UConn Researcher an Architect for Astronomical Survey Making Observations Toward a New Understanding of the Cosmos
November 2, 2020 – Elaina Hancock – UConn Communications 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 […]
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The passing of UConn Physics Professor Emeritus, Arnold Russek
Arnold Russek, a theoretical atomic physicist, born July 13, 1926, in New York, passed away on October 13th, 2020, in Colorado. As a young man of 18, he served honorably as a radio engineer in the Pacific during WWII. He earned his Ph.D. at the Courant Institute at New York University in 1953, and taught […]
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AAS Author Interview with Gloria Fonseca Alvarez
UConn graduate student Gloria Fonseca Alvarez was featured with a video in the Author Interview series produced by the American Astronomical Society (AAS). In this video, Gloria talks about her work to understand the inner environments of black holes. The paper highlighted in the video shows that the orbits of emission-line gas around supermassive black holes are often smaller than expected from previous observations.
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Stretching Makes Superconductor
Most superconductors only work when they’re super cold. Chemists and metallurgists have experimented with different combinations of elements for years, trying to get superconductors that work at temperatures close to room temperature. Sochnikov and his students are thinking about it differently. What if mechanical changes such as squeezing or stretching could make a material a superconductor?
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Longtime Science Pioneer Passes Away
Throughout her long life, Cynthia Peterson educated and enriched her family, her students, and her community through science, discovery, and a lifelong enthusiasm for teaching prospective scientists. Through community outreach and during her many years as a professor, Cynthia taught many that wonderment can be found simply by looking up at the night sky.
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My Long-time Friend and Colleague, Prof. Cynthia W. Peterson
When I arrived in Storrs from New York City in 1969 to teach physics at the University of Connecticut, one of the first colleagues I met was Dr. Cynthia Peterson. She had an infectious enthusiasm that appealed to me and my wife Anne. It turned out that Anne and Cynthia had both been students at […]
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New Physics Faculty: Erin Scanlon
Erin Scanlon joins our Department in fall 2020 as Assistant Professor in Residence at the Avery Point Campus. Erin comes to UConn with an impressive track record of university teaching experience and scholarship in physics education research (PER). After earning a master’s degree in physics from Georgia Institute of Technology, Erin joined the faculty at […]
[Read More]2020-Newsletter Department Head Greeting
It’s been crazy. That holds for everybody over these past six months; UConn and the Physics Department as well. Events unfurled rapidly last March. Within a week the March Meeting of the APS was cancelled, our department had to postpone the 2020 Katzenstein Lecture with Donna Strickland, and then the University announced that students would […]
[Read More]Spring 2020: The Efforts of Many Made Distance Learning Possible
The transition to online learning that was necessitated due to the COVID-19 outbreak was not without its challenges. Faculty had roughly 10 days to adapt to a modality of instruction most were not used to. TAs had to simultaneously learn how to teach remotely while also adjusting to having the courses they were taking also […]
[Read More]Physics Alum Receives NSF CAREER Award
UConn Physic alum, Dr. Hyewon Pechkis, an Assistant Professor of Physics at the California State University Chico recently received the prestigious CAREER award from the National Science Foundation. This five-year grant titled “Making a Difference in First Year Underrepresented Students’ Education through Research: Quantum Coherence in a Bose Thermal Gas” will facilitate the involvement of […]
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New Physics Faculty: Chris Faesi
We are very excited to extend a warm welcome to a new UConn Physics Faculty member, Dr. Christopher Faesi. Chris is an astrophysicist, specializing in both observational work and modelling, primarily in the study of star formation. He got his PhD at Harvard University, followed by a postdoc at the Max Planck Institute for Astronomy […]
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Prof. Kyungseon Joo named Chair of CLAS Collaboration at Jefferson Lab
Kyungseon Joo, a professor of physics, has been named Chair of the CLAS Collaboration, one of the largest international collaborations in nuclear physics. CLAS involves 50 institutions from 9 countries and has about 250 collaborators. The collaboration recently completed the upgrade of the CEBAF Large Acceptance Spectrometer (CLAS12) for operation at 11 GeV beam energy […]
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Physics Department Joins APS-IDEA Network
The Physics Department’s Diversity & Multiculturalism Committee (DMC) was accepted into the APS Inclusion, Diversity and Equity Alliance (APS-IDEA). Despite years of efforts on local and national levels, the diversity in many physics departments is not reflective of the diversity nationwide. Our department is no exception in this regard. The new APS initiative was created […]
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Professor Luchang Jin receives prestigious DOE Early Career Award
Assistant Professor of Physics Luchang Jin has been chosen to receive a prestigious Early Career Award from the US Department of Energy’s Office of High Energy Physics (HEP) for 2020. The amount of the award is $750,000 to be used over five years. The DOE Early Career Award is extremely competitive: this year only 16 scientists in […]
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Jonathan Trump wins NSF Early Career Award
Jonathan Trump, Assistant Professor of Physics, will receive $738,090 over five years to compile a census of supermassive black holes in the universe. This will give insights into how supermassive black holes and galaxies evolve across cosmic time. Trump will also develop a bridge program for underrepresented undergraduate physics majors at UConn to increase their […]
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New result for part of muon anomaly
Professors Luchang Jin and Tom Blum, along with colleagues at BNL and Columbia, Nagoya and Regensburg universities have completed a first-ever calculation of the hadronic light-by-light scattering contribution to the muon’s anomalous magnetic moment with all errors controlled. The work is published in Physical Review Letters as an Editor’s Suggestion and also appeared in Physics […]
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Radiation Damage Spreads
A single x-ray can unravel an enormous molecule, physicists report in the March 17 issue of Physical Review Letters. Their findings could lead to safer medical imaging and a more nuanced understanding of the electronics of heavy metals. Medical imaging techniques such as MRIs use heavy metals from the bottom of the periodic table as …
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Cancelled: Professor Donna Strickland , Katzenstein Distinguished Lecturer
Dear Friends of UConn Physics, Due to the current health situation and concerns surrounding the Corona virus, we are canceling the Katzenstein Lecture and Banquet scheduled for Friday, March 13, 2020. It was an agonizing decision to cancel, but our first priority is the health of all who would have been attending, our special […]
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UConn seismometer detects Puerto Rico event
The Geophysics research group (Prof. Vernon Cormier and students) operate a seismic wave station that continuously monitors vibrations in the earth’s crust, many of which arise from seismic events that happen far away. These waves travel through the deep earth, and eventually make their way to the surface where they are detected. The above […]
[Read More]2019-Newsletter Department Head Greeting
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We will have two presentations and by Los Alamos theorists:, Condensed Matter Physics Seminar9:30am
11/24
We will have two presentations and by Los Alamos theorists:, Condensed Matter Physics Seminar
Tuesday, November 24th, 2020
09:30 AM - 11:00 AM
Storrs Campus online
We will have two presentations and by Los Alamos theorists:
9:30-10:00 Shizeng Lin (Los Alamos)
Switching of valley polarization and topology in twisted bilayer graphene by electric currents
The associated manuscript is available at https://arxiv.org/abs/2002.02611.
10:00-10:30 Jian Xin Zhu (Los Alamos)
Signatures of Spin Polarized Fermi Arcs in the Quasiparticle Interferences of CeBi
Ref.: arXiv:2008.10628
10:30-11:00 Discussion
Zoom Meeting:
https://kth-se.zoom.us/j/62068067873 -
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Quantum Matter and Dark Matter Detection ", Graduate Student Seminar12:15pm
11/20
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Quantum Matter and Dark Matter Detection ", Graduate Student Seminar
Friday, November 20th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof A. Balatsky,
Department of Physics,
University of Connecticut
Dynamic Quantum Matter and Dark Matter Detection
I will give an overview of activities in the group: starting with the challenge and recent theoretical and experimental progress in identifying the dynamic and entangled orders in quantum materials. As a simple, yet new case I will describe the phenomenon of dynamic multiferroicity in STO and comment on the challenge of detection of quantum hidden orders that require multimode quantum probes. Further, I will discuss proposed applications of quantum materials outside of "usual suspect list", like the use of quantum materials as detectors for Dark Matter. -
Graduate Student Kemal Tezgin, Department of Physics, University of Connecticut, "Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions ", PhD Dissertation Defense1:00pm
11/18
Graduate Student Kemal Tezgin, Department of Physics, University of Connecticut, "Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions ", PhD Dissertation Defense
Wednesday, November 18th, 2020
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Kemal Tezgin, Department of Physics,
University of Connecticut
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions
The understanding of the internal structure of the proton and other strongly interacting particles is at the forefront of modern nuclear physics research. Generalized Parton Distribution Functions (GPDs) are a powerful tool to advance the understanding of the hadron structure. In addition to the information about the one- dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) known from studies of high energy deep-inelastic reactions, GPDs also carry information on the distribution of partons in the transverse plane, and allow us in this way to access the three-dimensional structure of the nucleon. GPDs can be studied in hard-exclusive reactions and contain also information on the energy-momentum tensor form factors which will allow us to gain insights on quantities like pressure or angular momentum distribution inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor form factors and densities, and all leading-twist GPDs in the bag model. This quark model provides a consistent theoretical framework to investigate many general concepts that have recently attracted interest, and allows one to study insightful limits like the large-Nc limit, heavy-quark limit, or the non-relativistic limit. Another important aspect of this thesis is the discussion of the monopole and quadrupole contributions to the angular momentum density. Finally, the description of pseudoscalar meson production in exclusive processes in terms of GPDs is discussed in the Goloskokov-Kroll model and implemented in the PARTONS framework, a software development project which will provide direct support for experiments at the Jefferson National Lab and the future Electron-Ion Collider. -
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions , Doctoral Dissertation Oral Defense Of Kemal Tezgin1:00pm
11/18
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions , Doctoral Dissertation Oral Defense Of Kemal Tezgin
Wednesday, November 18th, 2020
01:00 PM - 02:30 PM
Storrs Campus Zoom
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions
In high energy collisions, Parton Distribution Functions (PDFs) are fundamental objects to describe one-dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) inside the nucleon. In addition to PDFs, Generalized Parton Distribution Functions (GPDs) also carry information on the distribution of partons in the transverse plane to its motion and allow us to access the three-dimensional structure of the nucleon. On the other hand, energy-momentum tensor (EMT) densities allow us to access the pressure, shear forces, and angular momentum density inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor (EMT) form factors and densities, and all leading-twist GPDs in the bag model, formulated in the large-N_c limit. We also evaluate all leading-twist chiral-odd GPDs of the relativistic nucleon in the bag model. The consistency of this quark model allows us to investigate many general concepts that have recently attracted interest, including pressure, shear forces, and angular momentum density. Another important aspect of this thesis is to discuss that the monopole and quadrupole contributions to the angular momentum density can be generated from each other uniquely in a model-independent way. The last chapter is dedicated to the phenomenology of GPDs and the Goloskokov-Kroll model's implementation in the PARTONS framework for pseudoscalar meson production in exclusive processes. -
Dr. Vivienne Baldassare, Washington State Univeristy , "Searching for active galactic nuclei in low-mass galaxies via optical variability", Astronomy Seminar11:00am
11/18
Dr. Vivienne Baldassare, Washington State Univeristy , "Searching for active galactic nuclei in low-mass galaxies via optical variability", Astronomy Seminar
Wednesday, November 18th, 2020
11:00 AM - 12:00 PM
Storrs Campus online
Dr. Vivienne Baldassare, Washington State Univeristy
Searching for active galactic nuclei in low-mass galaxies via optical variability
The present-day population of supermassive black holes in low-mass galaxies offers a window into massive black hole formation in the early universe. While we cannot yet observe the formation of "black hole seeds" at high redshift, the fraction of small galaxies that host a supermassive black hole -- and the properties of those black holes -- are thought to depend on the mechanism by which they form. However, black holes in the smallest galaxies can be difficult to find, requiring creative new approaches. I will discuss recent work showing that long-term optical photometric variability in low-mass galaxies can identify active galactic nuclei that are missed by other selection techniques. I will present an analysis of the nuclear variability of more than 70,000 nearby galaxies and discuss our sample of low-mass, variability-selected supermassive black holes. Using this sample, we also begin to place meaningful constraints on the present-day black hole occupation fraction at low galaxy stellar masses.
Webex link: https://uconn-cmr.webex.com/meet/yah14006 -
Prof A. Puckett, Department of Physics, University of Connecticut, Graduate Student Seminar12:15pm
11/13
Prof A. Puckett, Department of Physics, University of Connecticut, Graduate Student Seminar
Friday, November 13th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof A. Puckett,
Department of Physics,
University of Connecticut
Sub-femtoscale structure of strongly interacting matter from "hard" electron-nucleus collisions
The emergence of nucleon structure and dynamics from strong interactions among its elementary quark and gluon constituents is one of the most difficult and interesting problems in all of physics. The strong interaction, NOT the electroweak Higgs mechanism, is responsible for the dynamical generation of the mass of approximately 98% of all ordinary matter in the universe. Scattering of ultrarelativistic electron beams from nucleon and nuclear targets is the tool of choice for the precision study of nucleon structure. The Super BigBite Spectrometer (SBS) at Jefferson Lab, a novel device currently being installed in JLab's experimental Hall A, with the first beam tentatively expected in 2021, will facilitate a focused program of high-impact nucleon structure measurements in electron-nucleon scattering at large momentum transfer. In this talk I will give an overview of the upcoming SBS program and opportunities for graduate student involvement. -
Professor Saroj Prasad Dash, Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Sweden, "Spin Current in Topological Quantum Materials", Condensed Matter Physics Seminar10:00am
11/10
Professor Saroj Prasad Dash, Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Sweden, "Spin Current in Topological Quantum Materials", Condensed Matter Physics Seminar
Tuesday, November 10th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Professor Saroj Prasad Dash,
Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience,
Chalmers University of Technology, Sweden
Spin Current in Topological Quantum Materials
An outstanding feature of topological quantum materials is their unique spin topology in the electronic band structures with an expected novel charge‐to‐spin conversion effects. In the Weyl semimetal candidate WTe2 we observed both conventional1 and unconventional2 charge‐to‐spin conversion effects at room temperature. In addition to the conventional spin Hall and Rashba--Edelstein effects, we also measured an unconventional charge‐to‐spin conversion component in WTe2. Such a large spin polarization can be possible in WTe2 due to a reduced crystal symmetry combined with its large spin Berry curvature, spin--orbit interaction with a novel spin‐texture of the Fermi states. We also investigated giant Rashba spin-orbit materials BiTeBr to detect the current induced spin polarization at room temperature.3 Furthermore, we integrated graphene with a topological insulator4,5 in van der Waals heterostructures6 to engineer proximity-induced spin-charge conversion phenomena. In these heterostructures, we experimentally demonstrate a gate-tunable spin-galvanic effect at room temperature, allowing for efficient conversion of a non-equilibrium spin polarization into a transverse charge current.7 These findings provide an efficient route for realizing all-electrical and gate-tunable spin phenomenon in topological materials and their heterostructures.
References:
1. Observation of charge to spin conversion in Weyl semimetal at room temperature.
B Zhao, D Khokhriakov, Y Zhang, H Fu, B Karpiak, AM Hoque, X Xu, Y Jiang, B Yan, SP Dash.
Physical Review Research 2 (1), 013286 (2020).
2. Unconventional charge-to-spin conversion Weyl Semimetal WTe2. B Zhao, B Karpiak, D Khokhriakov, A Johansson, AM Hoque, X Xu, Y Jiang, I Mertig, SP Dash. Advanced Materials, 2000818 (2020).
3. Electrically controlled spin injection from giant Rashba spin-orbit conductor BiTeBr"
Z Kovács-Krausz et al., Nano Letters 20, 7, 4782--4791 (2020).
4. Origin and evolution of surface spin current in topological insulators
A Dankert, P Bhaskar, D Khokhriakov, IH Rodrigues, B Karpiak, MV Kamalakar, S Charpentier, I Garate, SP Dash.
Phys. Rev. B 97, 125414 (2018).
5. Room Temperature Electrical Detection of Spin Polarization in Topological Insulators
A Dankert, J. Geur, M.V. Kamalakar, SP Dash;
Nano Letters 15 (12) 7976 (2015).
6. Tailoring emergent spin phenomena in Dirac material heterostructures.
D Khokhriakov, A. W. Cummings, K Song, M Vila, B Karpiak, A Dankert, S Roche and SP. Dash.
Science Advances, 4, 9, eaat9349 (2018)
7. Gate-tunable Spin-Galvanic Effect in Graphene - Topological insulator van der Waals Heterostructures at Room Temperature. D Khokhriakov, AM Hoque, B Ka -
Jacob Franklin, Department of Physics, University of Connecticut, "Quantum sensing for nanoscale magnetic imaging", Graduate Student Seminar12:15pm
11/6
Jacob Franklin, Department of Physics, University of Connecticut, "Quantum sensing for nanoscale magnetic imaging", Graduate Student Seminar
Friday, November 6th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Jacob Franklin,
Department of Physics,
University of Connecticut
Quantum sensing for nanoscale magnetic imaging
Nanoscale resolution of the properties of materials often plays a crucial role in the pursuit of explanations for exotic phenomena in such materials. These phenomena, such as high temperature superconductivity and frustrated magnetic states, have very exciting potential for practical applications, such as quantum computing. In the Sochnikov Lab, we use state-of-the-art sensors called SQUIDs to probe the magnetic properties of materials and generate magnetic maps at their surfaces. These images are on the order of micrometers in spatial resolution and play an important role in the study of the aforementioned phenomena, for example, because they can be used to analyze the formation and interaction of domains in response to parameters like temperature, auxiliary magnetic field, or strain. I will present some of the fundamental materials research work I have done in the Sochnikov Lab, in which I and my lab mates have taken a direct role in both measurement and analysis. In addition, I will share my experience with instrumentation development projects like the construction of custom-built piezoelectric scanners, the improvement of wiring in our cryostats, the coding of a GUI system for the plotting of data, and the improvement of our data interpolation functions. -
Mohammad Akhshik, Department of Physics, University of Connecticut, "REQUIEM-2D: REsolving QUIEscent Magnified galaxies using strong gravitational lensing, 2D grism spectroscopy and multi-band photometry", Astronomy Seminar10:00am
11/4
Mohammad Akhshik, Department of Physics, University of Connecticut, "REQUIEM-2D: REsolving QUIEscent Magnified galaxies using strong gravitational lensing, 2D grism spectroscopy and multi-band photometry", Astronomy Seminar
Wednesday, November 4th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Mohammad Akhshik, Department of Physics, University of Connecticut
REQUIEM-2D: REsolving QUIEscent Magnified galaxies using strong gravitational lensing, 2D grism spectroscopy and multi-band photometry
Despite the tremendous progress that has been made in the last decade in studying massive high redshift (z~2) quiescent galaxies, their formation pathways and quenching mechanisms have not yet been established observationally. In my talk, I will review the REQUIEM^2D galaxy survey of eight strong lensed quiescent galaxies at z=1.6-2.9, our attempt to understand the formation scenarios of quiescent galaxies by analyzing the spatially resolved stellar populations with deep HST grism spectroscopy. After briefly reviewing our methodology, I will discuss the results from our REQUIEM^2D pilot target, MRG-S0851, a gravitationally lensed quintuply imaged massive compact red galaxy at z=1.9. Using our recovered ages and SFHs from the joint spectrophotometric analysis, along with trajectories in the UVJ and FUVVJ color-color diagrams, I show that MRG-S0851 is consistent with an early forming, slow quenched galaxy that is going through a centrally-concentrated rejuvenation phase.
Dr. Daniel Walker, Department of Physics, University of Connecticut
Uncovering the hidden star formation in the Milky Way's Central Molecular Zone
As our nearest "extreme environment", the Central Molecular Zone (CMZ, inner few hundred parsecs of our Galaxy) offers an ideal laboratory in which to study the extent to which the process of star formation is sensitive to differing environmental conditions. At a distance of just 8.1 kpc, we can study this process from Galactic scales all the way down to protostellar scales, something that is not possible in extragalactic analogues. In this talk, I will give an overview of our current understanding of star formation in this region of the Galaxy. I will then present some results from recent and ongoing projects that are transforming our view of the CMZ, and providing insight into key questions concerning the role of galactic environment in the star formation process.
Meeting Link: https://uconn-cmr.webex.com/meet/cab16109 -
Prof Jeremy Levy, Department of Physics and Astronomy, University of Pittsburgh, "Ferroelastic Textures, Magnetism, and Superconductivity in LaAlO3/SrTiO3", Condensed Matter Physics Seminar10:00am
11/3
Prof Jeremy Levy, Department of Physics and Astronomy, University of Pittsburgh, "Ferroelastic Textures, Magnetism, and Superconductivity in LaAlO3/SrTiO3", Condensed Matter Physics Seminar
Tuesday, November 3rd, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Prof Jeremy Levy, Department of Physics and Astronomy, University of Pittsburgh
Ferroelastic Textures, Magnetism, and Superconductivity in LaAlO3/SrTiO3
LaAlO3/SrTiO3 heterostructures exhibit a wide range of phenomena that are not well understood. The most prominent are the existence of superconductivity at very low densities, which has been known for more than half a century, and magnetism, which is a more recent discovery. Here I will review experiments that directly probe and/or control these effects at nanoscale dimensions, and suggest that there are strong couplings between ferroelastic domain structure (texture) in LaAlO3/SrTiO3 and both magnetism and superconductivity. I will also examine a connection between some reports of magnetism in transport experiments and phenomena related to superconductivity.
Zoom Meeting:
https://kth-se.zoom.us/j/69230357179 -
Profs. Gerald Dunne and Jon Trump, Department of Physics, University of Connecticut, "Black Holes: The 2020 Nobel Prize in Physics", The 2020 Nobel Prize In Physics (Physics Department Colloquium)3:30pm
10/30
Profs. Gerald Dunne and Jon Trump, Department of Physics, University of Connecticut, "Black Holes: The 2020 Nobel Prize in Physics", The 2020 Nobel Prize In Physics (Physics Department Colloquium)
Friday, October 30th, 2020
03:30 PM - 04:30 PM
Storrs Campus online
Profs. Gerald Dunne and Jon Trump, Department of Physics, University of Connecticut
Black Holes: The 2020 Nobel Prize in Physics
The Nobel Foundation has awarded the 2020 Nobel Prize in Physics to Roger Penrose "for the discovery that black hole formation is a robust prediction of the general theory of relativity", and to Reinhard Genzel and Andrea Ghez "for the discovery of a supermassive compact object at the centre of our galaxy".
See https://www.nobelprize.org/prizes/physics/2020/summary/
We review the physics and the significance of these remarkable discoveries. There will be some technical detail but the talk is intended for a general audience.
Webex link: https://uconn-cmr.webex.com/meet/jot16106 -
Dr. Bradford Snios, Harvard-Smithsonian Center for Astrophysics, "Kinematics of extragalactic jets", Graduate Student Seminar12:15pm
10/30
Dr. Bradford Snios, Harvard-Smithsonian Center for Astrophysics, "Kinematics of extragalactic jets", Graduate Student Seminar
Friday, October 30th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Dr. Bradford Snios, Harvard-Smithsonian Center for Astrophysics
Kinematics of extragalactic jets
Extragalactic jets emitted from active galactic nuclei are a well-established phenomenon. These jets are known to propagate with bulk relativistic motion over kiloparsec-scale distances, generating emission across multiple energy bands, including the X-ray. In my talk, I will discuss recent X-ray observations investigated for proper motions and brightness changes in nearby jets. Using multi-epoch observations spanning several years, proper motions from X-ray emission are detected for the first time in extragalactic systems, with superluminal motions measured up to speeds of 6.3c. Brightness variations up to 73% are found for the X-ray knots in the jets, and spectroscopic modeling is used to determine cooling emission mechanisms from the sources. These results provide invaluable constraints on the kinematic evolution of these exotic extragalactic systems. -
Prof. Elena Dormidontova, Department of Physics, University of Connecticut, "Soft Matter Physics: HPC Simulations and Theory", Graduate Student Seminar12:15pm
10/23
Prof. Elena Dormidontova, Department of Physics, University of Connecticut, "Soft Matter Physics: HPC Simulations and Theory", Graduate Student Seminar
Friday, October 23rd, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. Elena Dormidontova,
Department of Physics,
University of Connecticut
Soft Matter Physics: HPC Simulations and Theory
Soft matter includes a broad range of structurally different materials ranging from small molecules such as lipids and liquids crystals to macromolecules, biopolymers and colloids. These materials can self-assemble into different organized structures and possess properties which vary depending on external conditions. To be able to understand the principles of self-assembly, predict and direct the outcomes of it is highly desirable to gain fundamental insight into biological self-assembly and to be able to create new materials with desired properties for energy, photonic, nanoelectronics, nanomedicine, sensors and other advanced functional nanomaterials. Theory and molecular modeling play an increasingly important role in gaining fundamental insights into complex behavior of these systems, as it allows to achieve atomistic level details inaccessible experimentally or guide experimental material development by predicting self-assembly pathways depending on structural properties of the building elements and external conditions. Several examples of ongoing, recently funded and planned interdisciplinary research projects collaboration with experimental groups will be discussed in connection with corresponding computer modeling approaches and material applications. -
Prof. Erin Scanlon, Department of Physics, University of Connecticut, "An Introduction to Physics Education Research", Graduate Student Seminar12:15pm
10/16
Prof. Erin Scanlon, Department of Physics, University of Connecticut, "An Introduction to Physics Education Research", Graduate Student Seminar
Friday, October 16th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. Erin Scanlon,
Department of Physics,
University of Connecticut
An Introduction to Physics Education Research
Physics education research (PER) is a subfield of physics that focuses on investigating questions such as: 1) how can we teach physics better?; 2) how do students learn physics?; and 3) how can we make the physics community more inclusive, equitable, and diverse? In this talk, we will give an introduction to PER, including common misconceptions, methods, and the PER happening at UConn. -
Dr. Viktor Mokeev, Jefferson National Laboratory, "Advances in the Exploration of the Nucleon Resonance Spectrum and Structure in Experimentswith CLAS and CLAS12", Particle, Astrophysics, And Nuclear Physics Seminar2:00pm
10/12
Dr. Viktor Mokeev, Jefferson National Laboratory, "Advances in the Exploration of the Nucleon Resonance Spectrum and Structure in Experimentswith CLAS and CLAS12", Particle, Astrophysics, And Nuclear Physics Seminar
Monday, October 12th, 2020
02:00 PM - 03:00 PM
Storrs Campus online
Dr. Viktor Mokeev, Jefferson National Laboratory
Advances in the Exploration of the Nucleon Resonance Spectrum and Structure in Experimentswith CLAS and CLAS12
Studies of nucleon resonances (N*) in experiments with electromagnetic probes offer unique information on many facets of the strong interaction in the regime of large (on the order of unity) QCD running couplings seen in the generation of the spectrum of N* states with different quantum numbers and structural features. The current status of the N* spectrum and structure studies for exclusive meson photo- and electro-production data with CLAS at Jefferson Lab will be presented in the talk. The extension of these efforts in the Jefferson Lab 12 GeV-era experiments with CLAS12 will be outlined.
WebEx Meeting: https://uconn-cmr.webex.com/uconn-cmr/j.php?MTID=mb3e4c57467ee718677987ca3a427a21d -
Dr. James Guillochon, Berkshire Gray, "From Black Holes, to Data Science, to Robots: Tips & tricks for going into industry", Physics Colloquium: From Black Holes To Robots3:30pm
10/9
Dr. James Guillochon, Berkshire Gray, "From Black Holes, to Data Science, to Robots: Tips & tricks for going into industry", Physics Colloquium: From Black Holes To Robots
Friday, October 9th, 2020
03:30 PM - 04:30 PM
Storrs Campus BPB-131
Dr. James Guillochon, Berkshire Gray
From Black Holes, to Data Science, to Robots: Tips & tricks for going into industry
The majority of physics/astronomy PhD recipients now leave the field for industry either immediately after graduation or after one or more postdoctoral stints. This has been driven by several factors, including the overproduction of PhDs relative to a declining pool of available tenure-track positions, greater freedom to choose where to live, and often significantly higher salaries. However, STEM graduates are increasingly finding that data science, the de facto refuge for former academics, is itself becoming somewhat saturated, with data on recent job listings suggesting that the majority of DS positions are now filled by bachelor's degree recipients rather than PhDs. In this talk, I will describe how I navigated this increasingly complicated landscape to find my current job, and share some pieces of advice I feel are generically useful to those who might be looking for jobs outside of academia in the next few years.
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Dr. James Guillochon received a PhD in astrophysics from the University of California Santa Cruz and then went on to hold prestigious postdoctoral fellowships, the Hubble and ITC fellowships, at the Harvard-Smithsonian Center for Astrophysics. He developed a reputation as a world-renowned researcher in a range of topics, including black hole mergers, tidal disruption events, white dwarf accretion, and more. He is also well-known for his open-source contributions to the scientific community, including vox charta, open access astronomy catalogs, software, as well as maintaining a current list of US and Canadian astrophysics graduate program policies regarding the use of the physics GRE in graduate admissions decisions here.
In 2018 Dr. Guillochon transitioned to working in the industry as a Robotics Engineer in the Boston area. He is an outspoken advocate for positive transitions from academia to industry and will be joining us for a virtual colloquium on Friday to discuss his transition. -
Dr. Hossein Sadeghpour, Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics, "Quantum electron scattering", Graduate Student Seminar12:15pm
10/9
Dr. Hossein Sadeghpour, Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics, "Quantum electron scattering", Graduate Student Seminar
Friday, October 9th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Dr. Hossein Sadeghpour,
Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center for Astrophysics
Quantum electron scattering
The second quantum revolution is upon us and atomic molecular and optical (AMO) physics is the discipline leading this revolution. Major advances in cooling and trapping of atoms and molecules in the last three decades now allow practitioners to create exotic many-body systems whose properties and behavior are predicated on fluctuations inherent in quantum systems. The ultracold AMO systems can be precisely and exquisitely interrogated and manipulated to engineer few-body interactions that "nature" may not naturally provide. I'll draw on some fundamental physics concepts to elucidate a few of these quantum many-body features. -
Dr. Semeon Valgushev, Brookhaven National Lab, "Phase diagram of QCD and Lifshitz regime: how transverse thermal fluctuations might turn nuclear matter into quantum-spin liquid", Particle, Astrophysics, And Nuclear Physics Seminar2:00pm
10/5
Dr. Semeon Valgushev, Brookhaven National Lab, "Phase diagram of QCD and Lifshitz regime: how transverse thermal fluctuations might turn nuclear matter into quantum-spin liquid", Particle, Astrophysics, And Nuclear Physics Seminar
Monday, October 5th, 2020
02:00 PM - 03:00 PM
Storrs Campus online
Dr. Semeon Valgushev, Brookhaven National Lab
Phase diagram of QCD and Lifshitz regime: how transverse thermal fluctuations might turn nuclear matter into quantum-spin liquid
We discuss dense cool QCD where a region with spatially inhomogeneous condensate might emerge. In that case, QCD phase diagram may exhibit a Lifshitz regime, which can appear either instead of, or in addition to Critical End Point. We study the Lifshitz regime using a combination of large-N expansion and numerical lattice simulations of an effective O(N) sigma model. We find evidence that quantum fluctuations disorder inhomogeneous condensate ("chiral spirals") and give rise to unusual quantum spin-liquid phase. We also discuss how this novel phase can be detected experimentally.
Zoom Meeting Link:
https://us02web.zoom.us/j/8192648596?pwd=WFkzK1VXa2V4ZVRVNC90ZnM3NDdlQT09
Meeting ID: 819 264 8596
Passcode: 9lYjMG
Note: The seminar will start at 2:00PM, but participants are welcomed to join the meeting at 1:30PM for discussion. -
Prof. M. Gai, Department of Physics, University of Connecticut, "Oxygen Formation in Stellar Helium Burning", Graduate Student Seminar12:15pm
10/2
Prof. M. Gai, Department of Physics, University of Connecticut, "Oxygen Formation in Stellar Helium Burning", Graduate Student Seminar
Friday, October 2nd, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. M. Gai, Department of Physics, University of Connecticut
Oxygen Formation in Stellar Helium Burning
The Laboratory for Nuclear Science (LNS) at Avery Point (http://astro.uconn.edu), aka the Laboratory for Astrophysics, is engaged in research of several problems central to stellar Evolution theory. Today we shall discuss oxygen formation is stellar helium burning, that determines the C/O ratio in stars. This is an essential laboratory input to stellar evolution theory that for example determines the final fate of a Type II supernova (black hole or neutron star), as well as the light curve of a Type Ia supernova (that is used to measure distances to the end of the observable universe from which the accelerated expansion of the universe was recently discovered).
This presentation will involve our faculty at Avery Point (Gai) and in the UK (Smith) and the two graduate students (Stern and Schweitzer) who are working on experiments at Duke University in the USA, in Warsaw, Poland, and in a new facility constructed in Romania. -
Prof. Richard Milner MIT, Physics Colloquium: Visualizing The Proton3:30pm
9/25
Prof. Richard Milner MIT, Physics Colloquium: Visualizing The Proton
Friday, September 25th, 2020
03:30 PM - 04:30 PM
Storrs Campus Remote
Prof. Richard Milner
MIT
Abstract:
Nuclear physicists have recently made progress in understanding how to visualize the fundamental structure of the proton. Electrons scattered from the proton's charged constituents produce snapshots that offer the possibility to produce for the first time a coherent 3D image of the proton. The basic
elements of the technique will be outlined and ongoing experiments at Jefferson Laboratory as well as future experiments at the planned Electron-Ion Collider (EIC) at Brookhaven Laboratory will be described.
Remote Connection info:
TBA -
Graduate Student Benjamin Commeau, Department of Physics, University of Connecticut, "Two Studies on Topological Properties of Organic Superconductors and a new Quantum Dynamical Simulation Algorithm", PhD Dissertation Defense2:00pm
9/25
Graduate Student Benjamin Commeau, Department of Physics, University of Connecticut, "Two Studies on Topological Properties of Organic Superconductors and a new Quantum Dynamical Simulation Algorithm", PhD Dissertation Defense
Friday, September 25th, 2020
02:00 PM - 04:00 PM
Storrs Campus Video meeting
Graduate Student Benjamin Commeau, Department of Physics,
University of Connecticut
Two Studies on Topological Properties of Organic Superconductors and a new Quantum Dynamical Simulation Algorithm
In this thesis I investigate two research topics in topological organic superconductors and one research topic in variational algorithms for quantum computation.
In the first chapter we investigate the structural and electronic properties of the three structural phases alpha, beta and kappa of (BEDT-TTF)2I3, by performing state of the art ab initio calculations in the framework of density functional theory. We furthermore report about the irreducible representations of the corresponding electronic band structures, symmetry of their crystal structure, and discuss the origin of band crossings.
Additionally, we discuss the chemically induced strain in kappa-(BEDT-TTF)2I3 achieved by replacing the iodine layer with other Halogens: Fluorine, Bromine and Chlorine. In the case of kappa-(BEDT-TTF)2F3, we identify topologically protected crossings within the band structure. These crossings are forced to occur due to the non-symmorphic nature of the crystal. In the second chapter, we performed structural optimization and electronic structure calculations in the framework of density functional theory, incorporating, first, the recently developed strongly constrained and appropriately normed semilocal density functional SCAN, and, second, van der Waals corrections to the PBE exchange correlation functional by means of the dDsC dispersion correction method.
In the case of alpha-(BEDT-TTF)2F3 the formation of over-tilted Dirac-type-II nodes within the quasi 2-dimensional Brillouin zone can be found.
For kappa-(BEDT-TTF)2F3, the recently reported topological transition within the electronic band structure cannot be revealed. In the third chapter, we propose a new algorithm called Variational Hamiltonian Diagonalization (VHD), which approximately transforms a given Hamiltonian into a diagonal form that can be easily exponentiated. VHD allows for fast forwarding, and removes Trotterization error and allows simulation of the entire Hilbert space. We prove an operational meaning for the VHD cost function in terms of the average simulation fidelity. Moreover, we prove that the VHD cost function does not exhibit a shallow-depth barren plateau. Our numerical simulations verify that VHD can be used for fast-forwarding dynamics.
Zoom Link: https://harvard.zoom.us/j/92203325795?pwd=T2VoYzNPNkwvZW1GWFlhQk9Ga1lwUT09 -
Prof. T. Blum, Department of Physics, University of Connecticut, "Lattice QCD at UConn", Graduate Student Seminar12:15pm
9/18
Prof. T. Blum, Department of Physics, University of Connecticut, "Lattice QCD at UConn", Graduate Student Seminar
Friday, September 18th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. T. Blum, Department of Physics, University of Connecticut
Lattice QCD at UConn
I will give a brief introduction to the Standard Model of Particle Physics, and Quantum Chromodynamics (QCD) in particular. I will then describe how we solve QCD using large scale numerical simulations. I will finish with a few current and important examples. -
Graduate Student Saman Bastami, Department of Physics, University of Connecticut, "Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions", PhD Dissertation Defense1:15pm
9/11
Graduate Student Saman Bastami, Department of Physics, University of Connecticut, "Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions", PhD Dissertation Defense
Friday, September 11th, 2020
01:15 PM - 03:15 PM
Storrs Campus Video meeting
Graduate Student Saman Bastami, Department of Physics,
University of Connecticut
Studies on Hadron Structure through Transverse-Momentum-Dependent Parton Distribution Functions
The detailed description of hadrons in terms of quarks and gluons, the fundamental degrees of freedom of Quantum Chromodynamics, is an open problem. Important aspects of hadron structure can be studied in certain deep-inelastic high-energy processes which have revealed important insights about the longitudinal momentum distributions of quarks and gluons inside hadrons. Our knowledge of the three-dimensional structure is still very limited. Transverse momentum dependent parton distribution functions (TMDs) are one of the main tools to study the transverse structure of hadrons through processes such as semi-inclusive deep inelastic scattering SIDIS) or the Drell-Yan process. This dissertation is dedicated to phenomenological and model studies of TMDs.
All spin and azimuthal asymmetries of the lepton-nucleon SIDIS are calculated at leading- and subleading twist exploring the so-called "Wandzura-Wilczek-type" approximation which consists in a systematic neglect quark-gluon correlations. The results are obtained using available phenomenological information on TMDs as well as constraints from state-of-the-art lattice QCD calculations, and compared to the experimental data from HERMES, COMPASS and Jefferson Lab.
The asymmetries of the pion-induced Drell-Yan process with polarized protons are studied at leading twist. The information about TMDs is taken from non-perturbative calculations in the lightfront constituent quark model, the spectator model and, where available, phenomenological extractions of TMDs. The results are compared to recent data from the first polarized pion-nucleon Drell-Yan experiment performed by the COMPASS Collaboration at CERN, and predictions for future experiments are made.
The "covariant parton model", an effective hadronic model based on the intuitive parton model concept, is extended and formalized. This allows one to compute all time-reversal-even TMDs of leading and subleading twist in a systematic way. This model naturally supports the Wandzura-Wilczek-type approximations and predicts several non-trivial relations between TMDs, many of which are supported in other model frameworks and can be tested in experiments. Applications and limitations of the model are discussed.
Meeting video link: https://zoom.us/j/96866754697?pwd=NEM1WUt3VkxhbVdQQWdacVVubHNvQT09 -
Prof. D. McCarron, Department of Physics, University of Connecticut, "A quantum-leap towards next generation technologies", Graduate Student Seminar12:15pm
9/11
Prof. D. McCarron, Department of Physics, University of Connecticut, "A quantum-leap towards next generation technologies", Graduate Student Seminar
Friday, September 11th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof. D. McCarron, Department of Physics, University of Connecticut
A quantum-leap towards next generation technologies
Recent progress manipulating quantum systems has led to a second quantum revolution that is developing new technologies that leverage the laws of nature at small scales. This talk will give an overview of some of these new technologies alongside their applications - with an emphasis on ultracold systems cooled to one millionth of a degree above absolute zero. I will draw links between these applications and my own research program before giving a brief summary of our experimental progress.
Research Group URL: http://themccarrongroup.com -
Doctoral Dissertation Oral Defense of Saman Bastami1:30pm
9/7
Doctoral Dissertation Oral Defense of Saman Bastami
Monday, September 7th, 2020
01:30 PM - 03:00 PM
Other Zoom
Studies on Hadron Structure through Transverse Momentum Dependent Parton Distribution Functions -
Graduate Student Brandon A. Clary, Department of Physics, University of Connecticut, "Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12", PhD Dissertation Defense9:30am
8/21
Graduate Student Brandon A. Clary, Department of Physics, University of Connecticut, "Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12", PhD Dissertation Defense
Friday, August 21st, 2020
09:30 AM - 11:30 AM
Storrs Campus Video meeting
Graduate Student Brandon A. Clary, Department of Physics,
University of Connecticut
Exclusive Phi Production Beam Spin Asymmetry Measurements with CLAS12
Measurements of the beam spin asymmetry (BSA) of the exclusive electroproduction of the vector phi(1020) meson through its decay into charged Kaons have been performed. The data set used was based on the RG-A run period from the recently upgraded CEBAF Large Acceptance Spectrometer (CLAS12) in Hall B at Jefferson National Lab (JLab). The run period used a 10.6 GeV longitudinally polarized electron beam and an unpolarized hydrogen target. The available statistics collected allow for detailed studies of the W, -t, xB, and Q2 dependencies of the BSA amplitudes from vector phi meson production. The BSA measurements will shed light on the exchange mechanisms responsible for phi production at JLab energies. In this dissertation, a non-zero BSA is observed, which suggests a possible enhancement of pseudo-scalar exchange mechanism near phi production threshold. Therefore, the non-zero BSA may be a result of the interference of the pseudo-scalar exchange mechanism with a scalar one. Ultimately, information on the dominant exchange mechanism will aid in the development of a Generalized Parton Distribution (GPD) based description of these processes in the context of hard to soft transition.
Webex link: https://uconn-cmr.webex.com/uconn-cmr/j.php?MTID=m0844eee0d13477ad76f35797ae8467db -
Dr. D. Farfurnik, University of Maryland, "Enhancing the coherence properties of quantum dots toward quantum photonic applications", Condensed Matter Physics Seminar10:00am
7/14
Dr. D. Farfurnik, University of Maryland, "Enhancing the coherence properties of quantum dots toward quantum photonic applications", Condensed Matter Physics Seminar
Tuesday, July 14th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Dr. D. Farfurnik, University of Maryland
Enhancing the coherence properties of quantum dots toward quantum photonic applications
Self-assembled Quantum Dots (QD) exhibit some of the best single photon emission properties, including nearly ideal efficiency and indistinguishability. As such, and considering their compatibility with nanofabrication techniques, on-chip integration of QDs as single photon emitters and non-linear components plays a key role in integrated photonic-based information processing and may pave the way toward the creation of quantum networks. Manipulating and storing quantum information utilizing QD spins, however, is limited by their short coherence times originating from interactions with a nuclear bath. In this talk, I will describe our approaches for addressing this challenge: First, the application of dynamical decoupling (DD) pulse sequences prolongs the coherence times by decoupling the QD spins from the environment. While the performance of such protocols is often limited by the accumulation of pulse imperfections, arbitrary spin control enabling composite and concatenated sequencing could further enhance the achievable spin control fidelities [1]. Such a sequencing is implementable by driving a Lambda system of the QD utilizing an optical signal arbitrarily modulated by a temperature-stabilized electro optical modulator (EOM). I will present a recent experimental demonstration of such a control [2], our analysis for optimizing the EOM working point for enhancing the achievable optical rotation Rabi frequencies, as well as the efficiency of the protocol for QDs strongly coupled to L3 photonic crystal cavities. Second, the resulting coherence properties may be further enhanced by utilizing molecules of coupled QDs (QDM), which offer a singlet-triplet ground state decoherence-free subspace [3]. Beyond the promising combination of such a subspace with the application of DD sequences, leveraging the isolated optical transitions of the QDM may offer single-shot spin readout capabilities. I will present our approach for implementing such a spin readout incorporating microwave pi-pulses, its experimental feasibility utilizing optimally designed transmission lines, and the expected readout fidelities based on the achievable microwave Rabi frequencies [4].
[1] D. Farfurnik et al., ``Optimizing a dynamical decoupling protocol for solid-state electronic spin ensembles in diamond'', Phys. Rev. B 92, 060301(R) (2015)
[2] J.H. Bodey et al., ``Optical spin locking of a solid-state qubit'', npj Quantum Information 5, 95 (2019)
[3] D. Kim et al., ``Ultrafast optical control of entanglement between two quantum-dot spins'', Nat. Phys. 7, 223--229 (2011)
[4] D. Farfurnik et al., ``Experimental realization of time-dependent phase-modulated continuous dynamical decoupling'', Phys. Rev. A 96, 013850 (2017)
Zoom Meeting: https://kth-se.zoom.us/j/61809414846 -
Graduate Student Daniel McNeel, Department of Physics, University of Connecticut, "Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus", PhD Dissertation Defense1:00pm
6/11
Graduate Student Daniel McNeel, Department of Physics, University of Connecticut, "Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus", PhD Dissertation Defense
Thursday, June 11th, 2020
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Daniel McNeel, Department of Physics,
University of Connecticut
Shape Coexistence in \(^{28}\)Mg: Structure of a Transitional Nucleus
The structure of nuclei outside the region of stability is an area of ongoing experimental research. Recent investigations in the region around \(^{32}\)Mg have discovered inversions in the usual ordering of shell model states. From these discoveries, theories of the evolution towards this "island of inversion" predict low-lying deformed intruder states for several nuclei in the region. One such nucleus, which exists in the region of transition between the normal and inverted hierarchies, is \(^{28}\)Mg. In this nucleus the ground state is expected to be mixed, i.e. it is a superposition of nearby \(0^+\) neutron pairing configurations. An excited intruder \(0^+\) state will have a different configuration and shape than surrounding states, a property known as shape coexistence.
Multi-nucleon transfer is known to be sensitive to the static deformation of a nucleus. It is also sensitive to both the amplitude and phase of configuration mixed states, and enhances transfer to those states which are similar to the ground state of the target plus two nucleons in single particle orbitals. This makes it a valuable tool to investigate the properties of \(^{28}\)Mg. The two-neutron adding reaction \(^{26}\)Mg(t,p)\(^{28}\)Mg has been used to study the properties of the ground state and excited \(0^+\) states. This experiment was carried out at Argonne National Laboratory using the HELIcal Orbit Spectrometer (HELIOS). HELIOS was designed to overcome the difficulties of measuring reactions in inverse kinematics. Experiments in inverse kinematics consist of a heavy particle, in this case \(^{26}\)Mg, incident on the light particle (\(^3\)H).
Because multi-nucleon transfers are more complex than single particle transfers, a calculation of the nuclear structure must guide the understanding of which configurations will be strongly populated. Shell model calculations have been used to evaluate the structure related transfer amplitudes, which were used as input into Distorted Wave Born Approximation (DWBA) calculations for the reaction. The results of this analysis are the relative contributions of different configurations to the ground state and excited \(0^+\) states, which provide a stringent test of the theoretical prediction of shape coexistence and intruder states.
Video link: https://uconn-cmr.webex.com/meet/dgm14002 -
Graduate Student Matthew Phelps, Department of Physics, University of Connecticut, "Cosmological Fluctuations in Standard and Conformal Gravity", PhD Dissertation Defense10:00am
6/2
Graduate Student Matthew Phelps, Department of Physics, University of Connecticut, "Cosmological Fluctuations in Standard and Conformal Gravity", PhD Dissertation Defense
Tuesday, June 2nd, 2020
10:00 AM - 12:00 PM
Storrs Campus Video meeting
Graduate Student Matthew Phelps, Department of Physics,
University of Connecticut
Cosmological Fluctuations in Standard and Conformal Gravity
In the theory of cosmological perturbations, extensive methods of simplifying the equations of motion and eliminating non-physical gauge modes are required in order to construct the perturbative solutions. One approach, standard within modern cosmology, is to decompose the metric perturbation into a basis of scalars, vectors, and tensors defined according to their transformation behavior under three-dimensional rotations (the S.V.T. decomposition). By constructing a projector formalism to define the basis components, we show that such a decomposition is intrinsically non-local and necessarily incorporates spatially asymptotic boundary conditions. We continue application of the S.V.T. decomposition and solve the fluctuation equations exactly within standard cosmologies as applied to both Einstein gravity and conformal gravity, finding that in general the various S.V.T. gauge-invariant combinations only decouple at a higher-derivative level. To match the underlying transformation group of General Relativity and thus provide a manifestly covariant formalism, we introduce an alternate scalar, vector, tensor basis with components defined according to general four-dimensional coordinate transformations. In this basis, the fluctuation equations greatly simplify, where one can again decouple them into separate gauge-invariant sectors at the higher-derivative level. In the context of conformal gravity, we use similar constructions to solve the fluctuation equations exactly within any geometry that is conformal to flat and show that in a radiation era Robertson-Walker cosmology, fluctuations grow as \(t^4\).
Video Meeting URL: https://uconn-cmr.webex.com/meet/map14010 -
Prof. Chiara Mingarelli, Department of Physics, University of Connecticut, "Probing supermassive black hole mergers with pulsar timing", Graduate Student Seminar12:15pm
4/24
Prof. Chiara Mingarelli, Department of Physics, University of Connecticut, "Probing supermassive black hole mergers with pulsar timing", Graduate Student Seminar
Friday, April 24th, 2020
12:15 PM - 01:15 PM
Storrs Campus video conferencing
Prof. Chiara Mingarelli, Department of Physics, University of Connecticut
Probing supermassive black hole mergers with pulsar timing
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in this band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers. -
Graduate Student Lukasz Kuna, Department of Physics, University of Connecticut, "Mesoscale Studies of Nanostructured Multi-Functional Materials", PhD Dissertation Defense10:00am
4/16
Graduate Student Lukasz Kuna, Department of Physics, University of Connecticut, "Mesoscale Studies of Nanostructured Multi-Functional Materials", PhD Dissertation Defense
Thursday, April 16th, 2020
10:00 AM - 12:00 PM
Storrs Campus Video meeting
Graduate Student Lukasz Kuna,
Department of Physics,
University of Connecticut
Mesoscale Studies of Nanostructured Multi-Functional Materials
In this dissertation, multiple studies centered around functional properties of materials for applications in devices and novel technologies are carried out utilizing a mesoscale modeling approach. The studies involve simulating the properties of dielectric nano/microstructures with coupled polar and elastic degrees of freedom and developing a greater understanding of their dependence on the structure size, morphology and applied external conditions. Of particular focus in this work are optical properties of electroactive materials including zero- and one-dimensional structures such as nanoparticles and nanowires, as well as mesoscopic functional properties of larger structures such as polycrystalline ceramics (with submicron grain sizes) and ferroelectric mesa structures. The first two research topics are focused on the band gap properties of 1-D semiconductors and modeling of ferroelectric mesa structures, each study serving as an important tool in progressing the understanding of these materials for functional applications. The final topic, comprising the larger portion of the work, presents a novel approach for studying transmission in nanocrystalline ceramics based upon wave-train theory, that is then utilized to predict light transmission in polycrystalline ceramics. In particular, simulations examining the optical properties modulation under different applied mechanical and electrical boundary conditions predict large changes to transmission, including switching from full transparency to opacity in some instances. The results presented in this dissertation highlight an extraordinary promise of functional nano- and microceramics for a wide range of advanced engineering applications. -
Prof. L. Levitov, Department of Physics, MIT, "Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids", Condensed Matter Physics Seminar9:00am
4/10
Prof. L. Levitov, Department of Physics, MIT, "Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids", Condensed Matter Physics Seminar
Friday, April 10th, 2020
09:00 AM - 10:00 AM
Storrs Campus online
Prof. L. Levitov, Department of Physics, MIT
Long-Lived Excitations, Directional Memory and Hydrodynamic Transport in Two-Dimensional Electron Fluids
It was found recently that 2D electron fluids can support collective excitations that are not subject to Landau's \(T^2\) dissipation [1,2,3]. This surprising behavior originates from the head-on carrier collisions, a process that dominates angular relaxation at not-too-high temperatures \(T \ll T_F\) due to the joint effect of Pauli blocking and kinematic constraints. As a result, a large family of exceptionally long-lived excitations emerges, associated with the odd-parity harmonics of momentum distribution. This leads to "tomographic" dynamics: fast 1D spatial diffusion along the unchanging velocity direction accompanied by a slow angular dynamics that gradually randomizes velocity orientation. The abnormally slow angular relaxation originates from correlated angular dynamics involving "lock-step'' angular displacements along the Fermi surface occurring in collinear two-particle collisions. The slow loss of directional memory is described as non-Brownian angular random walk, "superdiffusion" on the Fermi surface. The collective behavior with directional memory dominates at moderately long times, pushing the onset of conventional hydrodynamics to abnormally large timescales. The tomographic regime features an unusual hierarchy of time and length scales, resulting in scale-dependent transport coefficients. The scale dependence manifests itself in fractional-power current flow profiles and unusual conductance scaling vs. temperature and sample size. This exotic behavior can be directly probed by transport measurement techniques, as well as by momentum-resolved tunneling measurements.
1. P J Ledwith, H Guo, L Levitov, The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases,
Annals of Physics 411, 167913 (2019)
2. P J Ledwith, H Guo, A V Shytov, L Levitov,
Tomographic Dynamics and Scale-Dependent Viscosity in Two-Dimensional Electron Systems,
Phys Rev Lett 123, 116601 (2019)
3. P J Ledwith, H Guo, L Levitov, Angular Dynamics and Directional Memory in Two-Dimensional Electron Fluids,
2019
Zoom Meeting: https://kth-se.zoom.us/j/123036826