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Outreach In the past year, PI organized and participated in numerous outreach events:

Unusual Effects of High Porosity Aerogel on Superfluid 3 He Yoonseok Lee, University of Florida, DMR 0803516.

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Outreach In the past year, PI organized and participated in numerous outreach events:

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  1. Unusual Effects of High Porosity Aerogel on Superfluid 3HeYoonseok Lee, University of Florida, DMR 0803516 The effect of disorder on a many particle system is one of the most important and ubiquitous problems in condensed matter physics. We study the effect of controlled disorder in otherwise the purest condensed matter system, liquid 3He by utilizing nanometer scale porous medium, silica aerogel. It is expected that at moderate frequencie below about 50 MHz the ultrasound should be in hydrodynamic limit, exhibiting an f2-dependence in attenuation. However, our sound attenuation measurements conducted at four different frequencies revealed non-trivial frequency dependences in the B-like phase of superfluid in 98% porosity aerogel, progressively deviating from the expected hydrodynamic behavior as temperature lowers to the zero temperature limit. We interpret that this behavior is related to the structure of the impurity states induced by scattering off high porosity aerogel. Our observation could offer a tool to profile the gap structure in this system as electron tunneling spectroscopy does for superconductors. B.H. Moon et al., Phys. Rev. B 82, 060501 (2010). selected as an Editor’s Choice Sound attenuation as a function of frequency for select reduced temperatures at three different sample pressures of (a) 33 bar, (b) 25 bar, and (c) 14 bar. The sound attenuation is normalized by the attenuation at the superfluid transition temperature,Tca. The lines going through the data points are guides for eyes.

  2. Unusual Effects of High Porosity Aerogel on Superfluid 3HeYoonseok Lee, University of Florida, DMR 0803516 • OutreachIn the past year, PI organized and participated in numerous outreach events: • Hosted recruit events and lab tours for STARS local high school students and science teachers. • Served as a judge for the Science Fair at Hawthorne Middle/High School (Title 1 school located in an underrepresented area) since 2002. • Participated as a faculty advisor in DOE sponsored Regional Science Bowl for 2010 and 2011. The events were held in the Physics Department involving about 25 undergraduate and graduate students and two faculty advisors including the PI. The Florida-Georgia Louis Stokes Alliance for Minority Participation (FGLSAMP) FGLSAMP, an NSF Project, includes over 1000 talented undergraduates from 13 institutions with a mission to increase the number of bachelors degrees among the underrepresented students in the STEM disciplines. Eric Garcell, mentored by the PI, received a FGLSAMP Scholarship and won the 3rd place in the Oral Presentation Competition (Physics) in 2011, presenting “Simulations of a MEMS Actuator”. Eric is the second student of the PI following Eddie Callela who won the first place in 2005 and currently pursuing a PhD degree in Physics at U. of Colorado at Boulder.

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