Each year the Department of Physics recognizes the outstanding research and dissertation of a PhD graduate. Nirupama Sensharma is one of the recipients this year.
Sensharma’s thesis is titled “Wobbling Motion in Nuclei: Transverse, Longitudinal and and Chiral.” She was advised by Professor Umesh Garg. Eariler this spring Sensharma received the 2021 Cornelius P. Browne Memorial Award in Nuclear Physics for her work on wobbling motion in gold nuclei and outstanding outreach effort through her project Nuclear Energy – The Better Energy. Sensharma is heading to a postdoc position at the University of North Carolina under the mentorship of another ND PhD alumni, Daniel Ayangeakaa.
This award is given for demonstrated character and leadership, and for service to the University, the Department of Physics, and to his or her fellow physics majors. Paul Chagnon was a Professor in the department who retired in 1995, whose many contributions we honor with this award.
The College of Science at the University of Notre Dame is pleased to announce that Umesh Garg, a professor in the Department of Physics, has receiveda Fulbright U.S. Scholar Program award to India from the U.S. Department of State and the J. William Fulbright Foreign Scholarship Board.
Garg will carry out research and deliver lectures at the University Grants Commission-DAE-Consortium for Science Research, Kolkata, as part of a project to investigate novel quantal rotations in nuclei. This work will focus on studies of wobbling motion in triaxial nuclei (the shape of a three-dimensional oval with three unequal axes) and on exploration of the chiral parity violation phenomenon.
As a Fulbright Scholar, Garg will share knowledge and foster meaningful connections across communities in the United States and India. Fulbright recipients engage in cutting-edge research and expand their professional networks, often continuing research collaborations started abroad and laying the groundwork for forging future partnerships between institutions. Upon returning to their home countries, institutions, labs, and classrooms, they share their stories and often become active supporters of international exchange, inviting foreign scholars to campus and encouraging colleagues and students to go abroad. As Fulbright Scholar alumni, their careers are enriched by joining a network of thousands of esteemed scholars, many of whom are leaders in their fields. Fulbright alumni include 60 Nobel Prize laureates, 86 Pulitzer Prize recipients, and 37 who have served as a head of state or government.
This is Garg’s second Fulbright award. He was previously named a Fulbright Specialist in 2015. Garg joined the University of Notre Dame in 1982 as an assistant professor in the Department of Physics, and was appointed full professor in 1994. He earned his bachelor and master of science degrees from Birla Institute of Technology and Science, Pilani, India, and his doctorate in physics from the State University of New York at Stony Brook. He has been a Fellow of the American Physical Society since 1999. He has also received a Kaneb Award for Excellence in teaching, the Notre Dame Faculty Award in 2018, was named the recipient of the inaugural Terrence Akai Award for service to international students, and in 2017 was named an AAAS Fellow.
The Fulbright Program is the flagship international educational exchange program sponsored by the U.S. government and is designed to forge lasting connections between the people of the United States and the people of other countries, counter misunderstandings, and help people and nations work together toward common goals. Since its establishment in 1946, the Fulbright Program has enabled more than 390,000 dedicated and accomplished students, scholars, artists, teachers, and professionals of all backgrounds to study, teach and conduct research, exchange ideas, and find solutions to shared international concerns. The Fulbright Program is funded through an annual appropriation made by the U.S. Congress to the U.S. Department of State. Participating governments and host institutions, corporations, and foundations around the world also provide direct and indirect support to the program, which operates in more than 160 countries worldwide.
Nirupama Sensharma received the 2021 Cornelius P. Browne Memorial Award in Nuclear Physics for her work on wobbling motion in gold nuclei and outstanding outreach effort through her project Nuclear Energy – The Better Energy.
Cornelius P. Browne served as the director for the Nuclear Structure Lab for nearly thirty years. Through his hard work and dedication he steered the lab through the most successful period in its history. In honor of Dr. Browne this award is presented annually to an outstanding Nuclear Physics graduate student who has exemplified Professor Browne’s work ethic.
Originally published by Janet Weikel at isnap.nd.edu on March 15, 2021. View here.
Professor Umesh Garg has been appointed an Editor of Progress of Theoretical and Experimental Physics (PTEP), an international, fully open access, online-only journal published by the Physical Society of Japan.
PTEP is the successor to Progress of Theoretical Physics (PTP), which was founded in 1946 by Hideki Yukawa, the first Japanese Nobel Laureate. PTEP has a broader scope than that of PTP covering both theoretical and experimental physics.
A monthly publication, PTEP mainly covers areas including particles and fields, nuclear physics, astrophysics and cosmology, beam physics and instrumentation, and general and mathematical physics. Garg’s primary area of responsibility will be nuclear physics.
Scientists catch their first glimpse of an intricate type of nuclear movement.
For the first time, physicists have clearly observed a rare and complex motion of atomic nuclei called longitudinal wobbling.
An atomic nucleus is composed of protons and neutrons, collectively called nucleons. In an excited state, some nuclei with an odd number of nucleons exhibit a complex wobble — like that of a spinning top — because of their imbalanced geometry. Previous observations detected wobbling around only either the longest or shortest axis of nuclei having fewer than 170 nucleons.
Nirupama Sensharma at the University of Notre Dame in Indiana and her colleagues bombarded a ytterbium target with fluorine ions to produce the form, or isotope, of gold called gold-187. Analysis of gamma rays that the nuclei produced as they decayed indicated that the nuclei were wobbling. This makes 187Au the heaviest known wobbling isotope.
The team detected the 187Au nucleus wobbling about an axis that was neither its longest nor its shortest, but was of an intermediate length — the first clear observation of such behaviour.
Click here to see the original highlight on Nature.
The article below was published on February 5, 2020 on APS Physics website, written by Marric Stephens, a freelance journalist.
Synopsis: Gold Nucleus is Wobbly
A rare kind of nuclear spinning motion has been detected in an isotope of gold.
Planets, footballs, and even some large molecules have something in common: they rotate as rigid, classical bodies. Atomic nuclei are another matter, in that quantum mechanics allows strange new modes of motion. In experiments involving a short-lived isotope of gold, 187Au, Nirupama Sensharma at the University of Notre Dame, Indiana, and colleagues have observed an unusual rotational mode, predicted in 2014, called longitudinal wobbling. Seeing this wobbling mode in such a heavy nucleus puts constraints on theories of nuclear structure.
Like other nuclei with an odd number of nucleons, 187Au can be modeled as a spinning ellipsoid with an independent nucleon orbiting within it. In its ground state, the system rotates smoothly about one of the ellipsoid’s axes. But at higher energies, 187Au, like other ellipsoidal nuclei with three unequal axes, can exhibit a more complex motion. This motion comes from the nucleon tugging on the nucleus, making its rotation axis wobble like an unbalanced spinning top. Alignment between the nucleon’s orbital axis and the nucleus’s long or short dimensions produces transverse wobbling, which has been seen in a handful of nuclei. Sensharma and colleagues’ study provides the first clear detection of longitudinal wobbling, in which the nucleon’s orbital axis aligns with the nucleus’s intermediate-length axis.
The researchers spotted the new mode’s signature in the nuclear debris created by firing fluorine ions at an ytterbium target. Among the isotopes produced in the collision were a host of 187Au nuclei in various excited states. By analyzing the gamma rays emitted as these excited states decayed, the team reconstructed the initial population—including the predicted longitudinal wobbling states. They expect further examples of heavy triaxial nuclei to show up in future studies.
Nuclei can be round, like a soccer ball, or oblong, like a football. Others are slightly oblong but misshapen, like a potato. One of the only two ways to observe the third shape, rarely encountered, is when the nucleus wobbles like a lopsided top.
Researchers had previously seen these rare triaxial nuclei wobble on their shorter, transverse axes. But University of Notre Dame researchers and collaborators recently discovered that the nuclei also wobble on their intermediate axes. Their research, “Longitudinal Wobbling Motion in 187Au,” was published recently in the premier physics journal, Physical Review Letters.
The work took four to five days to complete once the team assembled at Argonne National Laboratory, in Illinois. Notre Dame physics graduate student, Nirupama Sensharma, who was the first author on the paper, spent about a year analyzing the data. Her work was highlighted recently in Nature.
Sensharma worked with Umesh Garg, professor in the Department of Physics, to develope an experiment using an isotope of gold to find out if the nucleus wobbled as predicted in a theoretical model developed by Stefan Frauendorf, also a professor in the Department of Physics. Frauendorf had hypothesized that triaxial nuclei would have two different types of wobbling motion.
The fundamental research, which Garg said does not have an immediate application for technology, was chosen as an editor’s selection in the journal. It was also highlighted as a synopsis in Physics, the online magazine of the American Physical Society. Papers selected for coverage must include an experimental breakthrough, or provide a theory with a new perspective, among other criteria.
“Where its importance lies is in confirming the predictive power of the underlying theoretical framework, generating more confidence in other predictions about nuclear physics,” Garg said. “This, among other things, can help us understand how various processes happen in stellar environments, and how heavy elements, like gold, are formed in the universe.”
In 2016 Frauendorf suggested an experiment on a gold nucleus after predicting the wobbling should exist.
“Professor Garg’s group created an outstanding experiment to measure the distribution of radiation,” Frauendorf said, noting that the experiment validated his prediction.
The work, funded by the U.S. Department of Energy, was completed at the Argonne National Laboratory inside an instrument called Gammasphere. Gammasphere is the world’s most powerful gamma ray spectrometer, and collects gamma ray data following the fusion of heavy ions. Inside Gammasphere, a beam of ions and the target nucleus combine to create a much heavier, highly excited nucleus that gives off gamma rays. By observing the pattern and properties of the gamma rays, researchers can discover the structure of the nucleus – and a wobbling nucleus has a very specific structure.
Initially, Garg and his collaborators planned to look for wobbling in 189Au, but ended up accidentally populating another isotope of gold, 187Au, more strongly. The mistake was a serendipitous one.
“That one was right, it turns out,” Garg said. “But that’s how science goes; if we had done the experiment exactly as planned, I probably would have come back and said, this doesn’t very much seem like what we’re looking for.”
In addition to researchers from Notre Dame and Argonne National Laboratory, in Lemont, Illinois, other collaborators include scientists from Technische Universitat Munchen, Garching, Germany; the United States Naval Academy, University of North Carolina Chapel Hill, Duke University, University of Maryland, the Consortium for Scientific Research, Kolkata, India, and the Tata Institute of Fundamental Research, Mumbai, India.
Professor. Umesh Garg has been appointed as a Guest Professor at Xi’an Jiaotong University in China. The certificate of appointment was presented to Prof. Garg at a special ceremony at XJTU in July 2019.
Xi’an Jiaotong University is one of the national TOP-9 universities under the direct jurisdiction of the State Education Ministry of China. The university was founded in Shanghai in 1896. In 1956, main part of the university was moved to Xi’an, and renamed Xi’an Jiaotong University (XJTU). As one of the first batch universities in China, XJTU was supported by the central government in the seventh and eighth five-year plans, as well as China’s “Project 211” and “Project 985” to develop into a world-class university. Now, XJTU is on the List of World-class Universities and First-class Disciplines released in 2017 by the Ministry of Education of China.
The Guest Professor is one of the highest honors at Xi’an Jiaotong University and is bestowed by the President of XJTU on academics of very high international repute who have significant connections with the University. “Prof. Garg highly deserves to receive this award since he has greatly promoted and made significant contribution to collaboration between the School of Science at XJTU and the University of Notre Dame, in particular via the REU program, since 2013” said Prof. Fuli Li, the former Dean of School of Science at XJTU.
Professor Garg continues to support and establish the students’ exchange programs between two universities. “He introduced the Research Experience for Undergraduate Students (REU) program to our Talent Students training program, which has been of tremendous benefit to our students, providing a brilliant academic start for those students,” says Prof. Hong Gao, the current Dean of School of Science at XJTU. So far, more than 20 students from XJTU have participated in REU program, and the students’ performance has been highly commended.
“It is a great honor for me to be recognized by one of the leading universities in China, especially considering our mutual interest in Nuclear Physics and student training,” Prof. Garg said while receiving the award.