Broadcast

The Broadcast side of the Physics Colloquium.

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Colloquiums that were recorded in 2002:

Feb. 8th
Speaker:
David Fahey, National Oceanic and Atmospheric Administration

Title:
"Ozone Depletion and Climate Change Major Issues of Our Time"

Abstract:
Studies of atoms in which one electron is excited to a state of are principal quantum number n are described. Such atoms possess unusual physical characteristics. At high n, the classical electron orbital period Tn is very large (Tn ~ 10 ns at n ~ 400) allowing application of unidirectional electric field pulses, termed half-cycle pulses (HCPs), whose duration is <<Tn. In this limit, the HCP simply delivers an impulsive momentum transfer or "kick" to the excited electron. This opens up new opportunities for the control and manipulation of atomic wavefunctions and for testing classical-quantum correspondence. In addition, the "kicked" atom provides a new paradigm for the study of nonlinear dynamics in Hamiltonian systems and many interesting effects such as dynamical stabilization and quantum localization are evident. Rydberg atoms are strongly perturbed by the presence of a nearby metal surface. Image charge effects lead to formation of hybridized states similar to Start states that can be oriented towards, parallel to, or away from the surface. Ionization can occur through tunneling of the excited electron into vacant levels in the metal. Rydberg atom measurements can thus provide new insights into charge transfer and electron tunneling during atom/surface interactions and into surface-induced atomic perturbations

Feb. 15th
Speaker:
Christopher T. Hill, Fermi National Accelerator Laboratory

Title:
"Deconstructing Extra Dimensions"

Abstract:
Latticizing, or deconstructing, extra space dimensions is a powerful new tool for obtaining an effective description of associated new particles and their interactions. This leads us to a new view as to what the Higgs boson may actually be, and how the effects of hidden extra dimensions of space will be manifested in laboratory experiments. Top Quark condensation and the Top Quark Seesaw are obtained in the limit of critical coupling on brane n and decoupling all but a few of the nearest neighboring branes.

Feb. 22nd
Speaker:
Robert R. Caldwell, Dartmouth College

Title:
"Dark Energy in the Universe"

Abstract:
Three recent developments in observation and experiment have reshaped our understanding of the Universe. These are the low matter density in baryons and cold dark matter, inferred from the mass and abundance of clusters; the accelerating cosmic expansion, based on the distance-redshift relationship using type 1a supernovae; the flat spatial geometry, determined by measurements of the cosmic microwave background.It is becoming apparent that the vast majority of the energy of the Universe is in the form of a hitherto undiscovered substance -- "dark energy." To reveal and understand the nature of this dark energy is a challenge both to experiment and theory. In this talk, I will describe several possible candidates for the dark energy-- a cosmological constant, and the dynamical "Quintessence" -- while focusing on observational tests and the connection to fundamental theory.

Mar. 15th
Speaker:
Ruth Howes, Ball State University

Title:
"Undergraduate Physics in the Age of Compassionate Conservatism"

Abstract:
Physics departments currently face significant changes in the environment in which they operate. Physics and physics research constantly change, and so does funding for these activities. The current generation of students brings new skills to the university. Physics graduates face a changing workplace. Universities, particularly public ones, are under pressure from a variety of sources. Over the last ten years, the number of students graduating with bachelors degrees in physics education has dramatically declined. The National Task Force on Undergraduate Physics formed by APS, AAPT, and AIP has launched a project to identify responses by undergraduate departments that are thriving in this environment. The preliminary results of this project provide a snapshot of the state of undergraduate physics.

Sept. 27
Speaker:
Tony Tyson, Bell Labs, Lucent Technologies

Title:
"Gravitational Tomography"

Abstract:
There is evidence for vacuum energy accelerating the recent expansion of the universe. Does this "dark energy" exist? What is it's equation of state? A new and direct probe of dark energy is provided by 3-D mass tomography. Dark matter may be "seen" directly via its coherent gravitational lens warping of thousands of high redshift galaxy images. Tomographic inversion of these cosmic mirages in deep wide-field imaging surveys enables a unique 3-D mass view of our universe. Images of dark matter structures and their development over cosmic time will sharply constrain dark energy and its physical properties. These multiple weak lens probes complement those from cosmic background radiation and supernovae, and thus test the consistency of our cosmology. The Deep Lens Survey, and plans for the Large Synoptic Survey Telescope will be reviewed.
        Related links:
        http://dls.bell-labs.com
        http://lssto.org

Oct. 4th
Speaker:
Paul Chaikin, Princeton University

Title:
"Trillions of Quantum Dots, Fingerprints, Nanolithography with Diblock Copolymers and the Annealing of Stripes"

Abstract:
In order to develop new technologies for lithography on the nanometer scale we have been investigating the use of diblock copolymers, systems which form periodic structures on the 5-50 nm scale. Diblock copolymers consist of A and B monomers which are immiscible and would normally phase separate like oil and water. When they are covalently bound as A-A-A-A-B-B-B-B-B-B the best they can do to avoid each other is to put all the A ends together in spheres or cylinders surrounded by the B's. We have used a monolayer mask of the diblock to transfer the periodic patterns to a number of different substrates as holes, posts, and semiconductor and metal quantum dots producing ultradense arrays, e.g. 3 trillion dots on a 3 inch wafer. Along the way we have developed novel methods for three dimensional imaging on the nanometer scale and for tracking the annealing of the two dimensional monolayer patterns. Time lapse atomic force microscopy of the cylindrical phase (which forms fingerprint like patterns in the monolayer) reveals the solution to a common problem in many fields of science, how striped patterns order. Instead of two defects annihilating our movies show quadrupole annihilation explaining the much slower (fourth root time) behavior seen in many striped systems.

Nov. 1st
Speaker:
Robert B. Griffiths, Physics Department, Carnegie-Mellon University

Title:
"Understanding Quantum Mechanics"

Abstract:
Standard textbooks introduce probabilities into quantum theory by assigning a special role to measurements. This and the associated wave function collapse give rise to various paradoxes and conceptual difficulties. These can be avoided by making probabilities part of the dynamical laws governing the time evolution of all quantum systems, whether or not they are being measured. Doing this in a consistent way requires that one pay attention to special rules, reflecting the mathematical (Hilbert space) structure of the theory, restricting how two or more quantum descriptions can be combined. These rules will be discussed using the quantization of spin angular momentum, as exhibited in the experiment of Stern and Gerlach.
     The Notes:

Nov. 8th
Speaker:
Roger Dixon, Fermilab

Title:
"Prospects for the Direct Detection of Dark Matter in the Cryogenic Dark Matter Search (CDMS)"

Abstract:
CDMS has set very competitive detection limits for dark matter by running at a shallow site underneath the Stanford campus. In this talk the motivation for detecting dark matter in the laboratory will be reviewed, and the cryogenic detection technique used by CDMS will be outlined. In addition, preliminary results obtained at Stanford using cryogenic detectors will be presented. Finally, the status and prospects for running at a deep site in the Soudan Laboratory will be discussed.
www.fnal.gov/pub/inquiring/virtual/roger_cv.html

Feb. 8th	Speaker:	David Fahey, National Oceanic and Atmospheric Administration
	Title:	"Ozone Depletion and Climate Change Major Issues of Our Time"
	Abstract:	Studies of atoms in which one electron is excited to a state of are principal quantum number n are described. Such atoms possess unusual physical characteristics. At high n, the classical electron orbital period Tn is very large (Tn ~ 10 ns at n ~ 400) allowing application of unidirectional electric field pulses, termed half-cycle pulses (HCPs), whose duration is <<Tn. In this limit, the HCP simply delivers an impulsive momentum transfer or "kick" to the excited electron. This opens up new opportunities for the control and manipulation of atomic wavefunctions and for testing classical-quantum correspondence. In addition, the "kicked" atom provides a new paradigm for the study of nonlinear dynamics in Hamiltonian systems and many interesting effects such as dynamical stabilization and quantum localization are evident. Rydberg atoms are strongly perturbed by the presence of a nearby metal surface. Image charge effects lead to formation of hybridized states similar to Start states that can be oriented towards, parallel to, or away from the surface. Ionization can occur through tunneling of the excited electron into vacant levels in the metal. Rydberg atom measurements can thus provide new insights into charge transfer and electron tunneling during atom/surface interactions and into surface-induced atomic perturbations

Feb. 15th	Speaker:	Christopher T. Hill, Fermi National Accelerator Laboratory
	Title:	"Deconstructing Extra Dimensions"
	Abstract:	Latticizing, or deconstructing, extra space dimensions is a powerful new tool for obtaining an effective description of associated new particles and their interactions. This leads us to a new view as to what the Higgs boson may actually be, and how the effects of hidden extra dimensions of space will be manifested in laboratory experiments. Top Quark condensation and the Top Quark Seesaw are obtained in the limit of critical coupling on brane n and decoupling all but a few of the nearest neighboring branes.

Feb. 22nd	Speaker:	Robert R. Caldwell, Dartmouth College
	Title:	"Dark Energy in the Universe"
	Abstract:	Three recent developments in observation and experiment have reshaped our understanding of the Universe. These are the low matter density in baryons and cold dark matter, inferred from the mass and abundance of clusters; the accelerating cosmic expansion, based on the distance-redshift relationship using type 1a supernovae; the flat spatial geometry, determined by measurements of the cosmic microwave background.It is becoming apparent that the vast majority of the energy of the Universe is in the form of a hitherto undiscovered substance -- "dark energy." To reveal and understand the nature of this dark energy is a challenge both to experiment and theory. In this talk, I will describe several possible candidates for the dark energy-- a cosmological constant, and the dynamical "Quintessence" -- while focusing on observational tests and the connection to fundamental theory.

Mar. 15th	Speaker:	Ruth Howes, Ball State University
	Title:	"Undergraduate Physics in the Age of Compassionate Conservatism"
	Abstract:	Physics departments currently face significant changes in the environment in which they operate. Physics and physics research constantly change, and so does funding for these activities. The current generation of students brings new skills to the university. Physics graduates face a changing workplace. Universities, particularly public ones, are under pressure from a variety of sources. Over the last ten years, the number of students graduating with bachelors degrees in physics education has dramatically declined. The National Task Force on Undergraduate Physics formed by APS, AAPT, and AIP has launched a project to identify responses by undergraduate departments that are thriving in this environment. The preliminary results of this project provide a snapshot of the state of undergraduate physics.

Sept. 27	Speaker:	Tony Tyson, Bell Labs, Lucent Technologies
	Title:	"Gravitational Tomography"
	Abstract:	There is evidence for vacuum energy accelerating the recent expansion of the universe. Does this "dark energy" exist? What is it's equation of state? A new and direct probe of dark energy is provided by 3-D mass tomography. Dark matter may be "seen" directly via its coherent gravitational lens warping of thousands of high redshift galaxy images. Tomographic inversion of these cosmic mirages in deep wide-field imaging surveys enables a unique 3-D mass view of our universe. Images of dark matter structures and their development over cosmic time will sharply constrain dark energy and its physical properties. These multiple weak lens probes complement those from cosmic background radiation and supernovae, and thus test the consistency of our cosmology. The Deep Lens Survey, and plans for the Large Synoptic Survey Telescope will be reviewed. Related links: http://dls.bell-labs.com http://lssto.org

Oct. 4th	Speaker:	Paul Chaikin, Princeton University
	Title:	"Trillions of Quantum Dots, Fingerprints, Nanolithography with Diblock Copolymers and the Annealing of Stripes"
	Abstract:	In order to develop new technologies for lithography on the nanometer scale we have been investigating the use of diblock copolymers, systems which form periodic structures on the 5-50 nm scale. Diblock copolymers consist of A and B monomers which are immiscible and would normally phase separate like oil and water. When they are covalently bound as A-A-A-A-B-B-B-B-B-B the best they can do to avoid each other is to put all the A ends together in spheres or cylinders surrounded by the B's. We have used a monolayer mask of the diblock to transfer the periodic patterns to a number of different substrates as holes, posts, and semiconductor and metal quantum dots producing ultradense arrays, e.g. 3 trillion dots on a 3 inch wafer. Along the way we have developed novel methods for three dimensional imaging on the nanometer scale and for tracking the annealing of the two dimensional monolayer patterns. Time lapse atomic force microscopy of the cylindrical phase (which forms fingerprint like patterns in the monolayer) reveals the solution to a common problem in many fields of science, how striped patterns order. Instead of two defects annihilating our movies show quadrupole annihilation explaining the much slower (fourth root time) behavior seen in many striped systems.

Nov. 1st	Speaker:	Robert B. Griffiths, Physics Department, Carnegie-Mellon University
	Title:	"Understanding Quantum Mechanics"
	Abstract:	Standard textbooks introduce probabilities into quantum theory by assigning a special role to measurements. This and the associated wave function collapse give rise to various paradoxes and conceptual difficulties. These can be avoided by making probabilities part of the dynamical laws governing the time evolution of all quantum systems, whether or not they are being measured. Doing this in a consistent way requires that one pay attention to special rules, reflecting the mathematical (Hilbert space) structure of the theory, restricting how two or more quantum descriptions can be combined. These rules will be discussed using the quantization of spin angular momentum, as exhibited in the experiment of Stern and Gerlach. The Notes:

Nov. 8th	Speaker:	Roger Dixon, Fermilab
	Title:	"Prospects for the Direct Detection of Dark Matter in the Cryogenic Dark Matter Search (CDMS)"
	Abstract:	CDMS has set very competitive detection limits for dark matter by running at a shallow site underneath the Stanford campus. In this talk the motivation for detecting dark matter in the laboratory will be reviewed, and the cryogenic detection technique used by CDMS will be outlined. In addition, preliminary results obtained at Stanford using cryogenic detectors will be presented. Finally, the status and prospects for running at a deep site in the Soudan Laboratory will be discussed. www.fnal.gov/pub/inquiring/virtual/roger_cv.html