Physics Department Current Events
"Current Topics in Physics" Physics 55100
Wednesday, December 11, 2013
11:00 PM to 12:00 PM, Marshak Science Building, Room 417
Mr. Rezlind BushatiPhysics Student, CCNY
"Detecting neutrino oscillations from the beta-decay of 8B in the sun through a D2O Cherenkov Detector"
The solar neutrino problem has been a topic of discussion since the mid 20th century, and has brought out different possible solutions to the problem. The nuclear processes of the sun create electron neutrinos which arrive at the earth with little resistance due to their small interactions with the fundamental forces. Experiments on the amount of neutrinos coming from the sun all brought back results which did not comply with theory, in that there were fewer neutrinos detected than predicted. One possible solution to this is the theory that neutrinos have mass, and also oscillate between their three lepton flavors. This suggests that the electron neutrinos being created at the sun’s core are capable changing flavors to the other two types of neutrinos as they travel to the earth’s detectors, which causes there to be less electron neutrinos being detected than predicted. By using a Cherenkov Detector filled with 1000 tons of heavy water, which would interact with the high energy neutrinos from the beta-decay of 8B in the sun, the Sudbury Neutrino Observatory provided results which are consistent with the predicted results by the Standard Solar Model, thus giving evidence that a fraction of the solar electron neutrinos are converted to muon neutrinos and tau neutrinos by the time they are detected.
Condensed Matter Seminar
Wednesday, December 18, 2013
12:15 PM to 1:15 PM, Marshak Science Building, Room 418N
Professor Xuan Gao
Case Western Reserve University
"Connecting the 2D Metal-Insulator Transition and Electron Liquid-Solid Transition in p-GaAs"
The metal-insulator transition (MIT) in various correlated 2D (two-dimensional) electron systems was speculated to be related to the formation of the Wigner solid due to strong Coulomb repulsion between carriers. The existence of 2D quantum Wigner solid was relatively well established in strong magnetic field where all the carriers fall in the lowest Landau level. But the zero field case remains unsettled. To address this issue, we have tracked the magnetic field induced Wigner solid in p-type GaAs quantum well as the interacting parameter increases from 20 to ~40, and found that the Wigner solid phase moves towards low field and eventually merges with the zero field MIT. Furthermore, studying the melting of Wigner solid against tuning parameters temperature, hole density, and magnetic field leads to strong evidence of an intermediate phase existing between the pure electron liquid and solid. In this interaction driven intermediate phase where Wigner solid bubbles coexist with Fermi liquid, the system tends to freeze upon raising temperature, a bizarre quantum phenomenon similar to the Pomeranchuk effect found in the mixture of liquid and solid Helium-3.
Physics Colloquia and Seminars are completed for the Fall semester. Please return to this page for events during the Spring 2014 semester, beginning January 29.
Assoc. Prof. Xuan Gao, Case Western Reserve University