The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Spring 2022

Unless noted otherwise, Tuesday Colloquia are at 4:00 PM
Scheduling for additional seminars will vary.

For the Online colloquia, please join Zoom Meeting:
https://olemiss.zoom.us/j/91928227187
Meeting ID: 919 282 27187

Date/Place Speaker Title (and link to abstract)
Tue, Jan 18
Lewis 101
 
 
 
 
Tue, Jan 25
Lewis 101
Physics Graduate Students
Department of Physics and Astronomy
University of Mississippi
Xinyue Gong: Hall Effect for Acoustic Waves Carrying Angular Momentum
Guoqin Liu: Modeling and Simulations of Capillary-Gravity Wave Transmission Through a Surface Piercing Barrier
Tue, Feb 1
Lewis 101
M. Mahbub Alam
 
Daffodil International University, Dhaka, Bangladesh
Effects of Viscosity on Effective Dynamic Properties
Tue, Feb 8
Lewis 101
Suravinda Kospalage
Department of Physics and Astronomy
University of Mississippi
Study of the Decay B± → Ks0π±π0 at the Belle Experiment
Tue, Feb 15
Lewis 101
Dipangkar Dutta
Department of Physics and Astronomy
Mississippi State University
The Incredible Shrinking Proton and the Proton Radius Puzzle
Tue, Feb 22
Lewis 101
Katerina Chatziioannou
Division of Physics, Mathematics and Astronomy
California Institute of Technology
Constraining the Neutron Star Equation of State with Gravitational Wave Signals
Tue, Mar 1
Lewis 101
No colloquium
 
 
 
Tue, Mar 8
Lewis 101
No colloquium
 
 
 
Tue, Mar 15
Lewis 101
Spring Break
 
 
 
Tue, Mar 22
Lewis 101
Stefano Tognini
Nuclear Energy and Fuel Cycle Division
Oak Ridge National Laboratory
Celeritas: Bringing Exascale Computing to HEP Detector Simulation
Tue, Mar 29 Biswaranjan Behera
Department of Physics
Colorado State University
The Search for Sterile Neutrinos with the ICARUS Detector at Fermilab
Tue, Apr 5 Erika Hamden
Department of Astronomy and Steward Observatory
University of Arizona
Building Your Own Ultraviolet Telescope
Tue, Apr 12 Zhenhua Tian
Department of Aerospace Engineering
Mississippi State University
Leveraging Acoustics for Structural Health Monitoring and Noncontact Manipulation of Micro/Nano Objects
Tue, Apr 19 Prajwal Mohan Murthy
Department of Physics
University of Chicago
Search for the Neutron Electric Dipole Moment and "what next?"
Tues, Apr 26
Chu Ma
Department of Electrical and Computer Engineering
University of Wisconsin-Madison
Functional Materials/Devices and Signal Processing for Acoustic Sensing
Tue, May 3 Final Exam Week  

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Abstracts of Talks


Xinyue Gong
Department of Physics and Astronomy
University of Mississippi

Hall Effect for Acoustic Waves Carrying Angular Momentum

Acoustic waves with a twisted wave front also carry angular momentum in addition to linear momentum, in analogy to optical and quantum fields. The law of refraction states that the direction of refracted light rays is normally in the plane of incidence as they propagate across a sharp interface. Nevertheless, the refraction law is not enough to describe the angular momentum carried by refracted beams. Refracted light beams carrying angular momentum have been observed to undergo a shift in the direction that is transverse to the plane of incidence, a phenomenon that was termed as optical Hall effect. Here we pursue the first experimental observation of Hall effects for acoustic waves that carry angular momentum. Our experiment exploits the more recently developed acoustic metasurface to manipulate the wave refraction. A theoretical calculation of the wave fields is also conducted to compare with the experimental measurements. The talk will present physics related to the phenomenon, our experimental setup, and preliminary results.


Guoqin Liu
Department of Physics and Astronomy
University of Mississippi

Modeling and Simulations of Capillary-Gravity Wave Transmission Through a Surface Piercing Barrier

Capillary-gravity waves are waves traveling on a fluid interface that are influenced by both the effects of surface tension and gravity. Interactions of capillary-gravity waves with boundaries in contact with a solid and air play an essential role in both fluid physics and fluid control techniques. Motion of the contact line at the three phase boundary (solid, liquid, and air) can influence the wave dynamics such as the wave frequency, damping, refraction, and transmission. Here we develop fluid dynamics modeling and numerical simulations to investigate the transmission of capillary-gravity wavesthrough a surface piercing barrier under the effect of a pinned contact line. Our modeling is validated via a comparison with prior theory in ideal cases. We numerically reveal how the surface tension and contact lines affect the transmission in the realistic case for waves of different frequencies and barriers of different depths.


M. Mahbub Alam
 
Daffodil International University, Dhaka, Bangladesh
 

Effects of Viscosity on Effective Dynamic Properties

Recent theoretical and experimental findings demonstrate that as the particle concentration in a suspension increases, the effect of viscosity of the base fluid becomes more and more significant, thereby requiring to be taken into account when calculating effective properties of a suspension. Here, we employ a core-shell, self-consistent, effective medium model to derive analytical approximations for effective bulk-modulus and effective mass density for a suspension of solid elastic spheres. We incorporate the viscosity of the suspending fluid into the model through wave conversion phenomena, primarily between compressional and shear wave modes. The analytical approximations are explicit functions of particle volume fraction, dimensionless compressional and shear wavenumbers, and scattering coefficients of a single sphere. The dependence of effective properties on frequency, particle size, volume fraction, and viscosity are also investigated numerically.


Suravinda Kospalage
Department of Physics and Astronomy
University of Mississippi

Study of the Decay B± → Ks0π±π0 at the Belle Experiment

Belle is a particle physics experiment based at the KEK laboratory in Tsukuba Japan which ran from 1999 to 2010 and collected 1ab-1 of data. The Belle experiment is focused on studying the properties of particles called B mesons which are produced by accelerating and colliding electron and positron beams. These B mesons show the biggest differences between the properties of matter and anti-matter of any known particles. One of the main goals of the Belle experiments is to understand the differences between matter and anti-matter, specifically violations of charge-parity symmetry (CP violation) and how anti-matter vanished and we come to ive in a matter dominated universe.

This project explores the charmless B decay B± → Ks0π±π0 with the Belle full Monti Carlo (full MC) simulation and Belle data corresponding to 571fb-1 of luminosity and measure the decay's branching fraction (BF). Charmless transitions can proceed by a b → u transition via a tree level diagram or b → s or d transition via the so-called penguin diagram. Both decay types are highly suppressed compared to the b → c transition and we expect a small branching fraction, smaller than 10-5. The challenge in observing the B± → Ks0π±π0 decay is to suppress backgrounds from continuum events, which do not contain b quarks, and background from other B meson decays. Initial selections plus multi-variate analysis (MVA) machine learning/artificial intelligence technique called a boosted decision tree (BDT) used to reduce the backgrounds to the level to allow to clearly observe the decay and measure the BF.

Additionally the Dalitz plot (DP) technique to study the intermediate resonance contributions in this decay using the Laura++ software to generate and fit toy Monte Carlo (toy MC), full Monte Carlo simulated data, and, based on the techniques developed on these simulations, the experimental data to study the resonance sub-structure of this decay.


Dipangkar Dutta
Department of Physics and Astronomy
Mississippi State University

The Incredible Shrinking Proton and the Proton Radius Puzzle

For nearly half a century the charge radius of the proton had been obtained from measurements of the energy levels of the hydrogen atom or by scattering electrons from hydrogen atoms. Until recently the proton charge radius obtained from these two methods, agreed with one another within experimental uncertainties. In 2010 the proton charge radius was obtained for the first time by precisely measuring the energy levels of an exotic kind of hydrogen atom called muonic hydrogen. The charge radius of the proton obtained from muonic hydrogen was found to be significantly smaller than those obtained from regular hydrogen atoms. This was called the “proton charge radius puzzle” and led to a rush of experimental as well as theoretical efforts to understand whythe size of the proton appears to be different when measured in regular hydrogen vs. muonic hydrogen. Many physicists were excited by the possibility that the “puzzle” was an indication of a possible new force that acted differently on electrons and muons.

The Proton Charge Radius (PRad) experiment at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) was one such major new effort which used electron scattering from a regular hydrogen atom, but with several innovations that made it the highest precision electron scattering measurement. These innovative methods have allowed us to measure the size of the proton more precisely than it has been measured before using electron scattering. I will provide a brief review of the techniques used to measure the proton's size and introduce the “ proton radius puzzle”, and the world-wide effort to resolve this puzzle. I will discuss the PRad experiment, the new results from this experiment, the current status of the “puzzle” and future prospects.


Katerina Chatziioannou
Division of Physics, Mathematics and Astronomy
California Institute of Technology

Constraining the Neutron Star Equation of State with Gravitational Wave Signals

Detections of neutron stars in binaries through gravitational waves offer a novel way to probe the properties of extremely dense matter. In this talk I will describe the properties of the signals we have observed, what they have already taught us, and what we expect to learn in the future. I will also discuss how information from gravitational waves can be combined and compared against other astrophysical and terrestrial probes of neutron star matter to unveil to the properties of the most dense material objects that we know of.


Stefano Tognini
Nuclear Energy and Fuel Cycle Division
Oak Ridge National Laboratory

Celeritas: Bringing Exascale Computing to HEP Detector Simulation

Within the next decade experimental High Energy Physics (HEP) will (mostly) finish building its next generation of particle detectors. This includes upgrades to the Large Hadron Collider and its main experiments, and completing the Deep Underground Neutrino Experiment (DUNE). This new Era brings a myriad of challenges, many being on the computational front. As DOE consolidates its network of Leadership Computing Facilities (LCFs) with supercomputers capable of reaching Exaflops of processing power, it is fundamental to better integrate these LCFs with HEP computing workflows. In this talk I will provide an overview of computing in HEP and its many challenges, and present Celeritas, a novel GPU Monte Carlo particle transport code developed by researchers from ORNL, Fermilab, ANL, and BNL, that aims to close the gap between DOE's LCFs and HEP experiments.


Biswaranjan Behera
Department of Physics
Colorado State University

The Search for Sterile Neutrinos with the ICARUS Detector at Fermilab

The 476-ton active mass ICARUS T-600 liquid Argon Time Projection Chamber (LArTPC) was a pioneering development that became the template for neutrino and rare event detectors, including the massive next generation international Deep Underground Neutrino Experiment. It began operation in 2010 at the underground Gran Sasso National Laboratories and was transported to Fermilab in the US in 2017. To ameliorate the impact of shallow depth operation at Fermilab, the detector was enhanced with the addition of a new high granularity light detection system inside the LAr volume and an external cosmic ray tagging system. Currently in the final stages of commissioning, ICARUS is the largest LArTPC ever to operate in a neutrino beam. In this talk I will describe how ICARUS will resolve a long-standing neutrino anomaly that favors the existence of a new, non-interacting, "sterile" neutrino.


Erika Hamden
Department of Astronomy and Steward Observatory
University of Arizona

Building Your Own Ultraviolet Telescope

Why do galaxies look the way they do? How do galaxies interact with their environments? How does a star form? How does the environment around a new star impact the planets that form around it? These questions can all be answered by observations in the ultraviolet, a seriously neglected wavelength range. In this talk, I will discuss several space and sub-orbital UV telescopes that I am developing to answer the questions above, including FIREBall-2 (a balloon-borne UV spectrograph), Aspera (a NASA funded extreme UV SmallSat), and Hyperion (a FUV mission in development). I will also describe the importance of technology development in enabling these missions and the science they can achieve. Finally, I will argue that the best way to answer difficult science questions is to stop waiting for someone else to build your telescope.


Zhenhua Tian
Department of Aerospace Engineering
Mississippi State University

Leveraging Acoustics for Structural Health Monitoring and Noncontact Manipulation of Micro/Nano Objects

Acoustic waves carry both information and energy that allow them to inspect material defects as well as create invisible robotic hands (i.e., acoustic tweezers) capable of manipulating matter. This talk will cover my previous studies on leveraging acoustics for structural health monitoring (SHM) and noncontact manipulation of micro/nanoparticles. The first part of the talk is about SHM systems based on laser ultrasonics and ultrasonic arrays for rapid inspection of defects in aerospace structures, such as delamination in composites, disbonding in honeycomb sandwich panels, and corrosion in metal plates. The second part of my talk focuses on dynamic acoustic tweezers based on 10's MHz surface acoustic waves (SAWs). These SAW-based acoustic tweezers use a programmable array of interdigital transducers (IDTs) for the translation, patterning, and concentration of micro/nano objects. Their functions will be discussed with experimental examples, including (i) constructing diverse lattice-like patterns of micro/nanoparticles, (ii) manufacturing composites with patterned carbon nanotubes, and (iii) printing anisotropic tissues with aligned cells.


Prajwal Mohan Murthy
Department of Physics
University of Chicago

Search for the Neutron Electric Dipole Moment and "what next?"

Baryon asymmetry of the universe, i.e. the fact that much of the observed universe is made of matter as opposed to equal amounts of matter and anti-matter, demands violation of Charge-Parity (CP) symmetry. Yet, the amount of CP violation from the Standard Model of particle physics is insufficient to explain the baryon asymmetry of the universe. Observation of a non-zero permanent electric dipole moment (EDM) coupled to the spin of any sub-atomic particle, such as the neutron, is an indication of CP violation. Therefore, measuring the neutron EDM, is a key technique of getting a handle on the amount of CP violation. The neutron EDM from the standard model sources is so small that no experiment has thus far achieved the sensitivity required. Nonetheless, searches for the neutron EDM is an important method by which to test and constrain physics beyond the standard model. The neutron EDM has been measured since the 1940s and the sensitivity of the experiments has improved by over 8 orders of magnitude.

The most recent series of efforts were conducted at the Paul Scherrer Institute (PSI). This was a room temperature experiment employing the Ramsey technique of separated oscillating fields. These measurements used a 21 l storage chamber, in which ultracold neutrons were stored, and surrounded by 4 layers of mu-metal. Prior to 2006, the series of measurements at the Institut Laue-Langevin (ILL) culminated in the measurement of dn < 3 × 10-26 e.cm (90% C.L) [Phys. Rev. D 92, 092003 (2015)] over 5 years of data taking. The ILL apparatus was upgraded significantly with addition of: (i) 16 Cs-133 magnetometers to further characterize the magnetic field environment in the storage chamber, (ii) a new neutron detector system which could simultaneously count both the spin states of the neutron, and (iii) optimized coating inside the storage chamber to maximize the neutron density. The upgraded apparatus was moved to the Paul Scherrer Institute and independently achieved a measurement of dn < 1.8 × 10-26 e.cm (90% C.L) [Phys. Rev. Lett. 124, 081803 (2020)] in just 2 years of data taking. The PSI nEDM experiment has also been a source of rich physics program beyond the measurement of the nEDM. It has investigated neutron oscillation, provided input into neutron lifetime measurements, searched for axions, and tested Lorentz Invariance.

While the search for CPV EDM was first attempted in neutrons, searching for atomic EDM may be a more lucrative avenue, since multiple sources contribute to an atomic EDM, viz. nucleon EDM, nuclear Schiff moment, CP violating interactions between the electrons and the nuclei, and the nuclear MQM also contributes to the atomic EDM. Nuclear Schiff moment and nuclear MQM are significantly enhanced in quadrupole and octupole deformed nuclei. We will also discuss viable candidate isotopes which have maximally enhanced sensitivity to EDMs.


Chu Ma
Department of Electrical and Computer Engineering
University of Wisconsin-Madison

Functional Materials/Devices and Signal Processing for Acoustic Sensing

Acoustic wave propagates through mechanical vibration, with frequencies ranging from below 20Hz to above 20MHz. Each frequency range corresponds to important areas of applications. Particularly, ultrasound is one of the most important diagnosis and therapy methods, allowing non-invasive, non-radiative imaging with resolutions in sub-millimeter range as well as tumor treatment, drug delivery, and excitation of neurons. Besides biomedical field, acoustic sensors and acoustic signal processing technologies support the development of non-contact and non-destructive sensing and communication capabilities both on land and in water.

In this talk, I will present our work on developing functional materials/devices and signal processing technologies for acoustic sensing applications. First, I will talk about utilizing combination of functional materials and computational imaging methods for acoustic super-resolution imaging that breaks the diffraction limit and achieves subwavelength resolution. Second, I will talk about the monitoring of microwave/ultrasound ablation enabled by thermoacoustic signals generated during pulsed heating. Third, I will talk about a new type of acoustic wearable sensor that is formed by piezoelectric fibers sewed into a fabric sheet. The sensor operates as a sensitive audible microphone while retaining the traditional qualities of fabrics, such as machine washability and draping.