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Events on Wednesday, March 30th, 2016

R. G. Herb Condensed Matter Seminar
Cooling and stabilization of levitated graphite nanoplatelets
Time: 10:00 am
Place: 5310 Chamberlin Hall
Speaker: Pavel Nagornykh, University of Maryland
Abstract: The discovery of graphene in 2004 led to a new spike of interest in 2D materials, with many new ones uncovered and studied in the last ten years. At the same time, it became apparent how important it is to minimize interaction between the 2D sample and the environment and, ideally, to separate them completely. One of the ways to solve this problem was proposed in 2010 by Bruce Kane in experiment, where the graphite microparticles were levitated in a quadrupole ion trap.

In this talk, I'm going to discuss our progress on learning how to control these levitated particles in high vacuum conditions, where a feedback cooling is required. I will present our results, which include cooling down the translational motion of the particles down to 20K and study of the effect of stray electric fields on the efficiency of the feedback cooling. Finally, I'm going to talk about our most recent work on locking nanoplatelets' rotation to an external RF fields, which allows us to tune their spinning frequency as well as the spinning axis orientation. This shows that we are close to having full control over both translational and rotational degrees of freedom for the levitated graphite flakes, which is a crucial condition for further research on levitated 2D materials.
Host: McDermott
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Department Meeting
Time: 12:15 pm
Place: 5310 Chamberlin Hall
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NPAC (Nuclear/Particle/Astro/Cosmo) Forum
Accelerating the Search for Cosmic Accelerators
Time: 2:00 pm - 3:00 pm
Place: 5280 Chamberlin Hall
Speaker: Amanda Weinstein, Iowa State University
Abstract: Over the past 15 years, gamma-ray observations have become a cornerstone of the rapidly expanding field of multi-messenger astronomy. Gamma-ray astronomy has helped revolutionize our view of the non-thermal universe and galvanized our search for the powerful natural particle accelerators found throughout the cosmos. These advances have relied on the capabilities of both the Fermi Gamma-ray Space Telescope (sensitive to energies between 30 MeV and 1 TeV) and the ground-based very high energy (VHE; E>85 GeV) gamma-ray observatories VERITAS, H.E.S.S., MAGIC, and HAWC.

Our progress has left us with as many new questions as we have answers. In the long term, these fresh questions may be addressed by next-generation observatories using new technology. However, much can be done now by expanding the capabilities of existing instruments and by more effectively combining data from the different observatories. I will outline a promising new approach that extends the reach of the gamma-ray observatory VERITAS while providing a natural context for combining data from multiple instruments. I will also consider the application of this approach to several of the field's outstanding questions and goals.
Host: Albrecht Karle
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