The U.S. Department of Energy (DoE) recently announced the names of 76 scientists who have been selected for their 2020 Early Career Research Program. The list includes four faculty members from MIT: Ronald Fernando Garcia Ruiz, assistant professor of physics and researcher in the Laboratory for Nuclear Science (LNS); Karthish Manthiram, assistant professor of chemical engineering; Phiala Shanahan, assistant professor of physics and researcher in the Center for Theoretical Physics within the LNS; and Wim van Rees, assistant professor of mechanical engineering.
Each year, the DoE selects researchers for significant funding "nation’s scientific workforce by providing support to exceptional researchers during crucial early career years, when many scientists do their most formative work."
The four projects submitted by MIT researchers that were chosen for this year’s program will pursue research into various aspects of fundamental physics.
Investigating exotic nuclear phenomena and fundamental symmetries of nature
Atomic nuclei with certain numbers of protons and neutrons can exhibit large variations in their nuclear density distributions. The region of actinide nuclei — nuclei with more than 88 protons — is especially interesting, as these nuclei are expected to exhibit unique pear-like nuclear shapes (octupole deformation).
The project that Department of Physics Assistant Professor Ronald Fernando Garcia Ruiz has been granted DoE funding to pursue is titled “Laser Spectroscopy of Exotic Atoms and Molecules Containing Octupole-Deformed Nuclei.” The project will focus on these nuclei and how deformation causes a large enhancement of their symmetry-violating nuclear properties. Measurements of these nuclear properties can provide answers to some of the most pressing questions of modern physics, such as the origin of the matter-antimatter asymmetry of our universe and the properties of dark matter.
Despite their importance, our experimental knowledge of these nuclei is severely lacking. Garcia Ruiz aims to perform precision laser spectroscopy experiments with atoms and molecules containing short-lived exotic actinide nuclei. This will be uniquely produced at the new Facility for Rare Isotope Beams.
“Octupole deformed nuclei are very rare, or do not exist at all, in nature. Thus, they have to be created artificially, requiring extreme environments,” explains Garcia Ruiz, whose laser laboratory in Building 24 should be completed by September. “Moreover, they can only be created in tiny quantities (typically less than 1 nanogram) and might only live for a few days or a fraction of a second. And we need to put them within an atom or a molecule to measure their properties with high precision,” he says of the major challenges to overcome with this research.
The measurements achieved from this difficult work, with the support of the DoE, will provide the molecular, atomic, and nuclear properties of exotic actinide systems, which are critical to understand the microscopic and collective structure of octupole deformed nuclei. Results will establish important benchmarks for the development of theoretical models and will constitute an essential step toward measurements of their symmetry violating properties.
Shrinking the hidden carbon footprint of everyday objects
Society is increasingly aware of the carbon footprint behind many of our typical activities. But what we are less aware of is that there is also a carbon footprint behind most chemicals and materials that we encounter everyday: the fabric of the clothes we wear, the food we eat, and the disinfectants we spray.
Karthish Manthiram, the Theodore T. Miller Career Development Chair and Assistant Professor in Chemical Engineering, is working to synthesize these chemicals and materials in a sustainable manner that eliminates the carbon footprint. With the support of the DoE Early Career Award, the Manthiram lab is specifically looking at how water can be used as a source of oxygen atoms to convert alkenes, which are two carbon atoms attached by a double bond, into an epoxide, a triangular configuration of two carbon atoms and an oxygen atom.
“The Department of Energy Office of Science has played a critical role in my own growth as a scientist,” explains Manthiram. “I was supported as a graduate student by the Department of Energy Office of Science Graduate Fellowship (DoE SCGF), which provided me with early exposure to the way in which the DoE facilitates team-based science to solve the world's most pressing energy problems, while also advancing the physical sciences.”
The chemical intermediate Manthiram is studying has one of the largest carbon dioxide footprints of any class of chemical produced today; epoxides go into manufacturing polyesters found in the fabrics of our clothing, antifreeze, and polyethylene tetrephthalate for plastic bottles, among many other products. His work will enhance not only the sustainability of this important chemical reaction by using water as a source of oxygen atoms, but also lead to safer reactions.
“With the support of a DoE Early Career Award,” says Manthiram. “I will be able to build even stronger interactions in the ecosystem fostered by the Department of Energy as we build towards electrifying and decarbonizing chemical synthesis.”
Understanding the building blocks of the universe
Atomic nuclei, built of protons and neutrons, constitute more than 99 percent of the visible mass in our universe. Quantitatively describing the structure of protons, neutrons, and nuclei in terms of their quark and gluon constituents is a defining challenge bridging hadronic and nuclear physics research.
Assistant professor of physics Phalia Shanahan’s project, “The QCD Structure of Nucleons and Light Nuclei,” is one of the approved projects to receive DoE funding. The project focuses on mapping the spatial, momentum, spin, flavor, and gluon structure of protons and neutrons. It also seeks to understand how their structures change as they form nuclei.
This research program will utilize several racks of computers at LNS’s Bates High Performance Computing Facility to undertake first-principles calculations of the strong interactions from quantum field theory. It will also develop provably exact machine learning algorithms to accelerate computations. Not only is this map the key to interpreting observations of nature in terms of the currently accepted fundamental theory, but it is also essential to inform searches for new physics.
“These calculations will deepen our understanding of nature and set benchmarks for future experiments such as those at an Electron-Ion Collider,” says Shanahan of the research that will be supported by the DoE’s 2020 award.
The results of Shanahan’s work will provide essential information for current and future nuclear physics experimental programs studying the structure of matter. It will also provide insight to those searching for violation of fundamental symmetries and new physics such as dark matter.
A new framework for solving multiphysics problems
Understanding how two domains with their own governing physics interact and influence one another is a challenge. Whether it’s a bubble in a body of water, turbulent air around a flexible airplane wing, or water striders skimming the surface of a pond — when the interface between the two domains moves and deforms, it becomes difficult to capture the physical interactions at play.
Wim van Rees, assistant professor of mechanical engineering and MIT Sea Grant Doherty Professor, is developing a new computational framework that will be able to provide accurate predictions about how two domains interact — a field known as multiphysics. The work entitled “A Multiresolution Sharp-interface Framework for Tightly coupled Multiphysics Simulations” was selected for a 2020 DoE Office of Science Early Career Research Program Award.
‘’If a flexible body interacts with a fluid flow, such as a thin sheet of paper fluttering in the wind, solving the coupling between the flow and the structure requires a very accurate representation of the boundary between the two, even as this boundary itself undergoes large motions and deformations,” van Rees explains.
For his work, which will be funded by the Office of Advanced Scientific Computing Research, van Rees is developing a multiresolution software framework that represents the interface of two domains algorithmically, independent of the geometry of the underlying computational grid.
“We want to able to deliver a computational framework for general multiphysics problems with moving interfaces,” van Rees adds, “which can be run accurately and efficiently on modern supercomputers such as the ones operated by the Department of Energy.”
de MIT News https://ift.tt/3je1kgL
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