Student Research Talks

Detection of magnetic biomarkers using a single giant magneto-impedance microwire.

Claire Albrecht

A combination of magnetic sensors and superparamagnetic nanoparticles provides a novel biosensing platform for detection of cancer cells and biomolecules. In this study, we demonstrate the excellent capacity of detecting 10 nm iron oxide nanoparticles at various concentrations up to 40 mg using a single microwire (Co69.25Fe4.25Si13B12.5Nb1; d=60 µm) based sensor. The change in impedance of the microwire was measured using an impedance analyzer (1 MHz – 1 GHz) when exposed to the stray magnetic field from the nanoparticles. The detection sensitivity of the sensor is greatly enhanced by supplying a small DC field just below the anisotropy field of the microwire (HK = 3.5 Oe). The external field dependence of the detection demonstrates the microwire as a tunable RF magnetic sensor for small magnetic fields. In addition, we utilize the linear low-field impedance response as a new method for determination of the stray field strength of the detected nanoparticles.

Outflows and star-formation feedback from young stellar objects in NGC1333

Natalie Allen

NGC1333 is an active star-forming region in Perseus containing many young stellar objects (Class 1 and Class 0 protostars), as well as 17 outflows. Along these outflows are shock regions, from which the spectral line emissions of dominant coolants are used to make accurate rate measurements of the mass, momentum, and thermal energy deposited into the surrounding cloud. Simulated shocks from the Mappings V program are matched to emission spectra from the Spitzer Space Telescope`s Infrared Spectrograph to determine the pre-shock factors that establish these rates. Using these matches, we can come to an understanding of star-formation feedback on the cloud, as well as the eventual fate of the NGC 1333 cloud.

Environment-Assisted Quantum Transport in Photosynthetic Compounds

Sam Alterman

Generally in physics, noise is a destructive process. However, recent research has indicated that in the FMO complex of photosynthetic bacteria, environmental noise can actually increase the efficiency of exciton transport. Much of the previous work on this subject has only considered the regime where all transport sites are at the same energy level; however, our work indicates there is an additional regime where differences in energy can be beneficial to transport efficiency.

Floquet topological phases in non-Hermitian Hamiltonians

Elizabeth Blose

In this ongoing project, we calculate the Floquet quasi-energy spectra of several parity-time (PT) symmetric one-dimensional lattices with non-Hermitian, time dependent Hamiltonians. The PT symmetry of the system guarantees that the energy spectrum will be entirely real, or else that energies will come in complex-conjugate pairs. We also search for mid-gap energy modes, a common signature of topological phases.

Lorentz Symmetry Breaking in Horava-Livshitz Gravity

Hannah Bossi

Horava-Livshitz gravity is a theory of quantum gravity distinguished by anisotropic scaling in the high-energy, or ultra-violet (UV), limit, which violates Lorentz invariance. In the low energy, or infrared (IR), limit Horava-Livshitz gravity should agree with general relativity with small signals associated with Lorentz violation. In this talk, I will present an overview of my exploratory work with Horava gravity and discuss my current investigations of the effects of this Lorentz violation.

Studying Cosmic-Ray Neutrons

Emma Clarke

Galactic cosmic-ray (GCR) interactions in Earth's atmosphere produce “albedo" neutrons that move upwards, decay, and populate the inner radiation belt with energetic protons. Measurements of these neutrons are typically made during one-day balloon flights. However, the intensity of GCRs and solar energetic particles (SEPs) are known to vary greatly over the solar cycle. To understand the inner radiation belt particle budget one must know the inputs as well as the losses. We report measurements of 20 to 100 MeV atmospheric albedo neutrons made in low earth orbit. The data were obtained with the COMPTEL instrument on NASA's Compton Gamma-Ray Observatory (CGRO). The data were collected over 26 days between April 1992 and February 1998 for a total acquisition time of approximately 24 hours. For this study we selected only the nadir-looking measurements. The observations cover a range of 4.55 to 12.91 GV in geomagnetic cutoff rigidity, an equivalent range of ± 39 degrees in geomagnetic latitude. The instrument efficiency values used to evaluate the neutron intensities were obtained from Monte Carlo simulations. With some exceptions, the resulting energy spectrum and angle distribution agree with the results of Ait-Ouamer et al. (1988) obtained from a balloon payload.

High Energy Gamma-Ray Astrophysics with HAWC

Lindsey Diehl

Despite the discovery of cosmic rays over 100 years ago, we still debate the origin and acceleration mechanisms of energetic nuclei, electrons, and positrons striking the atmosphere of the Earth. Extreme high-energy gamma rays (from 10s to 100s of TeV) have the potential to unveil galactic cosmic-ray sources by probing nuclei acceleration in these sources. The High Altitude Water Cherenkov (HAWC) Observatory, operating at a high-altitude site in Mexico, is providing a new window on the extreme high-energy gamma-ray sky. I will describe the HAWc instruments and summarize our most interesting results on cosmic-ray physics.

Seasonal Onset Trends

Brittney Herold

In recent years it has become obvious that the onset of seasons like winter and summer do not begin around the periods we used to expect. In this research, data was analyzed to see if these suspicions held true. To do this, six stations were selected, two coastal, two inland, and two urban areas ranging from Upstate New York to Eastern Pennsylvania. Using Python Programming Language, onsets of winter and summer were calculated and then applied to every year for 51 years at all stations. The results show that winter's onset is arriving later than it did before the 1980's and summer is arriving earlier.

Noise Simulation for Xenon

Olenka Jain

The XENON experiment is a dark matter detection experiment housed underground at the Laboratori Nazionali de Gran Sasso in Italy (LNGS). The experiment uses a dual-phase Time Projection Chamber (TPC) to detect direct collisions between Xenon nuclei and weakly interacting massive particles (WIMPS). The most recent detection chamber, XENON1T, is the worlds most sensitive direct dark matter detector. To understand and analyze the data, a Monte Carlo simulation is used. My project this summer was to analyze the noise inherent in the detector and create a noise simulation for the Monte Carlo which makes the noise random and coherent.

Evolution of the Galaxy Merger Rate out to z=3

Carly KleinStern

Galaxy mergers are integral to black hole and stellar mass accretion, but there is controversy regarding how the merger rate evolves over cosmic time. We investigate the evolution of the galaxy merger rate out to z=3. We find strong evolution up to z=1, and then a sudden drop afterwards that is unexpected, and we think, artificial. Further exploration of selection effects is necessary. We first find a pair fraction. In order to identify merger candidates, we use optical and infrared data from the multiwavelength COSMOS survey. We consider only major mergers, and check whether the redshift probability distributions place two given galaxies at similar redshifts (thus implying they are physically close). Next, we find the distance to the closest neighbor of each galaxy that fits the aforementioned criteria. We will statistically correct for chance line-of-sight projections (galaxies that appear to be close, but are not actually). Our next steps include choosing an observability timescale to convert the fraction into a rate, comparing our observational results to the results from the Illustris cosmological simulation, and seeing how our results fit in with the literature.

Fabricating Superconductor-Semiconductor Nanowire Devices

Eunice Lee

Majorana particles may be the key to topological quantum computing, but their existence has yet to be decisively confirmed. Evidence for Majorana bound states has been found in hybrid superconductor-semiconductor nanowire devices. My presentation reports on the fabrication and measurement of hybrid devices that couple indium antimonide (InSb) nanowires to a superconductor that is either niobium (Nb) or aluminum (Al). Clean epitaxial contact of Nb to InSb was achieved. Further work is needed to optimize the procedures to fabricate functional Nb/InSb devices and complete the Al/InSb devices

Quantizing Plane Gravitational Waves in Loop Quantum Gravity

Elise LePage

In loop quantum gravity, general relativity is expressed in terms of Ashtekar variables, which represent gravitational fields in a way which reveals their similarity to electromagnetic fields and other gauge fields. The symmetries of general relativity can be formulated as constraints in terms of these variables. We verified the algebra of these constraints for gravitational waves. We used vectors to visually represent the constraints on a spacetime diagram in a manner that is consistent with their actions and their algebra. We represented the constraints as either a Lorentz boost, a directional shift, or a propagation along a light cone. Gravitational waves are oscillations in the geometry of spacetime caused by the movement of mass or energy. In the quantum theory, geometry is quantized so spatial quantities such as area and volume take on discrete values. We worked on quantizing plane gravitational waves, which propagate in one direction and have uniform wavefronts perpendicular to the direction of travel. We found possible quantum forms for the unidirectional constraint, the constraint that ensures the plane wave moves only in one direction. We checked for normalizable solutions satisfying the constraint.

Determining the Size and Structure of Dusty Tori in Active Galactic Nuclei

Bryanne McDonough

Active galactic nuclei (AGN) are luminous sources in the centers of some galaxies. They are powered by material in the accretion disk falling into the supermassive black hole. The accretion disk is surrounded by a torus of dusty clouds. Light emitted from the accretion disk is absorbed by the dusty torus which then emits its own light. By studying the response of the dusty torus to variations in the accretion disk emission, the size and structure of the torus can be determined.

Automation of a fluorescence microscopy based live cell imaging platform

Hannahmariam Mekbib

Fluorescence microscopy has enabled biologists to learn about the living cell and to study biological events such as cell signaling and gene expression for many years. In order to image live cells and probe the dynamics of fluorophores with high temporal resolution, imaging conditions must be set to an optimal compromise between phototoxicity, localization precision, photobleaching and temporal resolution. We present automation of a custom-made fluorescent microscope as an instrumentation technique to minimize these limiting factors. We developed a LabVIEW program to simultaneously control several electronics in our microscope setup including an Acousto Optic Tunable Filter (AOTF) which we will add to our setup to control the excitation source. The combination of these modifications will significantly decrease the exposure time by only exciting the fluorophores when they are being imaged which allows imaging live cells for longer periods of time. This project will not only enable live cell imaging but also allow additional modalities such as super resolution microscopy

Tracking Short-Term Variations in Titan`s Haze Distribution with SINFONI VLT

Fiona Nichols-Fleming

Titan is the only satellite in the solar system with a thick atmosphere, which is predominantly comprised of nitrogen and methane gas along with a hydrocarbon aerosol haze. The haze distribution throughout the atmosphere is the basis for many aerosol models which work to constrain the locations of organics across Titan. I present here a study of the haze distribution based on analysis of spectra from SINFONI VLT in both H+K bands acquired over a year during a broader cloud monitoring campaign run by Cornell. This analysis provides the best average of both spectral resolution and wavelength coverage, allowing for a more accurate knowledge of the location of organics. We found significant latitudinal variation in the monthly haze distribution, which suggests that there exists local influences on haze production that are currently not well understood.

Mechanics of blood flow into xenopus laevis tadpoles` lungs

Francine Nihozeko

In mammals, lungs become functional after birth, whereas they are functional right after metamorphosis in amphibians. The heart, on the other hand, is the first organ to develop in many vertebrate embryos. The heart is part of the circulatory system, which is necessary to transport nutrients and waste in the embryo. The cardiovascular and respiratory system are coupled. They work together to supply body tissues with fresh oxygen and to offload carbon dioxide produced during cellular respiration. Using a video frame analysis method and knowledge of fluid mechanics, this ongoing project examines blood flow into xenopus tadpoles' lungs, to see if there are any blood flow changes associated with the lung's function. As lungs become functional, pulmonary blood vessels expand and a non-allometric growth is expected.

Precision spectroscopy of neutral beryllium

Carson Patterson

The goal of my lab's research is to perform high precision spectroscopy on neutral beryllium. Currently, the precision of experimental measurements of several beryllium energy states lags behind that of theoretical estimates by more than an order of magnitude. Improved experimental measurements will provide critical feedback about theoretical predictions. My senior thesis project aims to measure two particularly weak transitions and the hyperfine splitting of these transitions through a two step ionization process.

The effects of lasing different crystals

Phoebe Pelzer

I would like to explain the differing effects that a specific laser has on crystals.

Improving Sensitivity in Scanning SQUID (Superconducting Quantum Interference Device) Microscopy using Resonance Frequency SQUIDs

Rachel Resnick

The device we currently use to do magnetic scanning is called a superconducting quantum interference devices (SQUID), and we use it with direct current (DC) measurements to create images of the magnetic properties of materials. The issues with these devices are their limited precision and the difficulty in fabricating them. There is another type of SQUID that works at microwave frequencies with ten times the precision of DC SQUIDs while being simpler to fabricate. The goal of my project is to characterize the SQUIDs that work at microwave frequency (RF SQUIDs) and find a way to incorporate them into one of the scanning systems in the lab.

Using Molière Radius to Determine Optimal Fine Grain Tracker Size

Samantha Tetef

I worked as part of the Deep Underground Neutrino Experiment (D.U.N.E.), Near Detector Task Force (N.D.T.F.) and used ART and ROOT to analyze data from Monte Carlo simulations to help determine the best design for the near detector. I focused on the fine grain tracker (FGT) design, specifically looking at whether changing the size of the detector affected the resolution of the two daughter photons of a neutral pion when both the photons hit the downstream ECAL. I mainly wrote fhicl modules to run on ROOT files created by Geant4 to create histograms in order to perform my analysis.

Precise Measurements of Indium 7P States Stark Shift Polarizabilities Using Two-Step Laser Spectroscopy

Bingyi Wang

We have made precise measurements of the indium 7P1/2 and 7P3/2 polarizabilities (scalar and tensor pieces) using two-step diode laser spectroscopy in an atomic beam. The technique of using two-step excitation along with AOM and EOMs result in desired signal-to-noise ratio while eliminating Doppler broadening. These new results are part of a series of indium polarizability measurements that started in our group many years ago. Our results agree with new ab initio calculations of these quantities, whose uncertainties are calculated using two high-precision relativistic methods. The experimental and theoretical results exhibit excellent agreement, and we can combine the results to infer several reduced dipole matrix elements in 115In. Recent measurements that significantly improve the precision of hyperfine structure constants in the indium 7p1/2 and 7p3/2 will also be discussed.

Investigating Lorentz Symmetry Breaking in Massive Gravity Theory and Possible Signatures in Matter Interactions

Yuewei Wen

The idea that gravitons might have a small mass opens up new possibilities for addressing important questions in cosmology and particle physics theories, such as the nature of dark energy and how gravity couples to the Standard Model. Recently significant progress was made when a theory known as dRGT massive gravity was constructed in a way that is free of unphysical ghost modes. However, the theory involves using a fixed background tensor that explicitly breaks diffeomorphisms and local Lorentz invariance. To include couplings with matter, an effective combination of the metric and the background is used. My research is aimed at investigating the mathematical properties of the background and its physical effects. This has involved learning how to perform field variations inside square-root operators, how to use a vierbein formalism to accommodate fermions, and how to incorporate the couplings with matter fields. As a work in progress, we ultimately hope to determine if bounds from a phenomenological framework known as the Standard-Model Extension can be used to place limits on the Lorentz-violating couplings between the background tensor and the matter fields.

High-Velocity Saturation in Graphene Encapsulated by Hexagonal Boron Nitride

Megan Yamoah

While mainly probed for its unique low-field electrical characteristics, graphene holds potential in practical device applications such as amplifiers or high-current interconnects. These applications rely on our understanding of the high electric field behavior and especially on our ability to minimize loss and maximize carrier velocities in graphene devices. Under high electric field, the drift velocity approaches a constant saturation velocity which can be limited by intrinsic or substrate phonons, heating, and substrate impurities. We present devices with graphene encapsulated by hexagonal boron nitride ( hBN) which, due in part to the superior thermal conductivity and low impurity density of the hBN/graphene interface, produces saturation velocities higher than on all other common graphene substrates to date and suggest that hBN substrate phonons are the primary limiting factor for saturation velocity in our devices.

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