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- 2016 REU Projects

- Astronomy and Astrophysics
- Nuclear Astrophysics
- Nuclear Theory
- Materials Science and Surface Physics
- Physics Education Research
- Computational Physics
- Mathematical Physics

**Astronomy & Astrophysics – Prof. Kurtis A. Williams**

**Email:** **Kurtis.Williams@tamuc.edu
**

**Research Overview:**

Prof. Williams studies white dwarfs, the slowly fading embers of stars that have exhausted their nuclear fuel. His research involves optical and ultraviolet observations of white dwarf stars. This research is currently funded by a Research Corporation Cottrell College Science Grant. Over the past five years, Dr. Williams has mentored seven REU students. Two of these students’ work has already been published in leading astrophysical research journals, and two more papers involving other REU students are underway.

**Projects for REU students:**

Students, in conjunction with Dr. Williams, will select one of the following projects that suits their interest and abilities:

1. Looking for star spots on white dwarfs. Some white dwarfs have strong magnetic fields that could generate star spots (similar to sunspots) on their surfaces. White dwarfs can rotate, and as spots come into view and go out of view, the white dwarfs vary in brightness. We will be looking for evidence of star spots and rotation in a selection of peculiar white dwarfs. If we find spots, we will measure the rotation period of these white dwarfs with the long term goal of determining how quickly these stars’ rotation slows as the star’s magnetic field interacts with interstellar magnetic fields.

2. Characterization of suspected cataclysmic variables. Cataclysmic variables are a type of binary star where the white dwarf remnant of a now-deceased star is able to accrete material from a close companion star. Ongoing searches for supernovae and other variable stars continually discover many cataclysmic variables, but most of these are not studied in any further detail. We will select some of these newly discovered objects for follow-up observations and determine how their light output changes with time. This will allow us to classify each cataclysmic variable and determine if any systems need further observations.

3. Timing of exoplanet transits. From our viewpoint on the Earth, a small fraction of planets around other stars will pass in front of their parent star each orbit. The planet blocks a tiny amount of the star’s light, causing the star to dim slightly; this is called a transit. If there is a second planet in the planetary system, its gravity can change the exact times of the first planet’s transit. By studying the times of transits, astronomers can potentially detect planets that we otherwise would not know about. We will select a small sample of exoplanets that are observable over the program and look for evidence of transit timing variations with a goal of determining the mass and orbit of other planets in an exoplanetary system

**What Students Will Do:**

Students will read journal articles from astronomical literature to understand the science behind each project, the analysis techniques we will use, and the goals of their projects. Students will learn how to take high-quality data with telescopes, including the SARA telescopes and A&M-Commerce telescopes. Students will learn the basics of data reduction, or how raw images and calibrations are turned into scientifically useful information. From the data the students collect along with some previously taken data, each student will produce a light curve for the object of interest. We will then model the light curves to determine the desired properties of each target. Students will write a journal-quality paper on their findings, and we will submit these papers to an appropriate venue for publication (the exact venue depends on the findings of the project). Over the course of this project, students will learn how to use multiple pieces of software installed on computers with differing operating systems to analyze astronomical data. Students will also gain some basic understanding of statistics and research ethics. All students will practice the conveying of scientific information in both verbal and written contexts.

**Astronomy and Astrophysics - Prof. Kent Montgomery**

**Email:** **Kent.Montgomery@tamuc.edu**

**Web site: tamuc.edu/physics**

**Phone: 903-468-8650**

**Research Overview:**

Prof. Kent Montgomery studies asteroid light-curves. Over twelve undergraduates have participated in research in his lab in the past six years and during this time 6 journal papers have been published.

**Project for REU student:**

The main objective of the proposed project is to analyze specific asteroids to determine how their brightness varies with time. This variation in brightness can then be used to determine the asteroid’s rotation period and shape.

**What the Student Will Do:**

The student will read some background papers to understand the techniques, and ramifications of the proposed research. The student will then learn how to take astronomical data using both the telescopes of the SARA consortium and the A&M-Commerce telescopes. The students will learn how to run the telescopes, collect and analyze data and how to collect the necessary calibration images required each night. The students will then spend numerous nights collecting astronomical images as they watch the asteroid all night long. After the data has been collected the student will reduce the raw images to create images which can then be analyzed. The students will then extract the brightness of the asteroid from each of these images. Plotting the brightness versus time will produce a light-curve for the asteroid. The light-curve is then analyzed to determine the rotation period of the asteroid and the shape of the light-curve is used to determine the shape of the asteroid. By the end of the study the student will have studied 3 to 5 asteroids and will write a paper on the research findings to be published in the Minor Planet Bulletin.

**Astronomy and Astrophysics - Prof. Matt Wood**

**Email:** **Matt.Wood@tamuc.edu**

**Web site:** **http://faculty.tamuc.edu/mwood/**

**Phone: 903-886-5487**

**Research Overview:**

Prof. Wood and his group study the close interacting binary systems known as cataclysmic variables. Containing a main-sequence star losing mass to a white dwarf star, these systems are observed to display a wide variety of variability from classical nova outbursts, to disk oscillations known as superhumps, to smaller dwarf nova outbursts and flickering behavior. Wood’s group studies cataclysmic variables through both observational and numerical means.

**Project for REU Student:**

The REU student may either analyze existing large multi-site data sets either from the professional-amateur collaboration Center for Backyard Astrophysics or the NASA Kepler Mission. The student will also be taking and analyzing data using our campus telescope and/or one or more of the three 1-m class SARA telescopes (saraobservatory.org) located at premier observing sites around the globe. Alternatively, the student who is interested in numerical astrophysics may choose to model accretion disk dynamics using our smoothed particle hydrodynamics code.

**What the Student Will Do:**

The student will read the literature provided to learn the field of cataclysmic variables and astrophysical motivation for the proposed research. The student pursuing an observational project will learn how to obtain time series data using our telescopes, including the required calibration images. The student will learn how to reduce the data to obtain a time series file ("light curve") containing times and measured brightnesses, and then how to analyze these data to obtain the Fourier transforms (indicating periods present), average pulse shapes, O-C phase diagrams, etc. The student will write a paper and present his or her results orally by the end of the program. A theoretical student will spend his or her time learning the methods of numerical simulation and then developing and running codes to simulate the dynamics of accretion disks or related phenomena.

**Physics Education Research – Professor Robynne Lock**

**Email:** **robynne.lock@tamuc.edu**

**Webs site:** **tamuc.edu/physics**

**Phone: 903-886-8767**

**Research Overview:**

Prof. Lock’s research focuses on identifying and understanding methods to improve all students’ attitudes about physics and to encourage more students to pursue physics careers. In particular, we seek to find ways to reduce the gender gap. Only about 7,000 physics bachelor’s degrees are earned in the U.S. each year, and, currently, only about 1/5 of those bachelor’s degrees in physics are earned by women. We use a physics identity framework in our work to understand how students make their initial career decisions at the end of high school and the beginning of college. We use quantitative methods to find what is broadly applicable and qualitative methods to understand the mechanisms of how successful strategies work.

**Project for REU student:**

The main objective of the proposed project is to determine the impact of studio physics on physics identity and physics career choice. Studio physics is a student-centered learning environment in which the majority of class time is spent on group activities rather than lecture. While studio physics has been demonstrated to improve conceptual understanding and problem-solving abilities, its impact on physics identity has not yet been explored.

**What the Student Will Do:**

The student will be involved in analyzing both quantitative and qualitative data collected in introductory physics classes during the previous two academic years. The student will conduct t-tests (using R) to examine changes in physics identity and conceptual understanding over the course of each semester. Additionally, the student will analyze video recordings of studio classes and student interviews (MaxQDA or Transana). Whether the emphasis is on quantitative or qualitative analysis will depend on the students’ interests and skills. The student will read relevant research literature over the course of the summer and work closely with Prof. Lock. The student will write a final report and give an oral presentation.

**Nuclear Theory and Astrophysics - Prof. Bao-An Li**

**Email:** **Bao-An.Li@tamuc.edu**

**Web site:** **http://scholar.google.com/citations?user=-0gnvt4AAAAJ&hl=en**

**Phone: 903-886-5486**

**Research Overview:**

Prof. Li’s group works in the multi-disciplinary area of nuclear physics, computational physics and astrophysics. The current focus of the group is to investigate the Equation of State (EOS) of dense neutron-rich nuclear matter formed in nuclear reactions and which may also exist naturally in compact stars. The explosion mechanism of supernovae, structure and evolution of neutron stars, the emission of gravitational waves from several possible sources, and the dynamics of terrestrial nuclear reactions all depend on the EOS. However, our current knowledge about the EOS of dense neutron-rich matter is still very poor. Its determination has been a common thrust of several operating and/or planned x-ray satellites as well as advanced new radioactive beam facilities being built around the world. Currently funded by the National Science Foundation (NSF) and the Department of Energy (DOE), the group has been developing tools for investigating several critical issues about the EOS of dense neutron-rich matter. The group has productive collaborations with several experimental groups both in the USA and abroad. During the last few years, 6 REU students have collaborated with Prof. Li and his colleagues in addressing some of the most interesting problems in this field leading to 5 publications with REU students as co-authors in top physics and astronomy journals.

**Project for REU Student:**

**Effects of nucleon effective-mass on nuclear reactions in neutron-rich matter**

We have several projects appropriate for the REU students to work on during the 10-weeks program each summer. For example, one student can investigate effects of the nucleon effective mass on nuclear reactions induced by radioactive beams using a newly developed transport model. Due to the Pauli blocking in nuclear medium and the finite-range of nuclear interactions, the effective masses of neutrons and protons in dense medium are expected to be different from their values in free space. Moreover, how they may depend on the neutron-richness of the medium is currently a hotly debated question and the answer affects significantly the extraction of nuclear EOS from nuclear reactions.

**What the Student Will Do:**

Using a transport simulation code developed by Prof. Li and his collaborators, the REU student will study effects of different nucleon effective masses on the temperature and density reached during nuclear reactions as well as the final experimental observables. Comparison with experimental data may allow us to put a constraint on the in-medium nucleon effective mass, its dependence on the neutron-richness of the medium and its effects on the extraction of the nuclear Equation of State. The student will first learn the basic physics of the Boltzmann transport equation in an undergraduate textbook on statistical physics and learn how to use a user-friendly transport model on a Linux computer. Then, the student will learn how to use several mathematical and graphical tools to analyze results of transport model simulations. After reproducing several previous results, the students will learn how to modify a subroutine where the nucleon effective mass is used and the associated physics. Using several values of the nucleon effective mass spanning the current uncertainty range of theoretical model predictions, the REU student will investigate how the variation of the input nucleon effective mass may affect the dynamics and experimental observables of nuclear reactions. By comparing the results of transport model simulations with available experimental data, we expect to put on a constraint on the nucleon effective mass in neutron-rich matter. Using the last 2 weeks of the REU program, the student will sum up his/her studies in a research report which may be turned into a publication in a physics journal.

**Nuclear Theory and Astrophysics - Prof. Carlos Bertulani**

**Email:** **Carlos.Bertulani@tamuc.edu**

**Web site:** **http://faculty.tamuc.edu/cbertulani/**

**Phone: 903-886-5882**

**Research Overview:**

Carlos Bertulani works on nuclear physics and nuclear astrophysics. He has mentored several PhD and MS students, written several textbooks for undergraduate and graduate students, published numerous papers in peer-reviewed journals and frequently organizes national and international conferences. He is currently the chair of the Committee on Education of the American Physical Society.

**Project for REU student:**

The goal of the project will be to improve our knowledge of radiative capture reactions in stars. In radiative capture reactions, a neutron, a proton, or an alpha-particle (helium) is captured by a nucleus and a photon is emitted. There are thousands of such reactions occurring in different stellar sites. They are responsible for the energy generation in stars and the formation of elements in the universe.

**What the Student Will Do:**

The student will start by reading the basics of the quantum mechanics used in describing reactions in stars and their use in reaction networks. The student will learn how to run and obtain results with a computer code for the purpose of calculating cross sections for radiative capture. Then the student will learn how to collect pertinent experimental data from the literature. Several nuclear potentials and fine-tuning of the nuclear bound and continuum states enter in the calculation strategies which will be used to try to explain the experimental data collected. It is expected that the work will lead to a publication at the end of the project. Depending on the quality of the work, the article might be published in a peer-reviewed scientific journal.

**Nuclear Theory and Astrophysics - Prof. William G. Newton**

**Email:** **William.Newton@tamuc.edu**

**Web site:** **https://williamnewton.wordpress.com/**

**Phone: 903-886-5487**

**Research Overview:**

Prof. William Newton's research focuses on the nuclear physics of neutron stars, the densest

known objects in the universe, with gravitational fields only exceeded by black holes. His research focuses on using observations of neutron stars to constrain the exotic properties of super-dense matter and the interaction between neutrons and protons (still relatively poorly known). He is also interested in using nuclear experiments to constrain the behavior of neutron

stars in a variety of astrophysical scenarios, including magnetars (neutron stars with colossal

magnetic fields) and X-ray binaries (neutron stars accreting material off of an ordinary companion star).

**Project for REU student:**

There is growing observational evidence that one of the most famous neutron stars, the Crab pulsar that lies at the heart of the beautiful Crab nebula, was formed in a relatively unusual type of supernova, that results from the collapse of a star with a core made of Oxygen, Neon and Magnesium. Such a supernova results in a neutron star with a specific mass, between 1.2 and 1.3 times the mass of our Sun. Given that mass, we can predict other observational properties of the Crab pulsar, including how fast it is cooling and how it's spin period is changing. The project will be to obtain predictions for these properties and compare with the observed properties of the Crab pulsar.

**What the Student Will Do:**

During the first week the students will familiarize themselves with the context: the different stellar evolution scenarios that lead to the production of a neutron star, the properties of neutron stars and the variety of physics we can learn from them. The student will use a number of different codes written in FORTRAN to compute the cooling rate and spin evolution of the crab pulsar. These results will be analyzed and plotted using Python codes developed by the REU student. The student will explore the literature on the Crab pulsar to obtain the latest measured properties and compare them with the outcome of our simulations. The student will assess whether these calculations are consistent with the currently favored stellar evolution scenario.

The student will also explore the literature to find other properties of the Crab pulsar that we might be able to estimate in the time available, and begin to develop codes to calculate them. In the final 2 weeks, the student will spend 50% of the time to prepare a final report of the research.