Physics major Nicole Khusid, a rising senior at UConn, was featured in a UConn Today article about her research. Nicole has been working on gravitional lensing of distant sources of gravitational waves, seeking to understand their multimessenger signals and detectability by future astrophysics facilities. Nicole was awarded a SURF (Summer Undergraduate Research Fund) award to perform this research wtih Prof. Chiara Mingarelli. For the full story, see the article in UConn Today.
The following article appeared in UConn Today on May 20, 2021 under by-line
Physicists are one step closer to describing an anomaly, called the Muon g-2, that could challenge the fundamental laws of physics. It seems the muon may be breaking what have been understood as the laws of physics, and the findings announced on April 7th were met with much excitement and speculation at what this might mean. UConn physics researchers Professor Thomas Blum and Assistant Professor Luchang Jin helped pioneer the theoretical physics behind the findings, and they recently met with UConn Today to help explain the excitement.
What is a muon, and how do you study them?
Blum: A muon is a “fundamental particle,” meaning it’s an elementary particle like an electron or a photon. Muons are unstable, so they don’t live very long. Unlike an electron, where we can focus on them as long as we want and do measurements, we only have a little bit of time to take measurements of muons.
The way researchers perform the experiment is by slamming particles into other particles to create the muons, and they eventually collect them into a beam. This beam of muons travels at almost the speed of light where they live a little bit longer than they would if they were at rest. That’s Einstein’s theory of relativity in action.
The researchers put the muons into what’s called a storage ring where, eventually, they decay into other particles, and it’s those other particles that are detected in the experiment.
Muons have a property called a magnetic moment, which is like a little compass that points in the direction of the magnetic field that it’s in. In the storage ring, there’s a uniform magnetic field, and as the muons are going around in the storage ring, their magnetic moment, which would be perfectly aligned with their direction of travel if there were no anomaly, actually precesses with respect to the direction of travel as it goes around the ring, because of the interaction with the magnetic field.
It’s that precession that they’re measuring, because the precession is proportional to the strength of the magnetic moment. We can measure this magnetic moment extremely precisely in experiments, and we can calculate its value theoretically very precisely, to less than one-half part per million. Then we can compare the two and see how well they agree.
Can you explain the excitement surrounding these results?
Blum: For a long time — almost 20 years — the best measurement had been done at Brookhaven National Lab on Long Island, where they measured this magnetic moment very precisely, and found that it didn’t agree with our best fundamental theory, which is called the Standard Model of particle physics. The discrepancy wasn’t big enough to say that there was definitely something wrong with the Standard Model or not.
The new results are from a new experiment done to measure the magnetic moment even more precisely. That effort has been going on at Fermilab outside of Chicago for a few years now, and they just announced these results in early April. Their measurement is completely compatible with the Brookhaven value, and if you take the two together, then the disagreement with the Standard Model gets even worse: it now stands at 4.2 standard deviations.
People are very excited, because this could possibly signal that there is new physics in the universe that that we don’t know about yet. The new physics could be new particles that we’ve never seen before, or new interactions beyond the ones we know about already and that could explain the difference between what’s measured and what’s calculated. So that’s what everybody’s excited about.
Can you tell us about the Standard Model?
Jin: The Standard Model describes electromagnetic interactions between charged particles. It also describes the so called weak interactions, which is responsible for nuclear decay. The weak interactions become more important in high energy collisions, and unifies with the electromagnetic interactions. Lastly, the Standard Model describes the strong interactions, which bind quarks into nucleons and nuclei.
Basically, the Standard Model describes everything around us, ranging from things happening in our daily lives to the high-energy proton collisions in the Large Hadron Collider, with the major exception being gravity, which is only sort of visible, but we can feel it because gravity forces always add up, and there are a lot of other massive objects around us. It also doesn’t include dark matter, if we actually do have that in the universe.
People believe, and I think this is really true, that the Standard Model cannot possibly describe everything to extremely high precision, especially when we accelerate subatomic particles to very high energies. However, it was not very clear how high the energy or the precision has to be before we can see some discrepancies. We know the upper bound — usually referred to as the Planck scale, where the Standard Model has to fail due to the omission of gravity. But the Planck scale is so high that there is little hope to be able to perform experiments at that high energy. It is very nice to find a concrete example that the Standard Model actually misses something, and the g-2 anomaly is a very good candidate.
What roles did you each have in this research?
Jin: Theoretically, we decomposed the g-2 into contributions from the different types of interactions. At present, most of the values are obtained by analytic calculations of the various contributions. Other experimentally measurable quantities that have little to do with the muon magnetic moment experiments in terms of what they measure can be related through the Standard Model to the Muon g-2 value. So, to a large extent, this can still be viewed as a theory prediction. Blum pioneered the first lattice calculation for a certain g-2 contribution called the hadronic vacuum polarization, which doesn’t use experimental data at all.
Blum: Jin came up with new methods to compute the Hadronic Light-by-Light contribution which allowed us – with colleagues at Brookhaven National Lab, Columbia University, and Nagoya University – to compute it completely for the first time without experimental input. What Jin and I are doing, along with a host of other theorists around the world, is trying to better calculate the value of this magnetic moment from the theory side, so that we can have an even better comparison with the experimental measurements.
Jin: The Standard Model itself has a few parameters, which for most, we know very, very precisely. This includes the masses of the fundamental particles. In principle, as one might imagine, the theory prediction of the Muon g-2 is a very complicated expression just in terms of these numbers. We are not able to do that yet, but maybe soon we can. We expect that if we continue to improve our calculations, and as computers continue to get faster, the last digit determination may become more accurate.
To dig deeper into the science behind the findings, read Blum and Jin’s feature article on the findings in CERN Courier.
Professor Cara Bettersby’s research is featured in the article “The Study of Big Data: How CLAS Researchers Use Data Science” published by UConn Today.
Prof. Battersby’s work focuses on describing and studying the center of the Milky Way galaxy, which she calls an “experimental playground” for the distant cosmos. Her work described the spectroscopy of the galaxy’s center, which analyzes imagery to understand the chemical makeup of the area, as well as its temperature and the velocity of objects.
Battersby works on data from the Submillimeter Array facility, a collection of eight powerful telescopes situated atop Mount Maunakea in Hawaii. The telescope can collect up to a terabyte of data every day, and Battersby’s project used 61 days of data.
Battersby refers to her computer as “her laboratory,” and ensures the students in her classes do, too. In her courses, she often assigns programming and analysis problems, like using a large data set to determine the material composition of the Sun.
“We have a lot of the tools to train students in data science,” she says. “Research is moving in that direction, and students in our programs are prepared for it.”
New Physics PhD graduate Yasaman Homayouni is featured in a story on the class of 2021 from the College of Liberal Arts and Sciences (CLAS). For the full story of what inspired Yasaman and other students during their time at UConn, see the article in UConn Today.
Professor of Physics Nora Berrah has been awarded the International Blaise Pascal Chaire d’Excellence, a prestigious honor whose previous winners include scientists and scholars from a wide range of disciplines, including multiple Nobel laureates. Her award was selected by a committee of scientists and voted on by the Permanent Commission Regional Council of the Région Île-de-France.
This award is bestowed to scientists of international reputation who are invited to conduct research in the Paris area. The goal is to establish international collaborations and exchange, as well as share science globally. In Berrah’s case, the collaboration is between UConn and the Commissariat à l’énergie atomique et aux énergies alternatives de Saclay (CEA, Paris Saclay). The collaborative work is aimed to push the frontiers of science, as well as enrich and facilitate international research.
The Région Île-de-France selects every year four laureates of high international standing in their field of expertise. All research areas are included, such as the humanities, arts, and sciences, in the selection of the awardees. Six Nobel laureates have been selected for the award since 1996. Prof. Berrah was selected by the Blaise Pascal Chaire Committee for the field of Fundamental Physics.
For more information about Professor Berrah’ award, see the article in UConn Today
I would like to share some thoughts on Munir Islam who recently passed away. Prof. Islam came to UConn in 1967 from a faculty position at Brown University. In the late 1970s there were two particle theorists at UConn, Profs. Kurt Haller and Munir Islam. They set about building an elementary-particle theory program here and garnered the support of then Physics Head Joe Budnick and CLAS Dean Julius Elias. They soon obtained funding for a new Department of Energy initiative to support particle theory in the Department. In 1979 they
were able to bring me in as an Associate Professor and Mark Swanson as an Assistant Professor. So eager were Kurt and Munir to bring us in, they chose to forego the summer salary that they had been awarded on the DOE grant. The impact of the DOE grant on the UConn administration was quite far reaching and led to further internal support. Within a few years I had been tenured and promoted to Full and Mark had been tenured and appointed to Associate at our Stamford branch, where he later became an administrator.
After that, Kurt and Munir were able to secure a bridge position with the DOE that would provide five years of support, provided the UConn administration would create a tenure track position for the recipient. This they agreed to do, and so we brought in Daniel Caldi at the Assistant level, who subsequently was appointed Associate with tenure. Dan eventually opted to leave us for SUNY Buffalo, but our particle group was then able to convince the UConn administration to let us keep the position, and we then hired Gerald Dunne. Gerald went up the ladder very quickly to tenured Full professor. The success of our program enabled us subsequently to bring in Alex
Kovner, followed by Tom Blum (both now tenured Full) and current Assistant Luchang Jin. The success and endurance of the particle group for more than forty years now is a testament to the foresight and the unwavering and unabating commitment of Kurt and Munir to it, and it serves as permanent memorial to both of them.
Munir Islam always retained an enthusiasm for research, an enthusiasm which did not diminish at all after he retired. He focused on fundamental problems in particle physics, with particular emphasis on the theory of the structure of the proton as revealed by high-energy proton-proton scattering. This is perhaps best evidenced in what essentially became a lifelong collaboration with his former graduate student Richard Luddy (at the right, with Prof Islam at the left in the above photograph) as the two of them grappled with Munir’s deep ideas on proton scattering during many of Munir’s later years as a Professor and then as an Emeritus. Munir had a gift for simple pictorial explanations of his research, which he was able to explain lucidly in a lecture for visiting high-school teachers and students during an open house. Munir was urbane, worldly, and wise, and it was a great joy to have him not just as a colleague but also as a friend. He will be sorely missed by all of those that knew him and especially by me as my career owes so much to him. In appreciation, Philip Mannheim.In appreciation,
Dr. David Katzenstein, a friend, and benefactor of the UConn Department of Physics, passed away on January 25, 2021 due to Covid-19. David was the son of Henry Katzenstein, the first Physics Ph.D. from UConn and a major benefactor of our Department. Currently, both the annual Katzenstein Distinguished Lecture and the Katzenstein Prize for a senior, undergraduate paper were endowed by the Katzenstein family.
David himself was an Emeritus Professor of Medicine at the Stanford University Medical School, specializing in Infectious Diseases and Geographic Medicine. He focused on the treatment and prevention of HIV-AIDS, particularly in sub-Saharan Africa. He died in Harare, Zimbabwe where he had moved in 2016 to continue his important work after his retirement from Stanford.
Looking for ripples in the fabric of spacetime.
UConn astrophysicist Chiara Mingarelli is part of a team of researchers who recently published data on a hint of a signal that sent ripples of excitement through the physics community. These monumental findings are the culmination of twelve and a half years of data gathered from NANOGrav — a network of pulsars across the galaxy — all in the hopes of detecting gravitational waves.
Gravitational waves are generated when galaxies merge and supermassive black holes at their centers collide and send low-frequency gravitational waves out into the universe. The team thinks the source of the signal could be gravitational waves, but it will take about 2 more years of data to be sure.
The findings sparked the interest of other physicists with their own speculations about the signal, such as cosmic strings or primordial black holes. Though still a couple of years away, Mingarelli says the final results could also help test General Relativity or even open the door to entirely new physics.
This article first appeared on UConn Today, February 15, 2021
UConn Physics alumnus Dr. Michael Wininger (BS, 2003) was recently featured in the professional journal O&P Almanac (Orthotics and Prosthetics). The article describes how his eclectic background, beginning with degrees from UConn, has enabled him to lead innovations in several areas of health research. Mike is currently an Assistant Clinical Professor in the Biostatistics Department at the Yale School of Public Health while also holding a co-appointment with the Department of Veterans Affairs Cooperative Studies Program. Michael says that former Professor Ed Pollack was particularly instrumental in mentoring towards a successful career, and in gratitude has been a frequent contributor to the Edward Pollack Endowment Fund, which supports our annual Pollack Lecture in Atomic Physics. Some of the old-timers around the department remember Mike for his always energetic presence around the department and help with our bicycles.
The Sloan Digital Sky Survey’s fifth generation – a groundbreaking project to bolster our understanding of the formation and evolution of galaxies, including the Milky Way – collected its very first observations on the evening of October 23.
Image: The Sloan Digital Sky Survey’s fifth generation made its first observations earlier this month. This image shows a sampling of data from those first SDSS-V data. The central sky image is a single field of SDSS-V observations. The purple circle indicates the telescope’s field-of-view on the sky, with the full Moon shown as a size comparison. SDSS-V simultaneously observes 500 targets at a time within a circle of this size. The left panel shows the optical-light spectrum of a quasar–a supermassive black hole at the center of a distant galaxy, which is surrounded by a disk of hot, glowing gas. The purple blob is an SDSS image of the light from this disk, which in this dataset spans about 1 arcsecond on the sky, or the width of a human hair as seen from about 21 meters (63 feet) away. The right panel shows the image and spectrum of a white dwarf — the left-behind core of a low-mass star (like the Sun) after the end of its life.Image Credit: Hector Ibarra Medel, Jon Trump, Yue Shen, Gail Zasowski, and the SDSS-V Collaboration. Central background image: unWISE / NASA/JPL-Caltech / D.Lang (Perimeter Institute).
“In a year when humanity has been challenged across the globe, I am so proud of the worldwide SDSS team for demonstrating — every day — the very best of human creativity, ingenuity, improvisation, and resilience. It has been a wild ride, but I’m happy to say that the pandemic may have slowed us, but it has not stopped us,” says Juna Kollmeier, director of the project known as SDSS-V.
The project is funded primarily by an international consortium of member institutions, along with grants from the Alfred P. Sloan Foundation, U.S. National Science Foundation, and the Heising-Simons Foundation.
Jonathan Trump, UConn assistant professor of physics, has a long history with SDSS, and is one of the architects for the fifth installment of the program. He is also serving as the cadence coordinator for the project’s black hole science goals.
“My very first undergrad research project was an SDSS project. I have worked on SDSS as a post-doc, and I am working on it now as faculty,” Trump says. “I’ve been part of it from the first SDSS iteration, and as it has taken off, so has my career.”
Trump and his colleagues will focus on three primary areas of investigation with SDSS-V, each exploring different aspects of the cosmos using different spectroscopic tools. Together, these three project pillars—called “Mappers”—will observe more than six million objects in the sky, and monitor changes in more than a million of those objects over time.
The survey’s Local Volume Mapper will enhance our understanding of galaxy formation and evolution by probing the interactions between the stars that make up galaxies and the interstellar gas and dust that is dispersed between them. The Milky Way Mapper will reveal the physics of stars in our Milky Way, the diverse architectures of its star and planetary systems, and the chemical enrichment of our galaxy since the early universe. The Black Hole Mapper will measure masses and growth over cosmic time of the supermassive black holes that reside in the hearts of galaxies, as well as the smaller black holes left behind when stars die.
Trump says another novel aspect of SDSS-V is repeat observation, which he will be scheduling over the duration of the project as cadence coordinator, to help gather more data about the evolution of different features of matter near black holes.
“SDSS-V has more repeat observations as part of the plan. I would say that broadly in astronomy there is an emphasis on repeat observations,” he says. “For instance, black holes are fascinating – they are rips in space-time, and they are extremely exotic. Even one snapshot reveals how exotic they are, but they are also dramatically variable, and when we observe them day-to-day, week-to-week, year-to-year, we see dramatic changes in their emission, which we think correspond to dramatic changes just beyond the event horizon of the black hole. We are learning that you can reveal a lot about the physics of what is going on around black holes by watching them as a function of time.”
SDSS-V will operate out of both Apache Point Observatory in New Mexico, home of the survey’s original 2.5-meter telescope, and Carnegie’s Las Campanas Observatory in Chile, where it uses the 2.5-meter du Pont telescope. SDSS-V’s first observations were gathered in New Mexico with existing SDSS instruments, as a necessary change of plans due to the pandemic. As laboratories and workshops around the world navigate safe reopening, SDSS-V’s own suite of new innovative hardware is on the horizon—in particular, systems of automated robots to aim the fiber optic cables used to collect the light from the night sky. These will be installed at both observatories over the next year. New spectrographs and telescopes are also being constructed to enable the Local Volume Mapper observations.
Trump points out that another important aspect of SDSS, especially in a time of remote learning and researching, is the fact that data are made public and accessible.
“It is easy to access and mine the SDSS databases and make interesting studies,” he says. “They have wonderful tutorials for schools and for researchers to get started. They make it so easy for people to dive in. It is a very rich opportunity; it’s well organized and publicly shared.”
To learn more about the program, explore the data, or keep up with the research, visit https://www.sdss5.org/
This article first appeared online on UConn Today, November 2, 2020.