2021
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Tuesday, December 14, 2021 |
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Friday, December 10, 2021
Improving the Semi-classical Approximation of the Volume Eigenvalues and Eigenfunctions of Tetrahedral Grains of Space
Santanu Antu, '23 Hegeman 107 12:00 pm – 1:00 pm EST/GMT-5 Semiclassical theory is a powerful tool to analyze quantum phenomena even without invoking the full edged quantum mechanics. One of the most pivotal approximation schemes int he semiclassical theory is the WKB approximation (named after physicists Gregor Wentzel,Hendrik Anthony Kramers, and L eon Brillouin). The WKB approximation has been used to understand various quantum mechanical systems, including, but not limited to, infinite square well, harmonic oscillator, quartic oscillator etc. Even though most of the quantum mechanical problems mentioned here have been solved exactly, the WKB analysis provides a very intuitive insight to the inherently mysterious quantum theory. Our usage of WKB theory was devoted to understand a very central aspect of quantum gravity- the quantization of space. The eigenvalues of the tetrahedral grains of space using the rst order WKB approximation has already been studied in the literature of loop quantum gravity. In this project, we derived the eigenfunctions using WKB theory, and compared them with the exact wavefunctions. Aside from that, we also obtained a better approximation for the eigenvalues. Even though the previous first order approximations agree with the exact quantization nicely, there were cases where it lacked accuracy (as much as 16%). In our project for the summer, we tried to attain better approximation of the eigenvalues using higher order terms in the WKB approximation. Our approximation method is facilitated by a special differential equation, called the Picard-Fuchs differential equation. In our case, it is a third order differential equation with a constant solution. Since the differential equation that governs our system has only three independent solution (including the constant solution), it is apparent that the higher order action integrals can be represented as a combination of the lower order action integrals. The project demonstrates the underlying Picard-Fuchs equation for the system and a method of getting higher order approximation of the eigenvalues of the tetrahedral grains of space. |
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Friday, December 3, 2021 Hegeman 107 12:00 pm – 1:00 pm EST/GMT-5 Short wavelengths of light, from the X-ray to the UV, can be used to probe the abundance and phase (solid versus gas) of the most prevalent metals in the Universe. I will discuss two science frontiers: astromineralogy of the ISM with high resolution X-ray spectroscopy and short wavelength transmission spectroscopy of exoplanet atmospheres. The X-ray energy band is sensitive to absorption and emission by all abundant metals in the interstellar medium (ISM), both in gas and dust form, enabling us to answer key questions in dust grain growth and processing. X-ray photoabsorption features observed in high resolution spectra of Galactic X-ray binaries directly reveal the mineral composition of interstellar dust. I will describe the latest breakthroughs in this area and explain how XRISM, the next space based observatory to deploy an X-ray microcalorimeter, will contribute to the field. On the exoplanet frontier, the high energy environment in which planets evolve is believed to play an important role in the observed demographics of exoplanet populations. I will highlight the work being done in my research group, including work to detect NUV exoplanet transits with the Neil Gehrels Swift Observatory. |
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Friday, November 19, 2021 Hegeman 107 12:00 pm – 1:00 pm EST/GMT-5 Using archival documents and from conversations with former faculty and students, the college archivist will share physics stories from Professor Stryker's Recitation room to Zog 4. (And beyond.) |
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Friday, November 12, 2021 Hegeman 107 12:00 pm – 1:00 pm EST/GMT-5 The supermassive black hole at the Galactic center, Sagittarius A*, is the least luminous known supermassive black hole, but relics in its surroundings show that it has not always been so quiet. X-ray observations of the diffuse emission at the Galactic center performed over the last two decades have revealed an intense and highly variable nonthermal component, spatially correlated with dense molecular clouds present in the central three hundred parsecs. This reflection signal has been identified as echoes created by the past activity of Sagittarius A*. However, using these reflection features to reconstruct its precise history over the last centuries has been challenging. Through dedicated X-ray variability and spectral analyses, we are now able to derive an increasing number of constraints on two past outbursts from Sagittarius A* that occurred in the last centuries. However, what caused these events is still an open question. I will review how and what we have learned about Sagittarius A*'s past activity. |
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Friday, November 5, 2021 Hegeman 107 12:00 pm – 1:00 pm EDT/GMT-4 According to the standard model of physics, the neutron which is made up of quarks should have a finite electric dipole moment (edm). However, precision measurements of the neutron's edm place a vanishingly small upper bound on it. This is referred to as the strong CP problem. The axion is a new particle that was proposed to solve the strong CP problem. The possible mass range for the axion spans about 20 orders of magnitude. In certain circumstances, the axion can also explain dark matter. In my talk, I will describe a new experiment under development to look for the axion in the 10^-5 - 10^-2 eV mass range. This experiment, ARIADNE, will look for a spin-dependent force between an unpolarized source mass and a highly polarized ^3He gas mediated by the axion. The effect is equivalent to a fictitious magnetic field applied to the ^3He gas. In order to make this measurement, we need to be able to measure magnetic fields as small as 10^-21 T. This experiment requires bringing together multiple cutting-edge technologies into one system. I will describe the challenges in integrating these technologies towards achieving the required precision as well as our progress towards mitigating them. |
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Friday, October 29, 2021
Surabhi Sachdev, University of Milwaukee
Hegeman 107 12:00 pm – 1:00 pm EDT/GMT-4 We are in the era of gravitational-wave and multi-messenger astronomy, kick-started by the Advanced LIGO and Advanced Virgo detectors. The Advanced detectors concluded their third observing run (O3) in March 2020. The latest catalog of compact binary coalescences which analyzed data up until the first half of O3 contains 55 events consistent with binary black holes and binary neutron stars. In addition, two events consistent with neutron star black hole binaries were reported in the data from the second half of O3. I will provide a summary of the gravitational-wave data observations and describe what we can learn from these. I will conclude by discussing what we can expect from the upcoming observing runs. |
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Friday, October 22, 2021 Reem-Kayden Center 4:00 pm – 6:00 pm EDT/GMT-4 |
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Friday, October 22, 2021
Dani Schultz
Merck Pharmaceuticals Reem-Kayden Center Laszlo Z. Bito '60 Auditorium 12:10 pm – 1:10 pm EDT/GMT-4 Aspects of this session will highlight my journey from a small town in northern Wisconsin to the bustling east coast where leaning into discomfort has been critical in driving my career at Merck and the chemistry that I have pursued. Throughout my career, I have tapped into my ability to forge meaningful collaborations, internally and externally, to challenge the status quo and drive disruptive thinking – both in chemistry but also in improving STEM culture. I’ll briefly touch upon some recently completed academic-industrial research collaborations that aimed to empower early-career female professors and provide a platform to mentor and train female professors and students in pharmaceutical research. Throughout all of this, I have a passion for diversity, equity and inclusion and will share how I’ve navigated raising important, and at times difficult, topics and how to influence workplace culture. I’ve learned a lot through failed experiments along the way and I am looking forward to an active discussion with fellow changemakers! Dani Schultz received her PhD from the University of Michigan working with Professor John Wolfe and was an NIH postdoctoral fellow at the University of Wisconsin-Madison with Professor Tehshik Yoon. Since joining Merck in 2014, Dani has been a member of Process Chemistry and Enabling Technologies in Rahway, NJ and as of 2021 became the Director of the Discovery Process Chemistry group in Kenilworth, NJ. Throughout her time at Merck, Dani has been involved in the development of synthetic routes for drug candidates spanning HIV and oncology – forging meaningful collaborations, both internally and externally, to address the synthetic challenges that occur during pharmaceutical development. Most recently, she has served as co-host to the Pharm to Table podcast that aims to elevate the people and stories behind #MerckChemistry. |
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Friday, October 22, 2021 Hegeman 107 12:00 pm – 1:00 pm EDT/GMT-4 Dark matter is a mysterious substance that composes ~85% of the total mass of the Universe and is responsible for the formation of galaxies in the early Universe and for the motion of stars in our Milky Way Galaxy today. Evidence for the existence of dark matter comes from astrophysical observations of its gravitational effects across a range of time and distance scales. However, despite its ubiquity and abundance, dark matter is difficult to detect because it barely interacts with other particles. Understanding the particle nature of dark matter remains one of the largest open questions in particle and astrophysics. In this seminar, I will present diverse pieces of evidence for the existence of dark matter and discuss the current knowledge of its properties. I will then introduce the General AntiParticle Spectrometer (GAPS) Experiment, an upcoming NASA Antarctic balloon mission to detect cosmic particles as possible signatures of dark matter interactions in our Galaxy. I will highlight some of the detector development work at the heart of the GAPS mission, including contributions from undergraduate researchers. I will conclude by looking forward to the scientific results you can expect from GAPS over the next few years. |
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Friday, October 15, 2021 Hegeman 107 12:00 pm – 1:00 pm EDT/GMT-4 Black holes are perhaps the most mind-boggling object ever conceived by physicists. At the same time, they are real astrophysical objects created at the end of the life of massive stars. And astronomers can observe them - or rather their influence on their interaction with their environment. Some of the best objects to do so are X-ray binaries, systems that consist of a black hole and a normal star. As some of the stellar material is accreted onto the black hole, an accretion disk forms and X-ray emission is produced. In this talk, I will first discuss how observing this emission using space-based X-ray telescopes allows us to learn more about black holes and in particular measure their spin and then focus on a recent discovery of so-called returning radiation from black hole accretion disks. |
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Friday, October 8, 2021 Hegeman 107 12:00 pm – 1:00 pm EDT/GMT-4 This year's Nobel Prize in physics, awarded to Giorgio Parisi, Syukuro Manabe, and Klaus Hasselmann, was bestowed for finding order in what appear to be hopelessly complex systems. This general audience talk will explain how the laureates started from simple physical principles, braved a thicket of noise and intricate interactions, and emerged from the other side with new tools that deepen our understanding of systems ranging from the material to the biological, from machine learning to meteorology. Along the way they found answers to some scholarly questions and some with global climate implications. Pizza to be served after the talk! |
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Friday, September 3, 2021 The new semester has started and we would like to invite you to our traditional meet-and-greet Physics Phriday this Friday from noon to 1pm. We hope you will join us for some socializing, pizza and fun. It will be a chance for the new to get to meet with us and their fellow students, and the old to reunite. It is also a good opportunity to ask more about physics jobs and other program-related activities. |
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Thursday, May 20, 2021 Main Commencement Tent 5:30 pm – 7:00 pm EDT/GMT-4 Please see the abstract booklet below for full descriptions of students' research. Download: Senior Project Poster session booklet S21.pdf |
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Friday, April 23, 2021
Evan Telford, Columbia University
Online Event 12:00 pm – 1:00 pm EDT/GMT-4 The study of two-dimensional (2D) materials is one of the fastest growing fields in condensed matter physics. These materials promise to revolutionize nanotechnology due to the ability to easily isolate clean atomically-thin sheets of conducting material for use in atomic-scale circuits. Since the initial demonstration of the electric-field effect in devices fabricated from mechanically exfoliated graphene, the number of available 2D compounds that can be integrated into nanocircuits has grown exponentially to encompass diverse electronic properties such as semiconductors, superconductors, and magnets. A significant engineering challenge within the 2D community is the fabrication of devices from air-sensitive 2D crystals for electrical transport measurements. We have successfully addressed this challenge by developing a technique for embedding metal electrodes within atomically-thin insulating flakes used to simultaneously contact and preserve a wide array of air-sensitive 2D materials. Using this technique, we fabricated electrical transport devices from few-layer CrSBr, a new magnetic 2D semiconductor. We found CrSBr adopts a unique spin configuration in which individual layers ferromagnetically order internally, while adjacent layers couple antiferromagnetically. Through electrical transport measurements on CrSBr down to the single-layer limit, we observed strong coupling between magnetic order and electronic properties, leading to a resistivity that is reversibly controlled through external magnetic and electric fields. Zoom link for the event:https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 |
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Friday, April 16, 2021
Ke Fang, University of Wisconsin–Madison
Online Event 12:00 pm – 1:00 pm EDT/GMT-4 The study of compact objects such as black holes and neutron stars is an important component of modern astrophysics. Recent detections of astrophysical neutrinos, gamma rays, ultra-high-energy cosmic rays, and gravitational waves open up opportunities to study compact objects with multimessengers. In this talk, we first review the latest progress in astroparticle physics, including some surprising puzzles revealed by new observations. We demonstrate that the key to multimessenger astrophysics is to understand and establish the link between the messengers. We then illustrate how to reach this goal from both theoretical and observational perspectives. From the theoretical side, we show that high-energy particle propagation in the vicinity of compact objects may play an important role in connecting multiwavelength observation and source physics. From the observational side, we investigate analysis frameworks aiming to exploit data across multiple wavelengths and messengers.Zoom link:https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 |
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Friday, April 2, 2021
Andrea Richard, Michigan State University
Online Event 12:00 pm – 1:00 pm EDT/GMT-4 The fundamental challenges in nuclear science have been summarized in the 2015 Long Range Plan for Nuclear Science, which outlines four important questions, (1) How did visible matter come into being and how does it evolve? (2) How does subatomic matter organize itself and what phenomena emerge? (3) Are the fundamental interactions that are basic to the structure of matter fully understood? (4) How can the knowledge and technical progress provided by nuclear physics best be used to benefit society? The study of rare isotopes provides a means to investigate all of the questions posed in the Long Range Plan. The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University is a rare isotope facility that provides access to exotic, short-lived isotopes for experimental studies. Nuclear decays are simple probes that can be applied to rare isotopes at the limits of the production capabilities of the experimental facility and provide a variety of information including nuclear half-lives, decay branching ratios, and the energies of populated excited states. Beta-decay, in particular, plays an important role in nuclear science both for basic research and astrophysics due to its dominance across the nuclear landscape. However, many decay properties are not well known, especially for the more exotic isotopes. At the NSCL, we have developed a program to ascertain b-decay information, and in some cases neutron-capture cross sections, for nuclei involved in astrophysical processes. In this presentation, I will discuss b-decay measurements performed at the NSCL and their importance for basic nuclear science, nuclear astrophysics, and applications. I will also discuss the future Facility for Rare Isotope Beams (FRIB) and how it will provide a wealth of additional nuclei for study and enable experimental programs that are not feasible today. Join Zoom Meeting here: https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 |
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Friday, March 26, 2021
Haocun Yu, MIT
Online Event 12:00 pm – 1:00 pm EDT/GMT-4 The Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves for the first time in 2015. Since then dozens more events have been confirmed by the third observing run (O3). To detect these spacetime ripples requires the precision of the interferometric GW detectors to reach sub-attometer level, and we are always pursuing higher sensitivities. I will describe the main quantum technologies -- squeezing-- that make such precision possible and enable present and future discoveries. This talk will also give a clue to a more fundamental question: when using light as a probe to measure the position of a particle, what is the limit to the precision? Join the event either in-person at the Brody lab or via Zoom here: https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 |
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Friday, March 5, 2021
Colette Salyk, Vassar College
Online Event 12:00 pm – 1:00 pm EST/GMT-5 In this talk, I’ll present to you the standard fairy tale story for how planets form. Then, I’ll tell you (at least some of the reasons) why this story is incomplete and why it’s essential to make real measurements of planet formation processes. I’ll describe how my favorite technique, molecular spectroscopy, can be used to make ground-truth measurements of where, how, and under what conditions, planets form. I’ll also tell you about the soon-to-be-launched James Webb Space Telescope, and how this revolutionary telescope is going to radically improve our ability to understand the chemistry of planet formation.Zoom link:Join Zoom Meeting here: https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 One tap mobile +16465588656,,6121711443# US (New York) +13126266799,,6121711443# US (Chicago) Dial by your location +1 646 558 8656 US (New York) +1 312 626 6799 US (Chicago) +1 301 715 8592 US (Germantown) +1 253 215 8782 US (Tacoma) +1 346 248 7799 US (Houston) +1 669 900 9128 US (San Jose) Meeting ID: 612 171 1443 Find your local number: https://bard.zoom.us/u/acLMdOIdZE |
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Friday, February 19, 2021
Melissa Eblen-Zayas, Carleton College
Online Event 12:00 pm – 1:00 pm EST/GMT-5 Condensed matter physicists begin by developing simple models that capture the key properties of materials, but correlated electron materials are a class of materials where our simple models break down, giving rise to unusual electronic or magnetic properties. In this talk, I will share our research on one correlated electron material, EuO1-x, which is of interest for its possible spintronics applications. Because the transport and magnetic properties of EuO1-x are similar to another correlated electron material, the perovskite manganites, and phase inhomogeneity is important for describing the properties of the manganites, an interesting question is whether phase inhomogeneity is also relevant for describing EuO1-x. I will explore what phase inhomogeneity is, the evidence for phase inhomogeneity in the manganites, and our current understanding of the nature of phase inhomogeneity in EuO1-x, and I will share a bit about my journey as a physicist. https://bard.zoom.us/j/6121711443?pwd=d2k5NnNvWncwSEhNY1ovTTdUSHY1Zz09 Meeting ID: 612 171 1443 Passcode: 431280 |