Student Research Symposium - Department of Physics & Astronomy ...

Student Research Symposium
August 13, 2011
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Contents
Abstracts ......................................................................................... 3
Poster Session Abstracts ................................................................ 12
Participants............................................................................... 16
Maps............................................................................................. 17
Faculty By Research Area ............................................................... 17
Inscc Building Map ........................................................................ 19
Dept. of Physics & Astronomy
University of Utah

S ESSION 1
S ESSION 2
S ESSION 3
Schedule of Presentations
Time Room Title Speaker
8:50-9:00 AM Lobby Welcome
9:00 AM 110 INSCC
9:15 AM 110 INSCC
9:30 AM 110 INSCC
9:45 AM 110 INSCC
10:00 AM 110 INSCC
10:15 AM 110 INSCC
High Angular Resolution Imaging with
Intensity Interferometry Using Air Cherenkov
Telescope Arrays
Long Spin Coherence Lifetimes of Optically
Generated Excitations in Colloidal CdS
Nanorods
Room Temperature Charge Carrier Spin
Quantum Phase Coherence in Organic
Semiconductors
Verifying the Presence of the Hyperfine
Interaction In LED's
Using A Nanostructure to Redirect
Fluorescence Emission from Individual
Quantum Dots
Collisional 3He & 129Xe Frequency Shifts in
Rb–Noble-Gas Mixtures
9:30-9:45 AM Lobby Break
11:00 AM 110 INSCC Charmonium Spectroscopy in Lattice QCD
11:15 AM 110 INSCC Recent Progress in Levin-Wen Models
11:30 AM 110 INSCC
Particle Dynamics in the Galaxy's
Gravitational Potential
11:45 AM 110 INSCC Superconducting Isotope Effect in Lithium
12:00 PM 110 INSCC
12:15 PM 110 INSCC
12:30 PM 110 INSCC
High Pressure Methods for Observing the
Lithium Melting Line
Live Imaging of Escrt Recruitment in Virus
Budding
Vesicular Stomatitis Virus Glycoprotein
Microdomain Organization
1:00-2:00 PM Lobby Lunch
2:00 PM 110 INSCC Dark Matters
2:15 PM 110 INSCC
2:30 PM 110 INSCC
2:45 PM 110 INSCC
3:00 PM 110 INSCC
3:15 PM 110 INSCC
3:30 PM 110 INSCC
Using Chemical Signatures of Kinematically
Selected Stars to Trace Galactic Mergers
On the Na-O Anticorellation & Other
Abundances in NGC 1261
A Proposal for a Low Resolution Stellar
Abundance Derivation Technique
Raman Spectroscopy Studies of Meteoritic
Structures: Implications for Planet Formation
Summer 2011 VERITAS Observations of
Nearby Blazar "BL Lac"
Radar Chirps from Extragalactic Cosmic Ray
Air Showers
3:45 -4:30 PM Lobby Poster Session
Paul Nunez
Graduate Student
Kipp van Schooten
Graduate Student
Will Baker
Graduate Student
Thomas Van Hook
Ugraduate Student
Anil Ghimire
Graduate Student
Zayd Ma
Graduate Student
Song-haeng Lee
Graduate Student
Yuting Hu
Graduate Student
Benjamin Czaja
Ugraduate Student
Barun Gupta
Graduate Student
William Talmadge
Ugraduate Student
Pei-I Ku
Graduate Student
Xiaolin Tang
Graduate Student
Luca Visinelli
Graduate Student
Dylan Gregersen
Ugraduate Student
Dan Filler
Ugraduate Student
Tim Anderton
Ugraduate Student
Bhuwan Ghimire
Ugraduate Student
Spencer Hatch
Ugraduate Student
Jamie Rankin
Ugraduate Student
2

Abstracts
RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
High Angular Resolution Imaging With Intensity Interferometry Using
Air Cherenkov Telescope Arrays
Paul Nunez, Graduate Student, nunez.paul@gmail.com
Dr. Stephan LeBohec, www.physics.utah.edu/gammaray
9:00 AM
Most stars are still merely detected as point sources at optical frequencies, and not as
extended objects. This has motivated the development of several interferometric
techniques in order to observe their structure at high angular resolution. Intensity
interferometry measures the correlation of intensity fluctuations between neighboring
detectors, which in turn provides information about the Fourier transform of the stellar
object. Planned air Cherenkov telescope arrays will be ideal for the implementation of
optical intensity interferometry. These arrays will contain nearly 100 telescopes separated
by up to 1km, and will provide means to resolve stellar structures in the sub-milliarcsecond
scale. Current efforts towards sub-milliarcsecond imaging with intensity interferometry will
be discussed.
Long Spin Coherence Lifetimes Of Optically Generated Excitations In
Colloidal CdS Nanorods
Kipp van Schooten, Graduate Student, kippvs@physics.utah.edu
Dr. Christoph Boehme/Dr. John Lupton
www.physics.utah.edu/~boehmelab/research.html
9:15: AM
The nature, interactions and dynamics of optically excited spin states in quantum dot
systems has recently been intensely investigated due to the wealth of materials
information it gives, as well as the exciting potential for spintronic and quantum
information applications. In particular, spin coherence lifetimes (T2 times) long enough to
make quantum correction algorithms feasible and hyperfine coupling to nuclear spins that
allows for spin storage via dynamic nuclear polarization (DNP) processes have been highly
desired. Therefore, the characterization of new candidate spin centers is potentially of
technological significance and is certainly of value to materials research. Here, we describe
our recent observation of long T2 times (>1.5ms) for optically generated excitations in
colloidal CdS nanorods at 3.5K. These optically generated states possess very long radiative
lifetimes, which results in there being a large population of excited states that persists
beyond 100ms after excitation. This, in turn, leaves a spin population that exists on time
scales to which pulsed magnetic resonance schemes are very sensitive. An optically
detected magnetic resonance (ODMR) scheme is then used to manipulate the spin states
which are associated with these optical excitations. Coherent spin manipulation is
demonstrated and this ultimately allows us to measure the system’s true T2 time by
employing a Hahn echo microwave pulse sequence. In addition to gaining the spin
coherence time, we also report on the simultaneous observation of a more subtle
interaction between this excited state and its surrounding environment. The presence of
this interaction is witnessed as a finer structure splitting in the already Zeeman-split energy
levels and is manifested by a modulation of the spin echo amplitude. The exact mechanism
involved (hyperfine, nuclear quadrupole, etc.) is still under investigation
3

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Room Temperature Charge Carrier Spin Quantum Phase Coherence In
Organic Semiconductors
Will Baker, Graduate Student, bakerwillis@gmail.com
Dr. Christoph Boehme/Dr. John Lupton
www.physics.utah.edu/~boehmelab/research.html
9:30 AM
This work represents the first room temperature spin-phase storage and recovery
experiment done with an organic polymer device (OLED) measured with a novel electron
spin resonance technique, namely pulsed electrically detected magnetic resonance
(pEDMR) which is sensitive to the mutual spin orientation of spin pairs. This experiment
has allowed us to not only obtain the true spin-phase coherence times (different from
dephasing or spin-mixing times), but has also enabled us to gain insight into the
equilibrium transport mechanisms. Consequently, the results have given a confirmation of
the important role the hyperfine interaction plays in the spin relaxation times. Possibly the
most important result from the given work is the surprisingly weak temperature
dependence in intra-molecular hopping within the formed e-h pair which hints to a slow
tunneling transport mechanism instead of the widely accepted thermally driven phononassisted
hopping model.
Verifying The Presence Of The Hyperfine Interaction In Led's
Thomas Van Hook, Ugraduate Student, strwrs287@comcast.net
Dr. Brian Saam, www.physics.utah.edu/~hpgas
9:45 AM
10:00 AM
We have been investigating a particular effect present in the organic light-emitting diodes
we have constructed. As current passes through the OLED, the amount of resistance in the
OLED varies according to the strength of the magnetic field acting upon the device. The
most likely explanation for this effect is the manifestation of the hyperfine interaction. If
the HFI is the cause, we can also change the current by manipulating the 1H spins in the
organic substrate through the use of NMR techniques. Current data is preliminary but
progressing towards the end goal of determining whether or not the hyperfine interaction
creates this effect we see. If indeed the hyperfine interaction is present in this device, the
design could be further adapted to create spintronic devices.
Using A Nanostructure To Redirect Fluorescence Emission From
Individual Quantum Dots
Anil Ghimire, Graduate Student, anghimire@hotmail.com
Dr. Jordan Gerton, www.physics.utah.edu/~gertonlab
We studied the angular emission pattern from individual quantum dots in the presence of
sharp atomic force microscope tips. In particular, we used a unique data acquisition
system to measure changes in the polarization state of the emitted light as the distance
between a tip and quantum dot was varied with nanometer-scale precision. The
reorientation of the polarization reflects changes in the directionality of the emitted light.
Several possible mechanisms for the redirection of emission will be discussed.
4

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Collisional 3He And 129Xe Frequency Shifts In Rb–Noble-Gas Mixtures
Zayd Ma, Graduate Student, zaydma@physics.utah.edu
Dr. Brian Saam, www.physics.utah.edu/~hpgas
10:15 AM
This talk will explain the physics and results of our groups most recent PRL "Collisional 3He
and 129Xe Frequency Shifts in Rb–Noble-Gas Mixtures ". The Fermi-contact interaction that
characterizes collisional spin exchange of a noble gas with an alkali-metal vapor also gives
rise to NMR and EPR frequency shifts of the noble-gas nucleus and the alkali-metal atom,
respectively. We have measured the enhancement factor κ0 that characterizes these shifts
for Rb-129Xe to be 493±31, making use of the previously measured value of κ0 for Rb-3He.
This result allows accurate 129Xe polarimetry with no need to reference a thermalequilibrium
NMR signal.
Charmonium Spectroscopy In Lattice QCD
Song-haeng Lee, Graduate Student, song@physics.utah.edu
Dr. Carleton Detar, www.physics.utah.edu/~detar
11:00 AM
11:15 AM
Charmonium, discovered in 1974 at Brookhaven and SLAC, is a bound state of a charm
quark and anti-charm quark. It provides one of the most useful tests of the theory of strong
forces. In analogy to the bound state e+e- called positronium in which photons mediate
the electromagnetic force (Quantum Electrodynamics), in charmonium, gluons mediate
the strong force between the quark and anti quark (Quantum Chromodynamics). The key
difference between them is the properties of the positronium states can be theoretically
determined by traditional methods, whereas, charmonium states cannot. However recent
advances in high-precision numerical computer simulation make the problem solvable
(Lattice Quantum Chromodynamics). That is, now, we can evaluate the spectrum of
charmonium and match it with the experimental values. Moreover, it is possible to guide
the discovery of new states. In this presentation, I talk about the basics of LQCD briefly and
the current process of the charmonium project.
Recent Progress In Levin-Wen Models
Yuting Hu, Graduate Student, yuting.phys@gmail.com
Dr. Carleton Detar, www.physics.utah.edu/~detar
In recent years, two-dimensional topological phases have received growing attention in
condensed matter physics and topological quantum computation. Exactly soluble lattice
models that describe doubled topological phases were proposed by Kitaev, and Levin and
Wen respectively. Here I present a summary of the following progress in these models: the
ground state degeneracy, and the fractional statistics of flux-type quasiparticles.
5

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Particle Dynamics In The Galaxy's Gravitational Potential
Benjamin Czaja, Ugraduate Student, b.czaja@utah.edu
Dr. Ben Bromley, www.physics.utah.edu/~bromley
11:30 AM
The purpose of this project is to study the effects that our Galaxy’s gravitational potential
has on photons from the Cosmic Microwave Background (CMB). The CMB is a bath of
photons that are relics of the Universe at early times following the big bang. Photons in
the bath propagate freely in space, but can be deflected from their original paths by the
gravitational potential of our Galaxy, the Milky Way. To study this deflection of light I
numerically simulated the path of light rays as they travel through a three-component
model of the Galaxy, with a disk, a central bulge, and an extended halo. Specifically, I
traced light rays deflected by the Galaxy’s gravity according to General Relativity, as they
travel from an observer located at a position near the Sun. The results show that the
amount of deflection increases as the light rays travel closer to the center of the galaxy;
having a maximum deflection angle of 0.812037 arc seconds when traveling through a
region 161.99 arc minutes away from the galactic center. The significance of this work is
the prediction of a potentially measurable distortion the CMB by the galaxy. In principle
we may use these distortion to map out the gravitational potential of the galaxy.
Superconducting Isotope Effect In Lithium
Barun Gupta, Graduate Student, barungupta05@gmail.com
Dr. Shanti Deemyad, www.physics.utah.edu/~deemyad
11:45 AM
Lithium is the lightest elemental superconductor. While the superconducting transition
temperature Tc of lithium is very low at ambient pressure, Tc reaches 20K under pressure.
Due to its light mass, ionic quantum motion may have a substantial contribution to the
lattice dynamics of lithium, and the isotope effect in superconducting lithium may reveal
interesting physics. While the superconducting phase diagram of Li7 under pressure is
well studied, the superconductivity of Li6 has not been studied experimentally. In this talk,
I will present our experimental approach in studying the superconducting isotope effect in
pressurized lithium and discuss possible interesting outcomes of this study.
6

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
High Pressure Methods For Observing The Lithium Melting Line
William Talmadge, Ugraduate Student, willtalmadge@gmail.com
Dr. Shanti Deemyad, www.physics.utah.edu/~deemyad
12:00 PM
Theoretical work has suggested that lithium has the unusual property that its melting
point decreases rather dramatically as pressure is increased from 12 GPa to 40 GPa. In fact
the melting temperature is predicted to reach a minimum as low as 200 K. This has
suggested the possibility of the formation of a quantum fluid. Some experimental work
provides evidence of this cold melting in lithium. However, the entire phase diagram from
15 GPa to 100 GPa, and beyond is not well observed. We present experimental apparatus
and methods that allow direct observation of this melting line at high pressure. We
generate the extreme pressures needed by placing the sample within a diamond anvil cell.
When high temperatures are needed for melting we use an infrared laser to melt the
sample and measure these temperatures with a high sensitivity pyrometer. The melting
point is observed and confirmed with two methods. We can observe a laser speckle pattern
in situ to observe physical changes in the surface of the material caused by melting.
Additionally we can finely control how much a sample is heated and observe the
temperature plateau that results from the enthalpy of fusion of lithium. If the melting line
decreases below room temperature we will use a conventional cryostat to follow the meltline.
Live Imaging Of Escrt Recruitment In Virus Budding
Pei-I Ku, Graduate Student, peii39@gmail.com
Dr. Saveez Saffarian, www.physics.utah.edu/~saffarian
12:15 PM
While recent years have seen rather dramatic advances in our understanding of how
enveloped viruses achieve separation from their cellular hosts, several pressing questions
remain. One central question is the precise role of ESCRT (Endosomal Sorting Complexes
Required for Transport) proteins, which normally play an essential role in fundamental
intracellular pathways, in virus release. Additional problems are assigning specific roles in
viral processing to Alix (a cellular Class E protein that interacts directly with the ESCRT
machinery to facilitate viral assembly and release) and, in the case of HIV, to the L-domains
of Gag (responsible for recruiting cellular factors that facilitate budding for HIV-1). Several
plausible hypotheses have been proposed based on studies of multivesicular bodies
(MVBs) and in vitro experiments. In order to observe the viral budding process in vivo in
cell membranes and to elucidate the interactions and functions of Gag-Alix-ESCRT, we
have employed total internal reflection florescence microscopy (TIRF-M) to analyze
assembly and budding in live cells and to quantitatively examine the interactions of Gag-
Alix-ESCRT, from initiation of assembly to budding and release. I am currently focusing on
how Alix is recruited to the cell membrane and on its interactions with Gag.
7

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Vesicular Stomatitis Virus Glycoprotein Microdomain Organization
Xiaolin Tang, Graduate Student, ttxiaolin@gmail.com
Dr. Saveez Saffarian, www.physics.utah.edu/~saffarian
12:30 PM
2:00 PM
Virus budding continues to be a critical area of study in virology. Important questions
include where, when, and how this process occurs and what ensures that it proceeds
smoothly. We are particularly interested in the initiation of virus budding, specifically
whether the budding site is specifically directed or whether it is simply a random choice,
and what initiates this process. In the case of vesicular stomatitis virus (VSV) the actions of
its glycoprotein (VSVG), its only transmembrane protein, have been thought to be essential
to the above questions. Most membrane proteins, including viral envelope glycoproteins,
are considered to be organized into locally concentrated areas referred to as membrane
microdomains. These microdomains are thought to be the sites of virus budding and even
the entry sites for virus. In previous studies, Lyles and Brown used a novel method in
conjunction with thin-section immuno-gold EM to determine that VSVG is organized into
microdomains on the plasma membrane and that the microdomains eventually form virus
budding sites. However, these microdomain data have not yet been confirmed in
experiments with live cells. Fluorescence correlation spectroscopy (FCS) is a powerful tool
that can detect fluctuations such as diffusion without disturbing a system, which makes it
especially useful in live cell experiments. We are using this tool to investigate how VSVG
protein is organized on the plasma membrane during transfection and infection, and we
aim to calculate the microdomain size if it indeed exists. In addition, we have the capability
to observe the organization of two different VSV proteins simultaneously—e.g., G and M, G
and N, and even G and the VSV ribonucleic protein complex (RNP) —by labeling with two
differently colored fluorescent proteins and thus study interactions between these
proteins. This will allow us to address multiple questions, such as whether or not G protein
is involved in assembly of the internal virion components in budding, and whether the
interaction between them can initialize the assembly process. The answers to these
questions will help us to construct a better model of virus budding.
Dark Matters
Luca Visinelli, Graduate Student, luca.visinelli@gmail.com
Dr. Paolo Gondolo, www.physics.utah.edu/index.php/people/faculty/1096-gondolo
We will explore the reasons why Cold Dark Matter is needed to explain the evolution of the
universe. We will also briefly discuss the role of dark energy in the modern universe.
8

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Using Chemical Signatures Of Kinematically Selected Stars To Trace
Galactic Mergers
Dylan Gregersen, Ugraduate Student, dylan.gregersen@utah.edu
Dr. Inese Ivans, www.cosmic-origins.org
2:15 PM
Orbital characteristics and chemical signatures of stars are used as indicators of their
origins. Recent work by Allen et al. (2007) utilized catalog information of Milky Way halo
stars, classifying these stars into moving clusters based on similarities in orbital energy,
angular momentum, and metal content. My study has recently focused on deriving
chemical signatures of one candidate moving cluster which contains the wide binary star
pair HD 134439/134440. By employing high-resolution spectroscopy, chemical
abundances of all six stars in this select moving cluster are derived. Particular attention has
been given to α-elements (Mg, Ca, Si, and Ti), which trace star formation history. Low
enhancements of α-elements are often used to determine extragalactic origins. Initial
results from stars of this moving cluster reveals α enhancements of [α/Fe] ~ 0.1 – 0.3 dex,
which is lower than the enhancements common to halo stars of galactic origins ([ α/Fe] ~
0.5). This discovery supports Allen et al.'s claim that these stars are associated with a
discrete accretion event, such as the dissolution of a globular cluster or the merger of a
dwarf spheroidal galaxy into the Milky Way.
On The Na-O Anticorellation And Other Abundances In NGC 1261
Dan Filler, Ugraduate Student, danfiller1@gmail.com
Dr. Inese Ivans, www.cosmic-origins.org
2:30 PM
The evolution of globular clusters is not fully understood. However, by using chemical
abundances of stars we see today, astronomers are able to decipher what conditions may
have existed in the early Galaxy, and model the evolution of globular clusters. We present
the first spectroscopic analysis of the galactic cluster NGC 1261. Multi-line equivalent
width analysis, spectrum synthesis and model stellar atmospheres were employed to
derive elemental abundances for three stars in NGC 1261. The overall metallicity, [Fe/H] = -
1.10 +/- 0.02, is within expectations based upon photometric estimates. However, the Na-
O anti-correlation, spanning over 1.2 dex in sodium, is larger than any other cluster. This
anti-correlation is possibly from an earlier generation of stars in the cluster that may have
polluted the atmospheres of the current generation, or maybe polluted material from
which they were born. In addition to the neutron capture element EU, (which is created
from core collapse supernovae), abundances of the alpha elements (Mg, Ca, Si, and TI),
created by both core collapses and thermonuclear SNE, iron peak elements (V, Cr, MN, Co
and Ni) and the light elements (C, N and O), which also trace stellar nuclear synthesis, are
reported.
9

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
A Proposal For A Low Resolution Stellar Abundance Derivation
Technique
Tim Anderton, Ugraduate Student, quidditymaster@gmail.com
Dr. Inese Ivans, www.cosmic-origins.org
2:45 PM
Elemental abundances can be a powerful tool in tracing stellar evolution and
differentiating stellar populations with different origins. The method of individual line
analysis in high resolution spectroscopy allows excellent abundances of many elements to
be derived for stars with high a resolution and high signal to noise spectrum available. But
this technique becomes difficult or impossible as the data become progressively more
noisy or lower in resolution. The ready availability of large numbers of low resolution
spectra from surveys such as SDSS has spurred a number of methods for the determination
of iron abundances from such data. However, there is a dearth of techniques to use such
data to find the abundances of other specific elements, e.g. manganese, chromium,
titanium. I propose a new abundance derivation technique for use on low resolution data
which decomposes an observed spectrum into a continuum part and a set of deformations
which are associated with the absorption spectrum of elements at different abundance
levels. This decomposition can then be used to estimate stellar abundances. Preliminary
results will be shared.
Raman Spectroscopy Studies Of Meteoritic Structures: Implications For
Planet Formation
Bhuwan Ghimire, Ugraduate Student, BGhimire.12@westminster-mo.edu
Dr. Gerton, Dr. Ivans, Dr. Bromley, www.physics.utah.edu/~gertonlab
3:00 PM
A hierarchical model for the early stages of planet formation involves the coagulation of
micron-scale dust particles orbiting the sun into larger, centimeter- or meter-scale objects.
Computational simulations can produce planetary distributions that agree with
astronomical data when they start with planetesimals of 1 km or more in size. However, it is
unclear to date how these planetesimals arose from the dust. One possibility is that the
dust’s small-scale structure enhanced adhesion and coagulation. At very least, this
structure, as preserved in stony meteorites, may provide clues to the physical processes
during this critical juncture in planet formation. It is unclear of the adhesion property of the
dust aggregates ultimately leading to the formation of structures like planetesimals. Other
compounds including minerals might also have accumulated on the dust particles.
Confocal Raman microscopy was used to investigate the microstructures on meteorites.
They are composed of chondrules which were rich in our samples and inclusions which are
both embedded in the matrix material. Raman scattering produces an optical spectrum,
which when compared to reference spectra can yield information on the specific chemical
compounds present in and around the matrix of meteorites. To date, it has been possible
to distinguish the chondrules composed mainly of minerals like Olivine and Pyroxene, from
the matrix of pre-solar grains. Raman mapping of meteorite samples is pursued, with a
focus on the interfaces between chondrules and the matrix.
10

RESEARCH SYMPOSIUM ABSTRACTS
(arranged by session)
Department of Physics & Astronomy
Summer 2011 VERITAS Observations Of Nearby Blazar "BL Lac"
Spencer Hatch, Ugraduate Student, spencerhatch@weber.edu
Dr. Dave Kieda, www.physics.utah.edu/gammaray
3:15 PM
BL Lacertae (BL Lac) is a nearby (z ~ .0688) active galaxy with strong optical polarization
and variability, as well as a non-thermal emission spectrum. It is also the prototype of a
whole class of blazars known as ?BL Lac objects? which share similar polarization and
variability properties. Some objects belonging to this class have been identified as veryhigh
energy (VHE) emitters (E > 0.1TeV), while BL Lac has remained an unconfirmed source
of VHE gamma-ray emission until recently. In late May 2011, the Fermi Large Area
Telescope (LAT) reported observing BL Lac in a high gamma-ray state, which led to a brief
multi-wavelength campaign involving several institutions, including the Very Energetic
Radiation Imaging Telescope Array System (VERITAS) in southern Arizona. VERITAS
observed BL Lac for a total of nine hours over the course of several weeks, extending from
late May to early July. Standard analysis has yielded little evidence for gamma-ray emission
from BL Lac, with the very notable exception of a gamma-ray outburst on the evening of
June 28th. In this talk, I'll discuss the recent observations of BL Lac by VERITAS, as well as
potential constraints they may place on the origin of gamma-ray emission in BL Lac.
Radar Chirps From Extragalactic Cosmic Ray Air Showers
Jamie Rankin, Ugraduate Student, jamie.rankin@utah.edu
Telescope Array. www.telescopearray.org
3:30 PM
Ultra-High Energy Cosmic Rays (UHECRs) are cosmic rays with energies of 1018 eV and
higher. Comprised of the highest energy particles in the universe – many orders or
magnitude higher than man-made accelerator particles – one cannot help but wonder,
what astronomical objects can accelerate particles to this energy? No one knows. As a
result, by looking for anisotropy, collecting events, and studying UHECRs, large cosmic ray
experiments are trying to solve for clues as to what the sources might be. However, due to
the high cost in materials and physical space currently required to detect UHECRs, it is
unlikely that larger experiments can be built. Thus, we are currently exploring an
alternative method of detecting UHECR air showers by bouncing radio signals off of them.
In doing this, a transmitted signal hits an incoming air shower and the signal is reflected to
a receiver which, in turn, sees a time-dependent phase change equivalent to a frequency
shift. The resulting radio reflection with the frequency changing over time in this way is
called a chirp. This summer, I have been developing a program to simulate chirps at
varying geometries in order to investigate regularities in the signals with the goal of
eventually reconstructing air showers from these radio reflections.
11

POSTER SESSION ABSTRACTS
Department of Physics & Astronomy
Spin-Dependent Processes In Amorphous Silicon-Rich Silicon-Nitride
Sang-Yun Lee, Graduate Student, beryl236@gmail.com
Dr. Christoph Boehme, www.physics.utah.edu/~boehmelab/research.html
POSTER
Non-stoichiometric silicon-rich silicon-nitride(SiNx) has recently attracted attention as
material for tunable LEDs as well as for photoelectrochemical (PEC) hydrogen production
due to its electronic properties and its excellent resistance to corrosion. For any of these
applications, the understanding of charge transport and recombination are important as
both play an important role for optoelectronic properties of SiNx. Transport and
recombination in disordered silicon materials are strongly influenced by a variety of
localized, paramagnetic defect states and electron spin resonance (ESR) spectroscopy can
therefore be used to investigate how these states, influence charge transport and
recombination. We present here pulsed electrically detected magnetic resonance
experiments which are measurements of pulsed ESR induced changes of spin-dependent
photocurrents in SiNx p-i-n stacks at T=15 K. The measurements exhibit spin-Rabi
oscillations which allow a mapping of the observed spin-dependent signals as functions of
the Landé g-factors and different spin-coupling regimes of the involved spins. By these
means we observe the influence of dangling bond- and band tail-states as well as
combinations thereof. These observed spin-dependent currents involve paramagnetic
centers which are mutually uncoupled, dipolar-coupled or exchange-coupled, similar to
amorphous silicon (a-Si). However, unlike for a-Si:H, the transitions between strongly spincoupled
pairs in SiNx significantly influence the conductivity, and are therefore due to nongeminate
recombination processes. This demonstrates that adding a small amount of
nitrogen atoms enhances the conversion of geminate to non–geminate charge carrier
pairs in a-SiNx, indicating that this material when used for PEC electrodes could actually
lead to larger internal quantum efficiencies than pure a-Si:H.
HAWC Observatory
Ahron Barber, Graduate Student, ahron.barber@gmail.com
Dr. Dave Kieda, www.physics.utah.edu/gammaray
POSTER
HAWC (High Altitude Water Cherenkov Observatory) is a new all-sky TEV gamma ray
observatory being built on Sierra Negra, Mexico at an altitude of 4100 m. The all sky
coverage and high duty cycle will give HAWC approximately an order of magnitude
greater sensitivity than its predecessor, Milagro. The primary focus of HAWC is to study
Gamma Ray Bursts, galactic and extragalactic gamma ray sources, along with the large
scale cosmic ray anisotropy first observed by Milagro and ARGO. HAWC will also be used
for ground level solar physics.
12

POSTER SESSION ABSTRACTS
Department of Physics & Astronomy
Benchmarking SDSS-Segue Estimated Stellar Parameters Using High
Resolution Spectra Of SDSS Stars
Iranga Samarasingha, Ugraduate Student, u0664549@utah.edu
Dr. Inese Ivans, www.cosmic-origins.org
POSTER
We have analyzed the high-resolution spectra of 250 stars to estimate the stellar
parameters of the previously obtained low resolution data taken for the Sloan Extension
for Galactic Understanding and Exploration (SEGUE). SEGUE has gathered low-resolution
spectra covering the entire optical range of 240,000 stars in the Milky Way. SEGUE was
designed as one of the main projects of the Sloan Digital Sky Survey (SDSS) to explore the
chemical enrichment history of our galaxy. SDSS, the largest astronomical survey in the
history of humanity explores the universe by gathering images and spectra of millions of
objects in the sky. Studying the high resolution spectroscopic data gathered using the
following observatories and instruments (Keck: HIRES & ESI, Subaru: HDS, HET:HRS, and
VLT:UVES), we compute the stellar surface gravity measurements (the gravitational
acceleration at the surface of a star) to compare with the results of SEGUE Stellar Parameter
Pipeline. I have also derived the radial velocities and confirmed important stellar
atmospheric parameters such as effective temperature and metallicity. The comparison of
the resulting surface gravity measurements between the high resolution an low resolution
data will provide an insight into the accuracy of the methods used to derive the stellar
atmospheric parameters from the SEGUE spectroscopic observations. These results can be
applied to the significantly more distant stars, too dim to be observed via high-resolution
spectroscopy.
Crystal Orientation Induced Spin Rabi Beat Oscillations Of Point
Defects At The c-Si(111)/SiO2 Interface
Seoyoung Paik, Graduate Student, seoyoung.paik@gmail.com
Dr. Christoph Boehme, www.physics.utah.edu/~boehmelab/research.html
POSTER
Spin-dependent electronic transitions such as certain charge carrier recombination and
transport processes in semiconductors are usually governed by the Pauli blockade within
pairs of two paramagnetic centers. One implication of this is that the manipulation of spin
states, e.g. by magnetic resonant excitation, can produce changes to electric currents of
the given semiconductor material. If both spins are changed at the same time, quantum
beat effects such as beat oscillation between resonantly induced spin Rabi nutation
becomes detectable through current measurements [1]. Here, we report on electrically
detected spin Rabi beat oscillation caused by pairs of 31P donor states and Pb interface
defects at the phosphorous doped Si(111)/SiO2 interface. Due to the g-factor anisotropy
of the Pb center we can tune the intra pair Larmor frequency difference (so called Larmor
separation) through orientation of the sample with regard to the external magnetic field.
As the Larmor separation governs the spin Rabi beat oscillation, we show experimentally
how the crystal orientation can influence the beat effect.
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POSTER SESSION ABSTRACTS
Department of Physics & Astronomy
Constructing A Super-Resolution Fluorescent Imaging System Using A
Confocal Microscope Built By Undergraduates
Carl Ebeling, Graduate Student, carlgebeling@gmail.com
Dr. Jordan Gerton, www.physics.utah.edu/~gertonlab
POSTER
The incorporation of fluorescent proteins attached to specific target proteins within cells
using transgenic techniques has made light microscopy a powerful tool in the research of
biological specimens, allowing for the study of protein location in cells. Due to the
diffraction limit, however, fluorescent proteins can only be resolved to a separation of
approximately λ/2, or ~200-250 nm, in conventional imaging systems. Super-resolution
optical imaging has provided a method to overcome this barrier, beginning with pointspread
function engineering (STED), and now with localization techniques (PALM, FPALM,
BP-FPALM, and DH-PSF). While fluorescent proteins are versatile and powerful cellular
markers, they have low photon-yields, which provides a limitation to localization ability.
Microscopy methods that decrease the photo-bleaching rate of fluorescent proteins,
thereby increasing the photon-yield, are key to increasing the localization accuracy of such
techniques. We investigate here the use of a scanning confocal PALM microscope built by
undergraduate students in an attempt to increase the photon-yield from individual
fluorophores by allowing for fluorophore relaxation between rounds of excitation.
Undergraduate students from physics, biochemistry, mathematics, electrical engineering
and computer science worked together over the course of a semester to construct a
confocal instrument with an analysis software package to perform super-resolution
imaging.
Studies In Asymmetric Properties Of Vesicular Stomatitis Virus (VSV)
Jeff Hodges, Graduate Student, physicswannabe@gmail.com
Dr. Saveez Saffarian, www.physics.utah.edu/~saffarian
POSTER
POSTER
Vesicular stomatitis virus (VSV) is an envelope virus similar to rabies with some very
interesting uses in modern science such as drug delivery in oncology. Despite its uses,
many of the physical properties of the virus have only been studied in vitro on nonfunctioning
viruses; these processes are often very destructive and lack an in vivo
understanding. My research has focused on the physical properties of live VSV samples,
focusing on the asymmetric bullet shape of the virus. Using optical microscopy, and atomic
force microscopy I wish to see if the topological shape correlates with asymmetries within
the internal structure of the functional virus.
Higher Order Tensor Decomosition
Fangxiang Jiao, Graduate Student, fjiao@sci.utah.edu
Dr. Chris Johnson, www.sci.utah.edu
No abstract submitted.
14

POSTER SESSION ABSTRACTS
Department of Physics & Astronomy
Superconductivity In Low Z Materials
Scott Temple, Ugraduate Student, scottrtemple@gmail.com
Dr. Shanti Deemyad, www.physics.utah.edu/~deemyad
POSTER
Our upcoming research project focuses on superconductivity of lithium under high
pressure, and the impact of isotope effects on the superconducting transition temperature.
Lithium is the lightest superconducting element, and has a significantly higher Tc under
pressure than it does at ambient. We will generate megabar range pressures using a
diamond anvil cell (DAC), and observe the superconducting transition temperature as
pressure changes. We will perform this experiment with both lithium 6 and lithium 7.
Lithium 6 under pressure has not been well studied, and there may be significant variation
because of isotope effects. I will focus on the experimental methods we will use in this
study.
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Participants
Name Email Advisor
Tim Anderton quidditymaster@gmail.com Dr. Inese Ivans
Will Baker bakerwillis@gmail.com Dr. Boehme & Dr. Lupton
Ahron Barber ahron.barber@gmail.com Dr. Dave Kieda
Benjamin Czaja b.czaja@utah.edu Dr. Ben Bromley
Carl Ebeling carlgebeling@gmail.com Dr. Jordan Gerton
Dan Filler danfiller1@gmail.com Dr. Inese Ivans
Anil Ghimire anghimire@hotmail.com Dr. Jordan Gerton
Bhuwan Ghimire
BGhimire.12@westminster-mo.edu
Dr. Bromley, Dr. Gerton, &
Dr. Ivans
Dylan Gregersen dylan.gregersen@utah.edu Dr. Inese Ivans
Barun Gupta barungupta05@gmail.com Dr. Shanti Deemyad
Spencer Hatch spencerhatch@weber.edu Dr. Dave Kieda
Jeff Hodges physicswannabe@gmail.com Dr. Saveez Saffarian
Yuting Hu yuting.phys@gmail.com Dr. Carleton Detar
Fangxiang Jiao fjiao@sci.utah.edu Dr. Chris Johnson
Pei-I Ku peii39@gmail.com Dr. Saveez Saffarian
Sang-Yun Lee beryl236@gmail.com Dr. Christoph Boehme
Song-haeng Lee song@physics.utah.edu Dr. Carleton Detar
Zayd Ma zaydma@physics.utah.edu Dr. Brian Saam
Paul Nunez nunez.paul@gmail.com Dr. Stephan LeBohec
Seoyoung Paik seoyoung.paik@gmail.com Dr. Christoph Boehme
Jamie Rankin jamie.rankin@utah.edu Telescope Array
Iranga Samarasingha u0664549@utah.edu Dr. Inese Ivans
Eric Sorte egsorte@gmail.com Dr. Brian Saam
William Talmadge willtalmadge@gmail.com Dr. Shanti Deemyad
Xiaolin Tang ttxiaolin@gmail.com Dr. Saveez Saffarian
Scott Temple scottrtemple@gmail.com Dr. Shanti Deemyad
Thomas Van Hook strwrs287@comcast.net Dr. Brian Saam
Kipp van Schooten kippvs@physics.utah.edu Dr. Boehme & Dr. Lupton
Luca Visinelli luca.visinelli@gmail.com Dr. Paolo Gondolo
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Maps
Faculty By Research Area
Experimental Research Faculty
Astronomy & Astrophysics
Adam Bolton 801-585-5383 bolton@physics.utah.edu
Kyle Dawson 801-581-4785 kdawson@physics.utah.edu
Inese Ivans 801-585-5483 iii@physics.utah.edu
David Kieda 801-581-5220 kieda@physics.utah.edu
Stephan LeBohec 801-587-9923 lebohec@physics.utah.edu
Anil Seth
aseth@physics.utah.edu
Atomic Physics
Brian Saam 801-585-5832 saam@physics.utah.edu
Biophysics
Jordan Gerton 801-585-0068 jgerton@physics.utah.edu
Saveez Saffarian 801-581-5716 saffarian@physics.utah.edu
Michael Vershinin 801-581-5803 vershinin@physics.utah.edu
Cosmic Ray
Tareq Abu-Zayyad 715-425-3911 tareq@cosmic.utah.edu
John Belz 801-585-9620 belz@cosmic.utah.edu
Douglas Bergman 801-585-5973 bergman@physics.utah.edu
Robert Cady 801-585-0060 rcady@physics.utah.edu
George Cassiday 801-581-6635 cassiday@physics.utah.edu
Charlie Jui 801-581-7186 jui@physics.utah.edu
John Matthews 801-581-5505 jnm@cosmic.utah.edu
Pierre Sokolsky 801-581-5398 ps@physics.utah.edu
Gordon Thomson 801-585-1849 thomson@physics.utah.edu
Kai Martens 810-578-85-9677 kai.martens@ipmu.jp
Jonathan Ormes 303-871-3552 jormes@du.edu
Wayne Springer 801-585-1390 springer@physics.utah.edu
Thomas Gaisser 302-831-8113 gaisser@bartol.udel.edu
Experimental Condensed Matter
David Ailion 801-581-6973 dailion@physics.utah.edu
Christoph Boehme 801-581-6806 boehme@physics.utah.edu
Andrey Chubukov 608-262-1139 chubukov@physics.wisc.edu
Shanti Deemyad 801-585-5955 deemyad@physics.utah.edu
John Lupton 801-581-6408 lupton@physics.utah.edu
Fritz Luty 801-581-7446 luty@physics.utah.edu
Arun Madan 303-273-3543 amadan@mines.edu
Tho Nguyen 801-581-7078 thonguyen08@gmail.com
Andrey Rogachev 801-585-0792 rogachev@physics.utah.edu
Orest Symko 801-581-6132 orest@physics.utah.edu
Valy Vardeny 801-581-8372 val@physics.utah.edu
Clayton Williams 801-585-3226 clayton@physics.utah.edu
George Williams 801-581-6570 gaw@physics.utah.edu
Robert Blinc 386-1476-6581 fmf@fmf.uni-lj.si
Eitan Ehrenfreund 972-04-829-3610 eitane@physics.technion.ac.il
Dane McCamey 9351-2357 d.mccamey@physics.usyd.edu.au
High Energy Astrophysics
Petra Huentemeyer 906-487-1229 petra@mtu.edu
Health & Medical Physics
Werner Gellermann 801-581-5222 werner@physics.utah.edu
Gernot Laicher 801-585-5553 gernot@physics.utah.edu
Richard Ingebretsen 801-581-7166 richi47@comcast.net
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Faculty By Research Area
Experimental Research Faculty
Dennis Parker 801-581-8643 parker@ucair.med.utah.edu
Eun-Kee Jeong 801-581-8643 ekj@ucair.med.utah.edu
Steven Blair 801-581-6941 blair@ece.utah.edu
Ajay Nahata 801-581-6941 nahata@ece.utah.edu
Julio Facelli 801-585-3791 julio.facelli@utah.edu
Christopher Johnson 801-581-8528 crj@sci.utah.edu
Gerald Stringfellow 801-581-8387 stringfellow@coe.utah.edu
Theoretical Research Faculty
Astrophysics, Relativity & Cosmology
Ben Bromley 801-581-8227 bromley@physics.utah.edu
Paolo Gondolo 801-581-7788 paolo@physics.utah.edu
Zheng Zheng
zhengzheng@physics.utah.edu
Chemical Physics
Frank Harris 801-581-8445 harris@physics.utah.edu
Feng Liu 801-587-7719 fliu@eng.utah.edu
Michael Bartl 801-585-1120 bartl@chem.utah.edu
Education
John DeFord 801-581-8396 golfcalc@aol.com
Lynn Higgs 801-581-7140 higgs@physics.utah.edu
Richard Ingebretsen 801-581-7166 richi47@comcast.net
Tony Pantziris 801-585-7653 app@physics.utah.edu
Sid Rudolph 801-581-4803 sid@physics.utah.edu
Chris Stone 801-402-3910 cstone@physics.utah.edu
Elementary Particle Physics
James Ball 801-581-8397 ball@physics.utah.edu
Carleton DeTar 801-581-7537 detar@physics.utah.edu
Yong-Shi Wu 801-581-6603 wu@physics.utah.edu
Pearl Sandick
sandick@physics.utah.edu
Relativity
Karel Kuchar 801-581-5083 kuchar@physics.utah.edu
Richard Price
rhp@physics.utah.edu
Theoretical Condensed Matter
Alexei Efros 801-585-5018 efros@physics.utah.edu
Dan Mattis 801-581-5803 mattis@physics.utah.edu
Eugene Mishchenko 801-581-7115 mishch@physics.utah.edu
Vagharsh Mkhitaryan 801-581-6203 vgho@physics.utah.edu
Mikhail Raikh 801-585-5017 raikh@physics.utah.edu
Oleg Starykh 801-581-6424 starykh@physics.utah.edu
John Worlock 801-581-4483 worlock@physics.utah.edu
Prabasaj Paul 740-587-6223 paul@denison.edu
Tigran Shahbazyan 601-979-3619 tigran.shahbazyan@jsums.edu
Boris Shapiro 972-04-829-3780 boris@physics.technion.ac.il
Theoretical High Energy
James Bjorken 650-723-4344 bjorken@slac.stanford.edu
Gabriel Karl 519-824-4120 kgabriel@uoguelph.ca
18

INSCC Building Map
19

University of Utah:
Physics & Astronomy
201 James Fletcher Bldg.
115 South 1400 East
Salt Lake City, UT 84112-0830
Phone (801) 581-6901
Fax (801) 581-4801
www.physics.utah.edu
www.physics.utah.edu
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