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.
SUMMER 2009 STUDENT RESEARCH PROJECTS
Analyzing VERITAS Observations of High-Energy Gamma Ray Sources: A Comparison of the Ring Background Model with the Maximum Likelihood Method
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.
SUMMER 2008 STUDENT RESEARCH PROJECT
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
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
Michelle Whitehead and Shelby Vorndran
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.
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