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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.


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.

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.



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​



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.

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.


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.


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.


Student Research Archives


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