Manne Siegbahn
Manne Siegbahn was a Swedish physicist who was awarded the Nobel Prize in Physics in 1924 for discoveries within X-ray spectroscopy.
The Memorial Lecture presents recent breakthroughs and developments in experimental physics. The lecture series was instituted in 1993 to the memory of Manne Siegbahn, and it is supported by the Royal Swedish Academy of Sciences through its Nobel Institute for Physics.
Lectures
2024
The James Webb Space Telescope - Transformative Science
Speaker: Gillian Wright (Royal Observatory Edinburgh)
Abstract: The much awaited James Webb Space Telescope (JWST) was launched on Christmas Day 2021. More than 20 years in development it defines the pinnacle of modern astronomical engineering achievement and a step change in observational capabilities. JWST is designed to peer across the universe, capturing images and data from the formation of the earliest galaxies to the atmospheres of planets, within and beyond our solar system. The engineering challenges and development of the mission will be described, including the European participation and the collaboration that designed and built MIRI, one of the four key instruments. After a flawless launch, the observatory is now used by the worldwide community, changing our understanding in many areas of astrophysics. Exciting early discoveries from the formation of stars and planets to how galaxies form and evolve will be described, along with the wonderful images that are transforming our view of the universe.
2023
Imaging Supermassive Black Holes: From Still Images to Video
Speaker: Sheperd Doeleman (Harvard University)
Abstract: Until recently, no one had ever seen what a black hole actually looked like. Einstein's theories predict that a distant observer should see a ring of light encircling the black hole, which forms when radiation emitted by infalling hot gas is lensed by the extreme gravity near the event horizon. The Event Horizon Telescope (EHT) is a global array of radio dishes, linked together by a network of atomic clocks to form an Earth-sized virtual telescope that can resolve the nearest supermassive black holes where this ring feature may be measured. On April 10th, 2019, the EHT project reported success: through observations of the supermassive black hole at the center of galaxy M87, we have seen the predicted strong gravitational lensing that matches the theory of General Relativity (GR). In 2022, observations of SgrA*, the black hole at the center of our Milky Way galaxy, revealed a similar ring with dimensions predicted by GR. These results have now opened the door to precision measurement of black holes on horizon scales, and next-generation enhancements to the array allow us to anticipate black hole movies by the end of this decade.
This talk will cover how this was accomplished, the impact, and what the future holds for the study of black holes.
2022
First Results and Recent Progress from the Muon g-2 Experiment at Fermilab’s Muon Campus
Speaker: Chris Polly (Fermilab)
Abstract: The much anticipated initial results from the Muon g-2 experiment at Fermilab’s Muon Campus were released last year. The new determination of the muon’s anomalous magnetic moment is in good agreement with the intriguing value obtained at Brookhaven National Laboratory 20 years ago, and has led to renewed interest due to the increased tension with the Standard Model prediction. The Muon Campus at Fermilab is a new accelerator facility capable of delivering the intense beams of muons required for the Muon g-2 and Mu2e experiments. This talk will discuss the Muon Campus physics program with an emphasis on the recent Muon g-2 results.
2020
Quantum experiments with mechanical motion of solids
Speaker: Cindy Regal (University of Colorado)
Abstract: Over the last decades, quantum effects in vibrations of micromechanical resonators have been observed in a surprising range of experiments. Achieving the quantum regime with tangible motion of solid objects has both piqued the curiosity of physicists, and enabled new approaches to difficult tasks in manipulating quantum information. I will present experiments in our group that measure the motion of micromachined drums, and discuss how they evolved from a rich history of read-out and control in quantum optics and precision measurement. I will highlight our current efforts to use mechanical motion as a link between quantum states in disparate parts of the electromagnetic spectrum.
2019
Science Highlights from the Nuclear Spectroscopic Telescope Array (NuSTAR): Bringing the High Energy Universe into Focus
Speaker: Fiona Harrison (Caltech)
Abstract: The Nuclear Spectroscopic Telescope Array, the first focusing high-energy X-ray (3 – 79 keV) telescope in orbit, extends sensitive X-ray observations above the band pass where Chandra and XMM-Newton operate. With an unprecedented combination of sensitivity, spectral and imaging resolution above 10 keV, NuSTAR is advancing our understanding of black holes, neutron stars, and supernova remnants. I will describe the mission, and present science highlights.
2018
Integral field spectroscopy and the exploration of the high redshift Universe
Speaker: Roland Bacon (Observatoire de Lyon)
Abstract: The first part of the lecture will be devoted to the development of integral field spectroscopy, from the historical development to the 3rd generation with MUSE. In the second part I will present some of the results brought by MUSE in the field of galaxy evolution and formation at high redshift. In the last part I will present some ideas for the future of integral field spectroscopy.
2017
Metamaterials
Speaker: David Smith (Duke University)
2016
Searching for – and finding! gravitational waves
Speaker: Gabriela Gonzalez (Louisiana State University, for the LIGO Scientific Collaboration and the Virgo Collaboration)
Abstract: On September 14 2015, the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a nearly simultaneous signal with time-frequency properties consistent with gravitational-wave emission by the merger of two massive compact objects. Further analysis of the signals by the LIGO Scientific Collaboration and the Virgo Collaboration revealed that the gravitational waves detected by LIGO came from the merger of a binary black hole (BBH) system. This observation, followed by another one in December 2015, marked the beginning of gravitational wave astronomy. I will describe some details of the observation, the status of LIGO and Virgo ground-based interferometric detectors, and prospects for future observations.
2015
Quantum Teleportation, Entanglement, and Einstein’s Question “What is Light?”
Speaker: Anton Zeilinger (University of Vienna)
Abstract: Einstein received the 1922 Nobel Prize for his groundbreaking idea of 1905 that light consists of particles, today called photons. Together with Podolsky and Rosen, he proposed in 1935 that two quantum systems can be connected in a way that is much stronger than in classical physics. The Austrian Nobel Prize winner Erwin Schrödinger coined the name “entanglement” and called it “the essential feature of quantum mechanics”. By Einstein, it was dismissed as “spooky action at a distance”. Due to the enormous experimental progress today, not only the old predictions were confirmed, but novel phenomena were discovered, including, for example, multi-particle entanglement and quantum teleportation.
These are not just intellectual curiosities, but they lay the foundation for a possible future information technology, with applications such as quantum communication, quantum cryptography and quantum computation. In the talk, some of the most recent experimental results, particularly on long-distance quantum communication and on the implementation of quantum states in higher-dimensional Hilbert spaces, will be presented and future possible applications will be discussed. These will, for example, include experiments using satellite-based quantum communication on a world-wide scale. It would be interesting to hear Albert Einstein’s reaction to these developments, particularly in view of his statement towards the end of his life that despite years of conscious brooding, he did not come closer to answering the question “What is light?”
2014
Exploring the gamma ray universe
Speaker: Bill Atwood (University of California, Santa Cruz)
Abstract: The Gamma ray Large Area Space Telescope (GLAST) project began in 1992, a year after the launch of EGRET onboard the CGRO spacecraft. Capitalizing on the advances in particle detector technology, the GLAST project developed an observatory, which would extend the discovery space of EGRET by over an order of magnitude. After its launch in 2008, GLAST was renamed Fermi-LAT and has performed an all-sky survey of the gamma ray sky ever since.
This talk will present details of how the instrument was designed and how the design choices contributed to the success of this mission. Highlights from the first 6 years of the Fermi-LAT mission will be presented.
2013
Higgs boson: foundations and implications of a very special discovery
Speaker: Fabiola Gianotti and Joseph Incandela (CERN (FG) and University of California, Santa Barbara/CERN (JI) )
Abstract: On 4 July 2012, the ATLAS and CMS experiments operating at the CERN Large Hadron Collider announced the discovery of a new particle compatible with the Higgs boson, which is a crucial piece for our understanding of fundamental physics and thus the structure and evolution of the universe.
This Lecture describes the unprecedented instruments and challenges that have allowed such an accomplishment, the physics meaning and relevance of this discovery, and the present understanding of the properties of this very special particle.
2012
Spin Excitation Spectroscopy – A Tool Set for Atomic-Scale Spin Systems
Speaker: Donald M. Eigler (The Wetnose Institute for Advanced Pelagic Studies)
Abstract: How can we rationally engineer atomic-scale spin systems that perform classical or quantum computation using only the spin degree of freedom? The first step along this road requires the ability to measure the behavior of spins at the single-atom and nanometer scale.
In this talk I will describe the development of Spin Excitation Spectroscopy, a tool set for measuring the energetics and dynamics of spins at the atomic scale with the Scanning Tunneling Microscope (STM). By combining Spin Excitation Spectroscopy with the imaging and manipulation of abilities of the STM, we are beginning to engineer computational functionality into small spin systems.
2010
The discovery of the first transiting Earth-like planet by the CoRoT satellite
Speaker: Daniel Rouan (LESIA, Observatoire de Paris-Meudon, France )
Abstract: In 2008, the photometric monitoring during 5 months by the French-European satellite CoRoT of thousands of stars, revealed for one of them 176 very shallow (ΔF/F = 3x10-4) but significant periodic decreases of brightness, every 0.854 day, with a duration of 1.3 h each. If the possible interpretation of those events as partial eclipses of the target, a solar-like star, by a transiting planet was correct, the planet should have a radius as small as 1.7 REarth, making it the smallest transiting planet discovered to date.
However, before publishing such an outstanding result, the team had to accomplish a thorough task of complementary observations from ground to assess this interpretation. Indeed, several alternative interpretations were possible, such as a background system of mutually eclipsing stars. Many techniques were used, on several among the most powerful telescopes: high resolution visible and infrared spectroscopy, on/off transit photometric observations, high resolution imaging with adaptive optics, colours of the transit, etc. None of them succeeded in invalidating the small planet hypothesis and the announcement of the discovery of Corot-7b was released in February 2009.
A firm confirmation came a few months later with the analysis of a long series of radial velocity measurements using HARPS, the best instrument in the world in this respect. The planet was there in the data, with a firm evaluation of its mass: 4.8 MEarth. The derived density, precisely equal to the Earth one, suggests a similar type - a rocky one - and a similar composition, dominated by silicates. In addition, it was shown that a second planet, of only twice the mass of the first one was present on a slightly larger orbit, but still extremely close from the star.
The discovery of the Corot-7 system is obviously an important milestone on the pathway to habitable planets and I will discuss several questions that have been worked out since then: Is there a third planet? What is the structure of Corot-7b? Its physical conditions? Are there clues on its formation? Etc.
2009
Experiments on the beta decay of highly-ionized atoms with challenging and puzzling results
Speaker: Fritz Bosch (GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany )
Abstract: Beta decay of highly-ionized atoms plays a significant role in stellar nucleosynthesis at temperatures of about 30 keV (s-process) where most nuclei are in a high atomic charge state. The facility at GSI, Darmstadt, providing both unstable highly-charged nuclides and an ion storage-cooler ring (ESR) to preserve their high charge state over a long time (hours) was and still is the only place addressing this field which is interesting for nuclear physics as well as for astrophysics.
During the last decade, the focus was on the investigation of two-body beta decays, i.e. bound-state beta decay and orbital electron capture (EC), where monochromatic (anti)neutrinos in the electron-flavour eigenstate are created. In course of the first measurements of the EC decay probability of few-electron ions it turned out that hydrogen-like 140Pr58+ and 142Pm60+ nuclides decay by about 50% faster than the helium-like ions, and even faster than the corresponding neutral atoms.
This result, although somewhat surprising, can be fully understood in the framework of standard nuclear physics. A few years ago, a new technique, single-ion decay spectroscopy has been developed at the ESR. Here, the number of stored ions is reduced to less than four and the "fate" of each single stored ion is observed continuously and time-resolved. On top of the expected exponentially decreasing EC decay probability, for both hydrogen-like 140Pr and 142Pm ions, periodic modulations were found with a period of about 7s and relative amplitude of 0.2. Tentatively, we argued that these oscillations could be due - as a special kind of "quantum beats"- to the coherent superposition of (at least) two mass eigenstates of the generated electron-neutrino which is a flavour eigenstate, but neither an energy- nor momentum eigenstate.
This very controversially discussed hypothesis predicts that similar modulations should also appear in other two-body beta decays with a period being proportional to the mass of the parent ion. To corroborate or disprove this hypothesis, some months ago an experiment with hydrogen-like 122I ions has been conducted, where a modulation period of about 6s is expected, supposed this "neutrino hypothesis" holds true. First results will be reported.
2008
Is the Search for the Origin of the Highest-Energy Cosmic Rays Over?
Speaker: Alan Watson (University of Leeds, United Kingdom )
Abstract: The reasons for studying the highest energy cosmic rays will be outlined together with a description of the Pierre Auger Observatory, now in full operation. The question posed in the title can now be asked only because of two results obtained using data recorded at the Observatory.
Firstly, it has been established that the flux of the highest energy cosmic rays is suppressed at energies beyond 5 x 1019 eV.
Secondly, above this energy anisotropy in the arrival directions of the particles has been discovered that appears to be associated with sources lying within 75 Mpc.
From these two observations it seems probable that we have observed the long-sought Greisen-Zatsepin-Kuz’min effect, demonstrating that ultra-high energy cosmic rays are of extragalactic origin. It is also probable that these particles are protons, thus offering the possibility of insights into features of particle physics at centre-of-mass energies 30 times greater than will be reached at the LHC.
Preliminary conclusions from studies of detailed features of extensive air showers suggest that extrapolations from Tevatron energies may not be what have been anticipated hitherto. Much further work remains to be done and the next steps will be outlined.
2007
Topological Transitions and Singularities in Fluids: The Life and Death of a Drop
Speaker: Sidney R. Nagel (University of Chicago, U.S.A. )
Abstract: The exhilarating spray from waves crashing into the shore, the distressing sound of a faucet leaking in the night, and the indispensable role of bubbles dissolving gas into the oceans are but a few examples of the ubiquitous presence and profound importance of drop formation and splashing in our lives. They are also examples of a liquid changing its topology.
Although part of our common everyday experience, these transitions are far from understood and reveal delightful and profound surprises upon careful investigation. For example in droplet fission, the fluid forms a neck that becomes vanishingly thin at the point of breakup. This topological transition is thus accompanied by a dynamic singularity in which physical properties such as pressure diverge. Singularities of this sort often organize the overall dynamical evolution of nonlinear systems.
I will first discuss the role of singularities in the breakup of drops. I will then discuss the fate of the drop when it falls and eventually splashes against a solid surface.
2006
Attosecond Physics
Speaker: Ferenc Krausz (Max-Planck-Institut für Quantenoptik, Garching, Germany; Ludwig-Maximilians-Universität, München, Germany; Technische Universität Wien, Austria )
Abstract: Fundamental processes in atoms, molecules, as well as condensed matter are triggered or mediated by the motion of electrons inside or between atoms. Electronic dynamics on atomic length scales tends to unfold within tens to thousands of attoseconds (1 attosecond [as] = 10-18 s).
Recent breakthroughs in laser science are now opening the door to watching and controlling these hitherto inaccessible microscopic dynamics. The key to accessing the attosecond time domain is the control of the electric field of (visible) light, which varies its strength and direction within less than a femtosecond (1 femtosecond = 1000 attoseconds).
Atoms exposed to a few oscillations cycles of intense laser light are able to emit a single extreme ultraviolet (xuv) burst lasting less than one femtosecond [1,2]. Full control of the evolution of the electromagnetic field in laser pulses comprising a few wave cycles [3] have recently allowed the reproducible generation and measurement of isolated 250-attosecond xuv pulses [4], constituting the shortest reproducible events and fastest measurement to date.
These tools have enabled us to visualize the oscillating electric field of visible light with an attosecond “oscilloscope” [5] as well as steering and real-time observation of the motion of electrons in atoms [6] and molecules [7]. Recent experiments [8] hold promise for the development of an attosecond x-ray source, which may pave the way towards 4D electron imaging with sub-atomic resolution in space and time.
[1] M. Hentschel et al., Nature 414, 509 (2001);
[2] R. Kienberger et al., Science 291, 1923 (2002);
[3] A. Baltuska et al., Nature 421, 611 (2003);
[4] R. Kienberger et al., Nature 427, 817 (2004);
[5] E. Goulielmakis et al., Science 305, 1267 (2004);
[6] M. Drescher et al., Nature 419, 803 (2002).
[7] J. Seres et al, Nature 433, 596 (2005)¸
[8] M. Kling et al., Science 312, 246 (2006).
2005
Neutrino and Astro-Physics Measurements with the Sudbury Neutrino Observatory
Speaker: Arthur B. McDonald (Queen's University, Kingston, Ontario, Canada )
Abstract: The Sudbury Neutrino Observatory (SNO) is a 1,000 tonne heavy-water-based neutrino detector in an ultra-clean environment created 2 km underground in a mine near Sudbury, Canada. Past measurements of solar neutrino fluxes have been smaller than predicted by solar model calculations, implying that the calculations are incomplete or that some of the electron neutrinos produced in the Sun change to another flavor en route to earth.
SNO has used neutrinos from 8B decay in the Sun to observe one neutrino reaction sensitive only to solar electron neutrinos and others sensitive to all active neutrino flavors and has found clear evidence for neutrino flavor change. This requires modification of the Standard Model for elementary particles and confirms solar model calculations with great accuracy.
Results from the multi-year SNO observation program will be presented, including details of the broad calibration program, extensive control and measurement of radioactive backgrounds and use of salt in the heavy water to enhance sensitivity to all active neutrino flavors.
The implications of the SNO results and other recent neutrino results for particle physics and solar physics will be discussed. The expansion of the underground facility to create a long-term international laboratory (SNOLAB) with a broad future experimental capability will also be described.
Towards a Solid State Quantum Information Processor: Manipulation and Control of the Quantum State of an Electrical Circuit
Speaker: Michel H. Devoret (Department of Applied Physics, Yale University, New Haven, U.S.A.)
Abstract: Could the bits of a computer be atom-like entities behaving quantum-mechanically? The miniaturization of transistors and Boolean gates down to single atoms or electrons has been explored as early as the 1980's, but it is only in the last decade that the superiority, for certain class of problems, of the quantum computer over its conventional classical counterpart has been fully understood theoretically.
This discovery has spurred a flurry of activity aimed at implementing practically a "quantum machine" which would compute. In our own laboratory, we have followed the lead of superconducting integrated circuits, whose fabrication directly benefits from a whole body of knowledge in micro- and nano-technology developed for semiconducting devices.
The problem with solid-state implementations of "qubits" is their potentially strong coupling to unwanted degrees of freedom in the various materials of the circuit. Yet, we have shown experimentally that for a particular superconducting tunnel junction circuit ? the so-called "quantronium"? electrical symmetries could be exploited to suppress, to a large extent, this undesirable coupling [1].
In the last few years, recent advances in Europe, Japan and the US have propelled the quantum mechanical coherence of superconducting circuits at a stage where genuine quantum information processing involving a register of several qubits can be engineered.
[1] D. Vion et al., Science 296 (2002) 286
2004
A Massive Accreting Black Hole at the Center of the Milky Way!
Speaker: Andreas Eckart (Physikalisches Institut, Universität zu Köln, Köln, Germany )
Abstract: At a distance of only ~26400 light years the Galactic center is the closest 'quiescent' galaxy nucleus that we can now study in unprecedented detail. Over more than 10 years proper motions and orbits of individual stars in the central stellar cluster have been observed using speckle and adaptive optics techniques at the ESO NTT and the VLT.
Recently the unique equipment in combination with the advantages of the ESO Paranal site (excellent seeing, GC passes close to Zenith), make the VLT the ideal instrument for studying the extremely dense GC stellar cluster and the immediate environment of the compact radio source SagittariusA* (SgrA*) at ist center.
Observations of the orbit of star S2 have provided new, highly significant evidence that the central non-thermal radio source SgrA* is indeed a super-massive black hole with a mass of 3-4 million solar masses. The recent detection of quiescent emission and powerful flare activity of SgrA* in the X-ray and near-infrared domain have strengthened the case for an accreting massive black hole even further.
2002
Light at Bicycle Speed ... and Slower Yet!
Speaker: Lene Vestergaard Hau (Lyman Laboratory, Harvard University, Cambridge, U.S.A. )
Abstract: Light pulses have been slowed in a Bose-Einstein condensate to only 17 m/s, more than seven orders of magnitude lower than the light speed in vacuum. Associated with the dramatic reduction factor for the light speed is a spatial compression of the pulses by the same large factor. A light pulse, which is 1-2 miles long in vacuum, is compressed to a size of ~50 um, and at that point it is completely contained within the atom cloud.
This further allows the light pulse to be completely stopped and stored in the atomic medium for up to several milliseconds, and subsequently regenerated with no loss. With the most recent extension of the method, the light roadblock, light pulses have been compressed from 2 miles to only 1-2 um. This system has been used to generate the superfluid analogue of shock waves, Quantum Shock Waves, in Bose-Einstein condensates.
These dramatic excitations result in the formation of solitons that in turn decay into quantized vortices - created far out of equilibrium, in pairs of opposite circulation - revealing directly the process of superfluid breakdown in Bose-Einstein condensates.
Imaging the Embryonic Universe: First Resolved Images of the Cosmic Microwave Background
Speaker: Andrew E. Lange (Department of Astronomy, California Institute of Technology (Caltech), Pasadena, California, U.S.A. )
Abstract: The primeval fireball that accompanied the Big Bang is still visible today as a faint microwave glow that fills the sky. This Cosmic Microwave Background (CMB) provides a snapshot of the universe at an age of ~ 0.5 Myr, equivalent to imaging a human being a few hours after conception.
The details of the faint structures visible in the nearly isotropic CMB reveal much about the structure and evolution of the universe. The first resolved images of the CMB were obtained by BOOMERANG, a balloon-borne microwave telescope that circumnavigated the Antarctic.
The BOOMERANG images reveal a universe that is composed of 5% baryonic matter, 30 % non-relativistic dark matter of unknown form, and 65% "dark energy" that is currently causing the expansion of the universe to accelerate.
2000
Seeing a Single Photon without Destroying it and Manipulating Entanglement in Atom-Cavity Experiments
Speaker: Serge Haroche (Ecole Normale Supérieure, Paris, France )
Abstract: Light detection is usually a destructive process, in that detectors annihilate photons and convert them into electrical signals, making it impossible to see a single photon twice. But this limitation is not fundamental — quantum non-demolition strategies permit repeated measurements of physically observable quantities, yielding identical results.
The non-destructive measurement of a single photon requires an extremely strong matter-radiation coupling. This can be realized in cavity quantum electrodynamics, where the strength of the interaction between an atom and a photon can overwhelm all dissipative couplings to the environment.
In the experiments reported, an atomic interferometer has been used to measure the phase shift in an atomic wavefunction, caused by a cycle of photon absorption and emission.
The method amounts to a restricted quantum non-demolition measurement, which can be applied only to states containing one or zero photons. It may lead to quantum logic gates based on cavity quantum electrodynamics, and multi-atom entanglement.
1999
The Long Way to the Island of Stability of Superheavy Elements Close to Z=114
Speaker: Yuri Oganessian (Joint Institute for Nuclear Research (JINR), Dubna, Russia)
Abstract: The talk will present and discuss the results of experiments aimed at testing the fundamental predictions of the modern theory on the existence of "islands of stability" of super heavy elements.
The talk will include:
- theoretical concepts of the properties of nuclear matter. The influence of nuclear structure on the limits of the existence of elements
- fusion of massive nuclei for the synthesis of heavy elements
- experimental techniques for the synthesis and study of the properties of new elements
- first nuclides on the "island of stability"
- perspectives.
1998
The Prospects for the Detection of Gravitational Waves
Speaker: Rainer Weiss (Massachusetts Institute of Technology, Cambridge, U.S.A. )
Abstract: The talk describes the world wide effort to detect gravitational waves from astrophysical sources by long baseline laser interferometry. Projects in Europe, the United States of America, Japan and Australia hope to be operating within the coming decade.
The talk includes:
- the concept of the detectors and prototypes,
- the noise limits to the sensitivity,
- a review of the known and posited astrophysical sources,
- some details of the LIGO (Laser Interferometer Gravitational-wave Observatory),
- the techniques to give confidence to a detection.
1997
Elementary Particles from the Z to the Higgs. Loops, tides and trains
Speaker: Alain Blondel (LPNHE, Ecole Polytechnique, Paris, France )
Abstract: During 8 years of operation of the LEP accelerator in Geneva, the properties of the Z boson have been measured with extreme precision.
The structure of the Standard Model of elementary particles and their interactions has been verified. Furthermore, quantum tunnel effects make these precise measurements sensitive to the existence and mass of yet unknown particles - in particular the mysterious Higgs boson.
Real perturbations, induced on the 27-km long accelerator by the moon, the trains and the sun make sure that physicists remain on planet earth.
1996
Discovery of Planets Orbiting Sun-Like Stars
Speaker: Geoffrey W. Marcy (San Francisco State University and University of California, Berkeley, California, U.S.A. )
Abstract: During the past 12 months, astronomers have finally discovered planets orbiting Sun-like stars. All were discovered by precise Doppler measurements of the host stars. Some of these planets have properties similar to the nine planets in our own Solar System. But many of the planets have properties that are totally unexpected.
Several of the planets are more massive than even Jupiter and some orbit their host star in very small orbits, smaller than Mercury's orbit. Equally unexpected is that two of these "planets" have non-circular orbits.
Current theory of the formation of planetary systems is suddenly challenged to account for these new planetary properties. The character of the new worlds spawns many questions about the uniqueness of our Solar System and the prevalence of Earth-like planets.
These questions are now being addressed with the Keck 10-meter telescope, which will hunt for Saturn-like and Neptune-like planets.
Bose-Einstein Condensation in a Dilute Atomic Vapor
Speaker: Eric Cornell (J.I.L.A., University of Colorado and the National Institute for Standards and Technology, Boulder, Colorado, U.S.A. )
Abstract: Advances in optical and magnetic cooling and trapping of atoms have made possible the creation of a Bose-Einstein condensate in dilute atomic vapors at temperatures around 100 nK.
The range of experimental techniques available for making sensitive measurements in atomic gases is quite distinct from (and complementary to) those currently used in superfluid liquid helium. From a theoretical point of view, the interactions between the atoms are weak enough that calculations can be performed in the framework of perturbation theory.
Thus Bose condensed atomic vapors are an ideal environment for studying many novel aspects of quantum degeneracy.
The lecture will review previous efforts to reach Bose condensation, describe the techniques which have recently been successful, and discuss some of the possible directions for future scientific exploration in this area.
1995
Quantum Engineering of Nanostructures. Novel Physics and New Concepts for Electronic Devices
Speaker: Hiroyuki Sasaki (Research Center for Advanced Science and Technology, University of Tokyo, Japan )
Abstract: The remarkable progress in semiconductor technology has allowed us to form various ultrathin layered structures with feature sizes of 10-30 nm. In such systems, electrons are quantum mechanically confined to form a series of standing wave states fi(z) with discrete energies Ez(i), while their in-plane motion remains free. Indeed, such a two dimensional (2-D) electron gas plays now very important roles both in solid-state physics and electronics.
Although the 2-D electron system is still a fertile field, there are vast fields of nanostructures, where new classes of phenomena are being disclosed and exploited. In this lecture, we review and discuss such studies.
First we describe various attempts, by which the tunnel escape process of electrons through the barrier layer is quantum mechanically controlled; we examine how they can be used in realizing such devices as intersubband infrared detectors, ultrafast resonant tunnelling diodes, and quantum-beat oscillators.
Second, we review a series of work to confine electrons in quantum-wire and/or quantum dot strucutres and discuss what kind of unique properties or functions have been and will be found in such 1-D and 0-D systems. We examin the current status of nanotechnology by which 10-nm scale wires and dots are formed.
1994
GALLEX Solar Neutrino Results and their Implications
Speaker: Till Kirsten (Max-Planck-Institute, Heidelberg, Germany )
Abstract: Solar neutrino deTill Kirsten (Max-Planck-Institute, Heidelberg, Germany )tection can probe the state of the solar interior. The flux of pp-neutrinos (from hydrogen fusion: p+p->d+e++ve) is firmly predicted from the solar luminosity, any shortage would indicate restmass-mediated ve-disappearance during transit between the solar core and the detector.
The expected fluxes of the less abundant but higher energy neutrinos from 8B and 7Be are more sensitive to the details of the solar model. For them the observation of a deficit may indicate either incomplete understanding of the stellar interior or new physics through massive neutrinos. The low-threshold gallium detector operated by the GALLEX collaboration1 in the Gran Sasso undergound laboratory (Italy) is sensitive to pp-neutrinos. It succeeded in their detection.
For this, techniques were developed to routinely extract and detect a few radioactive 71Ge atoms from a 100 ton target. This first observation of hydrogen fusion inside a start transfers solar models since Eddington from the realm of theory into the sphere of observational facts.
The GALLEX result can accommodate the expected pp-neutrinos at full strength. Hence, massive neutrinos are not enforced. At the same time, GALLEX confirms a shortage of the higher energy neutrinos, consistent with the results of the Homestake and Kamiokande experiments. 1MPI Heidelberg; KFK Karlsruhe; LNGS L'Aquila (Gran Sasso); Università di Milano; TUM München; Observatoire de Nice; WIS Rehovot; Università di Roma; CE Saclay; BNL, Upton, N.Y.
1993
One Antiproton Radio: Precision Comparisons of a Single Trapped Antiproton and Proton
Speaker: Gerald Gabrielse (Physics Dept., Harvard University, U.S.A. )
Abstract: During the last several years, our TRAP collaboration at LEAR, CERN, has pioneered techniques for slowing, trapping, cooling and indefinitely storing antiprotons to energies more than 1010 times lower than previously possible.
The initial comparison of the cyclotron frequencies of antiprotons and protons resulted in a 1000-fold improvement over previous relative mass comparisons. The radio signal from a single trapped antiproton is now being used for precision measurements. An additional 50-fold improvement in the antiproton to proton mass ratio is expected soon. Many cold antiprotons are "stacked" as another important step toward the eventual production of antihydrogen. Sufficient amounts of positrons have been trapped in vacuum in pursuit of the same goal. The proton-antiproton mass ratio and studies of antihydrogen offer checks of CPT for strongly and electromagnetically interacting particles, respectively.