Carnegie Mellon University

Department of Physics

Mellon College of Science

News Snippets from CMU Physics

Fall/Winter 2017–18

Cloud chamber shows radiation traces

September 2017 – Undergrad Nuclear Physics

CMU physics professor Reinhard Schumacher highlights a dry-ice-free cloud chamber for visualizing ionizing radiation in an educational YouTube video. The work was performed with undergraduate Adrian Relic as a research project. The video shows how they constructed their chamber and how it responds to α, β and γ radiation. Along the way, the video presents the nature of these radiation types and the sources used to produce them. It also features a particularly nice example of an α particle undergoing Rutherford scattering in the chamber gas (picture; scale is in centimeters).

New graduate program requirements

September 2017 – New graduate program requirements in effect

New graduate program requirements are in place for incoming graduate students and current pre-candidate graduate students were able to choose to qualify for PhD candidacy under the old or new set of requirements. An UPDATED GRADUATE HANDBOOK provides details.

With this step, the department aims to provide students with more time for and greater flexibility in research and focuses their evaluation for candidacy more on research promise. A reduction in core courses will enable students to engage in more serious research projects during the first year of graduate studies and facilitates rotation between research groups. Other aspects of the program, such as academic performance, breadth courses, and teaching requirements, remain unchanged. These modifications bring our program requirements better in line with its desired goals and will enhance the learning experience of our graduate students. Read more HERE

Spring/Summer 2017

COHERENT neutron experiment

August 2017 – Diana Parno's involvement in COHERENT

The COHERENT experiment at the Oak Ridge National Laboratory’s Spallation Neutron Source (SNS, shown left) has recently detected and measured the coherent elastic scattering of neutrinos off of nuclei – a process that is predicted by the Standard Model of physics, but has never been observed before. The new findings, published in the journal Science, uncover a fingerprint of neutrino-nucleus reactions that will provide better understanding of neutrinos, the dynamics of neutron star formation and supernovae explosions. It could also provide parameter limits for future experimental dark matter searches.

More than 80 researchers from 19 institutions contributed to this study. Diana Parno, an assistant research professor in the Department of Physics, is a member of the COHERENT collaboration and contributed simulations that calculate the number of neutrinos that pass through the SNS detectors. She plans to continue working on the project while at Carnegie Mellon. Read more on this research at the AAAS website.

Eclipse News

August 2017 – The Solar Eclipse at Carnegie Mellon's Pittsburgh campus

On August 21, 2017, Sun and the moon aligned, causing a great lack of UV ray exposure in some parts of North America. In celebration of this joyous occasion, the Carnegie Mellon Astronomy Club held a viewing event on campus, where solar eclipse glasses were given out like candy. In addition, telescopes with the proper eye damage prevention equipment were set up  to get a closer look at the movement of these celestial bodies. This gathering of astronomical enormity took place from 12:00 noon till 4:30 PM. Over 4,000 people were in attendance. At about 1:11 PM, eclipsing started and around 2:30 PM, the peak of the eclipse was observed in Pittsburgh, PA. While totality was not observable in the immediate area, a partial eclipse of about 80% cover baffled the observers. In the dim lighting of the partially visible hot ball of plasma, the student body and the relevant community members of Carnegie Mellon all gathered together and experienced the wonders and marvels that the laws of physics have to offer. It was truly a memorable event, not only for new students at orientation, but for all people involved! For those who missed it: See you all on April 8, 2024!

(Eyewitness report by Joanne Hsueh)

Xin Wang

May 2017 – Xin Wang earns Ph.D. with thesis on “Elasticity of lipid membrane leaflets"

The biological functions of lipid membranes often depend on fascinating elastic properties which in turn arise from molecular structure: membranes assemble spontaneously from lipid molecules, forming a 5 nm thin fluid film that consists of two individual molecular sheets. This film is hard to stretch but bends easily to adjust its local curvature. And upon imposing curvature, each individual lipid leaflet bends around an internal surface called the “pivotal plane”.

Working with Prof. Deserno, Xin Wang developed precise methods for pinpointing the pivotal plane and in the process discovered a novel method for measuring the so-called "lipid tilt modulus"—a parameter that determines how easily the orientation of individual lipids an deviate from the direction perpendicular to the membrane’s surface. This modulus matters whenever local membrane phenomena are studied, such as membrane pores or inserted proteins. Xin’s work therefore contributes to the ongoing quest to better understand the molecular origin of the fundamental mechanical structures that protect our cells from the environment.

Stephanie O'Neil

May 2017 – Stephanie O’Neil receives the Physics Department’s RE Cutkosky Award and the JP Fugassi and LE Monteverde Award from MCS

With a double major in physics and creative writing, Stephanie O’Neil is now leaving CMU where she has been a dedicated student and researcher, as well as an active member of the campus community. With the Dr. J Paul Fugassi and Linda E Monteverde Award, MCS recognizes the graduating female senior with the greatest academic achievement and professional promise. The Richard E Cutkosky Award is presented each year to an outstanding graduating senior in the physics department.

Beyond her flawless academic record, Stephanie was a whirlwind of activities as a member of the Kiltie Band, the Flute Choir, the All University Orchestra, as well as the Physics Steering Committee, the secretary of the Astronomy Club and a tutor in the Physics Upper Class Course Center. Last year, she was the undergraduate representative for the MCS college council. In undergraduate research, she has been studying dwarf galaxies with Assistant Professor of Physics Matthew Walker. In this work, she focused on inferring dark matter contents of dwarf spheroidal galaxies that orbit our milky way. Stephanie was also greatly appraised by her faculty mentors as REU (Research Experience for Undergrad program of the NSF) scholar at William & Mary and at MIT in the summers of 2015 and 2016. After graduation, she will join MIT’s Kavli Institute for Astrophysics and Space Research to pursue a Ph.D. in astrophysics.

Freeman PhD thesis defense

May 2017 – Krista Freeman earns Ph.D. with thesis on “Viral DNA Retention and Ejection controlled by Capsid Stability

Viruses are submicroscopic pathogens that infect every branch, twig and sprig of the tree of life. They consist of little more than a genome stored inside a protein shell, called the capsid, and exploit the cellular machinery of the organisms they infect for their own replication. Many bacterial viruses, and also some human ones, store their genome under enormous pressure in the capsid—more than 10 times that of an inflated car tire. Because such genomes consist of DNA that is several hundred times longer than the size of the capsid, the highly charged DNA strand must be very tightly squeezed to fit in. Upon infection, the capsid opens up and the DNA gets ejected into the host cell much like a jack-in-the-box.

In her thesis, Krista investigated the time course of this dynamic process and the physical principles underlying the construction of capsids that can withstand such enormous pressures. Besides gaining fascinating insights into these genome-loaded nano-machines, such studies also touch upon basic medical concerns: understanding the physical mechanisms that viruses rely on may open new avenues to combat them. And since this invokes general physical principles, the virus may not easily be able to respond with adaptive mutations.

Satpathy Hugh Grant teaching award

May 2017 – Sidd Satpathy receives Hugh Young Teaching Award

As a teaching assistant (TA), Siddharth Satpathy, a Ph.D. candidate in the Department of Physics, is described as conscientious, compassionate, dedicated, nurturing, and helpful – in short, “one of the best TA’s ever” by students and faculty alike. During the last three years, Satpathy – better known as Sidd – has taught five different sections of the introductory course Physics for Science Students and Calculus in Three Dimensions, the latter for the Department of Mathematical Sciences. Sidd also served for two years as an instructor in Carnegie Mellon University’s Summer Academy for Math and Science for high school students.

In recognition of his enthusiasm for teaching and his unyielding dedication to going above and beyond for his mentee students, Siddharth Satpathy has been awarded the 2017 Hugh Young Graduate Student Teaching Award. Congratulations, Sidd!

Belle II detector roll-in

April 2017 – Belle II Project at KEK in Tsukuba/Japan

The Belle experiments study collisions of electrons and positrons at a total energy of ~10 GeV. This energy is chosen to produce B mesons: particles composed of a heavy "bottom" quark and a light anti-quark. These are of special interest since they violate "CP symmetry", that is, they differ in the behavior of matter and anti-matter. This asymmetry poses one of the deepest mysteries of particle physics, and solving it may shed light on the unexplained observation that the Universe is dominantly made of matter, rather than anti-matter. Belle II is an improved version of the very successful first Belle experiment and aims to collect a larger data samples with an improved detector.

CMU is involved in a variety of activities at Belle II: Prof. Roy Briere is co-chair of the charm physics analysis group, exploring the physics reach and planning analyses on these topics. Postdoc Jake Bennett is data production coordinator, overseeing production and processing of simulated Monte-Carlo samples and preparing for real data-taking in the near future. Together, Jake and Roy are also responsible for calibrating dE/dx measurements from the CDC wire chamber, one of several methods employed to distinguish the identities of the various particles measured in the Belle II detector.