Events

Mon, April 03 4:00pm
Duane Physics Room G125
Nuclear/Particle Physics Seminar
Supersymmetry: Aspirations and Prospects

Xerxes Tata,
University of Hawaii

Abstract/Details

The hypothesis of weak scale supersymmetry ameliorates the gauge hierarchy problem, yields gauge couplings consistent with grand unification, and when augmented by R-parity conservation, provides natural candidates for the observed dark matter (DM). However, experiments at the LHC have not turned up any direct evidence for the existence of superpartners, seemingly in conflict with early expectations that suggested that superymmetry would be revealed even at LEP2 or the Tevatron. We critically re-evaluate the arguments that led to these expectations and conclude that phenomenologically viable SUSY spectra with no worse that a few percent fine-tuning are perfectly possible. While no top-down model that lead to such spectra has as yet emerged, we show that it is nontheless possible to abstract many phenomenological implications of natural supersymmetry. We discuss prospects for SUSY discovery at the (high-luminosity) LHC, and argue that experiments at the proposed high energy LHC operating at 33 TeV would allow a definitive search for natural SUSY. We will also mention the complementary role of experiments at an electron-positron linear collider with a centre-of-mass energy of 600 GeV for elucidating the nature of a SUSY discovery in this framework.
Mon, April 03 4:00pm
JILA Auditorium
Astrophysical & Planetary Sciences Seminar
Hearing the Stars: New Insights into Stellar Interiors from Asteroseismology

Lars Bildsten,
University of California, Santa Barbara

Abstract/Details

Long-term and sensitive space-based photometry from the Kepler and CoRoT satellites has allowed us to finally 'hear' the stars. These remarkable data have yielded accurate measurements of masses, radii and distances for more than 30,000 stars across the Milky Way. More profoundly, these observations are revealing the interior conditions of the star, clearly differentiating those that are undergoing helium burning in their cores to those that are only burning hydrogen in a shell. Moreover, interior rotation rates for hundreds of post-main sequence stars have now been measured, probing the uncertain physics of angular momentum transport that is important to the progenitors of core collapse supernova. Most recently, the prevalence of red giants with very low dipolar oscillation amplitudes appears to be a consequence of strong magnetic fields deep in the helium cores of these red giants.  
Wed, April 05 3:30pm
JSCBB Butcher Auditorium
Biochemistry Seminar
TBA

Todd Yeates,
University of California Los Angeles
Wed, April 05 4:00pm
Duane Physics Room G1B20
Physics Department Colloquium
Thermoelectrics and Thermoelectric Materials

David Singh,
University of Missouri

Abstract/Details

Thermoelectric devices are used for the conversion of thermal and electrical energy. They offer a number of advantages over competing technologies including scalability to small sizes and temperature differences, simple reliable designs and often low cost. However, these devices have not seen wide application in energy applications due to their limited conversion efficiency. This is a consequence of the limited performance of current thermoelectric materials, which can be characterized by a dimensionless figure of merit, ZT=σS2T/κ. There is no known fundamental limit on ZT. However, the combination of transport parameters entering ZT is a combination that does not occur in ordinary materials. This talk presents an overview of ZT and discusses strategies for optimizing ZT as well as recent results that point to ways of identifying new high ZT compositions. An important finding is that electronic structure plays a remarkably subtle role in thermoelectric performance that can however be simply visualized in terms of iso-energy surfaces. Finally, a connection is drawn between topological insulators and high ZT thermoelectrics, explaining the overlap between these two interesting materials classes. Characteristics that can be used to identify new thermoelectric compositions are presented and discussed.
Fri, April 07 9:30am
Duane Physics Room G126
CTQM Seminar
Upper bounds on the one-way and two-way distillable entanglement from suitable convex decompositions

Felix Leditzky,
University of Colorado
Fri, April 07 12:00pm
JILA 10th Floor - Foothills Room
Astrophysics Lunch Seminar
TBA

Erika Zetterlund,
CASA
Fri, April 07 4:00pm
JILA Auditorium
Phys Chem/Chem Phys Seminar
TBA

Hanna Reisler,
University of Southern California
Mon, April 10 4:00pm
Duane Physics Room G125
Nuclear/Particle Physics Seminar
p-adic AdS/CFT

Steve Gubser,
Princeton University

Abstract/Details

p-adic numbers are an elaboration of the arithmetic one uses to reckon days of the week. p-adic AdS/CFT is a formulation of the gauge-string duality where the conformal field theory is defined over p-adic numbers, and anti-de Sitter space is replaced by an infinite regular tree, sometimes called the Bethe lattice. I will explain this new version of AdS/CFT, illustrate with a few computations, and at the end also explain how some old ideas like Kadanoff's spin-blocking fit in elegantly to the p-adic picture.
Mon, April 10 4:00pm
JILA Auditorium
Astrophysical & Planetary Sciences Seminar
Multiphase Gas Flows in Gaseous Galaxy Halos

Jessica Werk,
University of Washington

Abstract/Details

The circumgalactic medium (CGM; non-ISM gas within a galaxy virial radius) regulates the gas flows that shape the assembly and evolution of galaxies. Owing to vastly improved capabilities in space-based UV spectroscopy with the installation of HST/COS, observations and simulations of the CGM have emerged as the new frontier of galaxy evolution studies. My recent work suggests a rapid cycling of massive amounts of gas on scales of hundreds of kiloparsecs that in turn has raised pressing questions concerning the physical characteristics of the gas in the halos of galaxies. In this talk, I will discuss new constraints we have placed on the origin and fate of this material by studying the gas kinematics, metallicity and ionization state. I will conclude by posing several unanswered questions about the CGM that may be addressed with future survey data and hydrodynamic simulations in a cosmological context.
Tue, April 11 2:00pm
JILA X317
JILA Thesis Defense
Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces

Ameila Zutz,
JILA, Nesbitt group

Abstract/Details

Detailed molecular scale interactions at the gas–liquid interface are explored with quantum state-to-state resolved molecular scattering of a jet-cooled beam of NO(2Π1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered rovibronic state distributions are probed via laser-induced fluorescence, which provide insight into energy transfer and scattering pathways at the surface. These collision dynamics are explored as a function of incident collision energy, surface temperature (Ts), scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational and electronic excitation of NO at the gas-liquid interface. Rotational distributions observed are representative of two distinct scattering pathways, (i) molecules that thermalize and then desorb from the surface, and (ii) those that impulsively scatter. Thermally desorbing molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities. NO, a radical with multiple low-lying electronic states, also serves as an ideal candidate for exploring collision dynamics at these conductive liquid surfaces, where significant excitation is observed from ground (2Π1/2) to excited (2Π3/2) spin–orbit states. Electron-hole pair mediated vibrational excitation of NO at Ts >1000 K molten metals surfaces (Ga and Au) is also observed. These results highlight the presence of electronically nonadiabatic effects at gas–liquid interfaces and build toward a more complete characterization of energy transfer and dynamics at liquid surfaces. 
Wed, April 12 3:30pm
JSCBB Butcher Auditorium
Biochemistry Seminar
TBA

Dan Herschlag,
Stanford University
Wed, April 12 4:00pm
Duane Physics Room G1B20
Physics Department Colloquium
TBA

Brad Sewick,
McGill University
Thu, April 13 12:00pm
Duane Physics Room G126
Condensed Matter Seminar
TBA

Rafael Fernandes,
University of Minnesota
Thu, April 13 2:00pm
JILA X317
JILA Public Seminar
Thin Film Photovoltaics from Earth Abundant Materials: The Good, The Bad and The Promise

Richard Haight,
IBM TJ Watson Research Center

Abstract/Details

Numerous requirements are imposed on photovoltaic (PV) materials subject to their specific applications but, above all, efficiency is of paramount importance. Beyond that, a multitude of issues loom, including availability and toxicity of the constituent elements, overall cost and industrially efficient fabrication methods. While arguably no one particular PV technology provides a complete solution to these myriad issues, earth abundant multielement thin film absorbers such as CZTS,Se-Cu2ZnSn(SxSe1-x)4 and its variants are a group of materials that hold great promise but present significant challenges. The hope is that these absorbers can be utilized to reach terawatt level, solar based renewable energy generation. But, as we have discovered, the high density of intrinsic bulk defects limits achievable open circuit voltage (Voc) and efficiency. In this talk I will review the status of our knowledge of performance limiting defects and describe several approaches we have taken to solve these problems. These include elemental substitution to reduce intrinsic defects and re-engineering of the back contact to drive higher voltages. I will describe the use of femtosecond UPS/photovoltage spectroscopy to extract band alignments at both the front and back surfaces, critical to high performance. I will also describe Auger nanoprobe studies of grain boundaries and the opportunity to utilize the imaging capabilities at STROBE to gain greater insight into these critical interfaces. Finally, I will describe our most recent work to increase Voc of individual devices and our development of a monolithic, series-connected array to achieve > 5.5V for powering autonomous devices for the “Internet-of-Things”.  
Fri, April 14 12:00pm
JILA 10th Floor - Foothills Room
Astrophysics Lunch Seminar
TBA

Eric Wolf,
LASP/ATOC
Fri, April 14 4:00pm
JILA Auditorium
Phys Chem/Chem Phys Seminar
TBA

Elad Harel,
Northwestern
Mon, April 17 4:00pm
JILA Auditorium
Astrophysical & Planetary Sciences Seminar
TBA

Tim Bastian,
NRAO, Charlottesville
Wed, April 19 3:30pm
JSCBB Butcher Auditorium
Biochemistry Seminar
TBA

Mike Rosen,
UT Southwestern Medical Center
Wed, April 19 4:00pm
Duane Physics Room G1B20
Physics Department Colloquium
TBA

Dana Anderson,
University of Colorado, Boulder
Thu, April 20 12:00pm
Duane Physics Room G126
Condensed Matter Seminar
TBA

Sagar Vijay
Fri, April 21 4:00pm
JILA Auditorium
Phys Chem/Chem Phys Seminar
TBA

Helmut Schwarz,
Technische Universitat Berlin
Sat, April 22 9:30am
Cristol Chemistry Room 140
CU Wizards Program
One Fish, Two Fish...Fluorescent Red & Green Squish

Amy Palmer
Mon, April 24 4:00pm
JILA Auditorium
Astrophysical & Planetary Sciences Seminar
Big Bang to Biosignatures: The LUVOIR Decadal Mission Concept

Aki Roberge,
Goddard Space Flight Center

Abstract/Details

The Large UV/Optical/IR Surveyor (LUVOIR) is a concept for a highly capable, multi-wavelength observatory with ambitious science goals. This mission would enable great leaps forward in a broad range of science, from the epoch of reionization, through galaxy formation and evolution, star and planet formation, to solar system remote sensing. LUVOIR also has the major goal of characterizing habitable exoplanets around Sun-like stars and searching them for signs of life. LUVOIR is one of four Decadal Survey Mission Studies initiated in Jan 2016. The final report will be submitted to NASA and then the US National Academies in 2019. Here I will summarize LUVOIR’s broad and revolutionary science goals. I’ll explain our current vision for the instrument suite and aperture sizes to be studied. Finally, I’ll discuss the study process and what will happen over the next years in preparation for the 2020 Decadal Survey.  
Wed, April 26 3:30pm
JSCBB Butcher Auditorium
Biochemistry Seminar
TBA

Robert Singer,
Albert Einstein College of Medicine
Wed, April 26 4:00pm
Duane Physics Room G1B20
Physics Department Colloquium
TBA

Jané Kondev,
Brandeis University
Thu, April 27 12:00pm
Duane Physics Room G126
Condensed Matter Seminar
TBA

Brent Fultz,
California Institute of Technology
Fri, April 28 12:00pm
JILA 10th Floor - Foothills Room
Astrophysics Lunch Seminar
TBA

David Kasper,
University of Wyoming
Mon, May 01 4:00pm
JILA Auditorium
Astrophysical & Planetary Sciences Seminar
TBA

Chung-Pei Ma,
University of California, Berkeley
Wed, May 03 4:00pm
Duane Physics Room G1B20
Physics Department Colloquium
TBA

Jennifer Hoffman,
Harvard University
Thu, May 04 12:00pm
Duane Physics Room G126
Condensed Matter Seminar
TBA

Jenny Hoffman,
Harvard University
Fri, May 05 10:30am
Duane Physics Room G126
CTQM Seminar
TBA

Tarun Grover,
University of California San Diego
Thu, May 11 12:00pm
Duane Physics Room G126
Condensed Matter Seminar
TBA

Maksym Serbyn
Fri, May 19 12:00pm
JILA 10th Floor - Foothills Room
Astrophysics Lunch Seminar
TBA

Baylee Bordwell,
LASP
Sat, May 20 9:30am
Cristol Chemistry Room 140
CU Wizards Program
The Chemistry of Energy

Steven George
Sat, June 17 9:30am
Duane Physics Room G1B30
CU Wizards Program
For Very Big to Very Small...Microscopy and the Powers of Ten

Tom Perkins

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