants of EBEX's bolometric sensors is essential to measure polarization. We develop methods to measure and remove the effects of these time constants. Tests of polarization rotation across our bands verify predictions of rotation due to our achromatic HWP 5-stack. Polarized beam scans allow us to set an absolute calibration for EBEX with a standard deviation of 1.5 degrees.

Tuesday, October 21st 2014
7:00 pm:
Café Scientifique in Bryant Lake Bowl
Speaker: Michel Janssen, University of Minnesota
Subject: Café Scientifique: Einstein: The Old Sage Versus Young Turk

Drawing on his work for the Einstein Papers Project and his collaborations with scholars at the Max Planck Institute for History of Science in Berlin, Michel Janssen will explain, in layperson's terms, the scientific methodology behind the spectacular successes of the young Einstein (special and general relativity and early contributions to quantum theory). He will then show how some of Einstein's personal experiences during World War I played a key role in making the older Einstein adopt a very different methodology, one no longer driven by empirical data but by mathematical elegance. This Café Scientifique promises to be an entertaining mix of history, philosophy, and physics.

Michel Janssen has long been interested in making the results of his research on the history and philosophy of modern physics accessible to a broader audience. A professor in the History of Science, Technology, and Medicine program at the University of Minnesota, Janssen has been offering a popular seminar called Einstein for Everyone. He is also one of the editors of The Cambridge Companion to Einstein, which likewise aims at a broad audience.

Cost of tickets is $5-12.

Thursday, October 30th 2014
11:20 am:
Thesis Defense in PaN 110
Speaker: Kevin Christie, University of Minnesota
Subject: Non-equilibrium spin accumulation in Co_2 Fe_x Mn_(1-x) Si/GaAs heterostructures
This is the public portion of Mr. Christie's thesis defense.

Tuesday, December 9th 2014
10:00 am:
Thesis Defense in 120 PAN
Speaker: Justin Hietala, University of Minnesota
Subject:  Ds Semileptonic Decays
This is the public portion of Mr. Hietala's Thesis Defense.

We measure six exclusive decay rates of the Ds meson using CLEO data gathered at a 4170 MeV center-of-mass energy.

Thursday, December 11th 2014
1:30 pm:
Thesis Defense in 130 PAN
Speaker: Tom Hofer, University of Minnesota
Subject: Development of CDMS-II Surface Event Rejection Techniques and Their Extensions to Lower Energy Thresholds
This is the public portion of Mr. Hofer's Thesis Defense.

The CDMS-II phase of the Cryogenic Dark Matter Search, a dark matter direct-detection experiment, was operated at the Soudan Underground Laboratory from 2003 to 2008. The full payload consisted of 30 ZIP detectors, totaling approximately 1.1 kg of Si and 4.8 kg of Ge, operated at temperatures of 50 mK. The ZIP detectors read out both ionization and phonon pulses from scatters within the crystals; channel segmentation and analysis of pulse timing parameters allowed eff ective fi ducialization of the crystal volumes and background rejection sufficient to set world-leading limits at the times of their publications.

A full re-analysis of the CDMS-II data was motivated by an improvement in the event reconstruction algorithms which improved the resolution of ionization energy and timing information. The Ge data were re-analyzed using three distinct background-rejection techniques; the Si data from runs 125 - 128 were analyzed for the fi rst time using the most successful of the techniques from the Ge re-analysis. The results of these analyses prompted a novel "mid-threshold" analysis, wherein energy thresholds were lowered but background rejection using phonon timing information was still maintained. This technique proved to have signifi cant discrimination power, maintaining adequate signal acceptance and minimizing background leakage.

The primary background for CDMS-II analyses comes from surface events, whose poor ionization collection make them difficult to distinguish from true nuclear recoil events. The novel detector technology of SuperCDMS, the successor to CDMS-II, uses interleaved electrodes to achieve full ionization collection for events occurring at the top and bottom detector surfaces. This, along with dual-sided ionization and phonon instrumentation, allows for excellent fi ducialization and relegates the surface-event rejection techniques of CDMS-II to a secondary level of background discrimination. Current and future SuperCDMS results hold great promise for mid- to low-mass WIMP-search results

Friday, December 12th 2014
Speaker: Agnes Mocsy, Pratt Institute
Subject: On Being a Woman in Physics: My Experiences Where the Sidewalk Ends
Talk is at 1 pm. Lunch (by reservation) is at 12:30

Please go to our eventbrite page to RSVP for this event.

Thursday, December 18th 2014
08:00 am:
09:30 am:
Thesis Defense in 120 PaN
Speaker: Scott Fallows, University of Minnesota
Subject: Measurement of Nuclear Recoils in the CDMS II Dark Matter Search
This is the public portion of Mr. Fallows Thesis Defense

The Cryogenic Dark Matter Search (CDMS) experiment is designed to
directly detect elastic scatters of weakly-interacting massive dark
matter particles (WIMPs), on target nuclei in semiconductor crystals
composed of Si and Ge. These scatters would occur very rarely, in an
overwhelming background composed primarily of electron recoils from
photons and electrons, as well as a smaller but non-negligible
background of WIMP-like nuclear recoils from neutrons, which must be
carefully limited. The CDMS II generation of detectors simultaneously
measure ionization and athermal phonon signals from each scatter, which
together allow effective discrimination against electron recoil
Nuclear recoils have suppressed ionization signals relative to electron
recoils of the same recoil energy. The overall normalization and
linearity of the energy scale for electron recoils in CDMS II detectors
is clearly established by peaks of known gamma energy in the ionization
spectrum of 133Ba calibration data. This electron-equivalent (keVee)
energy scale enables relative calibration of the total phonon signal by
enforcing unity yield for electron recoils, in aggregate. Subtracting an
event's Luke phonon contribution from its calibrated total phonon
energy, as measured by the ionization signal, results in a valid measure
of the true recoil energy (keVr) for both electron and nuclear recoils.
Systematic uncertainties affecting this energy scale for nuclear recoils
are presented, along with several methods to constrain their magnitude.
The resulting adjusted WIMP limits from CDMS II are presented.

Thursday, December 25th 2014

Friday, December 26th 2014

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