Events List for the Academic Year
Event Time:
Tuesday, September 8, 2020 | 5:45 pm - 6:30 pm
Event Location:
Canvas (online)
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2020-09-08T17:45:00
2020-09-08T18:30:00
PHAS Imagine Day
Event Information:
The department will be hosting an Imagine Day session for undergraduate students. PHAS academic advisors will introduce PHAS undergrad programs and share tips for planning your academic schedule and seeking job/research opportunities. PHAS alumni will share experiences from student clubs. The event will end with a live Q&A session with PHAS advisors.
Enroll now at https://canvas.ubc.ca/enroll/WK9DL9. Course materials will be available online for a month, after which content will be migrated to a PHAS webpage.
Event Location:
Canvas (online)
Event Time:
Monday, August 31, 2020 | 3:00 pm - 4:00 pm
Event Location:
Connect via zoom
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2020-08-31T15:00:00
2020-08-31T16:00:00
Revealing Structure in the Milky Way with Galactic HII Regions
Event Information:
The present-day structure of the Milky Way is a constraint on theories
of Galactic formation and evolution. HII regions, the zones of ionized
gas surrounding recently formed high-mass stars, are common tracers of structure in both the Milky Way and other galaxies. Over the past 10
years, we have more than doubled the number of known Galactic HII
regions by searching for radio recombination line emission toward
infrared-identified HII region candidates. I will discuss (1) our
latest project, the Southern HII Region Discovery Survey, (2) how we
can use our observations to derive the physical properties and
distances of the nebulae, and (3) what we are learning about the
morphological, kinematic, and chemical structure of the Milky Way with
a complete census of Galactic HII regions.
Event Location:
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Event Time:
Thursday, August 27, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-08-27T16:00:00
2020-08-27T17:00:00
A Journey from Tenure and a Life in Academia to Policy & Science Management at NASA HQ
Event Information:
Dr. Sheth will describe the current landscape of NASA astrophysics and the career path / life of a NASA Program Scientist. Dr. Sheth has worked in both the Astrophysics and Earth Science Divisions in NASA's Science Mission Directorate. He has a wide and diverse portfolio that includes operating and developing missions, the NASA Hubble fellowship program and science and technology research in the Cosmic Origins program. Previous to his civil service role at NASA HQ , Dr. Sheth had a complete academic career in which he studied the assembly and evolution of galaxy disks. He will compare and contrast the advantages and disadvantages of the two related but distinct and rewarding careers.
Event Location:
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Event Time:
Thursday, August 27, 2020 | 9:30 am - 11:30 am
Event Location:
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2020-08-27T09:30:00
2020-08-27T11:30:00
“Nuclide production and imaging applications of 225Ac for targeted alpha therapy”
Event Information:
Departmental Doctoral Oral Examination
Thesis Abstract (click here)
Event Location:
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Event Time:
Monday, August 24, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-08-24T15:00:00
2020-08-24T16:00:00
Precision Cosmology with the Atacama Cosmology Telescope
Event Information:
Observations of the cosmic microwave background (CMB) are foundational for the standard model of cosmology. Improved measurements of the CMB temperature anisotropy and polarization will further inform us about the history of the universe and its contents. The Atacama Cosmology Telescope (ACT) is mapping close to half the sky with arcminute resolution in multiple microwave bands. I will describe the recent cosmological results from ACT including the CMB angular power spectra and cosmological parameters.
Event Location:
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Event Time:
Thursday, August 20, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-08-20T16:00:00
2020-08-27T17:00:00
Show and Tell: reprise
Event Information:
Join us to find out what some people in Physics & Astronomy have been doing over the summer. We'll specifically hear updates from several earlier presenters, so we can find out what progress has been made on a wide range (a very wide range!) of projects. These brief talks should be accessible to everyone connected with our Department, and you don't need to have attended the earlier events to get something out of this.
Ryley Hill "How to enjoy a vacation during lockdown
Deborah Good "Costume Engineering: recreating 18th century women's fashion"
Berend Zwartsenberg "Covid and the Art of Motorcycle Maintentance"
Teagan Phillips "Intelligent Speech as an early podcaster"
Perrin Waldock "Homemade Home Automation"
Jess McIver "What I've learned since the Strike for Black Lives"
Douglas Scott "Laneways of Vancouver"
Event Location:
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Event Time:
Monday, August 17, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-08-17T15:00:00
2020-08-17T16:00:00
Site-testing results from Dome A, Antarctica
Event Information:
Dome A, the highest point of Antarctic plateau, has long been considered as a promising site for astronomy. Since it was first reached in 2005, the site-testing campaigns were initiated. The previous results prove that Dome A has dark and clear sky, the coldest air temperature (i.e., low thermal IR background), low wind speed and very low precipitable water vapour (i.e., high atmospheric transmission for terahertz and far-infrared astronomy). Moreover, the latest seeing measurements show that, at a height of just 8 m, the free-atmosphere seeing was achieved for 31% of the time, with a median value of 0.31 arcsec and a best value of 0.13 arcsec. And the fraction will be increased to one half at a height of 14 m. Compared with seeing values around 0.6 - 0.8 arcsec in Hawaii and Chile, the superb seeing at Dome A will result in both higher angular resolution and deeper limiting magnitude. According to these advantages, Dome A is arguably the best site on Earth for ground-based optical, infrared, and terahertz astronomy.
Event Location:
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Event Time:
Thursday, August 13, 2020 | 4:00 pm - 5:00 pm
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2020-08-13T16:00:00
2020-08-13T17:00:00
Exploring the Ultrahigh-Energy Universe with ANITA
Event Information:
The ANtarctic Impulsive Transient Antenna (ANITA) experiment is a balloon-borne radio telescope that, unlike most telescopes, points down in order to try to capture the impulsive Askaryan radio emission from energetic (>1 EeV) neutrinos interacting in the Antarctic ice sheet. Neutrinos at these energies have not yet been detected, but can be produced in interactions of cosmic rays with the cosmic microwave background or directly in astrophysical sources. ANITA is also sensitive to radio signals from extensive air showers, which are usually initiated by cosmic rays but could also potentially be produced by energetic tau neutrinos or exotic particles.
After four flights, ANITA sets the world's most stringent limits on ultrahigh energy neutrino flux above 30 EeV and additionally has detected dozens of extensive air shower candidates. Several of the observed events appear consistent with upward-going air showers, which currently lack a clear explanation. The Payload for Ultrahigh Energy Observations (PUEO) is the planned successor to the ANITA program, which will include significant sensitivity improvements.
Event Location:
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Event Time:
Monday, August 10, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-08-10T15:00:00
2020-08-10T16:00:00
Collision probabilities in the Edgeworth-Kuiper belt
Event Information:
The Edgeworth-Kuiper belt (EKB) is a torus-shaped agglomeration of small icy bodies, just beyond the orbit of Neptune. Due to their distant location, these objects are believed to be relatively pristine and may hold the key to understanding the formation of the Solar System. Until recently, EKB objects (EKBOs) were poorly characterized, primarily due to their large heliocentric distances. However, with the deployment of large dedicated EKBO surveys, such as the Deep Ecliptic Survey (DES), the Canada-France-Ecliptic-Plane-Survey (CFEPS) and the Outer Solar System Origin Survey (OSSOS), we have been able to obtain a detailed picture of the size and orbital distribution of these trans-Neptunian Objects (TNOs).
On 1st January, 2019 the NASA New Horizons spacecraft made a revolutionary close encounter with the cold classical Kuiper belt object 2013 MU69 – now named Arrokoth. The Student Dust Counter (SDC), aboard New Horizons, has almost constantly measured the dust spatial density throughout its journey to Arrokoth. While interplanetary dust in the inner Solar System is associated with Jupiter-family comets, dust beyond the orbit of Neptune has been linked to collisions between EKB objects. Dust density measurements, coupled with current EKB orbital models, could aid our understanding of the collisional history of these TNOs.
In this talk I will be presenting how we implement the OSSOS dynamical (orbital) model of the EKB and calculate the collisional probabilities between different EKBO dynamical populations. I will also be discussing how these results compare to crater number density observation on both the Pluto-Charon system and Arrokoth. The crater density measurements on these objects serve as a direct proxy for the collisional evolution of the Edgeworth-Kuiper belt.
Event Location:
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Event Time:
Thursday, August 6, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-08-06T16:00:00
2020-08-06T17:00:00
Space Exploration and Applied Physics
Event Information:
The Johns Hopkins University Applied Physics Laboratory is the largest University Affiliated Research Center in the USA. A core part of the Lab's mission is to provide critical contributions to some of the biggest challenges facing space exploration, through development of innovative technologies, engineering, and space science missions and instruments. In this presentation, I will first give a brief summary of APL's history in space science and relation to the broader US space enterprise, and then focus on some of the active projects at APL to explore our Sun, Ocean Worlds in the Solar System, and the heliosphere. I will also describe APL's latest efforts to build the first Planetary Defense mission, DART (the Double Asteroid Redirection Test).
Event Location:
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Event Time:
Thursday, July 30, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-07-30T16:00:00
2020-07-30T17:00:00
Comet NEOWISE show and tell!
Event Information:
Given the recent interest in Comet NEOWISE, this week we'll have an informal discussion about this naked-eye astronomical phenomenon and about comets in general. We'll start with a few members of our Department sharing the images of this object that they took themselves. Then our own Brett Gladman will give a short popular-level introduction on comets in general and some specific information about comet NEOWISE. We'll finish with plenty of time time for questions.
Event Location:
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Event Time:
Tuesday, July 28, 2020 | 9:00 am - 11:00 am
Event Location:
Virtual Defence
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2020-07-28T09:00:00
2020-07-28T11:00:00
"Leveraging the Light-Matter Interaction in Angle-Resolved Photoemission Spectroscopy”
Event Information:
PhD Final Oral Examination
Abstract:
The light-matter interaction is central to the photoemission process, with an ultraviolet photon providing the necessary impulse required to eject those electrons which we collect in an effort to understand the electronic structure of matter. As such, the selection rules associated with this interaction impose strict constraints on those electronic orbits to which the technique is sensitive. Photoemission-based techniques then present an opportunity to access information beyond spectroscopic characterization of a material’s level structure; an orbital description of the underlying wavefunctions is viable under consideration of the photoemission mechanism. We present here a numerical scheme within which such information about the photoemission experiment can be garnered, with specific application to several experiments on candidate materials. In particular, this methodology allows for new insights in the problem of the Fe-based superconductors. These materials are an ideal platform to apply this methodology. The low energy electronic structure is characterized by a large number of closely spaced, moderately correlated states. Their phenomenology is dictated by a delicate balance of several interactions with similar energy scales, the competition and cooperation amongst which pose a considerable challenge for both theory and experiment. The kinetic Hamiltonian, in addition to interactions involving Coulomb and Hund’s coupling, as well as nematic order and spin-orbit coupling are all closely related to the orbital structure of the electronic states. The unique sensitivity to both spin and orbital degrees of freedom which photoemission provides therefore allow for a comprehensive exploration of such energy scales in these compounds. Taking advantage of this sensitivity, we have mapped the momentum and energy dependence of spin-orbit entanglement in candidate materials FeSe and LiFeAs.
Despite the remarkable surface sensitivity which limits access to the crystal bulk in photoemission, there is a strong inclination to assert a correspondence between the bulk electronic structure, and that measured experimentally. Such a connection is by no means guaranteed, and is frequently the cause of misinterpretation. We explore the surface issue in detail, and discover an interference mechanism which provides justification for the unanticipated success of valenceband photoemission in quasi two-dimensional materials. The surface issue is of specific relevance to the Fe-superconductors, where certain orbitals exhibit significant dispersion perpendicular to the surface. We examine the canonical Fesuperconductor LiFeAs, wherein a confluence of three-dimensional dispersion, spin-orbit coupling, and surface states have conspired to preclude identification of the low-energy electronic structure. We combine detailed photon-energy dependent measurements with results from a slab-projected model to unambiguously identify the three-dimensional Fermi surface of this material.
Event Location:
Virtual Defence
Event Time:
Monday, July 27, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-07-27T15:00:00
2020-07-27T16:00:00
Chemistry and dynamics of newly discovered metal-poor stars
Event Information:
The analysis of Gaia DR2 data has revealed previously unknown accretion events of dwarf galaxies through detailed chemo-dynamical analyses of stars in the Milky Way (i.e., Gaia-Enceladus, Helmi et al. 2018; Gaia-Sausage, Belokurov et al. 2018; Gaia-Sausage, Myeong et al. 2019), and the unexpected result that many very metal-poor stars have nearly circular planar orbits (Sestito et al. 2019). These results show that very metal-poor stars are invaluable in mapping early and/or pristine accretion events, but they are hard to find without dedicated efforts. I will present recent results from a high-resolution spectroscopic analysis of 115 candidate metal-poor stars selected from the narrowband Pristine photometric survey (Starkenburg et al. 2017), and 30 metal-poor stars selected from the Pristine medium-resolution spectroscopy survey at the INT (Aguado et al. 2019, Youakim et al. 2017). These stars have been analysed with high-resolution spectroscopy from the Gemini GRACES and CFHT ESPaDOnS spectrographs (Venn et al. 2020; Kielty et al. 2020). We have discovered ~30 new bright (V < 16) stars with [Fe/H]< -2.5 and ~30 with [Fe/H]< -3.0, and our chemo-dynamical analyses based on SDSS and Gaia DR2 photometry, Gaia DR2 parallaxes and proper motions, and MESA/MIST stellar isochrones, has shown that most of these stars show chemical abundance patterns that are similar to the normal metal-poor stars in the Galactic halo. However, in addition, three new r-process rich stars have been found, and several stars with chemical peculiarities typically seen in stars in dwarf galaxies. Additionally, some stars show unusual kinematics for their chemistries, including planar orbits, unbound orbits, and highly elliptical orbits that plunge deeply into the Galactic bulge; also, eight stars that have orbital energies and actions consistent with the Gaia-Enceladus accretion event. In future, the combination of Gaia DR3 and the forthcoming spectroscopic surveys (WEAVE, 4MOST, PFS, and possibly MSE) will reveal chemo-dynamical structures throughout the MW that are currently only hinted at, and details of the nucleosynthetic events in Local Group dwarf galaxies, including some that have only been discovered in the past year.
Event Location:
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Event Time:
Thursday, July 23, 2020 | 4:00 pm - 5:00 pm
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2020-07-23T16:00:00
2020-07-23T17:00:00
The Future of Food in an Uncertain World
Event Information:
As an "accidental" food theorist, with both a science and social science background, I sometimes find myself struggling to understand a paradigmatic split within agricultural thought. On one side, technological advance has allowed us to cheaply and easily feed more people than ever before, but at a cost. The industrial food system is vulnerable, due to its reliance on cheap labour and its long supply chains. On the other side of the coin there are people calling for a more local, community-based food system, but it isn't clear how such a system would provide food year round, and how it would meet the demand of billions of consumers. And though more environmentally benign, so called "alternative" agriculture also struggles to sustainably source labour inputs. In this talk I discuss how agricultural technologies can be used to draw the best from both of these systems, but I also highlight that building a resilient agricultural system is also a social science problem; the public has a strongly held sense of what is "natural" and "green". Solving for the future of food is currently top of mind as we struggle with COVID-19 and as climate change looms over the horizon. I will close with some thoughts on our local agricultural industry, gleaned from my time on the Premier's Food Security Task Force.
Event Location:
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Event Time:
Monday, July 20, 2020 | 3:00 pm - 4:00 pm
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2020-07-20T15:00:00
2020-07-20T16:00:00
The origin of the most massive high redshift quasars
Event Information:
The discovery of billion solar mass quasars at redshifts of 6–7 challenges our understanding of the early Universe; how did such massive objects form in the first billion years? Observational constraints and numerical simulations increasingly favour the "direct collapse" scenario. In this case, an atomically-cooled halo of primordial composition accretes rapidly onto a single protostellar core, ultimately collapsing through the Chandrasekhar-Feynman instability to produce a supermassive (~100,000 solar mass) "seed" black hole. In this talk, I will present a systematic study of the lives and deaths of these objects, including post-Newtonian corrections to gravity and a detailed treatment of nuclear burning processes using an adaptive network. We find a simple relation between the infall rate and the final mass at collapse, rule out the existence of rapidly-rotating supermassive stars, and delineate the regimes for which objects either undergo "truly direct" collapse or survive to long-lived nuclear-burning under differing formation scenarios. I will also discuss the possibility of early chemical enrichment from these objects, observational prospects in the era of the JWST, and briefly summarize other future directions.
Event Location:
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Event Time:
Thursday, July 16, 2020 | 4:00 pm - 5:00 pm
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2020-07-16T16:00:00
2020-07-16T17:00:00
225-Actinium production at TRIUMF: combining physics, engineering, and chemistry for medicine
Event Information:
225Ac is an alpha-emitting radionuclide that has shown remarkable potential for use in targeted alpha therapy of late stage metastatic diseases, most notably prostate cancer. However, 225Ac-radiopharmaceutical development remains limited by the insufficient availability of the radionuclide, despite multiple efforts to increase 225Ac supply via alternative methods that avoid the use of nuclear weapons material. Accelerator-based methods are a potential alternative, with TRIUMF’s 500-MeV cyclotron uniquely positioned to produce substantial quantities of 225Ac via thorium irradiation that do not contain undesirable 227Ac impurities. In this talk I will discuss TRIUMF’s ongoing efforts to produce 225Ac, with a focus on the current state of the technology and the physical science foundation behind it. This foundation combines topics from multiple disciplines, but will be presented from the perspective of a physicist (who by accident now does a lot of chemistry). Topics include the design and modelling of thorium proton-targets, nuclear reaction cross-section measurements, high-energy particle transport simulations, chemical purification methods, and analytical techniques for determining product quality.
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Event Time:
Tuesday, July 14, 2020 | 12:11 am - 12:12 pm
Event Location:
Remote Talk
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2020-07-14T00:11:00
2020-07-14T12:12:00
The XENON1T excess: axions, background, or fluke?
Event Information:
XENON1T, the world's most sensitive dark matter detector, found a ~3.5 sigma excess of low energy (2-5 keV) electronic recoil events. This could be a first hint of axions produced in the sun, a nonzero neutrino magnetic moment, or absorption of bosonic dark matter. However, more mundane explanations remain possible, most importantly a trace of tritium contaminating the detector. I will summarize the result and discuss the evidence in favor of these different interpretations.
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522 666 677
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Event Location:
Remote Talk
Event Time:
Monday, July 13, 2020 | 3:00 pm - 4:00 pm
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2020-07-13T15:00:00
2020-07-13T16:00:00
Wayfinding Under Blackfoot Skies
Event Information:
Wayfinding Under Blackfoot Skies is a new project at the Rothney Astrophysical Observatory. This project involves the development of scientific based programs that investigate and explore Indigenous methods of celestial observation and the practical articulation of navigating by the stars. The core themes for the Wayfinding under Blackfoot Skies programs are a joining of Indigenous and Western science ideologies. I will talk about my research and how the observatory is working towards blending traditional knowledge into our programming and exhibits. Our new exhibit space is titled Convergence: Where the people of the land reach the sky.
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Event Time:
Thursday, July 9, 2020 | 4:00 pm - 5:00 pm
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2020-07-09T16:00:00
2020-07-09T17:00:00
Another Show and Tell
Event Information:
Join us for this set of short presentations:
Carl Michal "NMR at home: how hair conditioner is just like brains"
Alex Weber "Slacklining and highlining"
Robert Beda "Physics Mountain: 5 Lessons from Celeste"
Paul Ripoche "Why I started making bread before the pandemic"
Alexandra Qi "Recreating historical vehicles in miniature"
Bretta Russell-Schulz "Crochet: A beginner's guide for scientists"
Guy Leckenby "Defying gravity? The physics of the skateboard ollie"
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Event Time:
Monday, July 6, 2020 | 3:00 pm - 4:00 pm
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2020-07-06T15:00:00
2020-07-06T16:00:00
The Far-Infrared Universe
Event Information:
This talk will be an overview of science goals and technology drivers for studying the far-infrared sky.
Dr. Locke Spencer completed a BSc in Engineering Physics from UA in 2003, and then MSc and PhD degrees at University of Lethbridge in 2005, 2009, respectively, working primarily with the European Space Agency (ESA) Fourier Transform Spectrometer on Herschel/SPIRE. He completed a post-doctoral fellowship at Cardiff University School of Physics and Astronomy from 2009-2013 working primarily with the ESA Planck High Frequency Instrument (HFI). He returned to Canada in 2013 for a Canada Research Chair (Teir II) in Experimental Astrophysics.
Event Location:
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