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Student Research Archives


 Analyzing VERITAS Observations of High-Energy Gamma Ray Sources:  A Comparison of the Ring Background Model with the Maximum Likelihood Method (On Campus Research)

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

Akanksha Cruczynski Chawla

VERITAS is a ground-based gamma ray observatory set in Arizona, comprising of a four-telescope array that gathers both gamma ray and cosmic ray events, with electronic detectors that reconstruct the collected data for analytic perusal.  We have used data from sources both strong and weak as well as those in different stages of flaring and quiescence to compare two methods for data analysis.  In every case, we have found the Maximum Likelihood Method to yield a higher significance of gamma ray detection as opposed to the Ring Background Model, deeming the former the more sensitive and sophisticated of the two alternatives.


 Anti-Neutrino Correlation in Neutron Decay(On Campus Research)

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Kaitrin Higbee, Michelle Whitehead

The standard model is the model that explains the fundamental forces and particles that make up the universe.  It was invented by theorists and needs to be proven by experimental methods.  Our experiment seeks to examine one of the parameters of the standard model in more detail.  Specifically our experiment works with one of the four fundamental forces, the weak nuclear force, and one of the parameters within the weak force.  This parameter is called "little a", also known as the electron anti-neutrino correlation coefficient.  Our experiment is called aCORN, which stands for "little a" correlation of neutron decay.

NDTGamma - Measuring Neutron Depolarization in Heavy Water(On Campus Research)

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Michelle Whitehead, Kaitrin Higbee

This experiment examines the possibility of doing another experiment aimed at testing a model for weak interactions in the nucleus.  This model was invented by theorists in 1980 and needs data to determine its validity.  NDTGamma - the name of the experiment that will test this model - involves a reaction of neutrons and deuterium nuclei producing tritium and gamma rays or n+D_2.0-->T_20+gamma.  NDTGamma will look for the smoking gun of the weak nuclear force: parity violation.  Parity mirror image of that experiment.  To do this measurement it is necessary to use polarized neutrons - a collection of neutrons spinning in the same directions.  Additionally, these neutrons must maintain their polarization up to the moment that they interact with the deuterium nucleus.  This work is directed at determining how well the neutrons keep their spin direction while interacting with deuterium in the form of heavy water.


Daniel Bennett

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University (On Campus Research)

Even though the neutron is neutral, it is made up of three quarks with discrete charges (+1/3, +1/3, and -2/3).  The neutron electric dipole moment (nEDM) is the measurement of how these charges are distributed within the neutron.  So far, no nEDM has been found, but we have lowered the upper limit through each successive experiment.  A non-zero nEDM has implications in cosmology, symmetries of the universe, and the Standard Model of physics.  My work this summer at Duke was with a group attempting the lower the experimental upper limit from 2.6 x 10-26 e-cm to 10-28 e-cm.

   Sky polarization and Compass Tilt Angle (On Campus Research)

Hao Li

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

My focus of the summer research with BASE (Balloon Associated Stratospheric Experiments) is on sky polarization.  The blue sky, like many other things around us, scatters polarized light.  Light consists of an electromagnetic wave with a certain orientation, the polarization.  The polarization is always perpendicular to the light path itself.  If just a single polarization direction is present in the light, the light is said to be linearly polarized.  The blue sky, for example, polarizes the light tangentially with respect to the sun, and causes a linear polarization which is largest about 90 degrees away from the sun.

My research is about how to measure how the sky polarization during the balloon launch varies with latitude, time and sun position etc.  I placed three phototransistors on one side of the pod perpendicular to the side wall.  One of the transistors is covered with a vertically polarized filter, another is covered with a horizontal filter, and the last one uncovered.  In order to make my measurements accurately, I also need to introduce the compass and tilt angle technology.  The compass can tell me which direction the transistors are facing and the tilt angle allows me to make adjustment of vertical and horizontal angle of the polarization data by doing some trigonometric calculations.

We have successfully made five balloon launches during the summer with polarized light via phototransistors in all flights; we added tilt sensors in four of five launches and compass three of five launches.  Most the data we got are within the scope.  However, the vertical polarization data exceeded our reference data (the uncovered transistor), which should not happen.

 NPDGamma- Neutron Depolarization (On Campus Research)

Michelle Whitehead and Shelby Vorndran

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

Nature likes symmetry.  Most of the time.  Electricity/magnetism, gravity, and the strong force all behave identically in a mirror as they do in reality.  But in the weak force, this concept is not true…and our experiment is working toward understanding this.  The goal of our summer research is to ensure that a larger experiment is feasible.  The ultimate experiment (NPDGamma) seeks to measure this asymmetry by observing neutron behavior.  In order to measure the asymmetry, neutrons must maintain a constant angular momentum, or “spin”.  We are trying to make sure that happens.


"Investigating the Range of Flight of a Kicked Football" (On Campus Research)

Jeremy Alland, Evan Dickerson, Jeff Tienes, Nicholas Vetz

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

Abstract: In 1999 the NFL implemented a standardization of kicking balls, requiring 12 new footballs, each distinguishable by the marking of a ‘K’, to be used for all game time kicks. In doing so, the controversy of variably worn footballs correlating to different flight ranges became nullified. However, the standardization of the weather conditions and other variables is impossible. Potentially, temperature, pressure, placement of the football on the kicking tee, and launch angle are all variables that can alter range. A greater understanding of these slight changes can provide one team an advantage over the other. In the experiment presented here, a kicking machine was constructed of springs, steel rods, and an aluminum foot and was used for all trials. A combination of the potential energy converted into kinetic energy by the springs and the transfer of momentum from the accelerated foot and leg into the football propelled the designated ball from the tee, providing a quantifiable range. Three significant results were found evident after the trials were run: 1) surprisingly, pressures ranging from 26-5psi exhibited little variation in the range of the kicked footballs; 2) for the trials varying temperature, a 10% decrease in range was observed from the room temperature to the -17.0 °C balls; 3) the same effect was shown in the variable football wear trials. The new balls went 10% shorter than the weathered balls. An in depth analysis of the experiment and results of the kick and flight mechanics of a football are presented.









"Beta Collimator Design Project for "a" Measurement in Free Neutron Beta Decay" (On Campus Research)

Aung Kyaw Sint

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Abstract: Neutron decay has been studied in the past century and several coefficients related to this process have been determined recently. One of these coefficients is called little "a" and is related to the probability that the anti-neutrino and electron from a neutron decay have the same general direction. The previous measurements of "a" contain a total error of about 4%1,2. An experiment that employs a novel method (see figure 1 in the poster) of measuring this coefficient is now being built3. This new design will reduce the error to less than 1%, allowing us to test the current prediction made by the Standard Model more precisely. The immediate goal of this project is to design electron collimators that will minimize electrons that scatter from the collimator into the electron detector. These events, left unchecked, will cause a large systematic error in "a".

References: 1Byrne et al., Journal of Physics G, 28, 1325 (2002). 2Stratowa et al., Physical Review D, 18, 3970 (1978). 3Wietfeldt et al., submitted to Nuclear Instruments and Methods A.




"Electron Collimator Design for the Little "a" Measurement" (On Campus Research)

Travis Clark

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Abstract: The Electron Collimator Ring (ECR) Project at DUNPL is a part of a larger project aimed at determining, in the free beta decay of a neutron, the direction of an anti-neutrino relative to the directions of the proton and electron with greater accuracy. The relative direction of the anti-neutrino will be inferred indirectly by measuring the electron and proton velocities with respective detectors and by timing the detection interval. The Electron Collimator Rings are designed to remove electrons from the experiment which will not yield accurate measurements. The goal of the ECR Project is to find the best geometry-material combination for the design of the rings.




"Polarimeter Construction for Measuring the Depolarization of Neutrons in Deuterium" (On Campus Research)

Matt Bowers

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Abstract: Each of the fundamental forces has constants associated with its strength. One of the constants for the weak force is the p.meson-coupling coefficient. There is a proposed experiment to measure this constant using deuterium capturing polarized neutrons to make tritium and polarized gamma rays. The calculation of the p.meson-coupling coefficient requires that the neutrons be polarized when they are captured. Unfortunately, the capture process is not very efficient so there is a possibility that before it is captured the neutron will lose its polarization. The degree of neutron polarization can be measured by passing the polarized gamma rays through devices containing polarized electrons in the form of magnetized metal. Two of these devices, called polarimeters (POL), have been built and initial tests have been performed.


"Constructing an Analog Digital Converter to Measure Neutron Depolarization in Deuterium" (On Campus Research)

Aung Kyaw Sint

Faculty Sponsor: Prof. Alexander Komives, Dept. of Physics and Astronomy, DePauw University

Abstract: In order to determine the p. weak meson coupling constant, neutrons will need to maintain a significant amount of their polarization when captured by the deuterium. Neutron capture in deuterium is not very efficient and the neutrons will bounce' around considerably before merging with a deuterium nucleus. Each "bounce" provides a significant opportunity for neutron depolarization. If too many neutrons are depolarized, the experiment won't be practical to perform. In order to measure the polarization, we need to construct a device that enables us to determine the polarization of gammas, which in turn will lead us to determine the polarization of neutrons. Part of the data acquisition system includes the ADC.


"CCD Photometry of DY Pegasi and HD333933" (On Campus Research)

Leslie Moore, Sara Baughman

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

Abstract: In 1989 the European Space Agency launched the Hipparcos satellite, carrying Tycho, a photometric instrument, which collected data for over a million stars. Some of these stars were identified as possibly being variable stars. However, further research is needed to confirm the variability of these stars. The purpose of our research was to determine whether or not one of these suspected variable stars, HD 333933, is actually variable. Before collecting data on HD 333933, we collected data for a known variable star, DY Pegasi, to refine our methods.


"Potential Function of Silicon Monoxide" (On Campus Research)

Alaska Subedi,

Faculty Sponsor: Prof. Fumika Kiriyama

Abstract: The detection of silicon monoxide (SiO) in the interstellar medium was first reported by Wilson et al. (1971) in its microwave emission. Since then SiO has been detected in over 200 stellar sources and shown to be an ubiquitous inhabitant of the universe. Understanding SiO is very important in fields such as astrophysics and atmospheric science. Therefore, comprehending the fundamental properties of especially the most abundant isotope SiO is significant to better understanding of various astrophysical phenomena. The focus of this work is to find the potential function of SiO, which would provide necessary foundation on evaluation its wave function and dipole moment function.


"Construction of a Robotic Solar Telescope" (On Campus Research)

Heather Byars, Andy Smith

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

Abstract: The Department of Physics and Astronomy proposed the addition of a Solar Observatory on the roof of Julian that would provide a real time display of the Sun, both in white light and H-alpha filtered, in the atrium of the renovated Julian Science and Mathematics Center. The Solar Observatory would consist of two refracting telescopes, which operating in a siderostat configuration [where a single mirror is turned to follow the Sun while the telescope remains pointed toward the celestial pole (Figure 4)], enclosed in a housing structure form the Julian roof on top of the penthouse. The telescopes could continuously observe the sun during the daylight hours in Greencastle, Indiana.

The telescopes would be controlled form a computer located in Room 402. The computer would control the opening and closing of the housing over the siderostat mirrors and automatically adjust the tilt of the mirror to compensate for the changing declination of the sun. The images would be transmitted via the Internet and displayed on flat screen computer monitors in display cases in the northwest corner of the first floor Julian atrium.


"Control System for the Gas Jet Target Recirculator at TUNL" (Off Campus Research)

Adam Shields

Abstract: The gas jet target in use at the Triangle Universities Nuclear Lab (TUNL) allows to be performed with fewer contaminants and more precision than other types of accelerator targets. However, the high volume of gas flow requires a recirculation system in order to make experiments feasible. The purpose of this project was to design and implement a control system for this recirculator. For more details, refer to the accompanying Control System Operations Manual.



National Radio Astronomy Observatory, GreenBank, WV (Off Campus Research)

Tammy Kjonaas

Tammy worked for the National Radio Astronomy Observatory. She was located at the observatory in Green Bank, West Virginia, but also traveled to and worked with data from the Very Large Array in New Mexico. She worked on data analysis for a 3He search in planetary nebulae with Dana Balser. She also got to use the Green Bank Telescope, the world’s largest moveable telescope. Her project was an REU, funded by the NSF.


Los Alamos National Lab, New Mexico (Off Campus Research)

Tim Tharp

Last summer I made a simulation using C++ to model particles scattering off of a Yukawa/Debye potential. From this simulation, I could calculate the momentum transfer cross section of a given plasma. This quantity is used by many people to calculate observible qualities such as conductivity or thermal relaxation of a plasma. Usually, the Standard Coulomb Logarithm Approximation is used to analytically calculate the cross section. This is an approximation, however, and physicists are unsure as to how correct it is in plasmas that haven't been tested. The simulation calculates the actual values for the cross section and can be used to check to see if the Coulomb Logarithm Approximation is close to correct or not for unfamiliar plasmas. Preliminary results indicate that fairly significant errors may occur for certain types of interesting plasma.



Lucas Synder ('02) (Off Campus Research)

I participated in an REU program at Michigan State University. I identified double-mode RR Lyrae stars of the Draco Dwarf Spheroidal Galaxy. With data obtained over a two year period from the US Naval Observatory in Flagstaff and the Wyoming Infra-Red Observatory, I used Fourier Transform programs to find the characteristic periods of 10 previously known and 16 new RRd stars.


Tim Tharp ('03) (Off Campus Research)

I worked at the Thomas Jefferson National Accelerator Facility in Newport News, VA. My work was mainly programming to help with the Data Acquisition systems for one of the main research halls. The hall was trying to measure the charge distribution of the neutron. My work involved two major components. The first was developing a system to remotely perform a hardwire reboot to computers in high radiation areas. The second was to make a real-time display of the rates of photomultiplier tubes used in the neutron detector.


Tammy Kjonaas ('03) (On Campus Research)

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

I worked on campus with Dr. Kertzman. We worked on the analysis of data from the Whipple Gamma Ray Telescope. I analyzed data on the Crab Nebula to test our version of the analysis code. I studied how the stability of the event rate depended on various cuts and data clean up procedures. I wrote versions of the graphical result display to run in PAW, and I worked on testing the algorithms for extended source analysis.


Adam Shields ('04) (On Campus Research)

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

I worked on campus with Dr. Brooks and Andy Smith trying to improve ART: The Automated 'Rang Thrower. First we were trying to devise a better way to take data. Tammy's year they just did it was observers, we wanted to get the flight on camera and take data from that. This involved figuring out how to set up the cameras, lighting, location, etc. Another big portion of the summer was spent developing a way to translate the boomerangs location from the video to the actual location, because video can only be seen two dimensionally, obviously, and this distorts the image slightly. Finally, we were just working on ART trying to make him throw more consistently with our personally designed booms, as opposed to the commercial ones used last summer. In the end ART pretty much underwent a total overhaul, but is much improved.



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