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Colloquiums that were recorded in Spring Semester of 2000:

Feb. 11th
Speaker:
Sridhara Rao Dasu, University of Wisconsin, Madison

Title:
"Experiments to understand the origin of mass and matter excess in our universe"

Abstract:
In spite of the amazing success of the Standard Model in explaining phenomenon ranging from few hundred MeV Pi meson production up to several hundred GeV top quark pair production, there are left some important questions that require experimental investigation. The most fundamental of these questions that beg for further research involve the Higgs mechanism that explains the origin of mass and the CP violation phenomenon that results in matter-antimatter asymmetry. The BaBar experiment at SLAC B-Factory that is collecting data at the Upsilon 4S resonance now, is gearing up to understand CP violation phenomenon. The CMS experiment at CERN Large Hadron Collider that will investigate proton-proton collisions at 14 TeV center of mass energy is designed to investigate the energy frontier and address the question of the origin of mass. Initial performance of the BaBar experiment and the physics potential of both these experiments will be discussed.

March 3rd
Speaker:
Deborah Jin, JILA & National Institute of Standards of Technology

Title:
"Degenerate Atomic Fermi Gases"

Abstract:
Fermions are ubiquitous in nature and their quantum behavior is responsible for the periodic table and the stability of matter. However low density, weakly interacting Fermi systems are exceedingly rare. Building on the technologies that were used to produce the first dilute gas Bose-Einstein condensates in 1995, we have cooled a million potassium-40 atoms to temperatures below a microKelvin and observed effects of the Fermi-Dirac quantum statistics. The atoms are first laser cooled and trapped out of a room temperature vapor. Following this initial cooling, the atoms are magnetically confined and further cooled via forced evaporation. I will discuss the consequences of the fermionic nature of the atoms on the evaporative cooling process and present measurements of the quantum statistics at our lowest tem.

Mar. 31st
Speaker:
Dale Meade, Princeton University

Title:
"Confining a Fusion Fire - A Grand Challenge for Science and Technology"

Abstract:
Fusion is the primary source of energy for the universe, and represents a potentially attractive source of abundant and environmentally benign energy for the world. For decades scientists have searched for techniques to heat the plasma fuel to fusion temperatures (>100 million C) and confine this fusion fire for the time necessary to produce net energy. During the last decade, plasma temperatures of >300 million C have been produced in the laboratory using systems with strong magnetic fields and the confinement is approaching that needed for net energy production in the plasma. Nonetheless, tremendous technical challenges in science and technology remain that must be overcome to make fusion power a practical reality. (http://fire.pppl.gov)

April 21st
Speaker:
Brenda Dingus, University of Wisconsin, Madison

Title:
"The Highest Energy Gamma-Rays from Gamma-Ray Bursts"

Abstract:

Oct. 13th
Speaker:
Prof. J. C. Séamus Davis, Univ. of California-Berkeley

Title:
"Exploring High-TC Superconductivity: One Atom at a Time"

Abstract:
Scanning tunneling microscopy (STM) at individual impurity atoms is a new tool[1] with which to probe high temperature superconductivity. Impurity atoms in conventional materials like semiconductors are well known to create bound quantum states for the conduction electrons. Theory predicts that a new type of bound quantum state, characteristic of d-wave superconductivity, will exist at impurity atoms in the high temperature superconductors [2]. Microscopic theories of the mechanism of superconductivity could be tested with atomic-scale information about such states. I will describe a series of experiments on the high-Tc superconductor Bi2Sr2CaCu2Od-? in which these states were discovered [1]. I will then discuss measurements of their properties at individual Ni and Zn impurity atoms in Bi2Sr2CaCu2Od- ? [3]. Finally, I hope to discuss newly emerging phenomena associated with the O dopant atoms (which convert the materials from antiferromagnetic insulators to superconductors) and the implications of these phenomena for the mechanism of superconductivity. This project was carried out in collaboration with K. M. Lang and V. Madhavan (Berkeley), E. W. Hudson (NIST Gaithersburg) S. H. Pan (Boston University), H. Eisaki (Stanford) and S. Uchida (Tokyo University).
[1] Science 285, 88 (1999)
[2] Phys. Rev. B 51, 15547 (1995)
[2] Nature 403, 746 (2000)

Nov. 10th
Speaker:
Carl Anderson, IBM

Title:
"Design of the IBM Power4 Processor"

Abstract:
The POWER4 processor chip is one of the most complex processor chips to date with 2 microprocessor cores, a shared L2, and L3 directory and a switch fabric for large SMPs. The system and physical design will be described.

Nov. 17th
Speaker:
Robert Brandenberger, Brown University

Title:
"Inflationary Cosmology: Progress and Problems"

Abstract:
Inflationary cosmology has become a cornerstone of modern cosmology. In addition to explaining some of the puzzles of standard big bang cosmology, the inflationary Universe scenario makes predictions for observables, some of which have been spectacularly confirmed by recent experiments. In spite of this success, inflationary cosmology is plagued by important conceptual problems. After reviewing the basics of inflationary cosmology, the colloquium will focus on some areas of recent progress (such as reheating and the theory of cosmological perturbations), and on some of the conceptual problems (e.g. the singularity and cosmological constant problems). Some new approaches to addressing the conceptual problems will be mentioned.
More

Dec. 1st
Speaker:
Jim Truran, University of Chicago

Title:
"Abundances as Tracers of the Star Formation Histories of Galaxies"

Abstract:
To the extent that the history of the Galaxy is to be found written in the composition of its component stars and gas, its abundance history can be used to probe and to constrain its dynamical and star formation history. Since distinctive abundance patterns are characteristic of nucleosynthesis occurring in stars of different masses and corresponding lifetimes, interesting constraints on the star formation and nucleosynthesis histories may be contained in the abundance histories of halo and disc population stars and QSO absorption line systems. A brief review will be presented of our knowledge of abundances in low metallicity populations, in light of current predictions of nucleosynthesis theory. Questions to be addressed include: Is there a need for a Population III? Do normal stars suffice to explain all observed abundance features in our Galaxy and other galaxies? What were the star formation histories of the halo, bulge, and disk of our Galaxy?

Feb. 11th	Speaker:	Sridhara Rao Dasu, University of Wisconsin, Madison
	Title:	"Experiments to understand the origin of mass and matter excess in our universe"
	Abstract:	In spite of the amazing success of the Standard Model in explaining phenomenon ranging from few hundred MeV Pi meson production up to several hundred GeV top quark pair production, there are left some important questions that require experimental investigation. The most fundamental of these questions that beg for further research involve the Higgs mechanism that explains the origin of mass and the CP violation phenomenon that results in matter-antimatter asymmetry. The BaBar experiment at SLAC B-Factory that is collecting data at the Upsilon 4S resonance now, is gearing up to understand CP violation phenomenon. The CMS experiment at CERN Large Hadron Collider that will investigate proton-proton collisions at 14 TeV center of mass energy is designed to investigate the energy frontier and address the question of the origin of mass. Initial performance of the BaBar experiment and the physics potential of both these experiments will be discussed.

March 3rd	Speaker:	Deborah Jin, JILA & National Institute of Standards of Technology
	Title:	"Degenerate Atomic Fermi Gases"
	Abstract:	Fermions are ubiquitous in nature and their quantum behavior is responsible for the periodic table and the stability of matter. However low density, weakly interacting Fermi systems are exceedingly rare. Building on the technologies that were used to produce the first dilute gas Bose-Einstein condensates in 1995, we have cooled a million potassium-40 atoms to temperatures below a microKelvin and observed effects of the Fermi-Dirac quantum statistics. The atoms are first laser cooled and trapped out of a room temperature vapor. Following this initial cooling, the atoms are magnetically confined and further cooled via forced evaporation. I will discuss the consequences of the fermionic nature of the atoms on the evaporative cooling process and present measurements of the quantum statistics at our lowest tem.

Mar. 31st	Speaker:	Dale Meade, Princeton University
	Title:	"Confining a Fusion Fire - A Grand Challenge for Science and Technology"
	Abstract:	Fusion is the primary source of energy for the universe, and represents a potentially attractive source of abundant and environmentally benign energy for the world. For decades scientists have searched for techniques to heat the plasma fuel to fusion temperatures (>100 million C) and confine this fusion fire for the time necessary to produce net energy. During the last decade, plasma temperatures of >300 million C have been produced in the laboratory using systems with strong magnetic fields and the confinement is approaching that needed for net energy production in the plasma. Nonetheless, tremendous technical challenges in science and technology remain that must be overcome to make fusion power a practical reality. (http://fire.pppl.gov)

April 21st	Speaker:	Brenda Dingus, University of Wisconsin, Madison
	Title:	"The Highest Energy Gamma-Rays from Gamma-Ray Bursts"
	Abstract:

Oct. 13th	Speaker:	Prof. J. C. Séamus Davis, Univ. of California-Berkeley
	Title:	"Exploring High-TC Superconductivity: One Atom at a Time"
	Abstract:	Scanning tunneling microscopy (STM) at individual impurity atoms is a new tool[1] with which to probe high temperature superconductivity. Impurity atoms in conventional materials like semiconductors are well known to create bound quantum states for the conduction electrons. Theory predicts that a new type of bound quantum state, characteristic of d-wave superconductivity, will exist at impurity atoms in the high temperature superconductors [2]. Microscopic theories of the mechanism of superconductivity could be tested with atomic-scale information about such states. I will describe a series of experiments on the high-Tc superconductor Bi2Sr2CaCu2Od-? in which these states were discovered [1]. I will then discuss measurements of their properties at individual Ni and Zn impurity atoms in Bi2Sr2CaCu2Od- ? [3]. Finally, I hope to discuss newly emerging phenomena associated with the O dopant atoms (which convert the materials from antiferromagnetic insulators to superconductors) and the implications of these phenomena for the mechanism of superconductivity. This project was carried out in collaboration with K. M. Lang and V. Madhavan (Berkeley), E. W. Hudson (NIST Gaithersburg) S. H. Pan (Boston University), H. Eisaki (Stanford) and S. Uchida (Tokyo University). [1] Science 285, 88 (1999) [2] Phys. Rev. B 51, 15547 (1995) [2] Nature 403, 746 (2000)

Nov. 10th	Speaker:	Carl Anderson, IBM
	Title:	"Design of the IBM Power4 Processor"
	Abstract:	The POWER4 processor chip is one of the most complex processor chips to date with 2 microprocessor cores, a shared L2, and L3 directory and a switch fabric for large SMPs. The system and physical design will be described.

Nov. 17th	Speaker:	Robert Brandenberger, Brown University
	Title:	"Inflationary Cosmology: Progress and Problems"
	Abstract:	Inflationary cosmology has become a cornerstone of modern cosmology. In addition to explaining some of the puzzles of standard big bang cosmology, the inflationary Universe scenario makes predictions for observables, some of which have been spectacularly confirmed by recent experiments. In spite of this success, inflationary cosmology is plagued by important conceptual problems. After reviewing the basics of inflationary cosmology, the colloquium will focus on some areas of recent progress (such as reheating and the theory of cosmological perturbations), and on some of the conceptual problems (e.g. the singularity and cosmological constant problems). Some new approaches to addressing the conceptual problems will be mentioned. More

Dec. 1st	Speaker:	Jim Truran, University of Chicago
	Title:	"Abundances as Tracers of the Star Formation Histories of Galaxies"
	Abstract:	To the extent that the history of the Galaxy is to be found written in the composition of its component stars and gas, its abundance history can be used to probe and to constrain its dynamical and star formation history. Since distinctive abundance patterns are characteristic of nucleosynthesis occurring in stars of different masses and corresponding lifetimes, interesting constraints on the star formation and nucleosynthesis histories may be contained in the abundance histories of halo and disc population stars and QSO absorption line systems. A brief review will be presented of our knowledge of abundances in low metallicity populations, in light of current predictions of nucleosynthesis theory. Questions to be addressed include: Is there a need for a Population III? Do normal stars suffice to explain all observed abundance features in our Galaxy and other galaxies? What were the star formation histories of the halo, bulge, and disk of our Galaxy?