Academic Calendar

semester, 2016

Wednesday, January 6th 2016
10:00 am:
Thesis Defense in PAN 120
Speaker: Chen Hou, University of Minnesota
Subject: One-dimensional turbulence model of PRE bursts.
This is the public portion of Mr. Hou's thesis defense. His adviser is Alexander Heger.

A Type-I X-ray burst is the thermonuclear runaway that occurs on the surface of a neutron star in a binary system. Studies on these bursts are of great importance for understanding neutron stars, nuclear reactions and the equation of state of dense matter at low temperature. I will discuss a subset of X-ray bursts, photospheric radius expansion (PRE) bursts, that is powerful to lift up the photosphere of the star with the simulations based on a new 1D turbulence model, ODT. The model is different in that the turbulent motion is implemented according to a stochastic process and an eddy event is represented by a measure-preserving map. I will compare the light curve and turbulent motion development with a KEPLER model in which the traditional mixing length theory is applied.

Monday, January 18th 2016

Wednesday, January 20th 2016
3:00 pm:
Thesis Defense in 337 Amundson Hall
Speaker: Gaurav Shukla, University of Minnesota
Subject: Thermoelastic properties of iron- and aluminum-bearing bridgmanite at high pressures and temperatures
This is the public portion of Mr. Shukla's thesis defense. His adviser is Renata Wentzcovitch, CEMS

Thursday, January 21st 2016
10:00 am:
Thesis Defense in 334 PAN
Speaker: Semere Tadesse, University of Minnesota
Subject: "Nano-Optomechanical System based on Microwave Frequency Surface Acoustic Waves"
This is the pulbic portion of Mr. Tadesse's thesis defense. His advisor is Mo Li, ECE

Cavity optomechnics studies interaction of cavity confined photons with nanomechanical motion. Many of the studies reported so far are focused on interaction of photons with localized mechanical modes. In my doctoral research, I did experimental investigations to extend this study to propagating phonons. We used surface travelling acoustic wave as mechanical element of the optomechanical system. The system constitutes microwave frequency surface acoustic wave transducers co-intergrated with optical cavities on piezoelectric aluminum nitride film. Acousto-optic modulation with the acoustic wavelength significantly below the optical wavelength and modulation speed over 10GHz was demonstrated. The phase and modal matching conditions in this paradigm were investigated for efficient optmechanical coupling. This system was used to demonstrate optomecahnically induced transparency and absorption, which are dynamical consequences of the optomechanical coupling. Phase coherent interaction of the acoustic wave with multiple nanocavities was also explored, highlighting the scalability of the optomechanical system. In a related experiment, a photonic nanoscavity was placed inside an acoustic echo-chamber, and interaction of a phonon pulse with the photonic cavity was investigated. One limitation of our system is that the surface generated acoustic wave leaks into the supporting silicon substrate depriving the optical cavities the strain field necessary for strong optomechanical coupling. This limitation was addressed by realizing the optomechanical system on suspended aluminum nitride membrane. The membrane confines both the acoustic and optical fields and led to a strong optmechanical coupling.

Friday, March 18th 2016

Thursday, March 24th 2016
2:00 pm:
Thesis Defense in PAN 210
Speaker: Dominick Rocco, University of Minnesota
Subject: Muon Neutrino Disappearance in NOvA with a Deep Convolutional Neural Network Classifier
This is the public portion of Mr. Rocco's thesis defense.

The NuMI Off-axis Neutrino Experiment (NOvA) is designed to study neutrino oscillation in the NuMI beam. Neutrinos at the Main Injector (NuMI) is currently being upgraded to provide 700 kW. NOvA observes neutrino oscillation using two detectors separated by a baseline of 810 km; a 14 kt Far Detector in Ash River, MN and a func- tionally identical 0.3 kt Near Detector at Fermilab. The experiment aims to provide new measurements of ∆m232 and θ23 and has potential to determine the neutrino mass hierarchy as well as observe CP violation in the neutrino sector. Essential to these analyses is the classification of neutrino interaction events in NOvA detectors. Raw detector output from NOvA is interpretable as a pair of images which provide orthogonal views of particle interactions. A recent advance in the field of computer vision is the advent of convolutional neural networks, which have delivered top results in the latest image recognition contests. This work presents a novel approach particle physics analysis in which a convolutional neural network is used for classification of particle interactions. The approach has been demonstrated to improve the signal efficiency and purity of the event selection, and thus physics sensitivity. Early NOvA data has been analyzed (2.74×1020 POT, 14 kt equivalent) to provide new best-fit measurements of sin2(θ23) and |∆m232|.

Tuesday, April 12th 2016
1:30 pm:
Thesis Defense in 130 PAN
Speaker: Nicholas Raddatz, University of Minnesota
Subject: Muon Neutrino Disappearance in NOvA
This is the public portion of Mr. Raddatz's thesis defense. His adviser is Dan Cronin-Henessy

Monday, April 25th 2016
10:30 am:
Thesis Defense in 142 WBOB
Speaker: Ivan Gordeli, University of Minnesota
Subject: Singlet Glueballs in Klebanov-Strassler Theory
This is the public portion of Mr. Gordeli's thesis defense. His advisor is Arkady Vainshtein.

Thursday, April 28th 2016
10:00 am:
Thesis Defense in Civil Engineering 213
Speaker: Charles McEachern, University of Minnesota
Subject: Field Line Resonance in "Tuna Half" Dimensions
This is the public portion of Mr. McEachern's thesis defense. His advisor is Bob Lysak.

Friday, May 6th 2016
Last day of instruction before final exams.
2:30 pm:
Poster Session in PAN Lobby
Students in Phys 4052 will present their class projects.
4:00 pm:
Henry Erikson Lecturer in 101 Fraser Hall
Speaker: Dr. Jay Marx, Senior Advisor, LIGO Laboratory, California Institute of Technology
Subject: The Discovery of Gravitational Waves from Merging Black Holes

On February 11, 2016 headlines announced the discovery of gravitational waves from a merging pair of black holes 1.3 billion light years away, confirming the most radical prediction of Einstein’s theory of gravity. What is this all about? What are gravitational waves? Why is it so important?

This discovery was made by LIGO using instruments spanning miles and yet capable of measuring distances with an accuracy of one billionth the size of an atom, among the most precise instruments ever constructed. LIGO now involves about 1000 scientists and engineers from 80 universities in 16 countries around the world, including the University of Minnesota.

This talk will explain the excitement, what the discovery means, how it was made and why it will open a new window on the universe. The presentation will be aimed at non-scientists with many videos and photos and no equations or jargon.

Friday, May 13th 2016
Students staff and faculty are invited to join the celebration.

Monday, May 23rd 2016

Friday, May 27th 2016
3:30 pm:
Thesis Defense in 142 WBOB
Speaker: Jin Chen, University of Minnesota
This is the public portion of Jin Chen's thesis defense. Chen's advisor is Arkady Vainshtein.

Monday, May 30th 2016

Friday, June 10th 2016
08:00 am:

Monday, June 13th 2016

Monday, July 4th 2016

Friday, July 22nd 2016
12:00 pm:
Thesis Defense in PAN 110
Speaker: Adam Peterson, University of Minnesota
Subject: Low energy dynamics of non-perturbative structures in high energy and condensed matter systems
This is the public portion of Mr. Peterson's thesis defense.

This dissertation presents some results on the application of low energy effective field theory vortex dynamics in condensed matter and materials systems. For the first half of the presentation we discuss the possibility of non-Abelian gapless excitations appearing on U(1)- vortices in the B phase of superfluid ^3 He. Specifically, we focus on superfluid ^3 He-like systems with an enhanced SO(3)L- rotational symmetry allowing for non-Abelian excitations to exist in the gapless spectrum of vortices. We consider a variety of vortices in the B-phase with different levels of symmetry breaking in the vortex core, and show conditions on the phenomenological parameters for certain vortices to be stable in the bulk. We then proceed to develope the low energy effective field theory of the various vortex types and consider the quantization of excitations. The process of quantization leads to interesting surprises due to non-lorentz symmetry that are not typically encountered in the analogous cases of U(1)×SU(N)- gauge models discussed in high energy theory.

The second half of this dissertation focuses on two types of vortices that appear in a particular model that is a modification of the well known Abelian-Higgs model. The specific modification includes a vector spin field in addition to the U(1)- Higgs field and gauge fields of the original model. The particular form of the lagrangian results in a cholesteric vacuum structure, with interesting consequences for the vortices in the model. We observe the effects of such a modification on the well known U(1)- vortex appearing in the original model due to the emergent spin field in the vortex core. We also consider a new type of vortex that is most closely related to a spin vortex. This vortex appears due to the topology introduced by the new spin field. The low energy effective field theory is also investigated for this type of vortex.

Saturday, July 30th 2016
8:30 pm:
Universe in the Park in Gooseberry Falls State park
Summer telescope observing program at local state parks. Contact: for more info.

Friday, August 5th 2016
10:00 am:
Theis Defense in 142 WBOB
Speaker: Marcos Garcia, University of Minnesota
Subject: No-scale inflation
This is the public portion of Mr. Garcia's thesis defense. HIs adviser is Keith Olive.
1:00 pm:
Thesis Defense in PAN 110
Speaker: Barry Costanzi, University of Minnesota
Subject: Emergent 1/f noise in systems of oscillating nanomagnetic dots
This is the public portion of Mr. Costanzi's thesis defense. His adviser is Dan Dahlberg.
8:30 pm:
Universe in the Park in Father Hennepin State Park
Summer telescope observing program at local state parks. Contact: for more info.

Saturday, August 6th 2016
8:30 pm:
Universe in the Park in Mille Lacs Kathio State Park
Summer telescope observing program at local state parks. Contact: for more info.

Friday, August 12th 2016
8:30 pm:
Universe in the Park in Lake Maria State Park
Summer telescope observing program at local state parks. Contact: for more info.

Saturday, August 13th 2016
8:30 pm:
Universe in the Park in William O'Brien State Park
Summer telescope observing program at local state parks. Contact: for more info.

Thursday, August 25th 2016
09:00 am:
CSE at the Minnesota State Fair in Minnesota State Fairgrounds

Friday, August 26th 2016
1:00 pm:
Thesis Defense in PAN 120
Speaker: Terry Bretz-Sullivan, University of Minnesota
Subject: Transport in ionic liquid gated and superconducting nanostructures
This is the public portion of Mr. Bretz-Sullivan's thesis defense. His advisor is Allen Goldman.

Monday, September 5th 2016

Tuesday, September 27th 2016
3:00 pm:
Thesis Defense in Vincent Hall 364
Speaker: Jared Turkewitz, University of Minnesota
Subject: Measurement of the associated production of a Z boson with a J/psi meson with the CMS experiment at a center-of-mass energy of 8 TeV
This is the public portion of Mr. Turkewitz's thesis defense.

The associated production of a Z boson and a J/ψ meson provides information about the production mechanisms of quarkonium. A measurement of the associated production of a Z boson, which decays to leptons, and a J/ψ meson, which decays to muons, relative to the inclusive production of a Z boson, which decays to leptons, is presented. The measurement was made using the full 19.7 fb−1 of proton-proton collision data collected at a center-of-mass energy of √s = 8 TeV by the Compact Muon Solenoid detector at the Large Hadron Collider.

Saturday, October 8th 2016
12:00 pm:
SPA Fall Picnic in Boom Island Park Shelter

All SPA faculty, staff, postdocs, students, and their families are welcome to attend! We ask that everyone who comes either bring a dish to share or contribute $5 towards the cost of the event. Monetary contributions can be dropped off with a GradPhi officer or in any of the physics offices (with Jenny in 250 PAN, Amanda in Williamson, Angie in McNamara, Meghan in WBOB).

Please RSVP if you plan on coming to help us get everything organized.

If you're planning on bringing a side dish or dessert to share, please let us know what you will be bringing on the form.

Thursday, October 13th 2016
3:15 pm:
Group Photo in Civil Engineering Building Courtyard
Refreshments will be served in PAN Lobby prior to group photo. Come get a cookie and then have your picture taken with the group.

Wednesday, October 19th 2016
7:00 pm:
Eleventh Annual Misel Lecture in McNamara Alumni Center
Speaker: John Preskill, California Institute of Technology
Subject: Quantum Computing and the Entanglement Frontier

The quantum laws governing atoms and other tiny objects seem to defy common sense, and information encoded in quantum systems has weird properties that baffle our feeble human minds. John Preskill will explain why he loves quantum entanglement, the elusive feature making quantum information fundamentally different from information in the macroscopic world. By exploiting quantum entanglement, quantum computers should be able to solve otherwise intractable problems, with far-reaching applications to cryptology, materials, and fundamental physical science. Preskill is less weird than a quantum computer, and easier to understand.

Wednesday, October 26th 2016
12:00 pm:

Please bring a baked goods plate--or--bag to donate for sale on October 26th, as well as buy a plate from the selection. Donations are also appreciated.

More information about the SPA Community Fund Drive can be found on the website

Thursday, November 3rd 2016
11:30 am:
Time to apply for a major? Consider Physics!

Over a FREE Pizza Lunch there will be former physics majors talking about their current jobs and the array of careers you can pursue with a physics degree. There will also be lab tours and a panel of current Physics majors to answer questions.

Daytime Session
11:30 a.m. - 2:20 p.m., 110 Physics & Nanotech Bldg (PAN)

Can’t make it during the day?
There will be additional lab tours at 6:00 p.m. leaving from the PAN lobby.

Thursday, November 10th 2016
10:00 am:
Thesis Defense in PAN 130
Speaker: Changjiang Liu, University of Minnesota
Subject: Dynamic Detection of Spin Accumulation by Ferromagnetic Resonance
This is the public portion of Mr. Liu's thesis defense.

Thursday, November 24th 2016

Friday, November 25th 2016

Monday, December 12th 2016
08:30 am:
Thesis Defense in Appleby Hall, Room 319
Speaker: Mark Pepin, University of Minnesota
Subject:  Low-Mass Dark Matter Search Results for the Cryogenic Dark Matter Search
This is the public portion of Mr. Pepin's thesis defense. His advisor is Priscilla Cushman.

An ever-increasing amount of evidence suggests that approximately one quarter of the energy in the universe is composed of some non-luminous, and hitherto unknown, "dark matter." Lower-mass dark matter has become more prominent in the past few years. The Cryogenic Dark Matter Search (CDMS) detectors can be operated in an alternative, higher-biased mode, to decrease their energy thresholds and correspondingly increase their sensitivity to low-mass WIMPs. This is the CDMS low ionization threshold experiment (CDMSlite), which has pushed the frontier at lower masses. This dissertation describes the second run of CDMSlite at Soudan: its hardware, operations, analysis, and results. The results include new WIMP mass-cross section upper limits on the spin-independent and spin-dependent WIMP-nucleon interactions. Thanks to the low background and threshold, these limits are the most sensitive in the world below WIMP masses of ~4 GeV/c^2. This also demonstrates the great promise and utility of the high-voltage operating mode in the future SuperCDMS SNOLAB experiment.

Tuesday, December 13th 2016

Hayden McCormick, "Experimental Analysis of Oscillating Guitar Strings using High Speed Photography."

Prashant Dhakal & Jack Goodsell, "The Effect of Lateral Retention Forces of Water on a Plexiglass Surface."

Vandon Duong, "Quantitative Characterization of RF Coils Designed for Human Ultrahigh Field MRI"

Alex Luna & Garrett Marxen, "The Effect of Static Magnetic Field on the Viscosity of Ferrofluid"

Dawson Kimyon, "Pulsed NMR Spectroscopy"

Jake Royal, "Development of a Variable Spectral- Width Wavelength Tunable Laser Using a Superluminescent Diode."

Thursday, December 15th 2016
2:00 pm:
Thesis Defense in PAN 110
Speaker: Brent Perreault, University of Minnesota
Subject: Identifying a Kitaev spin liquid
This is the public portion of Mr. Perreault's thesis defense. His advisor is Fiona Burnell.

The search for quantum spin liquid physics has been long and storied, but RuCl3 and the iridates A2IrO3 have opened up the possibility of realizing a new family of "Kitaev" quantum spin liquids. The Kitaev honeycomb model is a highly anisotropic quadratic spin model that has an exact QSL ground state. We study the Kitaev model on a variety of 3D lattices with the goal of identifying characteristic signatures of its QSL phase. We use the exact solution to demonstrate several features of the Kitaev QSL both quantitative and qualitative. These include broad Raman spectra characteristic of the fractionalized excitations and rich momentum-dependent RIXS spectra. We discuss how these measurements can probe novel features of these QSL's. For example, topological surface modes accessible to Brillouin scattering, and Landau level peaks in Raman spectra on carefully strained honeycomb fakes. In addition, the technical underpinnings of these calculations are reviewed in detail. Specifically, the theoretical predictions are completed with considerations of the e ects of perturbations, finite temperature studies, and careful analysis of the experimental excitations.

Friday, December 16th 2016
11:15 am:
Thesis Defense in Akerman Hall 313
Speaker: Alberto Hinojosa Alvarado, University of Minnesota
Subject: Time-reversal symmetry breaking superconductivity in the coexistence phase with magnetism in Fe pnictides
This the public portion of Mr. Alvarado's thesis defense. His advisor is Andrey Chubukov.

I argue that superconductivity in the coexistence region with spin-density-wave (SDW) order in weakly doped Fe pnictides differs qualitatively from the ordinary s+− state outside the coexistence region as it develops an additional gap component which is a mixture of intrapocket singlet (s++) and interpocket spin-triplet pairings (the t state). The coupling constant for the t channel is proportional to the SDW order and involves interactions that do not contribute to superconductivity outside of the SDW region. I argue that the s+− and t-type superconducting orders coexist at low temperatures, and the relative phase between the two is, in general, different from 0 or π, manifesting explicitly the breaking of the time-reversal symmetry promoted by long-range SDW order.

2:00 pm:
Thesis Defense in Room 162 Amundson Hall
Speaker: Yanjun Yang, University of Minnesota
Subject: An Attempt to Synthesize Mn-doped Pyrite Thin Films
This is the public portion of Mr. Yang's Masters Thesis Defense. His advisors are Prof. Chris Leighton, Prof. Eray S. Aydil

Solar energy is a good choice to meet the energy and environmental challenges nowadays. Researchers have been searching for materials to make a solar absorber which can be widely applied in inexpensive photovoltaic devices. Pyrite FeS2 has long been recognized as a potential candidate for its theoretical high efficiency, low cost, earth-abundance and non-toxicity. However, the performance of pyrite based solar cells has been limited for some unknown reasons since the mid-1980s. The poorly understood doping mechanisms might be a reason for this low efficiency. Identifying unknown dopants, however, remains a big challenge, as does controlled n and p doping. In this work, we explore an approach to study doping by intentionally introducing Mn into pyrite thin films, which we may produce a p-type pyrite thin film. We focus on p-type films because unintentionally doped films were recently shown to be n-type, likely due to S vacancies. Development of a p dopant would therefore enable p-n junctions, a key step in creating a pyrite based solar absorber. In this work, we synthesized and studied the chemical, structural and electronic transport properties of Mn-doped pyrite thin films via ex situ sulfidation.

Monday, December 19th 2016
08:00 am:

Tuesday, December 20th 2016
08:00 am:

Wednesday, December 21st 2016
08:00 am:

Thursday, December 22nd 2016
08:00 am:

Friday, December 23rd 2016

Monday, December 26th 2016

Thursday, December 29th 2016
2:00 pm:
Thesis Defense in M10 library, Mesonic Memorial Building
Speaker: Pamela Sooriyan, University of Minnesota
Subject: Dose enhancement in bone due to the 16O(γ,n)15O reaction
This is the public portion of Ms. Sooriyan's thesis defense. Her thesis advisor is John Broadhurst.

External beam radiation therapy is the most common option in the treatment of malignant tumors. It mainly uses Bremsstrahlung photons produced when highly accelerated electrons are incident on a target of high atomic number, gamma rays produced by radionuclides, and electrons beams. In the mega-voltage range of photon beams, the dose absorbed by the tumor is primarily by the incident photons losing their energy to the tissues of the tumor by Compton scattering and pair production. Enhancing photonuclear disintegrations offers the possibility of increasing the dose to the tumor (for the same delivered dose) by introducing secondary charged particles in the irradiated region.
The dose delivered by secondary charged particles from the 16O(γ,n)15O reaction in bone was measured in an attempt to explore the feasibility of local dose enhancement due to photo nuclear disintegrations.

For an externally delivered dose of 13 Gray, the additional dose due to positrons was measured to be 0.18 mGray in bone and 0.025 mGray in tissue, using a photon beam that had about 1.3% of photons of energy needed to initiate the 16O(γ,n)15O reaction.

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