TcSUH EventS
Bi-Weekly Seminar
Rutherford Scattering of Identical Ions-A Test of Quantum Mechanics at MeV Energies with Massive Particles
by: Ki B. Ma
Date: Friday February 20, 2004
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
Elastic Rutherford scattering between positively charged ions is mediated by the repulsive Coulomb potential. Its differential cross section according to classical mechanics comes out to be the same as the exact quantum mechanical result. Its characteristic 1/E2 energy dependence and cosec4(/2) angular dependence have been well established since 1911. Not predicted by Rutherford then, and missed in Goldberger and Watson2 even as late as 1964, these results break down when the scattering ions are identical, and oscillations in the differential cross section as a function of the scattering angle appear instead of the familiar smooth dependence. This behavior is thoroughly discussed in Landau and Liftshiz3 (1965), but the oscillations were summarily declared to vanish “on averaging over even a small range of values of. This oscillatory behavior is a hallmark of quantum mechanical interference. Dictated by the exchange symmetry of the scattering particles and without a classical counterpart, it constitutes a test for the validity of quantum mechanics versus classical mechanics, a test that can be conducted using massive particles at MeV energies, at room temperature. Here, we report preliminary results on the observation of quantum interference in the Rutherford scattering of carbon from carbon at incident energies between 1 and 4 MeV.
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Special Seminar
Theory of High-Temperature Superconductivity - A New Perspective
by: Prof. W. P. Su
Date: Friday January 16, 2004
Time: 12:00 pm – 1:00 pm
Location: Houston Science Center – Building 593 — Room 102
Overview
Theoretical analysis of an effective model of d-wave superconductivity in two dimensions reveals a subtle interplay between phase separation, superconductivity and antiferromagnetism. The main theoretical result can be described in terms of elementary phase separation concepts in a binary alloy. This provides a deep understanding of the phase diagram of a hole-doped cuprate superconductor. A microscopic model of d-wave superconductivity will also be discussed.
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