Science.gov

Sample records for a-z atomic physics

  1. Atomic physics

    SciTech Connect

    Livingston, A.E.; Kukla, K.; Cheng, S.

    1995-08-01

    In a collaboration with the Atomic Physics group at Argonne and the University of Toledo, the Atomic Physics group at the University of Notre Dame is measuring the fine structure transition energies in highly-charged lithium-like and helium-like ions using beam-foil spectroscopy. Precise measurements of 2s-2p transition energies in simple (few-electron) atomic systems provide stringent tests of several classes of current atomic- structure calculations. Analyses of measurements in helium-like Ar{sup 16+} have been completed, and the results submitted for publication. A current goal is to measure the 1s2s{sup 3}S{sub 1} - 1s2p{sup 3}P{sub 0} transition wavelength in helium-like Ni{sup 26+}. Measurements of the 1s2s{sup 2}S{sub 1/2} - 1s2p{sup 2}P{sub 1/2,3/2} transition wavelengths in lithium-like Kr{sup 33+} is planned. Wavelength and lifetime measurements in copper-like U{sup 63+} are also expected to be initiated. The group is also participating in measurements of forbidden transitions in helium-like ions. A measurement of the lifetime of the 1s2s{sup 3}S{sub 1} state in Kr{sup 34+} was published recently. In a collaboration including P. Mokler of GSI, Darmstadt, measurements have been made of the spectral distribution of the 2E1 decay continuum in helium-like Kr{sup 34+}. Initial results have been reported and further measurements are planned.

  2. Atomic and Molecular Physics

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K.

    2005-01-01

    A symposium on atomic and molecular physics was held on November 18, 2005 at Goddard Space Flight Center. There were a number of talks through the day on various topics such as threshold law of ionization, scattering of electrons from atoms and molecules, muonic physics, positron physics, Rydberg states etc. The conference was attended by a number of physicists from all over the world.

  3. Advances in atomic physics

    PubMed Central

    El-Sherbini, Tharwat M.

    2013-01-01

    In this review article, important developments in the field of atomic physics are highlighted and linked to research works the author was involved in himself as a leader of the Cairo University – Atomic Physics Group. Starting from the late 1960s – when the author first engaged in research – an overview is provided of the milestones in the fascinating landscape of atomic physics. PMID:26425356

  4. PHYSICS: Toward Atom Chips.

    PubMed

    Fortágh, József; Zimmermann, Claus

    2005-02-11

    As a novel approach for turning the peculiar features of quantum mechanics into practical devices, researchers are investigating the use of ultracold atomic clouds above microchips. Such "atom chips" may find use as sensitive probes for gravity, acceleration, rotation, and tiny magnetic forces. In their Perspective, Fortagh and Zimmermann discuss recent advances toward creating atom chips, in which current-carrying conductors in the chips create magnetic microtraps that confine the atomic clouds. Despite some intrinsic limits to the performance of atom chips, existing technologies are capable of producing atom chips, and many possibilities for their construction remain to be explored.

  5. Contemporary Aspects of Atomic Physics

    ERIC Educational Resources Information Center

    Knott, R. G. A.

    1972-01-01

    The approach generally used in writing undergraduate textbooks on Atomic and Nuclear Physics presents this branch as historical in nature. Describes the concepts of astrophysics, plasma physics and spectroscopy as contemporary and intriguing for modern scientists. (PS)

  6. Contemporary Aspects of Atomic Physics

    ERIC Educational Resources Information Center

    Knott, R. G. A.

    1972-01-01

    The approach generally used in writing undergraduate textbooks on Atomic and Nuclear Physics presents this branch as historical in nature. Describes the concepts of astrophysics, plasma physics and spectroscopy as contemporary and intriguing for modern scientists. (PS)

  7. Atomic Collisions and Plasma Physics.

    DTIC Science & Technology

    1984-01-31

    AD-R141 320 ATOMIC COLLISIONS AND PLASMA PHYSICS(U) PITTSBURGH UNIV i/il PR DEPT OF PHYSICS AND ASTRONOMY M R BIONDI 3i JAN 84 RFGL-TR-94-044 Fi9628...OF STANDARDS t963 A % : C~44 h ’ I ATOMIC COLLISIONS AND PLASMA PHYSICS Manfred A. Biondi Department of Physics and Astronomy University of Pittsburgh... PLASMA PHYSICS Final - 11/1/80 - 12/31/83 6 PI kF%oMINC. OR. REPORT NUMA4I R 7. AUTHO R(j iS CONTRACTOR GRANT NUM8ER(. * Manfred A. Biondi Fl9628-81

  8. Supercomputers and atomic physics data

    SciTech Connect

    Abdallah, J. Jr.; Clark, R.E.H.

    1988-01-01

    The advent of the supercomputer has dramatically increased the possibilities for generating and using massive amounts of detailed fine structure atomic physics data. Size, speed, and software have made calculations which were impossible just a few years ago into a reality. Further technological advances make future possibilities seem endless. The cornerstone atomic structure codes of R.D. Cowan have been adapted into a single code CATS for use on Los Alamos supercomputers. We provide a brief overview of the problem; and report a sample CATS calculation using configuration interaction to calculate collision and oscillator strengths for over 300,000 transitions in neutral nitrogen. We also discuss future supercomputer needs. 2 refs.

  9. Transition state in atomic physics

    NASA Astrophysics Data System (ADS)

    Jaffé, Charles; Farrelly, David; Uzer, T.

    1999-11-01

    The transition state is fundamental to modern theories of reaction dynamics: essentially, the transition state is a structure in phase space that all reactive trajectories must cross. While transition-state theory (TST) has been used mainly in chemical physics, it is possible to apply the theory to considerable advantage in any collision problem that involves some form of reaction. Of special interest are systems in which chaotic scattering or half-scattering occurs such as the ionization of Rydberg atoms in external fields. In this paper the ionization dynamics of a hydrogen atom in crossed electric and magnetic fields are shown to possess a transition state: We compute the periodic orbit dividing surface (PODS) which is found not to be a dividing surface when projected into configuration space. Although the possibility of a PODS occurring in phase space rather than configuration space has been recognized before, to our knowledge this is the first actual example: its origin is traced directly to the presence of velocity-dependent terms in the Hamiltonian. Our findings establish TST as the method of choice for understanding ionization of Rydberg atoms in the presence of velocity-dependent forces. To demonstrate this TST is used to (i) uncover a multiple-scattering mechanism for ionization and (ii) compute ionization rates. In the process we also develop a method of computing surfaces of section that uses periodic orbits to define the surface, and examine the fractal nature of the dynamics.

  10. Bringing Atoms into First-Year Physics.

    ERIC Educational Resources Information Center

    Chabay, Ruth W.; Sherwood, Bruce A.

    1999-01-01

    Argues that thermal physics should not be treated as a separate topic in introductory physics. Provides an example of a course that emphasizes physical modeling of the phenomenon in terms of the atomic nature of matter. (Author/CCM)

  11. Bringing Atoms into First-Year Physics.

    ERIC Educational Resources Information Center

    Chabay, Ruth W.; Sherwood, Bruce A.

    1999-01-01

    Argues that thermal physics should not be treated as a separate topic in introductory physics. Provides an example of a course that emphasizes physical modeling of the phenomenon in terms of the atomic nature of matter. (Author/CCM)

  12. Reconstruction of a scanned topographic image distorted by the creep effect of a Z scanner in atomic force microscopy.

    PubMed

    Han, Cheolsu; Chung, Chung Choo

    2011-05-01

    We analyzed the illusory slopes of scanned images caused by the creep of a Z scanner in an atomic force microscope (AFM) operated in constant-force mode. A method to reconstruct a real topographic image using two scanned images was also developed. In atomic force microscopy, scanned images are distorted by undesirable effects such as creep, hysteresis of the Z scanner, and sample tilt. In contrast to other undesirable effects, the illusory slope that appears in the slow scanning direction of an AFM scan is highly related to the creep effect of the Z scanner. In the controller for a Z scanner, a position-sensitive detector is utilized to maintain a user-defined set-point or force between a tip and a sample surface. This serves to eliminate undesirable effects. The position-sensitive detector that detects the deflection of the cantilever is used to precisely measure the topography of a sample. In the conventional constant-force mode of an atomic force microscope, the amplitude of a control signal is used to construct a scanned image. However, the control signal contains not only the topography data of the sample, but also undesirable effects. Consequently, the scanned image includes the illusory slope due to the creep effect of the Z scanner. In an automatic scanning process, which requires fast scanning and high repeatability, an atomic force microscope must scan the sample surface immediately after a fast approach operation has been completed. As such, the scanned image is badly distorted by a rapid change in the early stages of the creep effect. In this paper, a new method to obtain the tilt angle of a sample and the creep factor of the Z scanner using only two scanned images with no special tools is proposed. The two scanned images can be obtained by scanning the same area of a sample in two different slow scanning directions. We can then reconstruct a real topographic image based on the scanned image, in which both the creep effect of the Z scanner and the slope

  13. Reconstruction of a scanned topographic image distorted by the creep effect of a Z scanner in atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Han, Cheolsu; Chung, Chung Choo

    2011-05-01

    We analyzed the illusory slopes of scanned images caused by the creep of a Z scanner in an atomic force microscope (AFM) operated in constant-force mode. A method to reconstruct a real topographic image using two scanned images was also developed. In atomic force microscopy, scanned images are distorted by undesirable effects such as creep, hysteresis of the Z scanner, and sample tilt. In contrast to other undesirable effects, the illusory slope that appears in the slow scanning direction of an AFM scan is highly related to the creep effect of the Z scanner. In the controller for a Z scanner, a position-sensitive detector is utilized to maintain a user-defined set-point or force between a tip and a sample surface. This serves to eliminate undesirable effects. The position-sensitive detector that detects the deflection of the cantilever is used to precisely measure the topography of a sample. In the conventional constant-force mode of an atomic force microscope, the amplitude of a control signal is used to construct a scanned image. However, the control signal contains not only the topography data of the sample, but also undesirable effects. Consequently, the scanned image includes the illusory slope due to the creep effect of the Z scanner. In an automatic scanning process, which requires fast scanning and high repeatability, an atomic force microscope must scan the sample surface immediately after a fast approach operation has been completed. As such, the scanned image is badly distorted by a rapid change in the early stages of the creep effect. In this paper, a new method to obtain the tilt angle of a sample and the creep factor of the Z scanner using only two scanned images with no special tools is proposed. The two scanned images can be obtained by scanning the same area of a sample in two different slow scanning directions. We can then reconstruct a real topographic image based on the scanned image, in which both the creep effect of the Z scanner and the slope

  14. Physics through the 1990s: Atomic, molecular and optical physics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The volume presents a program of research initiatives in atomic, molecular, and optical physics. The current state of atomic, molecular, and optical physics in the US is examined with respect to demographics, education patterns, applications, and the US economy. Recommendations are made for each field, with discussions of their histories and the relevance of the research to government agencies. The section on atomic physics includes atomic theory, structure, and dynamics; accelerator-based atomic physics; and large facilities. The section on molecular physics includes spectroscopy, scattering theory and experiment, and the dynamics of chemical reactions. The section on optical physics discusses lasers, laser spectroscopy, and quantum optics and coherence. A section elucidates interfaces between the three fields and astrophysics, condensed matter physics, surface science, plasma physics, atmospheric physics, and nuclear physics. Another section shows applications of the three fields in ultra-precise measurements, fusion, national security, materials, medicine, and other topics.

  15. Relativistic atomic physics at the SSC

    SciTech Connect

    1990-12-31

    This report discusses the following proposed work for relativistic atomic physics at the Superconducting Super Collider: Beam diagnostics; atomic physics research; staffing; education; budget information; statement concerning matching funds; description and justification of major items of equipment; statement of current and pending support; and assurance of compliance.

  16. Advances in atomic physics: Four decades of contribution of the Cairo University - Atomic Physics Group.

    PubMed

    El-Sherbini, Tharwat M

    2015-09-01

    In this review article, important developments in the field of atomic physics are highlighted and linked to research works the author was involved in himself as a leader of the Cairo University - Atomic Physics Group. Starting from the late 1960s - when the author first engaged in research - an overview is provided of the milestones in the fascinating landscape of atomic physics.

  17. Benchmarking Attosecond Physics with Atomic Hydrogen

    DTIC Science & Technology

    2015-05-25

    Final 3. DATES COVERED (From - To) 12 Mar 12 – 11 Mar 15 4. TITLE AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a...NOTES 14. ABSTRACT The research team obtained uniquely reliable reference data on atomic interactions with intense few-cycle laser pulses...AND SUBTITLE Benchmarking attosecond physics with atomic hydrogen 5a. CONTRACT NUMBER FA2386-12-1-4025 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

  18. Many-Body Atomic Physics

    NASA Astrophysics Data System (ADS)

    Boyle, J. J.; Pindzola, M. S.

    1998-09-01

    Preface; Contributors; Introduction; Part I. Atomic Structure: 1. Development of atomic many-body theory Ingvar Lindgren; 2. Relativistic MBPT for highly charged ions W. R. Johnson; 3. Parity nonconservation in atoms S. A. Blundell, W. R. Johnson, and J. Sapirstein; Part II. Photoionization of Atoms: 4. Single photoionization processes J. J. Boyle, and M. D. Kutzner; 5. Photoionization dominated by double excitation T. N. Chang; 6. Direct double photoionization in atoms Z. W. Liu; 7. Photoelectron angular distributions Steven T. Manson; Part III. A. Atomic Scattering - General Considerations: 8. The many-body approach to electron-atom collisions M. Ya Amusia; 9. Theoretical aspects of electron impact ionization P. L. Altick; Part III. B. Atomic Scattering - Low-Order Applications: 10. Perturbation series methods D. H. Madison; 11. Target dependence of the triply differential cross section Cheng Pan and Anthony F. Starace; 12. Overview of Thomas processes for fast mass transfer J. H. McGuire, Jack C. Straton and T. Ishihara; Part III. C. Atomic Scattering - All-Order Applications: 13. R-matrix Theory: Some Recent Applications Philip G. Burke: 14. Electron scattering: application of Dirac R-matrix theory Wasantha Wijesundera, Ian Grant and Patrick Norrington; 15. Close coupling and distorted-wave theory D. C. Griffin and M. S. Pindzola; Appendix: Units and notation; References; Index.

  19. Many-Body Atomic Physics

    NASA Astrophysics Data System (ADS)

    Boyle, J. J.; Pindzola, M. S.

    2005-11-01

    Preface; Contributors; Introduction; Part I. Atomic Structure: 1. Development of atomic many-body theory Ingvar Lindgren; 2. Relativistic MBPT for highly charged ions W. R. Johnson; 3. Parity nonconservation in atoms S. A. Blundell, W. R. Johnson, and J. Sapirstein; Part II. Photoionization of Atoms: 4. Single photoionization processes J. J. Boyle, and M. D. Kutzner; 5. Photoionization dominated by double excitation T. N. Chang; 6. Direct double photoionization in atoms Z. W. Liu; 7. Photoelectron angular distributions Steven T. Manson; Part III. A. Atomic Scattering - General Considerations: 8. The many-body approach to electron-atom collisions M. Ya Amusia; 9. Theoretical aspects of electron impact ionization P. L. Altick; Part III. B. Atomic Scattering - Low-Order Applications: 10. Perturbation series methods D. H. Madison; 11. Target dependence of the triply differential cross section Cheng Pan and Anthony F. Starace; 12. Overview of Thomas processes for fast mass transfer J. H. McGuire, Jack C. Straton and T. Ishihara; Part III. C. Atomic Scattering - All-Order Applications: 13. R-matrix Theory: Some Recent Applications Philip G. Burke: 14. Electron scattering: application of Dirac R-matrix theory Wasantha Wijesundera, Ian Grant and Patrick Norrington; 15. Close coupling and distorted-wave theory D. C. Griffin and M. S. Pindzola; Appendix: Units and notation; References; Index.

  20. Classical approach in atomic physics

    NASA Astrophysics Data System (ADS)

    Solov'ev, E. A.

    2011-12-01

    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincaré section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormgroup symmetry, criterion of accuracy and so on are reviewed as well.

  1. Atomic and Molecular Physics Program

    DTIC Science & Technology

    2013-03-05

    DESCRIPTION OF PORTFOLIO: Understanding interactions between atoms, molecules, ions, and radiation. SUB-AREAS IN PORTFOLIO: • Cold Quantum ...Gases − Strongly-interacting quantum gases − Ultracold molecules − New phases of matter − Non-equilibrium quantum dynamics • Quantum Information...Science (QIS) − Quantum simulation − Quantum communication − Quantum metrology, sensing, and imaging − Cavity optomechanics 3 DISTRIBUTION STATEMENT

  2. The atomic hypothesis: physical consequences

    NASA Astrophysics Data System (ADS)

    Rivas, Martín

    2008-08-01

    The hypothesis that matter is made of some ultimate and indivisible objects, together with the restricted relativity principle, establishes a constraint on the kind of variables we are allowed to use for the variational description of elementary particles. We consider that the atomic hypothesis not only states the indivisibility of elementary particles, but also that these ultimate objects, if not annihilated, cannot be modified by any interaction so that all allowed states of an elementary particle are only kinematical modifications of any one of them. Therefore, an elementary particle cannot have excited states. In this way, the kinematical group of spacetime symmetries not only defines the symmetries of the system, but also the variables in terms of which the mathematical description of the elementary particles can be expressed in either the classical or the quantum mechanical description. When considering the interaction of two Dirac particles, the atomic hypothesis restricts the interaction Lagrangian to a kind of minimal coupling interaction.

  3. Physical Limits on Atomic Resolution

    NASA Astrophysics Data System (ADS)

    van Dyck, D.; van Aert, S.; den Dekker, A. J.

    2004-02-01

    It is shown that the ultimate resolution is not limited by the bandwidth of the microscope but by the bandwidth (i.e., the scattering power) of the object. In the case of a crystal oriented along a zone axis, the scattering is enhanced by the channeling of the electrons. However, if the object is aperiodic along the beam direction, the bandwidth is much more reduced. A particular challenge are the amorphous objects. For amorphous materials, the natural bandwidth is that of the single atom and of the order of 1 [Angstrom capital A, ring][minus sign]1, which can be reached with the present generation of medium voltage microscopes without aberration correctors. A clear distinction is made between resolving a structure and refining, that is, between resolution and precision. In the case of an amorphous structure, the natural bandwidth also puts a limit on the number of atom coordinates that can be refined quantitatively. As a consequence, amorphous structures cannot be determined from one projection, but only by using atomic resolution tomography. Finally a theory of experiment design is presented that can be used to predict the optimal experimental setting or the best instrumental improvement. Using this approach it is suggested that the study of amorphous objects should be done at low accelerating voltage with correction of both spherical and chromatic aberration.

  4. The Atomic and Nuclear Physics of Atomic EDMs

    NASA Astrophysics Data System (ADS)

    Chupp, Timothy

    2016-09-01

    Atomic Electric-Dipole-Moment (EDM) measurements employ low-energy atomic and precision-measurement techniques to measure the effects of elementary particle forces that affect the distribution of charge and mass in the nucleus, which is probed by the atomic electrons. Experiments and their interpretation strongly overlap atomic and nuclear physics in the experimental and theoretical problems presented. On the experimental side, the atomic EDM couples to electric fields while the magnetic dipole moment couples to magnetic fields requiring exquisite control and characerization of the magnetic fields. Measuring the tiny frequency shifts requires clock-comparisons and a large signal-to-noise ratio for frequency resolution much smaller than the linewidths, which are lmitied by observation times. To address the experimental challenges, I will discuss systematic effects related to magnetic fields and techniques of magnetometry and co-magntometery as well as optical pumping and related techniques that enhance signal-to-noise. I will also address the interpretation of atomic EDMs in terms of a set of low-energy parameters that relate to effective-field-theory coefficients, and I will empshaize the need for improved calculations from both atomic-theory and nuclear theory.

  5. 3He: cosmological and atomic physics experiments.

    PubMed

    Bunkov, Yuriy M

    2008-08-28

    Because the superfluid 3He order parameter exhibits many similarities with that of our Universe, the superfluid condensate may be considered as a quantum vacuum that carries various types of quasiparticles and topological defects. The condensate thus provides a test system for the experimental investigation of many general physics problems in cosmology, atomic or nuclear physics that are otherwise difficult or even impossible to investigate experimentally.

  6. Atomic and molecular physics at LURE

    SciTech Connect

    Morin, P. |

    1994-08-01

    A short overview of the present research activity at LURE is given, in the field of atomic and molecular physics. Three selected examples are discussed in more detail and the {open_quotes}SOLEIL{close_quotes} project of a new French synchrotron facility is presented.

  7. (Atomic collisions in solid and plasma physics)

    SciTech Connect

    Robinson, M.T.

    1989-09-05

    The author visited the Max-Planck-Institut for Plasma Physics, Garching, FRG, to continue collaborative research activities in the area of sputtering and plasma-wall interactions. He then attended the Thirteenth International Conference on Atomic Collisions in Solids, where he presented a paper on recent research at ORNL. A few remarks about cold fusion'' are appended.

  8. Atomic, molecular and optical physics at Bethel

    NASA Astrophysics Data System (ADS)

    Hoyt, Chad; Klemme, Dan

    2012-02-01

    An example of the close connection between research and advanced labs at Bethel University is the recent realization of cold lithium atoms in a magneto-optical trap (MOT). Several aspects of the cooling and trapping research took root in the laboratory components of the Optics and Lasers upper-level courses. These included a wavelength meter with sub-picometer accuracy and precision, stabilized laser diodes and molecular and atomic spectroscopy. Work on the MOT began in 2008 and has involved students (a total of 12, including several post-General Physics sophomores) working during summers, course projects and senior research. Lithium MOTs offer challenges (e.g. low vapor pressure) and advantages in an undergraduate lab with respect to the more common rubidium systems. Lasers for lithium are at 671 nm, a more practical red color that can still take advantage of inexpensive laser diodes and broadband optical coatings. Its relatively simple atomic structure makes lithium amenable for stringent comparisons between theory and experiment. Recent high precision absolute frequency measurements using an atomic beam disagree. Cold-atom spectroscopy of lithium could help resolve questions about the atomic structure of lithium.

  9. Atomic physics processes in radial transport calculations

    SciTech Connect

    Hogan, J.T.

    1983-02-01

    These lectures were intended as preparation for detailed discussions of the role of atomic and molecular physics in confinement research at the 1982 NATO Advanced Study Institute. They begin with a description of the major approaches to magnetic confinement: tandem (ambipolar) mirrors with their associated auxiliary barriers, tokamaks, and stellarators. The leading alternatives, the ELMO Bumpy Torus and the reversed field pinch, are also treated. The evolution equations for particle, energy, and (where relevant) field diffusion are presented and discussed. This is the context for atomic and molecular processes relevant to confinement.

  10. Many-body physics using cold atoms

    NASA Astrophysics Data System (ADS)

    Sundar, Bhuvanesh

    Advances in experiments on dilute ultracold atomic gases have given us access to highly tunable quantum systems. In particular, there have been substantial improvements in achieving different kinds of interaction between atoms. As a result, utracold atomic gases oer an ideal platform to simulate many-body phenomena in condensed matter physics, and engineer other novel phenomena that are a result of the exotic interactions produced between atoms. In this dissertation, I present a series of studies that explore the physics of dilute ultracold atomic gases in different settings. In each setting, I explore a different form of the inter-particle interaction. Motivated by experiments which induce artificial spin-orbit coupling for cold fermions, I explore this system in my first project. In this project, I propose a method to perform universal quantum computation using the excitations of interacting spin-orbit coupled fermions, in which effective p-wave interactions lead to the formation of a topological superfluid. Motivated by experiments which explore the physics of exotic interactions between atoms trapped inside optical cavities, I explore this system in a second project. I calculate the phase diagram of lattice bosons trapped in an optical cavity, where the cavity modes mediates effective global range checkerboard interactions between the atoms. I compare this phase diagram with one that was recently measured experimentally. In two other projects, I explore quantum simulation of condensed matter phenomena due to spin-dependent interactions between particles. I propose a method to produce tunable spin-dependent interactions between atoms, using an optical Feshbach resonance. In one project, I use these spin-dependent interactions in an ultracold Bose-Fermi system, and propose a method to produce the Kondo model. I propose an experiment to directly observe the Kondo effect in this system. In another project, I propose using lattice bosons with a large hyperfine spin

  11. Physics, History, and the German Atomic Bomb.

    PubMed

    Walker, Mark

    2017-04-27

    Physics, History, and the German Atomic Bomb. This paper examines the German concept of a nuclear weapon during National Socialism and the Second World War. Zusammenfassung: Physik, Geschichte und die deutsche Atombombe. Dieser Aufsatz untersucht die deutsche Vorstellung einer nuklearen Waffe während des Nationalsozialismus und des Zweiten Weltkrieges. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Cold Atoms, Statistical Physics and Quantum Simulations

    DTIC Science & Technology

    2010-07-22

    to be the development of robust theoretical techniques for the simulations of ultra-cold Bose gases and other quantum phenomena, such theoretical...finite-temperature effects in atom-chip interferometry of Bose -Einstein condensates, R. G. Scott, et al., Physical Review A, 063624 (2009). A copy of...March 2009. Mr Hodder was supported through a University of Otago Scholarship. He initially developed a simple single-site Hubbard model, which can be

  13. Handbook explaining the fundamentals of nuclear and atomic physics

    NASA Technical Reports Server (NTRS)

    Hanlen, D. F.; Morse, W. J.

    1969-01-01

    Indoctrination document presents nuclear, reactor, and atomic physics in an easy, straightforward manner. The entire subject of nuclear physics including atomic structure ionization, isotopes, radioactivity, and reactor dynamics is discussed.

  14. Atomic physics with vapor-cell clocks

    NASA Astrophysics Data System (ADS)

    McGuyer, Bart Hunter

    The most widely used atomic frequency standards (or clocks) are based on the microwave resonant frequencies of optically pumped vapors of alkali-metal atoms in glass cells filled with buffer gas. These vapor-cell clocks are secondary, not primary frequency standards mainly because of the light and pressure shifts, which alter the resonant frequencies of the alkali-metal atoms. This dissertation presents studies of atomic physics important to vapor-cell clocks and, in particular, their accuracy. First, we report a simple method to suppress the light shift in optical pumping systems. This method uses only frequency modulation of a radio frequency or microwave source, which excites an atomic resonance, to simultaneously lock the source frequency to the atomic resonance and lock the pumping light frequency to suppress the light shift. This technique can be applied to many optical pumping systems that experience light shifts. It is especially useful for atomic clocks because it improves the long-term performance, reduces the influence of a pumping laser, and requires less equipment than previous methods. Next, we present three studies of the pressure shift, starting with an estimation of the hyperfine-shift potential that is responsible for most of the pressure shift. We then show that the microwave resonant frequencies of ground-state Rb and Cs atoms in Xe buffer gas have a relatively large nonlinear dependence on the Xe pressure, presumably because of short-lived RbXe and CsXe van der Waals molecules. The Xe data show striking discrepancies with the previous theory for nonlinear shifts, most of which is eliminated by accounting for the spin-rotation interaction in addition to the hyperfine-shift interaction in the molecules. To the limit of our experimental accuracy, the shifts of Rb and Cs in He, Ne, and N2 were linear with pressure. We then consider the prospects for suppressing the pressure shift with buffer-gas mixtures and feedback. Finally, we report an

  15. Atomic physics at the advanced photon source

    SciTech Connect

    Berry, H.G.; Cowan, P.L.; Gemmell, D.S.

    1995-08-01

    Argonne`s 7-GeV synchrotron light source (APS) is expected to commence operations for research early in FY 1996. The Basic Energy Sciences Synchrotron Research Center (BESSRC) is likewise expected to start its research programs at that time. As members of the BESSRC CAT (Collaborative Access Team), we are preparing, together with atomic physicists from the University of Western Michigan, the University of Tennessee, and University of Notre Dame, to initiate a series of atomic physics experiments that exploit the unique capabilities of the APS, especially its high brilliance for photon energies extending from about 3 keV to more than 50 keV. Most of our early work will be conducted on an undulator beam line and we are thus concentrating on various aspects of that beam line and its associated experimental areas. Our group has undertaken responsibilities in such areas as hutch design, evaluation of undulator performance, user policy, interfacing and instrumentation, etc. Initial experiments will probably utilize existing apparatus. We are, however, planning to move rapidly to more sophisticated measurements involving, for example, ion-beam targets, simultaneous laser excitation, and the spectroscopy of emitted photons.

  16. Astronomy-inspired Atomic and Molecular Physics

    NASA Astrophysics Data System (ADS)

    Rau, A. R. P.

    2002-02-01

    Aimed at senior undergraduate and first-year graduate students in departments of physics and astronomy, this textbook gives a systematic treatment of atomic and molecular structure and spectra, together with the effect of weak and strong external electromagnetic fields. Topics chosen are those of interest in astronomy and indeed many were inspired by specific astronomical contexts. Examples include the negative ion of hydrogen and the effects of strong magnetic fields such as those occurring on certain white dwarfs and neutron stars. Adiabatic and non-adiabatic handling of electron correlations and application to processes such as dielectronic recombination are included. Astronomical examples are provided throughout as well as end-of-the chapter problems and exercises. Over seventy illustrative diagrams complete this unique and comprehensive volume. Link: http://www.wkap.nl/prod/b/1-4020-0467-2

  17. Atomic physics and quantum optics using superconducting circuits.

    PubMed

    You, J Q; Nori, Franco

    2011-06-29

    Superconducting circuits based on Josephson junctions exhibit macroscopic quantum coherence and can behave like artificial atoms. Recent technological advances have made it possible to implement atomic-physics and quantum-optics experiments on a chip using these artificial atoms. This Review presents a brief overview of the progress achieved so far in this rapidly advancing field. We not only discuss phenomena analogous to those in atomic physics and quantum optics with natural atoms, but also highlight those not occurring in natural atoms. In addition, we summarize several prospective directions in this emerging interdisciplinary field.

  18. A Laser Stabilization System for Rydberg Atom Physics

    DTIC Science & Technology

    2015-09-06

    A Laser Stabilization System for Rydberg Atom Physics We purchased 2 dual wavelength ultrastable ultralow expansion glass cavities along with optics...Rydberg Atom Physics Report Title We purchased 2 dual wavelength ultrastable ultralow expansion glass cavities along with optics and electronics to...Interactions,” J. Sedlacek and J.P Shaffer, 2nd International Conference on Rydberg Atom Physics , Recife, Brazil (2014). “Production of a 2-D Electron

  19. Atomic physics and non-equilibrium plasmas

    SciTech Connect

    Weisheit, J.C.

    1986-04-25

    Three lectures comprise the report. The lecture, Atomic Structure, is primarily theoretical and covers four topics: (1) Non-relativistic one-electron atom, (2) Relativistic one-electron atom, (3) Non-relativistic many-electron atom, and (4) Relativistic many-electron atom. The lecture, Radiative and Collisional Transitions, considers the problem of transitions between atomic states caused by interactions with radiation or other particles. The lecture, Ionization Balance: Spectral Line Shapes, discusses collisional and radiative transitions when ionization and recombination processes are included. 24 figs., 11 tabs.

  20. Optical physics: Ultrashort light pulses shake atoms

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Taec

    2016-02-01

    The response of electrons in atoms to ultrashort optical light pulses has been probed by measuring the ultraviolet light emitted by the atoms. This reveals that a finite time delay occurs before the response. See Letter p.66

  1. Experiments in atomic and applied physics using synchrotron radiation

    SciTech Connect

    Jones, K.W.

    1987-01-01

    A diverse program in atomic and applied physics using x rays produced at the X-26 beam line at the Brookhaven National Synchrotron Light Source is in progress. The atomic physics program studies the properties of multiply-ionized atoms using the x rays for photo-excitation and ionization of neutral atoms and ion beams. The applied physics program builds on the techniques and results of the atomic physics work to develop new analytical techniques for elemental and chemical characterization of materials. The results are then used for a general experimental program in biomedical sciences, geo- and cosmochemistry, and materials sciences. The present status of the program is illustrated by describing selected experiments. Prospects for development of new experimental capabilities are discussed in terms of a heavy ion storage ring for atomic physics experiments and the feasibility of photoelectron microscopy for high spatial resolution analytical work. 21 refs., 11 figs., 2 tabs.

  2. Project Physics Text 5, Models of the Atom.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Basic atomic theories are presented in this fifth unit of the Project Physics text for use by senior high students. Chemical basis of atomic models in the early years of the 18th Century is discussed n connection with Dalton's theory, atomic properties, and periodic tables. The discovery of electrons is described by using cathode rays, Millikan's…

  3. Quantum dynamics in ultracold atomic physics

    NASA Astrophysics Data System (ADS)

    He, Qiong-Yi; Reid, Margaret D.; Opanchuk, Bogdan; Polkinghorne, Rodney; Rosales-Zárate, Laura E. C.; Drummond, Peter D.

    2012-02-01

    We review recent developments in the theory of quantum dynamics in ultracold atomic physics, including exact techniques and methods based on phase-space mappings that are applicable when the complexity becomes exponentially large. Phase-space representations include the truncated Wigner, positive- P and general Gaussian operator representations which can treat both bosons and fermions. These phase-space methods include both traditional approaches using a phase-space of classical dimension, and more recent methods that use a non-classical phase-space of increased dimensionality. Examples used include quantum Einstein-Podolsky-Rosen (EPR) entanglement of a four-mode BEC, time-reversal tests of dephasing in single-mode traps, BEC quantum collisions with up to 106 modes and 105 interacting particles, quantum interferometry in a multi-mode trap with nonlinear absorption, and the theory of quantum entropy in phase-space. We also treat the approach of variational optimization of the sampling error, giving an elementary example of a nonlinear oscillator.

  4. Chapter Three - Atomic, Molecular, and Optical Physics in the Early Universe: From Recombination to Reionization

    NASA Astrophysics Data System (ADS)

    Glover, Simon C. O.; Chluba, Jens; Furlanetto, Steve R.; Pritchard, Jonathan R.; Savin, Daniel Wolf

    2014-08-01

    Our knowledge of the evolution of the early Universe hinges, in part, on our understanding of the underlying atomic, molecular, and optical (AMO) processes occurring during that epoch. Here we review the relevant AMO physics from when it first became important at a redshift of z ~ 6000, some 18,000 years after the Big Bang when electrons and ions began to recombine. The review continues through the formation of the first stars and galaxies and concludes after the radiation from these first objects has reionized the Universe at a z ~ 10, about a billion years after the Big Bang.

  5. On the utility and ubiquity of atomic collision physics

    SciTech Connect

    Datz, S.

    1989-01-01

    This paper is divided into three parts. In the introduction, we discuss the history and makeup of ICPEAC. In the second part, we discuss the extent of applicability of atomic collision physics. In the third part, we chose one subject (dielectronic excitation) to show the interrelationship of various sub-branches of atomic collision physics. 28 refs., 14 figs.

  6. GENERAL VIEW, LOOKING NORTH, OF ATOMIC PHYSICS OBSERVATORY WHICH CONTAINS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL VIEW, LOOKING NORTH, OF ATOMIC PHYSICS OBSERVATORY WHICH CONTAINS THE WHITE DOME STRUCTURE. THE SHED-LIKE STRUCTURE TO THE LEFT IS THE SEARCH-LIGHT BUILDING. - Carnegie Institution of Washington, Department of Terrestrial Magnetism, Atomic Physics Observatory, 5241 Broad Branch Drive Northwest, Washington, District of Columbia, DC

  7. Atomic Physics, Science (Experimental): 5318.42.

    ERIC Educational Resources Information Center

    Petit, Ralph E.

    Presented is the study of modern and classical concepts of the atom; the structure of the atom as a mass-energy relationship; practical uses of radioactivity; isotopes; and the strange particles. Performance objectives (16) are included as well as a detailed course outline. Experiments, demonstrations, projects and reports to enhance student…

  8. Atomic Structure Calculations from the Los Alamos Atomic Physics Codes

    DOE Data Explorer

    Cowan, R. D.

    The well known Hartree-Fock method of R.D. Cowan, developed at Los Alamos National Laboratory, is used for the atomic structure calculations. Electron impact excitation cross sections are calculated using either the distorted wave approximation (DWA) or the first order many body theory (FOMBT). Electron impact ionization cross sections can be calculated using the scaled hydrogenic method developed by Sampson and co-workers, the binary encounter method or the distorted wave method. Photoionization cross sections and, where appropriate, autoionizations are also calculated. Original manuals for the atomic structure code, the collisional excitation code, and the ionization code, are available from this website. Using the specialized interface, you will be able to define the ionization stage of an element and pick the initial and final configurations. You will be led through a series of web pages ending with a display of results in the form of cross sections, collision strengths or rates coefficients. Results are available in tabular and graphic form.

  9. Atomic physics experiments with stored cooled heavy ion beams

    SciTech Connect

    Datz, S.

    1986-01-01

    The wide ranging interest in the development of heavy ion synchrotrons with electron beam cooling is evident from the number of projects presently under way. Although much of the initial motivation for these rings stemmed from nuclear and particle physics, a considerable amount of atomic physics experimentation is planned. This paper surveys some of the new opportunities in atomic physics which may be made available with storage ring systems. 25 refs., 3 tabs.

  10. Atomic physics: A milestone in quantum computing

    NASA Astrophysics Data System (ADS)

    Bartlett, Stephen D.

    2016-08-01

    Quantum computers require many quantum bits to perform complex calculations, but devices with more than a few bits are difficult to program. A device based on five atomic quantum bits shows a way forward. See Letter p.63

  11. Search for physics beyond the standard model in events with a Z boson, jets, and missing transverse energy in pp collisions at √{ s} = 7 TeV

    NASA Astrophysics Data System (ADS)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Teischinger, F.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Cerny, K.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Charaf, O.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Léonard, A.; Marage, P. E.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Vanelderen, L.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins, M.; De Jesus Damiao, D.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Silva Do Amaral, S. M.; Soares Jorge, L.; Sznajder, A.; Anjos, T. S.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Karadzhinova, A.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, S.; Zhu, B.; Zou, W.; Avila, C.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Dzelalija, M.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Czellar, S.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Korpela, A.; Tuuva, T.; Sillou, D.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dobrzynski, L.; Granier de Cassagnac, R.; Haguenauer, M.; Miné, P.; Mironov, C.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Juillot, P.; Karim, M.; Le Bihan, A.-C.; Van Hove, P.; Fassi, F.; Mercier, D.; Baty, C.; Beauceron, S.; Beaupere, N.; Bedjidian, M.; Bondu, O.; Boudoul, G.; Boumediene, D.; Brun, H.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Falkiewicz, A.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Le Grand, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sordini, V.; Tosi, S.; Tschudi, Y.; Verdier, P.; Viret, S.; Rurua, L.; Anagnostou, G.; Beranek, S.; Edelhoff, M.; Feld, L.; Heracleous, N.

    2012-09-01

    A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (ETmiss). This signature is motivated by BSM physics scenarios, including supersymmetry. The study is performed using a sample of proton-proton collision data collected at √{ s} = 7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 fb-1. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling ETmiss with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.

  12. Strong interaction physics from hadronic atoms

    NASA Astrophysics Data System (ADS)

    Batty, C. J.; Friedman, E.; Gal, A.

    1997-08-01

    Hadronic atoms provide a unique laboratory for studying strong interactions and nuclear medium effects at zero kinetic energy. Previous results from analyses of strong-interaction data consisting of level shifts, widths and yields in π-, K -, p¯ and ∑ - atoms are reviewed. Recent results from fits to comprehensive sets of data in terms of density-dependent optical potentials that respect the low-density limit, where the interaction tends to the free hadron nucleon value, are discussed. The importance of using realistic nuclear density distributions is highlighted. The introduction of density dependence in most cases significantly improves the fit to the data and leads to some novel results. For K - atoms, a substantial attraction of order 200 MeV in nuclear matter is suggested, with interesting repercussions for K¯ condensation and the evolution of strangeness in high-density stars. For p¯ atoms it is found that a reasonable p-wave strength can be accommodated in the fitted optical potential, in agreement with the energy dependence observed for some low-energy p¯N reactions. For ∑ - atoms, the fitted potential becomes repulsive inside the nucleus, implying that Σ hyperons generally do not bind in nuclei in agreement with recent measurements. This repulsion significantly affects calculated masses of neutron stars.

  13. Project Physics Tests 5, Models of the Atom.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Test items relating to Project Physics Unit 5 are presented in this booklet. Included are 70 multiple-choice and 23 problem-and-essay questions. Concepts of atomic model are examined on aspects of relativistic corrections, electron emission, photoelectric effects, Compton effect, quantum theories, electrolysis experiments, atomic number and mass,…

  14. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 2, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) ISOTOPES AND MASS NUMBERS, (2) MEASURING ATOMIC MASS, (3) DISCOVERY OF THE NUCLEUS, (4) STRUCTURE OF THE NUCLEUS, (5) DISCOVERY OF THE NEUTRON, (6) NUCLEAR REACTIONS,…

  15. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 2, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) ISOTOPES AND MASS NUMBERS, (2) MEASURING ATOMIC MASS, (3) DISCOVERY OF THE NUCLEUS, (4) STRUCTURE OF THE NUCLEUS, (5) DISCOVERY OF THE NEUTRON, (6) NUCLEAR REACTIONS,…

  16. Essen and the National Physical Laboratory's atomic clock

    NASA Astrophysics Data System (ADS)

    Henderson, Dale

    2005-06-01

    To commemorate the fiftieth anniversary of the development of the first atomic frequency standard, we present some notes about the work of Louis Essen at the National Physical Laboratory. In addition, we publish below some personal recollections of Essen on his work, which have previously been available only on the Internet (http://www.btinternet.com/~time.lord/TheAtomicClock.htm).

  17. Atomic physics with highly charged ions

    SciTech Connect

    Richard, P.

    1991-08-01

    This report discusses: One electron outer shell processes in fast ion-atom collisions; role of electron-electron interaction in two-electron processes; multi-electron processes at low energy; multi-electron processes at high energy; inner shell processes; molecular fragmentation studies; theory; and, JRM laboratory operations.

  18. NASA GSFC Science Symposium on Atomic and Molecular Physics

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K. (Editor)

    2007-01-01

    This document is the proceedings of a conference on atomic and molecular physics in honor of the retirements of Dr. Aaron Temkin and Dr. Richard Drachman. The conference contained discussions on electron, positron, atomic, and positronium physics, as well as a discussion on muon catalyzed fusion. This proceedings document also contains photographs taken at the symposium, as well as speeches and a short biography made in tribute to the retirees.

  19. Research in Dense Plasma Atomic Physics.

    DTIC Science & Technology

    1984-04-19

    atomic properties up to r of order two (for neon). Debye - Huckel theory is not a meaningful approximation in strongly coupled plasmas. Nor can we...consequently one can expect that the Debye - Huckel theory would be inadequate for the description of plasma properties. This is demonstrated by...the Debye - Huckel (DH) and ion-sphere (IS) calculations when 13 < r < 1 Models We consider an ion of nuclear charge Z in a plasma in which the average

  20. Atoms in Flight: The Remarkable Connections between Atomic and Hadronic Physics

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2012-02-16

    Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD.

  1. The Common Elements of Atomic and Hadronic Physics

    SciTech Connect

    Brodsky, Stanley J.

    2015-02-26

    Atomic physics and hadronic physics are both governed by the Yang Mills gauge theory Lagrangian; in fact, Abelian quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics can provide important insight into hadronic eigenstates in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of frame-independent light-front relativistic equations of motion consistent with light-front holography which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The production of antihydrogen in flight can provide important insight into the dynamics of hadron production in QCD at the amplitude level. The renormalization scale for the running coupling is unambiguously set in QED; an analogous procedure sets the renormalization scales in QCD, leading to scheme-independent scale-fixed predictions. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, the quark-interchange process and light-front quantization have important applicants for atomic physics and photon science, especially in the relativistic domain.

  2. Optically pumped semiconductor lasers for atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.

    2015-03-01

    Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.

  3. Majorana: From Atomic and Molecular, to Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Pucci, R.; Angilella, G. G. N.

    2006-10-01

    In the centennial of Ettore Majorana's birth (1906-1938?), we re-examine some aspects of his fundamental scientific production in atomic and molecular physics, including a not well known short communication. There, Majorana critically discusses Fermi's solution of the celebrated Thomas-Fermi equation for electron screening in atoms and positive ions. We argue that some of Majorana's seminal contributions in molecular physics already prelude to the idea of exchange interactions (or Heisenberg-Majorana forces) in his later workson theoretical nuclear physics. In all his papers, he tended to emphasize the symmetries at the basis of a physical problem, as well as the limitations, rather than the advantages, of the approximations of the method employed.

  4. Bringing atomic and nuclear physics laboratory data into the classroom

    SciTech Connect

    Norman, Eric B.; Larimer, Ruth-Mary; Rech, Gregory; Lee, Jeffrey; Vue, Chue; Leubane, Tholoana; Zamvil, Kenneth; Guthrie, Laura

    2003-05-27

    To illustrate a number of basic concepts in atomic and nuclear physics, we have developed three websites where students can analyze data from modern laboratories. By working through the on-line procedures, students will become acquainted with characteristic x-ray spectra, the concept of half-life, x-ray fluorescence, and neutron activation analysis.

  5. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 4, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) RADIATION USES AND NUCLEAR FISSION, (2) NUCLEAR REACTORS, (3) ENERGY FROM NUCLEAR REACTORS, (4) NUCLEAR EXPLOSIONS AND FUSION, (5) A COMPREHENSIVE REVIEW, AND (6) A…

  6. Project Physics Reader 5, Models of the Atom.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    As a supplement to Project Physics Unit 5, a collection of articles is presented in this reader for student browsing. Nine excerpts are given under the following headings: failure and success, Einstein, Mr. Tompkins and simultaneity, parable of the surveyors, outside and inside the elevator, the teacher and the Bohr theory of atom, Dirac and Born,…

  7. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 4, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) RADIATION USES AND NUCLEAR FISSION, (2) NUCLEAR REACTORS, (3) ENERGY FROM NUCLEAR REACTORS, (4) NUCLEAR EXPLOSIONS AND FUSION, (5) A COMPREHENSIVE REVIEW, AND (6) A…

  8. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 3, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) NUCLEAR BINDING ENERGY, (2) DISCOVERY OF RADIOACTIVITY, (3) RADIOACTIVE RADIATIONS, (4) ALPHA AND BETA DECAY, (5) BETA DECAY REACTIONS, (6) RADIOACTIVE DATING AND…

  9. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 3, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    THE AUTOINSTRUCTIONAL MATERIALS IN THIS TEXT WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY, OFFERING SELF-TUTORING MATERIAL FOR LEARNING ATOMIC PHYSICS. THE TOPICS COVERED ARE (1) NUCLEAR BINDING ENERGY, (2) DISCOVERY OF RADIOACTIVITY, (3) RADIOACTIVE RADIATIONS, (4) ALPHA AND BETA DECAY, (5) BETA DECAY REACTIONS, (6) RADIOACTIVE DATING AND…

  10. Atomic physics with highly charged ions. Progress report

    SciTech Connect

    Richard, P.

    1994-08-01

    The study of inelastic collision phenomena with highly charged projectile ions and the interpretation of spectral features resulting from these collisions remain as the major focal points in the atomic physics research at the J.R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas. The title of the research project, ``Atomic Physics with Highly Charged Ions,`` speaks to these points. The experimental work in the past few years has divided into collisions at high velocity using the primary beams from the tandem and LINAC accelerators and collisions at low velocity using the CRYEBIS facility. Theoretical calculations have been performed to accurately describe inelastic scattering processes of the one-electron and many-electron type, and to accurately predict atomic transition energies and intensities for x rays and Auger electrons. Brief research summaries are given for the following: (1) electron production in ion-atom collisions; (2) role of electron-electron interactions in two-electron processes; (3) multi-electron processes; (4) collisions with excited, aligned, Rydberg targets; (5) ion-ion collisions; (6) ion-molecule collisions; (7) ion-atom collision theory; and (8) ion-surface interactions.

  11. Strong field atomic physics in the mid-infrared

    SciTech Connect

    Sheehy, B; Martin, J D D; Clatterbuck, T O; Kim, D W; DiMauro, L F; Agostini, P; Schafer, K J; Gaarde, M B; Kulander, K C

    2000-03-15

    We examine strong field atomic physics in a wavelength region (3-4 microns) where very little work has previously been done. The soft photon energy allows the exploration of one-electron atoms with low binding energies (alkali metals). We find that photoionization spectra differ from rare gas studies at shorter wavelengths due to more complex ion core potentials. Harmonic generation is studied, and we find that harmonic bandwidths are consistent with theory and the possibility of compression to pulse widths much shorter than that of the driving pulse. Harmonic yields in the visible and W are sufficient for a complete study of their amplitude and phase characteristics.

  12. Theoretical atomic physics code development I: CATS: Cowan Atomic Structure Code

    SciTech Connect

    Abdallah, J. Jr.; Clark, R.E.H.; Cowan, R.D.

    1988-12-01

    An adaptation of R.D. Cowan's Atomic Structure program, CATS, has been developed as part of the Theoretical Atomic Physics (TAPS) code development effort at Los Alamos. CATS has been designed to be easy to run and to produce data files that can interface with other programs easily. The CATS produced data files currently include wave functions, energy levels, oscillator strengths, plane-wave-Born electron-ion collision strengths, photoionization cross sections, and a variety of other quantities. This paper describes the use of CATS. 10 refs.

  13. Physically representative atomistic modeling of atomic-scale friction

    NASA Astrophysics Data System (ADS)

    Dong, Yalin

    Nanotribology is a research field to study friction, adhesion, wear and lubrication occurred between two sliding interfaces at nano scale. This study is motivated by the demanding need of miniaturization mechanical components in Micro Electro Mechanical Systems (MEMS), improvement of durability in magnetic storage system, and other industrial applications. Overcoming tribological failure and finding ways to control friction at small scale have become keys to commercialize MEMS with sliding components as well as to stimulate the technological innovation associated with the development of MEMS. In addition to the industrial applications, such research is also scientifically fascinating because it opens a door to understand macroscopic friction from the most bottom atomic level, and therefore serves as a bridge between science and engineering. This thesis focuses on solid/solid atomic friction and its associated energy dissipation through theoretical analysis, atomistic simulation, transition state theory, and close collaboration with experimentalists. Reduced-order models have many advantages for its simplification and capacity to simulating long-time event. We will apply Prandtl-Tomlinson models and their extensions to interpret dry atomic-scale friction. We begin with the fundamental equations and build on them step-by-step from the simple quasistatic one-spring, one-mass model for predicting transitions between friction regimes to the two-dimensional and multi-atom models for describing the effect of contact area. Theoretical analysis, numerical implementation, and predicted physical phenomena are all discussed. In the process, we demonstrate the significant potential for this approach to yield new fundamental understanding of atomic-scale friction. Atomistic modeling can never be overemphasized in the investigation of atomic friction, in which each single atom could play a significant role, but is hard to be captured experimentally. In atomic friction, the

  14. Essay: Fifty years of atomic, molecular and optical physics in Physical Review Letters.

    PubMed

    Haroche, Serge

    2008-10-17

    The fiftieth anniversary of Physical Review Letters is a good opportunity to review the extraordinary progress of atomic, molecular, and optical physics reported in this journal during the past half-century. As both a witness and an actor of this story, I recall personal experiences and reflect about the past, present, and possible future of my field of research.

  15. Application of ECR ion source beams in atomic physics

    SciTech Connect

    Meyer, F.W.

    1987-01-01

    The availability of intense, high charge state ion beams from ECR ion sources has had significant impact not only on the upgrading of cyclotron and synchrotron facilities, but also on multicharged ion collision research, as evidenced by the increasing number of ECR source facilities used at least on a part time basis for atomic physics research. In this paper one such facility, located at the ORNL ECR source, and dedicated full time to the study of multicharged ion collisions, is described. Examples of applications of ECR ion source beams are given, based on multicharged ion collision physics studies performed at Oak Ridge over the last few years. 21 refs., 18 figs., 2 tabs.

  16. Atomic and Surface Physics in Tokamak Edge Plasmas

    NASA Astrophysics Data System (ADS)

    Isler, Ralph

    2006-05-01

    Material surfaces in fusion machines are subject to intense heat and particle fluxes. As a result, eroded impurities from the walls and divertor targets constitute an intrinsic component of the plasmas; understanding their production and transport relies on broad applications of atomic physics. Various materials have been used for plasma facing components, e.g., stainless steel, inconel, beryllium, tungsten, gold and graphite, and a number of these may be employed in the ITER tokamak. Because graphite tiles are widely used in present day devices, a large fraction of impurity studies have been concerned with the atomic physics of carbon. Influx rates are measured using spectral line intensities together with collisional-radiative models that are built from detailed calculations of electron excitation and ionization rates. In the cold edge region, ion temperatures and flow rates are determined from Doppler broadenings and shifts of spectral multiplets from low ionization stages, which are fitted to complex theoretical profiles that require calculating nonlinear Zeeman effects. Differentiating the mechanisms of production, such as physical sputtering, chemical sputtering, sublimation, etc., involves comparison of molecular and atomic influxes as well as detailed comparison of measured C I line shapes with those modeled for theoretical velocity distributions produced by the different mechanisms.

  17. [The physics of coal liquid slurry atomization]. Annual report 1992

    SciTech Connect

    Chigier, N.; Brown, W.J.

    1994-06-01

    In order to understand the physics of atomization and to predict and improve the performance of atomizers, a survey on the effects of turbulence on atomization has been made. The influence of gas turbulence intensity on the disintegration of a liquid jet, while a constant mean velocity in both gas and liquid streams has been maintained, has been studied. A study has been made of the influence of changing dynamic surface tension on liquid surface wave characteristics and atomization. The dynamic surface tension of water was changed by adding Triton X-100 non-ionic surfactant into the liquid supplied to a two dimensional slot atomizer. Wave frequencies were measured using laser beam attenuation. Dynamic surface tension changes were found to influence liquid sheet disintegration with little effect on wave frequencies. A series of experiments have been conducted to determine the fundamental processes of injection and atomization of liquid propellants for rocket combustion chambers because of their direct influence on combustion instability. For coaxial injectors, liquid and gas flow rates have been progressively changed. Microphotography was used to obtain details of wave disturbances on liquid surfaces. Direct measurements were made of wavelength and frequency of wave propagation on liquid surfaces. Frequency was found to remain constant along the length of the liquid surface. Pulsations in the liquid jet caused drops to form clusters with the same frequency as that of jet surface waves. Measured frequencies were in the range of those measured in combustion instability experiments. Detailed measurements have been made in the sprays using the phase Doppler particle analyzer. Measurements of drop size, velocity and number density are related to the disintegration process. Increasing turbulence intensity in the gas stream is a very effective means of reducing drop size, increasing spray width, and therefore, improving combustion.

  18. Analysis of the physical atomic forces between noble gas atoms, alkali ions and halogen ions

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Heinbockel, J. H.; Outlaw, R. A.

    1986-01-01

    The physical forces between atoms and molecules are important in a number of processes of practical importance, including line broadening in radiative processes, gas and crystal properties, adhesion, and thin films. The components of the physical forces between noble gas atoms, alkali ions, and halogen ions are analyzed and a data base for the dispersion forces is developed from the literature based on evaluations with the harmonic oscillator dispersion model for higher order coefficients. The Zener model of the repulsive core is used in the context of the recent asymptotic wave functions of Handler and Smith; and an effective ionization potential within the Handler and Smith wave functions is defined to analyze the two body potential data of Waldman and Gordon, the alkali-halide molecular data, and the noble gas crystal and salt crystal data. A satisfactory global fit to this molecular and crystal data is then reproduced by the model to within several percent. Surface potentials are evaluated for noble gas atoms on noble gas and salt crystal surfaces with surface tension neglected. Within this context, the noble gas surface potentials on noble gas and salt crystals are considered to be accurate to within several percent.

  19. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    NASA Technical Reports Server (NTRS)

    Kohel, James M.

    2012-01-01

    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  20. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    NASA Technical Reports Server (NTRS)

    Kohel, James M.

    2012-01-01

    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  1. Attosecond science in atomic, molecular, and condensed matter physics.

    PubMed

    Leone, Stephen R; Neumark, Daniel M

    2016-12-16

    Attosecond science represents a new frontier in atomic, molecular, and condensed matter physics, enabling one to probe the exceedingly fast dynamics associated with purely electronic dynamics in a wide range of systems. This paper presents a brief discussion of the technology required to generate attosecond light pulses and gives representative examples of attosecond science carried out in several laboratories. Attosecond transient absorption, a very powerful method in attosecond science, is then reviewed and several examples of gas phase and condensed phase experiments that have been carried out in the Leone/Neumark laboratories are described.

  2. ITER core imaging X-ray spectroscopy: Atomic physics issues

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Clementson, J.; Widmann, K.; Bitter, M.; Hill, K. W.; Johnson, D.; Barnsley, R.; Chung, H. K.; Safronova, U. I.

    2017-03-01

    The Core Imaging X-Ray Spectrometer (CIXS) will be employed for measurements of the ion temperature and of the toroidal rotation velocity, Ti and vϕ, respectively, as a function of the radius of ITER plasmas. The diagnostic is based on precision determinations of the Doppler broadening, centroid shift, and intensity of the lines of highly ionized heavy impurities using a curved Bragg crystal spectral disperser and imager. The ions under consideration for the diagnostic are those of tungsten, krypton, xenon, iron, and argon. A detailed discussion is given of the need for atomic physics experiments and calculations involving the primary diagnostic lines and their collisional and dielectronic satellites. Such experiments and calculations define the instrument parameters, determine the diagnostic uncertainties, and provide paths for extending the diagnostic capabilities to measure impurity concentrations, electron temperature, and ion transport parameters. Enabling the diagnostic to measure radially dependent ion transport coefficients, in particular, requires a large amount of high-quality atomic data in the form of reliable excitation, ionization, and recombination rate coefficients as well as ionization balance calculations which make use of these data. Because core imaging spectrometers are being developed and implemented on present-day magnetic fusion devices, much of the atomic data are already needed and can be tested in the analysis of existing spectra recorded by these diagnostics.

  3. Recent advances in Rydberg physics using alkaline-earth atoms

    NASA Astrophysics Data System (ADS)

    Dunning, F. B.; Killian, T. C.; Yoshida, S.; Burgdörfer, J.

    2016-06-01

    In this brief review, the opportunities that the alkaline-earth elements offer for studying new aspects of Rydberg physics are discussed. For example, the bosonic alkaline-earth isotopes have zero nuclear spin which eliminates many of the complexities present in alkali Rydberg atoms, permitting simpler and more direct comparison between theory and experiment. The presence of two valence electrons allows the production of singlet and triplet Rydberg states that can exhibit a variety of attractive or repulsive interactions. The availability of weak intercombination lines is advantageous for laser cooling and for applications such as Rydberg dressing. Excitation of one electron to a Rydberg state leaves behind an optically active core ion allowing, for high-L states, the optical imaging of Rydberg atoms and their (spatial) manipulation using light scattering. The second valence electron offers the possibility of engineering long-lived doubly excited states such as planetary atoms. Recent advances in both theory and experiment are highlighted together with a number of possible directions for the future.

  4. Atomic, Molecular, and Optical Physics Workshop Final Report

    SciTech Connect

    Armstrong, Jr., Lloyd

    1997-09-21

    This document contains the final reports from the five panels that comprised a Workshop held to explore future directions, scientific impacts and technological connections of research in Atomic, Molecular and Optical Physics. This workshop was sponsored by the Department of Energy, Office of Basic Energy Sciences, Chemical Sciences Division and was held at the Westfields International Conference Center in Chantilly, Virginia on September 21-24, 1997. The workshop was chaired by Lloyd Armstrong, Jr., University of Southern California and the five panels focused on the following topics: Panel A: Interactions of Atoms and Molecules with Photons - Low Field Daniel Kleppner (Massachusetts Institute of Technology), chair Panel B: Interactions of Atoms and Molecules with Photons - High Field Phil Bucksbaum (University of Michigan), chair Panel C: Surface Interactions with Photons, Electrons, Ions, Atoms and Molecules J. Wayne Rabalais (University of Houston), chair Panel D: Theory of Structure and Dynamics Chris Greene (University of Colorado), chair Panel E: Nano- and Mesocopic Structures Paul Alivisatos (Lawrence Berkeley National Laboratory), chair The choice of focus areas reflects areas of significant interest to DOE/BES but is clearly not intended to span all fields encompassed by the designation of atomic, molecular and optical physics, nor even all areas that would be considered for review and funding under DOE’s AMOP program. In a similar vein, not all research that might be suggested under these topics in this report would be appropriate for consideration by DOE’s AMOP program. The workshop format included overview presentations from each of the panel chairs, followed by an intensive series of panel discussion sessions held over a two-day period. The panels were comprised of scientists from the U. S. and abroad, many of whom are not supported by DOE’s AMOP Program. This workshop was held in lieu of the customary “Contractors Meeting” held annually for

  5. The Physical Conditions of Atomic Gas at High Redshift

    NASA Astrophysics Data System (ADS)

    Neeleman, Marcel

    In this thesis we provide insight into the chemical composition, physical conditions and cosmic distribution of atomic gas at high redshift. We study this gas in absorption against bright background quasars in absorption systems known as Damped Ly-alpha Systems (DLAs). These systems contain the bulk of the atomic gas at high redshift and are the likely progenitors of modern-day galaxies. In Chapter 2, we find that the atomic gas in DLAs obeys a mass-metallicity relationship that is similar to the mass-metallicity relationship seen in star-forming galaxies. The evolution of this relationship is linear with redshift, allowing for a planar equation to accurately describe this evolution, which provides a more stringent constraint on simulations modeling DLAs. Furthermore, the concomitant evolution of the mass-metallicity relationship of atomic gas and star-forming galaxies suggests an intimate link between the two. We next use a novel way to measure the physical conditions of the gas by using fine-structure line ratios of singly ionized carbon and silicon. By measuring the density of the upper and lower level states, we are able to determine the temperature, hydrogen density and electron density of the gas. We find that the conditions present in this high redshift gas are consistent with the conditions we see in the local interstellar medium (ISM). A few absorbers have higher than expected pressure, which suggests that they probe the ISM of star-forming galaxies. Finally in Chapter 4, we measure the cosmic neutral hydrogen density at redshifts below 1.6. Below this redshift, the Ly-alpha line of hydrogen is absorbed by the atmosphere, making detection difficult. Using the archive of the Hubble Space Telescope, we compile a comprehensive list of quasars for a search of DLAs at redshift below 1.6. We find that the incidence rate of DLAs and the cosmic neutral hydrogen density is smaller than previously measured, but consistent with the values both locally and at

  6. Davisson-Germer Prize in Atomic or Surface Physics Lecture: Exploring Flatland with Cold Atoms

    NASA Astrophysics Data System (ADS)

    Dalibard, Jean

    2012-06-01

    A two-dimensional Bose fluid is a remarkably rich many-body system, which allows one to revisit several features of quantum statistical physics. Firstly, the role of thermal fluctuations is enhanced compared to the 3D case, which destroys the ordered state associated with Bose-Einstein condensation. However interactions between particles can still cause a superfluid transition, thanks to the Berezinskii-Kosterlitz-Thouless mechanism. Secondly, a weakly interacting Bose fluid in 2D must be scale-invariant, a remarkable feature that manifests itself in the very simple form taken by the equation of state of the fluid. In this talk I will present recent experimental progress in the investigation of 2D atomic gases, which provide a nice illustration of the main features of low dimensional many-body physics.

  7. Atom optics and space physics: A summary of an 'Enrico Fermi' summer school

    NASA Astrophysics Data System (ADS)

    Arimondo, Ennio; Ertmer, Wolfgang; Rasel, Ernst M.; Schleich, Wolfgang P.

    2008-03-01

    We describe the scientific content of the International School of Physics 'Enrico Fermi' on atom optics and space physics, organized by the Italian Physical Society in Varenna at Lake Como, Italy, 2-13 July 2007.

  8. FROM THE HISTORY OF PHYSICS: Moscow State University physics alumni and the Soviet Atomic Project

    NASA Astrophysics Data System (ADS)

    Kiselev, Gennadii V.

    2005-12-01

    In this paper, two closely related themes are addressed: (1) the role that M V Lomonosov Moscow State University (MSU) played in training specialists in physics for the Soviet Atomic Project, and (2) what its alumni contributed to the development of thermonuclear weapons. In its earlier stages, the Soviet Atomic Project was in acute need of qualified personnel, without whom building nuclear and thermonuclear weapons would be an impossible task, and MSU became a key higher educational institution grappled with the training problem. The first part of the paper discusses the efforts of the leading Soviet scientists and leaders of FMD (First Main Directorate) to organize the training of specialists in nuclear physics at the MSU Physics Department and, on the other hand, to create a new Physics and Technology Department at the university. As a result, a number of Soviet Government's resolutions were prepared and issued, part of which are presented in the paper and give an idea of the large-scale challenges this sphere of education was facing at the time. Information is presented for the first time on the early MSU Physics Department graduates in the structure of matter, being employed in the FMD organizations and enterprises from 1948 to 1951. The second part discusses the contribution to the development of thermonuclear weapons by the teams of scientists led by Academicians I E Tamm, A N Tikhonov, and I M Frank, and including MSU physics alumni. The paper will be useful to anyone interested in the history of Russian physics.

  9. The Los Alamos suite of relativistic atomic physics codes

    SciTech Connect

    Fontes, C. J.; Zhang, H. L.; Jr, J. Abdallah; Clark, R. E. H.; Kilcrease, D. P.; Colgan, J.; Cunningham, R. T.; Hakel, P.; Magee, N. H.; Sherrill, M. E.

    2015-05-28

    The Los Alamos SuitE of Relativistic (LASER) atomic physics codes is a robust, mature platform that has been used to model highly charged ions in a variety of ways. The suite includes capabilities for calculating data related to fundamental atomic structure, as well as the processes of photoexcitation, electron-impact excitation and ionization, photoionization and autoionization within a consistent framework. These data can be of a basic nature, such as cross sections and collision strengths, which are useful in making predictions that can be compared with experiments to test fundamental theories of highly charged ions, such as quantum electrodynamics. The suite can also be used to generate detailed models of energy levels and rate coefficients, and to apply them in the collisional-radiative modeling of plasmas over a wide range of conditions. Such modeling is useful, for example, in the interpretation of spectra generated by a variety of plasmas. In this work, we provide a brief overview of the capabilities within the Los Alamos relativistic suite along with some examples of its application to the modeling of highly charged ions.

  10. Probing non-Hermitian physics with flying atoms

    NASA Astrophysics Data System (ADS)

    Wen, Jianming; Xiao, Yanhong; Peng, Peng; Cao, Wanxia; Shen, Ce; Qu, Weizhi; Jiang, Liang

    2016-05-01

    Non-Hermtian optical systems with parity-time (PT) symmetry provide new means for light manipulation and control. To date, most of experimental demonstrations on PT symmetry rely on advanced nanotechnologies and sophisticated fabrication techniques to manmade solid-state materials. Here, we report the first experimental realization of optical anti-PT symmetry, a counterpart of conventional PT symmetry, in a warm atomic-vapor cell. By exploiting rapid coherence transport via flying atoms, we observe essential features of anti-PT symmetry with an unprecedented precision on phase-transition threshold. Moreover, our system allows nonlocal interference of two spatially-separated fields as well as anti-PT assisted four-wave mixing. Besides, another intriguing feature offered by the system is refractionless (or unit-refraction) light propagation. Our results thus represent a significant advance in non-Hermitian physics by bridging a firm connection with the AMO field, where novel phenomena and applications in quantum and nonlinear optics aided by (anti-)PT symmetry can be anticipated.

  11. The Los Alamos suite of relativistic atomic physics codes

    DOE PAGES

    Fontes, C. J.; Zhang, H. L.; Jr, J. Abdallah; ...

    2015-05-28

    The Los Alamos SuitE of Relativistic (LASER) atomic physics codes is a robust, mature platform that has been used to model highly charged ions in a variety of ways. The suite includes capabilities for calculating data related to fundamental atomic structure, as well as the processes of photoexcitation, electron-impact excitation and ionization, photoionization and autoionization within a consistent framework. These data can be of a basic nature, such as cross sections and collision strengths, which are useful in making predictions that can be compared with experiments to test fundamental theories of highly charged ions, such as quantum electrodynamics. The suitemore » can also be used to generate detailed models of energy levels and rate coefficients, and to apply them in the collisional-radiative modeling of plasmas over a wide range of conditions. Such modeling is useful, for example, in the interpretation of spectra generated by a variety of plasmas. In this work, we provide a brief overview of the capabilities within the Los Alamos relativistic suite along with some examples of its application to the modeling of highly charged ions.« less

  12. Efimov Physics in a 6Li-133Cs Atomic Mixture

    NASA Astrophysics Data System (ADS)

    Johansen, Jacob; Feng, Lei; Parker, Colin; Chin, Cheng; Wang, Yujun

    2015-05-01

    We investigate Efimov physics based on three-body recombination in an atomic mixture of 6Li and 133Cs in the vicinity of interspecies Feshbach resonances at 843 and 889 G. This allows us to compare the loss spectra near different resonances and test the universality of Efimov states. Theoretically the Efimov spectrum near 889 G is expected to be similar to that near 843 G, except that the first resonance is absent near the former Feshbach resonance. This is due to the difference in the Cs-Cs scattering length near the two resonances: At 843 G it is negative, whereas at 889 G it is positive. Although it is primarily the Li-Cs interactions that lead to Efimov resonances, the Cs-Cs scattering length is expected to influence the spectrum. This work is supported by NSF and Chicago MRSEC.

  13. Research opportunities in atomic physics at the Advanced Light Source

    NASA Astrophysics Data System (ADS)

    Schlachter, A. S.; Robinson, A. L.

    1989-09-01

    The Advanced Light Source (ALS) now under construction at the Lawrence Berkeley Laboratory is being planned as a national user facility for the production of high-brightness and partially coherent X-ray and ultraviolet synchrotron radiation. The ALS is based on a low-emittance electron storage ring optimized for operation at 1.5 GeV with insertion devices in 11 long straight sections and up to 48 bending-magnet ports. High-brightness photon beams from less than 10 eV to more than 1 keV will be produced by undulators, thereby providing many research opportunities in atomic and molecular physics and chemistry. Wigglers and bending magnets will provide high-flux broad-band radiation at energies to 10 keV.

  14. Atomic Physics in the Quest for Fusion Energy and ITER

    SciTech Connect

    Charles H. Skinner

    2008-02-27

    The urgent quest for new energy sources has led developed countries, representing over half of the world population, to collaborate on demonstrating the scientific and technological feasibility of magnetic fusion through the construction and operation of ITER. Data on high-Z ions will be important in this quest. Tungsten plasma facing components have the necessary low erosion rates and low tritium retention but the high radiative efficiency of tungsten ions leads to stringent restrictions on the concentration of tungsten ions in the burning plasma. The influx of tungsten to the burning plasma will need to be diagnosed, understood and stringently controlled. Expanded knowledge of the atomic physics of neutral and ionized tungsten will be important to monitor impurity influxes and derive tungsten concentrations. Also, inert gases such as argon and xenon will be used to dissipate the heat flux flowing to the divertor. This article will summarize the spectroscopic diagnostics planned for ITER and outline areas where additional data is needed.

  15. Probing physical properties at the nanoscale using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Ditzler, Lindsay Rachel

    Techniques that measure physical properties at the nanoscale with high sensitivity are significantly limited considering the number of new nanomaterials being developed. The development of atomic force microscopy (AFM) has lead to significant advancements in the ability to characterize physical properties of materials in all areas of science: chemistry, physics, engineering, and biology have made great scientific strides do to the versatility of the AFM. AFM is used for quantification of many physical properties such as morphology, electrical, mechanical, magnetic, electrochemical, binding interactions, and protein folding. This work examines the electrical and mechanical properties of materials applicable to the field of nano-electronics. As electronic devices are miniaturized the demand for materials with unique electrical properties, which can be developed and exploited, has increased. For example, discussed in this work, a derivative of tetrathiafulvalene, which exhibits a unique loss of conductivity upon compression of the self-assembled monolayer could be developed into a molecular switch. This work also compares tunable organic (tetraphenylethylene tetracarboxylic acid and bis(pyridine)s assemblies) and metal-organic (Silver-stilbizole coordination compounds) crystals which show high electrical conductivity. The electrical properties of these materials vary depending on their composition allowing for the development of compositionally tunable functional materials. Additional work was done to investigate the effects of molecular environment on redox active 11-ferroceneyl-1 undecanethiol (Fc) molecules. The redox process of mixed monolayers of Fc and decanethiol was measured using conductive probe atomic force microscopy and force spectroscopy. As the concentration of Fc increased large, variations in the force were observed. Using these variations the number of oxidized molecules in the monolayer was determined. AFM is additionally capable of investigating

  16. PHYSICS OF POLARIZED SCATTERING AT MULTI-LEVEL ATOMIC SYSTEMS

    SciTech Connect

    Stenflo, J. O.

    2015-03-01

    The symmetric peak observed in linear polarization in the core of the solar sodium D{sub 1} line at 5896 Å has remained enigmatic since its discovery nearly two decades ago. One reason is that the theory of polarized scattering has not been experimentally tested for multi-level atomic systems in the relevant parameter domains, although the theory is continually being used for the interpretation of astrophysical observations. A laboratory experiment that was set up a decade ago to find out whether the D{sub 1} enigma is a problem of solar physics or quantum physics revealed that the D{sub 1} system has a rich polarization structure in situations where standard scattering theory predicts zero polarization, even when optical pumping of the m state populations of the hyperfine-split ground state is accounted for. Here we show that the laboratory results can be modeled in great quantitative detail if the theory is extended to include the coherences in both the initial and final states of the scattering process. Radiative couplings between the allowed dipole transitions generate coherences in the initial state. Corresponding coherences in the final state are then demanded by a phase closure selection rule. The experimental results for the well understood D{sub 2} line are used to constrain the two free parameters of the experiment, collision rate and optical depth, to suppress the need for free parameters when fitting the D{sub 1} results.

  17. Understanding Solar Coronal Heating through Atomic and Plasma Physics Experiments

    NASA Astrophysics Data System (ADS)

    Savin, Daniel Wolf; Arthanayaka, Thusitha; Bose, Sayak; Hahn, Michael; Beiersdorfer, Peter; Brown, Gregory V.; Gekelman, Walter; Vincena, Steve

    2017-08-01

    Recent solar observations suggest that the Sun's corona is heated by Alfven waves that dissipate at unexpectedly low heights in the corona. These observations raise a number of questions. Among them are the problems of accurately quantifying the energy flux of the waves and that of describing the physical mechanism that leads to the wave damping. We are performing laboratory experiments to address both of these issues.The energy flux depends on the electron density, which can be measured spectroscopically. However, spectroscopic density diagnostics have large uncertainties, because they depend sensitively on atomic collisional excitation, de-excitation, and radiative transition rates for multiple atomic levels. Essentially all of these data come from theory and have not been experimentally validated. We are conducting laboratory experiments using the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory that will provide accurate empirical calibrations for spectroscopic density diagnostics and which will also help to guide theoretical calculations.The observed rapid wave dissipation is likely due to inhomogeneities in the plasma that drive flows and currents at small length scales where energy can be more efficiently dissipated. This may take place through gradients in the Alfvén speed along the magnetic field, which causes wave reflection and generates turbulence. Alternatively, gradients in the Alfvén speed across the field can lead to dissipation through phase-mixing. Using the Large Plasma Device (LAPD) at the University of California Los Angeles, we are studying both of these dissipation mechanisms in the laboratory in order to understand their potential roles in coronal heating.

  18. Understanding Solar Coronal Heating through Atomic and Plasma Physics Experiments

    NASA Astrophysics Data System (ADS)

    Savin, Daniel Wolf; Arthanayaka, Thusitha; Beiersdorfer, Peter; Brown, Gregory V.; Gekelman, Walter; Hahn, Michael; Vincena, Steve

    2017-06-01

    Recent solar observations suggest that the Sun's corona is heated by Alfven waves that dissipate at unexpectedly low heights in the corona. These observations raise a number of questions. Among them are the problems of accurately quantifying the energy flux of the waves and that of describing the physical mechanism that leads to the wave damping. We are performing laboratory experiments to address both of these issues.The energy flux depends on the electron density, which can be measured spectroscopically. However, spectroscopic density diagnostics have large uncertainties, because they depend sensitively on atomic collisional excitation, de-excitation, and radiative transition rates for multiple atomic levels. Essentially all of these data come from theory and have not been experimentally validated. We are conducting laboratory experiments using the electron beam ion trap (EBIT) at Lawrence Livermore National Laboratory that will provide accurate empirical calibrations for spectroscopic density diagnostics and which will also help to guide theoretical calculations.The observed rapid wave dissipation is likely due to inhomogeneities in the plasma that drive flows and currents at small length scales where energy can be more efficiently dissipated. This may take place through gradients in the Alfven speed along the magnetic field, which causes wave reflection and generates turbulence. Alternatively, gradients in the Alfven speed across the field can lead to dissipation through phase-mixing. Using the Large Plasma Device (LAPD) at the University of California Los Angeles, we are studying both of these dissipation mechanisms in the laboratory in order to understand their potential roles in coronal heating.

  19. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 1, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    AUTOINSTRUCTIONAL MATERIALS WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY OF THE SELF-TUTORING APPROACH IN EDUCATION. THE MATERIALS COVER SECTIONS ON (1) THE ATOM, (2) ATOMIC PARTICLES, (3) CATHODE RAYS, (4) MEASURING THE ELECTRON, (5) CHARGE AND MASS OF THE ELECTRON, AND (6) MASS OF ATOMS. RELATED REPORTS ARE ED 003 205 THROUGH ED 003 207, ED…

  20. ATOMIC PHYSICS, AN AUTOINSTRUCTIONAL PROGRAM, VOLUME 1, SUPPLEMENT.

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

    AUTOINSTRUCTIONAL MATERIALS WERE PREPARED FOR USE IN AN EXPERIMENTAL STUDY OF THE SELF-TUTORING APPROACH IN EDUCATION. THE MATERIALS COVER SECTIONS ON (1) THE ATOM, (2) ATOMIC PARTICLES, (3) CATHODE RAYS, (4) MEASURING THE ELECTRON, (5) CHARGE AND MASS OF THE ELECTRON, AND (6) MASS OF ATOMS. RELATED REPORTS ARE ED 003 205 THROUGH ED 003 207, ED…

  1. The Role of Theoretical Atomic Physics in Astrophysical Plasma Modeling

    NASA Astrophysics Data System (ADS)

    Gorczyca, Tom

    2008-05-01

    The interpretation of cosmic spectra relies on a vast sea of atomic data which are not readily obtainable from analytic expressions or simple calculations. Since experimental determination of the multitude of atomic excitation, ionization, and recombination rates is clearly impossible, theoretical calculations are required for all transitions of all ionization stages of all elements through the iron peak elements, and to achieve the accuracy necessary for interpreting the most recently observed, high-resolution spectra, state-of-the-art atomic theoretical techniques need to be used. In this talk, I will give an overview of the latest status of the theoretical treatments of atomic processes in astrophysical plasmas, including a description of the available atomic databases. The successes of atomic theory, as assessed by benchmarking computational results with experimental measurements, where available, will be discussed as well as the present challenges facing the theoretical atomic laboratory astrophysics community.

  2. Search for physics beyond the standard model in events with a Z boson, jets, and missing transverse energy in pp collisions at sqrt(s) = 7 TeV

    SciTech Connect

    Chatrchyan, S.; et al.,

    2012-09-01

    A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (MET). This signature is motivated by BSM physics scenarios, including supersymmetry. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 inverse femtobarns. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling MET with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.

  3. Atomic physics in the quest for fusion energy and ITER

    NASA Astrophysics Data System (ADS)

    Skinner, Charles H.

    2009-05-01

    The urgent quest for new energy sources has led developed countries, representing over half of the world population, to collaborate on demonstrating the scientific and technological feasibility of magnetic fusion through the construction and operation of the international thermonuclear experimental reactor (ITER). Data on high-Z ions will be important in this quest. Tungsten plasma facing components have the necessary low erosion rates and low tritium retention but the high radiative efficiency of tungsten ions leads to stringent restrictions on the concentration of tungsten ions in the burning plasma. The influx of tungsten to the burning plasma will need to be diagnosed, understood and stringently controlled. Expanded knowledge of the atomic physics of neutral and ionized tungsten will be important to monitor impurity influxes and derive tungsten concentrations. Also, inert gases such as argon and xenon will be used to dissipate the heat flux flowing to the divertor. This paper will summarize the spectroscopic diagnostics planned for ITER and outline areas where additional data are needed.

  4. Difference-frequency combs in cold atom physics

    NASA Astrophysics Data System (ADS)

    Kliese, Russell; Hoghooghi, Nazanin; Puppe, Thomas; Rohde, Felix; Sell, Alexander; Zach, Armin; Leisching, Patrick; Kaenders, Wilhelm; Keegan, Niamh C.; Bounds, Alistair D.; Bridge, Elizabeth M.; Leonard, Jack; Adams, Charles S.; Cornish, Simon L.; Jones, Matthew P. A.

    2016-12-01

    Optical frequency combs provide the clockwork to relate optical frequencies to radio frequencies. Hence, combs allow optical frequencies to be measured with respect to a radio frequency where the accuracy is limited only by the reference signal. In order to provide a stable link between the radio and optical frequencies, the two parameters of the frequency comb must be fixed: the carrier envelope offset frequency, f ceo, and the pulse repetition-rate, f rep. We have developed the first optical frequency comb based on difference frequency generation (DFG) that eliminates f ceo by design — specifically tailored for applications in cold atom physics. An f ceo-free spectrum at 1550 nm is generated from a super continuum spanning more than an optical octave. Established amplification and frequency conversion techniques based on reliable telecom fibre technology allow the generation of multiple wavelength outputs. The DFG comb is a convenient tool to both stabilise laser sources and accurately measure optical frequencies in Rydberg experiments and more generally in quantum optics. In this paper we discuss the frequency comb design, characterization, and optical frequency measurement of Strontium Rydberg states. The DFG technique allows for a compact and robust, passively f ceo stable frequency comb significantly improving reliability in practical applications.

  5. Turbulence and atomic physics in magnetically confined plasmas

    NASA Astrophysics Data System (ADS)

    Marandet, Y.; Bufferand, H.; Ciraolo, G.; Nace, N.; Serre, E.; Tamain, P.; Valentinuzzi, M.

    2017-03-01

    An overview of issues related to the interplay between atomic process and turbulence in the peripheral regions of magnetically confined fusion devices is presented. Both atomic processes and turbulence play key roles for fusion, but have most of the time been treated separately. The effects of fluctuations on the time averaged ionization balance, on the transport of neutral particles (atoms and molecules) are discussed, using stochastic models to generate fluctuations with statistically relevant properties. Then applications to optical diagnostics of turbulence, namely gas puff imaging and beam emission spectroscopy are discussed.

  6. Ultimate statistical physics: fluorescence of a single atom

    NASA Astrophysics Data System (ADS)

    Pomeau, Yves; Le Berre, Martine; Ginibre, Jean

    2016-10-01

    We discuss the statistics of emission of photons by a single atom or ion illuminated by a laser beam at the frequency of quasi-resonance between two energy levels, a situation that corresponds to real experiments. We extend this to the case of two laser beams resonant with the energy differences between two excited levels and the ground state (three level atom in V-configuration). We use a novel approach to this type of problem by considering a Kolmogorov equation for the probability distribution of the atomic state, which takes into account first the deterministic evolution of this state under the effect of the incoming laser beam and second the random emission of photons during the spontaneous decay of the excited state(s) to the ground state. This approach yields solvable equations in the two level atom case. For the three level atom case we set the problem and clearly define its frame. The results obtained are valid in both opposite limits of rare and frequent spontaneous decay, compared to the period of the optical Rabi oscillations due to the interaction between resonant excitation and atomic levels. Our analysis gives access to various statistical properties of the fluorescence light, including one showing that its fluctuations in time are not invariants under time reversal. This result makes evident the fundamentally irreversible character of quantum measurements, represented here by the emission of photons of fluorescence.

  7. ATOMIC AND MOLECULAR PHYSICS: Ultra-Slow Atomic Beam Generation by Velocity Selective Resonance

    NASA Astrophysics Data System (ADS)

    Ma, Hong-Yu; Cheng, Hua-Dong; Wang, Yu-Zhu; Liu, Liang; Metcalf, Harold

    2008-05-01

    We describe a method to generate an ultra-slow atomic beam by velocity selective resonance (VSR). A VSR experiment on a metastable helium beam in a magnetic field is presented and the results show that the transverse velocity of the deflected beam can be cooled and precisely controlled to less than the recoil velocity, depending on the magnitude of the magnetic field. We extend this idea to a cold atomic cloud to produce an ultra slow 87Rb beam that can be used as a source of an atomic fountain clock or a space clock.

  8. Pre-Service Physics Teachers' Ideas on Size, Visibility and Structure of the Atom

    ERIC Educational Resources Information Center

    Unlu, Pervin

    2010-01-01

    Understanding the atom gives the opportunity to both understand and conceptually unify the various domains of science, such as physics, chemistry, biology, astronomy and geology. Among these disciplines, physics teachers are expected to be particularly well educated in this topic. It is important that pre-service physics teachers know what sort of…

  9. Pre-Service Physics Teachers' Ideas on Size, Visibility and Structure of the Atom

    ERIC Educational Resources Information Center

    Unlu, Pervin

    2010-01-01

    Understanding the atom gives the opportunity to both understand and conceptually unify the various domains of science, such as physics, chemistry, biology, astronomy and geology. Among these disciplines, physics teachers are expected to be particularly well educated in this topic. It is important that pre-service physics teachers know what sort of…

  10. Inelastic processes in atomic, molecular and chemical physics (in honour of Andrey K. Belyaev)

    NASA Astrophysics Data System (ADS)

    Barklem, Paul S.; Tscherbul, Timur V.

    2015-11-01

    This Special Issue is dedicated to Professor Andrey K. Belyaev, on the occasion of his 60th birthday and in celebration of his productive career in theoretical atomic, molecular, and chemical physics. It brings together 12 research studies of Inelastic Processes in Atomic, Molecular and Chemical Physics, a research area where Andrey himself made significant contributions. Inelastic processes are central to many different areas of physics, including atmospheric physics, astrophysics, and plasma physics to name a few, as well as in related technological applications such as lasers and fusion reactors. Quantitative understanding of the mechanisms of inelastic processes in atoms and molecules is therefore a problem of fundamental importance in physics, astrophysics, and chemistry. It is precisely this challenging problem that Andrey's research addresses using a broad arsenal of theoretical tools and techniques.

  11. Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems

    ERIC Educational Resources Information Center

    Taber, Keith S.

    2013-01-01

    Comparing the atom to a "tiny solar system" is a common teaching analogy, and the extent to which learners saw the systems as analogous was investigated. English upper secondary students were asked parallel questions about the physical interactions between the components of a simple atomic system and a simple solar system to investigate…

  12. Upper Secondary Students' Understanding of the Basic Physical Interactions in Analogous Atomic and Solar Systems

    ERIC Educational Resources Information Center

    Taber, Keith S.

    2013-01-01

    Comparing the atom to a "tiny solar system" is a common teaching analogy, and the extent to which learners saw the systems as analogous was investigated. English upper secondary students were asked parallel questions about the physical interactions between the components of a simple atomic system and a simple solar system to investigate…

  13. Request for Support for the Conference on Super Intense Laser Atom Physics

    SciTech Connect

    Todd Ditmire

    2004-10-21

    The Conference on Super Intense Laser Atom Physics (SILAP) was held in November 2003 in Dallas, Texas. The venue for the meeting was South Fork Ranch in the outskirts of Dallas. The topics of the meeting included high harmonic generation and attosecond pulse generation, strong field interactions with molecules and clusters, particle acceleration, and relativistic laser atom interactions.

  14. Search for physics beyond the Standard Model in pp collisions at the CMS experiment with a signature of a Z boson plus missing transverse energy

    NASA Astrophysics Data System (ADS)

    Wang, Ren-Jie

    The Standard Model of elementary particles is a theory that describes the fundamental structure of matter and interactions among the elementary particles. While the gravitational evidence for the existence of Dark Matter (DM) is overwhelming, there is no good DM candidate in the Standard Model framework, and there is no evidence yet for non-gravitational interactions between DM and Standard Model particles. Therefore, the first analysis performed in this dissertation searches for evidence of particle DM production at the LHC. It uses events containing two charged leptons, consistent with the decay of a Z boson, and large missing transverse momentum. This study is based on data collected with the CMS detector corresponding to an integrated luminosity of 19.7-1 of proton-proton collisions at the LHC at a center-of-mass energy of 8~TeV. No excess of events is observed above the number expected from the Standard Model contributions. The results are interpreted in terms of 90% confidence level limits on the DM-nucleon scattering cross section, as a function of the DM particle mass, for both spin-dependent and spin-independent scenarios. Limits are set on the effective cutoff scale, and on the annihilation rate for DM particles, assuming that their branching fraction to quarks is 100%. Additionally, the most stringent 95% confidence level limits to date on the unparticle model parameters are obtained. A second analysis is performed here to search for invisible decays of Higgs bosons using the same final states but in associated ZH production modes, with Z → l+l--. The study uses the full 2011 and 2012 data samples at 7 TeV and 8 TeV, respectively. The searches are sensitive to non-Standard-Model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. The observed data are consistent with the expected Standard Model backgrounds. Limits are set on the production cross

  15. ECR-based atomic collision physics research at ORNL

    SciTech Connect

    Meyer, F.W.; Bannister, M.E.; Hale, J.W.; Havener, C.C.

    1997-04-01

    After a brief summary of the present capability and configuration of the ORNL Multicharged Ion Research Facility (MIRF), and of upcoming upgrades and expansions, the presently on-line atomic collisions experiments are described. In the process, the utility of intense, cw ion beams extracted from ECR ion sources for low-signal rate experiments is illustrated.

  16. "Reaction Microscopes": The "Cloud Chambers" of Atomic and Molecular Physics

    NASA Astrophysics Data System (ADS)

    Ullrich, Joachim

    2004-09-01

    Reaction-Microscopes, developed 10 years ago in order to investigate fast ion-atom collisions [1], allow to determine the complete vector momenta of several electrons and ions emerging as a result of the fragmentation of single atoms, molecules or clusters interacting with electrons, ions, single photons or intense laser pulses. Thus, the complete final-state many-particle wave function in momentum space becomes observable for single and multiple ionisation of atoms as well as for the dissociation of molecules [2]. In the talk the working principle of these machines will be described. Illustrative examples will be given demonstrating the ability of the method to identify the ``mechanisms'' of single and multiple ionisation for electron and ion impact. Its potential for the investigation of single photon as well as of intense laser-pulse induced fragmentation will be highlighted. Future possibilities to investigate ultra-low-energy electron atom or molecule collisions, laser assisted ionisation, using few-cycle phase controlled laser pulses or future free-electron lasers are envisaged. [1] R. Moshammer et al., Phys. Rev. Lett. 73 (1994) 3371 [2] J. Ullrich et al., Rep. Prog. Phys. 66 (2003) 1463

  17. Summary of informal workshop on state of ion beam facilities for atomic physics research

    SciTech Connect

    Jones, K.W.; Cocke, C.L.; Datz, S.; Kostroun, V.

    1984-11-13

    The present state of ion beam facilities for atomic physics research in the United States is assessed by means of a questionnaire and informal workshop. Recommendations for future facilities are given. 3 refs.

  18. Research in atomic and applied physics using a 6-GeV synchrotron source

    SciTech Connect

    Jones, K.W.

    1985-12-01

    The Division of Atomic and Applied Physics in the Department of Applied Science at Brookhaven National Laboratory conducts a broad program of research using ion beams and synchrotron radiation for experiments in atomic physics and nuclear analytical techniques and applications. Many of the experiments would benefit greatly from the use of high energy, high intensity photon beams from a 6-GeV synchrotron source. A survey of some of the specific scientific possibilities is presented.

  19. Learning Pathways in High-School Level Quantum Atomic Physics.

    ERIC Educational Resources Information Center

    Niedderer, Hans; Petri, Juergen

    Investigations of changes in conceptions during physics instruction are the logical and necessary steps to follow successful international research on students' preinstructional conceptions. The theoretical perspective integrates currently available frameworks of cognition, cognitive states, and cognitive processes in physics. Particular emphasis…

  20. Computational challenges in atomic, molecular and optical physics.

    PubMed

    Taylor, Kenneth T

    2002-06-15

    Six challenges are discussed. These are the laser-driven helium atom; the laser-driven hydrogen molecule and hydrogen molecular ion; electron scattering (with ionization) from one-electron atoms; the vibrational and rotational structure of molecules such as H(3)(+) and water at their dissociation limits; laser-heated clusters; and quantum degeneracy and Bose-Einstein condensation. The first four concern fundamental few-body systems where use of high-performance computing (HPC) is currently making possible accurate modelling from first principles. This leads to reliable predictions and support for laboratory experiment as well as true understanding of the dynamics. Important aspects of these challenges addressable only via a terascale facility are set out. Such a facility makes the last two challenges in the above list meaningfully accessible for the first time, and the scientific interest together with the prospective role for HPC in these is emphasized.

  1. Physics of the missing atoms: technetium and promethium

    SciTech Connect

    Aspden, H.

    1987-05-01

    Technetium (Z = 43) and promethium (Z = 61) are by far the least abundant of all atoms below the radioactive elements (Z = 84 onwards). Their scarcity confirms theoretical predictions emerging from a theory of the photon derived from synchronous lattice electrodynamics. This theory has given precise theoretical values for the fine-structure constant and the constant of gravitation G and is now shown in this paper to indicate resonant interactions between the vacuum lattice oscillations and technetium and promethium. In the case of promethium there is strong reason for believing that this atom can assume supergravitational or antigravitational properties, accounting for its scarcity. This paper not only adds support to the earlier theoretical work on the photon and gravitation, but suggests a research route that might lead to new technology based on controlled interactions with gravity fields.

  2. Atomic physics calculations in support of studies for high energy density plasmas

    SciTech Connect

    Wang, P.; MacFarlane, J.J.; Moses, G.A.; Mehlhorn, T.A.

    1995-12-31

    The studies of high energy density plasmas require basic atomic data, equations of state, opacities, and stopping power. Unfortunately, the related experimental data are very limited. To obtain these data for a wide domain of plasma conditions, one must rely on theoretical calculations. The authors have developed an atomic physics calculation package which can provide high quality atomic data for numerical simulations of high energy density plasmas. In this paper, they give detailed descriptions of physics models used in the package. Particular emphasis will be on a hybrid model for equations of state, a self-consistent field model for ion stopping power, and opacity calculations.

  3. The Atomic Relay: Integrating Physical Education and Science.

    ERIC Educational Resources Information Center

    Menelly, Daniel J.

    1997-01-01

    Presents a lesson plan for teaching abstract science concepts to gifted middle school students. The lesson integrates a physical education component into science instruction to reinforce the abstract notion that electrons emit energy in the form of visible light. (CR)

  4. The Physics of Spin-Polarized Atomic Vapors.

    DTIC Science & Technology

    1985-01-01

    formula (82) (Ref. II). shift methods. In this paper we present the basic theory of spin ex- lower third-body pressures. Essentially the same relaxa- change...polarization during the 129Xe relaxa- The voltages on the capacitors are tion transient the left side of R,, in Fig. 17 is essentially "FM F) at ground...exchange is described by non-linear rate equa- tions. The nonlinearity is essential if one is to account for the spin polarization of both atoms which are

  5. Application of Group Theory to Some Problems in Atomic Physics.

    NASA Astrophysics Data System (ADS)

    Suskin, Mark Albert

    This work comprises three problems, each of which lends itself to investigation via the theory of groups and group representations. The first problem is to complete a set of operators used in the fitting of atomic energy levels of atoms whose ground configuration is f ^ 3. The role of group theory in the labelling of these operators and in their construction is explained. Values of parameters associated with a subset of the operators are also calculated via their group labels. The second problem is to explain the term inversion that occurs between states of the configuration of two equivalent electrons and certain of the states of the half-filled shell. This leads to generalizations that make it possible to investigate correspondences between matrix elements of effective operators taken between states of other configurations besides the two mentioned. This is made possible through the notion of quasispin. The third problem is the construction of recoupling coefficients for groups other than SO(3). Questions of phase convention and Kronecker-product multiplicities are taken up. Several methods of calculation are given and their relative advantages discussed. Tables of values of the calculated 6-j symbols are provided.

  6. PREFACE: 8th Asian International Seminar on Atomic and Molecular Physics (AISAMP)

    NASA Astrophysics Data System (ADS)

    Williams, Jim F.; Buckman, Steve; Bieske, Evan J.

    2009-09-01

    These proceedings arose from the 8th Asian International Seminar on Atomic and Molecular Physics (AISAMP) which was held at the University of Western Australia 24-28 November 2008. The history of AISAMP (Takayanagi and Matsuzawa 2002) recognizes its origin from the Japan-China meeting of 1985, and the first use of the name 'The First Asian International Seminar on Atomic and Molecular Physics (AISAMP)' in 1992. The initial attendees, Japan and China, were joined subsequently by scientists from Korea, Taiwan, India, Australia and recently by Malaysia, Thailand, Vietnam, Turkey Iran, UK and USA. The main purpose of the biennial AISAMP series is to create a wide forum for exchanging ideas and information among atomic and molecular scientists and to promote international collaboration. The scope of the AISAMP8 meeting included pure, strategic and applied research involving atomic and molecular structure and processes in all forms of matter and antimatter. For 2008 the AISAMP conference incorporated the Australian Atomic and Molecular Physics and Quantum Chemistry meeting. The topics for AISAMP8 embraced themes from earlier AISAMP meetings and reflected new interests, in atomic and molecular structures, spectroscopy and collisions; atomic and molecular physics with laser or synchrotron radiation; quantum information processing using atoms and molecules; atoms and molecules in surface physics, nanotechnology, biophysics, atmospheric physics and other interdisciplinary studies. The implementation of the AISAMP themes, as well as the international representation of research interests, is indicated both in the contents list of these published manuscripts as well as in the program for the meeting. Altogether, 184 presentations were made at the 8th AISAMP, including Invited Talks and Contributed Poster Presentations, of which 60 appear in the present Proceedings after review by expert referees in accordance with the usual practice of Journal of Physics: Conference Series of

  7. Project Physics Teacher Guide 5, Models of the Atom.

    ERIC Educational Resources Information Center

    Harvard Univ., Cambridge, MA. Harvard Project Physics.

    Teaching procedures of Project Physics Unit 5 are presented to help teachers make effective use of learning materials. Unit contents are discussed in connection with teaching aid lists, multi-media schedules, schedule blocks, and resource charts. Brief summaries are made for transparencies, 16mm films, and reader articles. Included is information…

  8. Nuclear physics (of the cell, not the atom)

    PubMed Central

    Pederson, Thoru; Marko, John F.

    2014-01-01

    The nucleus is physically distinct from the cytoplasm in ways that suggest new ideas and approaches for interrogating the operation of this organelle. Chemical bond formation and breakage underlie the lives of cells, but as this special issue of Molecular Biology of the Cell attests, the nonchemical aspects of cell nuclei present a new frontier to biologists and biophysicists. PMID:25368422

  9. Physical mechanisms for atomization of a jet spray

    SciTech Connect

    Bower, G.; Chang, S.K.; Corradini, M.L.; El-Beshbeeshy, M.; Martin, J.K.; Krueger, J.

    1988-01-01

    Because combustion in direct injection engines is strongly influenced by the details of the fuel spray in thes engines, the authors have begun a broad research effort of jet breakup experiments and modelling of these high pressure sprays. The main objective of this effort is to better understand fuel injection from the study of the spray-jet breakup process and the associated fuel-oxidant mixing. The focus of this paper is the development of specific models for atomization of the spray-jet. These models are then compared to each other and to preliminary data from the spray-jet breakup experiments. Initial results indicate that KIVA with this proposed spray model shows good agreement with low pressure data (69 MPa) but underestimates spray penetration for higher pressures (104 MPa).

  10. Physics of Optically Pumped Alkali-Metal Atoms

    DTIC Science & Technology

    2013-04-14

    collision broadening and will be almost completely determined by hyperfine structure, natural radiative broadening and Doppler broadening . 3 When pumped by...supported research, and will be an great advantage for work on greenhouse physics. Of particular interest is how collisions of CO2 molecules with the...nitrogen and oxygen molecules of the air affect the way CO2 absorbs and emits radiation. Incorrect modeling of collisional line broadening is one of

  11. Extending synchrotron-based atomic physics experiments into the hard X-ray region

    SciTech Connect

    LeBrun, T.

    1996-12-31

    The high-brightness, hard x-ray beams available from third-generation synchrotron sources are opening new opportunities to study the deepest inner shells of atoms, an area where little work has been done and phenomena not observed in less tightly bound inner-shells are manifested. In addition scattering processes which are weak at lower energies become important, providing another tool to investigate atomic structure as well as an opportunity to study photon/atom interactions beyond photoabsorption. In this contribution the authors discuss some of the issues related to extending synchrotron-based atomic physics experiments into the hard x-ray region from the physical and the experimental point of view. They close with a discussion of a technique, resonant Raman scattering, that may prove invaluable in determining the spectra of the very highly-excited states resulting from the excitation of deep inner shells.

  12. Otto Stern (1888-1969): The founding father of experimental atomic physics

    NASA Astrophysics Data System (ADS)

    Toennies, J. P.; Schmidt-Böcking, H.; Friedrich, B.; Lower, J. C. A.

    2011-12-01

    We review the work and life of Otto Stern who developed the molecular beam technique and with its aid laid the foundations of experimental atomic physics. Among the key results of his research are: the experimental determination of the Maxwell-Boltzmann distribution of molecular velocities (1920), experimental demonstration of space quantization of angular momentum (1922), diffraction of matter waves comprised of atoms and molecules by crystals (1931) and the determination of the magnetic dipole moments of the proton and deuteron (1933).

  13. Clock Technology Development for the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.; Thompson, R. J.; Seidel, D. J.; Kohel, J.; Maleki, L.

    1998-01-01

    The Time and Frequency Sciences and Technology Group at Jet Propulsion Laboratory (JPL) has developed a laser cooling capability for flight and has been selected by NASA to support the Laser-Cooling and Atomic Physics (LCAP) program. Current work in the group includes design and development for tee two laser-cooled atomic clock experiments which have been selected for flight on the International Space Station.

  14. PROBING THE PHYSICAL CONDITIONS OF ATOMIC GAS AT HIGH REDSHIFT

    SciTech Connect

    Neeleman, Marcel; Wolfe, Arthur M.; Prochaska, J. Xavier

    2015-02-10

    A new method is used to measure the physical conditions of the gas in damped Lyα systems (DLAs). Using high-resolution absorption spectra of a sample of 80 DLAs, we are able to measure the ratio of the upper and lower fine-structure levels of the ground state of C{sup +} and Si{sup +}. These ratios are determined solely by the physical conditions of the gas. We explore the allowed physical parameter space using a Monte Carlo Markov chain method to constrain simultaneously the temperature, neutral hydrogen density, and electron density of each DLA. The results indicate that at least 5% of all DLAs have the bulk of their gas in a dense, cold phase with typical densities of ∼100 cm{sup –3} and temperatures below 500 K. We further find that the typical pressure of DLAs in our sample is log (P/k{sub B} ) = 3.4 (K cm{sup –3}), which is comparable to the pressure of the local interstellar medium (ISM), and that the components containing the bulk of the neutral gas can be quite small with absorption sizes as small as a few parsecs. We show that the majority of the systems are consistent with having densities significantly higher than expected for a purely canonical warm neutral medium, indicating that significant quantities of dense gas (i.e., n {sub H} > 0.1 cm{sup –3}) are required to match observations. Finally, we identify eight systems with positive detections of Si II*. These systems have pressures (P/k{sub B} ) in excess of 20,000 K cm{sup –3}, which suggest that these systems tag a highly turbulent ISM in young, star-forming galaxies.

  15. New Phenomena in Physics Related with Single-Atom Electron Sources

    NASA Astrophysics Data System (ADS)

    Akamine, Yuta; Fujiwara, Kazuto; Cho, Bokulae; Oshima, Chuhei

    We have reviewed new phenomena in physics related with development of single-atom electron sources. A collimated electron beam was emitted from the single-atom situated at the top of the nano-pyramids. The following three topics have been discussed. (1) High brightness of electron beam: High-density electrons come out of the source, and overlapping of wave functions presumably produces new phenomena including anti-bunching of electrons in vacuum. Energy spectra showed characteristic features of single-atom electron sources; additional shoulders appeared in the normal spectra. 3) Stable electron emission originates from the field evaporation.

  16. Computation of Free-Free Transitions in Atomic Physics: Foundations

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sucher, J.

    2003-01-01

    The amplitude T for "free-free" processes, such as bremsstrahlung or photo- absorption by an electron in the continuum in the presence of an external field, is usually written as the matrix element of the radiation operator taken between two continuum states. However, unlike the case when at least one of the states is bound, as in radiative transitions, electron capture, or the photo-effect, this expression contains an unphysical term, proportional to a delta-function and is not really the physical amplitude Tphys. This continues to be true for both the velocity and length form of the dipole approximation to the amplitude T. We first give an a priori definition of Tphys in terms of the scattering parts of the continuum functions, which has an obvious interpretation in terms of time-ordered diagrams. We then show that when the formal amplitude is modified by a long- distance cutoff, the modified form approaches Tphys as the cutoff is removed. The modified form then serves as a basis for the definition of a physical velocity dipole amplitude and this in turn leads to an equivalent length form of the dipole amplitude. This exercise provides a clear theoretical basis for many extant calculations in which cutoff factors are introduces somewhat ad hoc, as needed.

  17. Proceedings of the workshop on opportunities for atomic physics using slow, highly-charged ions

    SciTech Connect

    Not Available

    1987-01-01

    The study of atomic physics with highly-charged ions is an area of intense activity at the present time because of a convergence of theoretical interest and advances in experimental techniques. The purpose of the Argonne ''Workshop on Opportunities for Atomic Physics Using Slow, Highly-Charged Ions'' was to bring together atomic, nuclear, and accelerator physicists in order to identify what new facilities would be most useful for the atomic physics community. The program included discussion of existing once-through machines, advanced ion sources, recoil ion techniques, ion traps, and cooler rings. One of the topics of the Workshop was to discuss possible improvement to the ANL Tandem-Linac facility (ATLAS) to enhance the capability for slowing down ions after they are stripped to a high-charge state (the Accel/Decel technique). Another topic was the opportunity for atomic physics provided by the ECR ion source which is being built for the Uranium Upgrade of ATLAS. 18 analytics were prepared for the individual papers in this volume.

  18. Nuclear physics (of the cell, not the atom).

    PubMed

    Pederson, Thoru; Marko, John F

    2014-11-05

    The nucleus is physically distinct from the cytoplasm in ways that suggest new ideas and approaches for interrogating the operation of this organelle. Chemical bond formation and breakage underlie the lives of cells, but as this special issue of Molecular Biology of the Cell attests, the nonchemical aspects of cell nuclei present a new frontier to biologists and biophysicists. © 2014 Pederson and Marko. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  19. ATOMIC AND MOLECULAR PHYSICS: Modelling of a DNA packaging motor

    NASA Astrophysics Data System (ADS)

    Qian, Jun; Xie, Ping; Xue, Xiao-Guang; Wang, Peng-Ye

    2009-11-01

    During the assembly of many viruses, a powerful molecular motor packages the genome into a preassembled capsid. The Bacillus subtilis phage phi29 is an excellent model system to investigate the DNA packaging mechanism because of its highly efficient in vitro DNA packaging activity and the development of a single-molecule packaging assay. Here we make use of structural and biochemical experimental data to build a physical model of DNA packaging by the phi29 DNA packaging motor. Based on the model, various dynamic behaviours such as the packaging rate, pause frequency and slip frequency under different ATP concentrations, ADP concentrations, external loads as well as capsid fillings are studied by using Monte Carlo simulation. Good agreement is obtained between the simulated and available experimental results. Moreover, we make testable predictions that should guide future experiments related to motor function.

  20. V. S. Lebedev and I. L. Beigman, Physics of Highly Excited Atoms and Ions

    NASA Astrophysics Data System (ADS)

    Mewe, R.

    1999-07-01

    This book contains a comprehensive description of the basic principles of the theoretical spectroscopy and experimental spectroscopic diagnostics of Rydberg atoms and ions, i.e., atoms in highly excited states with a very large principal quantum number (n≫1). Rydberg atoms are characterized by a number of peculiar physical properties as compared to atoms in the ground or a low excited state. They have a very small ionization potential (∝1/n2), the highly excited electron has a small orbital velocity (∝1/n), the radius (∝n2) is very large, the excited electron has a long orbital period (∝n3), and the radiation lifetime is very long (∝n3-5). At the same time the R. atom is very sensitive to perturbations from external fields in collisions with charged and neutral targets. In recent years, R. atoms have been observed in laboratory and cosmic conditions for n up to ˜1000, which means that the size amounts to about 0.1 mm, ˜106 times that of an atom in the ground state. The scope of this monograph is to familiarize the reader with today's approaches and methods for describing isolated R. atoms and ions, radiative transitions between highly excited states, and photoionization and photorecombination processes. The authors present a number of efficient methods for describing the structure and properties of R. atoms and calculating processes of collisions with neutral and charged particles as well as spectral-line broadening and shift of Rydberg atomic series in gases, cool and hot plasmas in laboratories and in astrophysical sources. Particular attention is paid to a comparison of theoretical results with available experimental data. The book contains 9 chapters. Chapter 1 gives an introduction to the basic properties of R. atoms (ions), Chapter 2 is devoted to an account of general methods describing an isolated Rydberg atom. Chapter 3 is focussed on the recent achievements in calculations of form factors and dipole matrix elements of different types of

  1. Clock Technology Development in the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Seidel, Dave; Thompson, R. J.; Klipstein, W. M.; Kohel, J.; Maleki, L.

    2000-01-01

    This paper presents the Laser Cooling and Atomic Physics (LCAP) program. It focuses on clock technology development. The topics include: 1) Overview of LCAP Flight Projects; 2) Space Clock 101; 3) Physics with Clocks in microgravity; 4) Space Clock Challenges; 5) LCAP Timeline; 6) International Space Station (ISS) Science Platforms; 7) ISS Express Rack; 8) Space Qualification of Components; 9) Laser Configuration; 10) Clock Rate Comparisons: GPS Carrier Phase Frequency Transfer; and 11) ISS Model Views. This paper is presented in viewgraph form.

  2. PREFACE: 7th Asian International Seminar on Atomic and Molecular Physics

    NASA Astrophysics Data System (ADS)

    Deshmukh, Pranawa C.; Chakraborty, Purushottam; Williams, Jim F.

    2007-09-01

    These proceedings arose from the 7th Asian International Seminar on Atomic and Molecular Physics (AISAMP) which was held at the Indian Institute of Technology, Madras from 4-7 December 2006. The history of the AISAMP has been reviewed by Takayanagi http://www.physics.iitm.ac.in/~aisamp7/history.html. This international seminar/conference series grew out of the Japan-China meetings which were launched in 1985, the fourth of which was held in 1992 and carried a second title: The First Asian International Seminar on Atomic and Molecular Physics (AISAMP), thus providing a formal medium for scientists in this part of the world to report periodically and exchange their scientific thoughts. The founding nations of Japan and China were joined subsequently by Korea, Taiwan, India and Australia. The aims of the symposia included bringing together leading experts and students of atomic and molecular physics, the discussion of important problems, learning and sharing modern techniques and expanding the horizons of modern atomic and molecular physics. The fields of interest ranged from atomic and molecular structure and dynamics to photon, electron and positron scattering, to quantum information processing, the effects of symmetry and many body interactions, laser cooling, cold traps, electric and magnetic fields and to atomic and molecular physics with synchrotron radiation. Particular interest was evident in new techniques and the changes of the physical properties from atomic to condensed matter. Details of the 7th AISAMP, including the topics for the special sessions and the full programme, are available online at the conference website http://www.physics.iitm.ac.in/~aisamp7/. In total, 95 presentations were made at the 7th AISAMP, these included the Invited Talks and Contributed Poster Presentations, of which 52 appear in the present Proceedings after review by expert referees, refereed to the usual standard of the Institute of Physics journal: Journal of Physics B: Atomic

  3. Understanding the physics and chemistry of reaction mechanisms from atomic contributions: a reaction force perspective.

    PubMed

    Vöhringer-Martinez, Esteban; Toro-Labbé, Alejandro

    2012-07-12

    Studying chemical reactions involves the knowledge of the reaction mechanism. Despite activation barriers describing the kinetics or reaction energies reflecting thermodynamic aspects, identifying the underlying physics and chemistry along the reaction path contributes essentially to the overall understanding of reaction mechanisms, especially for catalysis. In the past years the reaction force has evolved as a valuable tool to discern between structural changes and electrons' rearrangement in chemical reactions. It provides a framework to analyze chemical reactions and additionally a rational partition of activation and reaction energies. Here, we propose to separate these energies further in atomic contributions, which will shed new insights in the underlying reaction mechanism. As first case studies we analyze two intramolecular proton transfer reactions. Despite the atom based separation of activation barriers and reaction energies, we also assign the participation of each atom in structural changes or electrons' rearrangement along the intrinsic reaction coordinate. These participations allow us to identify the role of each atom in the two reactions and therfore the underlying chemistry. The knowledge of the reaction chemistry immediately leads us to suggest replacements with other atom types that would facilitate certain processes in the reaction. The characterization of the contribution of each atom to the reaction energetics, additionally, identifies the reactive center of a molecular system that unites the main atoms contributing to the potential energy change along the reaction path.

  4. Physical Construction of the Chemical Atom: Is it Convenient to Go All the Way Back?

    NASA Astrophysics Data System (ADS)

    Izquierdo-Aymerich, Mercè; Adúriz-Bravo, Agustín

    2009-04-01

    In this paper we present an analysis of chemistry texts (mainly textbooks) published during the first half of the 20th century. We show the evolution of the explanations therein in terms of atoms and of atomic structure, when scientists were interpreting phenomena as evidence of the discontinuous, corpuscular structure of matter. In this process of evidence construction, new contributions from physicists and physical chemists that were incorporated to chemical research acquired ‘chemical’ meaning, since they were related to research questions that genuinely came from chemistry. Conversely, the core ideas of 19th-century chemical atomism, among which we must highlight valence and Mendeleev’s periodic system, provided ‘clues’ for imagining an atom in terms of the elements adjusted to their chemical behaviour, which changed periodically as a function of atomic mass. With this, chemistry ceased to be a descriptive science and began to be a ‘law-based’, theoretical science. Little by little, chemistry teaching became the teaching of the internal structure of atoms, which were arranged in the Periodic Table according to criteria and ‘construction rules’ related to quantum mechanics. We pose the question: ‘how can we now teach general chemistry in a way that does not disregard current knowledge about the structure of the atom yet, at the same time, gives priority to chemical criteria, thus making such structure useful to interpret chemical change?’.

  5. Do General Physics Textbooks Discuss Scientists' Ideas about Atomic Structure? A Case in Korea

    ERIC Educational Resources Information Center

    Niaz, Mansoor; Kwon, Sangwoon; Kim, Nahyun; Lee, Gyoungho

    2013-01-01

    Research in science education has recognized the importance of teaching atomic structure within a history and philosophy of science perspective. The objective of this study is to evaluate general physics textbooks published in Korea based on the eight criteria developed in previous research. The result of this study shows that Korean general…

  6. Do General Physics Textbooks Discuss Scientists' Ideas about Atomic Structure? A Case in Korea

    ERIC Educational Resources Information Center

    Niaz, Mansoor; Kwon, Sangwoon; Kim, Nahyun; Lee, Gyoungho

    2013-01-01

    Research in science education has recognized the importance of teaching atomic structure within a history and philosophy of science perspective. The objective of this study is to evaluate general physics textbooks published in Korea based on the eight criteria developed in previous research. The result of this study shows that Korean general…

  7. Physics and Its Multiple Roles in the International Atomic Energy Agency

    NASA Astrophysics Data System (ADS)

    Massey, Charles D.

    2017-01-01

    The IAEA is the world's centre for cooperation in the nuclear field. It was set up as the world's ``Atoms for Peace'' organization in 1957 within the United Nations family. The Agency works with its Member States and multiple partners worldwide to promote the safe, secure and peaceful use of nuclear technologies. Three main areas of work underpin the IAEA's mission: Safety and Security, Science and Technology, and Safeguards and Verification. To carry out its mission, the Agency is authorized to encourage and assist research on, and development and practical application of, atomic energy for peaceful uses throughout the world; foster the exchange of scientific and technical information on peaceful uses of atomic energy; and encourage the exchange of training of scientists and experts in the field of peaceful uses of atomic energy. Nowadays, nuclear physics and nuclear technology are applied in a great variety of social areas, such as power production, medical diagnosis and therapies, environmental protection, security control, material tests, food processing, waste treatments, agriculture and artifacts analysis. This presentation will cover the role and practical application of physics at the IAEA, and, in particular, focus on the role physics has, and will play, in nuclear security.

  8. PREFACE: Atomically controlled fabrication technology: new physics and functional device realization Atomically controlled fabrication technology: new physics and functional device realization

    NASA Astrophysics Data System (ADS)

    Kuwahara, Yuji; Kasai, Hideaki

    2011-10-01

    To realize next generation functional devices, atomic level controllability of the application and fabrication techniques is necessary. The conventional route to advance solid state devices, which involves improvement of 'instrumental accuracy', is now facing a major paradigm shift towards 'phenomenal accuracy'. Therefore, to keep up with this critical turn in the development of devices, pioneering research (both theoretical and experimental) on relevant materials, focusing on new physics at the atomic scale, is inevitable. This special section contains articles on the advancements in fabrication of functional devices with an emphasis on the exploration, clarification and understanding of atomistic phenomena. Research articles reporting theoretical and experimental findings on various materials such as semiconductors, metals, magnetic and organic systems, collectively present and 'capture' the appropriate processes and mechanisms of this rapidly developing field. The theoretical investigations employ first-principles quantum-mechanical simulations to clarify and bring about design principles and guidelines, or to develop more reliable computational methods. Experimental studies, on the other hand, introduce novel capabilities to build, view and manipulate materials at the atomic scale by employing pioneering techniques. Thus, the section pays significant attention to novel structures and properties and the accompanying fabrication techniques and design arising from the understanding of properties and structures at the atomic scale. We hope that researchers in the area of physics, materials science and engineering, interested in the development of functional devices via atomic level control, will find valuable information in this collaborative work. We are grateful to all of the authors for their contributions. Atomically controlled fabrication contents On the mechanism of carbon nanotube formation: the role of the catalyst G N Ayre, T Uchino, B Mazumder, A L Hector

  9. Photoemission from solids: the transition from solid-state to atomic physics

    SciTech Connect

    Shirley, D.A.

    1980-08-01

    As the photon energy is increased, photoemission from solids undergoes a slow transition from solid-state to atomic behavior. However, throughout the energy range h..nu.. = 10 to 1000 eV or higher both types of phenomena are present. Thus angle-resolved photoemission can only be understood quantitatively if each experimenter recognizes the presence of band-structure, photoelectron diffraction, and photoelectron asymmetry effects. The quest for this understanding will build some interesting bridges between solid-state and atomic physics and should also yield important new insights about the phenomena associated with photoemission.

  10. The Advanced Light Source: A new tool for research in atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Schlachter, F.; Robinson, A.

    1991-04-01

    The Advanced Light Source at the Lawrence Berkeley Laboratory will be the world's brightest synchrotron radiation source in the extreme ultraviolet and soft x-ray regions of the spectrum when it begins operation in 1993. It will be available as a national user facility to researchers in a broad range of disciplines, including materials science, atomic and molecular physics, chemistry, biology, imaging, and technology. The high brightness of the ALS will be particularly well suited to high-resolution studies of tenuous targets, such as excited atoms, ions, and clusters.

  11. Atomic Physics Effects on Convergent, Child-Langmuir Ion Flow between Nearly Transparent Electrodes

    SciTech Connect

    Santarius, John F.; Emmert, Gilbert A.

    2013-11-07

    Research during this project at the University of Wisconsin Fusion Technology Institute (UW FTI) on ion and neutral flow through an arbitrary, monotonic potential difference created by nearly transparent electrodes accomplished the following: (1) developed and implemented an integral equation approach for atomic physics effects in helium plasmas; (2) extended the analysis to coupled integral equations that treat atomic and molecular deuterium ions and neutrals; (3) implemented the key deuterium and helium atomic and molecular cross sections; (4) added negative ion production and related cross sections; and (5) benchmarked the code against experimental results. The analysis and codes treat the species D0, D20, D+, D2+, D3+, D and, separately at present, He0 and He+. Extensions enhanced the analysis and related computer codes to include He++ ions plus planar and cylindrical geometries.

  12. Unveiling the structural arrangements responsible for the atomic dynamics in metallic glasses during physical aging

    PubMed Central

    Giordano, V. M.; Ruta, B

    2016-01-01

    Understanding and controlling physical aging, that is, the spontaneous temporal evolution of out-of-equilibrium systems, represents one of the greatest tasks in material science. Recent studies have revealed the existence of a complex atomic motion in metallic glasses, with different aging regimes in contrast with the typical continuous aging observed in macroscopic quantities. By combining dynamical and structural synchrotron techniques, here for the first time we directly connect previously identified microscopic structural mechanisms with the peculiar atomic motion, providing a broader unique view of their complexity. We show that the atomic scale is dominated by the interplay between two processes: rearrangements releasing residual stresses related to a cascade mechanism of relaxation, and medium range ordering processes, which do not affect the local density, likely due to localized relaxations of liquid-like regions. As temperature increases, a surprising additional secondary relaxation process sets in, together with a faster medium range ordering, likely precursors of crystallization. PMID:26787443

  13. Atomic physics with highly charged ions: Progress report, 15 August 1985--14 August 1988

    SciTech Connect

    Richard, P.

    1988-08-01

    The study of inelastic collision phenomena with highly charged projectile ions and the interpretation of spectral features resulting from these collisions remain as the major focal points in the atomic physics research at the J.R. Macdonald Laboratory, Kansas State University, Manhattan, Kansas. The title of the research project ''Atomic Physics with Highly Charged Ions'' speaks to these points. The experimental work is made possible locally by the use of relatively high velocity, highly charged projectiles (v typically 5% c) as obtained from the 6 MV tandem Van de Graaff accelerator. The work in the past few years has divided into collisions at high velocity using the primary beams from the accelerator and collisions at low velocity using secondary beams (recoil ions produced in a high velocity collision) in a so-called SIRS (Secondary Ion Recoil Source) geometry. Theoretical calculations have been performed to accurately describe inelastic scattering processes of the one-electron and many-electron type, and to accurately predict atomic transition energies and intensities for x-rays and Auger electrons. Correlation effects and polarization phenomena in ion-atom collisions have been investigated.

  14. FROM THE HISTORY OF PHYSICS: The development of the first Soviet atomic bomb

    NASA Astrophysics Data System (ADS)

    Goncharov, German A.; Ryabev, Lev D.

    2001-01-01

    In the late 1930s and early 1940s, two remarkable physical phenomena — the fission of heavy nuclei and the chain fission reaction — were discovered, implying that a new powerful source of energy (nuclear fission energy) might become a practical possibility for mankind. At that time, however, the political situation in the world made the development of the atomic bomb the main objective of nuclear energy research in the countries involved. The first atomic bombs, notoriously used in the war against Japan, were produced by the United States of America only six and a half years after the discovery of fission. Four years later, the first Soviet atomic bomb was tested. This was a major step toward the establishment of nuclear parity which led to stability and global peace and thus greatly influenced the destiny of human kind. Based on documentary materials covering the period from 1939 to 1949, this paper traces the origin and evolution of the physical ideas behind the first Soviet atomic bomb and discusses the most important events associated with the project.

  15. Construction and characterization of external cavity diode lasers for atomic physics.

    PubMed

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-04-24

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

  16. Informal proposal for an Atomic Physics Facility at the National Synchrotron Light Source

    SciTech Connect

    Jones, K.W.; Johnson, B.M.; Meron, M.

    1986-01-01

    An Atomic Physics Facility (APF) for experiments that will use radiation from a superconducting wiggler on the NSLS X-13 port is described. The scientific justification for the APF is given and the elements of the facility are discussed. It is shown that it will be possible to conduct a uniquely varied set of experiments that can probe most aspects of atomic physics. A major component of the proposal is a heavy-ion storage ring capable of containing ions with energies of about 10 MeV/nucleon. The ring can be filled with heavy ions produced at the BNL MP Tandem Laboratory or from independent ion-source systems. A preliminary cost estimate for the facility is presented.

  17. Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

    PubMed Central

    Hardman, Kyle S.; Bennetts, Shayne; Debs, John E.; Kuhn, Carlos C. N.; McDonald, Gordon D.; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  18. From the Dawn of Nuclear Physics to the First Atomic Bombs

    NASA Astrophysics Data System (ADS)

    Woolbright, Stephen; Schumacher, Jacob; Michonova-Alexova, Ekaterina

    2014-03-01

    This work gives a fresh look at the major discoveries leading to nuclear fission within the historical perspective. The focus is on the main contributors to the discoveries in nuclear physics, leading to the idea of fission and its application to the creation of the atomic bombs used at the end of the World War II. The present work is a more complete review on the history of the nuclear physics discoveries and their application to the atomic bomb. In addition to the traditional approach to the topic, focusing mainly on the fundamental physics discoveries in Europe and on the Manhattan Project in the United States, the nuclear research in Japan is also emphasized. Along with that, a review of the existing credible scholar publications, providing evidence for possible atomic bomb research in Japan, is provided. Proper credit is given to the women physicists, whose contributions had not always been recognized. Considering the historical and political situation at the time of the scientific discoveries, thought-provoking questions about decision-making, morality, and responsibility are also addressed. The work refers to the contributions of over 20 Nobel Prize winners. EM-A is grateful to Prof. Walter Grunden and to Prof. Emeritus Shadahiko Kano, Prof. Emeritus Monitori Hoshi for sharing their own notes, documents, and references, and to CCCU for sponsoring her participation in the 2013 Nuclear Weapons Seminar in Japan.

  19. Atom lasers, coherent states, and coherence. I. Physically realizable ensembles of pure states

    NASA Astrophysics Data System (ADS)

    Wiseman, H. M.; Vaccaro, John A.

    2002-04-01

    A laser, be it an optical laser or an atom laser, is an open quantum system that produces a coherent beam of bosons (photons or atoms, respectively). Far above threshold, the stationary state ρss of the laser mode is a mixture of coherent-field states with random phase, or, equivalently, a Poissonian mixture of number states. This paper answers the question: can descriptions such as these, of ρss as a stationary ensemble of pure states, be physically realized? Here physical realization is as defined previously by us [H. M. Wiseman and J. A. Vaccaro, Phys. Lett. A 250, 241 (1998)]: an ensemble of pure states for a particular system can be physically realized if, without changing the dynamics of the system, an experimenter can (in principle) know at any time that the system is in one of the pure-state members of the ensemble. Such knowledge can be obtained by monitoring the baths to which the system is coupled, provided that coupling is describable by a Markovian master equation. Using a family of master equations for the (atom) laser, we solve for the physically realizable (PR) ensembles. We find that for any finite self-energy χ of the bosons in the laser mode, the coherent-state ensemble is not PR; the closest one can come to it is an ensemble of squeezed states. This is particularly relevant for atom lasers, where the self-energy arising from elastic collisions is expected to be large. By contrast, the number-state ensemble is always PR. As the self-energy χ increases, the states in the PR ensemble closest to the coherent-state ensemble become increasingly squeezed. Nevertheless, there are values of χ for which states with well-defined coherent amplitudes are PR, even though the atom laser is not coherent (in the sense of having a Bose-degenerate output). We discuss the physical significance of this anomaly in terms of conditional coherence (and hence conditional Bose degeneracy).

  20. Medical physics in Europe following recommendations of the International Atomic Energy Agency.

    PubMed

    Casar, Bozidar; Lopes, Maria do Carmo; Drljević, Advan; Gershkevitsh, Eduard; Pesznyak, Csilla

    2016-03-01

    Medical physics is a health profession where principles of applied physics are mostly directed towards the application of ionizing radiation in medicine. The key role of the medical physics expert in safe and effective use of ionizing radiation in medicine was widely recognized in recent European reference documents like the European Union Council Directive 2013/59/EURATOM (2014), and European Commission Radiation Protection No. 174, European Guidelines on Medical Physics Expert (2014). Also the International Atomic Energy Agency (IAEA) has been outspoken in supporting and fostering the status of medical physics in radiation medicine through multiple initiatives as technical and cooperation projects and important documents like IAEA Human Health Series No. 25, Roles and Responsibilities, and Education and Training Requirements for Clinically Qualified Medical Physicists (2013) and the International Basic Safety Standards, General Safety Requirements Part 3 (2014). The significance of these documents and the recognition of the present insufficient fulfilment of the requirements and recommendations in many European countries have led the IAEA to organize in 2015 the Regional Meeting on Medical Physics in Europe, where major issues in medical physics in Europe were discussed. Most important outcomes of the meeting were the recommendations addressed to European member states and the survey on medical physics status in Europe conducted by the IAEA and European Federation of Organizations for Medical Physics. Published recommendations of IAEA Regional Meeting on Medical Physics in Europe shall be followed and enforced in all European states. Appropriate qualification framework including education, clinical specialization, certification and registration of medical physicists shall be established and international recommendation regarding staffing levels in the field of medical physics shall be fulfilled in particular. European states have clear legal and moral

  1. Medical physics in Europe following recommendations of the International Atomic Energy Agency

    PubMed Central

    Lopes, Maria do Carmo; Drljević, Advan; Gershkevitsh, Eduard; Pesznyak, Csilla

    2016-01-01

    Background Medical physics is a health profession where principles of applied physics are mostly directed towards the application of ionizing radiation in medicine. The key role of the medical physics expert in safe and effective use of ionizing radiation in medicine was widely recognized in recent European reference documents like the European Union Council Directive 2013/59/EURATOM (2014), and European Commission Radiation Protection No. 174, European Guidelines on Medical Physics Expert (2014). Also the International Atomic Energy Agency (IAEA) has been outspoken in supporting and fostering the status of medical physics in radiation medicine through multiple initiatives as technical and cooperation projects and important documents like IAEA Human Health Series No. 25, Roles and Responsibilities, and Education and Training Requirements for Clinically Qualified Medical Physicists (2013) and the International Basic Safety Standards, General Safety Requirements Part 3 (2014). The significance of these documents and the recognition of the present insufficient fulfilment of the requirements and recommendations in many European countries have led the IAEA to organize in 2015 the Regional Meeting on Medical Physics in Europe, where major issues in medical physics in Europe were discussed. Most important outcomes of the meeting were the recommendations addressed to European member states and the survey on medical physics status in Europe conducted by the IAEA and European Federation of Organizations for Medical Physics. Conclusions Published recommendations of IAEA Regional Meeting on Medical Physics in Europe shall be followed and enforced in all European states. Appropriate qualification framework including education, clinical specialization, certification and registration of medical physicists shall be established and international recommendation regarding staffing levels in the field of medical physics shall be fulfilled in particular. European states have clear

  2. Phases and Interfaces from Real Space Atomically Resolved Data: Physics-Based Deep Data Image Analysis.

    PubMed

    Vasudevan, Rama K; Ziatdinov, Maxim; Jesse, Stephen; Kalinin, Sergei V

    2016-09-14

    Advances in electron and scanning probe microscopies have led to a wealth of atomically resolved structural and electronic data, often with ∼1-10 pm precision. However, knowledge generation from such data requires the development of a physics-based robust framework to link the observed structures to macroscopic chemical and physical descriptors, including single phase regions, order parameter fields, interfaces, and structural and topological defects. Here, we develop an approach based on a synergy of sliding window Fourier transform to capture the local analog of traditional structure factors combined with blind linear unmixing of the resultant 4D data set. This deep data analysis is ideally matched to the underlying physics of the problem and allows reconstruction of the a priori unknown structure factors of individual components and their spatial localization. We demonstrate the principles of this approach using a synthetic data set and further apply it for extracting chemical and physically relevant information from electron and scanning tunneling microscopy data. This method promises to dramatically speed up crystallographic analysis in atomically resolved data, paving the road toward automatic local structure-property determinations in crystalline and quasi-ordered systems, as well as systems with competing structural and electronic order parameters.

  3. Phases and interfaces from real space atomically resolved data: Physics-based deep data image analysis

    SciTech Connect

    Vasudevan, Rama K.; Ziatdinov, Maxim; Jesse, Stephen; Kalinin, Sergei V.

    2016-08-12

    Advances in electron and scanning probe microscopies have led to a wealth of atomically resolved structural and electronic data, often with ~1–10 pm precision. However, knowledge generation from such data requires the development of a physics-based robust framework to link the observed structures to macroscopic chemical and physical descriptors, including single phase regions, order parameter fields, interfaces, and structural and topological defects. Here, we develop an approach based on a synergy of sliding window Fourier transform to capture the local analog of traditional structure factors combined with blind linear unmixing of the resultant 4D data set. This deep data analysis is ideally matched to the underlying physics of the problem and allows reconstruction of the a priori unknown structure factors of individual components and their spatial localization. We demonstrate the principles of this approach using a synthetic data set and further apply it for extracting chemical and physically relevant information from electron and scanning tunneling microscopy data. Furthermore, this method promises to dramatically speed up crystallographic analysis in atomically resolved data, paving the road toward automatic local structure–property determinations in crystalline and quasi-ordered systems, as well as systems with competing structural and electronic order parameters.

  4. Phases and interfaces from real space atomically resolved data: Physics-based deep data image analysis

    DOE PAGES

    Vasudevan, Rama K.; Ziatdinov, Maxim; Jesse, Stephen; ...

    2016-08-12

    Advances in electron and scanning probe microscopies have led to a wealth of atomically resolved structural and electronic data, often with ~1–10 pm precision. However, knowledge generation from such data requires the development of a physics-based robust framework to link the observed structures to macroscopic chemical and physical descriptors, including single phase regions, order parameter fields, interfaces, and structural and topological defects. Here, we develop an approach based on a synergy of sliding window Fourier transform to capture the local analog of traditional structure factors combined with blind linear unmixing of the resultant 4D data set. This deep data analysismore » is ideally matched to the underlying physics of the problem and allows reconstruction of the a priori unknown structure factors of individual components and their spatial localization. We demonstrate the principles of this approach using a synthetic data set and further apply it for extracting chemical and physically relevant information from electron and scanning tunneling microscopy data. Furthermore, this method promises to dramatically speed up crystallographic analysis in atomically resolved data, paving the road toward automatic local structure–property determinations in crystalline and quasi-ordered systems, as well as systems with competing structural and electronic order parameters.« less

  5. Phases and interfaces from real space atomically resolved data: Physics-based deep data image analysis

    SciTech Connect

    Vasudevan, Rama K.; Ziatdinov, Maxim; Jesse, Stephen; Kalinin, Sergei V.

    2016-08-12

    Advances in electron and scanning probe microscopies have led to a wealth of atomically resolved structural and electronic data, often with ~1–10 pm precision. However, knowledge generation from such data requires the development of a physics-based robust framework to link the observed structures to macroscopic chemical and physical descriptors, including single phase regions, order parameter fields, interfaces, and structural and topological defects. Here, we develop an approach based on a synergy of sliding window Fourier transform to capture the local analog of traditional structure factors combined with blind linear unmixing of the resultant 4D data set. This deep data analysis is ideally matched to the underlying physics of the problem and allows reconstruction of the a priori unknown structure factors of individual components and their spatial localization. We demonstrate the principles of this approach using a synthetic data set and further apply it for extracting chemical and physically relevant information from electron and scanning tunneling microscopy data. Furthermore, this method promises to dramatically speed up crystallographic analysis in atomically resolved data, paving the road toward automatic local structure–property determinations in crystalline and quasi-ordered systems, as well as systems with competing structural and electronic order parameters.

  6. Optical and magnetic properties of a transparent garnet film for atomic physics experiments

    NASA Astrophysics Data System (ADS)

    Saito, Mari; Tajima, Ryoichi; Kiyosawa, Ryota; Nagata, Yugo; Shimada, Hiroyuki; Ishibashi, Takayuki; Hatakeyama, Atsushi

    2016-12-01

    We investigated the optical and magnetic properties of a transparent magnetic garnet with a particular focus on its applications to atomic physics experiments. The garnet film used in this study was a magnetically soft material that was originally designed for a Faraday rotator at optical communication wavelengths in the near infrared region. The film had a thickness of 2.1 μm and a small optical loss at a wavelength of λ =780 nm resonant with Rb atoms. The Faraday effect was also small and, thus, barely affected the polarization of light at λ =780 nm. In contrast, large Faraday rotation angles at shorter wavelengths enabled us to visualize magnetic domains, which were perpendicularly magnetized in alternate directions with a period of 3.6 μm. We confirmed the generation of an evanescent wave on the garnet film, which can be used for the optical observation and manipulation of atoms on the surface of the film. Finally, we demonstrated a magnetic mirror for laser-cooled Rb atoms using the garnet film.

  7. Resolving all-order method convergence problems for atomic physics applications

    SciTech Connect

    Gharibnejad, H.; Derevianko, A.; Eliav, E.; Safronova, M. S.

    2011-05-15

    The development of the relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Hartree-Fock wave function are included to all orders of perturbation theory led to many important results for the study of fundamental symmetries, development of atomic clocks, ultracold atom physics, and others, as well as provided recommended values of many atomic properties critically evaluated for their accuracy for a large number of monovalent systems. This approach requires iterative solutions of the linearized coupled-cluster equations leading to convergence issues in some cases where correlation corrections are particularly large or lead to an oscillating pattern. Moreover, these issues also lead to similar problems in the configuration-interaction (CI)+all-order method for many-particle systems. In this work, we have resolved most of the known convergence problems by applying two different convergence stabilizer methods, namely, reduced linear equation and direct inversion of iterative subspace. Examples are presented for B, Al, Zn{sup +}, and Yb{sup +}. Solving these convergence problems greatly expands the number of atomic species that can be treated with the all-order methods and is anticipated to facilitate many interesting future applications.

  8. Isotopic Shift of Atom-Dimer Efimov Resonances in K-Rb Mixtures: Critical Effect of Multichannel Feshbach Physics.

    PubMed

    Kato, K; Wang, Yujun; Kobayashi, J; Julienne, P S; Inouye, S

    2017-04-21

    Multichannel Efimov physics is investigated in ultracold heteronuclear admixtures of K and Rb atoms. We observe a shift in the scattering length where the first atom-dimer resonance appears in the ^{41}K-^{87}Rb system relative to the position of the previously observed atom-dimer resonance in the ^{40}K-^{87}Rb system. This shift is well explained by our calculations with a three-body model including van der Waals interactions, and, more importantly, multichannel spinor physics. With only minor differences in the atomic masses of the admixtures, the shift in the atom-dimer resonance positions can be cleanly ascribed to the isolated and overlapping Feshbach resonances in the ^{40}K-^{87}Rb and ^{41}K-^{87}Rb systems, respectively. Our study demonstrates the role of multichannel Feshbach physics in determining Efimov resonances in heteronuclear three-body systems.

  9. Stalking the Anti-Racist Atom: Engaging Educational Equity and Diversity in Physics Teaching

    NASA Astrophysics Data System (ADS)

    Hodari, Apriel K.

    2006-12-01

    One of the first articles I ever read on diversity in physics education stated, “There’s no such thing as an anti-racist atom.” This perspective, that the science of physics is itself inherently unbiased, illustrates the difficulty of engaging our intellectual community on this topic. We genuinely believe that our science is devoid of the complications of the human condition, and therefore we need not worry about these things. It is clear however, as people competing for scarce resources in a non-equitable society, we engage in all of the same behaviors everyone else does, include those that work against equity and diversity. Over the last several years, my colleagues and I have held workshops aimed at addressing educational equity and diversity in physics teaching. In this discussion, I will present some of the questions we have posed, along with lessons learned and ideas about what we can do next.

  10. An open source digital servo for atomic, molecular, and optical physics experiments

    PubMed Central

    Leibrandt, D. R.; Heidecker, J.

    2016-01-01

    We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of 27Al+ in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser. PMID:26724014

  11. Physical properties of the HIV-1 capsid from all-atom molecular dynamics simulations

    DOE PAGES

    Perilla, Juan R.; Schulten, Klaus

    2017-07-19

    Human immunodeficiency virus type 1 (HIV-1) infection is highly dependent on its capsid. The capsid is a large container, made of B 1,300 proteins with altogether 4 million atoms. Though the capsid proteins are all identical, they nevertheless arrange themselves into a largely asymmetric structure made of hexamers and pentamers. The large number of degrees of freedom and lack of symmetry pose a challenge to studying the chemical details of the HIV capsid. Simulations of over 64 million atoms for over 1 μs allow us to conduct a comprehensive study of the chemical–physical properties of an empty HIV-1 capsid, includingmore » its electrostatics, vibrational and acoustic properties, and the effects of solvent (ions and water) on the capsid. Furthermore, the simulations reveal critical details about the capsid with implications to biological function.« less

  12. Testing for a cosmological influence on local physics using atomic and gravitational clocks

    SciTech Connect

    Adams, P.J.; Canuto, V.M.; Goldman, I.; Hellings, R.W.

    1983-10-15

    The existence of a possible influence of the large-scale structure of the Universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic influence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (i) if such a cosmological influence exists at the level of Hubble's constant, and (ii) which category of theories is appropriate for a description of the phenomenon.

  13. Physical properties of the HIV-1 capsid from all-atom molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Perilla, Juan R.; Schulten, Klaus

    2017-07-01

    Human immunodeficiency virus type 1 (HIV-1) infection is highly dependent on its capsid. The capsid is a large container, made of ~1,300 proteins with altogether 4 million atoms. Although the capsid proteins are all identical, they nevertheless arrange themselves into a largely asymmetric structure made of hexamers and pentamers. The large number of degrees of freedom and lack of symmetry pose a challenge to studying the chemical details of the HIV capsid. Simulations of over 64 million atoms for over 1 μs allow us to conduct a comprehensive study of the chemical-physical properties of an empty HIV-1 capsid, including its electrostatics, vibrational and acoustic properties, and the effects of solvent (ions and water) on the capsid. The simulations reveal critical details about the capsid with implications to biological function.

  14. TRIμP-Trapped Radioactive Atoms-μicrolaboratories for Fundamental Physics

    NASA Astrophysics Data System (ADS)

    Jungmann, K.; Berg, G. P.; Dammalapati, U.; Dendooven, P.; Dermois, O.; Harakeh, M. N.; Hoekstra, R.; Morgenstern, R.; Rogachevskiy, A.; Sanchez-Vega, M.; Timmermans, R.; Traykov, E.; Willmann, L.; Wilscut, H. W.

    At the Kernfysisch Versneller Instituut (KVI) in Groningen, NL, a new facility (TRIμP) is under development. Radioactive nuclei will be produced using heavy ion beams from the superconducting AGOR cyclotron. They are then slowed down and finally trapped in ion or atomic traps in order to perform precision experiments with them. The facility will be open for use by the worldwide community. The present local research programme includes precision studies of nuclear β-decays through β-neutrino (recoil nucleus) momentum correlations in weak decays as well as searches for permanent electric dipole moments in heavy atomic systems. Such experiments offer a large potential for discovering new physics or to put sensitive limits on parameters in models beyond standard theory.

  15. An open source digital servo for atomic, molecular, and optical physics experiments

    SciTech Connect

    Leibrandt, D. R. Heidecker, J.

    2015-12-15

    We describe a general purpose digital servo optimized for feedback control of lasers in atomic, molecular, and optical physics experiments. The servo is capable of feedback bandwidths up to roughly 1 MHz (limited by the 320 ns total latency); loop filter shapes up to fifth order; multiple-input, multiple-output control; and automatic lock acquisition. The configuration of the servo is controlled via a graphical user interface, which also provides a rudimentary software oscilloscope and tools for measurement of system transfer functions. We illustrate the functionality of the digital servo by describing its use in two example scenarios: frequency control of the laser used to probe the narrow clock transition of {sup 27}Al{sup +} in an optical atomic clock, and length control of a cavity used for resonant frequency doubling of a laser.

  16. Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Cheng, C.-C.; Bhatia, A. K.

    1980-01-01

    The paper considers the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. Tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences are presented, and collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence are given. Similarities of tokamak and solar spectra are discussed, and it is shown how the atomic data presented may be used to determine ion abundances and electron densities in low-density plasmas.

  17. Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas

    NASA Technical Reports Server (NTRS)

    Feldman, U.; Doschek, G. A.; Cheng, C.-C.; Bhatia, A. K.

    1980-01-01

    The paper considers the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. Tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences are presented, and collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence are given. Similarities of tokamak and solar spectra are discussed, and it is shown how the atomic data presented may be used to determine ion abundances and electron densities in low-density plasmas.

  18. Testing for a cosmological influence on local physics using atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Adams, P. J.; Hellings, R. W.; Canuto, V. M.; Goldman, I.

    1983-01-01

    The existence of a possible influence of the large-scale structure of the universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic infuence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (1) if such a cosmological influence exists at the level of Hubble's constant, and (2) which category of theories is appropriate for a descripton of the phenomenon.

  19. Testing for a cosmological influence on local physics using atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Adams, P. J.; Hellings, R. W.; Canuto, V. M.; Goldman, I.

    1983-01-01

    The existence of a possible influence of the large-scale structure of the universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic infuence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (1) if such a cosmological influence exists at the level of Hubble's constant, and (2) which category of theories is appropriate for a descripton of the phenomenon.

  20. Using an Advanced Computational Laboratory Experiment to Extend and Deepen Physical Chemistry Students' Understanding of Atomic Structure

    ERIC Educational Resources Information Center

    Hoffman, Gary G.

    2015-01-01

    A computational laboratory experiment is described, which involves the advanced study of an atomic system. The students use concepts and techniques typically covered in a physical chemistry course but extend those concepts and techniques to more complex situations. The students get a chance to explore the study of atomic states and perform…

  1. Using an Advanced Computational Laboratory Experiment to Extend and Deepen Physical Chemistry Students' Understanding of Atomic Structure

    ERIC Educational Resources Information Center

    Hoffman, Gary G.

    2015-01-01

    A computational laboratory experiment is described, which involves the advanced study of an atomic system. The students use concepts and techniques typically covered in a physical chemistry course but extend those concepts and techniques to more complex situations. The students get a chance to explore the study of atomic states and perform…

  2. Dips in spectral line profiles and their applications in plasma physics and atomic physics

    NASA Astrophysics Data System (ADS)

    Dalimier, E.; Oks, E.; Renner, O.

    2017-03-01

    We review studies of two kinds of dips in spectral line profiles emitted by plasmas - the dips that have been predicted theoretically and observed experimentally: Langmuir-wave-caused dips (L-dips) and charge-exchange-caused dips (X-dips). There is a principal difference with respect to positions of L-dips and X-dips relative to the unperturbed wavelength of a spectral line: positions of L-dips scale with the electron density Ne roughly as Ne1/2, while positions of X-dips are almost independent of Ne (the dependence is much weaker than for L-dips). L-dips and X-dips phenomena are important both fundamentally and practically. The fundamental importance is due to a rich physics behind each of these phenomena. As for important practical applications, they are as follows. Observations of L-dips constitute a very accurate method to measure the electron density in plasmas - the method that does not require the knowledge of the electron temperature. L-dips also allow measuring the amplitude of the electric field of Langmuir waves - the only one spectroscopic method available for this purpose. Observations of X-dips provide an opportunity to determine rate coefficient of charge exchange between multi-charged ions. This is an important reference data virtually inaccessible by other experimental methods. The rate coefficients of charge exchange are important for magnetic fusion in Tokamaks, for population inversion in the soft x-ray and VUV ranges, for ion storage devices, as well as for astrophysics (e.g., for the solar plasma and for determining the physical state of planetary nebulae).

  3. Quantum and semiclassical spin networks: from atomic and molecular physics to quantum computing and gravity

    NASA Astrophysics Data System (ADS)

    Aquilanti, Vincenzo; Bitencourt, Ana Carla P.; Ferreira, Cristiane da S.; Marzuoli, Annalisa; Ragni, Mirco

    2008-11-01

    The mathematical apparatus of quantum-mechanical angular momentum (re)coupling, developed originally to describe spectroscopic phenomena in atomic, molecular, optical and nuclear physics, is embedded in modern algebraic settings which emphasize the underlying combinatorial aspects. SU(2) recoupling theory, involving Wigner's 3nj symbols, as well as the related problems of their calculations, general properties, asymptotic limits for large entries, nowadays plays a prominent role also in quantum gravity and quantum computing applications. We refer to the ingredients of this theory—and of its extension to other Lie and quantum groups—by using the collective term of 'spin networks'. Recent progress is recorded about the already established connections with the mathematical theory of discrete orthogonal polynomials (the so-called Askey scheme), providing powerful tools based on asymptotic expansions, which correspond on the physical side to various levels of semi-classical limits. These results are useful not only in theoretical molecular physics but also in motivating algorithms for the computationally demanding problems of molecular dynamics and chemical reaction theory, where large angular momenta are typically involved. As for quantum chemistry, applications of these techniques include selection and classification of complete orthogonal basis sets in atomic and molecular problems, either in configuration space (Sturmian orbitals) or in momentum space. In this paper, we list and discuss some aspects of these developments—such as for instance the hyperquantization algorithm—as well as a few applications to quantum gravity and topology, thus providing evidence of a unifying background structure.

  4. A latest developed all permanent magnet ECRIS for atomic physics research at IMP

    SciTech Connect

    Sun, L.T.; Zhao, H.W.; Zhang, Z.M.; Wang, H.; Ma, B.H.; Li, J.Y.; Zhang, X.Z.; Feng, Y.C.; Guo, X.H.; Li, X.X.; Ma, X.W.; Song, M.T.; Zhan, W.L.

    2006-03-15

    Electron cyclotron resonance (ECR) ion sources have been used for atomic physics research for a long time. With the development of atomic physics research in the Institute of Modern Physics (IMP), additional high performance experimental facilities are required. A 300 kV high voltage (HV) platform has been under construction since 2003, and an all permanent magnet ECR ion source is supposed to be put on the platform. Lanzhou all permanent magnet ECR ion source No. 2 (LAPECR2) is a latest developed all permanent magnet ECRIS. It is a 900 kg weight and null-set 650 mmx562 mm outer dimension (magnetic body) ion source. The injection magnetic field of the source is 1.28 T and the extraction magnetic field is 1.07 T. This source is designed to be running at 14.5 GHz. The high magnetic field inside the plasma chamber enables the source to give good performances at 14.5 GHz. LAPECR2 source is now under commissioning in IMP. In this article, the typical parameters of the source LAPECR2 are listed, and the typical results of the preliminary commissioning are presented.

  5. The role of atomic and molecular physics for dissipative divertor operation in helium and deuterium plasmas

    NASA Astrophysics Data System (ADS)

    Canik, J. M.

    2016-10-01

    Recent experiments in DIII-D helium plasmas are examined to resolve the role of atomic and molecular physics in major discrepancies between experiment and modeling of dissipative divertor operation. Helium operation removes the complicated molecular processes of deuterium plasmas that are a prime candidate for the inability of standard fluid models (SOLPS, UEDGE) to reproduce dissipative divertor operation, primarily the consistent under-prediction of radiated power. With helium fueling, a high-recycling divertor was established with divertor densities increasing to ne,div >= 3 ×1020m-3 and temperatures decreasing to Te,div <= 2 eV as measured by divertor Thomson scattering (DTS). The electron pressure, pe , div decreased gradually with increasing density to less than 30% of the low density value. However, the ion flux to the divertor target did not decrease until the highest densities and lowest temperatures, Te,div <= 2 eV. In contrast, with deuterium operation, increasing density leads to a rapid transition from Te,div >= 10 eV to Te,div <= 3 eV, though both pe , div and ion flux do not decrease until Te,div <= 2 eV. These differences indicate an important role for molecular and atomic physics in the dynamics of divertor dissipation. Initial SOLPS modeling has reproduced ne and Te profiles at the midplane and divertor target, as well as the spatial structure of radiation patterns measured in moderate density helium plasmas. However, the modeled divertor radiation is less than measured, similar to deuterium simulations, suggesting processes more universal than species-specific atomic or molecular physics may be the source of radiation deficit. Detailed assessments of ne, Te profiles in the divertor volume, uniquely determined at DIII-D using DTS, are made along with analysis of measured and modeled line radiation to shed more light on these intriguing findings. Supported by the US DOE under DE-AC05-00OR22725.

  6. Sixteenth International Conference on the physics of electronic and atomic collisions

    SciTech Connect

    Dalgarno, A.; Freund, R.S.; Lubell, M.S.; Lucatorto, T.B.

    1989-01-01

    This report contains abstracts of papers on the following topics: photons, electron-atom collisions; electron-molecule collisions; electron-ion collisions; collisions involving exotic species; ion- atom collisions, ion-molecule or atom-molecule collisions; atom-atom collisions; ion-ion collisions; collisions involving rydberg atoms; field assisted collisions; collisions involving clusters and collisions involving condensed matter.

  7. Several atomic-physics issues connected with the use of neutral beams in fusion experiments

    SciTech Connect

    Post, D.E.; Grisham, L.R.; Fonck, R.J.

    1982-08-01

    Energetic neutral beams are used for heating and diagnostics in present magnetic fusion experiments. They are also being considered for use in future large experiments. Atomic physics issues are important for both the production of the neutral beams and the interaction of the beams and the plasma. Interest in neutral beams based on negative hydrogen ions is growing, largely based on advances in producing high current ion sources. An extension of the negative ion approach has been the suggestion to use negative ions of Z > 1 elements, such as carbon and oxygen, to form high power neutral beams for plasma heating.

  8. Application of the Finite Element Method in Atomic and Molecular Physics

    NASA Technical Reports Server (NTRS)

    Shertzer, Janine

    2007-01-01

    The finite element method (FEM) is a numerical algorithm for solving second order differential equations. It has been successfully used to solve many problems in atomic and molecular physics, including bound state and scattering calculations. To illustrate the diversity of the method, we present here details of two applications. First, we calculate the non-adiabatic dipole polarizability of Hi by directly solving the first and second order equations of perturbation theory with FEM. In the second application, we calculate the scattering amplitude for e-H scattering (without partial wave analysis) by reducing the Schrodinger equation to set of integro-differential equations, which are then solved with FEM.

  9. Nuclear-spin-independent short-range three-body physics in ultracold atoms.

    PubMed

    Gross, Noam; Shotan, Zav; Kokkelmans, Servaas; Khaykovich, Lev

    2010-09-03

    We investigate three-body recombination loss across a Feshbach resonance in a gas of ultracold 7Li atoms prepared in the absolute ground state and perform a comparison with previously reported results of a different nuclear-spin state [N. Gross, Phys. Rev. Lett. 103, 163202 (2009)]. We extend the previously reported universality in three-body recombination loss across a Feshbach resonance to the absolute ground state. We show that the positions and widths of recombination minima and Efimov resonances are identical for both states which indicates that the short-range physics is nuclear-spin independent.

  10. Spectroscopy of antiprotonic helium atoms and its contribution to the fundamental physical constants

    PubMed Central

    Hayano, Ryugo S.

    2010-01-01

    Antiprotonic helium atom, a metastable neutral system consisting of an antiproton, an electron and a helium nucleus, was serendipitously discovered, and has been studied at CERN’s antiproton decelerator facility. Its transition frequencies have recently been measured to nine digits of precision by laser spectroscopy. By comparing these experimental results with three-body QED calculations, the antiproton-to-electron massratio was determined as 1836.152674(5). This result contributed to the CODATA recommended values of the fundamental physical constants. PMID:20075605

  11. The Atomic Era: A new interdisciplinary course combining physics, the humanities and the social sciences

    NASA Astrophysics Data System (ADS)

    Carstens-Wickham, Belinda

    2001-05-01

    Southern Illinois University Edwardsville won funding from the federal interagency competition, Leadership Opportunity in Science and Humanities Education, which supported interdisciplinary courses combining the natural sciences and the humanities. The author analyses her experiences developing a very successful and popular interdisciplinary course, entitled The Atomic Era, which features a unique combination of physics, sociology and German studies taught jointly by a Physicist, a Sociologist and a Germanist. The objectives of the course, the laboratories and demonstrations, instructional goals, assignments, organization, testing, student and faculty assessment, expenses and the special challenges of coordinating three faculty members and a wide variety of topics and perspectives are addressed and analysed.

  12. Ab Initio Study on Atomic Structures and Physical Properties of CdSe Quantum Nanodots

    DTIC Science & Technology

    2009-11-25

    CdSe quantum dots , with magic number (( CdSe )13, ( CdSe )19, ( CdSe )33 and ( CdSe )34 ). Effects of organic ligand binding on the stability of CdSe as well...calculations of optical absorption spectra for CdSe quantum dots , with magic number (( CdSe )13, ( CdSe )19, ( CdSe )33 and ( CdSe )34 ), have been calculated in...1 AOARD-08-4037 Title of Proposed Project: Ab initio study on atomic structures and physical

  13. ELASR - An electrostatic storage ring for atomic and molecular physics at KACST

    NASA Astrophysics Data System (ADS)

    El Ghazaly, Mohamed O. A.

    A new ELectrostAtic Storage Ring (ELASR) has been designed and built at the King Abdulaziz City for Science and Technology (KACST), in Riyadh, Saudi Arabia. It was developed to be the core of a new storage ring laboratory for atomic and molecular physics at KACST. ELASR follows the standard design of the pioneering storage ring ELISA and it thereby features a racetrack single-bend shaped ring. Complementary simulation code packages were used to work out the design under the requirements of the projected experiments. This paper reports a short description of the ELASR storage ring through an overview of its design and construction.

  14. Atomic layer deposition of metal oxide patterns on nonwoven fiber mats using localized physical compression.

    PubMed

    Sweet, William J; Oldham, Christopher J; Parsons, Gregory N

    2014-06-25

    Patterning is an essential part of many industrial processes from printing to semiconductor manufacturing. In this work, we demonstrate a new method to pattern and selectively coat nonwoven textiles by atomic layer deposition (ALD) using compressive mask patterning. A physical mask combined with mechanical compression allows lateral definition and fidelity of the ALD coating to be controlled. We produce features of several sizes on different nonwoven fiber materials and demonstrate the ability to limit diffusion effects to within <200 μm of the pattern edge. Lateral and vertical penetration of reactive growth species into nonwoven mats is investigated by plan-view and cross-sectional imaging. Vertical growth is also analyzed by imaging coating depth into fiber mat stacks. We develop a fully quantitative transport model that describes well the effect of fiber structure and mechanical compression on the extent of coating under the physical mask. This method could be implemented for high-volume patterning for applications including flexible electronics.

  15. Physics of our Days: Cooling and thermometry of atomic Fermi gases

    NASA Astrophysics Data System (ADS)

    Onofrio, R.

    2017-02-01

    We review the status of cooling techniques aimed at achieving the deepest quantum degeneracy for atomic Fermi gases. We first discuss some physics motivations, providing a quantitative assessment of the need for deep quantum degeneracy in relevant physics cases, such as the search for unconventional superfluid states. Attention is then focused on the most widespread technique to reach deep quantum degeneracy for Fermi systems, sympathetic cooling of Bose-Fermi mixtures, organizing the discussion according to the specific species involved. Various proposals to circumvent some of the limitations on achieving the deepest Fermi degeneracy, and their experimental realizations, are then reviewed. Finally, we discuss the extension of these techniques to optical lattices and the implementation of precision thermometry crucial to the understanding of the phase diagram of classical and quantum phase transitions in Fermi gases.

  16. Quantum simulation of many-body physics with neutral atoms, molecules, and ions

    NASA Astrophysics Data System (ADS)

    Foss-Feig, Michael

    Real materials are extremely complicated, and any attempt to understand their bulk properties must begin with the appropriate choice of an idealized model, or Hamiltonian. There are many situations where such models have furnished a decisive understanding of complex quantum phenomena, such as BCS superconductivity and quantum magnetism. There are also cases, for instance the unconventional superconductivity of doped cuprates or heavy-fermion metals, where even the simplest conceivable models are intractable to current theoretical techniques. A promising route toward understanding the physics of such models is to simulate them directly with a highly controlled quantum system. Ultracold neutral atoms, polar molecules, and ions are in many ways ideally suited to this task. In this thesis, we emphasize how the unique features of particular atomic and molecular systems can be leveraged to access interesting physics in experimentally feasible temperature regimes. In chapter 3, we consider prospects for simulation of the Kondo lattice model using alkaline-earth atoms. In particular, we show how groundstate properties—for instance anomalous mass enhancement—can be probed by looking at far-from equilibrium dynamics, which are a standard diagnostic tool in ultracold atom experiments. Chapter 4 describes a realistic implementation of a bosonic version of the Kondo lattice model, and we show how the Kondo interaction qualitatively changes the superfluid to Mott insulator phase transition. Chapters 5, 6, and 7 are unified through an attempt to understand the effects of dissipation in many-body quantum systems. In chapter 5, our goal is mainly to understand the detrimental effects of two-body reactive collisions on dipolar molecules in a 3D optical lattice. Chapter 6 takes a rather different perspective, and shows that this type of loss naturally induces quantum correlations in the steady state of reactive fermionic molecules or alkaline earth atoms. In chapter 7, we develop

  17. Atomic physics and synchrotron radiation: The production and accumulation of highly charged ions

    SciTech Connect

    Johnson, B.M.; Meron, M.; Agagu, A.; Jones, K.W.

    1986-01-01

    Synchrotron radiation can be used to produce highly-charged ions, and to study photoexcitation and photoionization for ions of virtually any element in the periodic table. To date, with few exceptions, atomic physics studies have been limited to rare gases and a few metal vapors, and to photoexcitation energies in the VUV region of the electromagnetic spectrum. These limitations can now be overcome using photons produced by high-brightness synchrotron storage rings, such as the x-ray ring at the National Synchrotron Light Source (NSLS) at Brookhaven. Furthermore, calculations indicate that irradiation of an ion trap with an intense energetic photon beam will result in a viable source of highly-charged ions that can be given the name PHOBIS: the PHOton Beam Ion Source. Promising results, which encourage the wider systematic use of synchrotron radiation in atomic physics research, have been obtained in recent experiments on VUV photoemission and the production and storage of multiply-charged ions. 26 refs., 4 figs., 1 tab.

  18. The effect of atomic mass on the physical spatial resolution in EBSD.

    PubMed

    Chen, Delphic; Kuo, Jui-Chao

    2013-08-01

    In this study, bicrystals of silver (Ag) and aluminum (Al) were used to investigate the physical spatial resolution of the electron backscatter diffraction system combining a digital image correlation method. Furthermore, the effect of the accelerating voltage and probe current was investigated on the physical spatial resolution of the lateral and longitudinal resolutions for Ag and Al, respectively. The lateral and longitudinal resolutions show high dependency on the accelerating voltage for a low atomic mass material of Al, In addition, these are almost independent of the accelerating voltage for a high atomic mass material of Ag. Moreover, the probe current does not play any role on both the lateral and longitudinal resolutions. The best lateral resolutions for Al and Ag are 40.5 and 12.1 nm at 10 kV and 1 nA, respectively. The best longitudinal resolutions of 23.2 and 80 nm were obtained at 10 kV and 1 nA for Al and Ag, respectively.

  19. The Influence of Physical and Physiological Cues on Atomic Force Microscopy-Based Cell Stiffness Assessment

    PubMed Central

    Chiou, Yu-Wei; Lin, Hsiu-Kuan; Tang, Ming-Jer; Lin, Hsi-Hui; Yeh, Ming-Long

    2013-01-01

    Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM)-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young’s modulus (Eeff) relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues. PMID:24194882

  20. The influence of physical and physiological cues on atomic force microscopy-based cell stiffness assessment.

    PubMed

    Chiou, Yu-Wei; Lin, Hsiu-Kuan; Tang, Ming-Jer; Lin, Hsi-Hui; Yeh, Ming-Long

    2013-01-01

    Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM)-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young's modulus (E(eff)) relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues.

  1. Relativistic Momentum-Space Equations with Applications to Atomic and Elementary Particle Physics

    NASA Astrophysics Data System (ADS)

    Hardekopf, Eugene Edward

    Relativistic equal-time wave equations obtained from field theory which describe bound states of N Dirac particles inevitably involve free or external-field positive -energy projection operators (LAMDA)(,+)(i). For N > 2 these operators are vital if the equations are to admit normaliz- able solutions. Such equations have been used in the past to obtain relativistic corrections to simple atomic systems, and to provide a theoretical basis for the Dirac-Hartree-Fock type of equations for many-electron atoms. These equations also find applications in ele- mentary particle physics in describing bound states of quarks. Here we initiate a numerical study of such equations, avoiding an expan- sion in powers of v/c. We work in momentum space, where the free projection operators are simple functions of (')p. We describe tech- niques for finding the eigenvalues and eigenfunctions of H(,+)(1,2) = h(,D)(1) + h(,D)(2) + (LAMDA)(,++)V(LAMDA)(,++) where h(,D)(i) is the free Dirac Hamiltonian and V is a local potential with either a (VBAR)(')r(,1)-(')r(,2)(VBAR)('-1) singularity in the case of atomic systems, or a (VBAR)(')r(,1)-(')r(,2)(VBAR) behavior plus a Coulomb-like singular- ity in the case of bound quarks. Results are presented for both pure Coulomb and a Coulomb plus Breit potential for the atomic case, and for a pure Lorentz scalar in the linear potential case. In the atomic case a wide range of m(,1)/m(,2) and coupling strength (gamma) is studied and the m(,2) = (INFIN) limit is compared with the Dirac equation. The magni- tude of level shifts associated with virtual pair production in such two-body systems is discussed. For intermediate values of (gamma) a com- parison is made between the numerical results and those of pertur- bation theory. We find that there can often be large corrections to perturbative results even for not terribly large values of v/c. We also study the strong coupling limit and find the value (gamma)(,max) for which the lowest-lying bound state

  2. Atomic physics and quantum optics using superconducting circuits: from the Dynamical Casimir effect to Majorana fermions

    NASA Astrophysics Data System (ADS)

    Nori, Franco

    2012-02-01

    This talk will present an overview of some of our recent results on atomic physics and quantum optics using superconducting circuits. Particular emphasis will be given to photons interacting with qubits, interferometry, the Dynamical Casimir effect, and also studying Majorana fermions using superconducting circuits.[4pt] References available online at our web site:[0pt] J.Q. You, Z.D. Wang, W. Zhang, F. Nori, Manipulating and probing Majorana fermions using superconducting circuits, (2011). Arxiv. J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in a superconducting coplanar waveguide, Phys. Rev. Lett. 103, 147003 (2009). [0pt] J.R. Johansson, G. Johansson, C.M. Wilson, F. Nori, Dynamical Casimir effect in superconducting microwave circuits, Phys. Rev. A 82, 052509 (2010). [0pt] C.M. Wilson, G. Johansson, A. Pourkabirian, J.R. Johansson, T. Duty, F. Nori, P. Delsing, Observation of the Dynamical Casimir Effect in a superconducting circuit. Nature, in press (Nov. 2011). P.D. Nation, J.R. Johansson, M.P. Blencowe, F. Nori, Stimulating uncertainty: Amplifying the quantum vacuum with superconducting circuits, Rev. Mod. Phys., in press (2011). [0pt] J.Q. You, F. Nori, Atomic physics and quantum optics using superconducting circuits, Nature 474, 589 (2011). [0pt] S.N. Shevchenko, S. Ashhab, F. Nori, Landau-Zener-Stuckelberg interferometry, Phys. Reports 492, 1 (2010). [0pt] I. Buluta, S. Ashhab, F. Nori. Natural and artificial atoms for quantum computation, Reports on Progress in Physics 74, 104401 (2011). [0pt] I.Buluta, F. Nori, Quantum Simulators, Science 326, 108 (2009). [0pt] L.F. Wei, K. Maruyama, X.B. Wang, J.Q. You, F. Nori, Testing quantum contextuality with macroscopic superconducting circuits, Phys. Rev. B 81, 174513 (2010). [0pt] J.Q. You, X.-F. Shi, X. Hu, F. Nori, Quantum emulation of a spin system with topologically protected ground states using superconducting quantum circuit, Phys. Rev. A 81, 063823 (2010).

  3. Influence of Halide Solutions on Collagen Networks: Measurements of Physical Properties by Atomic Force Microscopy

    PubMed Central

    Kempe, André; Lackner, Maximilian

    2016-01-01

    The influence of aqueous halide solutions on collagen coatings was tested. The effects on resistance against indentation/penetration on adhesion forces were measured by atomic force microscopy (AFM) and the change of Young's modulus of the coating was derived. Comparative measurements over time were conducted with halide solutions of various concentrations. Physical properties of the mesh-like coating generally showed large variability. Starting with a compact set of physical properties, data disperse after minutes. A trend of increase in elasticity and permeability was found for all halide solutions. These changes were largest in NaI, displaying a logical trend with ion size. However a correlation with concentration was not measured. Adhesion properties were found to be independent of mechanical properties. The paper also presents practical experience for AFM measurements of soft tissue under liquids, particularly related to data evaluation. The weakening in physical strength found after exposure to halide solutions may be interpreted as widening of the network structure or change in the chemical properties in part of the collagen fibres (swelling). In order to design customized surface coatings at optimized conditions also for medical applications, halide solutions might be used as agents with little impact on the safety of patients. PMID:27721994

  4. The AMS Measurements and Its Applications in Nuclear Physics at China Institute of Atomic Energy (CIAE)

    SciTech Connect

    Jiang Shan; Shen Hongtao; He Ming; Dong Kejun; He Guozhu; Wang Xianggao; Yuan Jian; Wang Wei; Wu Shaoyong; Ruan Xiangdong; Wu Weimin

    2010-05-12

    Accelerator Mass Spectrometry (AMS), initiated in late 1970s at McMaster university based on the accelerator and detector technique, has long been applied in the studies on archaeology, geology, and cosmology, as a powerful tool for isotope dating. The advantages of AMS in the analysis of rare nuclides by direct counting of the atoms, small sample size and relatively free from the interferences of molecular ions have been well documented. This paper emphasizes that AMS can not only be used for archaeology, geology, environment, biology and so on, but also served as a unique tool for nuclear physics research. In this paper, the determination of the half-lives of {sup 79}Se, the measurements of the cross-sections of {sup 93}Nb(n,2n){sup 92g}Nb and {sup 238}U(n,3n){sup 236}U reactions, the detection and determination of ultratrace impurities in neutrino detector materials, and the measurement of the fission product nuclide {sup 126}Sn, are to be introduced, as some of examples of AMS applications in nuclear research conducted in AMS lab of China Institute of Atomic Energy. Searching for superheavy nuclides by using AMS is being planned.

  5. The AMS Measurements and Its Applications in Nuclear Physics at China Institute of Atomic Energy (CIAE)

    NASA Astrophysics Data System (ADS)

    Jiang, Shan; Shen, Hongtao; He, Ming; Ruan, Xiangdong; Wu, Weimin; Dong, Kejun; He, Guozhu; Wang, Xianggao; Yuan, Jian; Wang, Wei; Wu, Shaoyong

    2010-05-01

    Accelerator Mass Spectrometry (AMS), initiated in late 1970s at McMaster university based on the accelerator and detector technique, has long been applied in the studies on archaeology, geology, and cosmology, as a powerful tool for isotope dating. The advantages of AMS in the analysis of rare nuclides by direct counting of the atoms, small sample size and relatively free from the interferences of molecular ions have been well documented. This paper emphasizes that AMS can not only be used for archaeology, geology, environment, biology and so on, but also served as a unique tool for nuclear physics research. In this paper, the determination of the half-lives of 79Se, the measurements of the cross-sections of 93Nb(n,2n)92gNb and 238U(n,3n)236U reactions, the detection and determination of ultratrace impurities in neutrino detector materials, and the measurement of the fission product nuclide 126Sn, are to be introduced, as some of examples of AMS applications in nuclear research conducted in AMS lab of China Institute of Atomic Energy. Searching for superheavy nuclides by using AMS is being planned.

  6. Making custom fiber lasers for use in an atomic physics experiment

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Cameron, Garnet; Nault, Kyla; Shiner, David

    2016-05-01

    Fiber lasers can be a reasonable choice for a laser source in atomic physics. Our particular applications involve the optical pumping and in some applications cooling of various transitions in atomic helium. Doped fiber with emission at the required wavelengths is necessary. Readily available fiber and approximate wavelength emission ranges include Yb (990 - 1150 nm), Er/Yb (1530 - 1625 nm) and Th (1900 -2100 nm). High efficiency conversion of pump photons into stable single frequency laser emission at the required wavelength is the function of the fiber laser. A simple fiber laser cavity uses a short (~ few mm) fiber grating high reflector mirror, a doped fiber section for the laser cavity, and a long (~ few cm) fiber grating output coupler. To ensure reliable single frequency operation, the laser cavity length should be within 2-3 times the output grating length. However the cavity length must be long enough for round trip gains to compensate for the output mirror transmission loss. Efficiency can be maximized by avoiding fiber splices in the fiber laser cavity. This requires that the gratings be written into the doped fiber directly. In our previous designs, back coupling of the fiber laser into the pump laser contributes to instability and sometimes caused catastrophic pump failure. Current designs use a fiber based wavelength splitter (WDM) to study and circumvent this problem. Data will be presented on the fiber lasers at 1083 nm. Work on a Thulium 2057 nm fiber laser will also be discussed. This work is supported by NSF Grant # 1404498.

  7. A distributed, graphical user interface based, computer control system for atomic physics experiments

    NASA Astrophysics Data System (ADS)

    Keshet, Aviv; Ketterle, Wolfgang

    2013-01-01

    Atomic physics experiments often require a complex sequence of precisely timed computer controlled events. This paper describes a distributed graphical user interface-based control system designed with such experiments in mind, which makes use of off-the-shelf output hardware from National Instruments. The software makes use of a client-server separation between a user interface for sequence design and a set of output hardware servers. Output hardware servers are designed to use standard National Instruments output cards, but the client-server nature should allow this to be extended to other output hardware. Output sequences running on multiple servers and output cards can be synchronized using a shared clock. By using a field programmable gate array-generated variable frequency clock, redundant buffers can be dramatically shortened, and a time resolution of 100 ns achieved over effectively arbitrary sequence lengths.

  8. The Heidelberg test storage ring for heavy ions and its use for atomic physics

    SciTech Connect

    Schuch, R.

    1986-11-01

    A brief description of the Heavy-Ion Test Storage Ring (TSR) presently being built at the Max-Planck Institut in Heidelberg is given. It will be able to store ions injected from the tandem postaccelerator combination up to about 30 MeV/nucleon for a charge to mass ratio of 0.5. One of the main purposes of the TSR will be the study of electron cooling. Some atomic physics experiments are discussed using the electron cooling device which provides an electron-ion collision facility with good energy resolution and ion beams of high currents and low emittances. Here the possibilities for measurements of spontaneous and laser-induced radiative recombination and dielectronic recombination in the electron cooling section are discussed.

  9. United-Atom Discrete Molecular Dynamics of Proteins Using Physics-Based Potentials.

    PubMed

    Emperador, Agustí; Meyer, Tim; Orozco, Modesto

    2008-12-09

    We present a method for the efficient simulation of the equilibrium dynamics of proteins based on the well established discrete molecular dynamics algorithm, which avoids integration of Newton equations of motion at short time steps, allowing then the derivation of very large trajectories for proteins with a reduced computational cost. In the presented implementation we used an all heavy-atoms description of proteins, with simple potentials describing the conformational region around the experimental structure based on local physical interactions (covalent structure, hydrogen bonds, hydrophobic contacts, solvation, steric hindrance, and bulk dispersion interactions). The method shows a good ability to describe the flexibility of 33 diverse proteins in water as determined by atomistic molecular dynamics simulation and can be useful for massive simulation of proteins in crowded environments or for refinement of protein structure in large complexes.

  10. Navigating a Career in Science: from Experimental Atomic Physics to AGU

    NASA Astrophysics Data System (ADS)

    Killeen, T. L.

    2007-12-01

    Building and sustaining a satisfying career in the geosciences involves hard work, some luck, some pluck - and a lot off tenacity. In this presentation I will recount some lessons I learned - and am still learning - on my own path from a start in a graduate program in experimental atomic physics to my current position as president of the AGU and Director of the National Center for Atmospheric Research. The presentation will describe some of the scientific and science management contributions of which I am most proud - and some of the dead ends too. AGU, in particular, has been an excellent resource and venue for connecting with colleagues and following the evolution of dynamic fields of inquiry in the geosciences. AGU is still evolving and the presentation will also describe some of the current trends that make the Union such an interesting and valuable hub for our field.

  11. Design of heavy-ion APF-IH type linac for atomic physics and medical use

    NASA Astrophysics Data System (ADS)

    Hata, T.; Hattori, T.; Kashiwagi, H.; Takahashi, Y.; Yamamoto, K.; Matsui, S.; Dudu, D.; Osvath, E.; Vata, I.; Yamada, S.

    2002-04-01

    We have studied a compact heavy-ion linac for atomic physics and medical use. The design of the linac was based on using alternating-phase-focus (APF) and interdigital-H (IH) structures which give sufficient electric power efficiency. Thereby, it will be possible to design a small and high efficiency linac. The APF-IH linac was designed to accelerate ions from C 2+ to U 40+, from 30 to 300 keV/u and an operating frequency of 100 MHz. We made a half-scale cold model of this linac using orbit calculation and measured its RF characteristics. Then, we designed a APF-IH type linac using the results of the measurement.

  12. ATOMIC PHYSICS PROCESSES IMPORTANT TO THE UNDERSTANDING OF THE SCRAPE-OFF LAYER OF TOKAMAKS

    SciTech Connect

    WEST, W.P.; GOLDSMITH,; B. EVANS,T.E.; OLSON, R.J.

    2002-05-01

    The region between the well-confined plasma and the vessel walls of a magnetic confinement fusion research device, the scrape-off layer (SOL), is typically rich in atomic and molecular physics processes. The most advanced magnetic confinement device, the magnetically diverted tokamak, uses a magnetic separatrix to isolate the confinement zone (closed flux surfaces) from the edge plasma (open field lines). Over most of their length the open field lines run parallel to the separatrix, forming a thin magnetic barrier with the nearby vessel walls. In a poloidally-localized region, the open field lines are directed away from the separatrix and into the divertor, a region spatially separated from the separatrix where intense plasma wall interaction can occur relatively safely. Recent data from several tokamaks indicate that particle transport across the field lines of the SOL can be somewhat faster than previously thought. In these cases, the rate at which particles reach the vessel wall is comparable to the rate to the divertor from parallel transport. The SOL can be thin enough that the recycling neutrals and sputtered impurities from the wall may refuel or contaminate the confinement zone more efficiently than divertor plasma wall interaction. Just inside the SOL is a confinement barrier that produces a sharp pedestal in plasma density and temperature. Understanding neutral transport through the SOL and into the pedestal is key to understanding particle balance and particle and impurity exhaust. The SOL plasma is sufficiently hot and dense to excite and ionize neutrals. Ion and neutral temperatures are high enough that charge exchange between the neutrals and fuel and impurity ions is fast. Excitation of neutrals can be fast enough to lead to nonlinear behavior in charge exchange and ionization processes. In this paper the detailed atomic physics important to the understanding of the neutral transport through the SOL will be discussed.

  13. Improving the Physical Realism and Structural Accuracy of Protein Models by a Two-Step Atomic-Level Energy Minimization

    PubMed Central

    Xu, Dong; Zhang, Yang

    2011-01-01

    Most protein structural prediction algorithms assemble structures as reduced models that represent amino acids by a reduced number of atoms to speed up the conformational search. Building accurate full-atom models from these reduced models is a necessary step toward a detailed function analysis. However, it is difficult to ensure that the atomic models retain the desired global topology while maintaining a sound local atomic geometry because the reduced models often have unphysical local distortions. To address this issue, we developed a new program, called ModRefiner, to construct and refine protein structures from Cα traces based on a two-step, atomic-level energy minimization. The main-chain structures are first constructed from initial Cα traces and the side-chain rotamers are then refined together with the backbone atoms with the use of a composite physics- and knowledge-based force field. We tested the method by performing an atomic structure refinement of 261 proteins with the initial models constructed from both ab initio and template-based structure assemblies. Compared with other state-of-art programs, ModRefiner shows improvements in both global and local structures, which have more accurate side-chain positions, better hydrogen-bonding networks, and fewer atomic overlaps. ModRefiner is freely available at http://zhanglab.ccmb.med.umich.edu/ModRefiner. PMID:22098752

  14. Effects of Solution Physical Properties on Copper and Chromium Signals in Flame Atomic Absorption Spectrometry

    NASA Astrophysics Data System (ADS)

    Rocha, Fàbio R. P.; Nòbrega, Joaquim A.

    1996-10-01

    Instrumental techniques, such as flame atomic absorption spectrometry (FAAS), are frequently used in chemical analysis. Independently of the technique used, the chemical principles must be considered to assure that the analytical results are correct. In FAAS, the most critical step is the sample introduction, since solutions need to be converted in an aerosol (nebulization process) that should contain drops with suitable size to attain the flame. Solution physical properties, such as viscosity and surface tension, can severely affect the analytical signals. Solutions with high viscosity are less easily aspirated and the analyte mass that reach the flame is reduced. The surface tension of the solution affects the size of the drops generated by the nebulization process and can modify the quantity of analyte that attain the flame. This work describes an experiment that allow demonstrating the effects of viscosity and surface tension on analytical signals, using a set of copper solutions prepared in different concentrations of ethanol and chromium solutions prepared in surfactant (tetrapropylammonium bromide) medium. The experiment can be carried out in a 4 h laboratory class and is useful to demonstrate to undergraduate students the effects of samples physical properties on the analytical signals in FAAS.

  15. Finite Range Effects in Atomic and Nuclear Three-Body Physics

    NASA Astrophysics Data System (ADS)

    Shepard, James

    2009-05-01

    I examine effects of the finite range of the 2-body interaction on 3-body physics in the low energy limit where there has been much recent effort in understanding these phenomena using Effective Theories (ET's). I assume separable (SP) 2-body interactions -- widely used in nuclear 3-body calculations shortly after the crucial work of Faddeev fifty years ago -- which permit analytic solutions for the exact t-matrix which, eg, respect unitarity exactly. I compare these results with ``standard'' ET calculations in which incorporation of finite range effects is based on the Effective Range Expansion (ERE) of the 2-body on-shell scattering amplitude. We find that ET-ERE calculations for the quartet (spin=3/2) s-wave channel of neutron-deuteron elastic scattering disagree significantly from the the SP results in some cases. I discuss the origin and the significance of these discrepancies. I also discuss similar sets of calculations for cold, dilute atomic Bose gases. These provide a relatively simple means of reliably computing, eg, 3-body recombination coefficients while appropriately accounting for Efimov physics. I also discuss how these calculations can be adapted to treat certain many-body effects in Bose gases which might help in understanding, eg, the single quasi-particle dispersion relation as revealed by Bragg scattering experiments.

  16. Acquire an Bruker Dimension FastScanTM Atomic Force Microscope (AFM) for Materials, Physical and Biological Science Research and Education

    DTIC Science & Technology

    2016-04-14

    UU 14-04-2016 1-Jan-2015 31-Jan-2016 Final Report: Acquire an Bruker Dimension FastScanTM Atomic Force Microscope (AFM) for Materials, Physical and...published in non peer-reviewed journals: Final Report: Acquire an Bruker Dimension FastScanTM Atomic Force Microscope (AFM) for Materials, Physical and...the DOD HBCU/MI Instrumentation Award Regarding “Acquire an Bruker Dimension FastScan TM Atomic Force Microscope (AFM) for Materials, Physical

  17. Characterization of mussel H2A.Z.2: a new H2A.Z variant preferentially expressed in germinal tissues from Mytilus.

    PubMed

    Rivera-Casas, Ciro; González-Romero, Rodrigo; Vizoso-Vazquez, Ángel; Cheema, Manjinder S; Cerdán, M Esperanza; Méndez, Josefina; Ausió, Juan; Eirin-Lopez, Jose M

    2016-10-01

    Histones are the fundamental constituents of the eukaryotic chromatin, facilitating the physical organization of DNA in chromosomes and participating in the regulation of its metabolism. The H2A family displays the largest number of variants among core histones, including the renowned H2A.X, macroH2A, H2A.B (Bbd), and H2A.Z. This latter variant is especially interesting because of its regulatory role and its differentiation into 2 functionally divergent variants (H2A.Z.1 and H2A.Z.2), further specializing the structure and function of vertebrate chromatin. In the present work we describe, for the first time, the presence of a second H2A.Z variant (H2A.Z.2) in the genome of a non-vertebrate animal, the mussel Mytilus. The molecular and evolutionary characterization of mussel H2A.Z.1 and H2A.Z.2 histones is consistent with their functional specialization, supported on sequence divergence at promoter and coding regions as well as on varying gene expression patterns. More precisely, the expression of H2A.Z.2 transcripts in gonadal tissue and its potential upregulation in response to genotoxic stress might be mirroring the specialization of this variant in DNA repair. Overall, the findings presented in this work complement recent reports describing the widespread presence of other histone variants across eukaryotes, supporting an ancestral origin and conserved role for histone variants in chromatin.

  18. Introduction to the Contributions of A. Temkin and R. J. Drachman to Atomic Physics

    NASA Technical Reports Server (NTRS)

    Bhatia, A.K.

    2007-01-01

    Their work, as is the work of most atomic theorists, is concerned with solving the Schroedinger equation accurately for wave function in cases where there is no exact analytical solution. In particular, Temkin is associated with electron scattering from atoms and ions. When he started there already were a number of methods to study the scattering of electrons from atoms.

  19. Getting Physical with Your Chemistry: Mechanically Investigating Local Structure and Properties of Surfaces with the Atomic Force Microscope

    ERIC Educational Resources Information Center

    Heinz, William F.; Hoh, Jan H.

    2005-01-01

    Atomic force microscope (AFM) investigates mechanically the chemical properties of individual molecules, surfaces, and materials using suitably designed probes. The current state of the art of AFM in terms of imaging, force measurement, and sample manipulation and its application to physical chemistry is discussed.

  20. Getting Physical with Your Chemistry: Mechanically Investigating Local Structure and Properties of Surfaces with the Atomic Force Microscope

    ERIC Educational Resources Information Center

    Heinz, William F.; Hoh, Jan H.

    2005-01-01

    Atomic force microscope (AFM) investigates mechanically the chemical properties of individual molecules, surfaces, and materials using suitably designed probes. The current state of the art of AFM in terms of imaging, force measurement, and sample manipulation and its application to physical chemistry is discussed.

  1. The advanced light source at Lawrence Berkeley laboratory: a new tool for research in atomic physics

    NASA Astrophysics Data System (ADS)

    Schlachter, Alfred S.; Robinson, Arthur L.

    1991-04-01

    The Advanced Light Source, a third-generation national synchrotron-radiation facility now under construction at the Lawrence Berkeley Laboratory, is scheduled to begin serving qualified users across a broad spectrum of research areas in the spring of 1993. Based on a low-emittance electron storage ring optimized to operate at 1.5 GeV, the ALS will have 10 long straight sections available for insertion devices (undulators and wigglers) and 24 high-quality bend-magnet ports. The short pulse width (30-50 ps) will be ideal for time-resolved measurements. Undulators will generate high-brightness partially coherent soft X-ray and ultraviolet (XUV) radiation from below 10 eV to above 2 keV; this radiation is plane polarized. Wigglers and bend magnets will extend the spectrum by generating high fluxes of X-rays to photon energies above 10 keV. The ALS will have an extensive research program in which XUV radiation is used to study matter in all its varied gaseous, liquid, and solid forms. The high brightness will open new areas of research in the materials sciences, such as spatially resolved spectroscopy (spectromicroscopy), and in biology, such as X-ray microscopy with element-specific sensitivity; the high flux will allow measurements in atomic physics and chemistry to be made with tenuous gas-phase targets. Technological applications could include lithography and nano-fabrication.

  2. Protein model refinement using an optimized physics-based all-atom force field.

    PubMed

    Jagielska, Anna; Wroblewska, Liliana; Skolnick, Jeffrey

    2008-06-17

    One of the greatest challenges in protein structure prediction is the refinement of low-resolution predicted models to high-resolution structures that are close to the native state. Although contemporary structure prediction methods can assemble the correct topology for a large fraction of protein domains, such approximate models are often not of the resolution required for many important applications, including studies of reaction mechanisms and virtual ligand screening. Thus, the development of a method that could bring those structures closer to the native state is of great importance. We recently optimized the relative weights of the components of the Amber ff03 potential on a large set of decoy structures to create a funnel-shaped energy landscape with the native structure at the global minimum. Such an energy function might be able to drive proteins toward their native structure. In this work, for a test set of 47 proteins, with 100 decoy structures per protein that have a range of structural similarities to the native state, we demonstrate that our optimized potential can drive protein models closer to their native structure. Comparing the lowest-energy structure from each trajectory with the starting decoy, structural improvement is seen for 70% of the models on average. The ability to do such systematic structural refinements by using a physics-based all-atom potential represents a promising approach to high-resolution structure prediction.

  3. A physical approach to reduce nonspecific adhesion in molecular recognition atomic force microscopy.

    PubMed

    Willemsen, O H; Snel, M M; Kuipers, L; Figdor, C G; Greve, J; De Grooth, B G

    1999-02-01

    Atomic force microscopy is one of the few techniques that allow analysis of biological recognition processes at the single-molecule level. A major limitation of this approach is the nonspecific interaction between the force sensor and substrate. We have modeled the nonspecific interaction by looking at the interaction potential between a conical Si3N4 tip with a spherical end face and a mica surface in solution, using DLVO (Derjaguin, Landau, Verwey, Overbeek) theory and numerical calculations. Insertion of the tip-sample potential in a simulation of an approach-retract cycle of the cantilever gives the well-known force-distance curve. Simulating a force-distance curve at low salt concentration predicts a discrete hopping of the tip, caused by thermal fluctuations. This hopping behavior was observed experimentally and gave rise to a novel approach to making measurements in adhesion mode that essentially works in the repulsive regime. The distance between tip and sample will still be small enough to allow spacer-involved specific interactions, and the percentage of nonspecific interactions of the bare tip with the mica is minimized. We have validated this physical model by imaging intercellular adhesion molecule 1 (ICAM-1) antigen with a tip functionalized with anti-ICAM-1 antibody. The measurement demonstrated that a significant decrease in the number of nonspecific interactions was realized, and the topographical image quality and the specific bonding capability of the tip were not affected.

  4. Physics-based all-atom modeling of RNA energetics and structure.

    PubMed

    Smith, Louis G; Zhao, Jianbo; Mathews, David H; Turner, Douglas H

    2017-09-01

    The database of RNA sequences is exploding, but knowledge of energetics, structures, and dynamics lags behind. All-atom computational methods, such as molecular dynamics, hold promise for closing this gap. New algorithms and faster computers have accelerated progress in improving the reliability and accuracy of predictions. Currently, the methods can facilitate refinement of experimentally determined nuclear magnetic resonance and x-ray structures, but are 'unreliable' for predictions based only on sequence. Much remains to be discovered, however, about the many molecular interactions driving RNA folding and the best way to approximate them quantitatively. The large number of parameters required means that a wide variety of experimental results will be required to benchmark force fields and different approaches. As computational methods become more reliable and accessible, they will be used by an increasing number of biologists, much as x-ray crystallography has expanded. Thus, many fundamental physical principles underlying the computational methods are described. This review presents a summary of the current state of molecular dynamics as applied to RNA. It is designed to be helpful to students, postdoctoral fellows, and faculty who are considering or starting computational studies of RNA. WIREs RNA 2017, 8:e1422. doi: 10.1002/wrna.1422. © 2017 Wiley Periodicals, Inc.

  5. Atomic and molecular physics of plasma-based environmental technologies for abatement of volatile organic compounds

    SciTech Connect

    Penetrante, B.M.; Hsiao, M.C.; Bardsley, J.N.; Merritt, B.T.; Vogtlin, G.E.; Kuthi, A.; Burkhart, C.P.; Bayless, J.R.

    1996-08-01

    Non-thermal plasma techniques represent a new generation of air emission control technology that potentially could treat large-volume emissions containing dilute concentrations of volatile organic compounds (VOCs). In order to apply non-thermal plasmas in an industrial scale, it is important to establish the electrical power requirements and byproducts of the process. There is a need for reliable data concerning the primary decomposition mechanisms and subsequent chemical kinetics associated with non-thermal processing of VOCs. There are many basic atomic and molecular physics issues that are essential in evaluating the economic performance of non- thermal plasma reactors. These studies are important in understanding how the input electrical power is dissipated in the plasma and how efficiently it is converted to the production of the plasma species (radicals, ions, or electrons) responsible for the decomposition of the VOCs. This paper will present results from the basic experimental and theoretical studies aimed at identifying the reaction mechanisms responsible for the primary decomposition of various types of VOCs.

  6. Folding peptides and proteins with all-atom physics: methods and applications

    NASA Astrophysics Data System (ADS)

    Shell, M. Scott

    2008-03-01

    Computational methods offer powerful tools for investigating proteins and peptides at the molecular-level; however, it has proven challenging to reproduce the long time scale folding processes of these molecules at a level that is both faithful to the atomic driving forces and attainable with modern commodity cluster computing. Alternatively, the past decade has seen significant progress in using bioinformatics-based approaches to infer the three dimensional native structures of proteins, drawing upon extensive knowledge databases of known protein structures [1]. These methods work remarkably well when a homologous protein can be found to provide a structural template for a candidate sequence. However, in cases where homology to database proteins is low, where the folding pathway is of interest, or where conformational flexibility is substantial---as in many emerging protein and peptide technologies---bioinformatics methods perform poorly. There is therefore great interest in seeing purely physics-based approaches succeed. We discuss a purely physics-based, database-free folding method, relying on proper thermal sampling (replica exchange molecular dynamics) and molecular potential energy functions. In order to surmount the tremendous computational demands of all-atom folding simulations, our approach implements a conformational search strategy based on a putative protein folding mechanism called zipping and assembly [2-4]. That is, we explicitly seek out potential folding pathways inferred from short simulations, and iteratively pursue all such routes by coaxing a polypeptide chain along them. The method is called the Zipping and Assembly Method (ZAM) and it works in two parts: (1) the full polypeptide chain is broken into small fragments that are first simulated independently and then successively re-assembled into larger segments with further sampling, and (2) consistently stable structure in fragments is detected and locked into place, in order to avoid re

  7. Cold-atom physics using ultrathin optical fibers: light-induced dipole forces and surface interactions.

    PubMed

    Sagué, G; Vetsch, E; Alt, W; Meschede, D; Rauschenbeutel, A

    2007-10-19

    The strong evanescent field around ultrathin unclad optical fibers bears a high potential for detecting, trapping, and manipulating cold atoms. Introducing such a fiber into a cold-atom cloud, we investigate the interaction of a small number of cold cesium atoms with the guided fiber mode and with the fiber surface. Using high resolution spectroscopy, we observe and analyze light-induced dipole forces, van der Waals interaction, and a significant enhancement of the spontaneous emission rate of the atoms. The latter can be assigned to the modification of the vacuum modes by the fiber.

  8. Effects of the ether oxygen atom in alkyl side chains on the physical properties of piperidinium ionic liquids.

    PubMed

    Nokami, T; Yamashita, T; Komura, T; Handa, N; Shimizu, M; Yamaguchi, K; Domi, Y; Usui, H; Sakaguchi, H; Itoh, T

    2017-09-21

    Various types of piperidinium ionic liquids (ILs) equipped with an oxygen atom-containing alkyl side chain on the positively charged nitrogen atom were systematically synthesized and their physical properties investigated. The thermal stability, viscosity, electrochemical window, and ion conductivity were influenced significantly by changing the position of the oxygen atom in the alkyl chain. Although the lowest viscosity was recorded for 1-((2-methoxyethoxy)methyl)-1-methylpiperidin-1-ium bis(trifluoromethylsulfonyl)amide ([PP1MEM][Tf2N]), 1-methyl-1-(2-propoxyethyl)piperidin-1-ium bis(trifluoromethylsulfonyl)amide ([PP1PE][Tf2N]) can be recommended as the best IL as an electrolyte due to its low viscosity and high thermal and electrochemical stability among the seven ILs tested.

  9. Physical Construction of the Chemical Atom: Is It Convenient to Go All the Way Back?

    ERIC Educational Resources Information Center

    Izquierdo-Aymerich, Merce; Aduriz-Bravo, Agustin

    2009-01-01

    In this paper we present an analysis of chemistry texts (mainly textbooks) published during the first half of the 20th century. We show the evolution of the explanations therein in terms of atoms and of atomic structure, when scientists were interpreting phenomena as evidence of the discontinuous, corpuscular structure of matter. In this process…

  10. Atoms and Molecules. Physical Science in Action[TM]. Schlessinger Science Library. [Videotape].

    ERIC Educational Resources Information Center

    2000

    There are more than 20 million known substances in the universe, and they are all made of the same basic ingredients--atoms and molecules. In this fun and engaging program, kids will learn about the three main subatomic particles--protons, neutrons and electrons--as well as the forces that keep atoms and molecules together. They'll discover how…

  11. Atoms and Molecules. Physical Science in Action[TM]. Schlessinger Science Library. [Videotape].

    ERIC Educational Resources Information Center

    2000

    There are more than 20 million known substances in the universe, and they are all made of the same basic ingredients--atoms and molecules. In this fun and engaging program, kids will learn about the three main subatomic particles--protons, neutrons and electrons--as well as the forces that keep atoms and molecules together. They'll discover how…

  12. Physical Construction of the Chemical Atom: Is It Convenient to Go All the Way Back?

    ERIC Educational Resources Information Center

    Izquierdo-Aymerich, Merce; Aduriz-Bravo, Agustin

    2009-01-01

    In this paper we present an analysis of chemistry texts (mainly textbooks) published during the first half of the 20th century. We show the evolution of the explanations therein in terms of atoms and of atomic structure, when scientists were interpreting phenomena as evidence of the discontinuous, corpuscular structure of matter. In this process…

  13. Atomic physics with hard X-rays from high brilliance synchrotron light sources

    SciTech Connect

    Southworth, S.; Gemmell, D.

    1996-08-01

    A century after the discovery of x rays, the experimental capability for studying atomic structure and dynamics with hard, bright synchrotron radiation is increasing remarkably. Tempting opportunities arise for experiments on many-body effects, aspects of fundamental photon-atom interaction processes, and relativistic and quantum-electrodynamic phenomena. Some of these possibilities are surveyed in general terms.

  14. Emulating solid-state physics with a hybrid system of ultracold ions and atoms.

    PubMed

    Bissbort, U; Cocks, D; Negretti, A; Idziaszek, Z; Calarco, T; Schmidt-Kaler, F; Hofstetter, W; Gerritsma, R

    2013-08-23

    We propose and theoretically investigate a hybrid system composed of a crystal of trapped ions coupled to a cloud of ultracold fermions. The ions form a periodic lattice and induce a band structure in the atoms. This system combines the advantages of high fidelity operations and detection offered by trapped ion systems with ultracold atomic systems. It also features close analogies to natural solid-state systems, as the atomic degrees of freedom couple to phonons of the ion lattice, thereby emulating a solid-state system. Starting from the microscopic many-body Hamiltonian, we derive the low energy Hamiltonian, including the atomic band structure, and give an expression for the atom-phonon coupling. We discuss possible experimental implementations such as a Peierls-like transition into a period-doubled dimerized state.

  15. Atomic-Scale Investigation of Latent Fission Tracks in Fluorapatite: Physical Characteristics and Annealing Behavior.

    NASA Astrophysics Data System (ADS)

    Paul, Tracy Anne

    1993-01-01

    A JEOL JEM-2000FX analytical transmission electron microscope, equipped with a cold stage and anticontamination device, has been used to study the physical characteristics and annealing behavior of artificially induced fission tracks in fluorapatite. Near the atomic level, unetched fission tracks are not continuous, but are comprised of segments of extended damage that are separated by gaps of undamaged microstructure. From dark-field transmission electron microscopy (TEM) images, it appears that the crystalline damage around tracks, although intensive, is not extensive. As such, the defect density may be represented by a Gaussian-type distribution function. The disordered nature of the track core and defect distribution geometry supports the Ion-Explosion Theory that has been proposed for track formation. TEM analysis reveals that track width is crystallographically controlled. Parallel to the c-axis, tracks display widths of 5 to 13 nm and hexagonal faceting on the (0001) plane. Tracks perpendicular to the c-axis display widths of 3 to 9 nm and prismatic faceting on the (1000) plane. The track cross-section facets mimic etch-pit morphologies and provide a relative measure of the crystal's surface free energy. A consequence of differential bond strengths and elastic properties in the fluorapatite structure, track-width anisotropy resolves etching- and annealing-rate anisotropy that has been reported for fission tracks in fluorapatite. TEM observation of the behavior of fission tracks in response to electron beam exposure (i.e., radiolytic annealing), and temperature increase (i.e., thermal annealing), yields a physical and a kinetic description of the annealing process. Annealing commences with bulging at the track's tapered ends, followed by detachment of a single sphere. This process is replicated until a critical track radius is encountered at which the track geometry approaches an ideal right cylinder. A sinusoidal boundary develops at the track

  16. Atomic-level structures and physical properties of magnetic CoSiB metallic glasses

    NASA Astrophysics Data System (ADS)

    Shan, Guangcun; Liang Zhang, Ji; Li, Jiong; Zhang, Shuo; Jiang, Zheng; Huang, Yuying; Shek, Chan-Hung

    2014-02-01

    Two CoSiB metallic glasses of low Co contents, which consist of different clusters, have recently been developed by addition of solute atoms. In this work, the atomic structure and the magnetic properties of the two CoBSi metallic glasses were elucidated by state-of-the-art extended X-ray absorption fine structure spectroscopy (EXAFS) combining with ab initio molecular-dynamics (AIMD) computational techniques. Besides, the origin of these magnetic behaviors was discussed in view of the EXAFS results and atomic structures of the metallic glasses.

  17. Atomic physics of strongly correlated systems. Progress report, 1 August 1980-31 July 1981

    SciTech Connect

    Lin, C.D.

    1981-03-01

    Studies of electron correlations of doubly-excited electrons in hyperspherical coordinates, and differential and total cross sections for charge transfer and ionization in fast ion-atom collisions are reported. (GHT)

  18. A Learning Pathway in High-School Level Quantum Atomic Physics.

    ERIC Educational Resources Information Center

    Petri, Juergen; Niedderer, Hans

    1998-01-01

    Describes one student's learning pathway as a sequence of several metastable conceptions of the atom starting from a planetary model. Displays the final cognitive element as an association of three parallel conceptions. Contains 26 references. (DDR)

  19. Nonlocal thermodynamic equilibrium self-consistent average-atom model for plasma physics.

    PubMed

    Faussurier, G; Blancard, C; Berthier, E

    2001-02-01

    A time-dependent collisional-radiative average-atom model is presented to study statistical properties of highly charged ion plasmas in off-equilibrium conditions. The time evolution of electron populations and the electron covariance matrix is obtained as approximate solutions of a master equation. Atomic structure is described either with a screened-hydrogenic model including l splitting, or by calculating one-electron states in a self-consistent average-atom potential. Collisional and radiative excitation/deexcitation and ionization/recombination rates, as well as autoionization and dielectronic recombination rates, are formulated within the average-configuration framework. Local thermodynamic equilibrium is obtained as a specific steady-state solution. The influence of atomic structure and the role of autoionization and dielectronic recombination processes are studied by calculating steady-state average ionization and ionization variance of hot plasmas with or without radiation field.

  20. A Learning Pathway in High-School Level Quantum Atomic Physics.

    ERIC Educational Resources Information Center

    Petri, Juergen; Niedderer, Hans

    1998-01-01

    Describes one student's learning pathway as a sequence of several metastable conceptions of the atom starting from a planetary model. Displays the final cognitive element as an association of three parallel conceptions. Contains 26 references. (DDR)

  1. FROM THE HISTORY OF PHYSICS: L D Landau in the Soviet Atomic Project: a documentary study

    NASA Astrophysics Data System (ADS)

    Kiselev, G. V.

    2008-09-01

    The article presents information about the participation of Academician L D Landau in the Soviet Atomic Project and is based on a study of archive documents of the First Main Directorate. Their analysis points to L D Landau's important contribution to the development of the theory of heterogeneous nuclear reactors and to the computational justification of the first designs of atomic and hydrogen bombs. Many of the quoted documents have never been published before.

  2. Physical properties of FePt nanocomposite doped with Ag atoms: First-principles study

    NASA Astrophysics Data System (ADS)

    Jia, Yong-Fei; Shu, Xiao-Lin; Xie, Yong; Chen, Zi-Yu

    2014-07-01

    L10 FePt nanocomposite with high magnetocrystalline anisotropy energy has been extensively investigated in the fields of ultra-high density magnetic recording media. However, the order—disorder transition temperature of the nanocomposite is higher than 600 °C, which is a disadvantage for the use of the material due to the sustained growth of FePt grain under the temperature. To address the problem, addition of Ag atoms has been proposed, but the magnetic properties of the doped system are still unclear so far. Here in this paper, we use first-principles method to study the lattice parameters, formation energy, electronic structure, atomic magnetic moment and order—disorder transition temperature of L10 FePt with Ag atom doping. The results show that the formation energy of a Ag atom substituting for a Pt site is 1.309 eV, which is lower than that of substituting for an Fe site 1.346 eV. The formation energy of substituting for the two nearest Pt sites is 2.560 eV lower than that of substituting for the further sites 2.621 eV, which indicates that Ag dopants tend to segregate L10 FePt. The special quasirandom structures (SQSs) for the pure FePt and the FePt doped with two Ag atoms at the stable Pt sites show that the order—disorder transition temperatures are 1377 °C and 600 °C, respectively, suggesting that the transition temperature can be reduced with Ag atom, and therefore the FePt grain growth is suppressed. The saturation magnetizations of the pure FePt and the two Ag atoms doped FePt are 1083 emu/cc and 1062 emu/cc, respectively, indicating that the magnetic property of the doped system is almost unchanged.

  3. -dimensional Symmetry Catalysts for A-Z Gas Loading Fusion

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot

    2011-03-01

    An epitaxial mating of a metal layer to a chemically stable ionic crystal minimizes system energy for cold fusion based on Bloch function symmetry and using gas loading and nm-Pd at a favored interface. To achieve epitaxy second and third metal layers need to have imperfections. One thinks of the stable ionic crystal as a template and the nano-Pd solid as a malleable lattice. The interior volume of the nano-Pd solid has a face-centered cubic structure. ZrO2 was the template ionic crystal used in A-Z gas loading studies at elevated T in (2005). A template crystal using the sapphire crystal equivalent of a double-layer graphene crystal is suggested. Impurity Rh and Ru are suggested as impurity atoms in the nano-metal (as in gem-quality Zircon) and a amall amount of interstitial H in addition to dominant D as involved in diffusion. Ref.

  4. Cu spectroscopy from a z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Dasgupta, Arati; Clark, Robert W.; Ouart, Nicholas D.; Giuliani, John L.

    2014-11-01

    Recent improvements in diagnostic techniques at the Sandia Laboratories Z accelerator have facilitated the production of very detailed x-ray spectral data in the range of 1-20 keV. The high energy density plasma produced in a z-pinch is inherently in non-local thermodynamic equilibrium (NLTE). We therefore employ a NLTE collisional equilibrium model in a 1D radiation-magnetohydrodynamics code to simulate the dynamics of the pinch and to generate synthetic emission spectra. We will discuss the effects on radiation spectra and the yields of using simplifying assumptions in the atomic model and/or the radiation transport. X-ray emission from moderately high atomic number plasmas such as Fe and Cu wire array implosions often include substantial 2p-1s K-α radiation. In a z-pinch plasma, K-shell vacancies can be produced by e-beams, hot electrons at the tail of a Maxwellian and also by photopumping from energetic photons emitted near the pinch axis. In the Z-1975 Cu wire implosion, K-α lines from various ionization stages of Cu as well as from minor constituents including Ni, Fe and Cr are observed. We have calculated K-α production within a full simulation of a Cu implosion, including contributions from energetic electrons and photons. Photo-pumped K-α emission can be distinguished from that produced by e-beams; K-shell vacancies will be produced near the axis for a beam, and near the outer edge of the plasma for energetic photons. Spectroscopic modeling of these K-α lines as well as K- and L-shell emission from valence electrons can provide quantitative diagnostics of plasma parameters. This methodology can also be used to investigate K-α emission from other laboratory experiments such as EBIT and astrophysical plasmas.

  5. Constraints on a long-range spin-independent interaction from precision atomic physics

    SciTech Connect

    Karshenboim, S. G.

    2010-10-01

    Constraints on a spin-independent interaction by the exchange of a neutral light boson are derived from precision data on the electron anomalous magnetic moment and from atomic spectroscopy of hydrogen and deuterium atoms. The mass range from 1 eV/c{sup 2} to 1 MeV/c{sup 2} is studied, and the effective coupling constant {alpha}{sup '} is allowed below the level of 10{sup -11}-10{sup -13} depending on the value of the boson mass. The mass range corresponds to the Yukawa radius from 0.0002 nm to 20 nm, which covers the distances far above and far below the Bohr radius of the hydrogen atom.

  6. Atomic physics with highly charged ions. Progress report, 15 September 1984-14 September 1985

    SciTech Connect

    Richard, P.

    1985-09-01

    Advances are reported in the two areas of primary research: low-energy ion-atom collisions using secondary ion recoil sources, SIRS, and high-energy ion-atom collisions using the tandem Van de Graaff accelerator beams. We have investigated the feasibility of accel-decel with a tandem plus superconducting LINAC with great success, and we have continued to work on the designs of a stand-alone CRYEBIS and a superconducting Nb split-ring resonator LINAC as an appropriate booster for the EN tandem.

  7. How Novel Algorithms and Access to High Performance Computing Platforms are Enabling Scientific Progress in Atomic and Molecular Physics

    NASA Astrophysics Data System (ADS)

    Schneider, Barry I.

    2016-10-01

    Over the past 40 years there has been remarkable progress in the quantitative treatment of complex many-body problems in atomic and molecular physics (AMP). This has happened as a consequence of the development of new and powerful numerical methods, translating these algorithms into practical software and the associated evolution of powerful computing platforms ranging from desktops to high performance computational instruments capable of massively parallel computation. We are taking the opportunity afforded by this CCP2015 to review computational progress in scattering theory and the interaction of strong electromagnetic fields with atomic and molecular systems from the early 1960’s until the present time to show how these advances have revealed a remarkable array of interesting and in many cases unexpected features. The article is by no means complete and certainly reflects the views and experiences of the author.

  8. Atomic physics with highly charged ions. Progress report, FY 1989--91

    SciTech Connect

    Richard, P.

    1991-08-01

    This report discusses: One electron outer shell processes in fast ion-atom collisions; role of electron-electron interaction in two-electron processes; multi-electron processes at low energy; multi-electron processes at high energy; inner shell processes; molecular fragmentation studies; theory; and, JRM laboratory operations.

  9. INSTRUMENTS AND METHODS OF INVESTIGATION: Physical mechanisms underlying the selective removal of atoms

    NASA Astrophysics Data System (ADS)

    Gurovich, Boris A.; Prikhod'ko, Kirill E.

    2009-02-01

    This paper reviews the current understanding of the selective removal of atoms (SRA), a technique that uses ion irradiation to controllably change the chemical composition and properties of polyatomic materials. The main effects involved and the possible mechanisms that govern the process are discussed. It is shown that SRA holds great promise for manufacturing functional nanoelements.

  10. Enhancing Laos Students' Understanding of Nature of Science in Physics Learning about Atom for Peace

    ERIC Educational Resources Information Center

    Sengdala, Phoxay; Yuenyong, Chokchai

    2014-01-01

    This paper aimed to study of Grade 12 students' understanding of nature of science in learning about atom for peace through science technology and society (STS) approach. Participants were 51 Grade 12 who study in Thongphong high school Vientiane Capital City Lao PDR, 1st semester of 2012 academic year. This research regarded interpretive…

  11. The physics of coal liquid slurry atomization. Final report to Department of Energy - PETC

    SciTech Connect

    Chigier, N.; Mansour, A.

    1995-10-01

    The stability of turbulent columns of liquid injected into a quiescent environment was studied. Laser Doppler Anemometry measurements of the flow patterns and turbulence characteristics in free liquid jets were made. Turbulence decay along Newtonian jets was investigated along with the effects of turbulence on the resulting droplet size distributions after breakup. The rate of decay of turbulence properties along the jet were investigated. Disintegration of liquid jets injected into a high-velocity gas stream has also been studied. Newtonian and non-Newtonian liquids were studied with particular emphasis on the non-Newtonian rheological characteristics. Determination was made of the extent that the addition of high molecular weight polymer to liquids change the breakup process. Shear thinning, extension thinning and extension thickening fluids were investigated. Shear viscosities were measured over five decades of shear rates. The contraction flow technique was also used for measurement of the extensional viscosity of non-Newtonian liquids. The die-swell technique was also used to determine the first normal stress difference. The near field produced by a co-axial airblast atomizer was investigated using the phase Doppler particle analyzer. Whether or not the classical wave mechanism and empirical models reported for airblast atomization of low viscosity liquid are applicable to airblast atomization of viscous non-Newtonian liquids was determined. The theoretical basis of several models which give the best fit to the experimental data for airblast atomization of non-Newtonian liquids was also discussed. The accuracy of the wave mechanism-based models in predicting droplets sizes after breakup of viscous non-Newtonian liquids using an airblast atomizer has also been demonstrated.

  12. Atomic polarizabilities

    SciTech Connect

    Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  13. Atomic physics measurements using an ECR ion source located on a 350-kV high-voltage platform

    SciTech Connect

    Dunford, R.W.; Berry, H.G.; Liu, C.J.; Hass, M.; Pardo, R.C.; Raphaelian, M.L.A.; Zabransky, B.J.

    1988-01-01

    We report on a new atomic physics facility at the Argonne PII ECR ion source which was built for the Uranium Upgrade of the ATLAS heavy-ion accelerator. An important feature of our ECR ion source is that it is on a high-voltage platform which provides beam energies of up to 350q keV, where q is the charge of the ion. We discuss the experimental program in progress at this ion source which includes measurements of state-selective electron capture cross sections, photon and electron spectroscopy, studies of quasi-molecular collisions, and polarization studies using an optically pumped Na target. 9 refs., 6 figs.

  14. Divisible Atoms or None at All? Facing the European Contributions to Developments of Chemistry and Physics in China.

    PubMed

    Južnič, Stanislav

    2016-12-01

    atoms is discussed as possible new paradigm which could rename the destructible divisible entities of future physics, and with more difficulties also of chemistry. The word atom meaning indivisible not compound entity is basically in contradiction with the characteristics of item it is supposed to describe. The suffix "a" provides a negation in Ancient Greek language. The suffix should be omitted to use tom (τομος) to manage the actual situation of a-toms (=Toms) as compound of elementary particles. In late 19th century after the European Spring of Nations actually two basically different concepts of atoms of chemists and physicists accomplished a kind of symbioses. The suggestion is put forward that while indivisible atoms soon became contradictions in physics, they still retain some value in chemistry which should be taken into account in the attempt to hange the name of atom. The research of human genome as the atom of genetics is similar in broader sense, while there is no basic problem with the nomenclature of genome. The genome manipulations are far less obstructed with Chinese traditions compared to Christian beliefs.

  15. Precision Physics of Simple Atoms and Constraints on a Light Boson with Ultraweak Coupling

    SciTech Connect

    Karshenboim, S. G.

    2010-06-04

    Constraint on spin-dependent and spin-independent Yukawa potential at atomic scale is developed. That covers constraints on a coupling constant of an additional photon {gamma}* and a pseudovector boson. The mass range considered is from 1 eV/c{sup 2} to 1 MeV/c{sup 2}. The strongest constraint on a coupling constant {alpha}{sup '} is at the level of a few parts in 10{sup 13} (for {gamma}*) and below one part in 10{sup 16} (for a pseudovector) corresponding to mass below 1 keV/c{sup 2}. The constraints are derived from low-energy tests of quantum electrodynamics and are based on spectroscopic data on light hydrogenlike atoms and experiments with magnetic moments of leptons and light nuclei.

  16. The Physics of Miniature Atomic Clocks: 0-0 Versus "End" Transitions

    NASA Astrophysics Data System (ADS)

    Post, Amber; Jau, Yuan-Yu; Kuzma, Nicholas; Happer, William

    2003-05-01

    The majority of traditional atomic-clock designs are based on the 0-0 hyperfine transition of a Cs 133 atom. We are currently investigating the advantages of operating a miniature optical atomic clock using the "end" transitions, e.g. connecting states |f=1, mf =+/-1> and |f=2, mf=+/-2> in 87Rb. In our paper we present extensive new measurements of relevant relaxation rates, such as those due to spin-exchange collisions, buffer-gas pressure shifts, Carver Rates and others, which ultimately determine the choices of an operating regime for the miniature optical atomic clock. The relationship between these rates is non-trivial: for example, using higher laser power will increase polarization and reduce the spin-exchange rate [1], but it can simultaneously increase the linewidth due to the optical pumping rate. The dependence of these and other relaxation rates on the cell size, temperature, pressure, a choice of buffer gas, and other parameters will be reported. Based on these measured rates, our modeling can be used to predict the transition linewidths, signal-to-noise ratios and thus the stability of the clock in different operating regimes. The trade-off between the stability of the clock and the desired small cell size and low power consumption needs to be carefully considered in order to optimize our design. In our experiments we used optical, microwave, and radio-frequency excitation to study hyperfine and Zeeman resonance lines in heated glass cells containing pure-isotope alkali-metal vapor and buffer gasses (N2, Ar, He, etc.) at low (0 - 10 G) magnetic fields. Simultaneous use of light, microwave and radio-frequency fields allowed us to calibrate surrounding magnetic fields by observing the corresponding shifts of the resonance, thus leading us to a quantitative understanding of our system. [1] S. Appelt, A. B. Baranga, A. R. Young, W. Happer, Phys. Rev. A 59, 2078 (1999).

  17. An electrostatic storage ring for atomic and molecular physics, at KACST - a status report

    NASA Astrophysics Data System (ADS)

    El Ghazaly, Mohamed O. A.

    2015-01-01

    An electrostatic storage ring has been designed following the pioneering storage ring ELISA [1], and it is currently being built as a new core laboratory for atomic and molecular collisions at the King Abdulaziz City for Science and Technology (KACST), in Riyadh, Saudi Arabia. In this paper, the design of the electrostatic storage ring together with an outline on the status of the construction are given.

  18. The Scales of Time, Length, Mass, Energy, and Other Fundamental Physical Quantities in the Atomic World and the Use of Atomic Units in Quantum Mechanical Calculations

    ERIC Educational Resources Information Center

    Teo, Boon K.; Li, Wai-Kee

    2011-01-01

    This article is divided into two parts. In the first part, the atomic unit (au) system is introduced and the scales of time, space (length), and speed, as well as those of mass and energy, in the atomic world are discussed. In the second part, the utility of atomic units in quantum mechanical and spectroscopic calculations is illustrated with…

  19. The Scales of Time, Length, Mass, Energy, and Other Fundamental Physical Quantities in the Atomic World and the Use of Atomic Units in Quantum Mechanical Calculations

    ERIC Educational Resources Information Center

    Teo, Boon K.; Li, Wai-Kee

    2011-01-01

    This article is divided into two parts. In the first part, the atomic unit (au) system is introduced and the scales of time, space (length), and speed, as well as those of mass and energy, in the atomic world are discussed. In the second part, the utility of atomic units in quantum mechanical and spectroscopic calculations is illustrated with…

  20. [Physical Properties of Squamous Cell Carcinoma Cells using Atomic Force Microscopy].

    PubMed

    Kristin, J; Steeger, S; Schreyer, T; Hansen, S; Glaas, M F; Stenin, I; Getzlaff, M; Schipper, J

    2016-04-01

    Malignant and benign cells differ according to their elasticity. An atomic force microscope is a useful tool for measuring these mechanical cell properties. If cells of different dignity show different resonance behavior, due to their different elasticity, a selective ablation of specific tissue types by ultrasound would be possible. The goal is a highly selective ablation of tumor tissue without damaging healthy tissue. We performed elasticity measurements of tumor cells (UD-01 cell line) with an atomic force microscope. In a further step, an ultrasound applicator has been positioned and the morphological changes of the cells during the treatment were documented. Different elasticities on the squamous cells were measured, depending on the location. Below a defined maximum amplitude the morphological cell changes were caused solely by ultrasonic excitation. The atomic force microscope is suitable for the determination of the individual cell elasticity. The data collected could be the basis for treatment modalities that lead to a very selective damage for malignant cells. © Georg Thieme Verlag KG Stuttgart · New York.

  1. The problems of solar-terrestrial coupling and new processes introduced to the physics of the ionosphere from the physics of atomic collisions

    NASA Astrophysics Data System (ADS)

    Avakyan, Sergei

    2010-05-01

    Further progress in research of solar-terrestrial coupling requires better understanding of solar variability influence on the ionosphere. The most powerful manifestations of solar variability are solar flares and geomagnetic storms. During a flare EUV/X-ray irradiations are completely absorbed in the ionosphere producing SID. During geomagnetic storms precipitations of electrons with energy of several keV (and to a lesser extent protons precipitations) from radiation belts and geomagnetosphere produce additional ionization and low latitude auroras. Considering the physics of ionosphere during the last several decades we have been taking into account three novel processes well known in the physics of atomic collisions. These are Auger effect [S. V. Avakyan, The consideration of Auger processes in the upper atmosphere of Earth. In Abstracts of paper presented at the Tenth scien. and techn. Conf. of young specialists of S.I. Vavilov State Optical Institute, 1974, 29-31.], multiple photoionization of upper, valence shell [S.V. Avakyan, The source of O++ ions in the upper atmosphere, 1979, Cosmic Res, 17, 942 - 943] and Rydberg excitation of all the components of upper atmosphere [S.V. Avakyan, The new factor in the physics of solar - terrestrial relations - Rydberg atomic and molecules states. Conf. on Physics of solar-terrestrial relationships, 1994, Almaty, 3 - 5]. In the present paper the results of bringing these new processes in the ionospheric physics are discussed and also its possible role in the physics of solar-terrestrial coupling is considered. Involving these processes to the model estimations allowed us for the first time to come to the following important conclusions: - Auger electrons play the determinant role at the formation of energy spectrum of photoelectrons and secondary auroral electrons at the range above 150 eV; - double photoionization of the outer shell of the oxygen atom (by a single photon) plays a dominant role in the formation of

  2. The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards.

    PubMed

    Riley, W R

    1992-01-01

    The physical mechanisms behind environmental sensitivity are considered, and they are related to the performances of rubidium frequency standards (RFSs). Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of DC magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environmental factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget, with large unit-to-unit variations. Today's RFSs span a wide performance range from small, inexpensive units with pp10(10) error budgets to larger, higher-performance versions offering pp10(14) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case is explained, and some insight into how to make improvements is offered.

  3. Workshop on Coupled-Cluster Theory at the Interface of Atomic Physics and Quantum Chemistry

    DTIC Science & Technology

    1991-03-05

    potentials, electron affinities, and Auger spectroscopy, Fock space multi-reference methods (as discussed at the workshop by Mukherjee, Kaldor , Rittby...Bishop K. Jankowski Zuwei Liu University of Manchester Nicholas Capernicus University University of Virginia Dept. of Mathematics Institute of Physics...Kingston, NY 12401 Bhanu Pratap Das Uzi Kaldor Peter Mohr Utah State University Tel Aviv University National Institute of Standards & Physics Dept

  4. Spectral and Atomic Physics Analysis of Xenon L-Shell Emission From High Energy Laser Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Thorn, Daniel; Kemp, G. E.; Widmann, K.; Benjamin, R. D.; May, M. J.; Colvin, J. D.; Barrios, M. A.; Fournier, K. B.; Liedahl, D.; Moore, A. S.; Blue, B. E.

    2016-10-01

    The spectrum of the L-shell (n =2) radiation in mid to high-Z ions is useful for probing plasma conditions in the multi-keV temperature range. Xenon in particular with its L-shell radiation centered around 4.5 keV is copiously produced from plasmas with electron temperatures in the 5-10 keV range. We report on a series of time-resolved L-shell Xe spectra measured with the NIF X-ray Spectrometer (NXS) in high-energy long-pulse (>10 ns) laser produced plasmas at the National Ignition Facility. The resolving power of the NXS is sufficiently high (E/ ∂E >100) in the 4-5 keV spectral band that the emission from different charge states is observed. An analysis of the time resolved L-shell spectrum of Xe is presented along with spectral modeling by detailed radiation transport and atomic physics from the SCRAM code and comparison with predictions from HYDRA a radiation-hydrodynamics code with inline atomic-physics from CRETIN. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  5. A note on black-hole physics, cosmic censorship, and the charge-mass relation of atomic nuclei

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2016-02-01

    Arguing from the cosmic censorship principle, one of the fundamental cornerstones of black-hole physics, we have recently suggested the existence of a universal upper bound relating the maximal electric charge of a weakly self-gravitating system to its total mass: Z(A)≤slant {Z}*(A)\\equiv {α }-1/3{A}2/3, where Z is the number of protons in the system, A is the total baryon (mass) number, and α ={e}2/{{\\hslash }}c is the dimensionless fine-structure constant. In order to test the validity of this suggested bound, we here explore the Z(A) functional relation of atomic nuclei as deduced from the Weizsäcker semi-empirical mass formula. It is shown that all atomic nuclei, including the meta-stable maximally charged ones, conform to the suggested charge-mass upper bound. Our results support the validity of the cosmic censorship conjecture in black-hole physics.

  6. The application of atomic physics within impurity diagnostics for fusion plasmas

    SciTech Connect

    Loch, S. D.; Ballance, C. P.; Pindzola, M. S.; Griffin, D. C.

    2013-04-19

    With the focus of ITER on the transport and emission properties of tungsten, generating atomic data for complex species has received much interest. Focusing on impurity influx diagnostics, we discuss recent work on heavy species. Perturbative approaches do not work well for near neutral systems so non-perturbative data are required, presenting a particular challenge for these influx diagnostics. Recent results on Mo{sup +} are given as an illustration of how the diagnostic applications can guide the theoretical calculations for such systems.

  7. Davisson-Germer Prize Talk: Many-Body Physics with Atomic Fermions

    NASA Astrophysics Data System (ADS)

    Hulet, Randall

    2016-05-01

    Ultracold atomic gases confined to optical lattices have proven to be highly versatile and tunable systems for realizing novel quantum states of matter. We are using Fermi gases of 6 Li atoms in our laboratory to explore several goals related to the strong correlations that arise in these systems. We have realized the Hubbard model, which has long been suspected of containing the essential ingredients of high temperature superconductivity. We measured the compressibility of the Mott insulating phase that occurs near half filling (1 atom/site), thus demonstrating the excitation gap of the Mott insulator. Progress in this field, however, has been hampered by an inability to cool to low enough temperatures to achieve the most ambitious goals. To address this problem, we have developed the compensated optical lattice method to enable evaporative cooling in the lattice. With this method, we have cooled the Mott insulator sufficiently far to observe short-range antiferromagnetic correlations using Bragg scattering of light. We are currently exploring new methods for entropy storage and redistribution to achieve even lower entropy in the antiferromagnetic phase. Motivated by the enhancement of quantum correlations in low dimensions, we are also exploring Fermi gases in quasi-one-dimension (1D). A deep 2D optical lattice produces an array of 1D tubes which can be weakly coupled by reducing the lattice depth, thus increasing the lattice hopping t between them. We observe a crossover from 1D-like to 3D-like behavior in the phase separation of a spin-imbalanced Fermi gas with increasing t. While this crossover occurs at a value of t that depends on interaction, we find that the crossover location is universally dependent upon the scaled hopping t /ɛb , where ɛb is the pair binding energy. Finally, I will also report progress on measuring the speed of sound of the charge and spin modes in a 1D Fermi gas. Work supported by an ARO MURI, NSF, and the Robert A Welch Foundation.

  8. Physics and the New Games -- or Pretend You're an Atom.

    ERIC Educational Resources Information Center

    Edge, Ronald D.

    1982-01-01

    Describes several games in which physics principles are demonstrated using students. These include Pirates Treasure Game (vectors), Three-Meter Dash (kinematics), Knee-Bend Game (energy and power), Wave Game, Reaction Kinematics, Statics-People Pyramids, and games demonstrating nuclear reactions, collisions, electrons in a wire, close packing, and…

  9. Physics and the New Games -- or Pretend You're an Atom.

    ERIC Educational Resources Information Center

    Edge, Ronald D.

    1982-01-01

    Describes several games in which physics principles are demonstrated using students. These include Pirates Treasure Game (vectors), Three-Meter Dash (kinematics), Knee-Bend Game (energy and power), Wave Game, Reaction Kinematics, Statics-People Pyramids, and games demonstrating nuclear reactions, collisions, electrons in a wire, close packing, and…

  10. Point defect dynamics in MOSFETs -- From atomic-scale physics to engineering models

    NASA Astrophysics Data System (ADS)

    Pantelides, Sokrates T.

    2003-03-01

    Dopant impurities are the key ingredient that makes semiconductors so useful in microelectronics. Other point defects, e.g., vacancies and self-interstitial, play major roles in mediating diffusion, which can be both good and bad. Hydrogen is another element that is very useful in passivating point defects at the Si-SiO2 interface of metal-oxide-semiconductor field-effect transistors (MOSFETs), but it also lurks dormant in all kinds of places. Oxygen vacancies also abound dormant and benign in the SiO2 gate layer, but both hydrogen and oxygen vacancies reveal sinister personas when radiation strikes (as in space electronics). This talk will give a brief account of how, over the last few decades, atomic-scale quantum mechanical calculations have impacted the process of constructing engineering models that are used in technology development and then focus on recent results on point defect dynamics in MOSFETs, some of which have been fed into engineering models.

  11. Atomic physics modeling of transmission spectra of Sc-doped aerogel foams to support OMEGA experiments

    SciTech Connect

    Johns, H. M. Lanier, N. E.; Kline, J. L.; Fontes, C. J.; Perry, T. S.; Fryer, C. L.; Sherrill, M. E.; Brown, C. R. D.; Morton, J. W.; Hager, J. D.

    2016-11-15

    We present synthetic transmission spectra generated with PrismSPECT utilizing both the ATBASE model and the Los Alamos opacity library (OPLIB) to evaluate whether an alternative choice in atomic data will impact modeling of experimental data from radiation transport experiments using Sc-doped aerogel foams (ScSi{sub 6}O{sub 12} at 75 mg/cm{sup 3} density). We have determined that in the 50-200 eV T{sub e} range there is a significant difference in the 1s-3p spectra, especially below 100 eV, and for T{sub e} = 200 eV above 5000 eV in photon energy. Examining synthetic spectra generated using OPLIB with 300 resolving power reveals spectral sensitivity to T{sub e} changes of ∼3 eV.

  12. Atomic physics modeling of transmission spectra of Sc-doped aerogel foams to support OMEGA experiments

    NASA Astrophysics Data System (ADS)

    Johns, H. M.; Lanier, N. E.; Kline, J. L.; Fontes, C. J.; Perry, T. S.; Fryer, C. L.; Brown, C. R. D.; Morton, J. W.; Hager, J. D.; Sherrill, M. E.

    2016-11-01

    We present synthetic transmission spectra generated with PrismSPECT utilizing both the ATBASE model and the Los Alamos opacity library (OPLIB) to evaluate whether an alternative choice in atomic data will impact modeling of experimental data from radiation transport experiments using Sc-doped aerogel foams (ScSi6O12 at 75 mg/cm3 density). We have determined that in the 50-200 eV Te range there is a significant difference in the 1s-3p spectra, especially below 100 eV, and for Te = 200 eV above 5000 eV in photon energy. Examining synthetic spectra generated using OPLIB with 300 resolving power reveals spectral sensitivity to Te changes of ˜3 eV.

  13. The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards

    NASA Technical Reports Server (NTRS)

    Riley, William J.

    1990-01-01

    Environmental sensitivity is often the most significant limitation to the practical stability of rubidium frequency standards (RFS). For example, temperature sensitivity can cause a rapid frequency change of several parts in 10(exp 10) for a tactical RFS that has an aging of only 1 times 10(exp -11)/month. Other important environmental factors are barometric pressure, vibration, magnetic field, and nuclear radiation. The physical mechanisms that lie behind these environmental sensitivities are considered. These physical mechanisms are related to the performance of actual rubidium frequency standards. For the user of these devices, a better knowledge of the causes for Rb clock instability will aid in their testing and proper application. For the time frequency specialist, a review of these factors may prove useful toward improving RFS design. Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of dc magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environment factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget with large unit-to-unit variations. Today's rubidium frequency standards span a wide performance range from small, inexpensive units with pp 10(exp 10) error budgets to larger, higher performance versions offering pp 10(exp 10) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case and how to make improvements are discussed.

  14. The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards

    NASA Technical Reports Server (NTRS)

    Riley, William J.

    1990-01-01

    Environmental sensitivity is often the most significant limitation to the practical stability of rubidium frequency standards (RFS). For example, temperature sensitivity can cause a rapid frequency change of several parts in 10(exp 10) for a tactical RFS that has an aging of only 1 times 10(exp -11)/month. Other important environmental factors are barometric pressure, vibration, magnetic field, and nuclear radiation. The physical mechanisms that lie behind these environmental sensitivities are considered. These physical mechanisms are related to the performance of actual rubidium frequency standards. For the user of these devices, a better knowledge of the causes for Rb clock instability will aid in their testing and proper application. For the time frequency specialist, a review of these factors may prove useful toward improving RFS design. Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of dc magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environment factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget with large unit-to-unit variations. Today's rubidium frequency standards span a wide performance range from small, inexpensive units with pp 10(exp 10) error budgets to larger, higher performance versions offering pp 10(exp 10) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case and how to make improvements are discussed.

  15. Physical adsorption: rare gas atoms on solid surfaces. Progress report, June 1, 1980-May 31, 1981

    SciTech Connect

    Cole, M.W.

    1981-02-01

    This project has entailed investigation of three areas during the current term: physical adsorption, photostimulated field emission (PSE), and phonon reflection at interfaces. The principal effort has been directed toward understanding interactions associated with physical adsorption and the associated properties of a film. The specific topics pursued include the detailed form of the long range interaction, the configuration space wave function, and the interaction between adatoms. Experimental confirmation of the last two come from neutron scattering and thermodynamic measurements, respectively. The research in PSE has yielded results which improve upon previous calculations. There is, however, a remaining disagreement with experiment; suggestions for the origin are discussed. The phonon reflection work is directed toward understanding the role of surface roughness, an important factor in increasing the energy transmission across interfaces. A formalism has been developed which will be evaluated in the future.

  16. Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles, 2nd Edition

    NASA Astrophysics Data System (ADS)

    Eisberg, Robert; Resnick, Robert

    1985-01-01

    A revision of a successful junior/senior level text, this introduction to elementary quantum mechanics clearly explains the properties of the most important quantum systems. Emphasizes the applications of theory, and contains new material on particle physics, electron-positron annihilation in solids and the Mossbauer effect. Includes new appendices on such topics as crystallography, Fourier Integral Description of a Wave Group, and Time-Independent Perturbation Theory.

  17. HISTRAP: Proposal for a Heavy Ion Storage Ring for Atomic Physics

    SciTech Connect

    Not Available

    1988-11-01

    This paper presents an overview of the physics capabilities of HISTRAP together with a brief description of the facility and a sampling of the beams which will be available for experimentation, and surveys some of the lines of investigation in the physics of multicharged ions, molecular ion spectroscopy, condensed beams, and nuclear physics that will become possible with the advent of HISTRAP. Details of the accelerator design are discussed, including computer studies of beam tracking in the HISTRAP lattice, a discussion of the HHIRF tandem and ECR/RFQ injectors, and a description of the electron beam cooling system. In the past three years, HISTRAP has received substantial support from Oak Ridge National Laboratory management and staff. The project has used discretionary funds to develop hardware prototypes and carry out design studies. Construction has been completed on a vacuum test stand which models 1/16 of the storage ring and has attained a pressure of 4 x 10/sup -12/ Torr; a prototype rf cavity capable of accelerating beams up to 90 MeV/nucleon and decelerating to 20 keV/nucleon; and a prototype dipole magnet, one of the eight required for the HISTRAP lattice. This paper also contains a summary of the work on electron cooling carried out by one of our staff members at CERN. Building structures and services are described. Details of cost and schedule are also discussed. 77 refs.

  18. Atomic Force Microscopy of Physical and Chemical Processes at the Solid-Liquid Interface

    NASA Astrophysics Data System (ADS)

    Manne, Srinivas

    This thesis describes research using atomic force microscopy (AFM) to study dynamics of solid surfaces in contact with liquids. Specifically, three applications are described: electrochemistry (Chapters 1-3), crystal growth (Chapters 4 and 5), and biomineralization (Chapter 6). Chapter 1 shows the feasibility of using AFM to image metal atoms in liquid, which sets the stage for high -resolution electrochemistry. Chapter 2 describes methods to convert the standard AFM liquid cell into an electrochemical cell and shows images of a gold electrode during oxidation/reduction cycling. Chapter 3 follows an electroplating cycle, wherein copper is deposited from electrolyte onto a gold electrode and then stripped off. The surface lattice is shown to change from that of bulk gold to bulk copper during plating, and back to bulk gold after stripping. Moreover, the first monolayer of copper--which deposits at an "underpotential", before the bulk deposition--is shown to have a lattice which differs from the bulk and is electrolyte dependent. Like electrochemistry, the study of crystal growth is also perfectly suited to a surface technique such as AFM. AFM makes it possible to image "elemental steps" (i.e., steps one unit cell thick) on a single crystal and quantify their motion during growth and dissolution. This is illustrated for the inorganic crystal calcite (Chapter 4) and the more fragile organic crystal L-leucine (Chapter 5). In both cases it is shown that step speed is independent of spacing between steps, indicating that motion occurs by direct interaction of the step-site molecules with the solvent. Chapter 5 also describes techniques for growing and imaging organic crystals. Living organisms also use crystal growth, modified by inorganic and organic additives, to grow mineralized structures such as bones, teeth and seashells. In Chapter 6, AFM reveals the three-dimensional structure of the nacreous or pearly layer of mollusc shells by slowly etching away successive

  19. On the physical and chemical details of alumina atomic layer deposition: A combined experimental and numerical approach

    SciTech Connect

    Pan, Dongqing; Ma, Lulu; Xie, Yuanyuan; Yuan, Chris; Jen, Tien Chien

    2015-03-15

    Alumina thin film is typically studied as a model atomic layer deposition (ALD) process due to its high dielectric constant, high thermal stability, and good adhesion on various wafer surfaces. Despite extensive applications of alumina ALD in microelectronics industries, details on the physical and chemical processes are not yet well understood. ALD experiments are not able to shed adequate light on the detailed information regarding the transient ALD process. Most of current numerical approaches lack detailed surface reaction mechanisms, and their results are not well correlated with experimental observations. In this paper, the authors present a combined experimental and numerical study on the details of flow and surface reactions in alumina ALD using trimethylaluminum and water as precursors. Results obtained from experiments and simulations are compared and correlated. By experiments, growth rate on five samples under different deposition conditions is characterized. The deposition rate from numerical simulation agrees well with the experimental results. Details of precursor distributions in a full cycle of ALD are studied numerically to bridge between experimental observations and simulations. The 3D transient numerical model adopts surface reaction kinetics and mechanisms based on atomic-level studies to investigate the surface deposition process. Surface deposition is shown as a strictly self-limited process in our numerical studies. ALD is a complex strong-coupled fluid, thermal and chemical process, which is not only heavily dependent on the chemical kinetics and surface conditions but also on the flow and material distributions.

  20. Threshold Laws for Two-Electron Ejection Processes: A Still Controversial Problem in Atomic Physics

    NASA Technical Reports Server (NTRS)

    Temkin, Aaron

    2003-01-01

    This talk deals with collision processes of the following kind: (a) an ionizing collision of an electron with a neutral atom, (b) a photon incident of a negative ion resulting in two-electron ejection. In both cases the final state is a positive ion and two outgoing electrons, and in principle both processes should be governed by the same form of threshold law. It is generally conceded that this is one of the most difficult basic problems in nonrelativistic quantum mechanics. The standard treatment (due to Wannier) will be briefly reviewed in terms of the derivation of his well- known threshold law for the yield (Q) of positive ions vs. the excess energy (E): Q(sub w) varies as E(exp 1.127...). The derivation is a brilliant analysis based on Newton's equations, leading to the dominance of events in which the two electrons emerge on opposite sides of the residual ion with similar energies. In contrast, I will argue on the basis of quantum mechanical ideas that in the threshold limit the more likely outcome are events in which the electrons emerge with decidedly different energies, leading to a formally different (Coulomb-dipole) threshold law Q(sub CD) varies as E(1 + C sin(alpha ln(E)+mu)]/[ln(E)](exp 2). Additional aspects of that approach will be discussed . Some: experimental results will be presented, and more incisive predictions involving polarized projectiles and targets will be given.

  1. Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena.

    PubMed

    Cottet, Audrey; Dartiailh, Matthieu C; Desjardins, Matthieu M; Cubaynes, Tino; Contamin, Lauriane C; Delbecq, Matthieu; Viennot, Jérémie J; Bruhat, Laure E; Douçot, Benoit; Kontos, Takis

    2017-09-19

    Circuit QED techniques have been instrumental in manipulating and probing with exquisite sensitivity the quantum state of superconducting quantum bits coupled to microwave cavities. Recently, it has become possible to fabricate new devices in which the superconducting quantum bits are replaced by hybrid mesoscopic circuits combining nanoconductors and metallic reservoirs. This mesoscopic QED provides a new experimental playground to study the light-matter interaction in electronic circuits. Here, we present the experimental state of the art of mesoscopic QED and its theoretical description. A first class of experiments focuses on the artificial atom limit, where some quasiparticles are trapped in nanocircuit bound states. In this limit, the circuit QED techniques can be used to manipulate and probe electronic degrees of freedom such as confined charges, spins, or Andreev pairs. A second class of experiments uses cavity photons to reveal the dynamics of electron tunneling between a nanoconductor and fermionic reservoirs. For instance, the Kondo effect, the charge relaxation caused by grounded metallic contacts, and the photo-emission caused by voltage-biased reservoirs have been studied. The tunnel coupling between nanoconductors and fermionic reservoirs also enable one to obtain split Cooper pairs, or Majorana bound states. Cavity photons represent a qualitatively new tool to study these exotic condensed matter states.

  2. Threshold Laws for Two-Electron Ejection Processes: A Still Controversial Problem in Atomic Physics

    NASA Technical Reports Server (NTRS)

    Temkin, Aaron

    2003-01-01

    This talk deals with collision processes of the following kind: (a) an ionizing collision of an electron with a neutral atom, (b) a photon incident of a negative ion resulting in two-electron ejection. In both cases the final state is a positive ion and two outgoing electrons, and in principle both processes should be governed by the same form of threshold law. It is generally conceded that this is one of the most difficult basic problems in nonrelativistic quantum mechanics. The standard treatment (due to Wannier) will be briefly reviewed in terms of the derivation of his well- known threshold law for the yield (Q) of positive ions vs. the excess energy (E): Q(sub w) varies as E(exp 1.127...). The derivation is a brilliant analysis based on Newton's equations, leading to the dominance of events in which the two electrons emerge on opposite sides of the residual ion with similar energies. In contrast, I will argue on the basis of quantum mechanical ideas that in the threshold limit the more likely outcome are events in which the electrons emerge with decidedly different energies, leading to a formally different (Coulomb-dipole) threshold law Q(sub CD) varies as E(1 + C sin(alpha ln(E)+mu)]/[ln(E)](exp 2). Additional aspects of that approach will be discussed . Some: experimental results will be presented, and more incisive predictions involving polarized projectiles and targets will be given.

  3. Numerical Aspects of Atomic Physics: Helium Basis Sets and Matrix Diagonalization

    NASA Astrophysics Data System (ADS)

    Jentschura, Ulrich; Noble, Jonathan

    2014-03-01

    We present a matrix diagonalization algorithm for complex symmetric matrices, which can be used in order to determine the resonance energies of auto-ionizing states of comparatively simple quantum many-body systems such as helium. The algorithm is based in multi-precision arithmetic and proceeds via a tridiagonalization of the complex symmetric (not necessarily Hermitian) input matrix using generalized Householder transformations. Example calculations involving so-called PT-symmetric quantum systems lead to reference values which pertain to the imaginary cubic perturbation (the imaginary cubic anharmonic oscillator). We then proceed to novel basis sets for the helium atom and present results for Bethe logarithms in hydrogen and helium, obtained using the enhanced numerical techniques. Some intricacies of ``canned'' algorithms such as those used in LAPACK will be discussed. Our algorithm, for complex symmetric matrices such as those describing cubic resonances after complex scaling, is faster than LAPACK's built-in routines, for specific classes of input matrices. It also offer flexibility in terms of the calculation of the so-called implicit shift, which is used in order to ``pivot'' the system toward the convergence to diagonal form. We conclude with a wider overview.

  4. The 1953 Cosmic Ray Conference at Bagnères de Bigorre: the Birth of Sub Atomic Physics

    NASA Astrophysics Data System (ADS)

    Cronin, J. W.

    2011-04-01

    The cosmic ray conference at Bagnères de Bigorre in July, 1953 organized by Patrick Blackett and Louis Leprince-Ringuet was a seminal one. It marked the beginning of sub atomic physics and its shift from cosmic ray research to research at the new high energy accelerators. The knowledge of the heavy unstable particles found in the cosmic rays was essentially correct in fact and interpretation and defined the experiments that needed to be carried out with the new accelerators. A large fraction of the physicists who had been using cosmic rays for their research moved to the accelerators. This conference can be placed in importance in the same category as two other famous conferences, the Solvay congress of 1927 and the Shelter Island Conference of 1948.

  5. A new data acquisition system for Schottky signals in atomic physics experiments at GSI's and FAIR's storage rings

    NASA Astrophysics Data System (ADS)

    Trageser, C.; Brandau, C.; Kozhuharov, C.; Litvinov, Yu A.; Müller, A.; Nolden, F.; Sanjari, S.; Stöhlker, T.

    2015-11-01

    A new continuous and broadband data acquisition system for measurements of Schottky-signals of ions revolving in a storage ring has been implemented. This set-up is capable of recording the radio frequency (RF) signal of the ions that circulate in the storage ring with a sustained acquisition rate of more than 3.5× {10}7 IQ-samples per second. This allows several harmonics of the full momentum acceptance of a storage ring to be measured at the same time. The RF signal analyzer modules are complemented by further electronic modules such as counters, precision clocks and synchronization modules that facilitate a seamless integration with main experimental data acquisitions for atomic and nuclear physics. In this contribution, the setup and first results from a test run at the experimental storage ring at GSI, Darmstadt, Germany, are presented.

  6. First atomic physics experiments with cooled stored ion beams at the Heidelberg heavy-ion ring TSR

    SciTech Connect

    Wolf, A.; Balykin, V.; Baumann, W.; Berger, J.; Bisoffi, G.; Blatt, P.; Blum, M.; Faulstich, A.; Friedrich, A.; Gerhard, M.; Geyer, C.; Grieser, M.; Grieser, R.; Habs, D.; Heyng, H.W.; Hochadel, B.; Holzer, B.; Huber, G.; Jaeschke, E.; Jung, M.; Karafillidis, A.; Kilgus, G.; Klein, R.; Kraemer, D.; Krause, P.; Krieg, M.; Kuehl, T.; Matl, K.; Mueller, A.; Music, M.; Neumann, R.; Neureither, G.; Ott, W.; Petrich, W.; Povh, B.; Repnow, R.; Schroeder, S.; Schuch, R.; Schwalm, D.; Sigray, P.; Steck, M.; Stokstad, R.; Szmola, E.; Wagner, M.; Wanner, B.; Welti, K.; Zwickler, S. Max-Planck-Institut fuer Kernphysik, Heidelberg Manne Siegbahn Institute , Stockholm Institut fuer Kernphysik, Universitaet Giessen, Institut fuer Physik, Universitaet Mainz Gesellschaft fuer Schwerionenforschung , Darmstadt (Fed

    1990-06-01

    An overview of atomic physics experiments at the heavy ion Test Storage Ring (TSR) is given. Highly charged ions up to fully stripped silicon have been stored at energies between 4 and 12 MeV/u. The enhancement of the beam intensity by stacking, the beam lifetime, and electron cooling of these ion beams are discussed. Radiative and state-selective dielectronic recombination rates of hydrogen-like oxygen ions with free electrons from the electron cooler were measured. Beam noise spectra are being investigated with regard to collective effects caused by the Coulomb interaction in the cold ion beams. Resonance fluorescence from stored single-charged ions was observed using tunable narrow-band lasers. First indications of laser cooling in a storage ring were seen.

  7. Atomic Radiations in the Decay of Medical Radioisotopes: A Physics Perspective

    PubMed Central

    Lee, B. Q.; Kibédi, T.; Stuchbery, A. E.; Robertson, K. A.

    2012-01-01

    Auger electrons emitted in nuclear decay offer a unique tool to treat cancer cells at the scale of a DNA molecule. Over the last forty years many aspects of this promising research goal have been explored, however it is still not in the phase of serious clinical trials. In this paper, we review the physical processes of Auger emission in nuclear decay and present a new model being developed to evaluate the energy spectrum of Auger electrons, and hence overcome the limitations of existing computations. PMID:22924061

  8. Atomic radiations in the decay of medical radioisotopes: a physics perspective.

    PubMed

    Lee, B Q; Kibédi, T; Stuchbery, A E; Robertson, K A

    2012-01-01

    Auger electrons emitted in nuclear decay offer a unique tool to treat cancer cells at the scale of a DNA molecule. Over the last forty years many aspects of this promising research goal have been explored, however it is still not in the phase of serious clinical trials. In this paper, we review the physical processes of Auger emission in nuclear decay and present a new model being developed to evaluate the energy spectrum of Auger electrons, and hence overcome the limitations of existing computations.

  9. Physical bounds of metallic nanofingers obtained by mechano-chemical atomic force microscope nanolithography

    NASA Astrophysics Data System (ADS)

    Akhavan, O.; Abdolahad, M.

    2009-01-01

    To obtain metallic nanofingers applicable in surface acoustic wave (SAW) sensors, a mechano-chemical atomic force microscope (AFM) nanolithography on a metallic thin film (50 nm in thickness)/piezoelectric substrate covered by a spin-coated polymeric mask layer (50-60 nm in thickness) was implemented. The effective shape of cross-section of the before and after etching grooves have been determined by using the AFM tip deconvolution surface analysis, structure factor, and power spectral density analyses. The wet-etching process improved the shape and aspect ratio (height/width) of the grooves and also smoothed the surface within them. We have shown that the relaxed surface tension of the polymeric mask layer resulted in a down limitation in width and length of the lithographed nanofingers. The surface tension of the mask layer can be changed by altering the initial concentration of the polymer in the deposition process. As the surface tension reduced, the down limitation decreased. In fact, an extrapolation of the analyzed statistical data has indicated that by decreasing the surface tension from 39 to 10 nN/nm, the minimum obtainable width and length of the metallic nanofingers was changed from about 55 nm and 2 μm to 15 nm and 0.44 μm, respectively. Using the extrapolation's results, we have shown that the future SAW sensors buildable by this nanolithography method possess a practical bound in their synchronous frequency (˜58 GHz), mass sensitivity (˜6125 MHz-mm 2/ng), and the limit of mass resolution (˜4.88 × 10 -10 ng/mm 2).

  10. Metal intoxication in humans assessed by atomic and nuclear physics techniques

    NASA Astrophysics Data System (ADS)

    Chettle, David R.

    1995-08-01

    Toxic trace elements such as lead (Pb) and Cadmium (Cd) can be measured non-invasively in humans by radiation physics techniques, particularly x-ray fluorescence and neutron activation. An analysis is usually made of the content of a particular organ, representing the principal storage site of the element in question. For example, Pb is measured in bone, whereas Cd is measured in liver and kidney. Measuring stored quantities of these elements has contributed to assessment of health effects of chronic occupational and environmental exposure. In addition knowledge of the elemental metabolism has been significantly extended. Results of in vivo studies have also contributed to assessment and regulation of workplace exposure. Analogous methods are in use or under development for in vivo assay of mercury, aluminum, gold, platinum, and manganese. The principles of these measurements will be outlined and illustrative applications for Pb and Cd will be discussed.

  11. Gaining insight into the physics of dynamic atomic force microscopy in complex environments using the VEDA simulator.

    PubMed

    Kiracofe, Daniel; Melcher, John; Raman, Arvind

    2012-01-01

    Dynamic atomic force microscopy (dAFM) continues to grow in popularity among scientists in many different fields, and research on new methods and operating modes continues to expand the resolution, capabilities, and types of samples that can be studied. But many promising increases in capability are accompanied by increases in complexity. Indeed, interpreting modern dAFM data can be challenging, especially on complicated material systems, or in liquid environments where the behavior is often contrary to what is known in air or vacuum environments. Mathematical simulations have proven to be an effective tool in providing physical insight into these non-intuitive systems. In this article we describe recent developments in the VEDA (virtual environment for dynamic AFM) simulator, which is a suite of freely available, open-source simulation tools that are delivered through the cloud computing cyber-infrastructure of nanoHUB (www.nanohub.org). Here we describe three major developments. First, simulations in liquid environments are improved by enhancements in the modeling of cantilever dynamics, excitation methods, and solvation shell forces. Second, VEDA is now able to simulate many new advanced modes of operation (bimodal, phase-modulation, frequency-modulation, etc.). Finally, nineteen different tip-sample models are available to simulate the surface physics of a wide variety different material systems including capillary, specific adhesion, van der Waals, electrostatic, viscoelasticity, and hydration forces. These features are demonstrated through example simulations and validated against experimental data, in order to provide insight into practical problems in dynamic AFM.

  12. Gaining insight into the physics of dynamic atomic force microscopy in complex environments using the VEDA simulator

    NASA Astrophysics Data System (ADS)

    Kiracofe, Daniel; Melcher, John; Raman, Arvind

    2012-01-01

    Dynamic atomic force microscopy (dAFM) continues to grow in popularity among scientists in many different fields, and research on new methods and operating modes continues to expand the resolution, capabilities, and types of samples that can be studied. But many promising increases in capability are accompanied by increases in complexity. Indeed, interpreting modern dAFM data can be challenging, especially on complicated material systems, or in liquid environments where the behavior is often contrary to what is known in air or vacuum environments. Mathematical simulations have proven to be an effective tool in providing physical insight into these non-intuitive systems. In this article we describe recent developments in the VEDA (virtual environment for dynamic AFM) simulator, which is a suite of freely available, open-source simulation tools that are delivered through the cloud computing cyber-infrastructure of nanoHUB (www.nanohub.org). Here we describe three major developments. First, simulations in liquid environments are improved by enhancements in the modeling of cantilever dynamics, excitation methods, and solvation shell forces. Second, VEDA is now able to simulate many new advanced modes of operation (bimodal, phase-modulation, frequency-modulation, etc.). Finally, nineteen different tip-sample models are available to simulate the surface physics of a wide variety different material systems including capillary, specific adhesion, van der Waals, electrostatic, viscoelasticity, and hydration forces. These features are demonstrated through example simulations and validated against experimental data, in order to provide insight into practical problems in dynamic AFM.

  13. Ultracold atoms and their applications (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 28 October 2015)

    NASA Astrophysics Data System (ADS)

    2016-02-01

    A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS), "Ultracold atoms and their applications", was held in the conference hall of the Lebedev Physical Institute, RAS, on 28 October 2015.The papers collected in this issue were written based on talks given at the session:(1) Vishnyakova G A, Golovizin A A, Kalganova E S, Tregubov D O, Khabarova K Yu (Lebedev Physical Institute, Russian Academy of Sciences, Moscow; Moscow Institute of Physics and Technology (State University), Dolgoprudnyi, Moscow region), Sorokin V N, Sukachev D D, Kolachevsky N N (Lebedev Physical Institute, Russian Academy of Sciences, Moscow) "Ultracold lanthanides: from optical clock to a quantum simulator"; (2) Barmashova T V, Martiyanov K A, Makhalov V B (Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod), Turlapov A V (Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod; Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod) "Fermi liquid to Bose condensate crossover in a two-dimensional ultracold gas experiment"; (3) Taichenachev A V, Yudin V I, Bagayev S N (Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk; Novosibirsk State University, Novosibirsk) "Ultraprecise optical frequency standards based on ultracold atoms: state of the art and prospects"; (4) Ryabtsev I I, Beterov I I, Tretyakov D B, Entin V M, Yakshina E A (Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk; Novosibirsk State University, Novosibirsk) "Spectroscopy of cold rubidium Rydberg atoms for applications in quantum information". • Ultracold lanthanides: from optical clock to a quantum simulator, G A Vishnyakova, A A Golovizin, E S Kalganova, V N Sorokin, D D Sukachev, D O Tregubov, K Yu Khabarova, N N Kolachevsky Physics-Uspekhi, 2016, Volume 59, Number 2, Pages 168-173 • Fermi liquid-to-Bose condensate crossover in a two

  14. The Light at the End of the Tunnel: Uncertainties in Atomic Physics, Bayesian Inference, and the Analysis of Solar and Stellar Observations

    NASA Astrophysics Data System (ADS)

    Warren, Harry

    2016-05-01

    We report on the efforts of a multidisciplinary International Space Science Institute team that is investigating the limits of our ability to infer the physical properties of solar and stellar atmospheres from remote sensing observations. As part of this project we have estimated the uncertainties in the collisional cross sections and radiative decay rates for Fe XIII and O VII and created 1000 realizations of the CHIANTI atomic database. These perturbed atomic data are then used to analyze solar observations from the EIS spectrometer on Hinode and stellar observations from the LETG on Chandra within a Bayesian framework. For the solar case we find that the systematic errors from the atomic physics dominate the statistical uncertainties from the observations. For many cases the uncertainties are about 10 times larger when variations in the atomic data are included. This indicates the need for very accurate atomic physics. Comparisons among recent Fe XIII calculations suggest that for some transitions the collision rates are currently known well enough to measure the electron density and emission measure to about 15%.

  15. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions.

    PubMed

    Elliot, Alan J; Malek, Gary A; Lu, Rongtao; Han, Siyuan; Yu, Haifeng; Zhao, Shiping; Wu, Judy Z

    2014-07-01

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al2O2/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ~1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al2O3 tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  16. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions

    SciTech Connect

    Elliot, Alan J. E-mail: jwu@ku.edu; Malek, Gary A.; Lu, Rongtao; Han, Siyuan; Wu, Judy Z. E-mail: jwu@ku.edu; Yu, Haifeng; Zhao, Shiping

    2014-07-15

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al{sub 2}O{sub 2}/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ∼1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al{sub 2}O{sub 3} tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  17. High Atom Number in Microsized Atom Traps

    DTIC Science & Technology

    2015-12-14

    2012 conference of the Division of Atomic , Molecular, and Optical Physics (DAMOP) of the American Physical Society (APS). We have reconfigured the...Final Performance Report on ONR Grant N00014-12-1-0608 High atom number in microsized atom traps for the period 15 May 2012 through 14 September...2015 J. M. Grossman Department of Physics St. Mary’s College of Maryland 18952 E. Fisher Road St. Mary’s City, MD 20686 jmgrossman @smcm. edu

  18. An investigation into the effect of spray drying temperature and atomizing conditions on miscibility, physical stability, and performance of naproxen-PVP K 25 solid dispersions.

    PubMed

    Paudel, Amrit; Loyson, Yves; Van den Mooter, Guy

    2013-04-01

    The present study investigates the effect of changing spray drying temperature (40°C-120°C) and/or atomizing airflow rate (AR; 5-15 L/min) on the phase structure, physical stability, and performance of spray-dried naproxen-polyvinylpyrrolidone (PVP) K 25 amorphous solid dispersions. The modulated differential scanning calorimetry, attenuated total internal reflectance-Fourier transform infrared, and powder X-ray diffractometry (pXRD) studies revealed that higher inlet temperature (IT) or atomization airflow leads to the formation of amorphous-phase-separated dispersions with higher strongly H-bonded and free PVP fractions, whereas that prepared with the lowest IT was more homogeneous. The dispersion prepared with the lowest atomization AR showed trace crystallinity. Upon exposure to 75% relative humidity (RH) for 3 weeks, the phase-separated dispersions generated by spray drying at higher temperature or higher atomization airflow retained relatively higher amorphous drug fraction compared with those prepared at slow evaporation conditions. The humidity-controlled pXRD analysis at 98% RH showed that the dispersion prepared with highest atomization AR displayed the slowest kinetics of recrystallization. The molecular-level changes occurring during recrystallization at 98% RH was elucidated by spectroscopic monitoring at the same humidity. The rate and extent of the drug dissolution was the highest for dispersions prepared at the highest atomizing AR and the lowest for that prepared with the slowest atomizing condition.

  19. A Reconstruction of Structure of the Atom and Its Implications for General Physics Textbooks: A History and Philosophy of Science Perspective

    ERIC Educational Resources Information Center

    Rodriguez, Maria A.; Niaz, Mansoor

    2004-01-01

    Recent research in science education has recognized the importance of history and philosophy of science. The objective of this study is to evaluate the presentation of the Thomson, Rutherford, and Bohr models of the atom in general physics textbooks based on criteria derived from history and philosophy of science. Forty-one general physics…

  20. A Reconstruction of Structure of the Atom and Its Implications for General Physics Textbooks: A History and Philosophy of Science Perspective

    ERIC Educational Resources Information Center

    Rodriguez, Maria A.; Niaz, Mansoor

    2004-01-01

    Recent research in science education has recognized the importance of history and philosophy of science. The objective of this study is to evaluate the presentation of the Thomson, Rutherford, and Bohr models of the atom in general physics textbooks based on criteria derived from history and philosophy of science. Forty-one general physics…

  1. PREFACE: The 19th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases Preface: The 19th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases

    NASA Astrophysics Data System (ADS)

    Gordillo-Vazquez, F. J.

    2009-07-01

    The 19th Europhysics Sectional Conference on the Atomic and Molecular Physics of Ionized Gases (ESCAMPIG-2008) took place in Granada (Spain) from 15 to 19 July 2008. The conference was mainly organized by the Spanish National Research Council (CSIC), with the collaboration and support of the University of Córdoba (UCO) and the Research Center for Energy, Environment and Technology (CIEMAT). It is already 35 years since the first ESCAMPIG in 1973. The first editions of ESCAMPIG were in consecutive years (1973 and 1974) but later on it became a biennial conference of the European Physical Society (EPS) initially focusing on the collisional and radiative atomic and molecular processes in low temperature plasmas. The successive ESCAMPIGs took place in Bratislava in 1976 (3rd), Essen in 1978 (4th), Dubrovnik in 1980 (5th) and so on until the last one organized in Granada in 2008 (19th), the first ESCAMPIG in Spain. A number of changes have taken place in the Granada edition of ESCAMPIG. First, the previous six topics that have remained unchanged for almost two decades (since 1990) have now been updated to become twelve new topics which, in the opinion of the International Scientific Committee (ISC), will enhance the opportunity for discussions and communication of new findings and developments in the field of low temperature plasmas. The new list of topics for ESCAMPIG is: • Atomic and molecular processes in plasmas • Transport phenomena, particle velocity distribution function • Physical basis of plasma chemistry • Plasma surface interaction (boundary layers, sheath, surface processes) • Plasma diagnostics • Plasma and dicharges theory and simulation • Self-organization in plasmas, dusty plasmas • Upper atmospheric plasmas and space plasmas • Low pressure plasma sources • High pressure plasma sources • Plasmas and gas flows • Laser produced plasmas Secondly, a new prize has been created, the `William Crookes' prize in Plasma Physics to be

  2. EDITORIAL: The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases The 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran Lj; Marić, Dragana; Malović, Gordana

    2011-03-01

    This special issue consists of papers that are associated with invited lectures, workshop papers and hot topic papers presented at the 20th European Sectional Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG XX). This conference was organized in Novi Sad (Serbia) from 13 to 17 July 2010 by the Institute of Physics of the University of Belgrade. It is important to note that this is not a conference 'proceedings'. Following the initial selection process by the International Scientific Committee, all papers were submitted to the journal by the authors and have been fully peer reviewed to the standard required for publication in Plasma Sources Science and Technology (PSST). The papers are based on presentations given at the conference but are intended to be specialized technical papers covering all or part of the topic presented by the author during the meeting. The ESCAMPIG conference is a regular biennial Europhysics Conference of the European Physical Society focusing on collisional and radiative aspects of atomic and molecular physics in partially ionized gases as well as on plasma-surface interaction. The conference focuses on low-temperature plasma sciences in general and includes the following topics: Atomic and molecular processes in plasmas Transport phenomena, particle velocity distribution function Physical basis of plasma chemistry Plasma surface interaction (boundary layers, sheath, surface processes) Plasma diagnostics Plasma and discharges theory and simulation Self-organization in plasmas, dusty plasmas Upper atmospheric plasmas and space plasmas Low-pressure plasma sources High-pressure plasma sources Plasmas and gas flows Laser-produced plasmas During ESCAMPIG XX special sessions were dedicated to workshops on: Atomic and molecular collision data for plasma modeling, organized by Professors Z Lj Petrovic and N Mason Plasmas in medicine, organized by Dr N Puac and Professor G Fridman. The conference topics were represented in the

  3. Mechanical, thermal, and physical properties of Mg-Ca compounds in the framework of the modified embedded-atom method.

    PubMed

    Groh, Sébastien

    2015-02-01

    Interatomic potentials for pure Ca and the Mg-Ca binary have been developed in the framework of the second nearest-neighbors modified embedded-atom method (MEAM). The validity and the transferability of the Ca MEAM potential was performed by calculating physical, mechanical, and thermal properties. These properties were compared to experimental data and numerical data obtained from existing Ca potentials, and a good agreement was found. In addition, the dissociation of the edge dislocation into two Shockley partials aligns with the linear elasticity solution. Furthermore, the velocity of an edge dislocation under static and dynamics loading conditions predicted in Ca using the MEAM formalism reproduces the expected behavior of an edge dislocation in fcc crystal structures. The Ca MEAM potential was then coupled to an existing Mg MEAM potential to describe the properties of the Mg-Ca alloys. Heat of formation, structural energy difference, and elastic constants were calculated for several ordered Mg-Ca compounds containing different concentrations of Ca. As expected from first-principle calculations based on DFT, Mg2Ca with the Laves phase C14 was found to be the most stable structure with the lowest heat of formation compared to compounds with other Ca concentrations (Mg3Ca, MgCa, and MgCa3). Moreover, the mechanical stability was recovered for the different tested compounds and is in agreement with first-principle data.

  4. Physical properties at the base for the development of an all-atom force field for ethylene glycol.

    PubMed

    Szefczyk, Borys; Cordeiro, M Natália D S

    2011-03-31

    Ethylene glycol, the simplest of the diols, is a popular solvent, an antifreeze agent, a coolant, and a precursor in polymer production. In molecular modeling it is a model compound used to develop potentials for complex systems, like sugars. Despite the fact that many force fields for ethylene glycol exist in the literature, only few of them have been designed to reproduce the macroscopic properties of glycol and its mixtures, and rather more attention has been paid to the microscopic structure of the liquid. Those potentials that reproduce the properties accurately, apply also nonstandard fudge factors, therefore are not fully compatible with any popular force field. In this paper, we present a new potential for ethylene glycol, based on the OPLS all-atom force field and fully compatible with it, as well as with popular models for water. This potential is carefully validated against a broad range of physical properties measured experimentally and published in the literature. These properties include the density, expansion coefficient, compressibility, enthalpy of vaporization, surface tension, self-diffusion coefficient, and viscosity. Therefore, the potential presented here may be used in simulations of not only pure glycol but also mixtures with water, organic solvents, ionic liquids, phase interfaces, etc.

  5. The Nature of Atoms.

    ERIC Educational Resources Information Center

    Holden, Alan

    This monograph was written for the purpose of presenting physics to college students who are not preparing for careers in physics. It deals with the nature of atoms, and treats the following topics: (1) the atomic hypothesis, (2) the chemical elements, (3) models of an atom, (4) a particle in a one-dimensional well, (5) a particle in a central…

  6. Physics.

    PubMed

    Bromley, D A

    1980-07-04

    From massive quarks deep in the hearts of atomic nuclei to the catastrophic collapse of giant stars in the farthest reaches of the universe, from the partial realization of Einstein's dream of a unified theory of the forces of nature to the most practical applications in technology, medicine, and throughout contemporary society, physics continues to have a profound impact on man's view of the universe and on the quality of life. The author argues that the past few years, in terms of new discoveries, new insight-and the new questions-have been among the most productive in the history of the field and puts into context his selection of some of the most important new developments in this fundamental science.

  7. Atom Skimmers and Atom Lasers Utilizing Them

    NASA Technical Reports Server (NTRS)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  8. Lars Onsager Prize Talk: A New Challenge for Cold Atom Physics: Achieving the Strongly Correlated Regimes for Cold Atoms in Optical Lattices.

    NASA Astrophysics Data System (ADS)

    Ho, Tin-Lun

    2008-03-01

    Cold atoms in optical lattices show great promise to generate a whole host of new strongly correlated states and to emulate many theoretical models for strongly interacting electronic systems. However, to reach these strongly correlated regimes, we need to reach unprecedented low temperatures within current experimental settings. To achieve this, it is necessary to remove considerable amount of entropy from the system. Here, we point out a general principle for removing entropies of quantum gases in optical lattices which will allow one to reach some extraordinarily low temperature scales.

  9. The physics of non-Newtonian liquid slurry atomization. Part 2: Twin-fluid atomization of non-Newtonian liquids -- First quarterly technical report, 1 January--31 March 1994

    SciTech Connect

    Mansour, A.; Chigier, N.

    1994-06-01

    The changes in the physical processes of atomization as a result of adding a high molecular weight polymer in low concentrations to liquid have been studied. Both Newtonian and non-Newtonian liquids were investigated with particular emphasis on the non-Newtonian rheological characteristics. It was found that viscoelastic liquids are much more difficult to atomize than viscoinelastic liquids. Viscoinelastic liquids showed a breakup behavior similar to that of water sprays. Viscoelastic materials showed remarkably different breakup patterns. The ligaments were seen to undergo a very large stretching motion before they breakup, resulting in long threads of liquid attached to droplets. The normal stresses developed in viscoelastic materials are much higher than their associated shear stresses. Consequently, the development of the large normal stresses appears to be the most important rheological mechanism that inhibits breakup. The non-Newtonian liquids selected for the experiment were aqueous solutions of Xanthan gum and Polyacrylamide E10.

  10. Acquire an Bruker Dimension FastScan (trademark) Atomic Force Microscope (AFM) for Materials, Physical and Biological Science Research and Education

    DTIC Science & Technology

    2016-04-14

    Force Microscope (AFM) in 2015.The AFM instrument was installed in June 2015 and is greatly promoting our scientific research work and education programs...UU 14-04-2016 1-Jan-2015 31-Jan-2016 Final Report: Acquire an Bruker Dimension FastScanTM Atomic Force Microscope (AFM) for Materials, Physical and...Biological Science Research and Education The views, opinions and/or findings contained in this report are those of the author(s) and should not

  11. Exotic Atoms and Muonium

    NASA Astrophysics Data System (ADS)

    Horváth, D.

    In exotic atoms, one of the atomic electrons is replaced by a negatively charged particle, whereas muonium consists of a positive muon and an electron. After a general review of the theoretical and experimental aspects, the present knowledge of this field is summarized. These include muonium and the application of the muon spin resonance method in solid-state physics and chemistry, muonic hydrogen atoms, muonic molecules and muon-catalyzed fusion, pionic hydrogen atoms and their use in chemistry, testing quantum electrodynamics on heavy muonic atoms, measuring particle and nuclear properties using hadronic atoms, and testing basic symmetry principles with antiprotonic helium atoms and antihydrogen.

  12. Improving fundamental abilities of atomic force microscopy for investigating quantitative nanoscale physical properties of complex biological systems

    NASA Astrophysics Data System (ADS)

    Cartagena-Rivera, Alexander X.

    Measurements of local material properties of complex biological systems (e.g. live cells and viruses) in their respective physiological conditions are extremely important in the fields of biophysics, nanotechnology, material science, and nanomedicine. Yet, little is known about the structure-function-property relationship of live cells and viruses. In the case of live cells, the measurements of progressive variations in viscoelastic properties in vitro can provide insight to the mechanistic processes underpinning morphogenesis, mechano-transduction, motility, metastasis, and many more fundamental cellular processes. In the case of living viruses, the relationship between capsid structural framework and the role of the DNA molecule interaction within viruses influencing their stiffness, damping and electrostatic properties can shed light in virological processes like protein subunits assembly/dissassembly, maturation, and infection. The study of mechanics of live cells and viruses has been limited in part due to the lack of technology capable of acquiring high-resolution (nanoscale, subcellular) images of its heterogeneous material properties which vary widely depending on origin and physical interaction. The capabilities of the atomic force microscope (AFM) for measuring forces and topography with sub-nm precision have greatly contributed to research related to biophysics and biomechanics during the past two decades. AFM based biomechanical studies have the unique advantage of resolving/mapping spatially the local material properties over living cells and viruses. However, conventional AFM techniques such as force-volume and quasi-static force-distance curves are too low resolution and low speed to resolve interesting biophysical processes such as cytoskeletal dynamics for cells or assembly/dissasembly of viruses. To overcome this bottleneck, a novel atomic force microscopy mode is developed, that leads to sub-10-nm resolution and sub-15-minutes mapping of local

  13. Reviews Book: Sustainable Energy—Without the Hot Air Equipment: Doppler Effect Unit Book: The Physics of Rugby Book: Plastic Fantastic: How the Biggest Fraud in Physics Shook the Scientific World Equipment: Brunel Eyecam Equipment: 200x Digital Microscope Book: The Atom and the Apple: Twelve Tales from Contemporary Physics Book: Physics 2 for OCR Web Watch

    NASA Astrophysics Data System (ADS)

    2009-09-01

    WE RECOMMEND Sustainable Energy—Without the Hot Air This excellent book makes sense of energy facts and figures Doppler Effect Unit Another simple, effective piece of kit from SEP Plastic Fantastic: How the Biggest Fraud in Physics Shook the Scientific World Intriguing and unique write-up of an intellectual fraud case Brunel Eyecam An affordable digital eyepiece for your microscope 200x Digital Microscope An adjustable digital flexcam for classroom use The Atom and the Apple: Twelve Tales from Contemporary Physics A fascinating round-up of the recent history of physics WORTH A LOOK The Physics of Rugby Book uses sport analogy and context to teach physics concepts Physics 2 for OCR Essential textbook for the course but otherwise pointless WEB WATCH Some free teaching materials are better than those you'd pay for

  14. Atom Interferometry

    ScienceCinema

    Mark Kasevich

    2016-07-12

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  15. Atom Interferometry

    SciTech Connect

    Mark Kasevich

    2008-05-07

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  16. Atom Interferometry

    SciTech Connect

    Kasevich, Mark

    2008-05-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  17. Images of Atoms.

    ERIC Educational Resources Information Center

    Wright, Tony

    2003-01-01

    Recommends using a simple image, such as the fuzzy atom ball to help students develop a useful understanding of the molecular world. Explains that the image helps students easily grasp ideas about atoms and molecules and leads naturally to more advanced ideas of atomic structure, chemical bonding, and quantum physics. (Author/NB)

  18. Images of Atoms.

    ERIC Educational Resources Information Center

    Wright, Tony

    2003-01-01

    Recommends using a simple image, such as the fuzzy atom ball to help students develop a useful understanding of the molecular world. Explains that the image helps students easily grasp ideas about atoms and molecules and leads naturally to more advanced ideas of atomic structure, chemical bonding, and quantum physics. (Author/NB)

  19. 2004 Rahman Prize in Computational Physics: HOW DO SOLIDS FAIL? A Research Adventure Using Lots Of Atoms And Big Computers

    NASA Astrophysics Data System (ADS)

    Abraham, Farid

    2004-03-01

    During the last decade, I have been simulating the dynamic failure of brittle and ductile solids at the atomic level using millions of atoms and some of the world's fastest computers. Computer experiments encompassing crack dynamics in brittle fracture, crack blunting in ductile failure, and dislocation entanglement in work-hardening are some examples and have given new and exciting insights into the failure processes of solids. My goal is to give the audience an appreciation for the power of atomistic simulations, coupled with visualization, in studying "how solids fail."

  20. Fermion zero modes in a Z2 vortex background

    NASA Astrophysics Data System (ADS)

    Lozano, Gustavo; Mohammadi, Azadeh; Schaposnik, Fidel A.

    2016-09-01

    In this paper we study the zero energy solutions of the Dirac equation in the background of a Z2 vortex of a non-Abelian gauge model with three charged scalar fields. We determine the number of the fermionic zero modes giving their explicit form for two specific Ansätze.

  1. Greek Atomic Theory.

    ERIC Educational Resources Information Center

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  2. Greek Atomic Theory.

    ERIC Educational Resources Information Center

    Roller, Duane H. D.

    1981-01-01

    Focusing on history of physics, which began about 600 B.C. with the Ionian Greeks and reaching full development within three centuries, suggests that the creation of the concept of the atom is understandable within the context of Greek physical theory; so is the rejection of the atomic theory by the Greek physicists. (Author/SK)

  3. The physics of coal liquid slurry atomization. Annual topical report, 14 March 1993--14 March 1994

    SciTech Connect

    Chigier, N.

    1994-06-01

    The stability of turbulent columns of liquid injected into a quiescent environment has been studied. Turbulence decay along Newtonian jets was investigated along with the effects of turbulence on the resulting droplet size distributions after breakup. Disintegration of liquid jets injected into a high-velocity gas stream has also been studied. Newtonian and non-Newtonian liquids were studied with particular emphasis on the non-Newtonian rheological characteristics. Determination was made of the extent that the addition of high molecular weight polymer to liquids changes the breakup process. Shear thinning, extension thinning and extension thickening fluids were investigated. The non-Newtonian viscosities were measured over five decades of shear rates for 12 solutions of polymeric materials. By using the die-swell technique, the first normal stress difference was determined for all solutions. By using the contraction flow technique, the extensional viscosity levels were determined for the most viscous solutions. The near field produced by a co-axial airblast atomizer was investigated using the phase Doppler particle analyzer. The classical wave mechanism and empirical models reported for air-blast atomization of low viscosity liquid were shown to be applicable to air-blast atomization of viscous non-Newtonian liquids. The theoretical basis of several models which give the best fit to the experimental data for air-blast atomization of non-Newtonian liquids was addressed. Conclusions to date are discussed for the following areas: Turbulence characteristics in liquid jets; The effect of turbulence on the stability of liquid columns; The rheology of mobile polymeric solutions; and Air blast atomization of non-Newtonian liquids.

  4. Constraining extra neutral gauge bosons with atomic parity violation measurements

    NASA Astrophysics Data System (ADS)

    Diener, Ross; Godfrey, Stephen; Turan, Ismail

    2012-12-01

    The discovery of a new neutral gauge boson Z' could provide the first concrete evidence of physics beyond the standard model. We explore how future parity violation experiments, especially atomic parity violation experiments, can be used to constrain Z' bosons. We use the recent measurement of the Cs133 nuclear weak charge to estimate lower bounds on the mass of Z' bosons for a number of representative models and to put constraints on the couplings of a newly discovered Z' boson. We also consider how these constraints might be improved by future atomic parity violation experiments that will measure nuclear weak charges of multiple isotopes. We show how measurements of a single isotope and combining measurements into ratios and differences can be used to constrain the couplings of a Z' and discriminate between models. We include in our results the constraints that can be obtained from the experiments Qweak and P2 that measure the proton weak charge. We find that current and future parity violation experiments could potentially play an important role in unravelling new physics if a Z' were discovered.

  5. News UK public libraries offer walk-in access to research Atoms for Peace? The Atomic Weapons Establishment and UK universities Students present their research to academics: CERN@school Science in a suitcase: Marvin and Milo visit Ethiopia Inspiring telescopes A day for everyone teaching physics 2014 Forthcoming Events

    NASA Astrophysics Data System (ADS)

    2014-05-01

    UK public libraries offer walk-in access to research Atoms for Peace? The Atomic Weapons Establishment and UK universities Students present their research to academics: CERN@school Science in a suitcase: Marvin and Milo visit Ethiopia Inspiring telescopes A day for everyone teaching physics 2014 Forthcoming Events

  6. Structural polymorphism in the L1 loop regions of human H2A.Z.1 and H2A.Z.2

    PubMed Central

    Horikoshi, Naoki; Sato, Koichi; Shimada, Keisuke; Arimura, Yasuhiro; Osakabe, Akihisa; Tachiwana, Hiroaki; Hayashi-Takanaka, Yoko; Iwasaki, Wakana; Kagawa, Wataru; Harata, Masahiko; Kimura, Hiroshi; Kurumizaka, Hitoshi

    2013-01-01

    The histone H2A.Z variant is widely conserved among eukaryotes. Two isoforms, H2A.Z.1 and H2A.Z.2, have been identified in vertebrates and may have distinct functions in cell growth and gene expression. However, no structural differences between H2A.Z.1 and H2A.Z.2 have been reported. In the present study, the crystal structures of nucleosomes containing human H2A.Z.1 and H2A.Z.2 were determined. The structures of the L1 loop regions were found to clearly differ between H2A.Z.1 and H2A.Z.2, although their amino-acid sequences in this region are identical. This structural polymorphism may have been induced by a substitution that evolutionally occurred at the position of amino acid 38 and by the flexible nature of the L1 loops of H2A.Z.1 and H2A.Z.2. It was also found that in living cells nucleosomal H2A.Z.1 exchanges more rapidly than H2A.Z.2. A mutational analysis revealed that the amino-acid difference at position 38 is at least partially responsible for the distinctive dynamics of H2A.Z.1 and H2A.Z.2. These findings provide important new information for understanding the differences in the regulation and functions of H2A.Z.1 and H2A.Z.2 in cells. PMID:24311584

  7. Inner-shell ionization of atomic targets by Electron Impact

    NASA Astrophysics Data System (ADS)

    Haque, A. K. F.; Talukder, M. R.; Shahjahan, M.; Uddin, M. A.; Basak, A. K.; Saha, B. C.

    2010-03-01

    The knowledge of inner-shell ionization cross sections has not only fundamental importance for understanding collision dynamics of electron-atom interactions, etc, but also is used extensively in many applied fields such as radiation science, astrophysics, plasma physics, etc. The enormous demands of ionization cross sections can only be met by suitable analytical formula that are easy to use and can produce reliable result. We report here an extension of the CVTS [1] model incorporating both the relativistic and ionic factors and tested on 23 atomic targets ranging from He to U [2] with excellent account of the experimental cross sections. [4pt] [1] C. S. Campos, M. A. Z. Vasconcellos, J. C. Trincavelli, and S. Segui, J. Phys. B. 40, 3835 (2007).[0pt] [2] A K F Haque, M R Talukder, M. Shahjahan, M A Uddin, A K Basak and B C Saha, J. Phys. B.; At. Mol. Opt. Phys (under consideration), (2010).

  8. The Atomic Intrinsic Integration Approach: A Structured Methodology for the Design of Games for the Conceptual Understanding of Physics

    ERIC Educational Resources Information Center

    Echeverria, Alejandro; Barrios, Enrique; Nussbaum, Miguel; Amestica, Matias; Leclerc, Sandra

    2012-01-01

    Computer simulations combined with games have been successfully used to teach conceptual physics. However, there is no clear methodology for guiding the design of these types of games. To remedy this, we propose a structured methodology for the design of conceptual physics games that explicitly integrates the principles of the intrinsic…

  9. The Atomic Intrinsic Integration Approach: A Structured Methodology for the Design of Games for the Conceptual Understanding of Physics

    ERIC Educational Resources Information Center

    Echeverria, Alejandro; Barrios, Enrique; Nussbaum, Miguel; Amestica, Matias; Leclerc, Sandra

    2012-01-01

    Computer simulations combined with games have been successfully used to teach conceptual physics. However, there is no clear methodology for guiding the design of these types of games. To remedy this, we propose a structured methodology for the design of conceptual physics games that explicitly integrates the principles of the intrinsic…

  10. Flawed Nuclear Physics and Atomic Intelligence in the Campaign to deny Norwegian Heavy Water to Germany, 1942-1944

    NASA Astrophysics Data System (ADS)

    Børresen, Hans Christofer

    2012-12-01

    The military campaign to deny Norwegian heavy water to Germany in World War II did not diminish as the threat posed by heavy water in German hands dwindled, mainly because of excessive security among the Allies. Signs that Albert Speer (1905-1981) had decided in 1942 to stop the German atomic-bomb project were kept secret and ignored. Prominent Allied advisers like Leif Tronstad (1903-1945) and even Niels Bohr (1885-1962) were not told about the plutonium path to a German atomic bomb. Physicists did not brief advisers, decision makers, and Allied officers on how many years Werner Heisenberg (1901-1976) would need to accumulate enough heavy water (deuterium oxide, D2O) for an Uranmachine and then to extract and process plutonium for an atomic bomb. Had the flow of information been better, the military raids on the Norwegian heavy-water plant at Vemork could have been timed better, and the more costly of them could have been averted altogether.

  11. Chemistry and physics of a single atomic layer: strategies and challenges for functionalization of graphene and graphene-based materials.

    PubMed

    Yan, Liang; Zheng, Yue Bing; Zhao, Feng; Li, Shoujian; Gao, Xingfa; Xu, Bingqian; Weiss, Paul S; Zhao, Yuliang

    2012-01-07

    Graphene has attracted great interest for its superior physical, chemical, mechanical, and electrical properties that enable a wide range of applications from electronics to nanoelectromechanical systems. Functionalization is among the significant vectors that drive graphene towards technological applications. While the physical properties of graphene have been at the center of attention, we still lack the knowledge framework for targeted graphene functionalization. In this critical review, we describe some of the important chemical and physical processes for graphene functionalization. We also identify six major challenges in graphene research and give perspectives and practical strategies for both fundamental studies and applications of graphene (315 references).

  12. X-ray sources such as metallic liner inside plastic cavities are used to test atomic physics models for LMJ simulations

    NASA Astrophysics Data System (ADS)

    Girard, Frederic; Jacquet, L.; Primout, M.; Babonneau, D.; Villette, B.; Stemmler, Ph.

    2009-11-01

    Bright multi-keV K-shell emission sources [1-3] are necessary for ICF studies such as radiography of dense materials. Our recent works with titanium (Heα at 4.7 keV) and germanium (Heα at 10.3 keV) lined cavities showed very high multi-keV x-ray conversion efficiencies up to 14.0% and 0.8% (respectively) [3]. Cavities with a titanium, copper or germanium liner have been used on the OMEGA laser facility in Rochester to test specifically atomic physics models coupled to hydrodynamic codes. Simulation results differ significantly from experimental conversion efficiencies for titanium liner but they are close together for germanium one. Atomic physics models do have great impact on X-ray output. The need for accurate predictive simulation is important in order to set up relevant radiography sources for experiments on the path to ignition. Multi-keV emission is diagnosed by a full set of diagnostics giving conversion efficiencies, time dependant x-ray power and imaging, time integrated imaging and high resolution spectra of titanium. [4pt] [1] D. Babonneau et al., Phys. Plasmas, 15, 092702, 2008 [0pt] [2] K. B. Fournier et al., Phys. Plasmas, 16 052703, 2009 [0pt] [3] F. Girard et al., Phys. Plasmas, 16, 052704, 2009

  13. Physical/chemical properties of tin oxide thin film transistors prepared using plasma-enhanced atomic layer deposition

    SciTech Connect

    Lee, Byung Kook; Jung, Eunae; Kim, Seok Hwan; Moon, Dae Chul; Lee, Sun Sook; Park, Bo Keun; Hwang, Jin Ha; Chung, Taek-Mo; Kim, Chang Gyoun; An, Ki-Seok

    2012-10-15

    Thin film transistors (TFTs) with tin oxide films as the channel layer were fabricated by means of plasma enhanced atomic layer deposition (PE-ALD). The as-deposited tin oxide films show n-type conductivity and a nano-crystalline structure of SnO{sub 2}. Notwithstanding the relatively low deposition temperatures of 70, 100, and 130 °C, the bottom gate tin oxide TFTs show an on/off drain current ratio of 10{sup 6} while the device mobility values were increased from 2.31 cm{sup 2}/V s to 6.24 cm{sup 2}/V s upon increasing the deposition temperature of the tin oxide films.

  14. Experiments With Trapped Neutral Atoms

    DTIC Science & Technology

    2010-01-05

    created close links with condensed matter and many body physics. During the funding period, major advances were done towards atom interferometry with Bose...Pulsed Quantum Zeno Effect Atom chips • Long Phase Coherence Time and Number Squeezing of two Bose-Einstein Condensates on an Atom Chip • Phase...This created close links with condensed matter and many body physics. During the funding period, major advances were done towards atom interferometry

  15. Atomic Databases

    NASA Astrophysics Data System (ADS)

    Mendoza, Claudio

    2000-10-01

    Atomic and molecular data are required in a variety of fields ranging from the traditional astronomy, atmospherics and fusion research to fast growing technologies such as lasers, lighting, low-temperature plasmas, plasma assisted etching and radiotherapy. In this context, there are some research groups, both theoretical and experimental, scattered round the world that attend to most of this data demand, but the implementation of atomic databases has grown independently out of sheer necessity. In some cases the latter has been associated with the data production process or with data centers involved in data collection and evaluation; but sometimes it has been the result of individual initiatives that have been quite successful. In any case, the development and maintenance of atomic databases call for a number of skills and an entrepreneurial spirit that are not usually associated with most physics researchers. In the present report we present some of the highlights in this area in the past five years and discuss what we think are some of the main issues that have to be addressed.

  16. Atomic force microscopy: a versatile tool to probe the physical and chemical properties of supported membranes at the nanoscale.

    PubMed

    Picas, Laura; Milhiet, Pierre-Emmanuel; Hernández-Borrell, Jordi

    2012-12-01

    Atomic force microscopy (AFM) was developed in the 1980s following the invention of its precursor, scanning tunneling microscopy (STM), earlier in the decade. Several modes of operation have evolved, demonstrating the extreme versatility of this method for measuring the physicochemical properties of samples at the nanoscopic scale. AFM has proved an invaluable technique for visualizing the topographic characteristics of phospholipid monolayers and bilayers, such as roughness, height or laterally segregated domains. Implemented modes such as phase imaging have also provided criteria for discriminating the viscoelastic properties of different supported lipid bilayer (SLB) regions. In this review, we focus on the AFM force spectroscopy (FS) mode, which enables determination of the nanomechanical properties of membrane models. The interpretation of force curves is presented, together with newly emerging techniques that provide complementary information on physicochemical properties that may contribute to our understanding of the structure and function of biomembranes. Since AFM is an imaging technique, some basic indications on how real-time AFM imaging is evolving are also presented at the end of this paper. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  17. First Results of the GPS.DM Observatory: Search for Dark Matter and Exotic Physics with Atomic Clocks and GPS Constellation

    NASA Astrophysics Data System (ADS)

    Roberts, Benjamin; Blewitt, Geoff; Dailey, Conner; Pospelov, Maxim; Rollings, Alex; Sherman, Jeff; Williams, Wyatt; Derevianko, Andrei; GPS. DM Collaboration

    2017-01-01

    Despite the overwhelming cosmological evidence for the existence of dark matter, and the considerable effort of the scientific community over decades, there is no evidence for dark matter in terrestrial experiments. The GPS.DM observatory uses the existing GPS constellation as a 50,000 km-aperture sensor array, analysing the satellite and terrestrial atomic clock data for exotic physics signatures. In particular, the collaboration searches for evidence of transient variations of fundamental constants correlated with the Earth's galactic motion through the dark matter halo. There already exists more than 10 years of good clock timing data that can be used in the search. This type of search is particularly sensitive to exotic forms of dark matter, such as topological defects. Supported by the NSF.

  18. Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model.

    PubMed

    Solares, Santiago D

    2014-01-01

    This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip-sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip-sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip-sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

  19. Materials at Atomic Pressure

    SciTech Connect

    Hicks, Damien

    2010-06-10

    Atomic units give the scale at which quantum processes operate. As combinations of fundamental constants they concisely encapsulate qualities of the atom, e.g. atomic length and energy scales are given by the Bohr radius and the Hartree (or Rydberg) respectively. Although many of these quantities were probed in the early part of the 20th Century the atomic unit of time, at tens of attoseconds, was first probed in 2001. Today, the only atomic unit that remains to be studied experimentally is the atomic unit of pressure, at 294 Mbar (or 147 Mbar in Rydberg atomic units). This is nature’s definition of the ‘high’ in high-pressure science, and it sets the scale for new physics and chemistry. Among experimental facilities, only the NIF can attain and accurately probe atomic pressures. We propose to directly study material properties at these conditions by examining the short-range ordering of atoms using x-ray absorption fine structure spectroscopy (XAFS) of layers in spherical, ignition-type imploding shells. What happens at atomic pressures? The atomic unit of pressure represents the quantum mechanical pressure exerted by an orbiting electron to prevent collapse into the nucleus. Applying external pressure of this magnitude seriously disrupts orbitals and alters the character of the atom itself. Core electron orbitals overlap and chemical bonds are no longer constrained to occur between valence electron orbitals alone. The most direct probe of bonding requires a short-range order diagnostic such as XAFS.

  20. Physics.

    ERIC Educational Resources Information Center

    Bromley, D. Allan

    1980-01-01

    The author presents the argument that the past few years, in terms of new discoveries, insights, and questions raised, have been among the most productive in the history of physics. Selected for discussion are some of the most important new developments in physics research. (Author/SA)

  1. Physics.

    ERIC Educational Resources Information Center

    Bromley, D. Allan

    1980-01-01

    The author presents the argument that the past few years, in terms of new discoveries, insights, and questions raised, have been among the most productive in the history of physics. Selected for discussion are some of the most important new developments in physics research. (Author/SA)

  2. PREFACE: Papers from the 17th European Conference on Atomic and Molecular Physics of Ionized Gases (Constanta, Romania, 1 5 September 2004)

    NASA Astrophysics Data System (ADS)

    Ciupina, V.; Musa, G.; Vladoiu, R.

    2005-05-01

    The 17th European Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG-17) was held in Constanta, Romania, on 1-5 September 2004. ESCAMPIG is an important biennial European conference at which useful exchanges of ideas and discussion of new achievements in low temperature plasma physics take place. The meeting was held in the ambient location of Constanta, Romania, which provided the perfect location to encourage interaction between the related research communities attending the conference. The local organizers, as well as the plasma scientists of Romania, were all very much honoured that Constanta was selected by the International Scientific Committee as the location for ESCAMPIG-17. The conference was the second largest plasma physics conference ever to take place in Romania, second only to the ICPIG conference of 1969 in Bucharest—a huge conference with four parallel sections and simultaneous translation in four languages (English, German, French and Russian) in all four parallel sections. In contrast, ESCAMPIG-17 maintained the founding ideals and held single sessions only to encourage and strengthen the relationships between research communities. During ESCAMPIG-17 we had the opportunity to attend and hear excellent invited lectures presenting outstanding new results in plasma physics. A selection of those invited lectures from ESCAMPIG-17 is published in this issue of Plasma Sources Science and Technology. We would like to take this opportunity to express our thanks to all the invited lecturers and also to all the participants who attended ESCAMPIG-17. The Local Organizing Committee would particularly like to thank all the International Scientific Committee members. Special thanks are due to Professor Gerrit Kroesen and Professor Nader Sadeghi for their valuable and continuous support in solving our problems, no matter how complicated they were.

  3. Physics of a two-dimensional electron gas with cold atoms in non-Abelian gauge potentials

    NASA Astrophysics Data System (ADS)

    Satija, Indubala I.; Dakin, Daniel C.; Vaishnav, J. Y.; Clark, Charles W.

    2008-04-01

    Motivated by the possibility of creating non-Abelian fields using cold atoms in optical lattices, we explore the richness and complexity of noninteracting two-dimensional electron gases (2DEGs) in a lattice, subjected to such fields. In the continuum limit, a non-Abelian system characterized by a two-component “magnetic flux” describes a harmonic oscillator existing in two different charge states (mimicking a particle-hole pair) where the coupling between the states is determined by the non-Abelian parameter, namely, the difference between the two components of the “magnetic flux.” A key feature of the non-Abelian system is a splitting of the Landau energy levels, which broaden into bands, as the spectrum depends explicitly on the transverse momentum. These Landau bands result in a coarse-grained “moth,” a continuum version of the generalized Hofstadter butterfly. Furthermore, the bands overlap, leading to effective relativistic effects. Importantly, similar features also characterize the corresponding two-dimensional lattice problem when at least one of the components of the magnetic flux is an irrational number. The lattice system with two competing “magnetic fluxes” penetrating the unit cell provides a rich environment in which to study localization phenomena. Some unique aspects of the transport properties of the non-Abelian system are the possibility of inducing localization by varying the quasimomentum, and the absence of localization of certain zero-energy states exhibiting a linear energy-momentum relation. Furthermore, non-Abelian systems provide an interesting localization scenario where the localization transition is accompanied by a transition from relativistic to nonrelativistic theory.

  4. Air-stable cationic gold(I) catalyst featuring a Z-type ligand: promoting enyne cyclizations.

    PubMed

    Inagaki, Fuyuhiko; Matsumoto, Chiaki; Okada, Yasuhiko; Maruyama, Naoya; Mukai, Chisato

    2015-01-12

    An air-stable cationic Au(I) complex featuring a Z-type ligand (boron atom) as a σ-acceptor was developed for elucidating the effect of B on catalytic reactions. An enyne cyclization in the presence of either [Au→B](+) or [Au](+) showed that [Au→B](+) promotes the reactivity, which enabled the effective construction of not only five- and six-membered rings, but also seven-membered rings. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Propagation studies for the construction of atomic macro-coherence in dense media as a tool to investigate neutrino physics

    NASA Astrophysics Data System (ADS)

    Martín Vaquero, J.; Cuevas-Maraver, J.; Peralta Conde, A.

    2017-03-01

    In this manuscript we review the possibility of inducing large coherence in a macroscopic dense target by using adiabatic techniques. For this purpose we investigate the degradation of the laser pulse through propagation, which was also related to the size of the prepared medium. Our results show that, although adiabatic techniques offer the best alternative in terms of stability against experimental parameters, for very dense media it is necessary to engineer laser-matter interaction in order to minimize laser field degradation. This work has been triggered by the proposal of a new technique, namely Radiative Emission of Neutrino Pairs (RENP), capable of investigating neutrino physics through quantum optics concepts which require the preparation of a macrocoherent state.

  6. Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation

    NASA Astrophysics Data System (ADS)

    Yamanaka, N.; Sahoo, B. K.; Yoshinaga, N.; Sato, T.; Asahi, K.; Das, B. P.

    2017-03-01

    The current status of electric dipole moments of diamagnetic atoms which involves the synergy between atomic experiments and three different theoretical areas, i.e. particle, nuclear and atomic, is reviewed. Various models of particle physics that predict CP violation, which is necessary for the existence of such electric dipole moments, are presented. These include the standard model of particle physics and various extensions of it. Effective hadron level combined charge conjugation (C) and parity (P) symmetry violating interactions are derived taking into consideration different ways in which a nucleon interacts with other nucleons as well as with electrons. Nuclear structure calculations of the CP-odd nuclear Schiff moment are discussed using the shell model and other theoretical approaches. Results of the calculations of atomic electric dipole moments due to the interaction of the nuclear Schiff moment with the electrons and the P and time-reversal (T) symmetry violating tensor-pseudotensor electron-nucleus are elucidated using different relativistic many-body theories. The principles of the measurement of the electric dipole moments of diamagnetic atoms are outlined. Upper limits for the nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained combining the results of atomic experiments and relativistic many-body theories. The coefficients for the different sources of CP violation have been estimated at the elementary particle level for all the diamagnetic atoms of current experimental interest and their implications for physics beyond the standard model is discussed. Possible improvements of the current results of the measurements as well as quantum chromodynamics, nuclear and atomic calculations are suggested.

  7. A physics package for rubidium atomic frequency standard with a short-term stability of 2.4 × 10-13 τ-1/2

    NASA Astrophysics Data System (ADS)

    Hao, Qiang; Li, Wenbing; He, Shengguo; Lv, Jianfeng; Wang, Pengfei; Mei, Ganghua

    2016-12-01

    In this article, a new type of physics package with high signal to noise ratio for a rubidium atomic frequency standard is reported. To enhance the clock transition signal, a slotted tube microwave cavity with a field orientation factor of 0.93 and an absorption cell with the diameter of 30 mm were utilized in design of the cavity-cell assembly. Based on the spectral analysis of the three commonly used rubidium spectral lamps, the spectral lamp filled with Xe gas was chosen as the optical pumping source for its small line shape distortion. To suppress the shot noise of the signal, a band pass interference filter was used to filter out Xe spectral lines from the pumping light. A desk system of the rubidium frequency standard with the physics package was realized, and the short-term stability of the system was predicted and tested. The measured result is 2.4 × 10-13 τ-1/2 up to 100 s averaging time, in good agreement with the predicted one.

  8. Can a physics-based, all-atom potential find a protein's native structure among misfolded structures? I. Large scale AMBER benchmarking.

    PubMed

    Wroblewska, Liliana; Skolnick, Jeffrey

    2007-09-01

    Recent work has shown that physics-based, all-atom energy functions (AMBER, CHARMM, OPLS-AA) and local minimization, when used in scoring, are able to discriminate among native and decoy structures. Yet, there have been only few instances reported of the successful use of physics based potentials in the actual refinement of protein models from a starting conformation to one that ends in structures, which are closer to the native state. An energy function that has a global minimum energy in the protein's native state and a good correlation between energy and native-likeness should be able to drive model structures closer to their native structure during a conformational search. Here, the possible reasons for the discrepancy between the scoring and refinement results for the case of AMBER potential are examined. When the conformational search via molecular dynamics is driven by the AMBER potential for a large set of 150 nonhomologous proteins and their associated decoys, often the native minimum does not appear to be the lowest free energy state. Ways of correcting the potential function in order to make it more suitable for protein model refinement are proposed. Copyright 2007 Wiley Periodicals, Inc.

  9. A physics package for rubidium atomic frequency standard with a short-term stability of 2.4 × 10(-13) τ(-1/2).

    PubMed

    Hao, Qiang; Li, Wenbing; He, Shengguo; Lv, Jianfeng; Wang, Pengfei; Mei, Ganghua

    2016-12-01

    In this article, a new type of physics package with high signal to noise ratio for a rubidium atomic frequency standard is reported. To enhance the clock transition signal, a slotted tube microwave cavity with a field orientation factor of 0.93 and an absorption cell with the diameter of 30 mm were utilized in design of the cavity-cell assembly. Based on the spectral analysis of the three commonly used rubidium spectral lamps, the spectral lamp filled with Xe gas was chosen as the optical pumping source for its small line shape distortion. To suppress the shot noise of the signal, a band pass interference filter was used to filter out Xe spectral lines from the pumping light. A desk system of the rubidium frequency standard with the physics package was realized, and the short-term stability of the system was predicted and tested. The measured result is 2.4 × 10(-13) τ(-1/2) up to 100 s averaging time, in good agreement with the predicted one.

  10. Conceptual Design of a Z-Pinch Fusion Propulsion System

    NASA Technical Reports Server (NTRS)

    Adams, Robert; Polsgrove, Tara; Fincher, Sharon; Fabinski, Leo; Maples, Charlotte; Miernik, Janie; Stratham, Geoffrey; Cassibry, Jason; Cortez, Ross; Turner, Matthew; hide

    2010-01-01

    This slide presentation reviews a project that aims to develop a conceptual design for a Z-pinch thruster, that could be applied to develop advanced thruster designs which promise high thrust/high specific impulse propulsion. Overviews shows the concept of the design, which use annular nozzles with deuterium-tritium (D-T) fuel and a Lithium mixture as a cathode, Charts show the engine performance as a function of linear mass, nozzle performance (i.e., plasma segment trajectories), and mission analysis for possible Mars and Jupiter missions using this concept for propulsion. Slides show views of the concepts for the vehicle configuration, thrust coil configuration, the power management system, the structural analysis of the magnetic nozzle, the thermal management system, and the avionics suite,

  11. Crystal structures of heterotypic nucleosomes containing histones H2A.Z and H2A

    PubMed Central

    Horikoshi, Naoki; Arimura, Yasuhiro; Taguchi, Hiroyuki; Kurumizaka, Hitoshi

    2016-01-01

    H2A.Z is incorporated into nucleosomes located around transcription start sites and functions as an epigenetic regulator for the transcription of certain genes. During transcriptional regulation, the heterotypic H2A.Z/H2A nucleosome containing one each of H2A.Z and H2A is formed. However, previous homotypic H2A.Z nucleosome structures suggested that the L1 loop region of H2A.Z would sterically clash with the corresponding region of canonical H2A in the heterotypic nucleosome. To resolve this issue, we determined the crystal structures of heterotypic H2A.Z/H2A nucleosomes. In the H2A.Z/H2A nucleosome structure, the H2A.Z L1 loop structure was drastically altered without any structural changes of the canonical H2A L1 loop, thus avoiding the steric clash. Unexpectedly, the heterotypic H2A.Z/H2A nucleosome is more stable than the homotypic H2A.Z nucleosome. These data suggested that the flexible character of the H2A.Z L1 loop plays an essential role in forming the stable heterotypic H2A.Z/H2A nucleosome. PMID:27358293

  12. Crystal structures of heterotypic nucleosomes containing histones H2A.Z and H2A.

    PubMed

    Horikoshi, Naoki; Arimura, Yasuhiro; Taguchi, Hiroyuki; Kurumizaka, Hitoshi

    2016-06-01

    H2A.Z is incorporated into nucleosomes located around transcription start sites and functions as an epigenetic regulator for the transcription of certain genes. During transcriptional regulation, the heterotypic H2A.Z/H2A nucleosome containing one each of H2A.Z and H2A is formed. However, previous homotypic H2A.Z nucleosome structures suggested that the L1 loop region of H2A.Z would sterically clash with the corresponding region of canonical H2A in the heterotypic nucleosome. To resolve this issue, we determined the crystal structures of heterotypic H2A.Z/H2A nucleosomes. In the H2A.Z/H2A nucleosome structure, the H2A.Z L1 loop structure was drastically altered without any structural changes of the canonical H2A L1 loop, thus avoiding the steric clash. Unexpectedly, the heterotypic H2A.Z/H2A nucleosome is more stable than the homotypic H2A.Z nucleosome. These data suggested that the flexible character of the H2A.Z L1 loop plays an essential role in forming the stable heterotypic H2A.Z/H2A nucleosome. © 2016 The Authors.

  13. Designing quantum-information-processing superconducting qubit circuits that exhibit lasing and other atomic-physics-like phenomena on a chip

    NASA Astrophysics Data System (ADS)

    Nori, Franco

    2008-03-01

    Superconducting (SC) circuits can behave like atoms making transitions between a few energy levels. Such circuits can test quantum mechanics at macroscopic scales and be used to conduct atomic-physics experiments on a silicon chip. This talk overviews a few of our theoretical studies on SC circuits and quantum information processing (QIP) including: SC qubits for single photon generation and for lasing; controllable couplings among qubits; how to increase the coherence time of qubits using a capacitor in parallel to one of the qubit junctions; hybrid circuits involving both charge and flux qubits; testing Bell's inequality in SC circuits; generation of GHZ states; quantum tomography in SC circuits; preparation of macroscopic quantum superposition states of a cavity field via coupling to a SC qubit; generation of nonclassical photon states using a SC qubit in a microcavity; scalable quantum computing with SC qubits; and information processing with SC qubits in a microwave field. Controllable couplings between qubits can be achieved either directly or indirectly. This can be done with and without coupler circuits, and with and without data-buses like EM fields in cavities (e.g., we will describe both the variable-frequency magnetic flux approach and also a generalized double-resonance approach that we introduced). It is also possible to ``turn a quantum bug into a feature'' by using microscopic defects as qubits, and the macroscopic junction as a controller of it. We have also studied ways to implement radically different approaches to QIP by using ``cluster states'' in SC circuits. For a general overview of this field, see, J.Q. You and F. Nori, Phys. Today 58 (11), 42 (2005)

  14. Single atom electrochemical and atomic analytics

    NASA Astrophysics Data System (ADS)

    Vasudevan, Rama

    In the past decade, advances in electron and scanning-probe based microscopies have led to a wealth of imaging and spectroscopic data with atomic resolution, yielding substantial insight into local physics and chemistry in a diverse range of systems such as oxide catalysts, multiferroics, manganites, and 2D materials. However, typical analysis of atomically resolved images is limited, despite the fact that image intensities and distortions of the atoms from their idealized positions contain unique information on the physical and chemical properties inherent to the system. Here, we present approaches to data mine atomically resolved images in oxides, specifically in the hole-doped manganite La5/8Ca3/8MnO3, on epitaxial films studied by in-situ scanning tunnelling microscopy (STM). Through application of bias to the STM tip, atomic-scale electrochemistry is demonstrated on the manganite surface. STM images are then further analyzed through a suite of algorithms including 2D autocorrelations, sliding window Fourier transforms, and others, and can be combined with basic thermodynamic modelling to reveal relevant physical and chemical descriptors including segregation energies, existence and strength of atomic-scale diffusion barriers, surface energies and sub-surface chemical species identification. These approaches promise to provide tremendous insights from atomically resolved functional imaging, can provide relevant thermodynamic parameters, and auger well for use with first-principles calculations to yield quantitative atomic-level chemical identification and structure-property relations. This research was sponsored by the Division of Materials Sciences and Engineering, BES, DOE. Research was conducted at the Center for Nanophase Materials Sciences, which also provided support and is a DOE Office of Science User Facility.

  15. Current Trends in Atomic Spectroscopy.

    ERIC Educational Resources Information Center

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  16. Current Trends in Atomic Spectroscopy.

    ERIC Educational Resources Information Center

    Wynne, James J.

    1983-01-01

    Atomic spectroscopy is the study of atoms/ions through their interaction with electromagnetic radiation, in particular, interactions in which radiation is absorbed or emitted with an internal rearrangement of the atom's electrons. Discusses nature of this field, its status and future, and how it is applied to other areas of physics. (JN)

  17. Redundant Functions for Nap1 and Chz1 in H2A.Z Deposition.

    PubMed

    Dronamraju, Raghuvar; Ramachandran, Srinivas; Jha, Deepak K; Adams, Alexander T; DiFiore, Julia V; Parra, Michael A; Dokholyan, Nikolay V; Strahl, Brian D

    2017-09-07

    H2A.Z is a histone H2A variant that contributes to transcriptional regulation, DNA damage response and limits heterochromatin spreading. In Saccharomyces cerevisiae, H2A.Z is deposited by the SWR-C complex, which relies on several histone chaperones including Nap1 and Chz1 to deliver H2A.Z-H2B dimers to SWR-C. However, the mechanisms by which Nap1 and Chz1 cooperate to bind H2A.Z and their contribution to H2A.Z deposition in chromatin is not well understood. Using structural modeling and molecular dynamics simulations, we identify a series of H2A.Z residues that form a chaperone-specific binding surface. Mutation of these residues revealed different surface requirements for Nap1 and Chz1 interaction with H2A.Z. Consistent with this result, we found that loss of Nap1 or Chz1 individually resulted in mild defects in H2A.Z deposition, but that deletion of both Nap1 and Chz1 resulted in a significant reduction of H2A.Z deposition at promoters and led to heterochromatin spreading. Together, our findings reveal unique H2A.Z surface dependences for Nap1 and Chz1 and a redundant role for these chaperones in H2A.Z deposition.

  18. Reviews Equipment: Vibration detector Equipment: SPARK Science Learning System PS-2008 Equipment: Pelton wheel water turbine Book: Atomic: The First War of Physics and the Secret History of the Atom Bomb 1939-49 Book: Outliers: The Story of Success Book: T-Minus: The Race to the Moon Equipment: Fridge Rover Equipment: Red Tide School Spectrophotometer Web Watch

    NASA Astrophysics Data System (ADS)

    2010-03-01

    WE RECOMMEND Vibration detector SEP equipment measures minor tremors in the classroom SPARK Science Learning System PS-2008 Datalogger is easy to use and has lots of added possibilities Atomic: The First War of Physics and the Secret History of the Atom Bomb 1939-49 Book is crammed with the latest on the atom bomb T-Minus: The Race to the Moon Graphic novel depicts the politics as well as the science Fridge Rover Toy car can teach magnetics and energy, and is great fun Red Tide School Spectrophotometer Professional standard equipment for the classroom WORTH A LOOK Pelton wheel water turbine Classroom-sized version of the classic has advantages Outliers: The Story of Success Study of why maths is unpopular is relevant to physics teaching WEB WATCH IOP webcasts are improving but are still not as impressive as Jodrell Bank's Chromoscope website

  19. Correlative STED and Atomic Force Microscopy on Live Astrocytes Reveals Plasticity of Cytoskeletal Structure and Membrane Physical Properties during Polarized Migration

    PubMed Central

    Curry, Nathan; Ghézali, Grégory; Kaminski Schierle, Gabriele S.; Rouach, Nathalie; Kaminski, Clemens F.

    2017-01-01

    The plasticity of the cytoskeleton architecture and membrane properties is important for the establishment of cell polarity, adhesion and migration. Here, we present a method which combines stimulated emission depletion (STED) super-resolution imaging and atomic force microscopy (AFM) to correlate cytoskeletal structural information with membrane physical properties in live astrocytes. Using STED compatible dyes for live cell imaging of the cytoskeleton, and simultaneously mapping the cell surface topology with AFM, we obtain unprecedented detail of highly organized networks of actin and microtubules in astrocytes. Combining mechanical data from AFM with optical imaging of actin and tubulin further reveals links between cytoskeleton organization and membrane properties. Using this methodology we illustrate that scratch-induced migration induces cytoskeleton remodeling. The latter is caused by a polarization of actin and microtubule elements within astroglial cell processes, which correlates strongly with changes in cell stiffness. The method opens new avenues for the dynamic probing of the membrane structural and functional plasticity of living brain cells. It is a powerful tool for providing new insights into mechanisms of cell structural remodeling during physiological or pathological processes, such as brain development or tumorigenesis. PMID:28469559

  20. Correlative STED and Atomic Force Microscopy on Live Astrocytes Reveals Plasticity of Cytoskeletal Structure and Membrane Physical Properties during Polarized Migration.

    PubMed

    Curry, Nathan; Ghézali, Grégory; Kaminski Schierle, Gabriele S; Rouach, Nathalie; Kaminski, Clemens F

    2017-01-01

    The plasticity of the cytoskeleton architecture and membrane properties is important for the establishment of cell polarity, adhesion and migration. Here, we present a method which combines stimulated emission depletion (STED) super-resolution imaging and atomic force microscopy (AFM) to correlate cytoskeletal structural information with membrane physical properties in live astrocytes. Using STED compatible dyes for live cell imaging of the cytoskeleton, and simultaneously mapping the cell surface topology with AFM, we obtain unprecedented detail of highly organized networks of actin and microtubules in astrocytes. Combining mechanical data from AFM with optical imaging of actin and tubulin further reveals links between cytoskeleton organization and membrane properties. Using this methodology we illustrate that scratch-induced migration induces cytoskeleton remodeling. The latter is caused by a polarization of actin and microtubule elements within astroglial cell processes, which correlates strongly with changes in cell stiffness. The method opens new avenues for the dynamic probing of the membrane structural and functional plasticity of living brain cells. It is a powerful tool for providing new insights into mechanisms of cell structural remodeling during physiological or pathological processes, such as brain development or tumorigenesis.

  1. Bioactive benzofuran derivatives: moracins A-Z in medicinal chemistry.

    PubMed

    Naik, Ravi; Harmalkar, Dipesh S; Xu, Xuezhen; Jang, Kyusic; Lee, Kyeong

    2015-01-27

    Benzofuran heterocycles are fundamental structural units in a variety of biologically active natural products as well as synthetic materials. Over the time, benzofuran derivatives have attracted many researchers due to the broad scope of their biological activity, which include anticancer, antimicrobial, immunomodulatory, antioxidant and anti-inflammatory properties. Egonol, homoegonol and moracin families are biologically active natural products containing benzofuran heterocycle as basic structural units. This paper focuses on the moracin family (moracin A to Z). Morus, a genus of flowering plants in the family Moraceae, comprises 10-16 species of deciduous trees commonly known as mulberries. The root bark, stem bark and leaves of Morus alba, M. lhou, Morus macroura are the main sources for arylbenzofuran derivatives including the moracins. A large volume of research has been carried out on moracins and their derivatives, which has shown the pharmacological importance of this benzofuran heterocyclic nucleus. In this mini-review, we attempt to highlight the importance of moracins, as they have been a major source for drug development. Herein, we also summarize the current state of the art concerning the synthesis and medicinal use of moracins A-Z.

  2. Structural Health Monitoring for a Z-Type Special Vehicle

    PubMed Central

    Yuan, Chaolin; Ren, Liang; Li, Hongnan

    2017-01-01

    Nowadays there exist various kinds of special vehicles designed for some purposes, which are different from regular vehicles in overall dimension and design. In that case, accidents such as overturning will lead to large economical loss and casualties. There are still no technical specifications to follow to ensure the safe operation and driving of these special vehicles. Owing to the poor efficiency of regular maintenance, it is more feasible and effective to apply real-time monitoring during the operation and driving process. In this paper, the fiber Bragg grating (FBG) sensors are used to monitor the safety of a z-type special vehicle. Based on the structural features and force distribution, a reasonable structural health monitoring (SHM) scheme is presented. Comparing the monitoring results with the finite element simulation results guarantees the accuracy and reliability of the monitoring results. Large amounts of data are collected during the operation and driving progress to evaluate the structural safety condition and provide reference for SHM systems developed for other special vehicles. PMID:28587161

  3. Histone variant H2A.Z.2 mediates proliferation and drug sensitivity of malignant melanoma

    PubMed Central

    Vardabasso, Chiara; Gaspar-Maia, Alexandre; Hasson, Dan; Pünzeler, Sebastian; Valle-Garcia, David; Straub, Tobias; Keilhauer, Eva C.; Strub, Thomas; Dong, Joanna; Panda, Taniya; Chung, Chi-Yeh; Yao, Jonathan L.; Singh, Rajendra; Segura, Miguel F.; Fontanals-Cirera, Barbara; Verma, Amit; Mann, Matthias; Hernando, Eva; Hake, Sandra B.; Bernstein, Emily

    2015-01-01

    SUMMARY Histone variants are emerging as key regulatory molecules in cancer. Here we report a novel role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. H2A.Z.2 is highly expressed in metastatic melanoma, correlates with decreased patient survival, and is required for cellular proliferation. Our integrated genomic analyses reveal that H2A.Z.2 controls the transcriptional output of E2F target genes in melanoma cells. These genes are highly expressed and display a distinct signature of H2A.Z occupancy. We identify BRD2 as an H2A.Z interacting protein, whose levels are also elevated in melanoma. We further demonstrate that H2A.Z.2 regulated genes are bound by BRD2 and E2F1 in a H2A.Z.2-dependent manner. Importantly, H2A.Z.2 deficiency sensitizes melanoma cells to chemotherapy and targeted therapies. Collectively, our findings implicate H2A.Z.2 as a mediator of cell proliferation and drug sensitivity in malignant melanoma, holding translational potential for novel therapeutic strategies. PMID:26051178

  4. H2A.Z nucleosomes enriched over active genes are homotypic.

    PubMed

    Weber, Christopher M; Henikoff, Jorja G; Henikoff, Steven

    2010-12-01

    Nucleosomes that contain the histone variant H2A.Z are enriched around transcriptional start sites, but the mechanistic basis for this enrichment is unknown. A single octameric nucleosome can contain two H2A.Z histones (homotypic) or one H2A.Z and one canonical H2A (heterotypic). To elucidate the function of H2A.Z, we generated high-resolution maps of homotypic and heterotypic Drosophila H2A.Z (H2Av) nucleosomes. Although homotypic and heterotypic H2A.Z nucleosomes mapped throughout most of the genome, homotypic nucleosomes were enriched and heterotypic nucleosomes were depleted downstream of active promoters and intron-exon junctions. The distribution of homotypic H2A.Z nucleosomes resembled that of classical active chromatin and showed evidence of disruption during transcriptional elongation. Both homotypic H2A.Z nucleosomes and classical active chromatin were depleted downstream of paused polymerases. Our results suggest that H2A.Z enrichment patterns result from intrinsic structural differences between heterotypic and homotypic H2A.Z nucleosomes that follow disruption during transcriptional elongation.

  5. Constitutive turnover of histone H2A.Z at yeast promoters requires the preinitiation complex

    PubMed Central

    Tramantano, Michael; Sun, Lu; Au, Christy; Labuz, Daniel; Liu, Zhimin; Chou, Mindy; Shen, Chen; Luk, Ed

    2016-01-01

    The assembly of the preinitiation complex (PIC) occurs upstream of the +1 nucleosome which, in yeast, obstructs the transcription start site and is frequently assembled with the histone variant H2A.Z. To understand the contribution of the transcription machinery in the disassembly of the +1 H2A.Z nucleosome, conditional mutants were used to block PIC assembly. A quantitative ChIP-seq approach, which allows detection of global occupancy change, was employed to measure H2A.Z occupancy. Blocking PIC assembly resulted in promoter-specific H2A.Z accumulation, indicating that the PIC is required to evict H2A.Z. By contrast, H2A.Z eviction was unaffected upon depletion of INO80, a remodeler previously reported to displace nucleosomal H2A.Z. Robust PIC-dependent H2A.Z eviction was observed at active and infrequently transcribed genes, indicating that constitutive H2A.Z turnover is a general phenomenon. Finally, sites with strong H2A.Z turnover precisely mark transcript starts, providing a new metric for identifying cryptic and alternative sites of initiation. DOI: http://dx.doi.org/10.7554/eLife.14243.001 PMID:27438412

  6. Atomic and molecular theory

    SciTech Connect

    Inokuti, Mitio.

    1990-01-01

    The multifaceted role of theoretical physics in understanding the earliest stages of radiation action is discussed. Scientific topics chosen for the present discourse include photoabsorption, electron collisions, and ionic collisions, and electron transport theory, Connections of atomic and molecular physics with condensed-matter physics are also discussed. The present article includes some historical perspective and an outlook for the future. 114 refs., 3 figs.

  7. Shock waves in a Z-pinch and the formation of high energy density plasma

    SciTech Connect

    Rahman, H. U.; Wessel, F. J.; Ney, P.; Presura, R.; Ellahi, Rahmat; Shukla, P. K.

    2012-12-15

    A Z-pinch liner, imploding onto a target plasma, evolves in a step-wise manner, producing a stable, magneto-inertial, high-energy-density plasma compression. The typical configuration is a cylindrical, high-atomic-number liner imploding onto a low-atomic-number target. The parameters for a terawatt-class machine (e.g., Zebra at the University of Nevada, Reno, Nevada Terawatt Facility) have been simulated. The 2-1/2 D MHD code, MACH2, was used to study this configuration. The requirements are for an initial radius of a few mm for stable implosion; the material densities properly distributed, so that the target is effectively heated initially by shock heating and finally by adiabatic compression; and the liner's thickness adjusted to promote radial current transport and subsequent current amplification in the target. Since the shock velocity is smaller in the liner, than in the target, a stable-shock forms at the interface, allowing the central load to accelerate magnetically and inertially, producing a magneto-inertial implosion and high-energy density plasma. Comparing the implosion dynamics of a low-Z target with those of a high-Z target demonstrates the role of shock waves in terms of compression and heating. In the case of a high-Z target, the shock wave does not play a significant heating role. The shock waves carry current and transport the magnetic field, producing a high density on-axis, at relatively low temperature. Whereas, in the case of a low-Z target, the fast moving shock wave preheats the target during the initial implosion phase, and the later adiabatic compression further heats the target to very high energy density. As a result, the compression ratio required for heating the low-Z plasma to very high energy densities is greatly reduced.

  8. Atomic and Molecular Physics Program

    DTIC Science & Technology

    2012-03-07

    i i å Sz i +1 -hzSz i -hxSx i hx =0: classical first order phase transition Finite hx: quantum phase transition, second order 13...transition H = J i å Sz iSz i +1 - (1- D) Sz i - 23/2 t Sx i D = E-U E: energy difference per lattice site, or lattice tilt U: onsite interaction...distribution is unlimited. Laser cooling Dysprosium \\.J ••• • ·=--·-Rtnes • Ce ., Til Periodic Table of the Elements [iO " I

  9. The role of a detailed configuration accounting (DCA) atomic physics package in explaining the energy balance in ignition-scale hohlraums

    NASA Astrophysics Data System (ADS)

    Rosen, M. D.; Scott, H. A.; Hinkel, D. E.; Williams, E. A.; Callahan, D. A.; Town, R. P. J.; Divol, L.; Michel, P. A.; Kruer, W. L.; Suter, L. J.; London, R. A.; Harte, J. A.; Zimmerman, G. B.

    2011-09-01

    In 2009 the National Ignition Campaign (NIC) gas-filled/capsule-imploding hohlraum energetics campaign showed good laser-hohlraum coupling, reasonably high drive, and implosion symmetry control via cross-beam transfer. There were, however, discrepancies with expectations from the standard simulation model including: the level and spectrum of the Stimulated Raman light; the tendency towards pancake-shaped implosions; and drive that exceeded predictions early in the campaign, and lagged those predictions late in the campaign. We review here the origins/development path of the "high flux model" (HFM). The HFM contains two principal changes from the standard model: 1) It uses a detailed configuration accounting (DCA) atomic physics non-local-thermodynamic-equilibrium (NLTE) model, and 2) It uses a generous electron thermal flux limiter, f = 0.15, that is consistent with a non-local electron transport model. Both elements make important contributions to the HFM's prediction of a hohlraum plasma that is cooler than that predicted by the standard model, which uses an NLTE average atom approach, and a value of f = 0.05 for the flux limiter. This cooler plasma is key in eliminating most of the discrepancies between the NIC data and revised expectations based on this new simulation model. The HFM had previously been successfully deployed in correctly modeling Omega Laser illuminated gold sphere x-ray emission data, and NIC empty hohlraum drive. However, when the HFM was first applied to this energetics campaign, the model lacked some credibility/acceptance compared to the standard model, because it actually worsened the discrepancy between the observed hohlraum drive for the 1 MJ class experiments performed late in the campaign and the revised expectation of higher drive based on the HFM. Essentially, the HFM was making a prediction that the laser-hohlraum coupling was less than that assumed at that time. Its credibility was then boosted when a re-evaluation of the laser

  10. Reorganization of Damaged Chromatin by the Exchange of Histone Variant H2A.Z-2

    SciTech Connect

    Nishibuchi, Ikuno; Suzuki, Hidekazu; Kinomura, Aiko; Sun, Jiying; Liu, Ning-Ang; Horikoshi, Yasunori; Shima, Hiroki; Kusakabe, Masayuki; Harata, Masahiko; Fukagawa, Tatsuo; Ikura, Tsuyoshi; Ishida, Takafumi; Nagata, Yasushi; Tashiro, Satoshi

    2014-07-15

    Purpose: The reorganization of damaged chromatin plays an important role in the regulation of the DNA damage response. A recent study revealed the presence of 2 vertebrate H2A.Z isoforms, H2A.Z-1 and H2A.Z-2. However, the roles of the vertebrate H2A.Z isoforms are still unclear. Thus, in this study we examined the roles of the vertebrate H2A.Z isoforms in chromatin reorganization after the induction of DNA double-strand breaks (DSBs). Methods and Materials: To examine the dynamics of H2A.Z isoforms at damaged sites, we constructed GM0637 cells stably expressing each of the green fluorescent protein (GFP)-labeled H2A.Z isoforms, and performed fluorescence recovery after photobleaching (FRAP) analysis and inverted FRAP analysis in combination with microirradiation. Immunofluorescence staining using an anti-RAD51 antibody was performed to study the kinetics of RAD51 foci formation after 2-Gy irradiation of wild-type (WT), H2A.Z-1- and H2A.Z-2-deficient DT40 cells. Colony-forming assays were also performed to compare the survival rates of WT, H2A.Z-1-, and H2A.Z-2-deficient DT40 cells with control, and H2A.Z-1- and H2A.Z-2-depleted U2OS cells after irradiation. Results: FRAP analysis revealed that H2A.Z-2 was incorporated into damaged chromatin just after the induction of DSBs, whereas H2A.Z-1 remained essentially unchanged. Inverted FRAP analysis showed that H2A.Z-2 was released from damaged chromatin. These findings indicated that H2A.Z-2 was exchanged at DSB sites immediately after the induction of DSBs. RAD51 focus formation after ionizing irradiation was disturbed in H2A.Z-2-deficient DT40 cells but not in H2A.Z-1-deficient cells. The survival rate of H2A.Z-2-deficient cells after irradiation was lower than those of WT and H2A.Z-1- DT40 cells. Similar to DT40 cells, H2A.Z-2-depleted U2OS cells were also radiation-sensitive compared to control and H2A.Z-1-depleted cells. Conclusions: We found that vertebrate H2A.Z-2 is involved in the regulation of the DNA

  11. Atomic and molecular supernovae

    NASA Technical Reports Server (NTRS)

    Liu, Weihong

    1997-01-01

    Atomic and molecular physics of supernovae is discussed with an emphasis on the importance of detailed treatments of the critical atomic and molecular processes with the best available atomic and molecular data. The observations of molecules in SN 1987A are interpreted through a combination of spectral and chemical modelings, leading to strong constraints on the mixing and nucleosynthesis of the supernova. The non-equilibrium chemistry is used to argue that carbon dust can form in the oxygen-rich clumps where the efficient molecular cooling makes the nucleation of dust grains possible. For Type Ia supernovae, the analyses of their nebular spectra lead to strong constraints on the supernova explosion models.

  12. Toward Comprehensive Physical/Chemical Understanding of the Circumstellar Environments - Simultaneous Probing of Each of the Ionized/Atomic/Molecular Gas and Dust Components

    NASA Astrophysics Data System (ADS)

    Ueta, Toshiya

    also suggest that the central star of about 1.5 M_sun initial mass is terminating its PN evolution onto the white dwarf cooling track. The most notable aspect of the HerPlaNS analysis is simultaneous probing of each of the ionized/atomic/molecular gas and dust components in the target PN, which can properly determine relative abundances of these components as a function of position in the shell, allowing us to investigate the mass loss history. With this NASA ADAP proposal, we request funding to continue the simultaneous probing of all the PN components for the rest of 10 HerPlaNS target PNs and 13 other PNs in the Herschel Science Archive for which a full complement of the analysis can be performed (plus the remaining 29 PNs in the archive for which partial analysis is possible, for the sake of completeness). Our goals are to perform (1) broadband thermal dust emission fitting to establish the dust mass distribution in the target PNs and (2) farIR line diagnostics to establish the mass distribution of each of the ionized, atomic, and molecular gas components in the target PNs, so that we can create empirically-sound gasto-dust mass ratio maps which permit us to investigate the possibility of time variations in the gas-to-dust mass ratio over the course of mass loss history. We will also perform photoionization modeling using (py)CLOUDY and MOCASSIN to establish 3-D physical/chemical stratification within the nebulae as a manifestation of mass-loss modulations over the course of mass loss history. Our analysis is also assisted by optical data obtained through slit-scan mapping at the Gemini-North and South as well as the Subaru Telescope that are presently on-going (plus, spectral mapping with the Hubble Space Telescope and IFU observations at VLT, pending approval). Together with the farIR data, we can iteratively bootstrap line diagnostics so that we can determine the (Te, ne) profiles completely self-consistently without any prior assumptions.

  13. A difference in using atomic layer deposition or physical vapour deposition TiN as electrode material in metal-insulator-metal and metal-insulator-silicon capacitors.

    PubMed

    Groenland, A W; Wolters, R A M; Kovalgin, A Y; Schmitz, J

    2011-09-01

    In this work, metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) capacitors are studied using titanium nitride (TiN) as the electrode material. The effect of structural defects on the electrical properties on MIS and MIM capacitors is studied for various electrode configurations. In the MIM capacitors the bottom electrode is a patterned 100 nm TiN layer (called BE type 1), deposited via sputtering, while MIS capacitors have a flat bottom electrode (called BE type 2-silicon substrate). A high quality 50-100 nm thick SiO2 layer, made by inductively-coupled plasma CVD at 150 degrees C, is deposited as a dielectric on top of both types of bottom electrodes. BE type 1 (MIM) capacitors have a varying from low to high concentration of structural defects in the SiO2 layer. BE type 2 (MIS) capacitors have a low concentration of structural defects and are used as a reference. Two sets of each capacitor design are fabricated with the TiN top electrode deposited either via physical vapour deposition (PVD, i.e., sputtering) or atomic layer deposition (ALD). The MIM and MIS capacitors are electrically characterized in terms of the leakage current at an electric field of 0.1 MV/cm (I leak) and for different structural defect concentrations. It is shown that the structural defects only show up in the electrical characteristics of BE type 1 capacitors with an ALD TiN-based top electrode. This is due to the excellent step coverage of the ALD process. This work clearly demonstrates the sensitivity to process-induced structural defects, when ALD is used as a step in process integration of conductors on insulation materials.

  14. L. V. Keldysh's "Ionization in the Field of a Strong Electromagnetic Wave" and modern physics of atomic interaction with a strong laser field

    NASA Astrophysics Data System (ADS)

    Fedorov, M. V.

    2016-03-01

    Basic premises, approximations, and results of L.V. Keldysh's 1964 work on multiphoton ionization of atoms are discussed, as well as its influence on the modern science of the interaction of atomic-molecular systems with a strong laser field.

  15. Search for a $Z(4430)^{\\pm} \\to \\psi(2S)\\pi^{\\pm}$ resonance in hadron collisions at CDF II

    SciTech Connect

    Rubbo, Francesco

    2010-01-01

    The work described in this thesis is the first search for a Z-(4430) resonance in hadron collisions and has been conceived, carried out and concluded entirely by the author. An ad-hoc analysis framework has been developed based on reconstruction code already consolidated in other analysis, adapted and modified for the purpose of this work. The progress of the work has been periodically presented in internal meetings of the CDF B-physics group and documented in internal notes.

  16. Reviews Opera: Doctor Atomic DVD: Doctor Atomic Equipment: Digital stopclock with external trigger Book: I Cyborg Book: Flat Earth: The History of an Infamous Idea Book: Mere Thermodynamics Book: CGP revision guides Book: Hiding the Elephant: How Magicians Invented the Impossible Book: Back of the Envelope Physics Web Watch

    NASA Astrophysics Data System (ADS)

    2009-07-01

    WE RECOMMEND Doctor Atomic The new Doctor Atomic opera provkes discussion on ethics I Cyborg The world's first human cyborg shares his life story in I Cyborg Flat Earth: The History of an Infamous Idea Flat Earth gives us a different perspective on creationism Mere Thermodynamics An introductory text on the three laws CGP revision guides This revision guide suits all courses and every pocket Hiding the Elephant: How Magicians Invented the Impossible The mystery of many illusions are solved in this book Back of the Envelope Physics This reference deserves a place on your bookshelf WORTH A LOOK Doctor Atomic The DVD doesn't do justice to the live performance Digital stopclock with external trigger Use these stopclocks when you need an external trigger WEB WATCH Webcasts reach out to an online audience

  17. Deposition of Histone Variant H2A.Z within Gene Bodies Regulates Responsive Genes

    PubMed Central

    Coleman-Derr, Devin; Zilberman, Daniel

    2012-01-01

    The regulation of eukaryotic chromatin relies on interactions between many epigenetic factors, including histone modifications, DNA methylation, and the incorporation of histone variants. H2A.Z, one of the most conserved but enigmatic histone variants that is enriched at the transcriptional start sites of genes, has been implicated in a variety of chromosomal processes. Recently, we reported a genome-wide anticorrelation between H2A.Z and DNA methylation, an epigenetic hallmark of heterochromatin that has also been found in the bodies of active genes in plants and animals. Here, we investigate the basis of this anticorrelation using a novel h2a.z loss-of-function line in Arabidopsis thaliana. Through genome-wide bisulfite sequencing, we demonstrate that loss of H2A.Z in Arabidopsis has only a minor effect on the level or profile of DNA methylation in genes, and we propose that the global anticorrelation between DNA methylation and H2A.Z is primarily caused by the exclusion of H2A.Z from methylated DNA. RNA sequencing and genomic mapping of H2A.Z show that H2A.Z enrichment across gene bodies, rather than at the TSS, is correlated with lower transcription levels and higher measures of gene responsiveness. Loss of H2A.Z causes misregulation of many genes that are disproportionately associated with response to environmental and developmental stimuli. We propose that H2A.Z deposition in gene bodies promotes variability in levels and patterns of gene expression, and that a major function of genic DNA methylation is to exclude H2A.Z from constitutively expressed genes. PMID:23071449

  18. Tau physics

    SciTech Connect

    Perl, M.L.

    1993-03-01

    This report discusses the following topics: [tau] production and related [tau] properties; general discussion of [tau] decays; leptonic decays; hadronic decays; the [tau] in atomic physics; and the [tau] neutrino: [nu][sub [tau

  19. Tau physics

    SciTech Connect

    Perl, M.L.

    1993-03-01

    This report discusses the following topics: {tau} production and related {tau} properties; general discussion of {tau} decays; leptonic decays; hadronic decays; the {tau} in atomic physics; and the {tau} neutrino: {nu}{sub {tau}}

  20. Hypersymmetry: A Z{sub 3}-graded generalization of supersymmetry

    SciTech Connect

    Abramov, V.; Kerner, R.; Le Roy, B.

    1997-03-01

    We propose a generalization of non-commutative geometry and gauge theories based on ternary Z{sub 3}-graded structures. In the new algebraic structures we define, all products of two entities are left free, the only constraining relations being imposed on ternary products. These relations reflect the action of the Z{sub 3}-group, which may be either trivial, i.e., abc=bca=cab, generalizing the usual commutativity, or non-trivial, i.e., abc=jbca, with j=e{sup (2{pi}i)/3}. The usual Z{sub 2}-graded structures such as Grassmann, Lie, and Clifford algebras are generalized to the Z{sub 3}-graded case. Certain suggestions concerning the eventual use of these new structures in physics of elementary particles and fields are exposed. {copyright} {ital 1997 American Institute of Physics.}

  1. The histone variant H2A.Z is an important regulator of enhancer activity

    PubMed Central

    Brunelle, Mylène; Nordell Markovits, Alexei; Rodrigue, Sébastien; Lupien, Mathieu; Jacques, Pierre-Étienne; Gévry, Nicolas

    2015-01-01

    Gene regulatory programs in different cell types are largely defined through cell-specific enhancers activity. The histone variant H2A.Z has been shown to play important roles in transcription mainly by controlling proximal promoters, but its effect on enhancer functions remains unclear. Here, we demonstrate by genome-wide approaches that H2A.Z is present at a subset of active enhancers bound by the estrogen receptor alpha (ERα). We also determine that H2A.Z does not influence the local nucleosome positioning around ERα enhancers using ChIP sequencing at nucleosomal resolution and unsupervised pattern discovery. We further highlight that H2A.Z-enriched enhancers are associated with chromatin accessibility, H3K122ac enrichment and hypomethylated DNA. Moreover, upon estrogen stimulation, the enhancers occupied by H2A.Z produce enhancer RNAs (eRNAs), and recruit RNA polymerase II as well as RAD21, a member of the cohesin complex involved in chromatin interactions between enhancers and promoters. Importantly, their recruitment and eRNAs production are abolished by H2A.Z depletion, thereby revealing a novel functional link between H2A.Z occupancy and enhancer activity. Taken together, our findings suggest that H2A.Z acts as an important player for enhancer functions by establishing and maintaining a chromatin environment required for RNA polymerase II recruitment, eRNAs transcription and enhancer-promoters interactions, all essential attributes of enhancer activity. PMID:26319018

  2. Histone H2A.Z and DNA methylation are mutually antagonistic chromatin marks.

    PubMed

    Zilberman, Daniel; Coleman-Derr, Devin; Ballinger, Tracy; Henikoff, Steven

    2008-11-06

    Eukaryotic chromatin is separated into functional domains differentiated by post-translational histone modifications, histone variants and DNA methylation. Methylation is associated with repression of transcriptional initiation in plants and animals, and is frequently found in transposable elements. Proper methylation patterns are crucial for eukaryotic development, and aberrant methylation-induced silencing of tumour suppressor genes is a common feature of human cancer. In contrast to methylation, the histone variant H2A.Z is preferentially deposited by the Swr1 ATPase complex near 5' ends of genes where it promotes transcriptional competence. How DNA methylation and H2A.Z influence transcription remains largely unknown. Here we show that in the plant Arabidopsis thaliana regions of DNA methylation are quantitatively deficient in H2A.Z. Exclusion of H2A.Z is seen at sites of DNA methylation in the bodies of actively transcribed genes and in methylated transposons. Mutation of the MET1 DNA methyltransferase, which causes both losses and gains of DNA methylation, engenders opposite changes (gains and losses) in H2A.Z deposition, whereas mutation of the PIE1 subunit of the Swr1 complex that deposits H2A.Z leads to genome-wide hypermethylation. Our findings indicate that DNA methylation can influence chromatin structure and effect gene silencing by excluding H2A.Z, and that H2A.Z protects genes from DNA methylation.

  3. The histone variant H2A.Z promotes efficient cotranscriptional splicing in S. cerevisiae.

    PubMed

    Neves, Lauren T; Douglass, Stephen; Spreafico, Roberto; Venkataramanan, Srivats; Kress, Tracy L; Johnson, Tracy L

    2017-04-01

    In eukaryotes, a dynamic ribonucleic protein machine known as the spliceosome catalyzes the removal of introns from premessenger RNA (pre-mRNA). Recent studies show the processes of RNA synthesis and RNA processing to be spatio-temporally coordinated, indicating that RNA splicing takes place in the context of chromatin. H2A.Z is a highly conserved histone variant of the canonical histone H2A. In Saccharomyces cerevisiae, H2A.Z is deposited into chromatin by the SWR-C complex, is found near the 5' ends of protein-coding genes, and has been implicated in transcription regulation. Here we show that splicing of intron-containing genes in cells lacking H2A.Z is impaired, particularly under suboptimal splicing conditions. Cells lacking H2A.Z are especially dependent on a functional U2 snRNP (small nuclear RNA [snRNA] plus associated proteins), as H2A.Z shows extensive genetic interactions with U2 snRNP-associated proteins, and RNA sequencing (RNA-seq) reveals that introns with nonconsensus branch points are particularly sensitive to H2A.Z loss. Consistently, H2A.Z promotes efficient spliceosomal rearrangements involving the U2 snRNP, as H2A.Z loss results in persistent U2 snRNP association and decreased recruitment of downstream snRNPs to nascent RNA. H2A.Z impairs transcription elongation, suggesting that spliceosome rearrangements are tied to H2A.Z's role in elongation. Depletion of disassembly factor Prp43 suppresses H2A.Z-mediated splice defects, indicating that, in the absence of H2A.Z, stalled spliceosomes are disassembled, and unspliced RNAs are released. Together, these data demonstrate that H2A.Z is required for efficient pre-mRNA splicing and indicate a role for H2A.Z in coordinating the kinetics of transcription elongation and splicing. © 2017 Neves et al.; Published by Cold Spring Harbor Laboratory Press.

  4. The DREAM complex promotes gene body H2A.Z for target repression

    PubMed Central

    Latorre, Isabel; Chesney, Michael A.; Garrigues, Jacob M.; Stempor, Przemyslaw; Appert, Alex; Francesconi, Mirko; Strome, Susan

    2015-01-01

    The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes, but its mechanism of action is poorly understood. Here we show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. Our results indicate that the DREAM complex facilitates high gene body HTZ-1/H2A.Z, which plays a role in target gene repression. PMID:25737279

  5. The DREAM complex promotes gene body H2A.Z for target repression.

    PubMed

    Latorre, Isabel; Chesney, Michael A; Garrigues, Jacob M; Stempor, Przemyslaw; Appert, Alex; Francesconi, Mirko; Strome, Susan; Ahringer, Julie

    2015-03-01

    The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes, but its mechanism of action is poorly understood. Here we show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. Our results indicate that the DREAM complex facilitates high gene body HTZ-1/H2A.Z, which plays a role in target gene repression. © 2015 Latorre et al.; Published by Cold Spring Harbor Laboratory Press.

  6. H2A.Z.2.2 is an alternatively spliced histone H2A.Z variant that causes severe nucleosome destabilization

    PubMed Central

    Bönisch, Clemens; Schneider, Katrin; Pünzeler, Sebastian; Wiedemann, Sonja M.; Bielmeier, Christina; Bocola, Marco; Eberl, H. Christian; Kuegel, Wolfgang; Neumann, Jürgen; Kremmer, Elisabeth; Leonhardt, Heinrich; Mann, Matthias; Michaelis, Jens; Schermelleh, Lothar; Hake, Sandra B.

    2012-01-01

    The histone variant H2A.Z has been implicated in many biological processes, such as gene regulation and genome stability. Here, we present the identification of H2A.Z.2.2 (Z.2.2), a novel alternatively spliced variant of histone H2A.Z and provide a comprehensive characterization of its expression and chromatin incorporation properties. Z.2.2 mRNA is found in all human cell lines and tissues with highest levels in brain. We show the proper splicing and in vivo existence of this variant protein in humans. Furthermore, we demonstrate the binding of Z.2.2 to H2A.Z-specific TIP60 and SRCAP chaperone complexes and its active replication-independent deposition into chromatin. Strikingly, various independent in vivo and in vitro analyses, such as biochemical fractionation, comparative FRAP studies of GFP-tagged H2A variants, size exclusion chromatography and single molecule FRET, in combination with in silico molecular dynamics simulations, consistently demonstrate that Z.2.2 causes major structural changes and significantly destabilizes nucleosomes. Analyses of deletion mutants and chimeric proteins pinpoint this property to its unique C-terminus. Our findings enrich the list of known human variants by an unusual protein belonging to the H2A.Z family that leads to the least stable nucleosome known to date. PMID:22467210

  7. Changes in H2A.Z occupancy and DNA methylation during B-cell lymphomagenesis

    PubMed Central

    Conerly, Melissa L.; Teves, Sheila S.; Diolaiti, Daniel; Ulrich, Michelle; Eisenman, Robert N.; Henikoff, Steven

    2010-01-01

    The histone variant H2A.Z has been implicated in the regulation of gene expression, and in plants antagonizes DNA methylation. Here, we ask whether a similar relationship exists in mammals, using a mouse B-cell lymphoma model, where chromatin states can be monitored during tumorigenesis. Using native chromatin immunoprecipitation with microarray hybridization (ChIP-chip), we found a progressive depletion of H2A.Z around transcriptional start sites (TSSs) during MYC-induced transformation of pre-B cells and, subsequently, during lymphomagenesis. In addition, we found that H2A.Z and DNA methylation are generally anticorrelated around TSSs in both wild-type and MYC-transformed cells, as expected for the opposite effects of these chromatin features on promoter competence. Depletion of H2A.Z over TSSs both in cells that are induced to proliferate and in cells that are developing into a tumor suggests that progressive loss of H2A.Z during tumorigenesis results from the advancing disease state. These changes were accompanied by increases in chromatin salt solubility. Surprisingly, ∼30% of all genes showed a redistribution of H2A.Z from around TSSs to bodies of active genes during the transition from MYC-transformed to tumor cells, with DNA methylation lost from gene bodies where H2A.Z levels increased. No such redistributions were observed during MYC-induced transformation of wild-type pre-B cells. The documented role of H2A.Z in regulating transcription suggests that 30% of genes have the potential to be aberrantly expressed during tumorigenesis. Our results imply that antagonism between H2A.Z deposition and DNA methylation is a conserved feature of eukaryotic genes, and that transcription-coupled H2A.Z changes may play a role in cancer initiation and progression. PMID:20709945

  8. Influence of atomic physics on EDGE2D-EIRENE simulations of JET divertor detachment with carbon and beryllium/tungsten plasma-facing components

    NASA Astrophysics Data System (ADS)

    Guillemaut, C.; Pitts, R. A.; Kukushkin, A. S.; Gunn, J. P.; Bucalossi, J.; Arnoux, G.; Belo, P.; Brezinsek, S.; Brix, M.; Corrigan, G.; Devaux, S.; Flanagan, J.; Groth, M.; Harting, D.; Huber, A.; Jachmich, S.; Kruezi, U.; Lehnen, M.; Marchetto, C.; Marsen, S.; Meigs, A. G.; Meyer, O.; Stamp, M.; Strachan, J. D.; Wiesen, S.; Wischmeier, M.; EFDA Contributors, JET

    2014-09-01

    The EDGE2D-EIRENE code is applied for simulation of divertor detachment during matched density ramp experiments in high triangularity, L-mode plasmas in both JET-Carbon (JET-C) and JET-ITER-Like Wall (JET-ILW). The code runs without drifts and includes either C or Be as impurity, but not W, assuming that the W targets have been coated with Be via main chamber migration. The simulations reproduce reasonably well the observed particle flux detachment as density is raised in both JET-C and JET-ILW experiments and can better match the experimental in-out divertor target power asymmetry if the heat flux entering the outer divertor is artificially set at around 2-3 times that entering the inner divertor. A careful comparison between different sets of atomic physics processes used in EIRENE shows that the detachment modelled by EDGE2D-EIRENE relies only on an increase of the particle sinks and not on a decrease of the ionization source. For the rollover and the beginning of the partially detached phase, the particle losses by perpendicular transport and the molecular activated recombination processes are mainly involved. For a deeper detachment with significant target ion flux reduction, volume recombination appears to be the main contributor. The elastic molecule-ion collisions are also important to provide good neutral confinement in the divertor and thus stabilize the simulations at low electron temperature (Te), when the sink terms are strong. Comparison between EDGE2D-EIRENE and SOLPS4.3 simulations of the density ramp in C shows similar detachment trends, but the importance of the elastic ion-molecule collisions is reduced in SOLPS4.3. Both codes suggest that any process capable of increasing the neutral confinement in the divertor should help to improve the modelling of the detachment. A further outcome of this work has been to demonstrate that key JET divertor diagnostic signals—Langmuir probe Te and bolometric tomographic reconstructions—are running beyond

  9. Optics and interferometry with atoms and molecules

    SciTech Connect

    Cronin, Alexander D.; Schmiedmayer, Joerg; Pritchard, David E.

    2009-07-15

    Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review the basic tools for coherent atom optics are described including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on atom chips. Scientific advances in a broad range of fields that have resulted from the application of atom interferometers are reviewed. These are grouped in three categories: (i) fundamental quantum science, (ii) precision metrology, and (iii) atomic and molecular physics. Although some experiments with Bose-Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e., phenomena where each single atom interferes with itself.

  10. Atoms in Astronomy.

    ERIC Educational Resources Information Center

    Blanchard, Paul A.

    This booklet is part of an American Astronomical Society curriculum project designed to provide teaching materials to teachers of secondary school chemistry, physics, and earth science. A Basic Topics section discusses atomic structure, emphasizing states of matter at high temperature and spectroscopic analysis of light from the stars. A section…

  11. Magnetohydrodynamic solution for a Z pinch showing the production of a hot spot

    SciTech Connect

    Maxon, S.; Hammer, J.H.; Eddleman, J.L.; Tabak, M.; Zimmerman, G.B.; Alley, W.E.; Estabrook, K.G.; Harte, J.A.; Nash, T.J.; Sanford, T.W.; De Groot, J.S.

    1996-05-01

    Two-dimensional LASNEX [National Technical Information Service Document No. DE 81026329 (Zimmerman, Report No. UCRL-74811, 1973)] calculations are made for a Z pinch on Saturn, the low-impedance, low-inductance electron accelerator at the Sandia National Laboratories [D. D. Bloomquist {ital et} {ital al}. {ital Proceedings} {ital of} {ital the} {ital Sixth} {ital IEEE} {ital Pulsed} {ital Power} {ital Conference}, Arlington, VA, edited by P. J. Turchi and B. H. Bernstein (Institute of Electronics and Electrical Engineers, New York, 1987), p. 310]. The experiment is characterized by a current of 6 MA with a tungsten wire load (4 mg) at 2 mm. Two-dimensional calculations show the evolution of the Rayleigh{endash}Taylor instability to the bubble and spike phase, causing high-density islands to form in the pinch opposite the bubbles. The two-dimensional energy flow causes a {open_quote}{open_quote}hot spot{close_quote}{close_quote} to evolve, which is shown to agree in its size and brightness with pinhole camera measurements. This is the first explicit calculation of a hot spot in two dimensions employing the full magnetohydrodynamic equations. {copyright} {ital 1996 American Institute of Physics.}

  12. Understanding the In-Situ Star Formation in a z=1.7 Cluster Core Galaxy

    NASA Astrophysics Data System (ADS)

    Webb, Tracy

    2014-10-01

    We have discovered a rare beast of a central galaxy within a z=1.7 rich galaxy cluster (estimated ~4x10^14 Msun), forming stars at a prodigious rate of 1200 Msun/yr. This system is infrared bright and its SED and the detection of PAHs at the cluster redshift, implies the IR luminosity is dominated by star formation. Such an extreme system has to date, only been confirmed in the z=0.6 Phoenix cluster (McDonald et al. 2012, 2013, 2014), whereas this object is observed at a much earlier and more active epoch of galaxy and cluster evolution. Here we propose deep HST imaging with WFC3 F160W/F105W to investigate the morphology of the BCG galaxy and its nearest neighbours. Our main goal is to understand the physical processes fuelling the intense starburst, be it a major merger or infalling gas from a cooling flow. We will also characterize the morphological properties (with color information) of the central BCG. These data will be the first of their kind at this redshift and will relate overall formation and evolution of the central galaxy massive parent halo at a cosmological epoch where these processes may begin to dominate.

  13. The histone variant H2A.Z promotes splicing of weak introns.

    PubMed

    Nissen, Kelly E; Homer, Christina M; Ryan, Colm J; Shales, Michael; Krogan, Nevan J; Patrick, Kristin L; Guthrie, Christine

    2017-04-01

    Multiple lines of evidence implicate chromatin in the regulation of premessenger RNA (pre-mRNA) splicing. However, the influence of chromatin factors on cotranscriptional splice site usage remains unclear. Here we investigated the function of the highly conserved histone variant H2A.Z in pre-mRNA splicing using the intron-rich model yeast Schizosaccharomyces pombe Using epistatic miniarray profiles (EMAPs) to survey the genetic interaction landscape of the Swr1 nucleosome remodeling complex, which deposits H2A.Z, we uncovered evidence for functional interactions with components of the spliceosome. In support of these genetic connections, splicing-specific microarrays show that H2A.Z and the Swr1 ATPase are required during temperature stress for the efficient splicing of a subset of introns. Notably, affected introns are enriched for H2A.Z occupancy and more likely to contain nonconsensus splice sites. To test the significance of the latter correlation, we mutated the splice sites in an affected intron to consensus and found that this suppressed the requirement for H2A.Z in splicing of that intron. These data suggest that H2A.Z occupancy promotes cotranscriptional splicing of suboptimal introns that may otherwise be discarded via proofreading ATPases. Consistent with this model, we show that overexpression of splicing ATPase Prp16 suppresses both the growth and splicing defects seen in the absence of H2A.Z. © 2017 Nissen et al.; Published by Cold Spring Harbor Laboratory Press.

  14. Atomic Calligraphy

    NASA Astrophysics Data System (ADS)

    Imboden, Matthias; Pardo, Flavio; Bolle, Cristian; Han, Han; Tareen, Ammar; Chang, Jackson; Christopher, Jason; Corman, Benjamin; Bishop, David

    2013-03-01

    Here we present a MEMS based method to fabricate devices with a small number of atoms. In standard semiconductor fabrication, a large amount of material is deposited, after which etching removes what is not wanted. This technique breaks down for structures that approach the single atom limit, as it is inconceivable to etch away all but one atom. What is needed is a bottom up method with single or near single atom precision. We demonstrate a MEMS device that enables nanometer position controlled deposition of gold atoms. A digitally driven plate is swept as a flux of gold atoms passes through an aperture. Appling voltages on four comb capacitors connected to the central plate by tethers enable nanometer lateral precision in the xy plane over 15x15 sq. microns. Typical MEMS structures have manufacturing resolutions on the order of a micron. Using a FIB it is possible to mill apertures as small as 10 nm in diameter. Assuming a low incident atomic flux, as well as an integrated MEMS based shutter with microsecond response time, it becomes possible to deposit single atoms. Due to their small size and low power consumption, such nano-printers can be mounted directly in a cryogenic system at ultrahigh vacuum to deposit clean quench condensed metallic structures.

  15. Atomic supersymmetry

    NASA Technical Reports Server (NTRS)

    Kostelecky, V. Alan

    1993-01-01

    Atomic supersymmetry is a quantum-mechanical supersymmetry connecting the properties of different atoms and ions. A short description of some established results in the subject are provided and a few recent developments are discussed including the extension to parabolic coordinates and the calculation of Stark maps using supersymmetry-based models.

  16. New Developments in Atom Interferometry

    DTIC Science & Technology

    1992-07-01

    interferometers can be applied to a number of experiments in fundamental physics: tests of quantum mechanics such as the Aharonov - Casher effect (6), measurement of...qualitatively new types of experiments involving inertial effects , studies of atomic and molecular properties, tests of basic quantum physics, and may ultimately...laser light as the beam splitters. Atom interferometers will make possible qualitatively new types of experiments involving inertial effects , studies of

  17. Atom-by-atom assembly of defect-free one-dimensional cold atom arrays

    NASA Astrophysics Data System (ADS)

    Endres, Manuel; Bernien, Hannes; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R.; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D.

    2016-11-01

    The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a platform for the deterministic preparation of regular one-dimensional arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of more than 50 atoms in less than 400 milliseconds. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach may enable controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.

  18. Atom-by-atom assembly of defect-free one-dimensional cold atom arrays.

    PubMed

    Endres, Manuel; Bernien, Hannes; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D

    2016-11-25

    The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a platform for the deterministic preparation of regular one-dimensional arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of more than 50 atoms in less than 400 milliseconds. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach may enable controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements. Copyright © 2016, American Association for the Advancement of Science.

  19. L. V. Keldysh’s “Ionization in the Field of a Strong Electromagnetic Wave” and modern physics of atomic interaction with a strong laser field

    SciTech Connect

    Fedorov, M. V.

    2016-03-15

    Basic premises, approximations, and results of L.V. Keldysh’s 1964 work on multiphoton ionization of atoms are discussed, as well as its influence on the modern science of the interaction of atomic–molecular systems with a strong laser field.

  20. NONLINEAR ATOM OPTICS

    SciTech Connect

    T. MILONNI; G. CSANAK; ET AL

    1999-07-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objectives were to explore theoretically various aspects of nonlinear atom optics effects in cold-atom waves and traps. During the project a major development occurred the observation, by as many as a dozen experimental groups, of Bose-Einstein condensation (BEC) in cold-atom traps. This stimulated us to focus our attention on those aspects of nonlinear atom optics relating to BEC, in addition to continuing our work on a nonequilibrium formalism for dealing with the interaction of an electromagnetic field with multi-level atomic systems, allowing for macroscopic coherence effects such as BEC. Studies of several problems in BEC physics have been completed or are near completion, including the suggested use of external electric fields to modify the nature of the interatomic interaction in cold-atom traps; properties of two-phase condensates; and molecular loss processes associated with BEC experiments involving a so-called Feshbach resonance.

  1. The Histone Chaperones FACT and Spt6 Restrict H2A.Z from Intragenic Locations

    PubMed Central

    Jeronimo, Célia; Watanabe, Shinya; Kaplan, Craig D.; Peterson, Craig L.; Robert, François

    2015-01-01

    SUMMARY H2A.Z is a highly conserved histone variant involved in several key nuclear processes. It is incorporated into promoters by SWR-C-related chromatin remodeling complexes, but whether it is also actively excluded from non-promoter regions is not clear. Here, we provide genomic and biochemical evidence that RNA polymerase II (RNAPII) elongation-associated histone chaperones FACT and Spt6 both contribute to restricting H2A.Z from intragenic regions. In the absence of FACT or Spt6, the lack of efficient nucleosome reassembly coupled to pervasive incorporation of H2A.Z by mislocalized SWR-C alters chromatin composition and contributes to cryptic initiation. Thus, chaperone-mediated H2A.Z confinement is crucial for restricting the chromatin signature of gene promoters, which otherwise may license or promote cryptic transcription. PMID:25959393

  2. Remediation System Evaluation, A-Z Automotive in West Milford, New Jersey

    EPA Pesticide Factsheets

    The A-Z Automotive site is a former gasoline retail outlet and automobile service station located on Union Valley Road between St. George Street and Lou Ann Boulevard in West Milford, Passaic County, New Jersey.

  3. Acting Atoms.

    ERIC Educational Resources Information Center

    Farin, Susan Archie

    1997-01-01

    Describes a fun game in which students act as electrons, protons, and neutrons. This activity is designed to help students develop a concrete understanding of the abstract concept of atomic structure. (DKM)

  4. Kinetic Atom.

    ERIC Educational Resources Information Center

    Wilson, David B.

    1981-01-01

    Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

  5. Acting Atoms.

    ERIC Educational Resources Information Center

    Farin, Susan Archie

    1997-01-01

    Describes a fun game in which students act as electrons, protons, and neutrons. This activity is designed to help students develop a concrete understanding of the abstract concept of atomic structure. (DKM)

  6. Kinetic Atom.

    ERIC Educational Resources Information Center

    Wilson, David B.

    1981-01-01

    Surveys the research of scientists like Joule, Kelvin, Maxwell, Clausius, and Boltzmann as it comments on the basic conceptual issues involved in the development of a more precise kinetic theory and the idea of a kinetic atom. (Author/SK)

  7. Physical conditions in the cool parts of prominences and spicules - The effects of model atom level truncation on the derived plasma parameters

    NASA Technical Reports Server (NTRS)

    Landman, D. A.

    1986-01-01

    The effects on calculated lower-level population densities of the truncation of Na and Sr(+) model atoms are determined in the context of the present spectral diagnostic scheme for solar prominences and spicules. It is shown that neglect of the upper atomic levels in Na, in particular, leads to overestimates in electron density and gas pressure by factors of about 2 and about 4, respectively, and to underestimates in the degree of hydrogen ionization and in the line-of-sight thickness of emitting material again by factors of about 2 and about 4, respectively. The implications of the revised emitting region extents, in particular, on the validity of the diagnostic method for these features are discussed.

  8. International Conference on Atomic Physics (12TH) Held at Ann Arbor, Michigan on July 29-August 2, 1990. Abstracts of Contributed Papers.

    DTIC Science & Technology

    1990-09-26

    the flux vanishes. The diffusion equation is justified when the thermalization by Wall collisions drives the atomic velocity distribution to...cavity collisions in which particles can either lose energy or annihilate for a distribution of initial o-Ps energies. We expect such a combination to...shell electrons and a target nucleus due to outer electrons. However, this FP assumption is almost justified in the case of collision system dealt

  9. International Conference on Atomic Physics: Abstracts of Contributed Papers (12th) Held in Ann Arbor, Michigan on 29 July-3 August 1990

    DTIC Science & Technology

    1990-09-26

    1935 Fock5 showed how to cast the momentum-space form of the Schrodinger integral equation into the equation for 0(4) hyperspherical harmonics. The...linear equations, which may be easily numerically integrated . By adopting the same techniques, based on the Heisenberg equations, equations are obtained...for the motion of each atom, which are then integrated in conjunction with the equations for the internal degrees of freedom. In the limit of no

  10. Atomic and molecular science with synchrotron radiation

    SciTech Connect

    Not Available

    1989-11-07

    This paper discusses the following topics: electron correlation in atoms; atomic innershell excitation and decay mechanisms; timing experiments; x-ray scattering; properties of ionized species; electronic properties of actinide atoms; total photon-interaction cross sections; and molecular physics. 66 refs. (LSP)

  11. Atomic research

    NASA Technical Reports Server (NTRS)

    Hadaway, James B.; Connatser, Robert; Cothren, Bobby; Johnson, R. B.

    1993-01-01

    Work performed by the University of Alabama in Huntsville's (UAH) Center for Applied Optics (CAO) entitled Atomic Research is documented. Atomic oxygen (AO) effects on materials have long been a critical concern in designing spacecraft to withstand exposure to the Low Earth Orbit (LEO) environment. The objective of this research effort was to provide technical expertise in the design of instrumentation and experimental techniques for analyzing materials exposed to atomic oxygen in accelerated testing at NASA/MSFC. Such testing was required to answer fundamental questions concerning Space Station Freedom (SSF) candidate materials and materials exposed to atomic oxygen aboard the Long-Duration Exposure Facility (LDEF). The primary UAH task was to provide technical design, review, and analysis to MSFC in the development of a state-of-the-art 5eV atomic oxygen beam facility required to simulate the RAM-induced low earth orbit (LEO) AO environment. This development was to be accomplished primarily at NASA/MSFC. In support of this task, contamination effects and ultraviolet (UV) simulation testing was also to be carried out using NASA/MSFC facilities. Any materials analysis of LDEF samples was to be accomplished at UAH.

  12. Atom chip gravimeter

    NASA Astrophysics Data System (ADS)

    Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

    2016-04-01

    Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

  13. Heavy-atom derivatization.

    PubMed

    Garman, Elspeth; Murray, James W

    2003-11-01

    Most of the standard methods of solving macromolecular structures involve producing a protein crystal that is derivatized by an anomalous scatterer or heavy atom (MIR, SIRAS, MAD, SAD etc.). The theoretical methodology which underpins the extraction of phase information from such derivatives is widely available in the literature. In addition, there are comprehensive sources of information on the chemistry of heavy-atom compounds and the ligands with which they are known to interact, as well as the Heavy Atom Databank accessible on the World Wide Web. This contribution therefore aims to provide some information on the less well documented practical problems of firstly deciding on an overall strategy for derivatization and secondly performing the physical manipulations involved in producing heavy-atom derivatives from native protein crystals and then cryocooling them. Ways to optimize the chances of isomorphous unit cells are suggested. Methods of determining whether or not the heavy atom is bound are outlined, including the powerful technique of PIXE (particle-induced X-ray emission).

  14. Relativistic Dirac-Fock atom properties for Z = 121 to Z = 138

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Kas, J. J.; Rehr, J. J.; Ermler, W. C.

    2017-03-01

    We present relativistic Dirac-Fock calculations of atomic properties for atomic numbers Z = 121- 138, extending a previous tabulation of Desclaux. The calculations assume a single LS ground state configuration and include a correction for finite nuclear size, with an approximation for the mean nuclear mass A(Z) based on the liquid-drop model.

  15. Physics News in 1983.

    ERIC Educational Resources Information Center

    Schewe, Phillip F., Ed.

    Information is provided on some of the interesting and newsworthy developments in physics and its related fields during 1983. Areas considered include: (1) acoustics; (2) astrophysics; (3) condensed matter physics; (4) crystallography; (5) physics education; (6) electron and atomic physics; (7) elementary particle physics; (8) fluid dynamics; (9)…

  16. Physics News in 1983.

    ERIC Educational Resources Information Center

    Schewe, Phillip F., Ed.

    Information is provided on some of the interesting and newsworthy developments in physics and its related fields during 1983. Areas considered include: (1) acoustics; (2) astrophysics; (3) condensed matter physics; (4) crystallography; (5) physics education; (6) electron and atomic physics; (7) elementary particle physics; (8) fluid dynamics; (9)…

  17. Physics Division annual review, April 1, 1988--March 31, 1989

    SciTech Connect

    Thayer, K.J.

    1989-08-01

    This document discusses the following main topics: Research at Atlas; Operation and Development of Atlas; Medium-Energy Nuclear Physics and Weak Interactions; Theoretical Nuclear Physics; Interactions of Fast Atomic and Molecular Ions with Solid and Gaseous Targets; Atomic Physics at Synchrotron Light Sources; Atomic Physics at Atlas and the ECR Source; Theoretical Atomic Physics; High-Resolution Laser-rf Spectroscopy of Atomic and Molecular Beams; and Fast Ion-Beam/Laser Studies of Atomic and Molecular Structure.

  18. ATOMIC AND MOLECULAR PHYSICS: Stabilization and Shift of Frequency in an External Cavity Diode Laser with Solenoid-Assisted Saturated Absorption

    NASA Astrophysics Data System (ADS)

    Han, Shun-Li; Cheng, Bing; Zhang, Jing-Fang; Xu, Yun-Fei; Wang, Zhao-Ying; Lin, Qiang

    2009-06-01

    A simple method to realize both stabilization and shift of the frequency in an external cavity diode laser (ECDL) is reported. Due to the Zeeman effect, the saturated absorption spectrum of Rb atoms in a magnetic field is shifted. This shift can be used to detune the frequency of the ECDL, which is locked to the saturated absorption spectrum. The frequency shift amount can be controlled by changing the magnetic field for a specific polarization state of the laser beam. The advantages of this tunable frequency lock include low laser power requirement, without additional power loss, cheapness, and so on.

  19. Series expansions for the incomplete Lipschitz-Hankel integralYe 0(a, z)

    NASA Astrophysics Data System (ADS)

    Mechaik, Mehdi M.; Dvorak, Steven L.

    1996-03-01

    Three series expansions are derived for the incomplete Lipschitz-Hankel integral YeO(a, z) for complex-valued a and z. Two novel expansions are obtained by using contour integration techniques to evaluate the inverse Laplace transform representation for YeO(a, z). A third expansion is obtained by replacing the Neumann function by its Neumann series representation and integrating the resulting terms. An algorithm is outlined which chooses the most efficient expansion for given values of a and z. Comparisons of numerical results for these series expansions with those obtained by using numerical integration routines show that the expansions are very efficient and yield accurate results even for values of a and z for which numerical integration fails to converge. The integral representations for YeO(a, z) obtained in this paper are combined with previously obtained integral representations for Jeo(a, z) to derive integral representations for HeO(1) (a, z) and HeO(2) (α, z). Recurrence relations can be used to efficiently compute higher-order incomplete Lipschitz-Hankel integrals and to find integral representations and series expansions for these special functions and many other related functions.

  20. Arabidopsis meiotic crossover hot spots overlap with H2A.Z nucleosomes at gene promoters.

    PubMed

    Choi, Kyuha; Zhao, Xiaohui; Kelly, Krystyna A; Venn, Oliver; Higgins, James D; Yelina, Nataliya E; Hardcastle, Thomas J; Ziolkowski, Piotr A; Copenhaver, Gregory P; Franklin, F Chris H; McVean, Gil; Henderson, Ian R

    2013-11-01

    PRDM9 directs human meiotic crossover hot spots to intergenic sequence motifs, whereas budding yeast hot spots overlap regions of low nucleosome density (LND) in gene promoters. To investigate hot spots in plants, which lack PRDM9, we used coalescent analysis of genetic variation in Arabidopsis thaliana. Crossovers increased toward gene promoters and terminators, and hot spots were associated with active chromatin modifications, including H2A.Z, histone H3 Lys4 trimethylation (H3K4me3), LND and low DNA methylation. Hot spot-enriched A-rich and CTT-repeat DNA motifs occurred upstream and downstream, respectively, of transcriptional start sites. Crossovers were asymmetric around promoters and were most frequent over CTT-repeat motifs and H2A.Z nucleosomes. Pollen typing, segregation and cytogenetic analysis showed decreased numbers of crossovers in the arp6 H2A.Z deposition mutant at multiple scales. During meiosis, H2A.Z forms overlapping chromosomal foci with the DMC1 and RAD51 recombinases. As arp6 reduced the number of DMC1 or RAD51 foci, H2A.Z may promote the formation or processing of meiotic DNA double-strand breaks. We propose that gene chromatin ancestrally designates hot spots within eukaryotes and PRDM9 is a derived state within vertebrates.

  1. Arabidopsis meiotic crossover hotspots overlap with H2A.Z nucleosomes at gene promoters

    PubMed Central

    Choi, Kyuha; Zhao, Xiaohui; Kelly, Krystyna A.; Venn, Oliver; Higgins, James D.; Yelina, Nataliya E.; Hardcastle, Thomas J.; Ziolkowski, Piotr A.; Copenhaver, Gregory P.; Franklin, F. Chris H.; McVean, Gil; Henderson, Ian R.

    2013-01-01

    PRDM9 directs human meiotic crossover hotspots to intergenic sequence motifs, whereas budding yeast hotspots overlap low nucleosome density regions in gene promoters. To investigate hotspots in plants, which lack PRDM9, we used coalescent analysis of Arabidopsis genetic variation. Crossovers increase towards gene promoters and terminators, and hotspots are associated with active chromatin modifications, including H2A.Z, histone H3K4me3, low nucleosome density and low DNA methylation. Hotspot-enriched A-rich and CTT-repeat DNA motifs occur upstream and downstream of transcriptional start respectively. Crossovers are asymmetric around promoters and highest over CTT-motifs and H2A.Z-nucleosomes. Pollen-typing, segregation and cytogenetic analysis show decreased crossovers in the arp6 H2A.Z deposition mutant, at multiple scales. During meiosis H2A.Z and DMC1/RAD51 recombinases form overlapping chromosomal foci. As arp6 reduces DMC1/RAD51 foci, H2A.Z may promote formation or processing of meiotic DNA double-strand breaks. We propose that gene chromatin ancestrally designates hotspots within eukaryotes and PRDM9 is a derived state within vertebrates. PMID:24056716

  2. Histone H2A.Z subunit exchange controls consolidation of recent and remote memory.

    PubMed

    Zovkic, Iva B; Paulukaitis, Brynna S; Day, Jeremy J; Etikala, Deepa M; Sweatt, J David

    2014-11-27

    Memory formation is a multi-stage process that initially requires cellular consolidation in the hippocampus, after which memories are downloaded to the cortex for maintenance, in a process termed systems consolidation. Epigenetic mechanisms regulate both types of consolidation, but histone variant exchange, in which canonical histones are replaced with their variant counterparts, is an entire branch of epigenetics that has received limited attention in the brain and has never, to our knowledge, been studied in relation to cognitive function. Here we show that histone H2A.Z, a variant of histone H2A, is actively exchanged in response to fear conditioning in the hippocampus and the cortex, where it mediates gene expression and restrains the formation of recent and remote memory. Our data provide evidence for H2A.Z involvement in cognitive function and specifically implicate H2A.Z as a negative regulator of hippocampal consolidation and systems consolidation, probably through downstream effects on gene expression. Moreover, alterations in H2A.Z binding at later stages of systems consolidation suggest that this histone has the capacity to mediate stable molecular modifications required for memory retention. Overall, our data introduce histone variant exchange as a novel mechanism contributing to the molecular basis of cognitive function and implicate H2A.Z as a potential therapeutic target for memory disorders.

  3. Transcriptional and post-transcriptional regulation of histone variant H2A.Z during sea urchin development.

    PubMed

    Hajdu, Mihai; Calle, Jasmine; Puno, Andrea; Haruna, Aminat; Arenas-Mena, César

    2016-12-01

    Histone variant H2A.Z promotes chromatin accessibility at transcriptional regulatory elements and is developmentally regulated in metazoans. We characterize the transcriptional and post-transcriptional regulation of H2A.Z in the purple sea urchin Strongylocentrotus purpuratus. H2A.Z depletion by antisense translation-blocking morpholino oligonucleotides during early development causes developmental collapse, in agreement with its previously demonstrated general role in transcriptional multipotency. During H2A.Z peak expression in 24-h embryos, endogenous H2A.Z 3' UTR sequences stabilize GFP mRNAs relative to those with SV40 3' UTR sequences, although the 3' UTR of H2A.Z does not determine the spatial distribution of H2A.Z transcripts during embryonic and postembryonic development. We elaborated an H2A.Z::GFP BAC reporter that reproduces embryonic H2A.Z expression. Genome-wide chromatin accessibility analysis using ATAC-seq revealed a cis-regulatory module (CRM) that, when deleted, causes a significant decline of the H2A.Z reporter expression. In addition, the mutation of a Sox transcription factor binding site motif and, more strongly, of a Myb motif cause significant decline of reporter gene expression. Our results suggest that an undetermined Myb-family transcription factor controls the transcriptional regulation of H2A.Z. © 2016 Japanese Society of Developmental Biologists.

  4. Davisson-Germer Prize in Atomic or Surface Physics Talk: Soft X-Ray Studies of Surfaces, Interfaces and Thin Films: From Spectroscopy to Ultrafast Nanoscale Movies

    NASA Astrophysics Data System (ADS)

    Stöhr, Joachim

    2011-03-01

    My talk will review the development of soft x-ray spectroscopy and microscopy and its impact on our understanding of chemical bonding, magnetism and dynamics at surfaces and interfaces. I will first outline important soft x-ray spectroscopy and microscopy techniques that have been developed over the last 30 years and their key strengths such as elemental and chemical specificity, sensitivity to small atomic concentrations, separation of charge and spin properties, spatial resolution down to the nanometer scale, and temporal resolution down to the intrinsic femtosecond timescale of atomic and electronic motions. I will then present scientific breakthroughs based on soft x-ray studies in three selected areas: the nature of molecular bonding and reactivity on metal surfaces, the molecular origin of liquid crystal alignment on surfaces, and the microscopic origin of interface-mediated spin alignments in modern magnetic devices. My talk will also cover the use of soft x-rays for revealing the temporal evolution of electronic structure, addressing the key problem of ``function,'' down to the intrinsic femtosecond time scale of charge and spin configuration changes. As examples I will present the formation and breaking of chemical bonds in surface complexes and the motion of the magnetization in magnetic devices. Work supported by the Office of Basic Energy Science of the US Department of Energy.

  5. Histone H2A.Z regulats transcription and is partially redundant with nucleosome remodeling complexes.

    PubMed

    Santisteban, M S; Kalashnikova, T; Smith, M M

    2000-10-27

    Nucleosomes impose a block to transcription that can be overcome in vivo by remodeling complexes such as SNF/SWI and histone modification complexes such as SAGA. Mutations in the major core histones relieve transcriptional repression and bypass the requirement for SNF/SWI and SAGA. We have found that the variant histone H2A.Z regulates gene transcription, and deletion of the gene encoding H2A.Z strongly increases the requirement for SNF/SWI and SAGA. This synthetic genetic interaction is seen at the level of single genes and acts downstream of promoter nucleosome reorganization. H2A.Z is preferentially crosslinked in vivo to intergenic DNA at the PH05 and GAL1 loci, and this association changes with transcriptional activation. These results describe a novel pathway for regulating transcription using variant histones to modulate chromatin structure.

  6. Physics: A Career for You?

    ERIC Educational Resources Information Center

    American Inst. of Physics, New York, NY.

    Information is provided for students who may be interested in pursuing a career in physics. This information includes the type of work done and areas studied by physicists in the following areas: nuclear physics, solid-state physics, elementary-particle physics, atomic/molecular/electron physics, fluid/plasma physics, space/planetary physics,…

  7. Physics in the Twentieth Century

    ERIC Educational Resources Information Center

    Weisskopf, Victor F.

    1970-01-01

    Provides a review of the great discoveries, theoretical concepts and development of physics in the 20th century. The growth and significance of diverse fields such as quantum theory, relativity theory, atomic physics, molecular physics, the physics of the solid state, nuclear physics, astrophysics, plasma physics, and particle physics are…

  8. Physics: A Career for You?

    ERIC Educational Resources Information Center

    American Inst. of Physics, New York, NY.

    Information is provided for students who may be interested in pursuing a career in physics. This information includes the type of work done and areas studied by physicists in the following areas: nuclear physics, solid-state physics, elementary-particle physics, atomic/molecular/electron physics, fluid/plasma physics, space/planetary physics,…

  9. Physics in the Twentieth Century

    ERIC Educational Resources Information Center

    Weisskopf, Victor F.

    1970-01-01

    Provides a review of the great discoveries, theoretical concepts and development of physics in the 20th century. The growth and significance of diverse fields such as quantum theory, relativity theory, atomic physics, molecular physics, the physics of the solid state, nuclear physics, astrophysics, plasma physics, and particle physics are…

  10. APPLICATIONS OF LASERS AND OTHER TOPICS IN LASER PHYSICS AND TECHNOLOGY: Investigation of the properties of resonance holograms in a beam of sodium atoms

    NASA Astrophysics Data System (ADS)

    Grigoriev, Igor'S.; Likhanskiĭ, V. V.; Semerok, A. F.; Firsov, Valerii A.; Chankin, A. V.

    1987-10-01

    Experimental and theoretical (using a two-level approximation) investigations were made of the properties of resonance holograms (excited-state gratings) created by monochromatic linearly polarized radiation from a cw dye laser in a beam of sodium atoms as a result of the 32P3/2- 32S1/2(F=2) transition. A good qualitative agreement was observed between the theory and experimental results. It was established that the maximum diffraction efficiency was attained when the intensity of the radiation used to form the hologram was of the order of the intensity needed to saturate the transition and the optical thickness of the beam was ~1.1. The sensitivity of the medium was ~1 nJ/cm2 for 1% diffraction efficiency.

  11. Physical composition

    NASA Astrophysics Data System (ADS)

    Healey, Richard

    2013-02-01

    Atomistic metaphysics motivated an explanatory strategy which science has pursued with great success since the scientific revolution. By decomposing matter into its atomic and subatomic parts physics gave us powerful explanations and accurate predictions as well as providing a unifying framework for the rest of science. The success of the decompositional strategy has encouraged a widespread conviction that the physical world forms a compositional hierarchy that physics and other sciences are progressively articulating. But this conviction does not stand up to a closer examination of how physics has treated composition, as a variety of case studies will show.

  12. Atomic, Molecular, and Optical Physics: Optical Excitation Function of H(1s-2p) Produced by electron Impact from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Bray, I.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1997-01-01

    The optical excitation function of prompt Lyman-Alpha radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet mono- chromator system was used to measure the emitted Lyman-Alpha radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Statistical and known systematic uncertainties in our data range from +/- 4% near threshold to +/- 2% at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close- coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10% level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7% of the CCC calculations over the 14 eV-1.8 keV range. The present CCC calculations converge on the Bethe- Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3% is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV - 1.8 keV energy range.

  13. Quantum Manybody Physics with Rydberg Polaritons

    DTIC Science & Technology

    2016-06-22

    physics , manybody physics , atomic physics , cold atoms , cavity QED, FPGA U U U UU Julia F. Stewart 973.656.9062 DISTRIBUTION A: Distribution approved...Neubauer Family Assistant Professor of Physics 929 East 57th Street GCIS E207 Chicago, Illinois 60637 773.702.9661 simonjon@uchicago.edu Atomic and...we have built a cold atom machine combining the challenges of Rydberg physics with the challenges of cavity quantum electrodynamics. The apparatus

  14. Atomic arias

    NASA Astrophysics Data System (ADS)

    Crease, Robert P.

    2009-01-01

    The American composer John Adams uses opera to dramatize controversial current events. His 1987 work Nixon in China was about the landmark meeting in 1972 between US President Richard Nixon and Chairman Mao Zedong of China; The Death of Klinghoffer (1991) was a musical re-enactment of an incident in 1985 when Palestinian terrorists kidnapped and murdered a wheelchair-bound Jewish tourist on a cruise ship. Adams's latest opera, Doctor Atomic, is also tied to a controversial event: the first atomic-bomb test in Alamogordo, New Mexico, on 16 June 1945. The opera premièred in San Francisco in 2005, had a highly publicized debut at the Metropolitan Opera in New York in 2008, and will have another debut on 25 February - with essentially the same cast - at the English National Opera in London.

  15. Atomic rivals

    SciTech Connect

    Goldschmidt, B.

    1990-01-01

    This book is a memoir of rivalries among the Allies over the bomb, by a participant and observer. Nuclear proliferation began in the uneasy wartime collaboration of the United States, England, Canada, and Free France to produce the atom bomb. Through the changes of history, a young French chemist had a role in almost every act of this international drama. This memoir is based on Goldschmidt's own recollections, interviews with other leading figures, and 3,000 pages of newly declassified documents in Allied archives. From his own start as Marie Curie's lab assistant, Goldschmidt's career was closely intertwined with Frances complicated rise to membership in the nuclear club. As a refugee from the Nazis, he became part of the wartime nuclear energy project in Canada and found himself the only French scientist to work (although briefly) on the American atom bomb project.

  16. DT ignition in a Z pinch compressed by an imploding liner

    NASA Astrophysics Data System (ADS)

    Bilbao, L.; Bernal, L.; Linhart, J. G.; Verri, G.

    2001-11-01

    It has been shown that an m = 0 instability of a Z pinch carrying a current of the order of 10 MA with a rise time of less than 10 ns can generate a spark capable of igniting a fusion detonation in the adjacent DT plasma channel. A possible method for generating such currents, necessary for the implosion of an initial large radius, low temperature Z pinch, can be a radial implosion of a cylindrical fast liner. The problem has been addressed in previous publications without considering the role played by an initially impressed m = 0 perturbation, a mechanism indispensable for the generation of a spark. The liner-Z pinch dynamics can be solved at several levels of physical model completeness. The first corresponds to a zero dimensional model in which the liner has a given mass per unit length and a zero thickness, the plasma is compressed adiabatically and is isotropic, and there are no energy losses or Joule heating. The second level is one dimensional. The Z pinch plasma is described by the full set of MHD, two-fluid equations. The liner is treated first as thin and incompressible, and subsequently it is assumed that it has a finite thickness and is composed of a heavy ion plasma, having an artificial but realistic equation of state. Both plasma and liner are considered uniform in the Z direction and only DT reactions are considered. It is shown that, given sufficient energy and speed of the liner, the Z pinch can reach a volume ignition. The third level is two dimensional. Plasma and liner are treated as in the second level but either the Z pinch or the liner is perturbed by an m = 0 non-uniformity. Provided the liner energy is high enough and the initial m = 0 perturbation is correctly chosen, the final neck plasma can act as a spark for DT ignition. It is also shown that the liner energy required for generating a spark and the subsequent detonation propagation are considerably less than in the case of volume ignition.

  17. A Physics Finale.

    ERIC Educational Resources Information Center

    Haynes, Gail E.

    1991-01-01

    A third-semester physics course that covers the topics of atomic physics, the theory of relativity, and nuclear energy is described. Activities that include the phenomenon of radioactivity, field trips to a nuclear power plant, a simulation of a chain reaction, and comparing the size of atomic particles are presented. (KR)

  18. A Physics Finale.

    ERIC Educational Resources Information Center

    Haynes, Gail E.

    1991-01-01

    A third-semester physics course that covers the topics of atomic physics, the theory of relativity, and nuclear energy is described. Activities that include the phenomenon of radioactivity, field trips to a nuclear power plant, a simulation of a chain reaction, and comparing the size of atomic particles are presented. (KR)

  19. The Search for the Higgs Boson and New Resonances Decaying to a Z Boson and a Photon

    NASA Astrophysics Data System (ADS)

    Pollack, Brian

    The Large Hadron Collider collected its first full sets of proton-proton collision data in 2011 and 2012. Using the Compact Muon Solenoid detector, two analyses were per- formed that searched for potential new physics with Z boson plus photon final states. The first analysis is a Higgs boson search, which looks for an enhancement of the recently discovered 125 GeV Higgs boson in the H → Zgamma → ℓℓgamma decay mode. The disintegration of the Higgs to a Z boson and a photon is expected to be at the per mil level, and any enhancement in this decay channel would be indirect evidence of new physics that would contribute to the loop diagrams responsible for the decay. The second analysis is a model independent search that looks for any potential A → Zgamma → ℓℓgamma signal, where A is any new resonance, in the mass range of 200 GeV or higher. The discovery of a signal in this channel would be direct evidence of physics beyond the standard model, and especially relevant for composite Higgs models that predict high sensitivity to the Zgamma decay mode. Both searches employ data driven background estimation methods and optimized event selection to maximum signal sensitivity. The results of the low mass Higgs boson search show agreement with the standard model of particle physics, with expected exclusion limits at about 10 times the standard model, and observed exclusion limits at about 9.5 times the standard model. The results of the A → Zgamma → ℓℓgamma search exclude the presence of this resonance and decay mode in excess of about 1 fb for 200 GeV and higher. The sensitivity of this channel is found to be stronger than all other diboson channels. These results place strong limits on new physics models, and will guide the next generation of searches at the LHC for Run 2.

  20. Detection of single atoms by resonance ionization spectroscopy

    SciTech Connect

    Hurst, G.S.

    1986-01-01

    Rutherford's idea for counting individual atoms can, in principle, be implemented for nearly any type of atom, whether stable or radioactive, by using methods of resonance ionization. With the RIS technique, a laser is tuned to a wavelength which will promote a valence electron in a Z-selected atom to an excited level. Additional resonance or nonresonance photoabsorption steps are used to achieve nearly 100% ionization efficiencies. Hence, the RIS process can be saturated for the Z-selected atoms; and since detectors are available for counting either single electrons or positive ions, one-atom detection is possible. Some examples are given of one-atom detection, including that of the noble gases, in order to show complementarity with AMS methods. For instance, the detection of /sup 81/Kr using RIS has interesting applications for solar neutrino research, ice-cap dating, and groundwater dating. 39 refs., 7 figs., 2 tabs.

  1. Histone Hypervariants H2A.Z.1 and H2A.Z.2 Play Independent and Context-Specific Roles in Neuronal Activity-Induced Transcription of Arc/Arg3.1 and Other Immediate Early Genes

    PubMed Central

    Dunn, Carissa J.; Sarkar, Pushpita; Bailey, Emma R.; Zhao, Meilan

    2017-01-01

    Abstract The histone variant H2A.Z is an essential and conserved regulator of eukaryotic gene transcription. However, the exact role of this histone in the transcriptional process remains perplexing. In vertebrates, H2A.Z has two hypervariants, H2A.Z.1 and H2A.Z.2, that have almost identical sequences except for three amino acid residues. Due to such similarity, functional specificity of these hypervariants in neurobiological processes, if any, remain largely unknown. In this study with dissociated rat cortical neurons, we asked if H2A.Z hypervariants have distinct functions in regulating basal and activity-induced gene transcription. Hypervariant-specific RNAi and microarray analyses revealed that H2A.Z.1 and H2A.Z.2 regulate basal expression of largely nonoverlapping gene sets, including genes that code for several synaptic proteins. In response to neuronal activity, rapid transcription of our model gene Arc is impaired by depletion of H2A.Z.2, but not H2A.Z.1. This impairment is partially rescued by codepletion of the H2A.Z chaperone, ANP32E. In contrast, under a different context (after 48 h of tetrodotoxin, TTX), rapid transcription of Arc is impaired by depletion of either hypervariant. Such context-dependent roles of H2A.Z hypervariants, as revealed by our multiplexed gene expression assays, are also evident with several other immediate early genes, where regulatory roles of these hypervariants vary from gene to gene under different conditions. Together, our data suggest that H2A.Z hypervariants have context-specific roles that complement each other to mediate activity-induced neuronal gene transcription. PMID:28856239

  2. Histone Hypervariants H2A.Z.1 and H2A.Z.2 Play Independent and Context-Specific Roles in Neuronal Activity-Induced Transcription of Arc/Arg3.1 and Other Immediate Early Genes.

    PubMed

    Dunn, Carissa J; Sarkar, Pushpita; Bailey, Emma R; Farris, Shannon; Zhao, Meilan; Ward, James M; Dudek, Serena M; Saha, Ramendra N

    2017-01-01

    The histone variant H2A.Z is an essential and conserved regulator of eukaryotic gene transcription. However, the exact role of this histone in the transcriptional process remains perplexing. In vertebrates, H2A.Z has two hypervariants, H2A.Z.1 and H2A.Z.2, that have almost identical sequences except for three amino acid residues. Due to such similarity, functional specificity of these hypervariants in neurobiological processes, if any, remain largely unknown. In this study with dissociated rat cortical neurons, we asked if H2A.Z hypervariants have distinct functions in regulating basal and activity-induced gene transcription. Hypervariant-specific RNAi and microarray analyses revealed that H2A.Z.1 and H2A.Z.2 regulate basal expression of largely nonoverlapping gene sets, including genes that code for several synaptic proteins. In response to neuronal activity, rapid transcription of our model gene Arc is impaired by depletion of H2A.Z.2, but not H2A.Z.1. This impairment is partially rescued by codepletion of the H2A.Z chaperone, ANP32E. In contrast, under a different context (after 48 h of tetrodotoxin, TTX), rapid transcription of Arc is impaired by depletion of either hypervariant. Such context-dependent roles of H2A.Z hypervariants, as revealed by our multiplexed gene expression assays, are also evident with several other immediate early genes, where regulatory roles of these hypervariants vary from gene to gene under different conditions. Together, our data suggest that H2A.Z hypervariants have context-specific roles that complement each other to mediate activity-induced neuronal gene transcription.

  3. Recent developments in atomizers for electrothermal atomic absorption spectrometry.

    PubMed

    Frech, W

    1996-06-01

    This review first describes general requirements to be met for suitable base materials used to produce electrothermal atomizers (ETAs). In this connection the physical and chemical properties of adequate types of graphite and metals are discussed. Further, various atomizer designs, their temperature dynamics during atomization and general performance characteristics are critically reviewed. For end-heated Massmann-type atomizers, discussions are focused on recent developments of, e.g., contoured tubes to achieve improved temperature homogeneity over the tube length, second surface atomizers to realize temporally isothermal atomization and tubes with graphite filters to reduce interference effects. The state-of-the-art of platform equipped, side-heated atomizers with integrated contacting bridges are characterized mainly with respect to heating dynamics, as well as susceptibility to interference- and memory effects. In contrast to end-heated ETAs, the tube ends of side-heated ETAs are freely located in the furnace compartment and, as a consequence of this configuration, convective gas flows can easily appear. The magnitude and effect of these flows on analytical performance are discussed and measures are suggested, permitting operation under diffusion controlled conditions. A critical comparison of classical constant temperature atomizers with state-of-the-art platform equipped ETAs is made and from this it is concluded that future ETA developments are likely to involve only minor modifications aiming at, e.g., the reduction of cycling times or the improvement of tube surface properties.

  4. Experiments with Ξ- atoms

    NASA Astrophysics Data System (ADS)

    Batty, C. J.; Friedman, E.; Gal, A.

    1999-01-01

    Experiments with Ξ- atoms are proposed in order to study the nuclear interaction of Ξ hyperons. The production of Ξ- in the (K-,K+) reaction, the Ξ- stopping in matter, and its atomic cascade are incorporated within a realistic evaluation of the results expected for Ξ- x-ray spectra across the periodic table, using an assumed Ξ-nucleus optical potential Vopt. Several optimal targets for measuring the strong-interaction shift and width of the x-ray transition to the ``last'' atomic level observed are singled out: F, Cl, I, and Pb. The sensitivity of these observables to the parameters of Vopt is considered. The relevance of such experiments is discussed in the context of strangeness -2 nuclear physics and multistrange nuclear matter. Finally, with particular reference to searches for the H dibaryon, the properties of Ξ-d atoms are also discussed. The role of Stark mixing and its effect on S and P state capture of Ξ- by the deuteron together with estimates of the resulting probability for producing the H dibaryon are considered in detail.

  5. Atomic collisions, inelastic indeed

    NASA Astrophysics Data System (ADS)

    Bercegol, Herve; Ferrando, Gwenael; Lehoucq, Roland

    At the turn of the twentieth century, a hot controversy raged about the ability of Boltzmann's framework to take care of irreversibility. The so-called Loschmidt's paradox progressively faded with time during the last hundred years, due to the predictive efficiency of statistical mechanics. However, one detail at the origin of the controversy - the elasticity of atomic collisions - was not completely challenged. A semi-classical treatment of two atoms interacting with the vacuum zero-point field permits to predict a friction force acting against the rotation of the pair of atoms. By its form and its level, the calculated torque is a candidate as a physical cause for diffusion of energy and angular momentum, and consequently for entropy growth. It opens the way to a revision of the standard vision of irreversibility. This presentation will focus on two points. First we will discuss the recent result in a broader context of electromagnetic interactions during microscopic collisions. The predicted friction phenomenon can be compared to and distinguished from Collision-Induced Emission and other types of inelastic collisions. Second we will investigate the consequences of the friction torque on calculated trajectories of colliding atoms, quantifying the generation of dimers linked by dispersion forces.

  6. Series expansions for the incomplete Lipschitz-Hankel integral Je 0(a, z)

    NASA Astrophysics Data System (ADS)

    Mechaik, Mehdi M.; Dvorak, Steven L.

    1995-09-01

    Bessel series expansions are derived for the incomplete Lipschitz-Hankel integralJe0(a, z). These expansions are obtained by using contour integration techniques to evaluate the inverse Laplace transform representation for Je0(a, z). It is shown that one of the expansions can be used as a convergent series expansion for one definition of the branch cut and as an asymptotic expansion if the branch cut is chosen differently. The effects of the branch cuts are demonstrated by plotting the terms in the series for interesting special cases. The Laplace transform technique used in this paper simplifies the derivation of the series expansions, provides information about the resulting branch cuts, yields integral representations for Je0(a, z), and allows the series expansions to be extended to complex values of z. These series expansions can be used together with the expansions for Ye0(a, z), which are obtained in a separate paper, to compute numerous other special functions, encountered in electromagnetic applications. These include: incomplete Lipschitz-Hankel integrals of the Hankel and modified Bessel form, incomplete cylindrical functions of Poisson form (incomplete Bessel, Struve, Hankel, and Macdonald functions), and incomplete Weber integrals (Lommel functions of two variables).

  7. H2A.Z acidic patch couples chromatin dynamics to regulation of gene expression programs during ESC differentiation.

    PubMed

    Subramanian, Vidya; Mazumder, Aprotim; Surface, Lauren E; Butty, Vincent L; Fields, Paul A; Alwan, Allison; Torrey, Lillian; Thai, Kevin K; Levine, Stuart S; Bathe, Mark; Boyer, Laurie A

    2013-01-01

    The histone H2A variant H2A.Z is essential for embryonic development and for proper control of developmental gene expression programs in embryonic stem cells (ESCs). Divergent regions of amino acid sequence of H2A.Z likely determine its functional specialization compared to core histone H2A. For example, H2A.Z contains three divergent residues in the essential C-terminal acidic patch that reside on the surface of the histone octamer as an uninterrupted acidic patch domain; however, we know little about how these residues contribute to chromatin structure and function. Here, we show that the divergent amino acids Gly92, Asp97, and Ser98 in the H2A.Z C-terminal acidic patch (H2A.Z(AP3)) are critical for lineage commitment during ESC differentiation. H2A.Z is enriched at most H3K4me3 promoters in ESCs including poised, bivalent promoters that harbor both activating and repressive marks, H3K4me3 and H3K27me3 respectively. We found that while H2A.Z(AP3) interacted with its deposition complex and displayed a highly similar distribution pattern compared to wild-type H2A.Z, its enrichment levels were reduced at target promoters. Further analysis revealed that H2A.Z(AP3) was less tightly associated with chromatin, suggesting that the mutant is more dynamic. Notably, bivalent genes in H2A.Z(AP3) ESCs displayed significant changes in expression compared to active genes. Moreover, bivalent genes in H2A.Z(AP3) ESCs gained H3.3, a variant associated with higher nucleosome turnover, compared to wild-type H2A.Z. We next performed single cell imaging to measure H2A.Z dynamics. We found that H2A.Z(AP3) displayed higher mobility in chromatin compared to wild-type H2A.Z by fluorescent recovery after photobleaching (FRAP). Moreover, ESCs treated with the transcriptional inhibitor flavopiridol resulted in a decrease in the H2A.Z(AP3) mobile fraction and an increase in its occupancy at target genes indicating that the mutant can be properly incorporated into chromatin. Collectively, our

  8. Atoms in astronomy

    NASA Technical Reports Server (NTRS)

    Blanchard, P. A.

    1976-01-01

    Aspects of electromagnetic radiation and atomic physics needed for an understanding of astronomical applications are explored. Although intended primarily for teachers, this brochure is written so that it can be distributed to students if desired. The first section, Basic Topics, is suitable for a ninth-grade general science class; the style is simple and repetitive, and no mathematics or physics background is required. The second section, Intermediate and Advanced Topics, requires a knowledge of the material in the first section and assumes a generally higher level of achievement and motivation on the part of the student. These latter topics might fit well into junior-level physics, chemistry, or earth-science courses. Also included are a glossary, a list of references and teaching aids, class exercises, and a question and answer section.

  9. Linear Atom Guides: Guiding Rydberg Atoms and Progress Toward an Atom Laser

    NASA Astrophysics Data System (ADS)

    Traxler, Mallory A.

    are also studied. Design and construction of a new linear magnetic atom guide is detailed. This guide beta has many improvements over the original guide alpha: a Zeeman slower, magnetic injection, a physical shutter, and surface adsorption evaporative cooling are some of the main changes. Testing of this new system is underway. It is hoped that the improvements to guide beta will yield an atom density sufficient to reach degeneracy, thereby forming a continuous BEC at the end of the guide. The BEC, which will be continuously replenished by the atoms within the guide, will be outcoupled to form a continuous atom laser.

  10. Parity-nonconserving interaction-induced light shifts in the {7S}_{1/2}-{6D}_{3/2} transition of the ultracold {^{210}{Fr}} atoms to probe new physics beyond the standard model

    NASA Astrophysics Data System (ADS)

    Aoki, T.; Torii, Y.; Sahoo, B. K.; Das, B. P.; Harada, K.; Hayamizu, T.; Sakamoto, K.; Kawamura, H.; Inoue, T.; Uchiyama, A.; Ito, S.; Yoshioka, R.; Tanaka, K. S.; Itoh, M.; Hatakeyama, A.; Sakemi, Y.

    2017-04-01

    We present an experimental technique to measure light shifts due to the nuclear spin independent (NSI) parity-nonconserving (PNC) interaction in the 7S_{1/2}-6D_{3/2} transition in ultracold {^{210}Fr} atoms. The approach we propose is similar to the one by Fortson (Phys Rev Lett 70:2383, 10) to measure the PNC-induced light shift which arises from the interference of parity nonconserving electric dipole transition and electric quadrupole transition amplitudes. Its major advantage is that it can treat more than 10^4 ultracold {^{210}Fr} atoms to enhance the shot noise limit. A relativistic coupled-cluster method has been employed to calculate the electric dipole transition amplitudes arising from the PNC interaction. Based on these calculations, we have evaluated the PNC-induced light shifts for transitions between the hyperfine levels of the 7S_{1/2} and 6D_{3/2} states and suitable transitions are identified for carrying out PNC measurements. It is possible in principle to probe new physics beyond the standard model with our proposed experimental scheme.

  11. K-shell radiation physics in low-to moderate-atomic-number z-pinch plasmas on the Z accelerator.

    SciTech Connect

    Clark, Robert W.; Maron, Yitzhak; Davis, J.; Apruzese, John P.; Whitney, Ken G.; LePell, Paul David; Velikovich, Aleksandr Lazarevich; Deeney, Christopher E.; McKenney, John Lee; Thornhill, Joseph W.; Oreshkin, V. I.; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Jones, Brent Manley; Safronova, Alla S.

    2004-12-01

    Dense z-pinches produced by 100 ns implosions of wire arrays or gas puffs produce substantial soft X-ray power. One class of z-pinch radiation sources includes low- to moderate-atomic-number K-shell radiators, such as aluminum and iron. These loads are designed for 1-10 keV K-shell X-ray generation, and offer opportunities for crystal spectroscopy that can reveal fundamental properties of the plasma when studied using plasma spectroscopic modeling. Typically these plasmas are characterized by ion densities of {approx} 10{sup 20} cm{sup -3}, diameters of 1-5 mm, electron temperatures up to several keV, and a range of opacities of the K-shell lines. Measurements from wire arrays on Sandia's 20 MA Z accelerator are presented along with collisional radiative and hydrodynamic simulations. The impact of opacity and 3D structure on non-LTE, non-diffusive radiation transport and X-ray production is discussed.

  12. Approach to chaos in ultracold atomic and molecular physics: Statistics of near-threshold bound states for Li+CaH and Li+CaF

    NASA Astrophysics Data System (ADS)

    Frye, Matthew D.; Morita, Masato; Vaillant, Christophe L.; Green, Dermot G.; Hutson, Jeremy M.

    2016-05-01

    We calculate near-threshold bound states and Feshbach resonance positions for atom-rigid-rotor models of the highly anisotropic systems Li+CaH and Li+CaF. We perform statistical analysis on the resonance positions to compare with the predictions of random matrix theory. For Li+CaH with total angular momentum J =0 we find fully chaotic behavior in both the nearest-neighbor spacing distribution and the level number variance. However, for J >0 we find different behavior due to the presence of a nearly conserved quantum number. Li+CaF (J =0 ) also shows apparently reduced levels of chaotic behavior despite its stronger effective coupling. This may indicate the development of another good quantum number relating to a bending motion of the complex. However, continuously varying the rotational constant over a wide range shows unexpected structure in the degree of chaotic behavior, including a dramatic reduction around the rotational constant of CaF. This demonstrates the complexity of the relationship between coupling and chaotic behavior.

  13. Specific Acetylation Patterns of H2A.Z Form Transient Interactions with the BPTF Bromodomain.

    PubMed

    Perell, Gabriella T; Mishra, Neeraj K; Sudhamalla, Babu; Ycas, Peter D; Islam, Kabirul; Pomerantz, William C K

    2017-09-05

    Post-translational lysine acetylation of histone tails affects both chromatin accessibility and recruitment of multifunctional bromodomain-containing proteins for modulating transcription. The bromodomain- and PHD finger-containing transcription factor (BPTF) regulates transcription but has also been implicated in high gene expression levels in a variety of cancers. In this report, the histone variant H2A.Z, which replaces H2A in chromatin, is evaluated for its affinity for BPTF with a specific recognition pattern of acetylated lysine residues of the N-terminal tail region. Although BPTF immunoprecipitates H2A.Z-containing nucleosomes, a direct interaction with its bromodomain has not been reported. Using protein-observed fluorine nuclear magnetic resonance (PrOF NMR) spectroscopy, we identified a diacetylation of H2A.Z on lysine residues 4 and 11, with the highest affinity for BPTF with a Kd of 780 μM. A combination of subsequent (1)H NMR Carr-Purcell-Meiboom-Gill experiments and photo-cross-linking further confirmed the specificity of the diacetylation pattern at lysines 4 and 11. Because of an adjacent PHD domain, this transient interaction may contribute to a higher-affinity bivalent interaction. Further evaluation of specificity toward a set of bromodomains, including two BET bromodomains (Brd4 and BrdT) and two Plasmodium falciparum bromodomains, resulted in one midmicromolar affinity binder, PfGCN5 (Kd = 650 μM). With these biochemical experiments, we have identified a direct interaction of histone H2A.Z with bromodomains with a specific acetylation pattern that further supports the role of H2A.Z in epigenetic regulation.

  14. International Conference on the Physics of Electronic and Atomic Collisions. Participants List (16th), Held in New York, New York on 26 July-1 August 1989

    DTIC Science & Technology

    1989-08-01

    NY 11973 CHAPEL HILL, NC 27599 OAK RIDGE, TN 37831-6372 USA USA USA H. HARVEY MICHELS FREDERICK H. MIES WALTER 6. MEYERHOF UNITED TECHNOLOGIES N.I.S.T... VACHON DEPARTMENT OF CHEMISTRYCALCUTTA, W. BENGAL, 700032 QUEBEC, QUEBEC, 61K 7P4 STONY BROOK, NY 11794-3400INDIA CANADA USA Nf. EUGEN RUDD 4.R.H...OF ROORKEE 4800 OAK GROVE DRIVE PAV. VACHON DEPT OF PHYSICS PASADENA, CA 91109 QUEBEC, QUEBEC, 61K 7P4 ROORKEE, UP 247667 USA CANADA INDIA SUBHANKAR

  15. Correlation of embryonic skeletal muscle myotube physical characteristics with contractile force generation on an atomic force microscope-based bio-microelectromechanical systems device

    PubMed Central

    Pirozzi, K. L.; Long, C. J.; McAleer, C. W.; Smith, A. S. T.; Hickman, J. J.

    2013-01-01

    Rigorous analysis of muscle function in in vitro systems is needed for both acute and chronic biomedical applications. Forces generated by skeletal myotubes on bio-microelectromechanical cantilevers were calculated using a modified version of Stoney's thin-film equation and finite element analysis (FEA), then analyzed for regression to physical parameters. The Stoney's equation results closely matched the more intensive FEA and the force correlated to cross-sectional area (CSA). Normalizing force to measured CSA significantly improved the statistical sensitivity and now allows for close comparison of in vitro data to in vivo measurements for applications in exercise physiology, robotics, and modeling neuromuscular diseases. PMID:24046483

  16. Correlation of embryonic skeletal muscle myotube physical characteristics with contractile force generation on an atomic force microscope-based bio-microelectromechanical systems device

    NASA Astrophysics Data System (ADS)

    Pirozzi, K. L.; Long, C. J.; McAleer, C. W.; Smith, A. S. T.; Hickman, J. J.

    2013-08-01

    Rigorous analysis of muscle function in in vitro systems is needed for both acute and chronic biomedical applications. Forces generated by skeletal myotubes on bio-microelectromechanical cantilevers were calculated using a modified version of Stoney's thin-film equation and finite element analysis (FEA), then analyzed for regression to physical parameters. The Stoney's equation results closely matched the more intensive FEA and the force correlated to cross-sectional area (CSA). Normalizing force to measured CSA significantly improved the statistical sensitivity and now allows for close comparison of in vitro data to in vivo measurements for applications in exercise physiology, robotics, and modeling neuromuscular diseases.

  17. Anp32e, a higher eukaryotic histone chaperone directs preferential recognition for H2A.Z

    PubMed Central

    Mao, Zhuo; Pan, Lu; Wang, Weixiang; Sun, Jian; Shan, Shan; Dong, Qiang; Liang, Xiaoping; Dai, Linchang; Ding, Xiaojun; Chen, She; Zhang, Zhuqiang; Zhu, Bing; Zhou, Zheng

    2014-01-01

    H2A.Z is a highly conserved histone variant in all species. The chromatin deposition of H2A.Z is specifically catalyzed by the yeast chromatin remodeling complex SWR1 and its mammalian counterpart SRCAP. However, the mechanism by which H2A.Z is preferentially recognized by non-histone proteins remains elusive. Here we identified Anp32e, a novel higher eukaryote-specific histone chaperone for H2A.Z. Anp32e preferentially associates with H2A.Z-H2B dimers rather than H2A-H2B dimers in vitro and in vivo and dissociates non-nucleosomal aggregates formed by DNA and H2A-H2B. We determined the crystal structure of the Anp32e chaperone domain (186-232) in complex with the H2A.Z-H2B dimer. In this structure, the region containing Anp32e residues 214-224, which is absent in other Anp32 family proteins, specifically interacts with the extended H2A.Z αC helix, which exhibits an unexpected conformational change. Genome-wide profiling of Anp32e revealed a remarkable co-occupancy between Anp32e and H2A.Z. Cells overexpressing Anp32e displayed a strong global H2A.Z loss at the +1 nucleosomes, whereas cells depleted of Anp32e displayed a moderate global H2A.Z increase at the +1 nucleosomes. This suggests that Anp32e may help to resolve the non-nucleosomal H2A.Z aggregates and also facilitate the removal of H2A.Z at the +1 nucleosomes, and the latter may help RNA polymerase II to pass the first nucleosomal barrier. PMID:24613878

  18. Optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

    2013-12-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  19. History of Physics.

    ERIC Educational Resources Information Center

    Moyer, Albert E.

    1985-01-01

    Discusses the history of American physics, indicating that much effort has been on the atomic bond and high-energy physics, to the detriment of other topics and areas. To offset this tendency, significant research is going on in the history of solid-state physics, with glimmerings in the history of physics education. (JN)

  20. Multivalent binding of PWWP2A to H2A.Z regulates mitosis and neural crest differentiation.

    PubMed

    Pünzeler, Sebastian; Link, Stephanie; Wagner, Gabriele; Keilhauer, Eva C; Kronbeck, Nina; Spitzer, Ramona Mm; Leidescher, Susanne; Markaki, Yolanda; Mentele, Edith; Regnard, Catherine; Schneider, Katrin; Takahashi, Daisuke; Kusakabe, Masayuki; Vardabasso, Chiara; Zink, Lisa M; Straub, Tobias; Bernstein, Emily; Harata, Masahiko; Leonhardt, Heinrich; Mann, Matthias; Rupp, Ralph Aw; Hake, Sandra B

    2017-08-01

    Replacement of canonical histones with specialized histone variants promotes altering of chromatin structure and function. The essential histone variant H2A.Z affects various DNA-based processes via poorly understood mechanisms. Here, we determine the comprehensive interactome of H2A.Z and identify PWWP2A as a novel H2A.Z-nucleosome binder. PWWP2A is a functionally uncharacterized, vertebrate-specific protein that binds very tightly to chromatin through a concerted multivalent binding mode. Two internal protein regions mediate H2A.Z-specificity and nucleosome interaction, whereas the PWWP domain exhibits direct DNA binding. Genome-wide mapping reveals that PWWP2A binds selectively to H2A.Z-containing nucleosomes with strong preference for promoters of highly transcribed genes. In human cells, its depletion affects gene expression and impairs proliferation via a mitotic delay. While PWWP2A does not influence H2A.Z occupancy, the C-terminal tail of H2A.Z is one important mediator to recruit PWWP2A to chromatin. Knockdown of PWWP2A in Xenopus results in severe cranial facial defects, arising from neural crest cell differentiation and migration problems. Thus, PWWP2A is a novel H2A.Z-specific multivalent chromatin binder providing a surprising link between H2A.Z, chromosome segregation, and organ development. © 2017 The Authors.

  1. H2A.Z marks antisense promoters and has positive effects on antisense transcript levels in budding yeast.

    PubMed

    Gu, Muxin; Naiyachit, Yanin; Wood, Thomas J; Millar, Catherine B

    2015-02-19

    The histone variant H2A.Z, which has been reported to have both activating and repressive effects on gene expression, is known to occupy nucleosomes at the 5' ends of protein-coding genes. We now find that H2A.Z is also significantly enriched in gene coding regions and at the 3' ends of genes in budding yeast, where it co-localises with histone marks associated with active promoters. By comparing H2A.Z binding to global gene expression in budding yeast strains engineered so that normally unstable transcripts are abundant, we show that H2A.Z is required for normal levels of antisense transcripts as well as sense ones. High levels of H2A.Z at antisense promoters are associated with decreased antisense transcript levels when H2A.Z is deleted, indicating that H2A.Z has an activating effect on antisense transcripts. Decreases in antisense transcripts affected by H2A.Z are accompanied by increased levels of paired sense transcripts. The effect of H2A.Z on protein coding gene expression is a reflection of its importance for normal levels of both sense and antisense transcripts.

  2. Ion-Atom Cold Collisions and Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Maleki, Lute; Tjoelker, Robert L.

    1997-01-01

    Collisions between ultracold neutral atoms have for some time been the subject of investigation, initially with hydrogen and more recently with laser cooled alkali atoms. Advances in laser cooling and trapping of neutral atoms in a Magneto-Optic Trap (MOT) have made cold atoms available as the starting point for many laser cooled atomic physics investigations. The most spectacularly successful of these, the observation of Bose-Einstein Condensation (BEC) in a dilute ultra-cold spin polarized atomic vapor, has accelerated the study of cold collisions. Experimental and theoretical studies of BEC and the long range interaction between cold alkali atoms is at the boundary of atomic and low temperature physics. Such studies have been difficult and would not have been possible without the development and advancement of laser cooling and trapping of neutral atoms. By contrast, ion-atom interactions at low temperature, also very difficult to study prior to modern day laser cooling, have remained largely unexplored. But now, many laboratories worldwide have almost routine access to cold neutral atoms. The combined technologies of ion trapping, together with laser cooling of neutrals has made these studies experimentally feasible and several very important, novel applications might come out of such investigations . This paper is an investigation of ion-atom interactions in the cold and ultra-cold temperature regime. Some of the collisional ion-atom interactions present at room temperature are very much reduced in the low temperature regime. Reaction rates for charge transfer between unlike atoms, A + B(+) approaches A(+) + B, are expected to fall rapidly with temperature, approximately as T(sup 5/2). Thus, cold mixtures of atoms and ions are expected to coexist for very long times, unlike room temperature mixtures of the same ion-atom combination. Thus, it seems feasible to cool ions via collisions with laser cooled atoms. Many of the conventional collisional interactions

  3. Ion-Atom Cold Collisions and Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Maleki, Lute; Tjoelker, Robert L.

    1997-01-01

    Collisions between ultracold neutral atoms have for some time been the subject of investigation, initially with hydrogen and more recently with laser cooled alkali atoms. Advances in laser cooling and trapping of neutral atoms in a Magneto-Optic Trap (MOT) have made cold atoms available as the starting point for many laser cooled atomic physics investigations. The most spectacularly successful of these, the observation of Bose-Einstein Condensation (BEC) in a dilute ultra-cold spin polarized atomic vapor, has accelerated the study of cold collisions. Experimental and theoretical studies of BEC and the long range interaction between cold alkali atoms is at the boundary of atomic and low temperature physics. Such studies have been difficult and would not have been possible without the development and advancement of laser cooling and trapping of neutral atoms. By contrast, ion-atom interactions at low temperature, also very difficult to study prior to modern day laser cooling, have remained largely unexplored. But now, many laboratories worldwide have almost routine access to cold neutral atoms. The combined technologies of ion trapping, together with laser cooling of neutrals has made these studies experimentally feasible and several very important, novel applications might come out of such investigations . This paper is an investigation of ion-atom interactions in the cold and ultra-cold temperature regime. Some of the collisional ion-atom interactions present at room temperature are very much reduced in the low temperature regime. Reaction rates for charge transfer between unlike atoms, A + B(+) approaches A(+) + B, are expected to fall rapidly with temperature, approximately as T(sup 5/2). Thus, cold mixtures of atoms and ions are expected to coexist for very long times, unlike room temperature mixtures of the same ion-atom combination. Thus, it seems feasible to cool ions via collisions with laser cooled atoms. Many of the conventional collisional interactions

  4. AC Zeeman potentials for atom chip-based ultracold atoms

    NASA Astrophysics Data System (ADS)

    Fancher, Charles; Pyle, Andrew; Ziltz, Austin; Aubin, Seth

    2015-05-01

    We present experimental and theoretical progress on using the AC Zeeman force produced by microwave magnetic near-fields from an atom chip to manipulate and eventually trap ultracold atoms. These AC Zeeman potentials are inherently spin-dependent and can be used to apply qualitatively different potentials to different spin states simultaneously. Furthermore, AC Zeeman traps are compatible with the large DC magnetic fields necessary for accessing Feshbach resonances. Applications include spin-dependent trapped atom interferometry and experiments in 1D many-body physics. Initial experiments and results are geared towards observing the bipolar detuning-dependent nature of the AC Zeeman force at 6.8 GHz with ultracold 87Rb atoms trapped in the vicinity of an atom chip. Experimental work is also underway towards working with potassium isotopes at frequencies of 1 GHz and below. Theoretical work is focused on atom chip designs for AC Zeeman traps produced by magnetic near-fields, while also incorporating the effect of the related electric near-fields. Electromagnetic simulations of atom chip circuits are used for mapping microwave propagation in on-chip transmission line structures, accounting for the skin effect, and guiding impedance matching.

  5. Atomic oxygen testing with thermal atom systems - A critical evaluation

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Albyn, Keith; Leger, Lubert J.

    1991-01-01

    The use of thermal atom (kinetic energy near 0.04 eV) test methods as a materials selection and screening technique for LEO spacecraft is critically evaluated in this paper. The physics and chemistry of the thermal atom environments are shown to produce specific mass loss rates (mg/sq cm per min) and reaction efficiencies (Re) radically different from those produced in the LEO environment. A response surface study shows that specific mass loss rates change rapidly with plasma-asher parameters and seldom agree with flight data. FEP Teflon is shown to react by a different mechanism than Kapton, polyethylene, or graphite. The Re (Re = volume of material removed/oxygen atom) of Kapton, polyethylene, Mylar, Tedlar, FEP Teflon, and graphite measured in a flowing afterglow apparatus are 0.001 to 0.0001 those measured with high-energy atoms (kinetic energy 1.5 eV or greater) in beam systems or in LEO. The effect of sample temperature and atom impact energy on Re is discussed. A simple kinetic model describing the reaction of atomic oxygen with polymer surfaces is developed. Guidelines and recommendations for thermal atom testing and interpretation of test results are presented.

  6. Atomic oxygen testing with thermal atom systems - A critical evaluation

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Albyn, Keith; Leger, Lubert J.

    1991-01-01

    The use of thermal atom (kinetic energy near 0.04 eV) test methods as a materials selection and screening technique for LEO spacecraft is critically evaluated in this paper. The physics and chemistry of the thermal atom environments are shown to produce specific mass loss rates (mg/sq cm per min) and reaction efficiencies (Re) radically different from those produced in the LEO environment. A response surface study shows that specific mass loss rates change rapidly with plasma-asher parameters and seldom agree with flight data. FEP Teflon is shown to react by a different mechanism than Kapton, polyethylene, or graphite. The Re (Re = volume of material removed/oxygen atom) of Kapton, polyethylene, Mylar, Tedlar, FEP Teflon, and graphite measured in a flowing afterglow apparatus are 0.001 to 0.0001 those measured with high-energy atoms (kinetic energy 1.5 eV or greater) in beam systems or in LEO. The effect of sample temperature and atom impact energy on Re is discussed. A simple kinetic model describing the reaction of atomic oxygen with polymer surfaces is developed. Guidelines and recommendations for thermal atom testing and interpretation of test results are presented.

  7. Unique residues on the H2A.Z containing nucleosome surface are important for Xenopus laevis development.

    PubMed

    Ridgway, Patricia; Brown, Karl D; Rangasamy, Danny; Svensson, Ulrica; Tremethick, David J

    2004-10-15

    Critical to vertebrate development is a complex program of events that establishes specialized tissues and organs from a single fertilized cell. Transitions in chromatin architecture, through alterations in its composition and modification markings, characterize early development. A variant of the H2A core histone, H2A.Z, is essential for development of both Drosophila and mice. We recently showed that H2A.Z is required for proper chromosome segregation. Whether H2A.Z has additional specific functions during early development remains unknown. Here we demonstrate that depletion of H2A.Z by RNA interference perturbs Xenopus laevis development at gastrulation leading to embryos with malformed, shortened trunks. Consistent with this result, whole embryo in situ hybridization indicates that endogenous expression of H2A.Z is highly enriched in the notochord. H2A.Z modifies the surface of a canonical nucleosome by creating an extended acidic patch and a metal ion-binding site stabilized by two histidine residues. To examine the significance of these specific surface regions in vivo, we investigated the consequences of overexpressing H2A.Z and mutant proteins during X. laevis development. Overexpression of H2A.Z slowed development following gastrulation. Altering the extended acidic patch of H2A.Z reversed this effect. Remarkably, modification of a single stabilizing histidine residue located on the exposed surface of an H2A.Z containing nucleosome was sufficient to disrupt normal trunk formation mimicking the effect observed by RNA interference. Taken together, these results argue that key determinants located on the surface of an H2A.Z nucleosome play an important specific role during embryonic patterning and provide a link between a chromatin structural modification and normal vertebrate development.

  8. A Combination of H2A.Z and H4 Acetylation Recruits Brd2 to Chromatin during Transcriptional Activation

    PubMed Central

    Draker, Ryan; Ng, Marlee K.; Sarcinella, Elizabeth; Ignatchenko, Vladimir; Kislinger, Thomas; Cheung, Peter

    2012-01-01

    H2A.Z is an essential histone variant that has been implicated to have multiple chromosomal functions. To understand how H2A.Z participates in such diverse activities, we sought to identify downstream effector proteins that are recruited to chromatin via H2A.Z. For this purpose, we developed a nucleosome purification method to isolate H2A.Z-containing nucleosomes from human cells and used mass spectrometry to identify the co-purified nuclear proteins. Through stringent filtering, we identified the top 21 candidates, many of which have conserved structural motifs that bind post-translationally modified histones. We further validated the biological significance of one such candidate, Brd2, which is a double-bromodomain-containing protein known to function in transcriptional activation. We found that Brd2's preference for H2A.Z nucleosomes is mediated through a combination of hyperacetylated H4 on these nucleosomes, as well as additional features on H2A.Z itself. In addition, comparison of nucleosomes containing either H2A.Z-1 or H2A.Z-2 isoforms showed that significantly more Brd2 co-purifies with the former, suggesting these two isoforms engage different downstream effector proteins. Consistent with these biochemical analyses, we found that Brd2 is recruited to AR–regulated genes in an H2A.Z-dependent manner and that chemical inhibition of Brd2 recruitment greatly inhibits AR–regulated gene expression. Taken together, we propose that Brd2 is a key downstream mediator that links H2A.Z and transcriptional activation of AR–regulated genes. Moreover, this study validates the approach of using proteomics to identify nucleosome-interacting proteins in order to elucidate downstream mechanistic functions associated with the histone variant H2A.Z. PMID:23144632

  9. Dual Role of the Histone Variant H2A.Z in Transcriptional Regulation of Stress-Response Genes.

    PubMed

    Sura, Weronika; Kabza, Michał; Karlowski, Wojciech M; Bieluszewski, Tomasz; Kus-Slowinska, Marta; Pawełoszek, Łukasz; Sadowski, Jan; Ziolkowski, Piotr A

    2017-04-01

    The influence of the histone variant H2A.Z on transcription remains a long-standing conundrum. Here, by analyzing the actin-related protein6 mutant, which is impaired in H2A.Z deposition, and by H2A.Z profiling in stress conditions, we investigated the impact of this histone variant on gene expression in Arabidopsis thaliana We demonstrate that the arp6 mutant exhibits anomalies in response to osmotic stress. Indeed, stress-responsive genes are overrepresented among those hyperactive in arp6. In wild-type plants, these genes exhibit high levels of H2A.Z in the gene body. Furthermore, we observed that in drought-responsive genes, levels of H2A.Z in the gene body correlate with transcript levels. H2A.Z occupancy, but not distribution, changes in parallel with transcriptional changes. In particular, we observed H2A.Z loss upon transcriptional activation and H2A.Z gain upon repression. These data suggest that H2A.Z has a repressive role in transcription and counteracts unwanted expression in noninductive conditions. However, reduced activity of some genes in arp6 is associated with distinct behavior of H2A.Z at their +1 nucleosome, which exemplifies the requirement of this histone for transcription. Our data support a model where H2A.Z in gene bodies has a strong repressive effect on transcription, whereas in +1 nucleosomes, it is important for maintaining the activity of some genes. © 2017 ASPB.

  10. The Atom and the Ocean, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Hull, E. W. Seabrook

    Included is a brief description of the characteristics of the ocean, its role as a resource for food and minerals, its composition and its interactions with land and air. The role of atomic physics in oceanographic exploration is illustrated by the use of nuclear reactors to power surface and submarine research vessels and the design and use of…

  11. Transcriptional and epigenetic functions of histone variant H2A.Z.

    PubMed

    Draker, Ryan; Cheung, Peter

    2009-02-01

    The chromatin organization of a genome ultimately dictates the gene expression profile of the cell. It is now well recognized that key mechanisms that regulate chromatin structure include post-translational modifications of histones and the incorporation of histone variants at strategic sites within the genome. H2A.Z is a variant of H2A that is localized to the 5' end of many genes and is required for proper regulation of gene expression. However, its precise function in the transcription process is not yet well defined. In this review, we discuss some of the recent findings related to this histone variant, how it associates with other histone epigenetic marks, and how post-translational modifications of H2A.Z further define its function.

  12. Atomic memory

    NASA Astrophysics Data System (ADS)

    Brewer, R. G.; Hahn, E. L.

    1984-12-01

    The fundamental principles of atomic-memory effects related to the Loschmidt paradox in the second law of thermodynamics are introduced and illustrated with simple analogies, photographs, and diagrams; and the results of RF and laser experiments are summarized. Nuclear-spin echoes in response to RF pulses and the NMR free-induction decay phenomenon are described, and the extension of these concepts to the visible spectrum in laser-frequency-switching and multipulsed-laser experiments is examined with an emphasis on studies of free-induction decay in LaF3 crystals containing Pr impurities (DeVoe and Brewster). The laser-induced phenomena can be applied to studies of intramolecular and intermolecular interactions, and an improved understanding of the RF effects is needed to enhance the performance of medical NMR imaging systems.

  13. Atomic magnetometer

    DOEpatents

    Schwindt, Peter [Albuquerque, NM; Johnson, Cort N [Albuquerque, NM

    2012-07-03

    An atomic magnetometer is disclosed which uses a pump light beam at a D1 or D2 transition of an alkali metal vapor to magnetically polarize the vapor in a heated cell, and a probe light beam at a different D2 or D1 transition to sense the magnetic field via a polarization rotation of the probe light beam. The pump and probe light beams are both directed along substantially the same optical path through an optical waveplate and through the heated cell to an optical filter which blocks the pump light beam while transmitting the probe light beam to one or more photodetectors which generate electrical signals to sense the magnetic field. The optical waveplate functions as a quarter waveplate to circularly polarize the pump light beam, and as a half waveplate to maintain the probe light beam linearly polarized.

  14. Physical understanding of trends in current collapse with atomic layer deposited dielectrics in AlGaN/GaN MOS heterojunction FETs

    NASA Astrophysics Data System (ADS)

    Ramanan, Narayanan; Lee, Bongmook; Misra, Veena

    2016-03-01

    Many passivation dielectrics are pursued for suppressing current collapse due to trapping/detrapping of access-region surface traps in AlGaN/GaN based metal oxide semiconductor heterojuction field effect transistors (MOS-HFETs). The suppression of current collapse can potentially be achieved either by reducing the interaction of surface traps with the gate via surface leakage current reduction, or by eliminating surface traps that can interact with the gate. But, the latter is undesirable since a high density of surface donor traps is required to sustain a high 2D electron gas density at the AlGaN/GaN heterointerface and provide a low ON-resistance. This presents a practical trade-off wherein a passivation dielectric with the optimal surface trap characteristics and minimal surface leakage is to be chosen. In this work, we compare MOS-HFETs fabricated with popular ALD gate/passivation dielectrics like SiO2, Al2O3, HfO2 and HfAlO along with an additional thick plasma-enhanced chemical vapor deposition SiO2 passivation. It is found that after annealing in N2 at 700 °C, the stack containing ALD HfAlO provides a combination of low surface leakage and a high density of shallow donor traps. Physics-based TCAD simulations confirm that this combination of properties helps quick de-trapping and minimal current collapse along with a low ON resistance.

  15. Quantum information with Rydberg atoms

    SciTech Connect

    Saffman, M.; Walker, T. G.; Moelmer, K.

    2010-07-15

    Rydberg atoms with principal quantum number n>>1 have exaggerated atomic properties including dipole-dipole interactions that scale as n{sup 4} and radiative lifetimes that scale as n{sup 3}. It was proposed a decade ago to take advantage of these properties to implement quantum gates between neutral atom qubits. The availability of a strong long-range interaction that can be coherently turned on and off is an enabling resource for a wide range of quantum information tasks stretching far beyond the original gate proposal. Rydberg enabled capabilities include long-range two-qubit gates, collective encoding of multiqubit registers, implementation of robust light-atom quantum interfaces, and the potential for simulating quantum many-body physics. The advances of the last decade are reviewed, covering both theoretical and experimental aspects of Rydberg-mediated quantum information processing.

  16. H2A.Z.1 mono-ubiquitylation antagonizes BRD2 to maintain poised chromatin in ESCs

    PubMed Central

    Surface, Lauren E.; Fields, Paul A.; Subramanian, Vidya; Behmer, Russell; Udeshi, Namrata; Peach, Sally E.; Jaffe, Jacob D.; Boyer, Laurie A.

    2016-01-01

    SUMMARY Histone variant H2A.Z occupies the promoters of active and poised, bivalent genes in ESCs to regulate developmental programs, yet how it contributes to these contrasting states is poorly understood. Here, we investigate the function of H2A.Z.1 mono-ubiquitylation (H2A.Z.1ub) by mutation of the PRC1 target residues (H2A.Z.1K3R3). We show that H2A.Z.1K3R3 is properly incorporated at target promoters in murine ESCs (mESCs), however, loss of mono-ubiquitylation leads to de-repression of bivalent genes, loss of Polycomb binding, and to faulty lineage commitment. Using quantitative proteomics, we find that tandem bromodomain proteins, including the BET family member Brd2, are enriched in H2A.Z.1 chromatin. We further show that Brd2 is gained at de-repressed promoters in H2A.Z.1K3R3 mESCs whereas Brd2 inhibition restores gene silencing at these sites. Together, our study reveals an antagonistic relationship between H2A.Z.1ub and Brd2 to regulate the transcriptional balance at bivalent genes to enable proper execution of developmental programs. PMID:26804911

  17. Differential deposition of H2A.Z in rice seedling tissue during the day-night cycle.

    PubMed

    Zhang, Kang; Xu, Wenying; Wang, Chunchao; Yi, Xin; Su, Zhen

    2017-03-04

    Chromatin structure has an important role in modulating gene expression. The incorporation of histone variants into the nucleosome leads to important changes in the chromatin structure. The histone variant H2A.Z is highly conserved between different species of fungi, animals, and plants. However, dynamic changes to H2A.Z in rice have not been reported during the day-night cycle. In this study, we generated genome wide maps of H2A.Z for day and night time in harvested seedling tissues by combining chromatin immunoprecipitation and high-throughput sequencing. The analysis results for the H2A.Z data sets detected 7099 genes with higher depositions of H2A.Z in seedling tissues harvested at night compared with seedling tissues harvested during the day, whereas 4597 genes had higher H2A.Z depositions in seedlings harvested during the day. The gene expression profiles data suggested that H2A.Z probably negatively regulated gene expression during the day-night cycle and was involved in many important biologic processes. In general, our results indicated that H2A.Z may play an important role in plant responses to the diurnal oscillation process.

  18. A Simple Relativistic Bohr Atom

    ERIC Educational Resources Information Center

    Terzis, Andreas F.

    2008-01-01

    A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…

  19. A Simple Relativistic Bohr Atom

    ERIC Educational Resources Information Center

    Terzis, Andreas F.

    2008-01-01

    A simple concise relativistic modification of the standard Bohr model for hydrogen-like atoms with circular orbits is presented. As the derivation requires basic knowledge of classical and relativistic mechanics, it can be taught in standard courses in modern physics and introductory quantum mechanics. In addition, it can be shown in a class that…

  20. Atomism from Newton to Dalton.

    ERIC Educational Resources Information Center

    Schofield, Robert E.

    1981-01-01

    Indicates that although Newton's achievements were rooted in an atomistic theory of matter resembling aspects of modern nuclear physics, Dalton developed his chemical atomism on the basis of the character of the gross behavior of substances rather than their particulate nature. (Author/SK)

  1. Atomism from Newton to Dalton.

    ERIC Educational Resources Information Center

    Schofield, Robert E.

    1981-01-01

    Indicates that although Newton's achievements were rooted in an atomistic theory of matter resembling aspects of modern nuclear physics, Dalton developed his chemical atomism on the basis of the character of the gross behavior of substances rather than their particulate nature. (Author/SK)

  2. Atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity, respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous - whose rates are related by a non-constant function beta sub a - is demonstrated. The cosmological character of beta sub a is also discussed.

  3. Theoretical Calculations of Atomic Data for Spectroscopy

    NASA Technical Reports Server (NTRS)

    Bautista, Manuel A.

    2000-01-01

    Several different approximations and techniques have been developed for the calculation of atomic structure, ionization, and excitation of atoms and ions. These techniques have been used to compute large amounts of spectroscopic data of various levels of accuracy. This paper presents a review of these theoretical methods to help non-experts in atomic physics to better understand the qualities and limitations of various data sources and assess how reliable are spectral models based on those data.

  4. Sensing mode atomic force microscope

    DOEpatents

    Hough, Paul V. C.; Wang, Chengpu

    2003-01-01

    An atomic force microscope utilizes a pulse release system and improved method of operation to minimize contact forces between a probe tip affixed to a flexible cantilever and a specimen being measured. The pulse release system includes a magnetic particle affixed proximate the probe tip and an electromagnetic coil. When energized, the electromagnetic coil generates a magnetic field which applies a driving force on the magnetic particle sufficient to overcome adhesive forces exhibited between the probe tip and specimen. The atomic force microscope includes two independently displaceable piezo elements operable along a Z-axis. A controller drives the first Z-axis piezo element to provide a controlled approach between the probe tip and specimen up to a point of contact between the probe tip and specimen. The controller then drives the first Z-axis piezo element to withdraw the cantilever from the specimen. The controller also activates the pulse release system which drives the probe tip away from the specimen during withdrawal. Following withdrawal, the controller adjusts the height of the second Z-axis piezo element to maintain a substantially constant approach distance between successive samples.

  5. Orientational atom interferometers sensitive to gravitational waves

    SciTech Connect

    Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas

    2010-02-15

    We present an atom interferometer that differs from common atom interferometers as it is not based on the spatial splitting of electronic wave functions, but on orienting atoms in space. As an example we present how an orientational atom interferometer based on highly charged hydrogen-like atoms is affected by gravitational waves. We show that a monochromatic gravitational wave will cause a frequency shift that scales with the binding energy of the system rather than with its physical dimension. For a gravitational wave amplitude of h=10{sup -23} the frequency shift is of the order of 110 {mu}Hz for an atom interferometer based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current atom interferometers in 1 s.

  6. Knowledge Extraction from Atomically Resolved Images.

    PubMed

    Vlcek, Lukas; Maksov, Artem; Pan, Minghu; Vasudevan, Rama K; Kalinin, Sergei V

    2017-10-03

    Tremendous strides in experimental capabilities of scanning transmission electron microscopy and scanning tunneling microscopy (STM) over the past 30 years made atomically resolved imaging routine. However, consistent integration and use of atomically resolved data with generative models is unavailable, so information on local thermodynamics and other microscopic driving forces encoded in the observed atomic configurations remains hidden. Here, we present a framework based on statistical distance minimization to consistently utilize the information available from atomic configurations obtained from an atomically resolved image and extract meaningful physical interaction parameters. We illustrate the applicability of the framework on an STM image of a FeSexTe1-x superconductor, with the segregation of the chalcogen atoms investigated using a nonideal interacting solid solution model. This universal method makes full use of the microscopic degrees of freedom sampled in an atomically resolved image and can be extended via Bayesian inference toward unbiased model selection with uncertainty quantification.

  7. Electron-Atom Collisions in Gases

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  8. Index to the Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This index was prepared for the set of 51 booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school students and their teachers. In addition to the index, a complete list of the series is provided in which the booklets are grouped into the categories of physics, chemistry, biology, nuclear…

  9. Electron-Atom Collisions in Gases

    ERIC Educational Resources Information Center

    Kraftmakher, Yaakov

    2013-01-01

    Electron-atom collisions in gases are an aspect of atomic physics. Three experiments in this field employing a thyratron are described: (i) the Ramsauer-Townsend effect, (ii) the excitation and ionization potentials of xenon and (iii) the ion-electron recombination after interrupting the electric discharge.

  10. Expression of P. falciparum var Genes Involves Exchange of the Histone Variant H2A.Z at the Promoter

    PubMed Central

    Petter, Michaela; Lee, Chin Chin; Byrne, Timothy J.; Boysen, Katja E.; Volz, Jennifer; Ralph, Stuart A.; Cowman, Alan F.; Brown, Graham V.; Duffy, Michael F.

    2011-01-01

    Plasmodium falciparum employs antigenic variation to evade the human immune response by switching the expression of different variant surface antigens encoded by the var gene family. Epigenetic mechanisms including histone modifications and sub-nuclear compartmentalization contribute to transcriptional regulation in the malaria parasite, in particular to control antigenic variation. Another mechanism of epigenetic control is the exchange of canonical histones with alternative variants to generate functionally specialized chromatin domains. Here we demonstrate that the alternative histone PfH2A.Z is associated with the epigenetic regulation of var genes. In many eukaryotic organisms the histone variant H2A.Z mediates an open chromatin structure at promoters and facilitates diverse levels of regulation, including transcriptional activation. Throughout the asexual, intraerythrocytic lifecycle of P. falciparum we found that the P. falciparum ortholog of H2A.Z (PfH2A.Z) colocalizes with histone modifications that are characteristic of transcriptionally-permissive euchromatin, but not with markers of heterochromatin. Consistent with this finding, antibodies to PfH2A.Z co-precipitate the permissive modification H3K4me3. By chromatin-immunoprecipitation we show that PfH2A.Z is enriched in nucleosomes around the transcription start site (TSS) in both transcriptionally active and silent stage-specific genes. In var genes, however, PfH2A.Z is enriched at the TSS only during active transcription in ring stage parasites. Thus, in contrast to other genes, temporal var gene regulation involves histone variant exchange at promoter nucleosomes. Sir2 histone deacetylases are important for var gene silencing and their yeast ortholog antagonises H2A.Z function in subtelomeric yeast genes. In immature P. falciparum parasites lacking Sir2A or Sir2B high var transcription levels correlate with enrichment of PfH2A.Z at the TSS. As Sir2A knock out parasites mature the var genes are

  11. AtomPy: an open atomic-data curation environment

    NASA Astrophysics Data System (ADS)

    Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

    2014-06-01

    We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

  12. A Miniature Wide Band Atomic Magnetometer

    DTIC Science & Technology

    2011-12-01

    Technology PCB – Printed Circuit Board Physics Package – The physical structure of the cell, laser diode , and light source. QAM – Quadrature...single, resonant laser . (b) Two- laser design in which one laser , circularly polarized and tuned to the optical resonance, pumps the atoms, and a second... pump laser creates a polarization in the atoms, which is probed by a weak linearly polarized VCSEL. The modulation of the polarization rotation of the

  13. "Bohr's Atomic Model."

    ERIC Educational Resources Information Center

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  14. "Bohr's Atomic Model."

    ERIC Educational Resources Information Center

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  15. The atomic orbitals of the topological atom.

    PubMed

    Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István

    2013-06-07

    The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.

  16. Positron Physics

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2003-01-01

    I will give a review of the history of low-energy positron physics, experimental and theoretical, concentrating on the type of work pioneered by John Humberston and the positronics group at University College. This subject became a legitimate subfield of atomic physics under the enthusiastic direction of the late Sir Harrie Massey, and it attracted a diverse following throughout the world. At first purely theoretical, the subject has now expanded to include high brightness beams of low-energy positrons, positronium beams, and, lately, experiments involving anti-hydrogen atoms. The theory requires a certain type of persistence in its practitioners, as well as an eagerness to try new mathematical and numerical techniques. I will conclude with a short summary of some of the most interesting recent advances.

  17. Positron Physics

    NASA Technical Reports Server (NTRS)

    Drachman, Richard J.

    2003-01-01

    I will give a review of the history of low-energy positron physics, experimental and theoretical, concentrating on the type of work pioneered by John Humberston and the positronics group at University College. This subject became a legitimate subfield of atomic physics under the enthusiastic direction of the late Sir Harrie Massey, and it attracted a diverse following throughout the world. At first purely theoretical, the subject has now expanded to include high brightness beams of low-energy positrons, positronium beams, and, lately, experiments involving anti-hydrogen atoms. The theory requires a certain type of persistence in its practitioners, as well as an eagerness to try new mathematical and numerical techniques. I will conclude with a short summary of some of the most interesting recent advances.

  18. The Prospects for High-Yield ICF with a Z-Pinch Driven Dynamic Hohlraum

    SciTech Connect

    CHANDLER, GORDON A.; CHRIEN, R.; COOPER, GARY WAYNE; DERZON, MARK S.; DOUGLAS, MELISSA R.; HEBRON, DAVID E.; LASH, JOEL S.; LEEPER, RAMON J.; MATZEN, M. KEITH; MEHLHORN, THOMAS A.; NASH, THOMAS J.; OLSON, RICHARD E.; PETERSON, D.L.; RUIZ, CARLOS L.; SANFORD, THOMAS W. L.; SLUTZ, STEPHEN A.

    1999-09-07

    Recent success with the Sandia Z machine has renewed interest in utilizing fast z-pinenes for ICF. One promising concept places the ICF capsule internal to the imploding z-pinch. At machine parameters relevant to achieving high yield, the imploding z-pinch mass has sufficient opacity to trap radiation giving rise to a dynamic hohlraum. The concept utilizes a 12 MJ, 54 MA z-pinch driver producing a capsule drive temperature exceeding 300 eV to realize a 550 MJ thermonuclear yield. They present the current high-yield design and its development that supports high-yield ICF with a z-pinch driven dynamic hohlraum.

  19. Dusty Starbursts within a z=3 Large Scale Structure revealed by ALMA

    NASA Astrophysics Data System (ADS)

    Umehata, Hideki

    The role of the large-scale structure is one of the most important theme in studying galaxy formation and evolution. However, it has been still mystery especially at z>2. On the basis of our ALMA 1.1 mm observations in a z ~ 3 protocluster field, it is suggested that submillimeter galaxies (SMGs) preferentially reside in the densest environment at z ~ 3. Furthermore we find a rich cluster of AGN-host SMGs at the core of the protocluster, combining with Chandra X-ray data. Our results indicate the vigorous star-formation and accelerated super massive black hole (SMBH) growth in the node of the cosmic web.

  20. Precise QCD Predictions for the Production of a Z Boson in Association with a Hadronic Jet.

    PubMed

    Gehrmann-De Ridder, A; Gehrmann, T; Glover, E W N; Huss, A; Morgan, T A

    2016-07-08

    We compute the cross section and differential distributions for the production of a Z boson in association with a hadronic jet to next-to-next-to-leading order (NNLO) in perturbative QCD, including the leptonic decay of the Z boson. We present numerical results for the transverse momentum and rapidity distributions of both the Z boson and the associated jet at the LHC. We find that the NNLO corrections increase the NLO predictions by approximately 1% and significantly reduce the scale variation uncertainty.