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MIT Graduate Physics Program
Prompt: Statement of Purpose – describe your research interests, including research you have
completed and or any papers you have published. Include your career objectives and goals for
graduate school. (Note to instructor: This prompt is actually a prompt from UCI’s Chemistry
department. MIT and Caltech required that I submit transcripts and CVs before I could have
access to their respective prompts.)
As a young Chicano from Long Beach, CA, focus on education was a way out of the ties
of crime and debauchery of the city. Gun shots, car screeches, and the smell of hallucinogenic
smoke was the type of environment that surrounded my study sessions – a sort of background
noise. Once I started attending college, the only background noise I heard was that of the
electronic equipment in the physics laboratories. This was soothing because I knew that I was
close to leaving the old environment behind, and in fact, I was excelling in my studies semester
after semester. Attending MIT’s Physics Graduate Program is the perfect environment for me to
optimize my way of thought because I would be surrounded with highly intellectual students and
faculty who share the same interests, not to mention the quality and prestige of the program
itself. Also, integration into the program would not be an issue because my experience in optics
research would go hand-in-hand with that of the precision-measurement research of Dr. Peter
Fritchel.
My research interests include astrophysics and cosmology but more specifically,
gravitation. Gravitation became a wonder to me after hearing about the General Theory of
Relativity (GTR) in my introductory mechanics course. The fact that gravity is the result of the
curvature of spacetime fabric was intriguing because it involved monstrous masses to do so, and
in theory, when incredibly dense objects form binaries, the curvature gets so distorted and
warped that ripples of spacetime or gravitational waves (GWs) form and translate throughout the
universe. The chaos of these events is what captivates me the most. Also, after taking an actual
course in GTR, I fell in love with the equations that described these kind of events because it was
like they were occurring on paper and one had to only imagine the underrated power of
gravitation.
In regards to gravity, there exists a worldwide effort to detect GWs; the Advanced Laser
Interferometer Gravitational-wave Observatory (aLIGO) is a complex Michaelson Interferometer
designed to detect these GWs by means of measuring differential length changes in its 4-km
arms. These length contractions are a response from GW’s nature of squeezing and compressing
matter it interacts with. LIGO’s sensitivity to these contractions is dependent on many factors
including that of the optimization of its optics. In addition, I have been working on
characterizing these optics for the past two years under the mentorship and supervision of Dr.
Joshua Smith at the Gravitational-Wave Physics and Astronomy Center (GWPAC) at Cal State
University Fullerton (CSUF). Together, with other members of the research group, conduct
experimental, GW physics. Specifically, we characterize a phenomenon called scattered light
from optics used for gravitational-wave detection. Moreover, scattered light in optics occurs
when photons (in this case from laser light) gather around and bulk up on the surface of mirrors.
On the other hand, scattered light decreases LIGO’s sensitivity to gravitational waves by adding
non-linear noise in the instrument readouts or by reducing its overall laser power.
In particular, our latest study involved a 40-kg, fused-silica mirror known as the input test
mass (ITM) sent from aLIGO. The ITM was found to have an abnormal antireflection (AR)
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coating on its secondary surface, with visible defects; thus, we used the Fullerton Imaging
Scatterometer to test whether this abnormal coating lead to an increase in scattered light for the
1064-nm, infrared light with which LIGO operates. In this apparatus, the test mass was
illuminated by a 1064-nm laser beam at near normal incidence, and the mass was then rotated in
one-degree increments, such that an image was obtained over a wide range of scattering angles.
These images were then processed through a custom MATLAB script to extract the Bidirectional
Reflectance Distribution Function (BRDF) for each angle. This BRDF is used to characterize
scattered light by essentially taking the ratio between the scattered and incident laser powers
(along with other factors). We found that the abnormal AR coating caused additional scattering
for 1064-nm light, visible in our images as cloudy patches that extended far from the central
beam spot. Although the scatter was higher than expected for a nominal AR coating, our
measurements allowed us to conclude that the AR coating had low enough total integrated scatter
for use in Advanced LIGO.
In transition, as part of MIT’s newest graduate physics student, I believe I would
integrate perfectly with Dr. Peter Fritchel’s research on precision measurement involving
gravitational-wave detectors. This is because I am already familiar with experimentation with
optics and the sensitive nature involved in its measurements. I am also aware that Dr. Fritchel
also works on Strong-Gravity and Gravitational Radiation studies. Since I have studied the
theory of General Relativity in my course work, I believe that I can also integrate well with his
research because I am well acquainted with the equations involved with strong-gravity sources
such as black holes and neutron stars. Better yet, the rigor of research along with coursework is
not something I am new to. I’ve stood my ground for the past three years by remaining in the
College of Natural Sciences and Mathematics (CNSM) Dean’s List.
In conclusion, my future plans consist of being a leading scientist at one of LIGO’s sites.
I would like to take on the role of optimizing and managing the optics. I realized that I wanted to
pursue this objective after I spent 2 months working at Virgo (Italy’s laser interferometer) as an
intern, as part of the University of Florida’s International Research Experience for
Undergraduates (IREU) program. There I saw first-hand how critical the science was. Everyone
was collaborating (sometimes through means of yelling) and working for a cause – to detect a
GW. There was passion involved and I wanted to be a part of that, especially since everyone
shared the same interests. On the other hand, I also would not mind going through a theoretical
approach on GW physics. Part of that is because I want to keep in close touch with the equations
that describe spacetime, while simulating events through computational/numerical work. At that
point, I would still contribute to the LIGO collaboration by providing simulated work to compare
to experimental findings.