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Events on Friday, April 29th, 2022

Theory Seminar (High Energy/Cosmology)
A chiral SU(5) theory with three generations
Time: 1:00 pm
Place: Chamberlin 5280
Speaker: Daniel Stolarski, Carleton University
Abstract: I will present a study of an interesting strongly coupled chiral quantum field theory. This theory has the same particle content as the simplest grand unified theory of the Standard Model. I will employ tools such as 't Hooft anomaly matching and softly broken supersymmetry to analyze the non-perturbative dynamics of the theory. I will also speculate on the more general lessons of my analysis.
Host: George Wojcik
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Thesis Defense
Intensity Mapping: Science and Instrumentation Across the Electromagnetic Spectrum
Time: 2:00 pm
Place: B343 Sterling or join online:
Speaker: Trevor Oxholm, Physics PhD Graduate Student
Abstract: Line intensity mapping is a growing technique for obtaining tomographic maps of the universe. Line intensity maps feature the integrated emission of a target spectral line from all galaxies within the field of view, making it an unbiased tracer of galaxy emission and a strong tool for galaxy evolution studies. Furthermore, line intensity mapping surveys may probe unprecedented volumes of the universe with modest time requirements, allowing for leading sensitivities of cosmological parameters. In this thesis, I describe modeling efforts for measurements of the intensity mapping signal and for instrumentation developed for the Experiment for Cryogenic Large- aperture Intensity Mapping (EXCLAIM!). EXCLAIM is a pathfinding balloon-borne intensity mapping instrument aiming to map ionized carbon ([CII]) and carbon monoxide (CO) at redshifts 2.5 < z < 3.5 and z < 0.64, respectively. I characterize the target observables in the survey and describe methods for forecasting the performance of the instrument. I apply these forecasting tools to the EXCLAIM survey and to a hypothetical space-based survey, which may be free from the limitations of cosmic variance. The EXCLAIM detectors and optical systems are also described in detail, and with a dual focus on system-level requirements. EXCLAIM features nascent superconducting spectrometer and detector technologies, which must be carefully characterized and modeled before the flight. I describe an operational procedure that may be used to optimize the detectors for an evolving signal, providing a critical advantage for EXCLAIM’s detectors over competing technologies. Finally, the optical system is modeled and shown to comply with system-level mission goals.
Host: Peter Timbie
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Physics Department Colloquium
Structural Dynamics in Biology using LCLS
Time: 3:30 pm
Place: 2103 Chamberlin Hall
Speaker: Mark Hunter, SLAC
Abstract: The resolution revolution of cryo-EM for experimental structure determination of biomacromolecules combined with the breakthrough results of AlphaFold and its derivatives for structure prediction of biomacromolecules have ushered in a new era in structural biology. This poses the question of what is the place for x-ray crystallography and x-ray Free Electron Lasers (xFELs) such as the Linac Coherent Light Source (LCLS) in structural biology moving forward? We believe that one compelling area of research using LCLS is studying the structural dynamics of biomacromolecules. LCLS and other xFELs offer very high temporal resolution combined with atomic spatial resolution while eliminating the ill effects of conventional radiation damage. This unique combination will facilitate the study of both triggered and stochastic biological dynamics. For example, the spatiotemporal resolving power of LCLS can be used to study the initial photophysics and photochemistry in light-sensitive proteins as well as short time points in an enzymatic reaction between a biomacromolecule and substrate. The structural methods can also be combined with powerful complimentary techniques, such as x-ray absorption and emission spectroscopies, to understand the structure and chemical environment of biomacromolecules. The presentation will cover the unique properties of LCLS and the upcoming upgrades to LCLS-II and LCLS-II-HE and how we can use a variety of additional technologies and methodologies to access a myriad of biologically relevant time scales.
Host: Uwe Bergmann
Presentation: Structural Dynamics in Biology using LCLS.docx
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