NSD Colloquia 2012
October 11, Thursday, 11:00 a.m. Bldg. 50-Auditorium
"Nearly Perfect Fluidity: From cold atoms to hot quarks and gluons"
Prof. Thomas Schaefer (North Carolina State University - Raleigh)
Abstract: A dimensionless measure of fluidity is the ratio of shear viscosity to entropy density. In this talk I will argue that fluidity is a sensitive probe of the strength of correlations in a fluid. I will also discuss evidence that the two most perfect fluids ever observed are also the coldest and the hottest fluid ever created in the laboratory. The two fluids are cold atomic gases (~10^-6^ K) that can be probed in optical traps, and the quark gluon plasma (~1012K) created in heavy ion collisions at RHIC and the LHC. Remarkably, both fluids come close to a bound on the shear viscosity that was first proposed based on calculations in string theory, involving non-equilibrium evolution of back holes in 5 (and more) dimensions.
May 30, Wednesday, 11:00 a.m. Building 50-Auditorium
"Shell Structure in Neutron-rich isotopes and the stability of nuclear matter"
Prof. Morten Hjorth-Jensen (University of Oslo / Michigan State University)
Abstract: To understand why matter is stable, and thereby shed light on the limits of nuclear stability, is one of the overarching aims and intellectual challenges of basic research in nuclear physics. Important properties of nuclear systems which can reveal information about these topics are for example masses, and thereby binding energies, and density distributions of nuclei. In this talk I will present some recent calculations on properties of oxygen, calcium and nickel isotopes towards their corresponding driplines and point to new experiments. In particular I will focus on ground state properties and excited states, with an emphasis on the role of two- and three-body forces using first principles methods like coupled-cluster theory. I will also try to outline present and future challenges to nuclear many-body theory and how to understand the above properties in terms of the underlying forces.
May 23, Wednesday, 11:00am, Building 54-Perseverance Hall #130
"Jet Tomography versus Jet Holography of Quark Gluon Plasmas”
Prof. Miklos Gyulassy (Columbia University)
Abstract: Recent data on nuclear modification jet observables in high energy nuclear collisions at RHIC and LHC energies will be addressed in terms of competing perturbative QCD based jet tomography and AdS/CFT gravity dual jet holography theories. The complementary experiments at RHIC and LHC provide stringent tests of the nature of jet-medium interactions in deconfined Quark Gluon Plasmas. The importance of future experiments at both RHIC and LHC capable of tagging charm and bottom quark jet flavors to differentiate between tomographic vs holographic models will be emphasized.
May 2, Wednesday, 11:00am, Building 50-Auditorium
"Jefferson Lab Science: Today and Tomorrow"
Prof. Robert D. McKeown (Thomas Jefferson Nat'l Accelerator Facility)
Abstract: The continuous electron beam accelerator facility at Jefferson Lab, built with novel superconducting radiofrequency (SRF) technology, provides opportunities to discover fundamental new aspects of the structure of visible matter – protons, neutrons and other bound states, and of the strong interaction, described by the gauge theory Quantum Chromodynamics. Jefferson Lab’s accelerator, in operation since 1995, is unique in the world and is currently undergoing a major upgrade to double its energy. The upgrade will bring new opportunities, not only in the study of hadronic matter, but also in searches for new physics, such as a suite of experiments to search for massive “dark photons”. The powerful SRF technology also enables a new generation of facilities in nuclear physics, particle physics, and applied sciences. In this talk, I will give an overview of Jefferson Lab’s current and future science program, including an outlook for the future of the laboratory.
March 14, Wednesday, 11:00am, Building 50-Auditorium
"Supernovae as Sources of Neutrinos and Elements"
Prof. Yongzhong Qian (University of Minnesota)
Abstract: Stars approximately 8 to 100 times heavier than the sun end their lives as core-collapse supernovae (CCSNe). In the process they emit a powerful burst of neutrinos, produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for stars producing CCSNe results in widely varying explosion energy, neutrino signals, and nucleosynthesis products. Recent progress in theoretical and observational studies of CCSNe is reviewed in connection with neutrino emission and nucleosynthesis. The prospects of using CCSNe as a unique laboratory to study neutrino oscillations are discussed.
February 29, Wednesday, 11:00am, Building 50-Auditorium
"The Search for Dark Matter with the XENON Experiment"
Prof. Elena Aprile (Columbia University)
Abstract: The XENON experiment is designed to search for dark matter Weakly Interacting Massive Particles (WIMPs) with a 3D position sensitive liquid xenon time projection chamber (LXeTPC) in which the light and charge signals produced by WIMP interactions are simultaneously detected. The current XENON100 experiment uses 160 kg of LXe of which 61 kg as WIMP target and 99 kg as active shield. The combination of target mass and extremely low background make XENON100 one of the most sensitive dark matter direct detection experiment in operation today. Located deep underground at the Gran Sasso National Laboratory in Italy, XENON100 continues to accumulate data and a blind analysis is in progress. I will review the status of the experiment, of the data analysis and some of the work towards the next generation XENON1T experiment.
February 8, Wednesday, 11:00am, Building 50-Auditorium
"The Legacy of Rutherford: a Centennial Perspective on Nuclear Physics"
Dr. John Schiffer (Argonne Nat'l Laboratory)
Abstract: In 1911 Rutherford discovered that at the core of atoms there is a very massive, electrically charged, nucleus. This experimental discovery brought about a major revolution in our understanding of the physical world in which we find ourselves. I will attempt to review the shifting focus and some of the major milestones in the research engendered by Rutherford's discovery. Enormous progress has been made in a 100 years, but there is still a great deal that we do not understand about the properties of the hadronic matter that makes up virtually all of the visible mass of the Universe.
January 20, Friday, 11:00am, Building 54-Perseverance Hall
"Nuclear Science at the Intensity Frontier”
Prof. Michael Ramsey-Musolf (University of Wisconsin, Madison)
Abstract: The quest to explain nature's fundamental interactions and how they shaped the evolution of the universe is one of the most compelling in modern science. The standard model of particle physics provides a partial explanation, but we know that it must be part of a larger, more complete framework. Experiments hoping to uncover details of the "new standard model" are being carried out at three frontiers: the high-energy frontier, involving facilities such as the Large Hadron Collider; the astrophysical frontier; and the "intensity frontier". In this talk, I discuss some of the opportunities for nuclear science to make key contributions to the search for new physics at the intensity frontier. I focus in particular on what they may teach us about the origin of matter and the possible existence of new forces that were important at earlier times in the evolution of the cosmos. I will also comment on how they complement experiments at the high energy and astrophysical frontiers.