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Student Research at DePauw

Many DePauw physics majors have worked on research projects during the summer.  Opportunities for on campus research exist in the Science Research Fellows Program, the Faculty-Student Research Grants, or with individual faculty research grants.  A wide variety of off campus research opportunities is also available.  Some recent student research projects are described below.



Surveying Light Pollution in Greencastle, IN and Putnam County

Jacob Boudreau and Thomas Grier

Faculty sponsor: Prof. M. Kertzman, Dept. of Astronomy and Physics


Light pollution is a not a just a problem for astronomers! Studies show there are significant environmental, economic, and societal impacts from light pollution. The goal of our research is to develop procedures for studying light pollution locally, which consists of Putnam County, Greencastle, and DePauw’s campus. We hope to develop a long-term monitoring system to see how the ambient light in these locations are changing.

 Developing an Extended Duration Flight System for Studying Energetic Particles in the Stratosphere

Students:  Kobby Van Dyck and Zach Wilkerson

Faculty sponsor:   Howard Brooks; Dept. of Physics and Astronomy

Our atmosphere is bombarded with very energetic particles that travel great distances across our galaxy.  The maximum number of interactions between these particles and our atmosphere occur at a height of 20 kilometers above the Earth’s surface.  This altitude is not routinely accessible for extended time studies. Zach and Kobby are developing a detection system utilizing Geiger counters and a solar cell array that will be able to float in the maximum interaction region for many hours or perhaps even days.




Scattering of Liquid Droplets from Axisymmetric Targets

Jacob Boudreau, Tristan Stamets

Faculty Sponsor: Prof. Jacob Hale, Dept. of Physics and Astronomy, DePauw University

A droplet skirting across the surface of a bath can be seen as a particle moving through space. This analogue can be push further when a glass rod is partially submerged into the bath, creating a positive meniscus. The skirting droplet, which has a negative meniscus, interacts with the meniscus of the glass rod, causing the droplet to be deflected. This deflection is similar to Rutherford scattering. Nuclear scattering is caused by the positive electrostatic potential of the target nucleus and the positive potential of the alpha particle. In this case, the meniscus acts as the potential field. The goal of this research is to find the shape of the potential field for the glass rod. For electrostatic, the potential is defined as V=k q/r, where k is the field constant and the q is the charge of the particle. While the electrostatic potential is a 1/r; the potential field of the meniscus is surprisingly linear. This was found by analyzing the trajectories of the droplets and knowing the parameters of the run. The parameters found were the impact parameter, b, or how head-on the interaction is, the distance of closest approach, dmin, and the scattering angle, θ. The kinetic energy was also found. With these parameters and the tracked trajectories of the droplets, we were able to determine the potential field of the meniscus and the droplet to be linear.


Verifying Membership and Chemical Homogeneity in the Open Clusters NGC 2682 and NGC 6819

Thomas Grier

Faculty Sponsor: Prof. Peter Frinchaboy, Dept. of Physics and Astronomy, Texas Christian University

Using data from both the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and WIYN Open Cluster Study (WOCS), we wanted to have a better means of determining opencluster membership. By matching stars from both data sets via right ascension and declination, we were able to determine a cluster's radial velocity and metallicity and generate membership probabilities for all stars in both data sets. In the end, we were able to see if there were stars whose memberships were questionable and if stars had been missed in membership identification. We were also able to verify if the member stars truly show evidence for chemical homogeneity as expected for open clusters​


Discerning Alkyl Nitrate Abundance in Bakersfield, CA

Joshua Clark, Stacey Hughes, Don R. Blake

Faculty Sponsor: Dr. Don R. Blake, University of California-Irvine

During the 2016 summer NASA Student Airborne Research Program (SARP), the NASA DC-8 flew over Bakersfield, CA because it consistently ranks in the top three U.S. cities with the worst air quality. Analysis of whole air samples collected during the Bakersfield airport missed approach indicated elevated concentrations of alkyl nitrates (RONO2). It is imperative that we study the source of alkyl nitrates as they lead to nitrogen oxide (NOx), an ozone precursor. High alkane (RH) concentrations were also measured, indicating the alkyl nitrates were most likely photochemically produced. NOAA HYSPLIT was used to determine whether emissions were localized or transported and found to mostly originate in the San Joaquin Valley, which coincides with the calculated mean air mass age of about 19 ± 5 hours. However, the age varied greatly from 8 to 31 hours, which is indicative of local emissions as well. Based on i/n pentane ratios of 2.3 ± 0.6, it was estimated that the sources of the emissions are mostly urban. This is significant because a combination of aged and fresh pollution suggests that a more in-depth analysis of local emissions is needed and should be compared to the central valley emissions in an attempt to improve the air quality in Bakersfield.



Measuring the VHE Cosmic Ray Electron Spectrum with VERITAS

Joshua Clark

Faculty sponsor: Prof. Mary Kertzman, Dept. of Physics and Astronomy, DePauw University

Cosmic rays are relativistic charged particles that permeate our galaxy.  There are two possible components of cosmic rays: the nuclei of atoms (hadrons), or electrons.  The hadronic component is dominated by protons through nuclei of all chemical elements up to uranium have been detected.  Hadronic cosmic rays have been extensively studies, and their energy spectrum has been measured well past 100 TeV.  The electron spectrum, however, has only been measured at low energies.




Designing Environmental Control Systems for SPIM Microscopy

Nathaniel Smith, Seth Winfree, Dr. Kenneth Dunn

Faculty Sponsor: Dr. Kenneth Dunn, Dept. of Nephrology, Indiana University School of Medicine

The ability to test drug compounds inside the context of living cells is immensely important.  A simple, but impractical solution is to test drug compounds in fixed or cultured cells.  However, these cells generally lack the cell-cell and cell-cell matrix interactions seen in natural tissues.  In order to study tissue development in the presence of drug compounds, time-lapse studies must be conducted on naturalistic cell samples in order to see growth and change in the sample.  Naturalistic cell samples require systems to perfuse them with oxygen, nutrients, and remove waste just as a natural body would.  In these conditions, 3-dimensional imaging becomes necessary because plated cells do not maintain the same interactions as cells inside a living tissue.

Effect of Hyperthermia on SKBR-3 cells Intracellular vs. Membrane-Bound Magnetic Nanoparticle Hyperthermia

Caleb Akers, Frederik Soetaert, Mohammed Hedayati, Robert Ivkov

Faculty Sponsor: Frederik Soetaert, Dept. of Radiation Oncology, Johns Hopkins School of Medicine

Hyperthermia is a cancer treatment in which solid tumors are exposed to supra-physiological temperatures (42 deg C - 46 deg C) for a defined period of time.  Its use as a cancer treatment is motivated by the dual effect of causing direct cytotoxicity chemotherapies.  Magnetic Iron Oxide NanoParticles (MIONPs) are used to focus heating of cancer cells through the application of an alternating magnetic field (AMF).  The mechanism of energy transduction and effectiveness of varying the nanoparticle location (intacellular and membrane-bound) is unclear.  Reports suggest nanoparticle-mediated hyperthermia has potential to be more effective than other hyperthermia modalities.



Dynamics of Skirting Droplets

Caleb Akers

Faculty Sponsor: Prof. Jacob Hale, Dept. of Physics and Astronomy, DePauw University

Imagine a rain drop falling onto a pond. To the naked eye, it appears that the drop instantly joins the pond water, but high-speed imaging reveals the droplet sits on top of the pond for a brief, but finite time. The act of the droplet not joining the bulk fluid is referred to as non-coalescence. The accepted theory for this phenomenon is that a thin air film separates the droplet from the bulk until the film drains away. This phenomenon can be prolonged through adding surfactants to the solution, constantly oscillating the bath, or putting the droplet in relative motion with the bath. This study develops a quantitative analysis of the non-coalescence phenomenon with freely-moving, slowing droplets skirting across the water. The droplet slows exponentially and the decay constant appears to increase linearly with drop size. We also show that the droplet is likely rolling on top of the surface, rather than purely skirting, and might actually be “spinning-out” on the surface.

Very High-Energy Gamma-Rays Observations of IC 443

Quincy Abarr

Faculty sponsor: Prof. Mary Kertzman, Dept. of Physics and Astronomy, DePauw University

IC 443 is a Type II supernova remnant about 5000 light-years away in the constellation Gemini that exploded with the energy of 5*1029 atomic bombs. It is one of the best-studied supernova remnants because of its interesting environment; the shockwave from the supernova is expanding into two molecular clouds of two densities, causing its interesting appearance. Taking data collected by the Very Energetic Radiation Imaging Telescope Array System (VERITAS), we analyzed the gamma-ray emission of IC 443 to learn more about this interesting system.






Fluid Galilean Cannon

Brian Good

Faculty Sponsor: Prof. Jacob Hale, Dept. of Physics and Astronomy, DePauw University

Upon impact with a solid surface, a test tube filled with liquid forms a tall spout known as a Worthington jet.  This phenomenon depends on the curvature of the bottom of the tube as well as sufficient initial meniscus depth (a result of surface tension and the hydrophilic nature of the glass tube).  As the jet gets taller, surface tension causes spherical droplets to pinch off and eject at a greater velocity than the impact speed of the test tube.  By measuring the velocities and masses of these droplets, we aim to describe the behavior of Worthington jets in the context of momentum and energy transfer.  As a building block for this, we will first study similar properties of stacked Superballs, a system with discrete macroscopic components that might help describe the way individual fluid particles interact.

A Stratospheric Multiwavelength Photometer System

Elizabeth Hoover, Tao Qian

 Faculty Sponsor: Prof. Howard Brooks, Dept. of Physics and Astronomy, DePauw University

A multiwavelength photometer system has been designed to record the change in intensity of the radiation from the Sun with changes with altitude at seven different wavelengths. Light emitting diodes can serve as detectors for the operating color of the diode. This system uses a red, orange, green, blue, violet, ultraviolet, and two infrared LEDs to detect the seven different wavelengths with the output signals being processed by operational amplifiers.  The ratio of the intensity of the ultraviolet to the violet indicates the ozone abundance and the ratio of the two infrared wavelengths indicates the abundance of water vapor in the atmosphere.  The system also includes a compass and three-axis accelerometer to determine the orientation of the balloon as the data is recorded. The results are stored onboard during flight with an Arduino microcontroller. Construction details and results are presented. 

Observing Exoplanets Using CCD Photometry

Quin Abarr

Faculty Sponsor: Prof. Mary Kertzman, Dept. of Physics and Astronomy, DePauw University

As of October 13, 2013, 998 planets have been discovered which orbit stars other than our Sun; thousands more candidates exists which only have to be confirmed. These planets around other stars are called extrasolar planets, or exoplanets for short. Over the summer, I did research here at McKim Observatory to try to observe these planets. Some exoplanets are large, comparable in size to Jupiter. If the orbit of one of these planets brings it between Earth and its parents star, it blocks a little bit of the star’s light. While we can’t see the shape of the planet outlined within the view of the star, it is possible to observe the star dim by a very small fraction as the planet transits the star. This is what I attempted to observe and record using a CCD camera in an 11-inch Schmidt-Cassegrain telescope.





Non-Coalescing Liquid Drops in Motion

Drew Rohm-Ensing

 Faculty Sponsor: Prof. Jacob Hale, Dept. of Physics and Astronomy, DePauw University

If a drop of a surfactant solution is released from a significant height, it can rest on the surface of the bulk solution for long periods of time. Setting these drops into motion can lengthen their life-span. Using high-speed imaging and tracking software, we were able to image moving drops and build a model to describe and analyze how the size of the drop affected its life-span.

Electromagnetic Showers in Lead at Stratospheric Altitudes

Andres Adams, Ethan Brauer,  Jon Stroman

Faculty Sponsor: Prof. Howard Brooks, Dept. of Physics and Astronomy, DePauw University

Cosmic rays are constantly bombarding the atmosphere and creating energetic particles. When these particles interact with other matter they will either disintegrate and their energy will be absorbed by that matter, or, if they are sufficiently energetic, they will
convert into many less energetic particles. This is known as the showering effect. This is well documented and frequently studied at ground level. Our study differed in that we measure the occurrences of these showers at high altitude. We measure the particles using Geiger counters which are organized in a triangular array. The simultaneous
discharge of all three Geiger counters, known as a coincidence, indicates a shower event. Varying the amount of lead shielding placed above the Geiger counter array from zero to four centimeters, we sought to find the critical thickness at which the showering effect
was maximized. We found that 1cm of lead or more produced significantly more showers than thicknesses under 1cm. Logistical constraints prevented us from finding the critical thickness.

Using High-speed Imaging to Examine Thin Film Splashes through

the Momentum of Secondary Droplets

Quincy Abarr

Faculty Sponsor: Prof. Jacob Hale, Dept. of Physics and AstronomyDePauw University

When a liquid drop hits a thin film of liquid about as thick as the diameter of the drop, a coronal splash forms. From that crown, jets form which elongate and pinch off into smaller secondary droplets.  Using a high-speed video camera, we examined these secondary droplets to find their momentum, which helped us to better understand the interaction between a drop and a thin liquid film and the formation of the secondary droplets. We found that the two dominating forces in the interaction are the viscous and surface tension forces, both of which contribute approximately equally to the impulse on the drop by the thin film during their interaction.





Balloon-Assisted Stratospheric Experiments

Cloverdale High School Students: Colte Tomlinson,  Jessica Soto-Skeete, 

Mitchell Williams,  Angelica Manning 

Faculty Sponsor: Prof. Howard Brooks, Dept. of Physics and Astronomy, DePauw University Bridge2Science Program

Utilizing a helium-filled balloon as a launch vehicle, a variety of small lightweight research experiments were carried into the middle portion of the stratosphere, up to 100,000 feet above sea level, to learn more about this neglected region of near space. The experiments included radiation sensors and electronic orientation sensors.   We obtained video images from throughout the flight. Data from the experiments was compared to other experimentally known and/or theoretically predicted results.





Infrared to Ultraviolet Doubling Cavity Design

Jonathan Cripe

Faculty Sponsor: Prof. John Caraher, Dept. of Physics and Astronomy, DePauw University

Second-Harmonic Generation (SHG) is a nonlinear optical process whereby photon pairs of one frequency combine to form single photons at twice the frequency. The efficiency of this process is proportional to the intensity of the original photon beam, and is generally quite low for incident laser intensities attainable in a single pass of a continuous-wave laser. Efficient doubling requires both focusing into the medium where doubling occurs and enhancement of optical power by trapping light in traveling wave cavity. This project involved designing and beginning to build such a cavity for use in experiments on absorption of entangled photon pairs. We describe the design of the cavity, which required Gaussian optics both to characterize the circulating beam and to ensure the input light had an intensity profile conducive to efficient capture inside the cavity.

Locking a Diode Laser to a Two-Photon Atomic Transition

Ashwin Upasani

Faculty Sponsor:  Prof. John Caraher, Department of Physics and Astronomy, DePauw University

Our project aims at using a Diode Laser and a Rubidium cell to observe and study two-photon
absorption of the Rb atoms. The process presents various challenges like stability, temperature variation, laser feedback, availability of photons, etc. We aimed to produce a stable experimental setup that would consistently perform the task of two-photon absorption allowing us to study spectroscopy for Rubidium. Furthermore, we also had a goal of locking the diode laser at the resonant frequency which would help our setup in terms of stability and consistency. When the laser is locked to a two-photon atomic transition, the same wavelength of light would have applications in entangled two-photon absorption. Entangled two-photon
absorption would be studied for Rb.


Cosmic Radiation Testing in the Stratosphere

Ruizhe Ma, Mark Tolley

Faculty Sponsor: Prof. Howard Brooks, Dept. of Physics and Astronomy, DePauw University

The Balloon Assisted Stratospheric Experiments (BASE) program aims to conduct high altitude physics experiments carried aloft by helium filled latex balloons. Our project this summer aims to measure cosmic activities in the atmosphere using Geiger counters. The data collected by Geiger counters from flights have shown an increase of counts per minute of energetic particles as the altitude increases, and a decrease of count rate after reaching a critical altitude, known as the Pfotzer Maximum [1]. This result confirms the mechanism of the formation of energetic particles produced by cosmic rays. We have also covered the counters with different thicknesses of lead and have hypothesized that lead shielding will decrease the count rate. The data collected on the ground have shown a decrease of count rate due to the shielding. However, the data collected in atmospheric runs have shown an increase in count rate with the presence of lead shield. We suspect that the cosmic rays and the particles produced by cosmic rays in the stratosphere are sufficiently energetic to produce more particles when they hit the lead shield [2]. Also, the geometry of the lead shield around the Geiger counter affects the number of counts determined by the volume enclosed.

Effects of Downconverted Photon Spectra on Virtual State Spectroscopy

Yujiao Qin

Faculty Sponsor: Prof. John Caraher, Dept. of Physics and Astronomy, DePauw University

The proposed technique known as Virtual State Spectroscopy relies on modulations in the two-photon absorption probability through the manipulation of temporal correlations of the photon pair. Theoretical treatments of this process to date have assumed the paired photons have identical energies that sum to a consistent total energy. In the lab, however, the spontaneous parametric downconversion process that gives birth to these entangled photon pairs results in photons with a wide range of frequencies (with a spread of perhaps 20 nm about a central wavelength of 800 nm), violating the assumption of equal energies. Moreover, many experiments use broadband ultrafast lasers to pump the downconversion crystal, resulting in comparably large spread in the total energies of different photon pairs. This violates the assumption that every pair has the same total energy.
Our work explores of how these spectral properties of both pump and downconverted photons affect the cross-section modulations. Using numerical simulations based on second-order time-dependent perturbation theory, we look at the deviation of cross-section modulation from the simple model of degenerate (i.e. equal energy) photons, both for the atomic hydrogen and for rubidium.



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