Undergraduate Research Profiles

Below, you can read the profiles of a couple of University of Chicago physics majors who have been active in research.
     ► Clare Singer
     ► Yitian Sun

Clair Singer

Undergraduate Student: Class of 2018
Majors:  Physics and Mathematics
Hometown: Rockville, MD
Awards: UChicago Grainger Senior Scholarship, Goldwater Scholarship, Phi Beta Kappa, Astronaut Scholarship
Research: Atmospheric science, Condensed matter
Research Advisors: Elisabeth Moyer, Chris Arnusch and Roy Bernstein (BGU), Heinrich Jaeger

I joined Professor Heinrich Jaeger's lab during winter quarter of my 1st year. In the Jaeger lab, I worked with dry granular materials which are a class of matter that can exhibit the behavior of both liquids and solids. We worked to engineer the individual grain shape to produce desired macroscopic properties from the bulk material. The geometry of the grains can be chosen to increase geometric friction, or entanglement, between individual particles to transition the material from a flowing state to a rigid jammed state. We showed the ability to construct freestanding structures from unconfined grains. Stemming from this research work, we formed collaborations with scientists from MIT and ETH Zurich to create large-scale granular structures that were displayed in the 2015 Chicago Architecture Biennial. In the Jaeger lab, I also worked on a project in partnership with NIST to understand the ability of granular bundles to dissipate energy, with an end goal of designing the next generation of protective helmets to prevent concussions.

I participated in an international exchange during the summer after my 2nd year doing chemical engineering research in Israel. This Metcalf internship was sponsored by the IME. I worked with Dr. Chris Arnusch and Dr. Roy Bernstein at Ben-Gurion University of the Negev and spent three months living in Sde Boker, which is a tiny village in the middle of the desert. I was working on improving the efficiency of ultra-filtration membranes for removal of chemical and biological pollutants in drinking water supplies. I explored the possibilities of ink-jet printing assisted fabrication for modifying membrane surfaces. Initial results with infrared spectroscopy and atomic force microscopy demonstrated the validity of this method. With both Dr. Arnusch and Dr. Bernstein mentoring me, I was able to use a novel ink-jet printing technology in development in the Arnusch group and the polymer expertise of the Bernstein group to create more efficient water filtration membranes at a lower cost.

I came back to Chicago and transitioned into atmospheric science research. I joined Professor Liz Moyer's group in the Department of Geophysical Science during the fall quarter. We study the isotopic composition of atmospheric water vapor as a tracer for deep convection, cirrus formation, and troposphere-stratosphere exchange. I began by helping with mechanical and design tasks for the Chicago Water Isotope Spectrometer (ChiWIS) during winter quarter. Over the summer, I joined the Moyer group as a full-time researcher and went with the group to Nepal to participate in the StratoClim aircraft campaign. While there I experienced the joys and struggles of working on a 60-person team field campaign in a developing country. I helped with regular instrument maintenance and calibration as well as first looks at field data. During the last part of the summer, I took the lead on the reduction and analysis of the flight data collected during the campaign. I am currently working on comparisons between various water and particle measurements taken during the StratoClim campaign and combining these with balloon and satellite measurements. The scientific goals of the StratoClim campaign are to understand how important the Asian monsoon is as a source of water to the overworld stratosphere. I am continuing this research for my thesis project and am currently applying to Ph.D. programs to continue in atmospheric science.

Yitian Sun

Undergraduate Student: Class of 2018
Majors: Physics and Mathematics
Hometown: Beijing, China
Awards: Walter and Fay Selove Summer Research Stipend, Phi Beta Kappa, Dean's List
Research: Accelerator physics, HEP experiment, particle phenomenology, particle theory
Research Advisors: Kwang-Je Kim, Young-Kee Kim, Carlos E.M. Wagner

During my undergraduate years, I am fortunate to be involved in many research projects revolving around particle physics: from accelerator physics to high energy experiment, particle phenomenology and a little bit of particle theory. I started my first project in the summer of my first year with Prof. Kwang-Je Kim, aiming to find a way to increase the intensity and spectral quality of free electron lasers (FEL: lasers created by passing high energy electrons through alternating magnetic fields) by exploiting the coherence length of single pulses created by electrons. We started with a toy model of the self-amplified spontaneous emission (SASE) process but found out that coherence length comes in only as an indicator of coherence fall-off, and cannot be used to sustain the coherence. I worked out the amplitude's and bandwidth's dependence on the SASE phase shift, perturbations on electrons, and other factors. Afterwards, I studied the detailed dynamics of the SASE process and discovered that our model closely resembles the realistic process, so that we can make many inferences of the realistic case based on our model.

In the summer of my second year, I was involved in two high energy physics projects: an experimental project with Prof. Young-Kee Kim, and a phenomenology project with Prof. Carlos Wagner. Prof. Kim and I worked in collaboration with China on the R&D of CEPC, a future electron-positron collider. Fortunately, I got to work with the Chinese team in person during my stay in Beijing to kick off the project. My goal was to improve upon the event selection (i.e. cuts) of a sub-channel in the Higgs di-photon channel. Starting with first principles, I realized a flaw in a previous cut: it exploits the only difference of degrees of freedom between the major background and the signal, causing the sidebands to be destroyed in signal-fitting. I designed new cuts that carefully revolves around this degree of freedom to preserve the sideband, while also created a reconstruction algorithm specific to my channel’s event topology, allowing me to further improve on the Higgs measurement precision.

Meanwhile, I was working with Prof. Carlos Wagner, Dr. Peisi Huang, Daniel Spiegel and Roger Roglans on experimental constraints of a “blind spot” dark matter model living in the minimal supersymmetric extension of the standard model (MSSM). In the blind spot scenario, the matter-neutralino scattering cross sections are extremely low due to a cancellation between two diagrams involving the two CP-even Higgs, making the model still viable under the already stringent dark matter direct detection (DDMD) constraints. While this model sounds like an undetectable hideout, constraints on relic density from cosmology and on neutralino production from LHC detectors come in as well. We had fun exploring the parameter space by doing scans and making plots to determine how deep one has to go into the blind spot, and whether it has already been cleared out by the constraints. The fun is accentuated by the influx fresh data from the ICHEP 2016 conference happening just downtown Chicago that I was lucky to witness first hand by helping out Prof. Young-Kee Kim with the meeting. Our parameter space search concluded that the well-tempered neutralino will be fully constrained by future DDMD experiment, but the A-funnel neutralino still lives. The result was published in Phys. Rev. D.

After finishing this project in the winter of my third year, I wished to try out some more theoretical aspects of particle physics. Prof. Wagner came across an interesting proposal for a novel spacetime structure near the black hole horizon in an effort to explain the information paradox, and we started to investigate the reasoning behind it. During the summer, I caught up on recent developments about the black hole information paradox with Prof. Wagner, and we played around with derivations in the classical quantum fields in curved spacetime. As it turned out, the novel geometry is motivated by some novel dynamics involving back reaction. I am continuing to study the motivation behind this reasoning and its departure from a classical framework in my fourth year. Meanwhile, I am also restarting the Higgs analysis project with the CEPC group working towards a complete analysis of Higgs detection in the future collider.