Science.gov

Sample records for accelerator-based atomic physics

  1. Fifty years of accelerator based physics at Chalk River

    SciTech Connect

    McKay, John W.

    1999-04-26

    The Chalk River Laboratories of Atomic Energy of Canada Ltd. was a major centre for Accelerator based physics for the last fifty years. As early as 1946, nuclear structure studies were started on Cockroft-Walton accelerators. A series of accelerators followed, including the world's first Tandem, and the MP Tandem, Superconducting Cyclotron (TASCC) facility that was opened in 1986. The nuclear physics program was shut down in 1996. This paper will describe some of the highlights of the accelerators and the research of the laboratory.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  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. Four Weeks of Atomic Physics.

    ERIC Educational Resources Information Center

    Lo Presto, Michael C.

    1995-01-01

    Describes a strategy for presenting ideas of atomic physics in the laboratory portion of the course before it is introduced during a lecture in order to give students an appreciation for the concepts involved, a historical look at how the field developed, and a comprehensive review of physics concepts. Presents a worksheet for the Bohr atom…

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Accelerator-based BNCT.

    PubMed

    Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

    2014-06-01

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases. PMID:24365468

  14. Guide to Laboratory Practicum in Atomic Physics

    NASA Astrophysics Data System (ADS)

    Burbulea, N. F.; Golban, G. N.; Scurtul, V. V.; Oleynik, V. A.

    1980-12-01

    The broshure represents a collection of 11 Laboratory works in Quantum Optics, Semiconductor, Atomic and Nuclear Physics for students of 2-nd years from Technical High Schools. A minimum of theoretical knowledges is given as well as a description of experimental installation (setup),a number of control questions and a task to be carried out is presented for every of the Laboratory work.

  15. 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.

  16. The ALADDIN atomic physics database system

    SciTech Connect

    Hulse, R.A. )

    1990-05-01

    ALADDIN is an atomic physics database system which has been developed in order to provide a broadly-based standard medium for the exchange and management of atomic data. ALADDIN consists of a data format definition together with supporting software for both interactive searches as well as for access to the data by plasma modeling and other codes. 8AB The ALADDIN system is designed to offer maximum flexibility in the choice of data representations and labeling schemes, so as to support a wide range of atomic physics data types and allow natural evolution and modification of the database as needs change. Associated dictionary files are included in the ALADDIN system for data documentation. The importance of supporting the widest possible user community was also central to be ALADDIN design, leading to the use of straightforward text files with concatentated data entries for the file structure, and the adoption of strict FORTRAN 77 code for the supporting software. This will allow ready access to the ALADDIN system on the widest range of scientific computers, and easy interfacing with FORTRAN modeling codes, user developed atomic physics codes and database, etc. This supporting software consists of the ALADDIN interactive searching and data display code, together with the ALPACK subroutine package which provides ALADDIN datafile searching and data retrieval capabilities to user's codes.

  17. Efimov physics in {sup 6}Li atoms

    SciTech Connect

    Braaten, Eric; Hammer, H.-W.; Kang, Daekyoung; Platter, Lucas

    2010-01-15

    A new narrow three-atom loss resonance associated with an Efimov trimer crossing the three-atom threshold has recently been discovered in a many-body system of ultracold {sup 6}Li atoms in the three lowest hyperfine spin states at a magnetic field near 895 G. O'Hara and coworkers have used measurements of the three-body recombination rate in this region to determine the complex three-body parameter associated with Efimov physics. Using this parameter as the input, we calculate the universal predictions for the spectrum of Efimov states and for the three-body recombination rate in the universal region above 600 G where all three scattering lengths are large. We predict an atom-dimer loss resonance at 672+-2 G associated with an Efimov trimer disappearing through an atom-dimer threshold. We also predict an interference minimum in the three-body recombination rate at 759+-1 G where the three-spin mixture may be sufficiently stable to allow experimental study of the many-body system.

  18. Atomic Physics 15: Proceedings of the Fifteenth International Conference on Atomic Physics.

    NASA Astrophysics Data System (ADS)

    van Linden van den Heuvell, H. B.; Walraven, J. T. M.; Reynolds, M. W.

    1997-07-01

    The Table of Contents for the full book PDF is as follows: * Preface * Generation of a "Schrödinger cat" of radiation and observation of its decoherence * Synthesis of entangled states and quantum computing * Entangled states of atomic ions for quantum metrology and computation * Entanglement and indistinguishability: Coherence experiments with photon pairs and triplets * Atom optics as a testing ground for quantum chaos * Coherent ultra-bright XUV lasers and harmonics * Hollow atoms * Interdisciplinary experiments with polarized noble gases * The creation and study of Bose-Einstein condensation in a cold alkali vapor * oscopic quantum phenomena in trapped Bose-condensed gases * Doppler-free spectroscopy of trapped atomic hydrogen * QED and the ground state of helium * Towards coherent atomic samples using laser cooling * Bose-Einstein condensation of a weakly-interacting gas * Zeeman and his contemporaries: Dutch physics around 1900 * Zeeman's great discovery * The Zeeman effect: A tool for atom manipulation * The Zeeman effect a century later: New insights into classical physics * QED effects in few-electron high-Z systems * Lamb shift experiments on high-Z one- and two-electron systems * Fundamental constants of nature * Response of atoms in photonic lattices * Hydrogen-like systems and quantum electrodynamics * New experiments with atomic lattices bound by light * Bloch oscillations of atoms in an optical potential * Quantum decoherence and inertial sensing with atom interferometers * Quantum effects in He clusters * Atoms in super-intense radiation fields * Wave packet dynamics of excited atomic electrons in intense laser fields * Nonlinear laser-electron scattering * Comparing the antiproton and proton and progress toward cold antihydrogen * Author Index

  19. 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.

  20. 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.

  1. 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.

  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. Intense coherent terahertz generation from accelerator-based sources

    NASA Astrophysics Data System (ADS)

    Hama, Hiroyuki; Yasuda, Mafuyu; Kawai, Masayuki; Hinode, Fujio; Nanbu, Kenichi; Miyahara, Fusashi

    2011-05-01

    The development of terahertz (THz) technology and science relevant to accelerator-based sources has been rapid, based on laser and semiconductor physics. To assure further progress of this scientific field, extremely intense radiation, involving gigawatt-class peak power, is needed. In addition to discussing the prospects for typical accelerator-based THz sources, such as coherent synchrotron radiation (CSR) and free electron lasers (FELs), novel, advanced THz sources employing isochronous-ring and bunched-FEL approaches are proposed.

  4. 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

  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. 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…

  7. 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

  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. Tight Binding Models in Cold Atoms Physics

    NASA Astrophysics Data System (ADS)

    Zakrzewski, J.

    2007-05-01

    Cold atomic gases placed in optical lattice potentials offer a unique tool to study simple tight binding models. Both the standard cases known from the condensed matter theory as well as novel situations may be addressed. Cold atoms setting allows for a precise control of parameters of the systems discussed, stimulating new questions and problems. The attempts to treat disorder in a controlled fashion are addressed in detail.

  10. The physics of spin polarized atomic vapors

    NASA Astrophysics Data System (ADS)

    Happer, William

    1988-05-01

    Research efforts are focussed on the study of spin polarized atoms, nuclei and electrons during the period covered by this report. Although this work is 6.1 basic research, it has applications to a number of important Air Force problems. For example, the atomic clocks used on the GPS satellite system operate with optically pumped rubidium absorption cells, very similar to the ones being investigated here. A number of the scientists and engineers working on atomic clocks used by Air Force satellite systems were trained with the support of this grant. We have participated in recent Air Force advisory panels to review concepts for high-energy-density fuels based on spin polarized atoms and molecules. The insights gained from research sponsored by this grant have been very useful in evaluating these ideas. Recent work has focussed on two main areas, the investigation of quadrupolar interactions between spin polarized noble gas nuclei and surfaces and the quantitative investigation of how magnetic field inhomogeneities cause spin relaxation.

  11. 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.

  12. Accelerator-based Experiments For Introductory-level Undergraduates

    SciTech Connect

    Sanders, Justin M.

    2009-03-10

    Although accelerator based experiments for undergraduates are often considered only for junior or senior physics majors, introductory students can also benefit from them. Rutherford backscattering and a {sup 12}C(p,p){sup 12}C elastic scattering resonance can be presented in ways that are well-suited for students who have taken only an introductory physics course.

  13. Experimental atomic physics in heavy-ion storage rings

    SciTech Connect

    Datz, S.; Andersen, L.H.; Briand, J.P.; Liesen, D.

    1987-01-01

    This paper outlines the discussion which took place at the ''round table'' on experimental atomic physics in heavy-ion storage rings. Areas of discussion are: electron-ion interactions, ion-ion collisions, precision spectroscopy of highly charged ions, beta decay into bound final states, and atomic binding energies from spectroscopy of conversion elections. 18 refs., 1 tab. (LSP)

  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. Applications of atomic and molecular data to radiation physics

    SciTech Connect

    Inokuti, M.

    1982-01-01

    The general purpose of our work is to provide atomic and molecular collision cross sections useful for radiological physics, dosimetry, and other applications. Studies on the systematics of atomic oscillator-strength spectra and a survey of stopping power data are briefly described. (WHK)

  16. 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,…

  17. 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.

  18. New results in atomic physics at the Advanced Light Source

    SciTech Connect

    Schlachter, A.S.

    1995-01-01

    The Advanced Light Source is the world's first low-energy third-generation synchrotron radiation source. It has been running reliably and exceeding design specifications since it began operation in October 1993. It is available to a wide community of researchers in many scientific fields, including atomic and molecular science and chemistry. Here, new results in atomic physics at the Advanced Light Source demonstrate the opportunities available in atomic and molecular physics at this synchrotron light source. The unprecedented brightness allows experiments with high flux, high spectral resolution, and nearly 100% linear polarization.

  19. Alkali--rare gas photodissociation lasers: Applications to laser physics and atom-atom interactions

    NASA Astrophysics Data System (ADS)

    Hewitt, John Darby

    This dissertation describes several experiments in which alkali--rare gas laser systems are utilized as a simple platform with which to isolate and study atom-atom interactions and fundamental physical processes that are ill-understood or have never been investigated previously. Specifically, the minimum allowable energy separation between levels 2 and 3 in a three-level laser system has been investigated experimentally, as have two-photon absorption processes in atomic Rb and Cs.

  20. SOHO: Atomic physics and the solar atmosphere

    SciTech Connect

    Kucera, T. A.

    1998-09-28

    Many aspects of the Sun's corona and wind are studied using data from the ultraviolet spectrum. Accurate atomic parameters are needed to interpret these data correctly, and a good understanding of the behaviors of atoms and ions in plasmas is essential to modeling the Sun's atmosphere. Here I present two examples of studies being carried out using the Solar and Heliospheric Observatory (SOHO) extreme ultraviolet spectrographs. The first of these is the study of flows in the Sun's chromosphere and corona. SOHO has provided new information concerning previous observations of the predominant down-flows in the Sun's lower atmosphere. Accurate measurements of Doppler line shifts have been extended to the corona. It has also been found that the Doppler shifts vary over different parts of the Sun. The second study discussed involves the use of SOHO data to measure elemental abundances in coronal structures know as streamers, giving more information on the 'FIP' effect--the observation that there is a relative deficit of elements with high first ionization potentials (FIPs) in the corona and solar wind.

  1. Physics Division progress report for period ending September 30, 1983

    SciTech Connect

    Not Available

    1983-12-01

    Research and development activities are summarized in the following areas: Holifield Heavy Ion Research Facility, nuclear physics, the UNISOR program, accelerator-based atomic physics, theoretical physics, nuclear science applications, atomic physics and plasma diagnostics for fusion program, high-energy physics, the nuclear data project, and the relativistic heavy-ion collider study. Publications and papers presented are listed. (WHK)

  2. 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.

  3. 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.

  4. Subpanel on accelerator-based neutrino oscillation experiments

    SciTech Connect

    1995-09-01

    Neutrinos are among nature`s fundamental constituents, and they are also the ones about which we know least. Their role in the universe is widespread, ranging from the radioactive decay of a single atom to the explosions of supernovae and the formation of ordinary matter. Neutrinos might exhibit a striking property that has not yet been observed. Like the back-and-forth swing of a pendulum, neutrinos can oscillate to-and-from among their three types (or flavors) if nature provides certain conditions. These conditions include neutrinos having mass and a property called {open_quotes}mixing.{close_quotes} The phenomenon is referred to as neutrino oscillations. The questions of the origin of neutrino mass and mixing among the neutrino flavors are unsolved problems for which the Standard Model of particle physics holds few clues. It is likely that the next critical step in answering these questions will result from the experimental observation of neutrino oscillations. The High Energy Physics Advisory Panel (HEPAP) Subpanel on Accelerator-Based Neutrino Oscillation Experiments was charged to review the status and discovery potential of ongoing and proposed accelerator experiments on neutrino oscillations, to evaluate the opportunities for the U.S. in this area of physics, and to recommend a cost-effective plan for pursuing this physics, as appropriate. The complete charge is provided in Appendix A. The Subpanel studied these issues over several months and reviewed all the relevant and available information on the subject. In particular, the Subpanel reviewed the two proposed neutrino oscillation programs at Fermi National Accelerator Laboratory (Fermilab) and at Brookhaven National Laboratory (BNL). The conclusions of this review are enumerated in detail in Chapter 7 of this report. The recommendations given in Chapter 7 are also reproduced in this summary.

  5. 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.

  6. HISTRAP proposal: heavy ion storage ring for atomic physics

    SciTech Connect

    Olsen, D.K.; Alton, G.D.; Datz, S.; Dittner, P.F.; Dowling, D.T.; Haynes, D.L.; Hudson, E.D.; Johnson, J.W.; Lee, I.Y.; Lord, R.S.

    1986-11-01

    HISTRAP, Heavy Ion Storage Ring for Atomic Physics, is a proposed 46.8-m-circumference synchrotron-cooling-storage ring optimized to accelerate, decelerate, and store beams of highly charged very-heavy ions at energies appropriate for advanced atomic physics research. The ring is designed to allow studies of electron-ion, photon-ion, ion-atom, and ion-ion interactions. An electron cooling system will provide ion beams with small angular divergence and energy spread for precision spectroscopic studies and also is necessary to allow the deceleration of heavy ions to low energies. HISTRAP will have a maximum bending power of 2.0 Tm and will be injected with ions from either the existing Holifield Heavy Ion Research Facility 25-MV tandem accelerator or from a dedicated ECR source and 250 keV/nucleon RFQ linac.

  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. 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.

  10. 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,…

  11. 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.

  12. Atomic physics experiments at the high energy storage ring

    NASA Astrophysics Data System (ADS)

    Stöhlker, Thomas; Litvinov, Yuri A.; the SPARC Collaboration

    2015-11-01

    Facility for Antiproton and Ion Research (FAIR), will offer unprecedented experimental opportunities. The Stored Particles Atomic Research Collaboration (SPARC) at FAIR aims at creating a worldwide unique research program with highly charged ions by utilizing storage ring and trapping facilities. The foreseen experiments will address physics at strong, ultra-short electromagnetic fields including the fundamental interactions between electrons and heavy nuclei as well as the experiments at the border between nuclear and atomic physics. In view of the staged construction of the FAIR facility, SPARC worked out an early realization scheme for experiments with highly-charged heavy-ions at relativistic energies to be conducted in the High-Energy Storage Ring.

  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. 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.

  15. Polarized noble-gas atoms: A tool for fundamental physics

    SciTech Connect

    Chupp, T.E.

    1993-05-01

    Polarized noble gas atom samples suitable for a variety of experiments can be produced by spin exchange with laser optically pumped alkali-metal vapors. Most stable and even radioactive isotopes of He, Ne, Kr, Xe and Rn have been polarized, and the field has been paced, in part by laser developments and study of the atomic collision processes. I will focus on two kinds of application: (1) precision measurement of free precession frequencies to probe fundamental concepts such as CP violation, Local Lorentz Invariance and Linearity in Quantum Mechanics; (2) a polarized {sup 3}He target for electron scattering to extract information on the structure of the neutron. The precision measurement techniques take advantage of long coherence times (measured in hours for {sup 3}He and {sup 21}Ne) and large signal to noise ratios to measure frequency shifts with precision 10{sup -7} Hz in one hour. The polarized {sup 3}He target is used to measure asymmetries in deep inelastic electron scattering which are dominated by the neutron since the proton spins are approximately paired in the ground state of the nucleus. The spin dependent structure function of the neutron is an essential probe of the quark-parton structure of the nucleon. All of these investigations combine fundamental and particle physics motivation with atomic physics and precision measurement techniques in a way that spans many subfields of physics.

  16. Efimov physics in atom-dimer scattering of {sup 6}Li atoms

    SciTech Connect

    Hammer, H.-W.; Kang, Daekyoung; Platter, Lucas

    2010-08-15

    {sup 6}Li atoms in the three lowest hyperfine states display universal properties when the S-wave scattering length between each pair of states is large. Recent experiments reported four pronounced features arising from Efimov physics in the atom-dimer relaxation rate, namely two resonances and two local minima. We use the universal effective-field theory to calculate the atom-dimer relaxation rate at zero temperature. Our results describe the four features qualitatively and imply there is a hidden local minimum. In the vicinity of the resonance at 685 G, we perform a finite temperature calculation which improves the agreement of theory and experiment. We conclude that finite temperature effects cannot be neglected in the analysis of the experimental data.

  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. HISTRAP proposal: heavy ion storage ring for atomic physics

    SciTech Connect

    Olsen, D.K.; Alton, G.D.; Datz, S.; Dittner, P.F.; Dowling, D.T.; Haynes, D.L.; Hudson, E.D.; Johnson, J.W.; Lee, I.Y.; Lord, R.S.

    1986-01-01

    HISTRAP is a proposed synchrotron-cooling-storage ring optimized to accelerate, decelerate, and store beams of highly charged very-heavy ions at energies appropriate for advanced atomic physics research. The ring is designed to allow studies of electron-ion, photon-ion, ion-atom, and ion-ion interactions. An electron cooling system will provide ion beams with small angular divergence and energy spread for precision spectroscopic studies and also is necessary to allow the deceleration of heavy ions to low energies. HISTRAP will be injected with ions from either the existing Holifield Heavy Ion Research Facility 25-MV tandem accelerator or from a dedicated ECR source and 250 keV/nucleon RFQ linac. The ring will have a maximum bending power of 2.0 T.m and have a circumference of 46.8 m.

  19. Atomic physics effects on dissipative toroidal drift wave stability

    SciTech Connect

    Beer, M.A.; Hahm, T.S.

    1992-02-01

    The effects of atomic physics processes such as ionization, charge exchange, and radiation on the linear stability of dissipative drift waves are investigated in toroidal geometry both numerically and analytically. For typical TFTR and TEXT edge parameters, overall linear stability is determined by the competition between the destabilizing influence of ionization and the stabilizing effect due to the electron temperature gradient. An analytical expression for the linear marginal stability condition, {eta}{sub e}{sup crit}, is derived. The instability is most likely to occur at the extreme edge of tokamaks with a significant ionization source and a steep electron density gradient.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Atomic Physics with Accelerators: Projectile Electron Spectroscopy (APAPES)

    NASA Astrophysics Data System (ADS)

    Madesis, I.; Dimitriou, A.; Laoutaris, A.; Lagoyannis, A.; Axiotis, M.; Mertzimekis, T.; Andrianis, M.; Harissopulos, S.; Benis, E. P.; Sulik, B.; Valastyán, I.; Zouros, T. J. M.

    2015-01-01

    The new research initiative APAPES (http://apapes.physics.uoc.gr/) has already established a new experimental station with a beam line dedicated for atomic collisions physics research, at the 5 MV TANDEM accelerator of the National Research Centre "Demokritos" in Athens, Greece. A complete zero-degree Auger projectile spectroscopy (ZAPS) apparatus has been put together to perform high resolution studies of electrons emitted in ion-atom collisions. A single stage hemispherical spectrometer with a 2-dimensional Position Sensitive Detector (PSD) combined with a doubly-differentially pumped gas target will be used to perform a systematic isoelectronic investigation of K-Auger spectra emitted from collisions of preexcited and ground state He-like ions with gas targets using novel techniques. Our intention is to provide a more thorough understanding of cascade feeding of the 1s2s2p 4P metastable states produced by electron capture in collisions of He-like ions with gas targets and further elucidate their role in the non-statistical production of excited three-electron 1s2s2p states by electron capture, recently a field of conflicting interpretations awaiting further resolution. At the moment, the apparatus is being completed and the spectrometer will soon be fully operational. Here we present the project progress and the recent high resolution spectrum obtained in collisions of 12 MeV C4+ on a Neon gas target.

  5. 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.

  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. 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.

  9. The Collective Vector method in nuclear and atomic physics

    SciTech Connect

    Bloom, S.D.

    1989-12-01

    We present a brief review of the method of the Collective Vector (CV) and its use in conjunction with the Lanczos algorithm (LA). The combination of these two ideas produces a method for contracting super-large hamiltonians (up to 10{sup 6} {times} 10{sup 6}) by factors of 1000 or more. The contracted hamiltonians, which we call quasi-hamiltonians, typically have dimensions of the order of 10{sup 2} {times} 10{sup 2} and produce corresponding quasi-spectra with associated quasi-eigenfunctions which reproduce the features of the full microscopic spectrum thru the conservation of the spectral moments. Examples of applications to both nuclear and atomic physics are given demonstrating the convergence properties of the method. The application of the LA/CV approach to the problem of modelling nuclear level densities is described and finally we discuss the possibility of conjoining new collective models of nuclear structure with the LA/CV method. 13 refs., 4 figs.

  10. 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.

  11. 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.

  12. 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.

  13. The Los Alamos suite of relativistic atomic physics codes

    DOE PAGESBeta

    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 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

  14. 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

  15. I.I. Rabi Prize in Atomic, Molecular and Optical Physics Talk: Novel Quantum Physics in Few- and Many-body Atomic Systems

    NASA Astrophysics Data System (ADS)

    Chin, Cheng

    2011-05-01

    Recent cold atom researches are reaching out far beyond the realm that was conventionally viewed as atomic physics. Many long standing issues in other physics disciplines or in Gedanken-experiments are nowadays common targets of cold atom physicists. Two prominent examples will be discussed in this talk: BEC-BCS crossover and Efimov physics. Here, cold atoms are employed to emulate electrons in superconductors, and nucleons in nuclear reactions, respectively. The ability to emulate exotic or thought systems using cold atoms stems from the precisely determined, simple, and tunable interaction properties of cold atoms. New experimental tools have also been devised toward an ultimate goal: a complete control and a complete characterization of a few- or many-body quantum system. We are tantalizingly close to this major milestone, and will soon open new venues to explore new quantum phenomena that may (or may not!) exist in scientists' dreams.

  16. The SPARC linear accelerator based terahertz source

    SciTech Connect

    Chiadroni, E.; Bacci, A.; Bellaveglia, M.; Boscolo, M.; Castellano, M.; Cultrera, L.; Di Pirro, G.; Ferrario, M.; Ficcadenti, L.; Filippetto, D.; Gatti, G.; Pace, E.; Rossi, A. R.; Vaccarezza, C.; Catani, L.; Cianchi, A.; Marchetti, B.; Mostacci, A.; Palumbo, L.; Ronsivalle, C.; and others

    2013-03-04

    Ultra-short electron beams, produced through the velocity bunching compression technique, are used to drive the SPARC linear accelerator based source, which relies on the emission of coherent transition radiation in the terahertz range. This paper reports on the main features of this radiation, as terahertz source, with spectral coverage up to 5 THz and pulse duration down to 200 fs, with an energy per pulse of the order of several micro-joule, and as electron beam longitudinal diagnostics.

  17. Precision atomic mass spectrometry with applications to fundamental constants, neutrino physics, and physical chemistry

    NASA Astrophysics Data System (ADS)

    Mount, Brianna J.; Redshaw, Matthew; Myers, Edmund G.

    2011-07-01

    We present a summary of precision atomic mass measurements of stable isotopes carried out at Florida State University. These include the alkalis 6Li, 23Na, 39,41K, 85,87Rb, 133Cs; the rare gas isotopes 84,86Kr and 129,130,132,136Xe; 17,18O, 19F, 28Si, 31P, 32S; and various isotope pairs of importance to neutrino physics, namely 74,76Se/74,76Ge, 130Xe/130Te, and 115In/115Sn. We also summarize our Penning trap measurements of the dipole moments of PH + and HCO + .

  18. Accelerator-based neutrino oscillation experiments

    SciTech Connect

    Harris, Deborah A.; /Fermilab

    2007-12-01

    Neutrino oscillations were first discovered by experiments looking at neutrinos coming from extra-terrestrial sources, namely the sun and the atmosphere, but we will be depending on earth-based sources to take many of the next steps in this field. This article describes what has been learned so far from accelerator-based neutrino oscillation experiments, and then describe very generally what the next accelerator-based steps are. In section 2 the article discusses how one uses an accelerator to make a neutrino beam, in particular, one made from decays in flight of charged pions. There are several different neutrino detection methods currently in use, or under development. In section 3 these are presented, with a description of the general concept, an example of such a detector, and then a brief discussion of the outstanding issues associated with this detection technique. Finally, section 4 describes how the measurements of oscillation probabilities are made. This includes a description of the near detector technique and how it can be used to make the most precise measurements of neutrino oscillations.

  19. Benchmarking atomic physics models for magnetically confined fusion plasma physics experiments

    NASA Astrophysics Data System (ADS)

    May, M. J.; Finkenthal, M.; Soukhanovskii, V.; Stutman, D.; Moos, H. W.; Pacella, D.; Mazzitelli, G.; Fournier, K.; Goldstein, W.; Gregory, B.

    1999-01-01

    In present magnetically confined fusion devices, high and intermediate Z impurities are either puffed into the plasma for divertor radiative cooling experiments or are sputtered from the high Z plasma facing armor. The beneficial cooling of the edge as well as the detrimental radiative losses from the core of these impurities can be properly understood only if the atomic physics used in the modeling of the cooling curves is very accurate. To this end, a comprehensive experimental and theoretical analysis of some relevant impurities is undertaken. Gases (Ne, Ar, Kr, and Xe) are puffed and nongases are introduced through laser ablation into the FTU tokamak plasma. The charge state distributions and total density of these impurities are determined from spatial scans of several photometrically calibrated vacuum ultraviolet and x-ray spectrographs (3-1600 Å), the multiple ionization state transport code transport code (MIST) and a collisional radiative model. The radiative power losses are measured with bolometery, and the emissivity profiles were measured by a visible bremsstrahlung array. The ionization balance, excitation physics, and the radiative cooling curves are computed from the Hebrew University Lawrence Livermore atomic code (HULLAC) and are benchmarked by these experiments. (Supported by U.S. DOE Grant No. DE-FG02-86ER53214 at JHU and Contract No. W-7405-ENG-48 at LLNL.)

  20. Design, fabrication and characterization of tunable external cavity diode laser and atom trapping chips for atomic physics

    NASA Astrophysics Data System (ADS)

    Chuang, Ho-Chiao

    External cavity diode laser systems (ECDLs) have been well documented for their suitability in the fields of laser cooling and atom trapping, and are now widely used in optical and atomic physics. A particularly simple implementation of this idea uses feedback from a diffraction grating mounted in the Littrow configuration and the typical size of this laser is quite large (120mmx90mmx90mm). For atom optics, the current atom trapping chips are not in a feedthrough configuration, which makes the chips to glass cell assembly process complicated and the wires and solder areas vulnerable, resulting in an unreliable vacuum seal. Recent experimental realizations of atom optical devices such as atomic waveguides, beam splitters, and on-chip Bose-Einstein condensate (BEC) sources have opened a new field for the development of more complex devices such as, e.g., BEC-based atom transistor. This work focuses on micro/nano fabrication techniques to build three different devices for the miniature BEC system. The research work focuses on the development of new ECDLs, a novel fabrication process of feedthrough atom trapping chips for atomic optics and a fabrication process for atom transistor chips. In the ECDLs part, we describe a new method for constructing a smaller external-cavity diode laser by use of a micromachined silicon flexure and a VHG (Volume Holographic Grating). It is much smaller, inexpensive and easy to build because it is based on simple modifications of a few commercial optical and mechanical components but with a specific silicon flexure design enabled by micro-fabrication technology for the laser frequency tuning. In the feedthrough chips part, we present a novel fabrication process for feedthrough atom trapping chips in atomic condensate optics cells using the copper electroplating to seal the vias. The advantages of using feedthrough atom trapping chips are the simple microfabrication process and reduction of the overall chip area bonded on the glass atom

  1. Pre-service physics teachers' ideas on size, visibility and structure of the atom

    NASA Astrophysics Data System (ADS)

    Ünlü, Pervin

    2010-07-01

    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 theories regarding the atom they will bring into their own classrooms. Six tasks were developed, comprising size, visibility and structure of the atom. These tasks carried out by pre-service physics teachers were examined by content analysis and six categories were determined. These are size, visibility, subatomic particles, atom models, electron orbit and electron features. Pre-service physics teachers' ideas about the atom were clarified under these categories.

  2. Many-body processes in atomic and molecular physics

    SciTech Connect

    Chu, Shih-I.

    1990-02-01

    This report discusses the following topics: Dynamics of Multiphoton Excitation in Rydberg Atoms; Nonlinear Schrodinger Equation and Dissipative Quantum Dynamics in Periodic Fields; Density Matrix Formulation of Complex Geometric Phases in Dissipative Systems; and A. C. Stark Shifts of Excited States of Atoms in Strong Fields.

  3. Studying Atomic Physics Using the Nighttime Atmosphere as a Laboratory

    NASA Technical Reports Server (NTRS)

    Sharpee, B. D.; Slanger, T. G.; Huestis, D. L.; Cosby, P. C.

    2006-01-01

    A summary of our recent work using terrestrial nightglow spectra, obtained from astronomical instrumentation, to directly measure, or evaluate theoretical values for fundamental parameters of astrophysically important atomic lines.

  4. Current Topics in Atomic, Molecular and Optical Physics

    NASA Astrophysics Data System (ADS)

    Sinha, Chandana; Bhattacharyya, Shib Shankar

    Preface -- Ultrafast dynamics of nano and mesoscopic systems driven by asymmetric electromagnetic pulses / A. Matos-Abiague, A. S. Moskalenko and J. Berakdar -- One-dimensional non-linear oscillators as models for atoms and molecules under intense laser fields / A. Wadehra and B. M. Deb -- Experimenting with topological states of Bose-Einstein condensates / C. Raman -- Laser cooling and trapping of Rb atoms / S. Chakraborty ... [et al.] -- Pair-correlation in Bose-Einstein condensate and fermi superfluid of atomic gases / B. Deb -- Properties of trapped Bose gas in the large-gas-parameter regime / A. Banerjee -- A Feynman-Kac path integral study of Rb gas / S. Datta -- Mean field theory for interacting spin-1 bosons on a lattice / R. V. Pai, K. Sheshadri and R. Pandit -- Mixed internal-external state approach for quantum computation with neutral atoms on atom chips / E. Charron ... [et al.] -- Ultrafast pulse shaping developments for quantum computation / S. K. Karthick Kumar and D. Goswami -- Quantum information transfer in atom-photon interactions in a cavity / A. S. Majumdar, N. Nayak and B. Ghosh -- Liouville density evolution in billiards and the quantum connection / D. Biswas -- MRCPA: theory and application to highly correlating system / K. Tanaka -- Calculation of negative ion shape resonances using coupled cluster theory / Y. Sajeev and S. Pal -- Optical frequency standard with Sr+: a theoretical many-body approach / C. Sur ... [et al.] -- Fast heavy ion collisions with H[symbol] molecules and young type interference / L. C. Tribedi and D. Misra -- Estimation of ion kinetic energies from time-of-flight and momentum spectra / B. Bapat -- Third-order optical susceptibility of metal nanocluster-glass 28 composites / B. Ghosh and P. Chakraborty -- Study of atom-surface interaction using magnetic atom mirror / A. K. Mohapatra.

  5. 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…

  6. First experiments on neutron detection on the accelerator-based source for boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. S.; Malyshkin, G. N.; Makarov, A. N.; Sorokin, I. N.; Sulyaev, Yu. S.; Taskaev, S. Yu.

    2009-04-01

    A pilot accelerator-based source of epithermal neutrons, which is intended for wide application in clinics for boron neutron capture therapy, has been constructed at the Budker Institute of Nuclear Physics (Novosibirsk). A stationary proton beam has been obtained and near-threshold neutron generation regime has been realized. Results of the first experiments on neutron generation using the proposed source are described.

  7. From Casimir-Polder Force to Dicke Physics: Interaction between Atoms and a Topological Insulator

    NASA Astrophysics Data System (ADS)

    Fuchs, Sebastian; Buhmann, Stefan

    We apply the theory of macroscopic quantum electrodynamics in dispersing and absorbing media to study the Casimir-Polder force between an atom and a topological insulator. The electromagnetic response of a topological insulator surface leads to a mixing of electric and magnetic fields, breaking the time-reversal symmetry. The coupling of these fields to an atom causes shifts of the atom's eigenenergies and modified decay rates near the surface of the topological insulator. Energy shifts and modified decay rates cannot only be triggered by the presence of a material, but can be caused by other atoms in close proximity as well. The collective dynamics of atoms (Dicke Physics) leads to a superradiant burst. Combining macroscopic QED and Dicke physics opens the door to the investigation of cooperative atom-surface interactions.

  8. 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…

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Atomic and molecular physics in the gas phase

    SciTech Connect

    Toburen, L.H.

    1990-09-01

    The spatial and temporal distributions of energy deposition by high-linear-energy-transfer radiation play an important role in the subsequent chemical and biological processes leading to radiation damage. Because the spatial structures of energy deposition events are of the same dimensions as molecular structures in the mammalian cell, direct measurements of energy deposition distributions appropriate to radiation biology are infeasible. This has led to the development of models of energy transport based on a knowledge of atomic and molecular interactions process that enable one to simulate energy transfer on an atomic scale. Such models require a detailed understanding of the interactions of ions and electrons with biologically relevant material. During the past 20 years there has been a great deal of progress in our understanding of these interactions; much of it coming from studies in the gas phase. These studies provide information on the systematics of interaction cross sections leading to a knowledge of the regions of energy deposition where molecular and phase effects are important and that guide developments in appropriate theory. In this report studies of the doubly differential cross sections, crucial to the development of stochastic energy deposition calculations and track structure simulation, will be reviewed. Areas of understanding are discussed and directions for future work addressed. Particular attention is given to experimental and theoretical findings that have changed the traditional view of secondary electron production for charged particle interactions with atomic and molecular targets.

  14. 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)

  15. Atomic Parity Violation and Related Physics in Ytterbium

    NASA Astrophysics Data System (ADS)

    Dounas-Frazer, Dimitri Robert

    Atomic parity violation has been observed in the 408 nm 1 S0→3D1 forbidden transition of ytterbium. The parity violating amplitude is 8.7(1.4)e-10 ea0, two orders of magnitude larger than in cesium, where the most precise experiments to date have been performed. This is in accordance with theoretical predictions and constitutes the largest atomic parity violating amplitude yet observed. This also opens the way to future measurements of neutron skins and anapole moments by comparing parity-violating amplitudes for various isotopes and hyperfine components of the transition. We present a detailed description of the observation. Linearly polarized 408 nm light interacts with ytterbium atoms in crossed electric (E) and magnetic fields (B). The probability of the 1 S0→3D1 transition contains a parity-violating term, proportional to E'B[( E'xE B], arising from interference between the amplitudes of transitions induced by the electroweak interaction and the Stark effect ((E' is the optical electric field). The transition probability is detected by measuring the population of the metastable 3P0 state, to which 65% of the atoms excited to the 3D1 state spontaneously decay. The population of the 3P0 state is determined by resonantly exciting the atoms with 649 nm light to the 3S1 state and collecting the fluorescence resulting from its decay. Systematic corrections due to imperfections in the applied electric and magnetic fields are determined in auxiliary experiments. The statistical uncertainty is dominated by parasitic frequency excursions of the 408-nm excitation light due to imperfect stabilization of the optical reference with respect to the atomic resonance. The present uncertainties are 9% statistical and 8% systematic. Methods of improving the accuracy for the future experiments are discussed. We further present a measurement of the dynamic scalar and tensor polarizabilities of ytterbium's 3D1 state. The polarizabilities were measured by analyzing the spectral

  16. Plasma injection and atomic physics models for use in particle simulation codes

    SciTech Connect

    Procassini, R.J. California Univ., Berkeley, CA . Electronics Research Lab.)

    1991-06-12

    Models of plasma injection (creation) and charged/neutral atomic physics which are suitable for incorporation into particle simulation codes are described. Both planar and distributed source injection models are considered. Results obtained from planar injection into a collisionless plasma-sheath region are presented. The atomic physics package simulates the charge exchange and impact ionization interactions which occur between charged particles and neutral atoms in a partially-ionized plasma. These models are applicable to a wide range of problems, from plasma processing of materials to transport in the edge region of a tokamak plasma. 18 refs., 6 figs.

  17. Atomic physics techniques for studying nuclear ground state properties, fundamental interactions and symmetries: status and perspectives

    NASA Astrophysics Data System (ADS)

    Kluge, H.-Jürgen

    2010-02-01

    The international workshop on “Application of Lasers and Storage Devices in Atomic Nuclei Research” held during 2009 in Poznan gave an excellent overview on the latest experimental and theoretical results regarding the investigation of radionuclides by atomic physics techniques and the extraction of ground state properties of exotic nuclei. This publication intends to summarize the progress recently achieved by laser spectroscopy and mass spectrometry as well as by weak interaction studies using atomic physics techniques. Furthermore, it tries to point to some areas requiring urgent improvements and to indicate some routes of future research and challenging opportunities.

  18. Nuclear beta-decay, Atomic Parity Violation, and New Physics

    SciTech Connect

    Michael Ramsey-Musolf

    2000-08-01

    Determinations of vuds with super-allowed Fermi beta-decay in nuclei and of the weak charge of the cesium in atomic parity-violation deviate from the Standard Model predictions by 2 sigma or more. In both cases, the Standard Model over-predicts the magnitudes of the relevant observables. I discuss the implications of these results for R-parity violating (RPV) extensions of the minimal supersymmetric Standard Model. I also explore the possible consequences for RPV supersymmetry of prospective future low-energy electroweak measurements.

  19. A New Accelerator-Based Mass Spectrometry.

    ERIC Educational Resources Information Center

    Gove, H. E.

    1983-01-01

    Tandem electrostatic accelerators produce beams of positive ions which are used to penetrate atomic nuclei in a target, inducing nuclear reactions whose study elucidates varied properties of the nucleus. Uses of the system, which acts like a mass spectrometer, are discussed. These include radiocarbon dating measurements. (JN)

  20. Origin of the Universal Three-body Parameter in Atomic Efimov Physic

    NASA Astrophysics Data System (ADS)

    Naidon, Pascal; Endo, Shimpei; Ueda, Masahito

    2013-05-01

    Several experiments with different kinds of ultra-cold atoms have revealed that the three-body parameter that fixes the Efimov spectrum of few-atom systems near broad Feshbach resonances is universally determined by the atoms' van der Waals length. Using model potential calculations we find that the three-body parameter originates from a deformation of the three-atom system due to universal two-body correlations at separations on the order of the van der Waals length scale. This simple physical picture is consistent with the universality of the three-body parameter observed in the experiments, as well as previous numerical calculations. It explains why the low-energy physics of three bosonic atoms near a broad resonance is solely determined by their two-body parameters.

  1. 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…

  2. Physical state of interstellar atoms. [from Copernicus satellite UV data

    NASA Technical Reports Server (NTRS)

    York, D. G.

    1974-01-01

    Brief survey of the physical conditions along the lines of sight to reddened and unreddened stars, as determined from Copernicus observation of interstellar lines between 95 and 300 nm. Differences in ionization structure and density between clouds and the local intercloud medium are discussed. Some new data for beta Centauri is used to supplement the previously available data.

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

    PubMed

    Pederson, Thoru; Marko, John F

    2014-11-01

    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

  4. 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

  5. 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

  6. 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.

  7. Versatile single-chip event sequencer for atomic physics experiments

    NASA Astrophysics Data System (ADS)

    Eyler, Edward

    2010-03-01

    A very inexpensive dsPIC microcontroller with internal 32-bit counters is used to produce a flexible timing signal generator with up to 16 TTL-compatible digital outputs, with a time resolution and accuracy of 50 ns. This time resolution is easily sufficient for event sequencing in typical experiments involving cold atoms or laser spectroscopy. This single-chip device is capable of triggered operation and can also function as a sweeping delay generator. With one additional chip it can also concurrently produce accurately timed analog ramps, and another one-chip addition allows real-time control from an external computer. Compared to an FPGA-based digital pattern generator, this design is slower but simpler and more flexible, and it can be reprogrammed using ordinary `C' code without special knowledge. I will also describe the use of the same microcontroller with additional hardware to implement a digital lock-in amplifier and PID controller for laser locking, including a simple graphics-based control unit. This work is supported in part by the NSF.

  8. 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.

  9. 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.

  10. 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).

  11. Accurate abundance analysis of late-type stars: advances in atomic physics

    NASA Astrophysics Data System (ADS)

    Barklem, Paul S.

    2016-05-01

    The measurement of stellar properties such as chemical compositions, masses and ages, through stellar spectra, is a fundamental problem in astrophysics. Progress in the understanding, calculation and measurement of atomic properties and processes relevant to the high-accuracy analysis of F-, G-, and K-type stellar spectra is reviewed, with particular emphasis on abundance analysis. This includes fundamental atomic data such as energy levels, wavelengths, and transition probabilities, as well as processes of photoionisation, collisional broadening and inelastic collisions. A recurring theme throughout the review is the interplay between theoretical atomic physics, laboratory measurements, and astrophysical modelling, all of which contribute to our understanding of atoms and atomic processes, as well as to modelling stellar spectra.

  12. 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.

  13. Atomic physics at the future facility for antiproton and ion research: status report 2014

    NASA Astrophysics Data System (ADS)

    Gumberidze, A.; Stöhlker, Th; Litvinov, Yu A.; SPARC Collaboration

    2015-11-01

    In this contribution, a brief overview of the Stored Particle Atomic physics Research Collaboration scientific program at the upcoming Facility for Antiproton and Ion Research (FAIR) is given. The program comprises a very broad range of research topics addressing atomic structure and dynamics in hitherto unexplored regimes, light-matter interactions, lepton pair production phenomena, precision tests of quantum electrodynamics and standard model in the regime of extreme fields and many more. We also present the current strategy for the realization of the envisioned physics program within the modularized start version (MSV) of FAIR.

  14. 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

  15. Accelerator-based validation of shielding codes

    SciTech Connect

    Zeitlin, Cary; Heilbronn, Lawrence; Miller, Jack; Wilson, John W.

    2002-08-12

    The space radiation environment poses risks to astronaut health from a diverse set of sources, ranging from low-energy protons and electrons to highly-charged, high-energy atomic nuclei and their associated fragmentation products, including neutrons. The low-energy protons and electrons are the source of most of the radiation dose to Shuttle and ISS crews, while the more energetic particles that comprise the Galactic Cosmic Radiation (protons, He, and heavier nuclei up to Fe) will be the dominant source for crews on long-duration missions outside the earth's magnetic field. Because of this diversity of sources, a broad ground-based experimental effort is required to validate the transport and shielding calculations used to predict doses and dose-equivalents under various mission scenarios. The experimental program of the LBNL group, described here, focuses principally on measurements of charged particle and neutron production in high-energy heavy-ion fragmentation. Other aspects of the program include measurements of the shielding provided by candidate spacesuit materials against low-energy protons (particularly relevant to extra-vehicular activities in low-earth orbit), and the depth-dose relations in tissue for higher-energy protons. The heavy-ion experiments are performed at the Brookhaven National Laboratory's Alternating Gradient Synchrotron and the Heavy-Ion Medical Accelerator in Chiba in Japan. Proton experiments are performed at the Lawrence Berkeley National Laboratory's 88'' Cyclotron with a 55 MeV beam, and at the Loma Linda University Proton Facility with 100 to 250 MeV beam energies. The experimental results are an important component of the overall shielding program, as they allow for simple, well-controlled tests of the models developed to handle the more complex radiation environment in space.

  16. 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.

  17. 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…

  18. 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?’.

  19. Do general physics textbooks discuss scientists’ ideas about atomic structure? A case in Korea

    NASA Astrophysics Data System (ADS)

    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 physics textbooks often lack detail about the history and philosophy of science. This result is quite similar to those published for the USA. Furthermore, chemistry textbooks published in the USA, Turkey and Venezuela are quite similar to the physics textbooks. This is a cause for concern as textbooks present theories as facts and ignore the historical reconstructions based on the development of scientific theories that frequently involve controversies and conflicts among scientists. The inclusion of historical reconstructions of ideas about atomic structure can provide students with a better appreciation of the dynamics of scientific progress.

  20. Dosimetric comparison of linear accelerator-based stereotactic radiosurgery systems

    PubMed Central

    Sharma, S. D.; Kumar, Sudhir; Dagaonkar, S. S.; Bisht, Geetika; Dayanand, S.; Devi, Reena; Deshpande, S. S.; Chaudhary, S.; Bhatt, B. C.; Kannan, S.

    2007-01-01

    Stereotactic radiosurgery (SRS) is a special radiotherapy technique used to irradiate intracranial lesions by 3-D arrangements of narrow photon beams eliminating the needs of invasive surgery. Three different tertiary collimators, namely BrainLab and Radionics circular cones and BrainLab micro multileaf collimator (mMLC), are used for linear accelerator-based SRS systems (X-Knife). Output factor (St), tissue maximum ratio (TMR) and off axis ratio (OAR) of these three SRS systems were measured using CC01 (Scanditronix/ Welhofer) and Pinpoint (PTW) cylindrical and Markus plane parallel ionization chambers as well as TLD and radiochromic film. Measurement results of CC01 and Pinpoint chambers were very close to each other which indicate that further reduction in volume and physical dimensions of cylindrical ionization chamber is not necessary for SRS/SRT dosimetry. Output factors of BrainLab and Radionics SRS cones were very close to each other while output factors of equivalent diameter mMLC field were different from SRS circular cones. TMR of the three SRS systems compared were very close to one another. OAR of Radionics cone and BrainLab mMLC were very close to each other, within 2%. However, OARs of BrainLab cone were found comparable to OARs of Radionics cone and BrainLab mMLC within maximum variation of 4%. In addition, user-measured similar data of other three mMLC X-Knives were compared with the mMLC X-Knife data measured in this work and found comparable. The concept of switching over to mMLC-based SRS/SRT is thus validated from dosimetric characteristics as well. PMID:21217914

  1. 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

  2. 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.

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

    SciTech Connect

    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. 13 figs., 4 tabs.

  4. An accelerator-based epithermal photoneutron source for BNCT

    SciTech Connect

    Nigg, D.W.; Mitchell, H.E.; Harker, Y.D.; Yoon, W.Y.

    1995-11-01

    Therapeutically-useful epithermal-neutron beams for BNCT are currently generated by nuclear reactors. Various accelerator-based neutron sources for BNCT have been proposed and some low intensity prototypes of such sources, generally featuring the use of proton beams and beryllium or lithium targets have been constructed. This paper describes an alternate approach to the realization of a clinically useful accelerator-based source of epithermal neutrons for BNCT that reconciles the often conflicting objectives of target cooling, neutron beam intensity, and neutron beam spectral purity via a two stage photoneutron production process.

  5. Beam shaping assembly optimization for (7)Li(p,n)(7)Be accelerator based BNCT.

    PubMed

    Minsky, D M; Kreiner, A J

    2014-06-01

    Within the framework of accelerator-based BNCT, a project to develop a folded Tandem-ElectroStatic-Quadrupole accelerator is under way at the Atomic Energy Commission of Argentina. The proposed accelerator is conceived to deliver a proton beam of 30mA at about 2.5MeV. In this work we explore a Beam Shaping Assembly (BSA) design based on the (7)Li(p,n)(7)Be neutron production reaction to obtain neutron beams to treat deep seated tumors. PMID:24345525

  6. Atomic physics at the Argonne PII ECR (electron cyclotron resonance) Ion Source

    SciTech Connect

    Dunford, R.W.; Berry, H.G.; Billquist, P.J.; Pardo, R.C.; Zabransky, B.J.; Bakke, E.; Groeneveld, K.O.; Hass, M.; Raphaelian, M.L.A.

    1987-01-01

    An atomic physics beam line has been set up at the Argonne PII ECR Ion Source. The source is on a 350-kV high-voltage platform which is a unique feature of particular interest in work on atomic collisions. We describe our planned experimental program which includes: measurement of state-selective electron-capture cross sections, studies of doubly-excited states, precision spectroscopy of few-electron ions, tests of quantum electrodynamics, and studies of polarization transfer using optically pumped polarized alkali targets. The first experiments will be measurements of cross sections for electron capture into specific nl subshells in ion-atom collisions. Our method is to observe the characteristic radiation emitted after capture using a VUV spectrometer. Initial data from these experiments are presented. 12 refs., 4 figs.

  7. Physical essence of the multibody contact-sliding at atomic scale

    NASA Astrophysics Data System (ADS)

    Han, Xuesong

    2014-01-01

    Investigation the multibody contact-sliding occurred at atomic discrete contact spot will play an important role in determine the origin of tribology behavior and evaluates the micro-mechanical property of nanomaterials and thus optimizing the design of surface texture. This paper carries out large scale parallel molecular dynamics simulation on contact-sliding at atomic scale to uncover the special physical essence. The research shows that some kind of force field exists between nanodot pair and the interaction can be expressed by the linear combination of exponential function while the effective interaction distance limited in 1 angstrom for nanodot with several tens of nanometer diameter. The variation tendency about the interaction force between nanodot array is almost the same between nanodot pairs and thus the interaction between two nanodot array can be characterized by parallel mechanical spring. Multibody effect which dominates the interaction between atoms or molecules will gradually diminish with the increasing of length scales.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. 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

  11. 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.

  12. 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

  13. 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

    2014-01-01

    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 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. PMID:24796259

  14. LASER-PLASMA-ACCELERATOR-BASED GAMMA GAMMA COLLIDERS

    SciTech Connect

    Schroeder, C. B.; Esarey, E.; Toth, Cs.; Geddes, C. G. R.; Leemans, W. P.

    2009-05-04

    Design considerations for a next-generation linear collider based on laser-plasma-accelerators are discussed, and a laser-plasma-accelerator-based gamma-gamma collider is considered. An example of the parameters for a 0.5 TeV laser-plasma-accelerator gamma gamma collider is presented.

  15. 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.

  16. Focus on topological physics: from condensed matter to cold atoms and optics

    NASA Astrophysics Data System (ADS)

    Zhai, Hui; Rechtsman, Mikael; Lu, Yuan-Ming; Yang, Kun

    2016-08-01

    The notions of a topological phase and topological order were first introduced in the studies of integer and fractional quantum Hall effects, and further developed in the study of topological insulators and topological superconductors in the past decade. Topological concepts are now widely used in many branches of physics, not only limited to condensed matter systems but also in ultracold atomic systems, photonic materials and trapped ions. Papers published in this focus issue are direct testaments of that, and readers will gain a global view of how topology impacts different branches of contemporary physics. We hope that these pages will inspire new ideas through communication between different fields.

  17. Enhanced synthesis of Sn nanowires with aid of Se atom via physical vapor transport

    NASA Astrophysics Data System (ADS)

    Cai, Huacheng; Wang, Wendong; Liu, Peiwen; Wang, Guangming; Liu, Ankang; He, Zhe; Cheng, Zhaofang; Zhang, Shengli; Xia, Minggang

    2015-06-01

    We demonstrate tin (Sn) nanowires growth enhanced by Selenium (Se) atoms via physical vapor transport (PVT) method. The Raman spectroscopy, X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy show that Sn nanowires are synthesized with a large quantity, good quality and high purity of Sn. The growth of Sn nanowires is attributed to Solid-Vapor-Liquid mechanism. The effects of gold nanoparticles catalyst, Si substrate, and Se atoms on Sn nanowires growth are discussed in detail. We find that Se atom plays a key role in the growth of Sn nanowires. The gaseous Sn atoms are absorbed by the eutectic alloy droplets of Se-Au at first. Then Sn atoms precipitate at the liquid-solid phase interface due to a supersaturated solution and form a one-dimensional nanostructure. In all, this PVT method could provide a simple and quick way to synthesize monocrystalline Sn nanowires with an advantage in both quality and quantity. The optical transmittance of Sn nanowires thin film with 2 μm2 density approaches 85-90% in visible wavelength. Therefore, the Sn nanowires thin film can be applied to transparent electrode along with their metallic property.

  18. Atomic Physics in ITER — The Foundation for the Next Step to Fusion Power

    NASA Astrophysics Data System (ADS)

    Stotler, D. P.; Bell, R. E.; Hill, K. W.; Johnson, D. W.; Levinton, F. M.

    2007-04-01

    ITER represents the next step towards practical magnetic confinement fusion power. Its primary physics objective is to study plasmas in which the fusion power exceeds the external heating power by a factor of 5 to 10; its technological objectives include the use of superconducting magnets and remote maintenance. We will describe the ITER experiment and then detail the fundamental roles that will be played by atomic physics processes in facilitating the achievement of ITER's objectives. First, atoms and molecules generated by the interaction of the ITER plasma with surrounding material surfaces will impact and, in some respects, dominate the particle, momentum, and energy balances in both the adjacent and confined, core plasmas. Second, impurity radiation in the edge plasma, either from intrinsic or extrinsic species, will ensure that heat coming out from the core is spread more uniformly over the surrounding material surfaces than it would otherwise. Third, many of the diagnostics used to monitor the dense (ne ˜ 1020 m-3), hot (˜ 1 × 108 K) core plasma leverage off of atomic physics effects.

  19. 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.

  20. 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

  1. Physics Division progress report for period ending September 30, 1985

    SciTech Connect

    Livingston, A.B.

    1986-04-01

    This report covers the research and development activities of the Physics Division for the 1985 fiscal year. The research activities were centered on experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. The experimental nuclear physics program is dominated by heavy ion research. A major part of this effort is the responsibility for operating the Holifield Heavy Ion Research Facility as a national user facility. A major new activity described is the preparation for participation in an ultrarelativistic heavy ion experiment to be performed at CERN in 1986. The experimental atomic physics program has two components: the accelerator-based studies of basic collisional phenomena and the studies in support of the controlled fusion program. Also associated with the fusion-related studies are a plasma diagnostics program and the operation of an atomic physics data center. Theory efforts associated with the UNISOR program are described, as well as smaller programs in applications and high-energy physics. (LEW)

  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. PMID:27517608

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Leibrandt, D. R.; Heidecker, J.

    2015-12-01

    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.

  8. 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.

  9. 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…

  10. 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…

  11. 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

  12. Physical and chemical nature of the scaling relations between adsorption energies of atoms on metal surfaces.

    PubMed

    Calle-Vallejo, F; Martínez, J I; García-Lastra, J M; Rossmeisl, J; Koper, M T M

    2012-03-16

    Despite their importance in physics and chemistry, the origin and extent of the scaling relations between the energetics of adsorbed species on surfaces remain elusive. We demonstrate here that scalability is not exclusive to adsorbed atoms and their hydrogenated species but rather a general phenomenon between any set of adsorbates bound similarly to the surface. On the example of the near-surface alloys of Pt, we show that scalability is a result of identical variations of adsorption energies with respect to the valence configuration of both the surface components and the adsorbates. PMID:22540492

  13. 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.

  14. Nuclear-Spin-Independent Short-Range Three-Body Physics in Ultracold Atoms

    SciTech Connect

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

    2010-09-03

    We investigate three-body recombination loss across a Feshbach resonance in a gas of ultracold {sup 7}Li atoms prepared in the absolute ground state and perform a comparison with previously reported results of a different nuclear-spin state [N. Gross et al., 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.

  15. 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.

  16. 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.

  17. The design of the RF cavity for the heavy ion storage ring for atomic physics

    SciTech Connect

    Mosko, S.W.

    1990-01-01

    An rf cavity and drive system have been designed for the proposed Heavy Ion Storage Ring for Atomic Physics,'' HISTRAP, at Oak Ridge. A peak accelerating voltage of 2.5 kV per turn is required with a continuous tuning range from 200 kHz through 2.7 MHz. A single-gap, half-wave resonant configuration is used with biased ferrite tuning. The cavity structure is completely outside of the beam line/vacuum enclosure except for a single rf window that serves as an accelerating gap. Physical separation of the cavity and beam line permits in situ vacuum baking of the beam line components at 300{degree}C. A prototype cavity was designed, built, and tested. Development of frequency synthesizer and tuner control circuitry is under way.

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

    NASA Astrophysics Data System (ADS)

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

    1987-04-01

    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. An overview of the field, current plans, and future possibilities will be presented.

  19. Accelerator-based conversion (ABC) of reactor and weapons plutonium

    SciTech Connect

    Jensen, R.J.; Trapp, T.J.; Arthur, E.D.; Bowman, C.D.; Davidson, J.W.; Linford, R.K.

    1993-06-01

    An accelerator-based conversion (ABC) system is presented that is capable of rapidly burning plutonium in a low-inventory sub-critical system. The system also returns fission power to the grid and transmutes troublesome long-lived fission products to short lived or stable products. Higher actinides are totally fissioned. The system is suited not only to controlled, rapid burning of excess weapons plutonium, but to the long range application of eliminating or drastically reducing the world total inventory of plutonium. Deployment of the system will require the successful resolution of a broad range of technical issues introduced in the paper.

  20. Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy

    SciTech Connect

    Herrera, Maria S.; Gonzalez, Sara J.; Minsky, Daniel M.; Kreiner, Andres J.

    2010-08-04

    Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator-based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton-induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose-volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator-based BNCT treatment.

  1. Treatment Planning for Accelerator-Based Boron Neutron Capture Therapy

    NASA Astrophysics Data System (ADS)

    Herrera, María S.; González, Sara J.; Minsky, Daniel M.; Kreiner, Andrés J.

    2010-08-01

    Glioblastoma multiforme and metastatic melanoma are frequent brain tumors in adults and presently still incurable diseases. Boron Neutron Capture Therapy (BNCT) is a promising alternative for this kind of pathologies. Accelerators have been proposed for BNCT as a way to circumvent the problem of siting reactors in hospitals and for their relative simplicity and lower cost among other advantages. Considerable effort is going into the development of accelerator-based BNCT neutron sources in Argentina. Epithermal neutron beams will be produced through appropriate proton-induced nuclear reactions and optimized beam shaping assemblies. Using these sources, computational dose distributions were evaluated in a real patient with diagnosed glioblastoma treated with BNCT. The simulated irradiation was delivered in order to optimize dose to the tumors within the normal tissue constraints. Using Monte Carlo radiation transport calculations, dose distributions were generated for brain, skin and tumor. Also, the dosimetry was studied by computing cumulative dose-volume histograms for volumes of interest. The results suggest acceptable skin average dose and a significant dose delivered to tumor with low average whole brain dose for irradiation times less than 60 minutes, indicating a good performance of an accelerator-based BNCT treatment.

  2. Non-local physics: Applications from the universe evolution to the atom structure in the frame of the unified theory

    NASA Astrophysics Data System (ADS)

    Alexeev, B. V.

    2013-10-01

    The main principles of the non-local physics are delivered. The unified theory of transport processes is applicable to the physical systems in tremendous diapason of scales - from atom structures to the Universe evolution. The origin of difficulties connected with the hypothetical dark matter and dark energy consists in the total Oversimplification following from the principles of local physics and reflects the general shortcomings of the local kinetic transport theory.

  3. Two-body physics in quasi-low-dimensional atomic gases under spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wang, Jing-Kun; Yi, Wei; Zhang, Wei

    2016-06-01

    One of the most dynamic directions in ultracold atomic gas research is the study of low-dimensional physics in quasi-low-dimensional geometries, where atoms are confined in strongly anisotropic traps. Recently, interest has significantly intensified with the realization of synthetic spin-orbit coupling (SOC). As a first step toward understanding the SOC effect in quasi-low-dimensional systems, the solution of two-body problems in different trapping geometries and different types of SOC has attracted great attention in the past few years. In this review, we discuss both the scattering-state and the bound-state solutions of two-body problems in quasi-one and quasi-two dimensions. We show that the degrees of freedom in tightly confined dimensions, in particular with the presence of SOC, may significantly affect system properties. Specifically, in a quasi-one-dimensional atomic gas, a one-dimensional SOC can shift the positions of confinement-induced resonances whereas, in quasitwo- dimensional gases, a Rashba-type SOC tends to increase the two-body binding energy, such that more excited states in the tightly confined direction are occupied and the system is driven further away from a purely two-dimensional gas. The effects of the excited states can be incorporated by adopting an effective low-dimensional Hamiltonian having the form of a two-channel model. With the bare parameters fixed by two-body solutions, this effective Hamiltonian leads to qualitatively different many-body properties compared to a purely low-dimensional model.

  4. 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.

  5. An all-optical vector atomic magnetometer for fundamental physics applications

    NASA Astrophysics Data System (ADS)

    Wurm, David; Mateos, Ignacio; Zhivun, Elena; Patton, Brian; Fierlinger, Peter; Beck, Douglas; Budker, Dmitry

    2014-05-01

    We have developed a laboratory prototype of a compact all-optical vector magnetometer. Due to their high precision and absolute accuracy, atomic magnetometers are crucial sensors in fundamental physics experiments which require extremely stable magnetic fields (e.g., neutron EDM searches). This all-optical sensor will allow high-resolution measurements of the magnitude and direction of a magnetic field without perturbing the magnetic environment. Moreover, its absolute accuracy makes it calibration-free, an advantage in space applications (e.g., space-based gravitational-wave detection). Magnetometry in precision experiments or space applications also demands long-term stability and well-understood noise characteristics at frequencies below 10-4 Hz. We have characterized the low-frequency noise floor of this sensor and will discuss methods to improve its long-time performance.

  6. 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.

  7. 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.

  8. 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.

  9. 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. PMID:24850237

  10. Thin film semiconductor nanomaterials and nanostructures prepared by physical vapour deposition: An atomic force microscopy study

    NASA Astrophysics Data System (ADS)

    Nesheva, D.; Petrova, A.; Stavrev, S.; Levi, Z.; Aneva, Z.

    2007-05-01

    Amorphous/nanocrystalline SiOx/CdSe, GeS2/CdSe, SiOx/ZnSe and Se/CdSe amorphous multilayers (MLs) were grown by consecutive physical vapour deposition of the constituent materials at room substrate temperature. A step-by-step manner of deposition was applied for the preparation of each layer (2 10nm thick) of MLs. Surface morphology has been investigated by atomic force microscopy (AFM) in order to get information about ML interfaces. For a scanned area of 3.4×4μmSiOx/CdSe and GeS2/CdSe MLs showed surface roughness which is around three times greater than the roughness of SiOx/ZnSe MLs. This observation has been connected with effects of both film composition and deposition rate. For a scanned area of 250×250nm the roughness determined in all MLs displayed close values and a similar increase with the ML period. The latter has been related to the flexible structure of amorphous materials. The AFM results, in good agreement with previous X-ray diffraction and high resolution electron microscopy data, indicate that the application of step-by-step physical vapour deposition makes possible fabrication of various amorphous/nanocrystalline MLs with smooth interfaces and good artificial periodicity at low substrate temperatures.

  11. A neutron producing target for BINP accelerator-based neutron source.

    PubMed

    Bayanov, B; Kashaeva, E; Makarov, A; Malyshkin, G; Samarin, S; Taskaev, S

    2009-07-01

    An innovative accelerator-based neutron source for BNCT has just started operation at the Budker Institute of Nuclear Physics, Novosibirsk. One of the main elements of the facility is a lithium target producing neutrons via the threshold (7)Li(p,n)(7)Be reaction at 25 kW proton beam with energies of 1.915 MeV or 2.5 MeV. The design of an optimal target and results of the investigation of radiation blistering of the lithium layer were presented at previous NCT Congresses. During the last two years the neutron target has been manufactured, assembled and placed in the facility. Optimization of the target is carried out with the Monte Carlo simulation code MCNP. In this article, the design of the target is discussed, results of all previous investigations are summarized, results of target testing and neutron generation are described, and results of simulation of neutron spectra are presented. PMID:19376729

  12. 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.

  13. Accelerator Based Neutron Beams for Neutron Capture Therapy

    SciTech Connect

    Yanch, Jacquelyn C.

    2003-04-11

    The DOE-funded accelerator BNCT program at the Massachusetts Institute of Technology has resulted in the only operating accelerator-based epithermal neutron beam facility capable of generating significant dose rates in the world. With five separate beamlines and two different epithermal neutron beam assemblies installed, we are currently capable of treating patients with rheumatoid arthritis in less than 15 minutes (knee joints) or 4 minutes (finger joints) or irradiating patients with shallow brain tumors to a healthy tissue dose of 12.6 Gy in 3.6 hours. The accelerator, designed by Newton scientific Incorporated, is located in dedicated laboratory space that MIT renovated specifically for this project. The Laboratory for Accelerator Beam Applications consists of an accelerator room, a control room, a shielded radiation vault, and additional laboratory space nearby. In addition to the design, construction and characterization of the tandem electrostatic accelerator, this program also resulted in other significant accomplishments. Assemblies for generating epithermal neutron beams were designed, constructed and experimentally evaluated using mixed-field dosimetry techniques. Strategies for target construction and target cooling were implemented and tested. We demonstrated that the method of submerged jet impingement using water as the coolant is capable of handling power densities of up to 6 x 10(sup 7) W/m(sup 2) with heat transfer coefficients of 10(sup 6)W/m(sup 2)-K. Experiments with the liquid metal gallium demonstrated its superiority compared with water with little effect on the neutronic properties of the epithermal beam. Monoenergetic proton beams generated using the accelerator were used to evaluate proton RBE as a function of LET and demonstrated a maximum RBE at approximately 30-40 keV/um, a finding consistent with results published by other researchers. We also developed an experimental approach to biological intercomparison of epithermal beams and

  14. 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.

  15. 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.

  16. Precision determination of electroweak coupling from atomic parity violation and implications for particle physics.

    PubMed

    Porsev, S G; Beloy, K; Derevianko, A

    2009-05-01

    We carry out high-precision calculation of parity violation in a cesium atom, reducing theoretical uncertainty by a factor of 2 compared to previous evaluations. We combine previous measurements with calculations and extract the weak charge of the 133Cs nucleus, QW=-73.16(29)expt(20)theor. The result is in agreement with the standard model (SM) of elementary particles. This is the most accurate to-date test of the low-energy electroweak sector of the SM. In combination with the results of high-energy collider experiments, we confirm the energy dependence (or "running") of the electroweak force over an energy range spanning 4 orders of magnitude (from approximately 10 MeV to approximately 100 GeV). Additionally, our result places constraints on a variety of new physics scenarios beyond the SM. In particular, we increase the lower limit on the masses of extra Z bosons predicted by models of grand unification and string theories. PMID:19518856

  17. 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

  18. Cold-Atom Physics Using Ultrathin Optical Fibers: Light-Induced Dipole Forces and Surface Interactions

    SciTech Connect

    Sague, 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.

  19. 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…

  20. 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…

  1. 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.

  2. Advances in boron neutron capture therapy (BNCT) at kyoto university - From reactor-based BNCT to accelerator-based BNCT

    NASA Astrophysics Data System (ADS)

    Sakurai, Yoshinori; Tanaka, Hiroki; Takata, Takushi; Fujimoto, Nozomi; Suzuki, Minoru; Masunaga, Shinichiro; Kinashi, Yuko; Kondo, Natsuko; Narabayashi, Masaru; Nakagawa, Yosuke; Watanabe, Tsubasa; Ono, Koji; Maruhashi, Akira

    2015-07-01

    At the Kyoto University Research Reactor Institute (KURRI), a clinical study of boron neutron capture therapy (BNCT) using a neutron irradiation facility installed at the research nuclear reactor has been regularly performed since February 1990. As of November 2014, 510 clinical irradiations were carried out using the reactor-based system. The world's first accelerator-based neutron irradiation system for BNCT clinical irradiation was completed at this institute in early 2009, and the clinical trial using this system was started in 2012. A shift of BCNT from special particle therapy to a general one is now in progress. To promote and support this shift, improvements to the irradiation system, as well as its preparation, and improvements in the physical engineering and the medical physics processes, such as dosimetry systems and quality assurance programs, must be considered. The recent advances in BNCT at KURRI are reported here with a focus on physical engineering and medical physics topics.

  3. Relating the physical properties of Pseudomonas aeruginosa lipopolysaccharides to virulence by atomic force microscopy.

    PubMed

    Ivanov, Ivan E; Kintz, Erica N; Porter, Laura A; Goldberg, Joanna B; Burnham, Nancy A; Camesano, Terri A

    2011-03-01

    Lipopolysaccharides (LPS) are an important class of macromolecules that are components of the outer membrane of Gram-negative bacteria such as Pseudomonas aeruginosa. P. aeruginosa contains two different sugar chains, the homopolymer common antigen (A band) and the heteropolymer O antigen (B band), which impart serospecificity. The characteristics of LPS are generally assessed after isolation rather than in the context of whole bacteria. Here we used atomic force microscopy (AFM) to probe the physical properties of the LPS of P. aeruginosa strain PA103 (serogroup O11) in situ. This strain contains a mixture of long and very long polymers of O antigen, regulated by two different genes. For this analysis, we studied the wild-type strain and four mutants, ΔWzz1 (producing only very long LPS), ΔWzz2 (producing only long LPS), DΔM (with both the wzz1 and wzz2 genes deleted), and Wzy::GM (producing an LPS core oligosaccharide plus one unit of O antigen). Forces of adhesion between the LPS on these strains and the silicon nitride AFM tip were measured, and the Alexander and de Gennes model of steric repulsion between a flat surface and a polymer brush was used to calculate the LPS layer thickness (which we refer to as length), compressibility, and spacing between the individual molecules. LPS chains were longest for the wild-type strain and ΔWzz1, at 170.6 and 212.4 nm, respectively, and these values were not statistically significantly different from one another. Wzy::GM and DΔM have reduced LPS lengths, at 34.6 and 37.7 nm, respectively. Adhesion forces were not correlated with LPS length, but a relationship between adhesion force and bacterial pathogenicity was found in a mouse acute pneumonia model of infection. The adhesion forces with the AFM probe were lower for strains with LPS mutations, suggesting that the wild-type strain is optimized for maximal adhesion. Our research contributes to further understanding of the role of LPS in the adhesion and virulence of

  4. 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)

  5. 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.

  6. Liquid atomization

    NASA Astrophysics Data System (ADS)

    Bayvel, L.; Orzechowski, Z.

    The present text defines the physical processes of liquid atomization, the primary types of atomizers and their design, and ways of measuring spray characteristics; it also presents experimental investigation results on atomizers and illustrative applications for them. Attention is given to the macrostructural and microstructural parameters of atomized liquids; swirl, pneumatic, and rotary atomizers; and optical drop sizing methods, with emphasis on nonintrusive optical methods.

  7. 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.

  8. Atomic and molecular physics and data activities for astrophysics at Oak Ridge National Laboratory

    SciTech Connect

    Jeffery, D.J.; Kristic, P.S.; Liu, W.; Schultz, D.R.; Stancil, P.C.

    1998-04-01

    The atomic astrophysics group at ORNL produces, collects, evaluates, and disseminates atomic and molecular data relevant to astrophysics and actively models various astrophysical environments utilizing this information. With the advent of the World Wide Web, these data are also being placed on-line to facilitate their use by end-users. In this brief report, the group`s recent activities in data production and in modeling are highlighted. For example, the authors describe recent calculations of elastic and transport cross sections relevant to ionospheric and heliospheric studies, charge transfer between metal ions and metal atoms and novel supernova nebular spectra modeling, ion-molecule collision data relevant to planetary atmospheres and comets, and data for early universe modeling.

  9. Future directions of accelerator-based NP and HEP facilities

    SciTech Connect

    Roser, T.

    2011-07-24

    Progress in particle and nuclear physics has been closely connected to the progress in accelerator technologies - a connection that is highly beneficial to both fields. This paper presents a review of the present and future facilities and accelerator technologies that will push the frontiers of high-energy particle interactions and high intensity secondary particle beams.

  10. Future directions of accelerator-based NP and HEP facilities

    NASA Astrophysics Data System (ADS)

    Roser, Thomas

    2012-09-01

    Progress in particle and nuclear physics has been closely connected to the progress in accelerator technologies - a connection that is highly beneficial to both fields. This paper presents a review of the present and future facilities and accelerator technologies that will push the frontiers of high-energy particle interactions and high intensity secondary particle beams.

  11. Quantum double-exchange physics with ultracold atoms and synthetic gauge potentials

    NASA Astrophysics Data System (ADS)

    Schachenmayer, Johannes; Isaev, Leonid; Rey, Ana Maria

    We study an interplay between local spin exchange and Néel antiferromagnetism in a two-band optical lattice. The lowest narrow band is half-filled and implements the magnetic background, while a higher band contains mobile atoms. When the local spins are locked in a Néel state, the motion of itinerant atoms is hindered by exchange energy barriers and the system is a flat-band insulator. As we show, this picture breaks down when exchange interaction between local and mobile spins is comparable to an energy scale of the Néel state. In this regime, formation of singlets between local and itinerant spins gives rise to a metallic phase of mobile atoms dressed by the spin fluctuations. This state is characterized by coupled spin-charge excitations whose spin is transverse to the Néel vector. Our predictions can be realized with ultracold alkaline-earth fermionic atoms coupled to a laser-induced staggered magnetic field, which stabilizes the Néel order and controls the amount of quantum fluctuations of local spins. By tuning the strength of this laser coupling relative to the exchange interaction, one can either adiabatically drive the crossover between the flat-band insulator and correlated metal phases, or explore non-equilibrium spin-charge dynamics in quench experiments. This work was supported by the NSF (PIF-1211914 and PFC-1125844), AFOSR, AFOSR-MURI, NIST and ARO individual investigator awards.

  12. 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.

  13. 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…

  14. 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.

  15. 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.

  16. First neutron generation in the BINP accelerator based neutron source.

    PubMed

    Bayanov, B; Burdakov, A; Chudaev, V; Ivanov, A; Konstantinov, S; Kuznetsov, A; Makarov, A; Malyshkin, G; Mekler, K; Sorokin, I; Sulyaev, Yu; Taskaev, S

    2009-07-01

    Pilot innovative facility for neutron capture therapy was built at Budker Institute of Nuclear Physics, Novosibirsk. This facility is based on a compact vacuum insulation tandem accelerator designed to produce proton current up to 10 mA. Epithermal neutrons are proposed to be generated by 1.915 MeV protons bombarding a lithium target using (7)Li(p,n)(7)Be threshold reaction. The results of the first experiments on neutron generation are reported and discussed. PMID:19375928

  17. 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

  18. Recent developments in atomic physics for the simulation of hot plasmas

    NASA Astrophysics Data System (ADS)

    Klapisch, M.; Bar-Shalom, A.; Oreg, J.; Colombant, D.

    2001-05-01

    Simulations of plasmas in which atoms are not completely stripped require atomic data, like average charge, ionization energies, and radiative properties (emissivity, opacity). These depend on populations of energy levels. The basic framework for obtaining the latter is the collisional radiative model (CRM), which bridges the gap between the low-density Corona Equilibrium (CE) and Local Thermodynamic Equilibrium (LTE). However, for nearly all but the simplest ions, the number of relevant bound states and cross sections is prohibitive. In this review we summarize some recent methods for handling complex ions: By focusing on an exact evaluation of relevant information and ignoring unobservable features, unresolved transition arrays (UTA) are obtained. The supertransition arrays (STA) model combines many UTAs in LTE. The STA code was recently extended to a non-LTE CRM called SCROLL. Using these models could improve radiation simulation in hot plasmas, even for simple spectra.

  19. Spectroscopy of Z-pinch plasmas: how atomic and plasma physics merge and unfold new applications

    NASA Astrophysics Data System (ADS)

    Safronova, Alla

    2012-06-01

    Recent advances in theoretical and experimental work on plasma spectroscopy of Z-pinches are presented. We have shown that the University-scale Z-pinch generators are able to produce plasmas within a broad range of temperatures, densities, opacity, and radiative properties depending on the type, geometry, size, and mass of wire array loads and wire material. The full x-ray and EUV diagnostic set for detailed spatial and temporal monitoring of such a plasma together with relativistic atomic and non-LTE kinetic codes create a very useful and productive environment for the study of atomic and plasma spectroscopy features and development of their applications. A variety of examples of K-shell low-Z (such as Mg and Al), L-shell mid-Z (such as Ni, Cu, and Ag), and M- and L-shell high-Z (W) will be considered and their specific features and applications to fusion and astrophysics will be highlighted.

  20. 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.

  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 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).

  3. 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.

  4. Interplay of particle, nuclear and atomic physics in rare weak decays

    NASA Astrophysics Data System (ADS)

    Suhonen, Jouni

    2010-11-01

    The neutrinoless double beta decays of atomic nuclei are considered at the present the most viable way to access the fundamenntal nature and absolute mass scale of the neutrino. Recently one sub-class of these decays, the neutrinoless double electron capture (0νECEC), has attracted a lot of attention due to its potential of detection. In particular, the resonant 0νECEC is of interest owing to the possible huge enhancement of the corresponding decay rate by a resonance condition. At present the mass differences of the involved atom pairs are being measured by the Penning trap technique for several potential resonant 0νECEC decays. By evaluating the associated nuclear matrix elements using nuclear-structure models one can access the half-lives of these decays and thus predict their detection potential in underground experiments in the future. The absolute mass scale of the neutrino can also be accessed through beta decays of small decay energy. In these cases the effects of atomic origin may introduce non-negligible, even dramatic effects for Q values in the regime of few hundreds of eV and below.

  5. Limitations of the semirelativistic approach in sum rules and related calculations in atomic physics

    NASA Technical Reports Server (NTRS)

    Rustgi, M. L.; Leung, P. T.; Long, S. A. T.

    1988-01-01

    The semirelativistic approach, as applied to sum-rule calculations, can yield very inaccurate results for high-Z systems; the apparently good agreement previously reported is fortuitous, due to the application of an approximate eigenstate of the semirelativistic Hamiltonian. Attention is given to one-electron atomic systems, and the results obtained are discussed with a view to their implications for many-electron systems. The many-electron problem is complicated by a lack of clarity as to the relative importance of contributions due to correlation effects among the electrons, their effect on the E2 oscillator strength, and the retardation correction to the E1 transition.

  6. 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…

  7. Physics Division progress report for period ending September 30, 1987

    SciTech Connect

    Livingston, A.B.

    1988-03-01

    The activities of this Division are concentrated in the areas of experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. A major activity within the Division is operation of the Holifield Heavy Ion Research Facility as a national user facility. Highlights for this year, which include a record number of beam hours provided for research, are summarized. The experimental nuclear physics program continues to be dominated by research utilizing heavy ions. These activities, while continuing to center largely on the Holifield Facility, have seen growth in the use of facilities that provide intermediate energies (GANIL) and ultrarelativistic beams (CERN). The UNISOR program, since its inception, has been intimately associated with the Division and, most particularly, with the Holifield Facility. The experimental nuclear structure research of this consortium is included. In addition to the Holifield Facility, the Division also operates two smaller facilities, the EN Tandem and the ECR Ion Source Facility, as /open quotes/User Resources/close quotes/. The tandem continues a long history of supporting research in accelerator-based atomic physics. During this past year, new beam lines have been added to the ECR ion source to create user opportunities for atomic physics experiments with this unique device. These two facilities and the experimental programs in atomic physics are discussed. The efforts in theoretical physics, covering both nuclear and atomic physics, are presented. Also included is the theory effort in support of the UNISOR structure program. In addition to research with multicharged heavy ions from the ECR source, the effort on atomic physics in support of the controlled fusion program includes a plasma diagnostics development program and operation of an atomic physics data center. The nuclear physics program also operates a compilation and evaluation effort; this work is also described.

  8. 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.

  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. 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.

  11. 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.

  12. The physical basis for absorption of light. [effects on wave functions of gas molecules and atoms

    NASA Technical Reports Server (NTRS)

    Pickett, H. M.

    1979-01-01

    The effects of light absorption on the wave functions of gas-phase molecules and atoms are investigated by high resolution spectral measurements of radiation emerging from a sample. A Stark-modulated sample of methyl fluoride was irradiated at the 102 GHz rotational transition and the emergent radiation was resolved by means of a spectrum analyzer. For signal oscillator frequencies below or above the molecular resonance by one modulation frequency, the amplitudes of the upper and lower modulation sidebands are found to be of nonuniform intensity, which is inconsistent with amplitude modulation. Emission due to polarization is, however, calculated to be consistent with the results observed, indicating that light absorption should be considered as a subtractive stimulated emission.

  13. 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.

  14. 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

  15. Theoretical study of heavy-atom molecules to search for physics beyond the Standard model

    NASA Astrophysics Data System (ADS)

    Petrov, A. N.; Skripnikov, L. V.; Kudashov, A. D.; Mosyagin, N. S.; Titov, A. V.

    2015-05-01

    The goal of the report is to review our latest studies for heavy-atom diatomics - ThO, RaO, RaF, PbF - which are of practical interest to search the T, P-odd effects. Particular attention is devoted to the H3Δ1 state of ThO. Combination of the spin precession measurement of ThO with the calculated Eeff (ThO) leads to the most rigid limit on eEDM:, |de|<8.7 × 10-29e .cm. This is more than one order of magnitude better than other limits obtained. The knowledge of the g-factor dependence on electric fields is important for understanding possible systematic effects. Our study of the g-factors for H3Δ1 has shown that the J = 2 rotational state should be even more robust against a number of systematic errors compared to J = 1. This work is supported by the SPbU Fundamental Science Research grant from Federal Budget No. 0.38.652.2013, RFBR Grant No. 13-02-01406. L.S. is also grateful to the President of RF grant no MK-5877.2014.2.

  16. Atomic effects of beta decay in astrophysics and in elementary particle physics

    NASA Astrophysics Data System (ADS)

    Chen, Zonghua

    The bound-state beta decay of Re-187 and its application in Astrophysics is studied. There existed an uncertainty in the ratio of rhop of bound-state to continuum beta decay of Re-187 in both theory and experiment. A more definite theoretical result of rhop of approximately 1 percent is obtained by using single-configuration and multi-configuration Hartree-Fock-Dirac approximations. The results obtained are close to those obtained by Williams, Fowler, and Koonin by a modified Thomas-Fermi model. The bound-state beta decay of Re-187 at high temperatures is also studied. A generalization of the Thomas-Fermi results of various energy contributions to the ground-state energy of a neutral atom is also presented. An analytical expression for the ratio of the electron-electron to electron-nuclear interaction is obtained by the corrected Thomas-Fermi result, the ratio obtained gives a better agreement with the Hartree-Fock numerical results.

  17. 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.

  18. Lithium target for accelerator based BNCT neutron source: Influence by the proton irradiation on lithium

    NASA Astrophysics Data System (ADS)

    Fujii, R.; Imahori, Y.; Nakakmura, M.; Takada, M.; Kamada, S.; Hamano, T.; Hoshi, M.; Sato, H.; Itami, J.; Abe, Y.; Fuse, M.

    2012-12-01

    The neutron source for Boron Neutron Capture Therapy (BNCT) is in the transition stage from nuclear reactor to accelerator based neutron source. Generation of low energy neutron can be achieved by 7Li (p, n) 7Be reaction using accelerator based neutron source. Development of small-scale and safe neutron source is within reach. The melting point of lithium that is used for the target is low, and durability is questioned for an extended use at a high current proton beam. In order to test its durability, we have irradiated lithium with proton beam at the same level as the actual current density, and found no deterioration after 3 hours of continuous irradiation. As a result, it is suggested that lithium target can withstand proton irradiation at high current, confirming suitability as accelerator based neutron source for BNCT.

  19. Description of the programs and facilities of the Physics Division

    SciTech Connect

    Not Available

    1992-10-01

    The major emphasis of our experimental nuclear physics research is in Heavy-Ion Physics, centered at the recently completed ATLAS facility. ATLAS is a designated National User Facility and is based on superconducting radio-frequency technology developed in the Physics Division. In addition, the Division has strong programs in Medium-Energy Physics and in Weak-Interaction Physics as well as in accelerator development. Our nuclear theory research spans a wide range of interests including nuclear dynamics with subnucleonic degrees of freedom, dynamics of many-nucleon systems, nuclear structure, and heavy-ion interactions. This research makes contact with experimental research programs in intermediate-energy and heavy-ion physics, both within the Division and on the national scale. The Atomic Physics program, the largest of which is accelerator-based, primarily uses ATLAS, a 5-MV Dynamitron accelerator and a highly stable 150-kV accelerator. A synchrotron-based atomic physics program has recently been initiated with current research with the National Synchrotron Light Source in preparation for a program at the Advanced Photon Source, at Argonne. The principal interests of the Atomic Physics program are in the interactions of fast atomic and molecular ions with solids and gases and in the laser spectroscopy of exotic species. The program is currently being expanded to take advantage of the unique research opportunities in synchrotron-based research that will present themselves when the Advanced Photon Source comes on line at Argonne. These topics are discussed briefly in this report.

  20. 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.

  1. GPS.DM Observatory: Search for Dark Matter and Exotic Physics with Atomic Clocks and GPS Constellation

    NASA Astrophysics Data System (ADS)

    Roberts, Benjamin; Blewitt, Geoffrey; Derevianko, Andrei; Lundholm, Nathan; Pospelov, Maxim; Rollings, Alex; Sherman, Jeff; GPS. DM Collaboration

    2016-05-01

    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, analyzing 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. This type of search is particularly sensitive to exotic forms of dark matter, such as topological defects. We will present an update on the search. Supported by the NSF.

  2. 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.

  3. 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.

  4. 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.

  5. Testing Universality of Efimov Physics in an Ultracold Mixture of Lithium and Cesium Atoms

    NASA Astrophysics Data System (ADS)

    Johansen, Jacob; Desalvo, Brian; Chin, Cheng

    2016-05-01

    We conduct a survey of Li-Cs-Cs Efimov resonances in a 6 Li-133 Cs mixture in the magnetic field range of 800 to 950 G. In this region, limiting our study to the two lowest Zeeman levels of lithium and the lowest Zeeman level of cesium, there are five Feshbach resonances which may be probed. The Cs-Cs scattering length at these resonances varies from -3600 a0 to +1000 a0, allowing us to study the impact of the Cs-Cs scattering length on the Efimov resonance positions. In addition, a combination of broad and narrow Feshbach resonances in this magnetic field range allows us to probe the influence of molecular physics on the Efimov effect, particularly the variation of the three-body parameter.

  6. Storage-ring experiments on dielectronic recombination at the interface of atomic and nuclear physics

    NASA Astrophysics Data System (ADS)

    Brandau, Carsten; Kozhuharov, Christophor; Lestinsky, Michael; Müller, Alfred; Schippers, Stefan; Stöhlker, Thomas

    2015-11-01

    A brief review about topical developments in the exploitation of the resonant electron-ion collision process of dielectronic recombination (DR) as a sensitive spectroscopic tool is given. The focus will be on DR storage-ring experiments of few-electron highly charged ions. Among others, the questions addressed in these studies cover diverse topics from the areas of strong-field quantum electrodynamics, of lifetime studies using DR resonances, and of nuclear physics. Examples from the storage rings CRYRING in Stockholm, TSR in Heidelberg, and ESR in Darmstadt are given. In addition, an overview is provided about the ongoing developments and future perspectives of DR collision spectroscopy at the upcoming Facility for Antiproton and Ion Research in Darmstadt, Germany.

  7. Energetic Neutral Atoms from the Moon: Populations, physics, applications, and the future

    NASA Astrophysics Data System (ADS)

    Futaana, Yoshifumi; Barabash, Stas; Wieser, Martin; Bhardwaj, Anil; Wurz, Peter

    Coexistence of plasma particles and neutral materials in space creates energetic neutral atoms (ENAs). For example, when solar wind plasma interacts with the lunar surface, ENA production is expected. We review recent investigations of the Moon-associated ENAs observed by a lunar orbiter, Chandrayaan-1, and discuss lessons learnt from the experiment. Intensive observations were conducted by the Chandrayaan-1 Energetic Neutrals Analyzer (CENA) sensor, the first and the only ever ENA sensor in a lunar orbit. CENA started its operation in the beginning of 2009. CENA can measure low energy ENAs, i.e. the energy below 3 keV. Using the dataset obtained from its 6-month operation, we discovered several populations of ENAs emitted from the Moon: begin{itemize} Backscattered ENAs of solar wind proton origin Backscattered ENAs of plasmasheet proton origin Sputtered hydrogen from the surface Indeed, backscattered ENAs had never expected as a major ENA population because the porosity (roughness) of the lunar surface is extremely high, and thus impinging plasma particles must have experienced several scattering to be absorbed. However, the observations clearly showed extremely high flux of backscattered ENAs. The discovery gave us a new insight in the field of low energy plasma interaction with porous surface in space. From the measured ENA flux and flying direction at the orbiter, we can derive the place of the ENA production and its flux at the lunar surface. They include information about solar wind plasma at the surface. One of the most attractive regions for investigation is a locally magnetized region (magnetic anomaly). Magnetic anomalies form mini-magnetospheres, which prevent the solar wind to precipitate. The efficiency of the protection influences directly the effectiveness of the space weathering by solar wind plasmas. Using the obtained CENA data, we could successfully image a reduction of the ENA flux inside known magnetic anomalies. The image clearly indicates

  8. 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.

  9. 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

  10. 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.

  11. Final Report: Particle Physics Research Program

    SciTech Connect

    Karchin, Paul E.

    2011-09-01

    We describe recent progress in accelerator-based experiments in high-energy particle physics and progress in theoretical investigations in particle physics. We also describe future plans in these areas.

  12. An in situ accelerator-based diagnostic for plasma-material interactions science on magnetic fusion devices

    SciTech Connect

    Hartwig, Zachary S.; Barnard, Harold S.; Lanza, Richard C.; Sorbom, Brandon N.; Stahle, Peter W.; Whyte, Dennis G.

    2013-12-15

    This paper presents a novel particle accelerator-based diagnostic that nondestructively measures the evolution of material surface compositions inside magnetic fusion devices. The diagnostic's purpose is to contribute to an integrated understanding of plasma-material interactions in magnetic fusion, which is severely hindered by a dearth of in situ material surface diagnosis. The diagnostic aims to remotely generate isotopic concentration maps on a plasma shot-to-shot timescale that cover a large fraction of the plasma-facing surface inside of a magnetic fusion device without the need for vacuum breaks or physical access to the material surfaces. Our instrument uses a compact (∼1 m), high-current (∼1 milliamp) radio-frequency quadrupole accelerator to inject 0.9 MeV deuterons into the Alcator C-Mod tokamak at MIT. We control the tokamak magnetic fields – in between plasma shots – to steer the deuterons to material surfaces where the deuterons cause high-Q nuclear reactions with low-Z isotopes ∼5 μm into the material. The induced neutrons and gamma rays are measured with scintillation detectors; energy spectra analysis provides quantitative reconstruction of surface compositions. An overview of the diagnostic technique, known as accelerator-based in situ materials surveillance (AIMS), and the first AIMS diagnostic on the Alcator C-Mod tokamak is given. Experimental validation is shown to demonstrate that an optimized deuteron beam is injected into the tokamak, that low-Z isotopes such as deuterium and boron can be quantified on the material surfaces, and that magnetic steering provides access to different measurement locations. The first AIMS analysis, which measures the relative change in deuterium at a single surface location at the end of the Alcator C-Mod FY2012 plasma campaign, is also presented.

  13. 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%.

  14. 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…

  15. 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. PMID:23359268

  16. High-Current Experiments for Accelerator-Based Neutron Capture Therapy Applications

    SciTech Connect

    Gierga, D.P.; Klinkowstein, R.E.; Hughey, B.H.; Shefer, R.E.; Yanch, J.C.; Blackburn, B.W.

    1999-06-06

    Several accelerator-based neutron capture therapy applications are under development. These applications include boron neutron capture therapy for glioblastoma multiform and boron neutron capture synovectomy (BNCS) for rheumatoid arthritis. These modalities use accelerator-based charged-particle reactions to create a suitable neutron source. Neutrons are produced using a high-current, 2-MV terminal tandem accelerator. For these applications to be feasible, high accelerator beam currents must be routinely achievable. An effort was undertaken to explore the operating regime of the accelerator in the milliampere range. In preparation for high-current operation of the accelerator, computer simulations of charged-particle beam optics were performed to establish high-current operating conditions. Herein we describe high beam current simulations and high beam current operation of the accelerator.

  17. Ensemble Manifold Rank Preserving for Acceleration-Based Human Activity Recognition.

    PubMed

    Tao, Dapeng; Jin, Lianwen; Yuan, Yuan; Xue, Yang

    2016-06-01

    With the rapid development of mobile devices and pervasive computing technologies, acceleration-based human activity recognition, a difficult yet essential problem in mobile apps, has received intensive attention recently. Different acceleration signals for representing different activities or even a same activity have different attributes, which causes troubles in normalizing the signals. We thus cannot directly compare these signals with each other, because they are embedded in a nonmetric space. Therefore, we present a nonmetric scheme that retains discriminative and robust frequency domain information by developing a novel ensemble manifold rank preserving (EMRP) algorithm. EMRP simultaneously considers three aspects: 1) it encodes the local geometry using the ranking order information of intraclass samples distributed on local patches; 2) it keeps the discriminative information by maximizing the margin between samples of different classes; and 3) it finds the optimal linear combination of the alignment matrices to approximate the intrinsic manifold lied in the data. Experiments are conducted on the South China University of Technology naturalistic 3-D acceleration-based activity dataset and the naturalistic mobile-devices based human activity dataset to demonstrate the robustness and effectiveness of the new nonmetric scheme for acceleration-based human activity recognition. PMID:25265635

  18. 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.

  19. PREFACE: 6th Workshop on Infrared Spectroscopy and Microscopy with Accelerator-Based Sources (WIRMS11)

    NASA Astrophysics Data System (ADS)

    Lupi, Stefano; Perucchi, Andrea

    2012-05-01

    This volume of Journal of Physics: Conference Series is dedicated to a subset of papers related to the work presented at the 6th edition of the international Workshop on Infrared Spectroscopy and Microscopy with Accelerator-Based Sources (WIRMS), held in Trieste, Italy, September 4-8 2011. Previous editions of the conference were held in Porquerolles (France), Lake Tahoe (USA), Rathen (Germany), Awaji (Japan), and Banff (Canada). This edition was organized and chaired by Stefano Lupi (Roma La Sapienza) and co-chaired by Andrea Perucchi (Elettra), with the support of the Italian Synchrotron Light Laboratory ELETTRA, which was honored to host the WIRMS workshop in its tenth anniversary. The 6th WIRMS edition addressed several different topics, ranging from biochemistry to strongly correlated materials, from geology to conservation science, and from forensics to the study of cometary dusts. Representatives from the infrared scientific programs at synchrotron light sources and free-electron-laser facilities. This edition was attended by 88 participants, including representatives from the infrared scientific programs at synchrotron light sources and free-electron-laser facilities, who enjoyed the stimulating scientific presentations, several detailed discussions, and the beautiful weather and scenery of the Trieste gulf. Participants came from 16 different nations and four continents, including many young scientists, six of which were supported by the organizers. There were 45 scientific talks divided in 11 sessions: Facilities, Microspectroscopy (I, II, III), Time-Resolved Spectroscopies, Extreme Conditions, Condensed Matter, Near-Field, Imaging, THz Techniques and High-Resolution Spectroscopy. 37 posters were also presented at two very lively evening poster sessions. We would like to use the opportunity of writing this preface to thank all the participants of the workshop for the very high level of their scientific contribution and for the very friendly atmosphere

  20. 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

  1. 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…

  2. 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

  3. Comparison of accelerator-based with reactor-based waste transmutation schemes

    SciTech Connect

    Sailor, W.C.; Beard, C.A.; Venneri, F.; Davidson, J.W.

    1993-12-01

    Accelerator-based transmutation of waste (ATW) systems for the destruction of commercial LWR spent fuel are compared with systems based on thermal reactors accomplish the same objectives. When the same technology is assumed for the actinide-burning aspect of the two systems, it is seen that the size of the accelerator is determined only by the choice of how many of the long-lived fission products to burn. if none are transmuted, then the accelerator is not necessary. This result is independent of the choice of fluid carrier, and whether the actinides are destroyed in an ATW system or in a separate reactor.

  4. Panorama of new generation of accelerator based short wavelength coherent light sources

    NASA Astrophysics Data System (ADS)

    Couprie, M. E.

    2015-12-01

    The newly developed intense short wavelength light sources (from Extreme Ultra-Violet (EUV) to X-rays) have open the path to the exploration of matter for revealing structures and electronic processes and for following their evolution in time. After drawing the panorama of existing accelerator based short wavelength light sources, the new trends of evolution of short wavelengths FEL are described, with some illustrations with the example of the LUNEX5 (free electron Laser a New accelerator for the Exploitation of X-ray radiation of 5th generation) demonstrator project of advanced compact Free Electron Laser.

  5. Additive effect of BPA and Gd-DTPA for application in accelerator-based neutron source.

    PubMed

    Yoshida, F; Yamamoto, T; Nakai, K; Zaboronok, A; Matsumura, A

    2015-12-01

    Because of its fast metabolism gadolinium as a commercial drug was not considered to be suitable for neutron capture therapy. We studied additive effect of gadolinium and boron co-administration using colony forming assay. As a result, the survival of tumor cells with additional 5 ppm of Gd-DTPA decreased to 1/10 compared to the cells with boron only. Using gadolinium to increase the effect of BNCT instead of additional X-ray irradiation might be beneficial, as such combination complies with the short-time irradiation regimen at the accelerator-based neutron source. PMID:26242560

  6. A co-design method for parallel image processing accelerator based on DSP and FPGA

    NASA Astrophysics Data System (ADS)

    Wang, Ze; Weng, Kaijian; Cheng, Zhao; Yan, Luxin; Guan, Jing

    2011-11-01

    In this paper, we present a co-design method for parallel image processing accelerator based on DSP and FPGA. DSP is used as application and operation subsystem to execute the complex operations, and in which the algorithms are resolving into commands. FPGA is used as co-processing subsystem for regular data-parallel processing, and operation commands and image data are transmitted to FPGA for processing acceleration. A series of experiments have been carried out, and up to a half or three quarter time is saved which supports that the proposed accelerator will consume less time and get better performance than the traditional systems.

  7. Studies of industrial emissions by accelerator-based techniques: A review of applications at CEDAD

    NASA Astrophysics Data System (ADS)

    Calcagnile, L.; Quarta, G.

    2012-04-01

    Different research activities are in progress at the Centre for Dating and Diagnostics (CEDAD), University of Salento, in the field of environmental monitoring by exploiting the potentialities given by the different experimental beam lines implemented on the 3 MV Tande-tron accelerator and dedicated to AMS (Accelerator Mass Spectrome-try) radiocarbon dating and IB A (Ion Beam Analysis). An overview of these activities is presented by showing how accelerator-based analytical techniques can be a powerful tool for monitoring the anthropogenic carbon dioxide emissions from industrial sources and for the assessment of the biogenic content in SRF (Solid Recovered Fuel) burned in WTE (Waste to Energy) plants.

  8. Tandem-ESQ for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT)

    SciTech Connect

    Kreiner, A. J.; Kwan, J. W.; Henestroza, E.; Burlon, A. A.; Di Paolo, H.; Minsky, D.; Debray, M.; Valda, A.; Somacal, H. R.

    2007-02-12

    A folded tandem, with 1.25 MV terminal voltage, combined with an ElectroStatic Quadrupole (ESQ) chain is being proposed as a machine for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT). The machine is shown to be capable of accelerating a 30 mA proton beam to 2.5 MeV. These are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the on the 7Li(p,n)7Be reaction, to perform BNCT treatment for deep seated tumors in less than an hour.

  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. Accelerator-based tests of radiation shielding properties of materials used in human space infrastructures.

    PubMed

    Lobascio, C; Briccarello, M; Destefanis, R; Faraud, M; Gialanella, G; Grossi, G; Guarnieri, V; Manti, L; Pugliese, M; Rusek, A; Scampoli, P; Durante, M

    2008-03-01

    Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel. It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation. Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris. We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum. As proxy to galactic nuclei we used 1 GeV n iron or titanium ions. Both physics and biology tests were performed. The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material. Physics tests show that its effectiveness is close (80-90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA. Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene. Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose. PMID:18301097

  11. Richard L. Greene Dissertation Award in Experimental Condensed Matter or Materials Physics Talk: Towards single atom magnets

    NASA Astrophysics Data System (ADS)

    Baumann, Susanne

    Magnetic anisotropy is a fundamental property of magnetic materials that governs the stability and directionality of their magnetization. At the atomic level, magnetic anisotropy originates from anisotropy in the orbital angular momentum (L) and the spin-orbit coupling that connects the spin moment of a magnetic atom to the spatial symmetry of its ligand field environment. Generally, the ligand field, that is necessary for the anisotropy, also quenches the orbital moment and reduces the total magnetic moment of the atom to its spin component. However, careful design of the coordination geometry of a single atom can restore the orbital moment while inducing uniaxial anisotropy, as we present here for single atoms deposited on top of a thin MgO film. Scanning tunneling spectroscopy and x-ray absorption spectroscopy measurements show a large magnetic anisotropy of 19 meV for iron and 58 meV for cobalt, as well as relaxation times of many milliseconds. These results offer a strategy, based on symmetry arguments and careful tailoring of the interaction with the environment, for the rational design of nanoscopic permanent magnets and single atom magnets.

  12. 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.

  13. Elemental analysis of concrete samples using an accelerator-based PGNAA setup

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Nagadi, M. M.; Baghabra Al-Amoudi, Omar S.

    2004-09-01

    Elemental analysis of concrete samples was carried out using an accelerator-based prompt gamma ray neutron activation analysis (PGNAA) setup. The gamma rays were produced via the capture of thermal neutron in the concrete sample. The prompt gamma ray yield was measured for 12 cm long concrete samples as a function of sample radius over a range of 6-11.5 cm radii. The optimum yield of the prompt gamma rays from the concrete sample was measured from a sample with 11.5 cm radius. The gamma ray yield was also calculated for 12 cm long concrete samples with 6-11.5 cm radius using Monte Carlo simulations. The experimental results were in excellent agreement with the calculated yield of the prompt gamma rays from the samples. Result of this study has shown the useful application of an accelerator-based PGNAA setup in elemental analysis of concrete sample. The facility can be further used to determine the chloride and sulfate concentrations in concrete samples for corrosion studies of reinforcement steel in concrete structures.

  14. Pedestrian movement analysis in transfer station corridor: Velocity-based and acceleration-based

    NASA Astrophysics Data System (ADS)

    Ji, Xiangfeng; Zhang, Jian; Hu, Yongkai; Ran, Bin

    2016-05-01

    In this paper, pedestrians are classified into aggressive and conservative ones by their temper. Aggressive pedestrians' walking through crowd in transfer station corridor is analyzed. Treating pedestrians as particles, this paper uses the modified social force model (MSFM) as the building block, where forces involve self-driving force, repulsive force and friction force. The proposed model in this paper is a discrete model combining the MSFM and cellular automata (CA) model, where the updating rules of the CA are redefined with MSFM. Due to the continuity of values generated by the MSFM, we use the fuzzy logic to discretize the continuous values into cells pedestrians can move in one step. With the observation that stimulus around pedestrians influences their acceleration directly, an acceleration-based movement model is presented, compared to the generally reviewed velocity-based movement model. In the acceleration-based model, a discretized version of kinematic equation is presented based on the acceleration discretized with fuzzy logic. In real life, some pedestrians would rather keep their desired speed and this is also mimicked in this paper, which is called inertia. Compared to the simple triangular membership function, a trapezoidal membership function and a piecewise linear membership function are used to capture pedestrians' inertia. With the trapezoidal and the piecewise linear membership function, many overlapping scenarios should be carefully handled and Dubois and Prade's four-index method is used to completely describe the relative relationship of fuzzy quantities. Finally, a simulation is constructed to demonstrate the effect of our model.

  15. JAERI R and D on accelerator-based transmutation under OMEGA program

    SciTech Connect

    Takizuka, T.; Nishida, T.; Mizumoto, M.; Yoshida, H.

    1995-09-15

    The overview of the Japanese long-term research and development program on nuclide partitioning and transmutation, called ''OMEGA,'' is presented. Under this national program, major R and D activities are being carried out at JAERI, PNC, and CRIEPI. Accelerator-based transmutation study at JAERI is focused on a dedicated transmutor with a subcritical actinide-fueled subcritical core coupled with a spallation target driven by a high intensity proton accelerator. Two types of system concept, solid system and molten-salt system, are discussed. The solid system consists of sodium-cooled tungsten target and metallic actinide fuel. The molten-salt system is fueled with molten actinide chloride that acts also as a target material. The proposed plant transmutes about 250 kg of minor actinide per year, and generates enough electricity to power its own accelerator. JAERI is proposing the development of an intense proton linear accelerator ETA with 1.5 GeV-10 mA beam for engineering tests of accelerator-based transmutation. Recent achievements in the accelerator development are described.

  16. Measuring Chern numbers in Atomic Gases: 2D and 4D Quantum Hall Physics in the Lab

    NASA Astrophysics Data System (ADS)

    Goldman, Nathan

    Optical-lattice experiments have recently succeeded in probing the geometry of 2D Bloch bands with cold neutral atoms. Beyond these local geometrical effects, which are captured by the Berry curvature, 2D Bloch bands may also display non-trivial topology, a global property captured by a topological invariant (e.g. the first Chern number). Such topological properties have dramatic consequences on the transport of non-interacting atoms, such as quantized responses whenever the bands are uniformly populated. In this talk, I will start with the first experimental demonstration of topological transport in a gas of neutral particles, which revealed the Chern number through a cold-atom analogue of quantum-Hall measurements. I will then describe how this Chern-number measurement could be extended in order to probe the topology of higher-dimensional systems. In particular, I will show how the second Chern number - an emblematic topological invariant associated with 4D Bloch bands - could be extracted from an atomic gas, using a 3D optical lattice extended by a synthetic dimension. Finally, I will describe a general scheme by which optical lattices of subwavelength spacing could be realized. This method leads to topological band structures with significantly enhanced energy scales, offering an interesting route towards the experimental realization of strongly-correlated topological states with cold atoms.

  17. Newton's Atom

    NASA Astrophysics Data System (ADS)

    Chaney, Andrea; Espinosa, James; Espinosa, James

    2006-10-01

    At the turn of the twentieth century, physicists and chemists were developing atomic models. Some of the phenomena that they had to explain were the periodic table, the stability of the atom, and the emission spectra. Niels Bohr is known as making the first modern picture that accounted for these. Unknown to much of the physics community is the work of Walter Ritz. His model explained more emission spectra and predates Bohr's work. We will fit several spectra using Ritz's magnetic model for the atom. The problems of stability and chemical periodicity will be shown to be challenges that this model has difficulty solving, but we will present some potentially useful adaptations to the Ritzian atom that can account for them.

  18. 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."

  19. Physics Division progress report for period ending September 30, 1990

    SciTech Connect

    Livingston, A.B.

    1991-03-01

    The activities of this Division continue to be concentrated in the areas of experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. The Holifield Heavy Ion Research Facility and its operation as a national user facility continued as the single largest activity within the Division. The experimental nuclear physics program continues to emphasize heavy ion studies, with much of the activity centered at the Holifield Facility. The work with heavy ions at ultrarelativistic energies continues at the CERN SPS. Studies at the Brookhaven AGS, particularly in preparation of future experiments at RHIC, have seen an increased emphasis. A major consortium has been formed to propose the design and construction of a dimuon detector as the basis for one the principal experiments for RHIC. Also included are results from the increasing effort in particle physics, including participation in the L* proposal for the SSC. The UNISOR program, since its inception, has been associated intimately with the Division and, most particularly, with the Holifield Facility. A major area of experimental research for the Division is atomic physics. This activity comprises two groups: one on accelerator-based atomic physics, centered primarily at the EN-tandem and the Holifield Facility, but extending this year to an experiment at ultrarelativistic energies at the CERN SPS; and one on atomic physics in support of fusion energy, based primarily at the ECR ion source facility. Included in this section is also a description of a new effort in multicharged ion-surface interactions, and details of a planned upgrade of the ECR source.

  20. Physics Division progress report for period ending September 30, 1984

    SciTech Connect

    Livingston, A.B.

    1985-01-01

    The research activities of the Division are centered primarily in three areas: experimental nuclear physics, experimental atomic physics, and theoretical nuclear and atomic physics. The largest of these efforts, experimental nuclear physics, is dominated by the heavy ion research program. A major responsibility under this program is the operation of the Holifield Heavy Ion Research Facility as a national user facility. During the period of this report, the facility has begun routine operation for the experimental program. The experimental atomic physics program has two components: the accelerator-based studies of basic collisional phenomena and the studies in support of the controlled fusion program. Also associated with the fusion-related studies are a plasma diagnostics program and the operation of an atomic physics data center. The theoretical physics program, both nuclear and atomic, is covered. This program has benefited this year from the success of the VAX-AP computer system and from the increase in manpower provided by the ORNL/University of Tennessee Distinguished Scientist Program. Smaller programs in applications and high-energy physics are summarized. During the period of this report, we continued to explore possible future extensions of the Holifield Facility. We retain a strong interest in a relativistic heavy-ion collider in the 10 x 10 GeV/nuclear energy range. The ideas for such a facility, described in last year's report, have been modified to utilize the HHIRF 25 MV tandem accelerator as the first stage. Finally, the report concludes with some general information on publications, Division activities, and personnel changes.

  1. 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…

  2. 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)

  3. Conceptual design of an RFQ accelerator-based neutron source for boron neutron-capture therapy

    SciTech Connect

    Wangler, T.P.; Stovall, J.E.; Bhatia, T.S.; Wang, C.K.; Blue, T.E.; Gahbauer, R.A.

    1989-01-01

    We present a conceptual design of a low-energy neutron generator for treatment of brain tumors by boron neutron capture theory (BNCT). The concept is based on a 2.5-MeV proton beam from a radio-frequency quadrupole (RFQ) linac, and the neutrons are produced by the /sup 7/Li(p,n)/sup 7/Be reaction. A liquid lithium target and modulator assembly are designed to provide a high flux of epithermal neutrons. The patient is administered a tumor-specific /sup 10/Be-enriched compound and is irradiated by the neutrons to create a highly localized dose from the reaction /sup 10/B(n,..cap alpha..)/sup 7/Li. An RFQ accelerator-based neutron source for BNCT is compact, which makes it practical to site the facility within a hospital. 11 refs., 5 figs., 1 tab.

  4. About the scheme of the infrared FEL system for the accelerator based on HF wells

    SciTech Connect

    Kabanov, V.S.; Dzergach, A.I.

    1995-12-31

    Accelerators, based on localization of plasmoids in the HF wells (RF traps) of the axially-symmetric electromagnetic field E {sub omn} in an oversized (m,n>>1) resonant system, can give accelerating gradients {approximately}100 kV/{lambda}, e.g. 10 GV/m if {lambda}=10 {mu}m. One of possible variants of HF feeding for these accelerators is based on using the powerful infrared FEL System with 2 frequencies. The corresponding FEL`s may be similar to the Los Alamos compact Advanced FEL ({lambda}{sub 1,2}{approximately}10 pm, e-beam energy {approximately}15 MeV, e-beam current {approximately}100 A). Their power is defined mainly by the HF losses in the resonant system of the supposed accelerator.

  5. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Al-Matouq, Faris A.; Khiari, F. Z.; Gondal, M. A.; Rehman, Khateeb-ur; Isab, A. A.; Raashid, M.; Dastageer, M. A.

    2013-11-01

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53-3.68, 4.51, 5.27-5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  6. Shielding design of a treatment room for an accelerator-based neutron source for BNCT

    SciTech Connect

    Evans, J.F.; Blue, T.E.

    1995-12-31

    For several years, research has been ongoing in the Ohio State University (OSU) Nuclear Engineering Program toward the development of an accelerator-based irradiation facility (ANIF) neutron source for boron neutron capture therapy (BNCT). The ANIF, which is planned to be built in a hospital, has been conceptually designed and analyzed. After Qu, an OSU researcher, determined that the shielding design of a 6-MV X-ray treatment room was inadequate to protect personnel from an accelerator neutron source operating at 30 mA, we decided to analyze and determine the shielding requirements of a treatment room for an ANIF. We determined the amount of shielding that would be sufficient to protect facility personnel from excessive radiation exposure caused by operation of the accelerator at 30 mA.

  7. Accelerator-based Neutron Fluence Standard of the National Metrology Institute of Japan

    NASA Astrophysics Data System (ADS)

    Harano, Hideki; Matsumoto, Tetsuro; Nishiyama, Jun; Uritani, Akira; Kudo, Katsuhisa

    2009-03-01

    We report the present status of the national standard on accelerator-based fast neutron fluences in Japan. Monoenergetic neutron fluence standards have been established at 144 keV, 565 keV, 5.0 MeV and 8.0 MeV by using a Van de Graaff accelerator and at 2.5 MeV and 14.8 MeV by using a Cockcroft Walton accelerator. These standards are prepared to measure the detection efficiency and the energy response of neutron sensitive devices, such as personal dosimeters and survey meters. Neutron production and absolute fluence measurement for these energies are described. We are developing a new standard in the energy region of a few tens of keV, which is also introduced here as well as our future plans.

  8. Extending PowerPack for Profiling and Analysis of High Performance Accelerator-Based Systems

    SciTech Connect

    Li, Bo; Chang, Hung-Ching; Song, Shuaiwen; Su, Chun-Yi; Meyer, Timmy; Mooring, John; Cameron, Kirk

    2014-12-01

    Accelerators offer a substantial increase in efficiency for high-performance systems offering speedups for computational applications that leverage hardware support for highly-parallel codes. However, the power use of some accelerators exceeds 200 watts at idle which means use at exascale comes at a significant increase in power at a time when we face a power ceiling of about 20 megawatts. Despite the growing domination of accelerator-based systems in the Top500 and Green500 lists of fastest and most efficient supercomputers, there are few detailed studies comparing the power and energy use of common accelerators. In this work, we conduct detailed experimental studies of the power usage and distribution of Xeon-Phi-based systems in comparison to the NVIDIA Tesla and at SandyBridge.

  9. 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.

  10. Simulations of an accelerator-based shielding experiment using the particle and heavy-ion transport code system PHITS.

    PubMed

    Sato, T; Sihver, L; Iwase, H; Nakashima, H; Niita, K

    2005-01-01

    In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS), which is based on the NMTC and MCNP for nucleon/meson and neutron transport respectively, and the JAM hadron cascade model. PHITS uses JAERI Quantum Molecular Dynamics (JQMD) and the Generalized Evaporation Model (GEM) for calculations of fission and evaporation processes, a model developed at NASA Langley for calculation of total reaction cross sections, and the SPAR model for stopping power calculations. The future development of PHITS includes better parameterization in the JQMD model used for the nucleus-nucleus reactions, and improvement of the models used for calculating total reaction cross sections, and addition of routines for calculating elastic scattering of heavy ions, and inclusion of radioactivity and burn up processes. As a part of an extensive bench marking of PHITS, we have compared energy spectra of secondary neutrons created by reactions of HZE particles with different targets, with thicknesses ranging from <1 to 200 cm. We have also compared simulated and measured spatial, fluence and depth-dose distributions from different high energy heavy ion reactions. In this paper, we report simulations of an accelerator-based shielding experiment, in which a beam of 1 GeV/n Fe-ions has passed through thin slabs of polyethylene, Al, and Pb at an acceptance angle up to 4 degrees. PMID:15934196

  11. Simulations of an accelerator-based shielding experiment using the particle and heavy-ion transport code system PHITS

    NASA Astrophysics Data System (ADS)

    Sato, T.; Sihver, L.; Iwase, H.; Nakashima, H.; Niita, K.

    In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS), which is based on the NMTC and MCNP for nucleon/meson and neutron transport respectively, and the JAM hadron cascade model. PHITS uses JAERI Quantum Molecular Dynamics (JQMD) and the Generalized Evaporation Model (GEM) for calculations of fission and evaporation processes, a model developed at NASA Langley for calculation of total reaction cross sections, and the SPAR model for stopping power calculations. The future development of PHITS includes better parameterization in the JQMD model used for the nucleus-nucleus reactions, and improvement of the models used for calculating total reaction cross sections, and addition of routines for calculating elastic scattering of heavy ions, and inclusion of radioactivity and burn up processes. As a part of an extensive bench marking of PHITS, we have compared energy spectra of secondary neutrons created by reactions of HZE particles with different targets, with thicknesses ranging from <1 to 200 cm. We have also compared simulated and measured spatial, fluence and depth-dose distributions from different high energy heavy ion reactions. In this paper, we report simulations of an accelerator-based shielding experiment, in which a beam of 1 GeV/n Fe-ions has passed through thin slabs of polyethylene, Al, and Pb at an acceptance angle up to 4°.

  12. Davisson-Germer Prize in Atomic or Surface Physics: The COLTRIMS multi-particle imaging technique-new Insight into the World of Correlation

    NASA Astrophysics Data System (ADS)

    Schmidt-Bocking, Horst

    2008-05-01

    The correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short as an atto-sec) of the correlated dynamics between electrons and nuclei has been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. Recent multiple-ionization studies will be presented and the observation of correlated electron pairs will be discussed.

  13. 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

  14. 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?

  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

    ScienceCinema

    Mark Kasevich

    2010-01-08

    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 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?

  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. 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)

  19. Greek atomic theory

    NASA Astrophysics Data System (ADS)

    Roller, Duane H. D.

    1981-03-01

    Physics began about 600 B.C. with the Ionian Greeks and reached full development within three centuries. 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.

  20. Pulse Controlled Frequency-Chirped Laser Light at Large Detuning for Use in Atomic, Molecular, and Optical Physics Experiments

    NASA Astrophysics Data System (ADS)

    Kaufman, Brian; Paltoo, Tracy; Grogan, Tanner; Wright, Matthew

    2016-05-01

    We have developed a laser system that generates a moderate frequency chirp (1 GHz in 4 ns) at a large controllable detuning (~7 GHz) using an electro-optical phase modulator in an injection-lock laser system. This system can effectively pulse the laser on timescales less than 3 ns by turning on and off the injection lock. This system can also create arbitrary frequency chirp shapes on the laser on the tens of nanosecond time scales with a cutoff frequency of 200 MHz. As a test of the laser system, we have explored excitation of a room-temperature atomic Rb gas with frequency-chirped light. We have found that our experimental results agree with the solution to the Optical Bloch equations for the same parameters.

  1. 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.

  2. Accelerator-based conversion (ABC) of weapons plutonium: Plant layout study and related design issues

    SciTech Connect

    Cowell, B.S.; Fontana, M.H.; Krakowski, R.A.; Beard, C.A.; Buksa, J.J.; Davidson, J.W.; Sailor, W.C.; Williamson, M.A.

    1995-04-01

    In preparation for and in support of a detailed R and D Plan for the Accelerator-Based Conversion (ABC) of weapons plutonium, an ABC Plant Layout Study was conducted at the level of a pre-conceptual engineering design. The plant layout is based on an adaptation of the Molten-Salt Breeder Reactor (MSBR) detailed conceptual design that was completed in the early 1070s. Although the ABC Plant Layout Study included the Accelerator Equipment as an essential element, the engineering assessment focused primarily on the Target; Primary System (blanket and all systems containing plutonium-bearing fuel salt); the Heat-Removal System (secondary-coolant-salt and supercritical-steam systems); Chemical Processing; Operation and Maintenance; Containment and Safety; and Instrumentation and Control systems. Although constrained primarily to a reflection of an accelerator-driven (subcritical) variant of MSBR system, unique features and added flexibilities of the ABC suggest improved or alternative approaches to each of the above-listed subsystems; these, along with the key technical issues in need of resolution through a detailed R&D plan for ABC are described on the bases of the ``strawman`` or ``point-of-departure`` plant layout that resulted from this study.

  3. A comparison of public datasets for acceleration-based fall detection.

    PubMed

    Igual, Raul; Medrano, Carlos; Plaza, Inmaculada

    2015-09-01

    Falls are one of the leading causes of mortality among the older population, being the rapid detection of a fall a key factor to mitigate its main adverse health consequences. In this context, several authors have conducted studies on acceleration-based fall detection using external accelerometers or smartphones. The published detection rates are diverse, sometimes close to a perfect detector. This divergence may be explained by the difficulties in comparing different fall detection studies in a fair play since each study uses its own dataset obtained under different conditions. In this regard, several datasets have been made publicly available recently. This paper presents a comparison, to the best of our knowledge for the first time, of these public fall detection datasets in order to determine whether they have an influence on the declared performances. Using two different detection algorithms, the study shows that the performances of the fall detection techniques are affected, to a greater or lesser extent, by the specific datasets used to validate them. We have also found large differences in the generalization capability of a fall detector depending on the dataset used for training. In fact, the performance decreases dramatically when the algorithms are tested on a dataset different from the one used for training. Other characteristics of the datasets like the number of training samples also have an influence on the performance while algorithms seem less sensitive to the sampling frequency or the acceleration range. PMID:26233258

  4. Materials considerations for molten salt accelerator-based plutonium conversion systems

    SciTech Connect

    DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

    1995-03-01

    Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF{sub 2} molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized.

  5. Materials considerations for molten salt accelerator-based plutonium conversion systems

    SciTech Connect

    DiStefano, J.R.; DeVan, J.H.; Keiser, J.R.; Klueh, R.L.; Eatherly, W.P.

    1995-02-01

    Accelerator-driven transmutation technology (ADTT) refers to a concept for a system that uses a blanket assembly driven by a source of neutrons produced when high-energy protons from an accelerator strike a heavy metal target. One application for such a system is called Accelerator-Based Plutonium Conversion, or ABC. Currently, the version of this concept being proposed by the Los Alamos National Laboratory features a liquid lead target material and a blanket fuel of molten fluorides that contain plutonium. Thus, the materials to be used in such a system must have, in addition to adequate mechanical strength, corrosion resistance to molten lead, corrosion resistance to molten fluoride salts, and resistance to radiation damage. In this report the corrosion properties of liquid lead and the LiF-BeF{sub 2} molten salt system are reviewed in the context of candidate materials for the above application. Background information has been drawn from extensive past studies. The system operating temperature, type of protective environment, and oxidation potential of the salt are shown to be critical design considerations. Factors such as the generation of fission products and transmutation of salt components also significantly affect corrosion behavior, and procedures for inhibiting their effects are discussed. In view of the potential for extreme conditions relative to neutron fluxes and energies that can occur in an ADTT, a knowledge of radiation effects is a most important factor. Present information for potential materials selections is summarized.

  6. Fuel retention measurements in Alcator C-Mod using accelerator-based in situ materials surveillance

    NASA Astrophysics Data System (ADS)

    Hartwig, Zachary S.; Barnard, Harold S.; Sorbom, Brandon N.; Lanza, Richard C.; Lipschultz, Bruce; Stahle, Peter W.; Whyte, Dennis G.

    2015-08-01

    This paper presents the first in situ time- and space-resolved measurements of deuterium (D) fuel retention in plasma-facing component (PFC) surfaces using Accelerator-based In-situ Materials Surveillance (AIMS) on the Alcator C-Mod tokamak. AIMS is a novel in situ materials diagnostic technique based on the spectroscopic analysis of nuclear reaction products induced in PFC surfaces using an ∼MeV beam of deuterons from a compact linear accelerator in between plasma shots. AIMS measurements of D retention on inner wall PFCs were acquired during diverted and limited plasma operations and during wall conditioning experiments. Intershot measurements demonstrate the local erosion and codeposition of boron films on PFC surfaces with a constant D / B ratio. This is consistent with previous results suggesting that D codeposition with boron is insufficient to account for the net retention observed in Alcator C-Mod. Changes in deuterium concentration during boronization, electron cyclotron and glow cleanings were also measured.

  7. Characterisation of an accelerator-based neutron source for BNCT versus beam energy

    NASA Astrophysics Data System (ADS)

    Agosteo, S.; Curzio, G.; d'Errico, F.; Nath, R.; Tinti, R.

    2002-01-01

    Neutron capture in 10B produces energetic alpha particles that have a high linear energy transfer in tissue. This results in higher cell killing and a higher relative biological effectiveness compared to photons. Using suitably designed boron compounds which preferentially localize in cancerous cells instead of healthy tissues, boron neutron capture therapy (BNCT) has the potential of providing a higher tumor cure rate within minimal toxicity to normal tissues. This clinical approach requires a thermal neutron source, generally a nuclear reactor, with a fluence rate sufficient to deliver tumorcidal doses within a reasonable treatment time (minutes). Thermal neutrons do not penetrate deeply in tissue, therefore BNCT is limited to lesions which are either superficial or otherwise accessible. In this work, we investigate the feasibility of an accelerator-based thermal neutron source for the BNCT of skin melanomas. The source was designed via MCNP Monte Carlo simulations of the thermalization of a fast neutron beam, generated by 7 MeV deuterons impinging on a thick target of beryllium. The neutron field was characterized at several deuteron energies (3.0-6.5 MeV) in an experimental structure installed at the Van De Graaff accelerator of the Laboratori Nazionali di Legnaro, in Italy. Thermal and epithermal neutron fluences were measured with activation techniques and fast neutron spectra were determined with superheated drop detectors (SDD). These neutron spectrometry and dosimetry studies indicated that the fast neutron dose is unacceptably high in the current design. Modifications to the current design to overcome this problem are presented.

  8. High-power liquid-lithium target prototype for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Bisyakoev, M; Eliyahu, I; Feinberg, G; Hazenshprung, N; Kijel, D; Nagler, A; Silverman, I

    2011-12-01

    A prototype of a compact Liquid-Lithium Target (LiLiT), which will possibly constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals, was built. The LiLiT setup is presently being commissioned at Soreq Nuclear Research Center (SNRC). The liquid-lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power generated using a high-intensity proton beam (>10 kW), necessary for sufficient neutron flux. In off-line circulation tests, the liquid-lithium loop generated a stable lithium jet at high velocity, on a concave supporting wall; the concept will first be tested using a high-power electron beam impinging on the lithium jet. High intensity proton beam irradiation (1.91-2.5 MeV, 2-4 mA) will take place at Soreq Applied Research Accelerator Facility (SARAF) superconducting linear accelerator currently in construction at SNRC. Radiological risks due to the (7)Be produced in the reaction were studied and will be handled through a proper design, including a cold trap and appropriate shielding. A moderator/reflector assembly is planned according to a Monte Carlo simulation, to create a neutron spectrum and intensity maximally effective to the treatment and to reduce prompt gamma radiation dose risks. PMID:21459008

  9. An accelerator-based epithermal photoneutron source for boron neutron capture therapy

    SciTech Connect

    Mitchell, H.E.

    1996-04-01

    Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10{sup 7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF{sub 3} composite and a stacked Al/Teflon design) at various incident electron energies.

  10. Accelerator-Based Biological Irradiation Facility Simulating Neutron Exposure from an Improvised Nuclear Device.

    PubMed

    Xu, Yanping; Randers-Pehrson, Gerhard; Turner, Helen C; Marino, Stephen A; Geard, Charles R; Brenner, David J; Garty, Guy

    2015-10-01

    We describe here an accelerator-based neutron irradiation facility, intended to expose blood or small animals to neutron fields mimicking those from an improvised nuclear device at relevant distances from the epicenter. Neutrons are generated by a mixed proton/deuteron beam on a thick beryllium target, generating a broad spectrum of neutron energies that match those estimated for the Hiroshima bomb at 1.5 km from ground zero. This spectrum, dominated by neutron energies between 0.2 and 9 MeV, is significantly different from the standard reactor fission spectrum, as the initial bomb spectrum changes when the neutrons are transported through air. The neutron and gamma dose rates were measured using a custom tissue-equivalent gas ionization chamber and a compensated Geiger-Mueller dosimeter, respectively. Neutron spectra were evaluated by unfolding measurements using a proton-recoil proportional counter and a liquid scintillator detector. As an illustration of the potential use of this facility we present micronucleus yields in single divided, cytokinesis-blocked human peripheral lymphocytes up to 1.5 Gy demonstrating 3- to 5-fold enhancement over equivalent X-ray doses. This facility is currently in routine use, irradiating both mice and human blood samples for evaluation of neutron-specific biodosimetry assays. Future studies will focus on dose reconstruction in realistic mixed neutron/photon fields. PMID:26414507

  11. Radiation shielding and patient organ dose study for an accelerator- based BNCT Facility at LBNL

    SciTech Connect

    Costes, S.V.; Vujic, J.; Donahue, R.J.

    1996-10-24

    This study considers the radiation safety aspects of several designs discussed in a previous report of an accelerator-based source of neutrons, based on the [sup 7]Li(p,n) reaction, for a Boron Neutron Capture Therapy (BNCT) Facility at Lawrence Berkeley National Laboratory (LBNL). determines the optimal radiation shield thicknesses for the patient treatment room. Since this is an experimental facility no moderator or reflector is considered in the bulk wall shield design. This will allow the flexibility of using any postulated moderator/reflector design and assumes sufficient shielding even in the absence of a moderator/reflector. In addition the accelerator is assumed to be capable of producing 100 mA of 2.5 MeV proton beam current. The addition of 1% and 2% [sup 10]B (by weight) to the concrete is also investigated. The second part of this paper determines the radiation dose to the major organs of a patient during a treatment. Simulations use the MIRD 5 anthropomorphic phantom to calculate organ doses from a 20 mA proton beam assuming various envisioned moderator/reflector in place. Doses are tabulated by component and for a given uniform [sup 10]B loading in all organs. These are presented in for a BeO moderator and for an Al/AlF[sub 3] moderator. Dose estimates for different [sup 10]B loadings may be scaled.

  12. Design study of double-layer beam trajectory accelerator based on the Rhodotron structure

    NASA Astrophysics Data System (ADS)

    Jabbari, Iraj; Poursaleh, Ali Mohammad; Khalafi, Hossein

    2016-08-01

    In this paper, the conceptual design of a new structure of industrial electron accelerator based on the Rhodotron accelerator is presented and its properties are compared with those of Rhodotron-TT200 accelerator. The main goal of this study was to reduce the power of RF system of accelerator at the same output electron beam energy. The main difference between the new accelerator structure with the Rhodotron accelerator is the length of the coaxial cavity that is equal to the wavelength at the resonant frequency. Also two sets of bending magnets were used around the acceleration cavity in two layers. In the new structure, the beam crosses several times in the coaxial cavity by the bending magnets around the cavity at the first layer and then is transferred to the second layer using the central bending magnet. The acceleration process in the second layer is similar to the first layer. Hence, the energy of the electron beam will be doubled. The electrical power consumption of the RF system and magnet system were calculated and simulated for the new accelerator structure and TT200. Comparing the calculated and simulated results of the TT200 with those of experimental results revealed good agreement. The results showed that the overall electrical power consumption of the new accelerator structure was less than that of the TT200 at the same energy and power of the electron beam. As such, the electrical efficiency of the new structure was improved.

  13. Comparison between CARIBIC Aerosol Samples Analysed by Accelerator-Based Methods and Optical Particle Counter Measurements

    NASA Astrophysics Data System (ADS)

    Martinsson, B. G.; Friberg, J.; Andersson, S. M.; Weigelt, A.; Hermann, M.; Assmann, D.; Voigtländer, J.; Brenninkmeijer, C. A. M.; van Velthoven, P. J. F.; Zahn, A.

    2014-08-01

    Inter-comparison of results from two kinds of aerosol systems in the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on a Instrument Container) passenger aircraft based observatory, operating during intercontinental flights at 9-12 km altitude, is presented. Aerosol from the lowermost stratosphere (LMS), the extra-tropical upper troposphere (UT) and the tropical mid troposphere (MT) were investigated. Aerosol particle volume concentration measured with an optical particle counter (OPC) is compared with analytical results of the sum of masses of all major and several minor constituents from aerosol samples collected with an impactor. Analyses were undertaken with the following accelerator-based methods: particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA). Data from 48 flights during 1 year are used, leading to a total of 106 individual comparisons. The ratios of the particle volume from the OPC and the total mass from the analyses were in 84% within a relatively narrow interval. Data points outside this interval are connected with inlet-related effects in clouds, large variability in aerosol composition, particle size distribution effects and some cases of non-ideal sampling. Overall, the comparison of these two CARIBIC measurements based on vastly different methods show good agreement, implying that the chemical and size information can be combined in studies of the MT/UT/LMS aerosol.

  14. Comparison between CARIBIC aerosol samples analysed by accelerator-based methods and optical particle counter measurements

    NASA Astrophysics Data System (ADS)

    Martinsson, B. G.; Friberg, J.; Andersson, S. M.; Weigelt, A.; Hermann, M.; Assmann, D.; Voigtländer, J.; Brenninkmeijer, C. A. M.; van Velthoven, P. J. F.; Zahn, A.

    2014-04-01

    Inter-comparison of results from two kinds of aerosol systems in the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) passenger aircraft based observatory, operating during intercontinental flights at 9-12 km altitude, is presented. Aerosol from the lowermost stratosphere (LMS), the extra-tropical upper troposphere (UT) and the tropical mid troposphere (MT) were investigated. Aerosol particle volume concentration measured with an optical particle counter (OPC) is compared with analytical results of the sum of masses of all major and several minor constituents from aerosol samples collected with an impactor. Analyses were undertaken with accelerator-based methods particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA). Data from 48 flights during one year are used, leading to a total of 106 individual comparisons. The ratios of the particle volume from the OPC and the total mass from the analyses were in 84% within a relatively narrow interval. Data points outside this interval are connected with inlet-related effects in clouds, large variability in aerosol composition, particle size distribution effects and some cases of non-ideal sampling. Overall, the comparison of these two CARIBIC measurements based on vastly different methods show good agreement, implying that the chemical and size information can be combined in studies of the MT/UT/LMS aerosol.

  15. Doppler Broadening Analysis of Steel Specimens Using Accelerator Based In Situ Pair Production

    SciTech Connect

    Makarashvili, V.; Wells, D. P.; Roy, A. K.

    2009-03-10

    Positron Annihilation Spectroscopy (PAS) techniques can be utilized as a sensitive probe of defects in materials. Studying these microscopic defects is very important for a number of industries in order to predict material failure or structural integrity. We have been developing gamma-induced pair-production techniques to produce positrons in thick samples ({approx}4-40 g/cm{sup 2}, or {approx}0.5-5 cm in steel). These techniques are called 'Accelerator-based Gamma-induced Positron Annihilation Spectroscopy'(AG-PAS). We have begun testing the capabilities of this technique for imaging of defect densities in thick structural materials. As a first step, a linear accelerator (LINAC) was employed to produce photon beams by stopping 15 MeV electrons in a 1 mm thick tungsten converter. The accelerator is capable of operating with 30-60 ns pulse width, up to 200 mA peak current at 1 kHz repetition rate. The highly collimated bremsstrahlung beam impinged upon our steel tensile specimens, after traveling through a 1.2 m thick concrete wall. Annihilation radiation was detected by a well-shielded and collimated high-purity germanium detector (HPGe). Conventional Doppler broadening spectrometry (DBS) was performed to determine S, W and T parameters for our samples.

  16. Experimental dosimetry and beam evaluation in a phantom for near lithium threshold accelerator based BNCT

    NASA Astrophysics Data System (ADS)

    Kudchadker, R. J.; Lee, C. L.; Harker, Y. D.; Harmon, F.

    1999-06-01

    Current accelerator-based neutron source concepts for boron neutron capture therapy (BNCT) are centered on the lithium (p,n) reaction. The near lithium threshold source concept uses proton energies ≲100 keV above the reaction threshold energy (1.88 MeV). For deeply seated brain tumors, epithermal (1 eV to 10 keV) neutrons are needed to penetrate the skull cap and subsequently thermalize at the tumor location. All BNCT neutron sources inherently have thermal, fast neutron and gamma-ray contamination. In order to quantify the thermal neutron component, a cylindrical acrylic head phantom has been constructed to simulate the patient's head and neck. BF3 proportional counters have been used to determine the thermal neutron flux (boron dose). The thermal neutron flux component has been compared with Monte Carlo N-Particle (MCNP) code calculations. Our results indicate a good comparison between the MCNP code calculations and the benchmark experiments performed. The results also indicate that the near threshold neutron concept is competitive with other BNCT neutron sources.

  17. Experimental dosimetry and beam evaluation in a phantom for near lithium threshold accelerator based BNCT

    SciTech Connect

    Kudchadker, R. J.; Harmon, F.; Lee, C. L.; Harker, Y. D.

    1999-06-10

    Current accelerator-based neutron source concepts for boron neutron capture therapy (BNCT) are centered on the lithium (p,n) reaction. The near lithium threshold source concept uses proton energies < or approx. 100 keV above the reaction threshold energy (1.88 MeV). For deeply seated brain tumors, epithermal (1 eV to 10 keV) neutrons are needed to penetrate the skull cap and subsequently thermalize at the tumor location. All BNCT neutron sources inherently have thermal, fast neutron and gamma-ray contamination. In order to quantify the thermal neutron component, a cylindrical acrylic head phantom has been constructed to simulate the patient's head and neck. BF{sub 3} proportional counters have been used to determine the thermal neutron flux (boron dose). The thermal neutron flux component has been compared with Monte Carlo N-Particle (MCNP) code calculations. Our results indicate a good comparison between the MCNP code calculations and the benchmark experiments performed. The results also indicate that the near threshold neutron concept is competitive with other BNCT neutron sources.

  18. Designing accelerator-based epithermal neutron beams for boron neutron capture therapy

    SciTech Connect

    Bleuel, D.L.; Donahue, R.J.; Ludewigt, B.A.; Vujic, J.

    1998-09-01

    The {sup 7}Li(p,n){sup 7}Be reaction has been investigated as an accelerator-driven neutron source for proton energies between 2.1 and 2.6 MeV. Epithermal neutron beams shaped by three moderator materials, Al/AlF{sub 3}, {sup 7}LiF, and D{sub 2}O, have been analyzed and their usefulness for boron neutron capture therapy (BNCT) treatments evaluated. Radiation transport through the moderator assembly has been simulated with the Monte Carlo {ital N}-particle code (MCNP). Fluence and dose distributions in a head phantom were calculated using BNCT treatment planning software. Depth-dose distributions and treatment times were studied as a function of proton beam energy and moderator thickness. It was found that an accelerator-based neutron source with Al/AlF{sub 3} or {sup 7}LiF as moderator material can produce depth-dose distributions superior to those calculated for a previously published neutron beam design for the Brookhaven Medical Research Reactor, achieving up to {approximately}50{percent} higher doses near the midline of the brain. For a single beam treatment, a proton beam current of 20 mA, and a {sup 7}LiF moderator, the treatment time was estimated to be about 40 min. The tumor dose deposited at a depth of 8 cm was calculated to be about 21 Gy-Eq. {copyright} {ital 1998 American Association of Physicists in Medicine.}

  19. Accelerator-based trace element analysis of foods and agriculture products

    NASA Astrophysics Data System (ADS)

    Lagunas-Solar, Manuel C.; Piña U, Cecilia; Solís, Corina; Mireles, Alibech

    2008-05-01

    An accelerator-based analytical method for measuring trace elements in foods and agricultural products was developed, optimized, validated and compared using reference standards. The method's initial phase is a new, rapid and effective digestion process of a small mass analyte in an aqueous media containing H2O2. Digestion is initiated by radicals formed in water with pulsed UV (PUV) induced (laser) photolysis, which rapidly react with organic matter. After digestion, trace metals are pre-concentrated as carbamates and deposited as thin targets onto Teflon filters. Conventional particle induced X-ray emission (PIXE) or X-ray fluorescence (XRF) methods are then used to analyze elements in the sample. When foods and other agricultural commodities (i.e., soils, feeds) are analyzed, the combined method named pulsed UV (PUV)/PIXE results in enhanced detection of trace elements such as Fe, Co, Ni, Cu, Zn and Pb at ∼1 mg/kg (1 ppm) levels, without lengthy, acid-based digestions. It provides improvements in digestion kinetics and processing time enhancing analytical sensitivity and element recovery. Precision and recovery yields were confirmed with food reference standards. The analysis of edible foods from contaminated agricultural areas is also reported.

  20. Precisely detecting atomic position of atomic intensity images.

    PubMed

    Wang, Zhijun; Guo, Yaolin; Tang, Sai; Li, Junjie; Wang, Jincheng; Zhou, Yaohe

    2015-03-01

    We proposed a quantitative method to detect atomic position in atomic intensity images from experiments such as high-resolution transmission electron microscopy, atomic force microscopy, and simulation such as phase field crystal modeling. The evaluation of detection accuracy proves the excellent performance of the method. This method provides a chance to precisely determine atomic interactions based on the detected atomic positions from the atomic intensity image, and hence to investigate the related physical, chemical and electrical properties. PMID:25544105

  1. Accelerator-Based Studies of Heavy Ion Interactions Relevant to Space Biomedicine

    NASA Technical Reports Server (NTRS)

    Miller, J.; Heilbronn, L.; Zeitlin, C.

    1999-01-01

    Evaluation of the effects of space radiation on the crews of long duration space missions must take into account the interactions of high energy atomic nuclei in spacecraft and planetary habitat shielding and in the bodies of the astronauts. These heavy ions (i.e. heavier than hydrogen), while relatively small in number compared to the total galactic cosmic ray (GCR) charged particle flux, can produce disproportionately large effects by virtue of their high local energy deposition: a single traversal by a heavy charged particle can kill or, what may be worse, severely damage a cell. Research into the pertinent physics and biology of heavy ion interactions has consequently been assigned a high priority in a recent report by a task group of the National Research Council. Fragmentation of the incident heavy ions in shielding or in the human body will modify an initially well known radiation field and thereby complicate both spacecraft shielding design and the evaluation of potential radiation hazards. Since it is impractical to empirically test the radiation transport properties of each possible shielding material and configuration, a great deal of effort is going into the development of models of charged particle fragmentation and transport. Accurate nuclear fragmentation cross sections (probabilities), either in the form of measurements with thin targets or theoretical calculations, are needed for input to the transport models, and fluence measurements (numbers of fragments produced by interactions in thick targets) are needed both to validate the models and to test specific shielding materials and designs. Fluence data are also needed to characterize the incident radiation field in accelerator radiobiology experiments. For a number of years, nuclear fragmentation measurements at GCR-like energies have been carried out at heavy ion accelerators including the LBL Bevalac, Saturne (France), the Synchrophasotron and Nuklotron (Dubna, Russia), SIS-18 (GSI, Germany), the

  2. Emissive properties of xenon ions from a laser-produced plasma in the 100-140 Å spectral range: Atomic-physics analysis of the experimental data

    NASA Astrophysics Data System (ADS)

    Gilleron, F.; Poirier, M.; Blenski, T.; Schmidt, M.; Ceccotti, T.

    2003-08-01

    In order to design extreme ultraviolet (EUV) sources for nanolithography, xenon EUV emission has been experimentally studied in a plasma generated by the interaction of a high-power laser with a droplet jet. A theoretical model assuming that the resulting plasma is optically thick allows one to find the distribution of the relevant ions and transitions involved in the emission process. Atomic physics computations are performed using the HULLAC code to give a detailed account of the transitions involved. The importance of 4p-4d, 4d-4f, and 4d-5p transitions is stressed, as well as the need for configuration-interaction treatment of the Δn=0 transitions. Comparisons of a modeled local thermodynamical equilibrium spectrum with experiment provides qualitative agreement and permits an estimate of the plasma temperature, density, and dimensions.

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

    PubMed Central

    2014-01-01

    Summary 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. PMID:25383277

  4. FTICR/MS studies of gas-phase actinide ion reactions: fundamental chemical and physical properties of atomic and molecular actinide ions and neutrals

    NASA Astrophysics Data System (ADS)

    Gibson, J. K.; Haire, R. G.; Marçalo, J.; Santos, M.; Leal, J. P.; Pires de Matos, A.; Tyagi, R.; Mrozik, M. K.; Pitzer, R. M.; Bursten, B. E.

    2007-10-01

    Fundamental aspects of the chemical and physical properties of atomic and molecular actinide ions and neutrals are being examined by Fourier transform ion cyclotron resonance mass spectrometry (FTICR/MS). To date, gas-phase reactivity studies of bare and ligated An+ and An2+ ions, where An = Th, Pa, U, Np, Pu, Am, and Cm, with oxidants and with hydrocarbons have been performed. Among the information that has been deduced from these studies are thermodynamic properties of neutral and ionic actinide oxide molecules and the role of the 5f electrons in actinide chemistry. Parallel theoretical studies of selected actinide molecular ions have also been carried out to substantiate the interpretation of the experimental observations.

  5. Laser-plasma accelerators-based high energy radiation femtochemistry and spatio-temporal radiation biomedicine

    NASA Astrophysics Data System (ADS)

    Gauduel, Y. A.; Lundh, O.; Martin, M. T.; Malka, V.

    2012-06-01

    The innovating advent of powerful TW laser sources (~1019 W cm-z) and laser-plasma interactions providing ultra-short relativistic particle beams (electron, proton) in the MeV domain open exciting opportunities for the simultaneous development of high energy radiation femtochemistry (HERF) and ultrafast radiation biomedicine. Femtolysis experiments (Femtosecond radiolysis) of aqueous targets performed with relativistic electron bunches of 2.5-15 MeV give new insights on transient physicochemical events that take place in the prethermal regime of confined ionization tracks. Femtolysis studies emphasize the pre-eminence of ultra-fast quantum effects in the temporal range 10-14 - 10-11 s. The most promising advances of HERF concern the quantification of ultrafast sub-nanometric biomolecular damages (bond weakening and bond breaking) in the radial direction of a relativistic particle beam. Combining ultra-short relativistic particle beams and near-infrared spectroscopic configurations, laser-plasma accelerators based high energy radiation femtochemistry foreshadows the development of real-time radiation chemistry in the prethermal regime of nascent ionisation clusters. These physico-chemical advances would be very useful for future developments in biochemically relevant environments (DNA, proteins) and in more complex biological systems such as living cells. The first investigation of single and multiple irradiation shots performed at high energy level (90 MeV) and very high dose rate, typically 1013 Gy s-1, demonstrates that measurable assessments of immediate and reversible DNA damage can be explored at single cell level. Ultrafast in vivo irradiations would permit the development of bio-nanodosimetry on the time scale of molecular motions, i.e. angstrom or sub-angstrom displacements and open new perspectives in the emerging domain of ultrafast radiation biomedicine such as pulsed radiotherapy.

  6. Characterizing a Model of Coronal Heating and Solar Wind Acceleration Based on Wave Turbulence.

    NASA Astrophysics Data System (ADS)

    Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M.

    2014-12-01

    Understanding the nature of coronal heating and solar wind acceleration is a key goal in solar and heliospheric research. While there have been many theoretical advances in both topics, including suggestions that they may be intimately related, the inherent scale coupling and complexity of these phenomena limits our ability to construct models that test them on a fundamental level for realistic solar conditions. At the same time, there is an ever increasing impetus to improve our spaceweather models, and incorporating treatments for these processes that capture their basic features while remaining tractable is an important goal. With this in mind, I will give an overview of our exploration of a wave-turbulence driven (WTD) model for coronal heating and solar wind acceleration based on low-frequency Alfvénic turbulence. Here we attempt to bridge the gap between theory and practical modeling by exploring this model in 1D HD and multi-dimensional MHD contexts. The key questions that we explore are: What properties must the model possess to be a viable model for coronal heating? What is the influence of the magnetic field topology (open, closed, rapidly expanding)? And can we simultaneously capture coronal heating and solar wind acceleration with such a quasi-steady formulation? Our initial results suggest that a WTD based formulation performs adequately for a variety of solar and heliospheric conditions, while significantly reducing the number of free parameters when compared to empirical heating and solar wind models. The challenges, applications, and future prospects of this type of approach will also be discussed.

  7. High neutronic efficiency, low current targets for accelerator-based BNCT applications

    SciTech Connect

    Powell, J.R.; Ludewig, H.; Todosow, M.

    1998-08-01

    The neutronic efficiency of target/filters for accelerator-based BNCT applications is measured by the proton current required to achieve a desirable neutron current at the treatment port (10{sup 9} n/cm{sup 2}/s). In this paper the authors describe two possible targeyt/filter concepts wihch minimize the required current. Both concepts are based on the Li-7 (p,n)Be-7 reaction. Targets that operate near the threshold energy generate neutrons that are close tothe desired energy for BNCT treatment. Thus, the filter can be extremely thin ({approximately} 5 cm iron). However, this approach has an extremely low neutron yield (n/p {approximately} 1.0({minus}6)), thus requiring a high proton current. The proposed solutino is to design a target consisting of multiple extremely thin targets (proton energy loss per target {approximately} 10 keV), and re-accelerate the protons between each target. Targets operating at ihgher proton energies ({approximately} 2.5 MeV) have a much higher yield (n/p {approximately} 1.0({minus}4)). However, at these energies the maximum neutron energy is approximately 800 keV, and thus a neutron filter is required to degrade the average neutron energy to the range of interest for BNCT (10--20 keV). A neutron filter consisting of fluorine compounds and iron has been investigated for this case. Typically a proton current of approximately 5 mA is required to generate the desired neutron current at the treatment port. The efficiency of these filter designs can be further increased by incorporating neutron reflectors that are co-axial with the neutron source. These reflectors are made of materials which have high scattering cross sections in the range 0.1--1.0 MeV.

  8. Global operators for delta functions - Extension to scattering states and the inclusion of spin. [in atomic physics

    NASA Technical Reports Server (NTRS)

    Sucher, J.; Drachman, R. J.

    1979-01-01

    The paper presents an extension of the identities of Hiller, Sucher, and Feinberg for the evaluation of bound-state matrix elements of delta function operators, to scattering states. Attention is given to the technical difficulties encountered in the application of the scattering-state identities and how they can be overcome, including infrared singularities which arise if Coulomb forces are present and the velocity of the incident particle is small. In addition, both the scattering and bound-state identities are generalized to include spin-dependent contact interactions and spin-dependent Hamiltonians. Finally, it is stressed that the identities can be used to improve the accuracy of calculations of interest for diverse physical phenomena, ranging from positron annihilation to hyperfine structure.

  9. Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  10. On isocentre adjustment and quality control in linear accelerator based radiosurgery with circular collimators and room lasers

    NASA Astrophysics Data System (ADS)

    Treuer, H.; Hoevels, M.; Luyken, K.; Gierich, A.; Kocher, M.; Müller, R.-P.; Sturm, V.

    2000-08-01

    We have developed a densitometric method for measuring the isocentric accuracy and the accuracy of marking the isocentre position for linear accelerator based radiosurgery with circular collimators and room lasers. Isocentric shots are used to determine the accuracy of marking the isocentre position with room lasers and star shots are used to determine the wobble of the gantry and table rotation movement, the effect of gantry sag, the stereotactic collimator alignment, and the minimal distance between gantry and table rotation axes. Since the method is based on densitometric measurements, beam spot stability is implicitly tested. The method developed is also suitable for quality assurance and has proved to be useful in optimizing isocentric accuracy. The method is simple to perform and only requires a film box and film scanner for instrumentation. Thus, the method has the potential to become widely available and may therefore be useful in standardizing the description of linear accelerator based radiosurgical systems.

  11. Analysis of accelerator based neutron spectra for BNCT using proton recoil spectroscopy

    SciTech Connect

    Wielopolski, L.; Ludewig, H.; Powell, J.R.; Raparia, D.; Alessi, J.G.; Lowenstein, D.I.

    1999-03-01

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase 1/2 clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra, alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

  12. ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

    SciTech Connect

    WIELOPOLSKI,L.; LUDEWIG,H.; POWELL,J.R.; RAPARIA,D.; ALESSI,J.G.; LOWENSTEIN,D.I.

    1998-11-06

    Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this modality in a hospital environment. For example, accelerator based neutron sources offer the possibility of tailoring the neutron beams, in terms of improved depth-dose distributions, to the individual and offer, with relative ease, the capability of modifying the neutron beam energy and port size. In previous work new concepts for compact accelerator/target configuration were published. In this work, using the Van de Graaff accelerator the authors have explored different materials for filtering and reflecting neutron beams produced by irradiating a thick Li target with 1.8 to 2.5 MeV proton beams. However, since the yield and the maximum neutron energy emerging from the Li-7(p,n)Be-7 reaction increase with increase in the proton beam energy, there is a need for optimization of the proton energy versus filter and shielding requirements to obtain the desired epithermal neutron beam. The MCNP-4A computer code was used for the initial design studies that were verified with benchmark

  13. A low emittance and high efficiency visible light photocathode for high brightness accelerator-based X-ray light sources

    SciTech Connect

    Vecchione, T.; Ben-Zvi, I.; Dowell, D.H.; Feng, J.; Rao, T.; Smedley, J.; Wan, W.; Padmore, H.A.

    2011-07-21

    Free-electron lasers and energy recovery linacs represent a new generation of ultra-high brightness electron accelerator based x-ray sources. Photocathodes are a critical performance-limiting component of these systems. Here, we describe the development of photocathodes based on potassium-cesium-antimonide that satisfy many of the key requirements of future light sources, such as robustness, high quantum efficiency when excited with visible light, and low transverse emittance.

  14. A low emittance and high efficiency visible light photocathode for high brightness accelerator-based X-ray light sources

    SciTech Connect

    Vecchione, T.; Feng, J.; Wan, W.; Padmore, H. A.; Ben-Zvi, I.; Dowell, D. H.; Rao, T.; Smedley, J.

    2011-07-18

    Free-electron lasers and energy recovery linacs represent a new generation of ultra-high brightness electron accelerator based x-ray sources. Photocathodes are a critical performance-limiting component of these systems. Here, we describe the development of photocathodes based on potassium-cesium-antimonide that satisfy many of the key requirements of future light sources, such as robustness, high quantum efficiency when excited with visible light, and low transverse emittance.

  15. Linear Accelerator-Based Intensity-Modulated Total Marrow Irradiation Technique for Treatment of Hematologic Malignancies: A Dosimetric Feasibility Study

    SciTech Connect

    Yeginer, Mete; Roeske, John C.; Radosevich, James A.; Aydogan, Bulent

    2011-03-15

    Purpose: To investigate the dosimetric feasibility of linear accelerator-based intensity-modulated total marrow irradiation (IM-TMI) in patients with hematologic malignancies. Methods and Materials: Linear accelerator-based IM-TMI treatment planning was performed for 9 patients using the Eclipse treatment planning system. The planning target volume (PTV) consisted of all the bones in the body from the head to the mid-femur, except for the forearms and hands. Organs at risk (OAR) to be spared included the lungs, heart, liver, kidneys, brain, eyes, oral cavity, and bowel and were contoured by a physician on the axial computed tomography images. The three-isocenter technique previously developed by our group was used for treatment planning. We developed and used a common dose-volume objective method to reduce the planning time and planner subjectivity in the treatment planning process. Results: A 95% PTV coverage with the 99% of the prescribed dose of 12 Gy was achieved for all nine patients. The average dose reduction in OAR ranged from 19% for the lungs to 68% for the lenses. The common dose-volume objective method decreased the planning time by an average of 35% and reduced the inter- and intra- planner subjectivity. Conclusion: The results from the present study suggest that the linear accelerator-based IM-TMI technique is clinically feasible. We have demonstrated that linear accelerator-based IM-TMI plans with good PTV coverage and improved OAR sparing can be obtained within a clinically reasonable time using the common dose-volume objective method proposed in the present study.

  16. Viewing minerals, atom by atom

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    With state-of-the-art technology supported by scissors and bungy cords, Earth scientists are beginning to look at mineral surfaces and mineral-fluid interactions on an atomic scale.The instrument that can provide such a detailed view is the scanning tunneling microscope (STM), which made a great theoretical and practical splash when it was introduced in 1981 by Gerd Binnig and Heinrich Rohrer, physicists at IBM's laboratory in Zurich. They won a Nobel Prize in Physics for their work 5 years later.

  17. Electron-Beam Atomic Spectroscopy for In Situ Measurements of Melt Composition for Refractory Metals: Analysis of Fundamental Physics and Plasma Models

    NASA Astrophysics Data System (ADS)

    Gasper, Paul Joseph; Apelian, Diran

    2015-04-01

    Electron-beam (EB) melting is used for the processing of refractory metals, such as Ta, Nb, Mo, and W. These metals have high value and are critical to many industries, including the semiconductor, aerospace, and nuclear industries. EB melting can also purify secondary feedstock, enabling the recovery and recycling of these materials. Currently, there is no method for measuring melt composition in situ during EB melting. Optical emission spectroscopy of the plasma generated by EB impact with vapor above the melt, a technique here termed electron-beam atomic spectroscopy, can be used to measure melt composition in situ, allowing for analysis of melt dynamics, facilitating improvement of EB melting processes and aiding recycling and recovery of these critical and high-value metals. This paper reviews the physics of the plasma generation by EB impact by characterizing the densities and energies of electrons, ions, and neutrals, and describing the interactions between them. Then several plasma models are introduced and their suitability to this application analyzed. Lastly, a potential method for calibration-free composition measurement is described and the challenges for implementation addressed.

  18. Future hadron physics facilities at Fermilab

    SciTech Connect

    Appel, Jeffrey A.; /Fermilab

    2004-12-01

    Fermilab's hadron physics research continues in all its accelerator-based programs. These efforts will be identified, and the optimization of the Fermilab schedules for physics will be described. In addition to the immediate plans, the Fermilab Long Range Plan will be cited, and the status and potential role of a new proton source, the Proton Driver, is described.

  19. 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

  20. Application of an ultraminiature thermal neutron monitor for irradiation field study of accelerator-based neutron capture therapy

    PubMed Central

    Ishikawa, Masayori; Tanaka, Kenichi; Endo, Satrou; Hoshi, Masaharu

    2015-01-01

    Phantom experiments to evaluate thermal neutron flux distribution were performed using the Scintillator with Optical Fiber (SOF) detector, which was developed as a thermal neutron monitor during boron neutron capture therapy (BNCT) irradiation. Compared with the gold wire activation method and Monte Carlo N-particle (MCNP) calculations, it was confirmed that the SOF detector is capable of measuring thermal neutron flux as low as 105 n/cm2/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources. PMID:25589504

  1. Participation of V. S. Vladimirov in work on the USSR atomic project: A significant milestone in the development of the foundations of mathematical modeling of the processes of neutron physics

    NASA Astrophysics Data System (ADS)

    Trutnev, Yu. A.; Shagaliev, R. M.; Evdokimov, V. V.; Bochkov, A. I.

    2013-02-01

    This paper is dedicated to the 90th anniversary of the birth of a leading Soviet and Russian scientist and a member of the USSR Academy of Sciences: Academician Vasilii Sergeevich Vladimirov. Vladimirov, one of the strongest contemporary mathematicians, worked from 1951 through 1955 at KB-11 (today, the Russian Federal Nuclear Center — All-Russian Scientific Research Institute for Experimental Physics), the "secret facility" where development of atomic weaponry was conducted. We present the main results of Vladimirov's scientific activity connected with his work on the USSR atomic project.

  2. 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.

  3. 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)

  4. Effects of electron correlations application to Ti atoms on physical properties of (LaMnO3)m/(SrTiO3)n superlattices

    NASA Astrophysics Data System (ADS)

    Aezami, A.; Abolhassani, M.; Elahi, M.

    2016-05-01

    Magnetic structures and Curie temperatures of the (LaMnO3)m/(SrTiO3)n superlattices (SLm-n) with m=1, 2, 3 and n=1, 2, 3, 8 were investigated, using density functional theory implemented in Quantum-Espresso open source code. By applying on-site coulomb interaction (Hubbard term U) to Ti atoms for all of these superlattices, using Stoner-Wolfarth model, it was found that the magnetic order of interfacial atoms of these superlattices changed to ferromagnetic by implying U=5 eV on Ti atoms. The inclusion of electron-electron correlation with U=5 eV on the Ti atoms for all of the superlattices made the two dimensional electron gas (2DEG) formed at the interfaces, half-metallic. The obtained values of Curie temperature, calculated within mean field approximation with U=5 eV on the Ti atoms, are in good agreement with the experimental results.

  5. Progress on the accelerator based SPES-BNCT project at INFN Legnaro

    SciTech Connect

    Esposito, J.; Colautti, P.; Pisent, A.; Conte, V.; Moro, D.; De Nardo, L.; Agosteo, S.; Rosi, G.

    2007-02-12

    In the framework of an advanced Exotic Ion Beam facility, named SPES (Study and Production of Exotic Species), that will allow a frontier program both in nuclear and interdisciplinary physics, an intense thermal neutron beam facility, devoted to perform Boron Neutron Capture Therapy (BNCT) experimental treatments on skin melanoma tumor, is currently under construction based on the SPES proton driver. A vast radiobiological investigation in vitro and in vivo has started with the new 10B carriers developed. Special microdosimetric detectors have been constructed to properly measure all the BNCT dose components and their qualities. Both microdosimetric and radiobiological measurements are being performed at the new HYTHOR beam shaping assembly at the Enea-Casaccia TAPIRO reactor.

  6. Recent astrophysical and accelerator-based results on the hadronic equation of state

    NASA Astrophysics Data System (ADS)

    Hartnack, Ch; Oeschler, H.; Aichelin, Jörg

    2006-12-01

    In astrophysics as well as in hadron physics, progress has recently been made on the determination of the hadronic equation of state (EoS) of compressed matter. The results are contradictory, however. Simulations of heavy-ion reactions are now sufficiently robust to predict the stiffness of the EoS from (i) the energy dependence of the ratio of K+ from Au + Au and C + C collisions and (ii) the centrality dependence of the K+ multiplicities. The data are best described with a compressibility coefficient at normal nuclear matter density κ of around 200 MeV, a value which is usually called 'soft'. The recent observation of a neutron star with a mass of twice the solar mass is only compatible with theoretical predictions if the EoS is stiff. We review the present situation.

  7. Generation, transport, and detection of linear accelerator based femtosecond-terahertz pulses.

    PubMed

    Park, Jaehun; Kim, Changbum; Lee, Jongseok; Yim, Changmook; Kim, Chul Hoon; Lee, Junghwa; Jung, Seonghoon; Ryu, Jaehyun; Kang, Heung-Sik; Joo, Taiha

    2011-01-01

    The generation and detection of intense terahertz (THz) radiation has drawn a great attention recently. The dramatically enhanced energy and peak electric field of the coherent THz radiation can be generated by coherent superposition of radiated fields emitted by ultrafast electron bunches. The femtosecond (fs)-THz beamline construction at the Pohang Accelerator Laboratory (PAL) was completed in the end of 2009. The fs-THz beamline at PAL can supply ultrafast and intense fs-THz radiation from a 75 MeV linear accelerator. The radiation is expected to have frequency up to 3 THz (∼100 cm(-1)) and the pulse width of <200 fs with pulse energy up to 10 μJ. This intense THz source has great potential for applications in nonlinear optical phenomena and fields such as material science, biomedical science, chemistry, and physics, etc. PMID:21280823

  8. 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

  9. The relationship between contrast, resolution and detectability in accelerator-based fast neutron radiography

    SciTech Connect

    Ambrosi, R. M.; Watterson, J. I. W.

    1999-06-10

    Fast neutron radiography as a method for non destructive testing is a fast growing field of research. At the Schonland Research Center for Nuclear Sciences we have been engaged in the formulation of a model for the physics of image formation in fast neutron radiography (FNR). This involves examining all the various factors that affect image formation in FNR by experimental and Monte Carlo methods. One of the major problems in the development of a model for fast neutron radiography is the determination of the factors that affect image contrast and resolution. Monte Carlo methods offer an ideal tool for the determination of the origin of many of these factors. In previous work the focus of these methods has been the determination of the scattered neutron field in both a scintillator and a fast neutron radiography facility. As an extension of this work MCNP has been used to evaluate the role neutron scattering in a specimen plays in image detectability. Image processing of fast neutron radiographs is a necessary method of enhancing the detectability of features in an image. MCNP has been used to determine the part it can play in indirectly improving image resolution and aiding in image processing. The role noise plays in fast neutron radiography and its impact on image reconstruction has been evaluated. All these factors aid in the development of a model describing the relationship between contrast, resolution and detectability.

  10. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    NASA Astrophysics Data System (ADS)

    Burlon, Alejandro A.; Girola, Santiago; Valda, Alejandro A.; Minsky, Daniel M.; Kreiner, Andrés J.

    2010-08-01

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  11. Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

    SciTech Connect

    Burlon, Alejandro A.; Valda, Alejandro A.; Girola, Santiago; Minsky, Daniel M.; Kreiner, Andres J.

    2010-08-04

    In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the {sup 7}Li(p, n){sup 7}Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

  12. Accelerator-based analytical technique in the evaluation of some Nigeria’s natural minerals: Fluorite, tourmaline and topaz

    NASA Astrophysics Data System (ADS)

    Olabanji, S. O.; Ige, O. A.; Mazzoli, C.; Ceccato, D.; Akintunde, J. A.; De Poli, M.; Moschini, G.

    2005-10-01

    For the first time, the complementary accelerator-based analytical technique of PIXE and electron microprobe analysis (EMPA) were employed for the characterization of some Nigeria's natural minerals namely fluorite, tourmaline and topaz. These minerals occur in different areas in Nigeria. The minerals are mainly used as gemstones and for other scientific and technological applications and therefore are very important. There is need to characterize them to know the quality of these gemstones and update the geochemical data on them geared towards useful applications. PIXE analysis was carried out using the 1.8 MeV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at INFN, LNL, Legnaro, Padova, Italy. The novel results which show many elements at different concentrations in these minerals are presented and discussed.

  13. Acceleration-based joint stability parameters for total knee arthroplasty that correspond with patient-reported instability.

    PubMed

    Roberts, Dustyn; Khan, Humera; Kim, Joo H; Slover, James; Walker, Peter S

    2013-10-01

    There is no universally accepted definition of human joint stability, particularly in nonperiodic general activities of daily living. Instability has proven to be a difficult parameter to define and quantify, since both spatial and temporal measures need to be considered to fully characterize joint stability. In this preliminary study, acceleration-based parameters were proposed to characterize the joint stability. Several time-statistical parameters of acceleration and jerk were defined as potential stability measures, since anomalous acceleration or jerk could be a symptom of poor control or stability. An inertial measurement unit attached at the level of the tibial tubercle of controls and patients following total knee arthroplasty was used to determine linear acceleration of the knee joint during several activities of daily living. The resulting accelerations and jerks were compared with patient-reported instability as determined through a standard questionnaire. Several parameters based on accelerations and jerks in the anterior/posterior direction during the step-up/step-down activity were significantly different between patients and controls and correlated with patient reports of instability in that activity. The range of the positive to negative peak acceleration and infinity norm of acceleration, in the anterior/posterior direction during the step-up/step-down activity, proved to be the best indicators of instability. As time derivatives of displacement, these acceleration-based parameters represent spatial and temporal information and are an important step forward in developing a definition and objective quantification of human joint stability that can complement the subjective patient report. PMID:23886970

  14. Atomic and molecular supernovae

    SciTech Connect

    Liu, W.

    1997-12-01

    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.

  15. 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.

  16. Physics of leptoquarks in precision experiments and at particle colliders

    NASA Astrophysics Data System (ADS)

    Doršner, I.; Fajfer, S.; Greljo, A.; Kamenik, J. F.; Košnik, N.

    2016-06-01

    We present a comprehensive review of physics effects generated by leptoquarks (LQs), i.e., hypothetical particles that can turn quarks into leptons and vice versa, of either scalar or vector nature. These considerations include discussion of possible completions of the Standard Model that contain LQ fields. The main focus of the review is on those LQ scenarios that are not problematic with regard to proton stability. We accordingly concentrate on the phenomenology of light leptoquarks that is relevant for precision experiments and particle colliders. Important constraints on LQ interactions with matter are derived from precision low-energy observables such as electric dipole moments, (g - 2) of charged leptons, atomic parity violation, neutral meson mixing, Kaon, B, and D meson decays, etc. We provide a general analysis of indirect constraints on the strength of LQ interactions with the quarks and leptons to make statements that are as model independent as possible. We address complementary constraints that originate from electroweak precision measurements, top, and Higgs physics. The Higgs physics analysis we present covers not only the most recent but also expected results from the Large Hadron Collider (LHC). We finally discuss direct LQ searches. Current experimental situation is summarized and self-consistency of assumptions that go into existing accelerator-based searches is discussed. A progress in making next-to-leading order predictions for both pair and single LQ productions at colliders is also outlined.

  17. Role of atomic collisions in fusion

    SciTech Connect

    Post, D.E.

    1982-04-01

    Atomic physics issues have played a large role in controlled fusion research. A general discussion of the present role of atomic processes in both magnetic and inertial controlled fusion work is presented.

  18. 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)…

  19. Bonds Between Atoms.

    ERIC Educational Resources Information Center

    Holden, Alan

    The field of inquiry into how atoms are bonded together to form molecules and solids crosses the borderlines between physics and chemistry encompassing methods characteristic of both sciences. At one extreme, the inquiry is pursued with care and rigor into the simplest cases; at the other extreme, suggestions derived from the more careful inquiry…

  20. 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…

  1. Electron energy and electron trajectories in an inverse free-electron laser accelerator based on a novel electrostatic wiggler

    NASA Astrophysics Data System (ADS)

    Nikrah, M.; Jafari, S.

    2016-06-01

    We expand here a theory of a high-gradient laser-excited electron accelerator based on an inverse free-electron laser (inverse-FEL), but with innovations in the structure and design. The electrostatic wiggler used in our scheme, namely termed the Paul wiggler, is generated by segmented cylindrical electrodes with applied oscillatory voltages {{V}\\text{osc}}(t) over {{90}\\circ} segments. The inverse-FEL interaction can be described by the equations that govern the electron motion in the combined fields of both the laser pulse and Paul wiggler field. A numerical study of electron energy and electron trajectories has been made using the fourth-order Runge–Kutta method. The results indicate that the electron attains a considerable energy at short distances in this device. It is found that if the electron has got sufficient suitable wiggler amplitude intensities, it can not only gain higher energy in longer distances, but also can retain it even after the passing of the laser pulse. In addition, the results reveal that the electron energy gains different peaks for different initial axial velocities, so that a suitable small initial axial velocity of e-beam produces substantially high energy gain. With regard to the transverse confinement of the electron beam in a Paul wiggler, there is no applied axial guide magnetic field in this device.

  2. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT.

    PubMed

    Evans, J F; Blue, T E

    1996-11-01

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions "How much?" and "What kind?" of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room , patient "scatterer," and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h-1 was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. PMID:8887513

  3. Characteristic impedance and capacitance analysis of Blumlein type pulse forming line of accelerator based on tape helix

    SciTech Connect

    Zhang Yu; Liu Jinliang; Fan Xuliang; Zhang Hongbo; Wang Shiwen; Feng Jiahuai

    2011-10-15

    In this paper, the electromagnetic dispersion theory and the classic telegraph equations were combined to calculate the important parameters of the helical Blumlein pulse forming line (BPFL) of accelerator based on tape helix. In the work band of the BPFL at several hundred ns range, electromagnetic dispersion characteristics were almost determined by the zeroth harmonic. In order to testify the dispersion theory of BPFL in this paper, filling dielectrics, such as de-ionized water, transformer oil, and air were employed in the helical BPFL, respectively. Parameters such as capacitance, inductance, characteristic impedance, and pulse duration of the BPFL were calculated. Effects of dispersion on these parameters were analyzed. Circuit simulation and electromagnetic simulation were carried out to prove these parameters of BPFL filled with these three kinds of dielectrics, respectively. The accelerator system was set up, and experimental results also corresponded to the theoretical calculations. The average theoretical errors of impedances and pulse durations were 3.5% and 3.4%, respectively, which proved the electromagnetic dispersion analyses in this paper.

  4. Accelerator-Based Boron Neutron Capture Therapy and the Development of a Dedicated Tandem-Electrostatic-Quadrupole

    SciTech Connect

    Kreiner, A. J.; Di Paolo, H.; Burlon, A. A.; Valda, A. A.; Debray, M. E.; Somacal, H. R.; Minsky, D. M.; Kesque, J. M.; Giboudot, Y.; Levinas, P.; Fraiman, M.; Romeo, V.

    2007-10-26

    There is a generalized perception that the availability of suitable particle accelerators installed in hospitals, as neutron sources, may be crucial for the advancement of Boron Neutron Capture Therapy (BNCT). Progress on an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator for Accelerator-Based (AB)-BNCT is described here. The project goal is a machine capable of delivering 30 mA of 2.5 MeV protons to be used in conjunction with a neutron production target based on the {sup 7}Li(p,n){sup 7}Be reaction slightly beyond its resonance at 2.25 MeV. A folded tandem, with 1.25 MV terminal voltage, combined with an ESQ chain is being designed and constructed. A 30 mA proton beam of 2.5 MeV are the specifications needed to produce sufficiently intense and clean epithermal neutron beams, based on the {sup 7}Li(p,n){sup 7}Be reaction, to perform BNCT treatment for deep-seated tumors in less than an hour. The first design and construction of an ESQ module is discussed and its electrostatic fields are investigated theoretically and experimentally. Also new beam transport calculations through the accelerator are presented.

  5. Shielding design of a treatment room for an accelerator-based epithermal neutron irradiation facility for BNCT

    SciTech Connect

    Evans, J.F.; Blue, T.E.

    1996-11-01

    Protecting the facility personnel and the general public from radiation exposure is a primary safety concern of an accelerator-based epithermal neutron irradiation facility. This work makes an attempt at answering the questions {open_quotes}How much?{close_quotes} and {open_quotes}What kind?{close_quotes} of shielding will meet the occupational limits of such a facility. Shielding effectiveness is compared for ordinary and barytes concretes in combination with and without borated polyethylene. A calculational model was developed of a treatment room, patient {open_quotes}scatterer,{close_quotes} and the epithermal neutron beam. The Monte Carlo code, MCNP, was used to compute the total effective dose equivalent rates at specific points of interest outside of the treatment room. A conservative occupational effective dose rate limit of 0.01 mSv h{sup {minus}1} was the guideline for this study. Conservative Monte Carlo calculations show that constructing the treatment room walls with 1.5 m of ordinary concrete, 1.2 m of barytes concrete, 1.0 m of ordinary concrete preceded by 10 cm of 5% boron-polyethylene, or 0.8 m of barytes concrete preceded by 10 cm of 5% boron-polyethylene will adequately protect facility personnel. 20 refs., 8 figs., 2 tabs.

  6. Accelerator-based analytical technique in the study of some anti-diabetic medicinal plants of Nigeria

    NASA Astrophysics Data System (ADS)

    Olabanji, S. O.; Omobuwajo, O. R.; Ceccato, D.; Adebajo, A. C.; Buoso, M. C.; Moschini, G.

    2008-05-01

    Diabetes mellitus, a clinical syndrome characterized by hyperglycemia due to deficiency of insulin, is a disease involving the endocrine pancreas and causes considerable morbidity and mortality in the world. In Nigeria, many plants, especially those implicated in herbal recipes for the treatment of diabetes, have not been screened for their elemental constituents while information on phytochemistry of some of them is not available. There is therefore the need to document these constituents as some of these plants are becoming increasingly important as herbal drugs or food additives. The accelerator-based technique PIXE, using the 1.8 MeV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at INFN, LNL, Legnaro (Padova) Italy, was employed in the determination of the elemental constituents of these anti-diabetic medicinal plants. Leaves of Gardenia ternifolia, Caesalpina pulcherrima, Solemostenon monostachys, whole plant of Momordica charantia and leaf and stem bark of Hunteria umbellata could be taken as vegetables, neutraceuticals, food additives and supplements in the management of diabetes. However, Hexabolus monopetalus root should be used under prescription.

  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. On the dependence of solar flare X-ray spectral line intensity ratios of highly ionized sulfur, calcium, and iron on electron temperature, differential emission measure, and atomic physics

    NASA Technical Reports Server (NTRS)

    Doschek, G. A.; Fludra, A.; Bentley, R. D.; Lang, J.; Phillips, K. J. H.

    1990-01-01

    This paper focuses on what can be learned about the emission measure distribution and certain atomic physics parameters from spectral lines of highly ionized ions of sulfur, calcium, and iron that appear in solar flare spectra. The particular lines chosen for analysis allow the electron temperature to be determined independently of the assumption of ionization equilibrium. An attempt is made to find emission measure models based on selected functional dependences of emission measure on temperature that reproduce the observed temperatures deduced from spectral line ratios as well as the relative intensities of resonance lines of different elements.

  9. 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.

  10. 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.

  11. Exotic atoms: Antimatter may matter

    NASA Astrophysics Data System (ADS)

    Phillips, Thomas J.

    2016-01-01

    The charge neutrality of the antimatter atom antihydrogen has been confirmed with unprecedented accuracy, paving the way for experiments that could simultaneously solve several of physics' biggest mysteries. See Letter p.373

  12. 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.

  13. 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.

  14. Liquid atomization

    SciTech Connect

    Walzel, P. )

    1993-01-01

    A systematic review of different liquid atomizers is presented, accompanied by a discussion of various mechanisms of droplet formation in a gas atmosphere as a function of the liquid flow-regime and the geometry of the atomizer. Equations are presented for the calculation of the mean droplet-diameter. In many applications, details of the droplet size distribution are, also, important, e.g., approximate values of the breadth of the droplet formation are given. The efficiency of utilization of mechanical energy in droplet formation is indicated for the different types of atomizers. Atomization is used, in particular, for the following purposes: (1) atomization of fuels; (2) making granular products; (3) carrying out mass-transfer operations; and (4) coating of surfaces.

  15. 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,…

  16. 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…

  17. Factors Predictive of Symptomatic Radiation Injury After Linear Accelerator-Based Stereotactic Radiosurgery for Intracerebral Arteriovenous Malformations

    SciTech Connect

    Herbert, Christopher; Moiseenko, Vitali; McKenzie, Michael; Redekop, Gary; Hsu, Fred; Gete, Ermias; Gill, Brad; Lee, Richard; Luchka, Kurt; Haw, Charles; Lee, Andrew; Toyota, Brian; Martin, Montgomery

    2012-07-01

    Purpose: To investigate predictive factors in the development of symptomatic radiation injury after treatment with linear accelerator-based stereotactic radiosurgery for intracerebral arteriovenous malformations and relate the findings to the conclusions drawn by Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC). Methods and Materials: Archived plans for 73 patients who were treated at the British Columbia Cancer Agency were studied. Actuarial estimates of freedom from radiation injury were calculated using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards models were used for analysis of incidence of radiation injury. Log-rank test was used to search for dosimetric parameters associated with freedom from radiation injury. Results: Symptomatic radiation injury was exhibited by 14 of 73 patients (19.2%). Actuarial rate of symptomatic radiation injury was 23.0% at 4 years. Most patients (78.5%) had mild to moderate deficits according to Common Terminology Criteria for Adverse Events, version 4.0. On univariate analysis, lesion volume and diameter, dose to isocenter, and a V{sub x} for doses {>=}8 Gy showed statistical significance. Only lesion diameter showed statistical significance (p < 0.05) in a multivariate model. According to the log-rank test, AVM volumes >5 cm{sup 3} and diameters >30 mm were significantly associated with the risk of radiation injury (p < 0.01). The V{sub 12} also showed strong association with the incidence of radiation injury. Actuarial incidence of radiation injury was 16.8% if V{sub 12} was <28 cm{sup 3} and 53.2% if >28 cm{sup 3} (log-rank test, p = 0.001). Conclusions: This study confirms that the risk of developing symptomatic radiation injury after radiosurgery is related to lesion diameter and volume and irradiated volume. Results suggest a higher tolerance than proposed by QUANTEC. The widely differing findings reported in the literature, however, raise considerable uncertainties.

  18. Composition influence on the physical and electrical properties of SrxTi1-xOy-based metal-insulator-metal capacitors prepared by atomic layer deposition using TiN bottom electrodes

    NASA Astrophysics Data System (ADS)

    Menou, N.; Popovici, M.; Clima, S.; Opsomer, K.; Polspoel, W.; Kaczer, B.; Rampelberg, G.; Tomida, K.; Pawlak, M. A.; Detavernier, C.; Pierreux, D.; Swerts, J.; Maes, J. W.; Manger, D.; Badylevich, M.; Afanasiev, V.; Conard, T.; Favia, P.; Bender, H.; Brijs, B.; Vandervorst, W.; Van Elshocht, S.; Pourtois, G.; Wouters, D. J.; Biesemans, S.; Kittl, J. A.

    2009-11-01

    In this work, the physical and electrical properties of SrxTi1-xOy (STO)-based metal-insulator-metal capacitors (MIMcaps) with various compositions are studied in detail. While most recent studies on STO were done on noblelike metal electrodes (Ru, Pt), this work focuses on a low temperature (250 °C) atomic layer deposition (ALD) process, using an alternative precursor set and carefully optimized processing conditions, enabling the use of low-cost, manufacturable-friendly TiN electrodes. Physical analyses show that the film crystallization temperature, its texture and morphology strongly depends on the Sr/Ti ratio. Such physical variations have a direct impact on the electric properties of SrxTi1-xOy based capacitors. It is found that Sr-enrichment result in a monotonous decrease in the dielectric constant and leakage current as predicted by ab initio calculations. The intercept of the EOT vs physical thickness plot further indicates that increasing the Sr-content at the film interface with the bottom TiN would result in lower interfacial equivalent-oxide thickness.

  19. Simulations of an Accelerator-based Shielding Shielding Experiment Using theParticle and Heavy-Ion Transport code System PHITS

    NASA Astrophysics Data System (ADS)

    Sato, T.; Sihver, L.; Iwase, H.; Nakashima, H.; Niita, K.

    In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS), which is based on the NMTC and MCNP for nucleon/meson and neutron transport respectively, and the JAM hadron cascade model. PHITS uses JAERI Quantum Molecular Dynamics (JQMD) and the GEM (Generalized Evaporation Model) for calculations of fission and evaporation processes, the SHEN model for calculation of total reaction cross sections, and the SPAR model for dE/dx calculations. The development of PHITS includes better parameterization in the JQMD model used for the nucleus-nucleus reactions, improvement of the models used for calculating total reaction cross sections and dE/dx distributions, and adding routines for calculating elastic scattering of heavy ions, dose and track average LET distributions. As part of an extensive bench marking of PHITS, we have compared energy spectra of secondary neutrons created by reactions of HZE particles with different targets, with thicknesses ranging from < 1 cm to 200 cm. We have also compared simulated and measured spatial, fluence and depth-dose distributions from different high energy heavy ion reactions. In this paper we report simulations of an accelerator-based shielding experiment, in which a beam of 1 GeV/n Fe-ions has passed through slabs of polyethylene, PMMA, Al, and Pb, with thicknesses ranging from 5 to 30 g/cm2 at an acceptance angle of 0°± 3°. The simulated survival fraction of the primary Fe-ions, fragment spectrum for 23 g/cm2, and dose behind the shield per incident Fe-ion on the shield has been compared with measurements.

  20. 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.

  1. 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.

  2. 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)

  3. Energy partitioning for ``fuzzy'' atoms

    NASA Astrophysics Data System (ADS)

    Salvador, P.; Mayer, I.

    2004-03-01

    The total energy of a molecule is presented as a sum of one- and two-atomic energy components in terms of "fuzzy" atoms, i.e., such divisions of the three-dimensional physical space into atomic regions in which the regions assigned to the individual atoms have no sharp boundaries but exhibit a continuous transition from one to another. By proper definitions the energy components are on the chemical energy scale. The method is realized by using Becke's integration scheme and weight function permitting very effective numerical integrations.

  4. 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)

  5. 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)

  6. 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.

  7. 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)

  8. Cold Atoms

    NASA Astrophysics Data System (ADS)

    Bellac, Michel Le

    2014-11-01

    This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

  9. Control of atom-atom entanglement by cavity detuning

    NASA Astrophysics Data System (ADS)

    Calderón, O.; Joya, M. R.; Fonseca Romero, K. M.

    2016-02-01

    Using the atomic levels previously employed to demonstrate a two-photon maser, we show that the atom-atom entanglement produced by the successive passage of two three-level Rydberg atoms across a single-mode lossless cavity can be enhanced using the Stark shift. The atoms are assumed to be prepared in their excited states and to interact with the field during the same amount of time. Employing a physically motivated perturbation-theory approach, we obtain an effective two-level Hamiltonian. We show that, within the limits of validity of the approximation, atomic entanglement can be controlled by changing the frequency of the cavity field, and can be enhanced up to a maximum where the squared concurrence attains the value 16/27.

  10. Cold Atom Magnetometers

    NASA Astrophysics Data System (ADS)

    Eto, Yujiro; Sadrove, Mark; Hirano, Takuya

    Detection of weak magnetic fields with high spatial resolution is an important technology for various applications such as biological imaging, detection of MRI signals and fundamental physics. Cold atom magnetometry enables 10-11 T/ Hz sqrt{text{Hz}} sensitivities at the micron scale, that is, at the scale of a typical biological cell size. This magnetometry takes advantage of unique properties of atomic gaseous Bose-Einstein condensates with internal spin degrees of freedom. In this chapter, we first overview various state-of-the-art magnetometers, addressing their sensitivities and spatial resolutions. Then we describe properties of spinor condensates, ultracold atom magnetometers, and the latest research developments achieved in the FIRST project, especially for the detection of alternate current magnetic fields using a spin-echo-based magnetometer. We also discuss future prospects of the magnetometers.

  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. Actuated atomizer

    NASA Technical Reports Server (NTRS)

    Tilton, Charles (Inventor); Weiler, Jeff (Inventor); Palmer, Randall (Inventor); Appel, Philip (Inventor)

    2008-01-01

    An actuated atomizer is adapted for spray cooling or other applications wherein a well-developed, homogeneous and generally conical spray mist is required. The actuated atomizer includes an outer shell formed by an inner ring; an outer ring; an actuator insert and a cap. A nozzle framework is positioned within the actuator insert. A base of the nozzle framework defines swirl inlets, a swirl chamber and a swirl chamber. A nozzle insert defines a center inlet and feed ports. A spool is positioned within the coil housing, and carries the coil windings having a number of turns calculated to result in a magnetic field of sufficient strength to overcome the bias of the spring. A plunger moves in response to the magnetic field of the windings. A stop prevents the pintle from being withdrawn excessively. A pintle, positioned by the plunger, moves between first and second positions. In the first position, the head of the pintle blocks the discharge passage of the nozzle framework, thereby preventing the atomizer from discharging fluid. In the second position, the pintle is withdrawn from the swirl chamber, allowing the atomizer to release atomized fluid. A spring biases the pintle to block the discharge passage. The strength of the spring is overcome, however, by the magnetic field created by the windings positioned on the spool, which withdraws the plunger into the spool and further compresses the spring.

  13. 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.

  14. 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.

  15. Physical interaction and assembly of Bacillus subtilis spore coat proteins CotE and CotZ studied by atomic force microscopy.

    PubMed

    Liu, Huiqing; Qiao, Haiyan; Krajcikova, Daniela; Zhang, Zhe; Wang, Hongda; Barak, Imrich; Tang, Jilin

    2016-08-01

    The spore of Bacillus subtilis, a dormant type of cell, is surrounded by a complex multilayered protein structure known as the coat. It is composed of over 70 proteins and essential for the spore to withstand extreme environmental conditions and allow germination under favorable conditions. However, understanding how the properties of the coat arise from the interactions among all these proteins is an important challenge. Moreover, many specific protein-protein interactions among the coat proteins are crucial for coat assembly. In this study, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) was applied to investigate the interaction as a dynamic process between two morphogenetic coat proteins, CotE and CotZ. The unbinding force and kinetic parameters characterizing the interaction between CotE and CotZ were obtained. It is found that there is a strong affinity between CotE and CotZ. Furthermore, the assembly behaviors of CotE and CotZ, individually or in combination, were studied by AFM at solid-liquid interfaces. Our results revealed that CotE-CotZ assembly is dependent on their molar ratios and the interaction between CotE and CotZ involves in the CotE-CotZ assembly. PMID:27320701

  16. 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

  17. Fate of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) on soil following accelerant-based fire and liquid decontamination.

    PubMed

    Gravett, M R; Hopkins, F B; Self, A J; Webb, A J; Timperley, C M; Riches, J R

    2014-08-01

    In the event of alleged use of organophosphorus nerve agents, all kinds of environmental samples can be received for analysis. These might include decontaminated and charred matter collected from the site of a suspected chemical attack. In other scenarios, such matter might be sampled to confirm the site of a chemical weapon test or clandestine laboratory decontaminated and burned to prevent discovery. To provide an analytical capability for these contingencies, we present a preliminary investigation of the effect of accelerant-based fire and liquid decontamination on soil contaminated with the nerve agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX). The objectives were (a) to determine if VX or its degradation products were detectable in soil after an accelerant-based fire promoted by aviation fuel, including following decontamination with Decontamination Solution 2 (DS2) or aqueous sodium hypochlorite, (b) to develop analytical methods to support forensic analysis of accelerant-soaked, decontaminated and charred soil and (c) to inform the design of future experiments of this type to improve analytical fidelity. Our results show for the first time that modern analytical techniques can be used to identify residual VX and its degradation products in contaminated soil after an accelerant-based fire and after chemical decontamination and then fire. Comparison of the gas chromatography-mass spectrometry (GC-MS) profiles of VX and its impurities/degradation products from contaminated burnt soil, and burnt soil spiked with VX, indicated that the fire resulted in the production of diethyl methylphosphonate and O,S-diethyl methylphosphonothiolate (by an unknown mechanism). Other products identified were indicative of chemical decontamination, and some of these provided evidence of the decontaminant used, for example, ethyl 2-methoxyethyl methylphosphonate and bis(2-methoxyethyl) methylphosphonate following decontamination with DS2. Sample preparation

  18. The rise of Rydberg physics

    NASA Astrophysics Data System (ADS)

    Cooper, Keith

    2016-04-01

    Quantum computers of the future could operate via the energy transitions of excited atoms, or even from pure light, if a rapidly growing area of atomic physics continues to meet with success, writes Keith Cooper.

  19. 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.

  20. Enhanced Cooling of Hydrogen Atoms by Lithium Atoms

    SciTech Connect

    Cote, R.; Jamieson, M. J.; Yan, Z-C.; Geum, N.; Jeung, G.-H.; Dalgarno, A.

    2000-03-27

    We present calculated scattering lengths for collisions between various isotopic forms of lithium and hydrogen atoms interacting via singlet and triplet molecular states of LiH. We demonstrate that one bound triplet level is supported for each isotopomer {sup 7}LiH , {sup 6}LiH , {sup 7}LiD , and {sup 6}LiD . We obtain large calculated triplet scattering lengths that are stable against uncertainties in the potential. We present elastic and momentum transfer cross sections, and the corresponding rate coefficients, for hydrogen atoms colliding with {sup 7}Li atoms. We suggest that enhanced cooling of trapped atomic hydrogen by {sup 7}Li atoms is feasible. (c) 2000 The American Physical Society.

  1. Optical atomic clocks and metrology

    NASA Astrophysics Data System (ADS)

    Ludlow, Andrew

    2014-05-01

    The atomic clock has long demonstrated the capability to measure time or frequency with very high precision. Consequently, these clocks are used extensively in technological applications such as advanced synchronization or communication and navigation networks. Optical atomic clocks are next- generation timekeepers which reference narrowband optical transitions between suitable atomic states. Many optical time/frequency standards utilize state-of-the-art quantum control and precision measurement. Combined with the ultrahigh quality factors of the atomic resonances at their heart, optical atomic clocks have promised new levels of timekeeping precision, orders of magnitude higher than conventional atomic clocks based on microwave transitions. Such measurement capability enables and/or enhances many of the most exciting applications of these clocks, including the study of fundamental laws of physics through the measurement of time evolution. Here, I will highlight optical atomic clocks and their utility, as well as review recent advances in their development and performance. In particular, I will describe in detail the optical lattice clock and the realization of frequency measurement at the level of one part in 1018. To push the performance of these atomic timekeepers to such a level and beyond, several key advances are being explored worldwide. These will be discussed generally, with particular emphasis on our recent efforts at NIST in developing the optical lattice clock based on atomic ytterbium.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Transition from LEDCOP to ATOMIC

    SciTech Connect

    Magee, N. H.; Abdallah, J.; Colgan, J.; Hakel, P.; Kilcrease, D. P.; Mazevet, S.; Sherrill, M. E.; Fontes, C. J.; Zhang, H.

    2004-01-01

    This paper discusses the development of the ATOMIC code, a new low to mid Z opacity code, which will replace the current Los Alamos low Z opacity code LEDCOP. The ATOMIC code is based on the FINE code, long used by the Los Alamos group for spectral comparisons in local thermodynamic equilibrium (LTE) and for non-LTE calculations, both utilizing the extensive databases from the atomic physics suite of codes based on the work of R.D. Cowan. Many of the plasma physics packages in LEDCOP, such as line broadening and free-free absorption, are being transferred to the new ATOMIC code. A new equation of state (EOS) model is being developed to allow higher density calculations than were possible with either the FINE or LEDCOP codes. Extensive modernization for both ATOMIC and the atomic physics code suites, including conversion to Fortran 90 and parallelization, are underway to speed up the calculations and to allow the use of expanded databases for both the LTE opacity tables and the non-LTE calculations. Future plans for the code will be outlined, including considerations for new generation opacity tables.

  7. Experiments in cold atom optics towards precision atom interferometry

    NASA Astrophysics Data System (ADS)

    Aveline, David C.

    magnetic field contours of the traps and the dynamics of atoms within those confining potentials. We also controlled the propagation along the atom chip guides by accelerating atoms with longitudinal magnetic gradients, and investigated an atom focusing scheme. While the atom chip wire guides perform a role analogous to optical fibers guiding light waves, "free space" cold atoms offer great opportunity for precision interferometry. We describe a second on-going atom optics experiment that measures gravity gradients using a pair of atom fountain interferometers separated by one meter. We have demonstrated Gravity Gradiometer resolution down to 4x10-9 g/m using a 40 kg test mass. The atomic physics subsystem is described in detail, including the vacuum, cold atom source, optics, magnetic coils and shields, and vibration isolation and compensation. The system is designed to be a compact, robust, transportable instrument, taking strides towards future gravity gradient measurements in the field. In the realm of space applications, there has been interest for micro-gravity science experiments aboard the International Space Station, along with instrument development for gravity mapping of Earth and planetary bodies with satellite-based instruments. Furthermore, there are ground-based applications for gravity imaging of local density distributions, precision measurement of gravity, as well as proposals for redefining the kilogram, detecting gravitational waves and determining the Gravitational constant.

  8. Rutherford-Bohr atom

    NASA Astrophysics Data System (ADS)

    Heilbron, J. L.

    1981-03-01

    Bohr used to introduce his attempts to explain clearly the principles of the quantum theory of the atom with an historical sketch, beginning invariably with the nuclear model proposed by Rutherford. That was sound pedagogy but bad history. The Rutherford-Bohr atom stands in the middle of a line of work initiated by J.J. Thomson and concluded by the invention of quantum mechanics. Thompson's program derived its inspiration from the peculiar emphasis on models characteristic of British physics of the 19th century. Rutherford's atom was a late product of the goals and conceptions of Victorian science. Bohr's modifications, although ultimately fatal to Thomson's program, initially gave further impetus to it. In the early 1920s the most promising approach to an adequate theory of the atom appeared to be the literal and detailed elaboration of the classical mechanics of multiply periodic orbits. The approach succeeded, demonstrating in an unexpected way the force of an argument often advanced by Thomson: because a mechanical model is richer in implications than the considerations for which it was advanced, it can suggest new directions of research that may lead to important discoveries.

  9. 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.

  10. A Saturnian atom.

    PubMed

    Lee, E; Farrelly, D; Uzer, T

    1997-09-29

    In Bohr's original planetary model of the atom the electron moves along orbits of special geometric simplicity. While wave mechanics precludes the idea that a physical path could be ascribed to the electron, a classical or planetary atom can still be envisaged in which the electronic wavepacket neither spreads nor disperses as its center moves along the Kepler orbit, and this orbit is conned to a single plane in space. We show theoretically how an electronic wavepacket may be localized in this fashion in a similar way to ion confinement in a Penning trap. Because external fields are needed to keep the packet confined, a more fitting analogy than a planetary orbit is the motion of a charged dust grain in one of the rings of a giant planet such as Saturn. PMID:19373405

  11. 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.

  12. Demonstration of a high-intensity neutron source based on a liquid-lithium target for Accelerator based Boron Neutron Capture Therapy.

    PubMed

    Halfon, S; Arenshtam, A; Kijel, D; Paul, M; Weissman, L; Berkovits, D; Eliyahu, I; Feinberg, G; Kreisel, A; Mardor, I; Shimel, G; Shor, A; Silverman, I; Tessler, M

    2015-12-01

    A free surface liquid-lithium jet target is operating routinely at Soreq Applied Research Accelerator Facility (SARAF), bombarded with a ~1.91 MeV, ~1.2 mA continuous-wave narrow proton beam. The experiments demonstrate the liquid lithium target (LiLiT) capability to constitute an intense source of epithermal neutrons, for Accelerator based Boron Neutron Capture Therapy (BNCT). The target dissipates extremely high ion beam power densities (>3 kW/cm(2), >0.5 MW/cm(3)) for long periods of time, while maintaining stable conditions and localized residual activity. LiLiT generates ~3×10(10) n/s, which is more than one order of magnitude larger than conventional (7)Li(p,n)-based near threshold neutron sources. A shield and moderator assembly for BNCT, with LiLiT irradiated with protons at 1.91 MeV, was designed based on Monte Carlo (MCNP) simulations of BNCT-doses produced in a phantom. According to these simulations it was found that a ~15 mA near threshold proton current will apply the therapeutic doses in ~1h treatment duration. According to our present results, such high current beams can be dissipated in a liquid-lithium target, hence the target design is readily applicable for accelerator-based BNCT. PMID:26300076

  13. Relationships in Physical Science.

    ERIC Educational Resources Information Center

    Goodstein, Madeline Prager; Sitzman, Barbara Pressey

    This document presents activities in the physical sciences. Activities are grouped in the following chapters: (1) "Science and Measurement"; (2) "Measurement Units"; (3) "Introduction to Chemistry"; (4) "The Periodic Table"; (5) "What is Inside an Atom?"; (6) "Bonding"; (7) "Formulas and Equations"; (8) "The Bursting Atom"; (9) "Relationships…

  14. Atom-atom interactions in continuous metallic nanofilms

    NASA Astrophysics Data System (ADS)

    Shirinyan, A. S.; Bilogorodskyy, Yu. S.

    2012-09-01

    Physical reasons of the existence of the nanosystem-size dependence of the potential energy of the neighboring atoms are considered, and a thermodynamic validation of this dependence is given. Solid nanofilms of monoatomic metallic systems having an fcc structure are simulated by the molecular-statics method with the Morse and Sutton-Chen potentials.

  15. 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…

  16. Interaction between single neutral atoms and an ultracold atomic gas

    NASA Astrophysics Data System (ADS)

    Bauer, Michael; Kindermann, Farina; Franzreb, Philipp; Gänger, Benjamin; Phieler, Jan; Chakrabarti, Shrabana; Spethmann, Nicolas; Meschede, Dieter; Widera, Artur

    2013-05-01

    Recently hybrid systems immersing single atoms in a many body system have been a subject of intense interest. Here we present an example of controlled doping of an ultracold Rubidium cloud with single neutral Cesium impurity atoms. We observe thermalization of ``hot'' Cs atoms by elastic interaction with an ultracold Rb gas, employing different schemes of measuring the impurities' energy distribution. In addition we present a concept and review the current status of a new setup, which will be capable of breeding an all optical BEC in a few seconds. Our setup will feature mechanisms for independently manipulating and imaging both single atoms and the BEC, thereby providing an unrivaled level of control over impurities in a quantum gas. Possible research directions include the investigation of coherent impurity physics and the creation and characterization of polarons in a BEC. Funded by the ERC, starting grant project QuantumProbe.

  17. Attosecond physics

    NASA Astrophysics Data System (ADS)

    Krausz, Ferenc; Ivanov, Misha

    2009-01-01

    Intense ultrashort light pulses comprising merely a few wave cycles became routinely available by the turn of the millennium. The technologies underlying their production and measurement as well as relevant theoretical modeling have been reviewed in the pages of Reviews of Modern Physics (Brabec and Krausz, 2000). Since then, measurement and control of the subcycle field evolution of few-cycle light have opened the door to a radically new approach to exploring and controlling processes of the microcosm. The hyperfast-varying electric field of visible light permitted manipulation and tracking of the atomic-scale motion of electrons. Striking implications include controlled generation and measurement of single attosecond pulses of extreme ultraviolet light as well as trains of them, and real-time observation of atomic-scale electron dynamics. The tools and techniques for steering and tracing electronic motion in atoms, molecules, and nanostructures are now becoming available, marking the birth of attosecond physics. In this article these advances are reviewed and some of the expected implications are addressed.

  18. 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.

  19. 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

  20. Atomic magnetometer

    DOEpatents

    Schwindt, Peter; Johnson, Cort N.

    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.

  1. Atomic physics with highly charged ions

    NASA Astrophysics Data System (ADS)

    Richard, P.

    1993-10-01

    The past year has been a busy one for all three accelerators: the LINAC, EBIS, and the tandem. The EBIS continues to deliver beams of highly charged ions around the clock for the study of low energy collisions with gases and surfaces. The electron beam energy was upgraded to 10 keV, and intensities of highly charged species such as Xe(44+) were greatly increased. The tandem, the traditional source of highly charged binary encounter electron production at zero degrees were studied for medium Z (Si,Cl,Cu) projectiles. Recoil momentum spectroscopy has been used to separate the contributions to collisional ionization of one-electron ions (C(5+), O(7+), F(8+)) from the nucleus and the electrons of a He target. Marked structure in the binary encounter electron spectra for Cu(sup q+) on H2 targets was measured for moderate velocity projectiles. Electron capture by slow multiply charged (EBIS) projectiles from laser excited targets has been carried out. Cross sections for capture from Na(3s) and Na*(3p) were measured for velocities between 0.1 and 1 au. The extension of these experiments to laser excited Rydberg targets is proceeding. Electron capture cross sections and average Q values for Ar(16+) on He at velocities between 0.23 and 1.67 au were measured. The charge state distribution of the He recoils following large angle scattering of C(4+) and C(6+) ions at 7.5 keV/u has been measured. Cross sections have been measured for up to sextuple capture from C60 (buckminsterfullerene) by highly charged slow projectiles. Coupled channel calculations for double capture from He by slow multicharge ions were carried out.

  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. 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…

  4. 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)

  5. NIST Databases on Atomic Spectra

    NASA Astrophysics Data System (ADS)

    Reader, J.; Wiese, W. L.; Martin, W. C.; Musgrove, A.; Fuhr, J. R.

    2002-11-01

    The NIST atomic and molecular spectroscopic databases now available on the World Wide Web through the NIST Physics Laboratory homepage include Atomic Spectra Database, Ground Levels and Ionization Energies for the Neutral Atoms, Spectrum of Platinum Lamp for Ultraviolet Spectrograph Calibration, Bibliographic Database on Atomic Transition Probabilities, Bibliographic Database on Atomic Spectral Line Broadening, and Electron-Impact Ionization Cross Section Database. The Atomic Spectra Database (ASD) [1] offers evaluated data on energy levels, wavelengths, and transition probabilities for atoms and atomic ions. Data are given for some 950 spectra and 70,000 energy levels. About 91,000 spectral lines are included, with transition probabilities for about half of these. Additional data resulting from our ongoing critical compilations will be included in successive new versions of ASD. We plan to include, for example, our recently published data for some 16,000 transitions covering most ions of the iron-group elements, as well as Cu, Kr, and Mo [2]. Our compilations benefit greatly from experimental and theoretical atomic-data research being carried out in the NIST Atomic Physics Division. A new compilation covering spectra of the rare gases in all stages of ionization, for example, revealed a need for improved data in the infrared. We have thus measured these needed data with our high-resolution Fourier transform spectrometer [3]. An upcoming new database will give wavelengths and intensities for the stronger lines of all neutral and singly-ionized atoms, along with energy levels and transition probabilities for the persistent lines [4]. A critical compilation of the transition probabilities of Ba I and Ba II [5] has been completed and several other compilations of atomic transition probabilities are nearing completion. These include data for all spectra of Na, Mg, Al, and Si [6]. Newly compiled data for selected ions of Ne, Mg, Si and S, will form the basis for a new

  6. 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.

  7. Data Evaluation Acquired Talys 1.0 Code to Produce 111In from Various Accelerator-Based Reactions

    NASA Astrophysics Data System (ADS)

    Alipoor, Zahra; Gholamzadeh, Zohreh; Sadeghi, Mahdi; Seyyedi, Solaleh; Aref, Morteza

    The Indium-111 physical-decay parameters as a β-emitter radionuclide show some potential for radiodiagnostic and radiotherapeutic purposes. Medical investigators have shown that 111In is an important radionuclide for locating and imaging certain tumors, visualization of the lymphatic system and thousands of labeling reactions have been suggested. The TALYS 1.0 code was used here to calculate excitation functions of 112/114-118Sn+p, 110Cd+3He, 109Ag+3He, 111-114Cd+p, 110/111Cd+d, 109Ag+α to produce 111In using low and medium energy accelerators. Calculations were performed up to 200 MeV. Appropriate target thicknesses have been assumed based on energy loss calculations with the SRIM code. Theoretical integral yields for all the latter reactions were calculated. The TALYS 1.0 code predicts that the production of a few curies of 111In is feasible using a target of isotopically highly enriched 112Cd and a proton energy between 12 and 25 MeV with a production rate as 248.97 MBq·μA-1 · h-1. Minimum impurities shall be produced during the proton irradiation of an enriched 111Cd target yielding a production rate for 111In of 67.52 MBq· μA-1 · h-1.

  8. Physics Division annual report - 1998

    SciTech Connect

    1999-09-07

    Summaries are given of progress accomplished for the year in the following areas: (1) Heavy-Ion Nuclear Physics Research; (2) Operation and Development of Atlas; (3) Medium-Energy Nuclear Physics Research; (4) Theoretical Physics Research; and (5) Atomic and Molecular Physics Research.

  9. 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…

  10. 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.

  11. Development of beryllium-based neutron target system with three-layer structure for accelerator-based neutron source for boron neutron capture therapy.

    PubMed

    Kumada, Hiroaki; Kurihara, Toshikazu; Yoshioka, Masakazu; Kobayashi, Hitoshi; Matsumoto, Hiroshi; Sugano, Tomei; Sakurai, Hideyuki; Sakae, Takeji; Matsumura, Akira

    2015-12-01

    The iBNCT project team with University of Tsukuba is developing an accelerator-based neutron source. Regarding neutron target material, our project has applied beryllium. To deal with large heat load and blistering of the target system, we developed a three-layer structure for the target system that includes a blistering mitigation material between the beryllium used as the neutron generator and the copper heat sink. The three materials were bonded through diffusion bonding using a hot isostatic pressing method. Based on several verifications, our project chose palladium as the intermediate layer. A prototype of the neutron target system was produced. We will verify that sufficient neutrons for BNCT treatment are generated by the device in the near future. PMID:26260448

  12. 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.

  13. 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.

  14. Atomic spectrometry update - atomic mass spectrometry.

    SciTech Connect

    Bacon, J.; Crain, J. S.; McMahon, A. W.; Williams, J. G.; Analytical Chemistry Laboratory; The Macaulay Land Use Research Inst.; Manchester Metropolitan Univ.; Imperial Coll.

    1996-10-01

    The MS and XRF updates have been published together since their introduction in 1988. In the last few years, however, the two sections have been prepared independently of each other and it therefore seemed appropriate to publish the two sections separately. With effect from this issue, the MS Update will appear in the October issue of JAAS and the XRF Update in the November issue. The format used for the MS section is broadly similar to that used last year, with some additional sub-headings. This Update is intended to cover all atomic and stable isotopic MS techniques, but not those used in studies of fundamental nuclear physics and exotic nuclei far from stability. Also excluded are those reports in which MS is used as a tool in the study of molecular processes and of gaseous components. the review is based on critical selection of developments in instrumentation and methodology, notable for their innovation, originality or achievement of significant advances, and is not intended to be comprehensive in its coverage. Conference papers are only included if they contain enough information to show they meet these criteria, and our policy in general remains one of waiting for a development to appear in a full paper before inclusion in the review. a similar policy applies to foreign language papers unlikely to reach a wide audience. Routine applications of atomic MS are not included in this Update and the reader is referred to the Updates on Industrial Analysis: Metals, Chemicals and Advanced Materials (96/416), Environmental Analysis (96/1444) and Clinical and Biological Materials, Food and Beverages (96/2479). Also excluded are those applications, even if not routine, which use atomic spectroscopy as a tool for the study of a non-atomic property, for example, the use of stable isotope labeling of carbon or nitrogen in biomolecules in metabolic studies. There have been few general reviews on atomic MS of note in the period covered by this update. That of Colodner et al

  15. "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…

  16. Laser trapping of radioactive atoms

    SciTech Connect

    Freedman, S.J.

    1995-04-01

    The capability of manipulating neutral atoms with the force of resonant scattered laser light is being exploited in several different areas of research. The author discusses applications in particle and nuclear physics by expediting some measurements of the subtle effects of the fundamental weak interaction in atoms and nuclei. It was shown in two recent experiments that it is possible to efficiently cool accelerator produced short-lived isotopes and load them into magneto-optic traps. These demonstrations open up new possibilities for obtaining the required precision in experiments involving rare radioactive isotopes.

  17. Atomic Energy Basics, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  18. Remote Preparation of an Atomic Quantum Memory

    SciTech Connect

    Rosenfeld, Wenjamin; Berner, Stefan; Volz, Juergen; Weber, Markus; Weinfurter, Harald

    2007-02-02

    Storage and distribution of quantum information are key elements of quantum information processing and future quantum communication networks. Here, using atom-photon entanglement as the main physical resource, we experimentally demonstrate the preparation of a distant atomic quantum memory. Applying a quantum teleportation protocol on a locally prepared state of a photonic qubit, we realized this so-called remote state preparation on a single, optically trapped {sup 87}Rb atom. We evaluated the performance of this scheme by the full tomography of the prepared atomic state, reaching an average fidelity of 82%.

  19. Large spin magnetism with cold atoms

    NASA Astrophysics Data System (ADS)

    Laburthe-Tolra, Bruno

    2016-05-01

    The properties of quantum gases made of ultra-cold atoms strongly depend on the interactions between atoms. These interactions lead to condensed-matter-like collective behavior, so that quantum gases appear to be a new platform to study quantum many-body physics. In this seminar, I will focus on the case where the atoms possess an internal (spin) degrees of freedom. The spin of atoms is naturally larger than that of electrons. Therefore, the study of the magnetic properties of ultra-cold gases allows for an exploration of magnetism beyond the typical situation in solid-state physics where magnetism is associated to the s = 1/2 spin of the electron. I will describe three specific cases: spinor Bose-Einstein condensates, where spin-dependent contact interactions introduce new quantum phases and spin dynamics; large spin magnetic atoms where strong dipole-dipole interactions lead to exotic quantum magnetism; large spin Fermi gases.

  20. Cosmology of atomic dark matter

    NASA Astrophysics Data System (ADS)

    Cyr-Racine, Francis-Yan; Sigurdson, Kris

    2013-05-01

    While, to ensure successful cosmology, dark matter (DM) must kinematically decouple from the standard model plasma very early in the history of the Universe, it can remain coupled to a bath of “dark radiation” until a relatively late epoch. One minimal theory that realizes such a scenario is the atomic dark matter model, in which two fermions oppositely charged under a new U(1) dark force are initially coupled to a thermal bath of “dark photons” but eventually recombine into neutral atomlike bound states and begin forming gravitationally bound structures. As dark atoms have (dark) atom-sized geometric cross sections, this model also provides an example of self-interacting DM with a velocity-dependent cross section. Delayed kinetic decoupling in this scenario predicts novel DM properties on small scales but retains the success of cold DM on larger scales. We calculate the atomic physics necessary to capture the thermal history of this dark sector and show significant improvements over the standard atomic hydrogen calculation are needed. We solve the Boltzmann equations that govern the evolution of cosmological fluctuations in this model and find in detail the impact of the atomic DM scenario on the matter power spectrum and the cosmic microwave background (CMB). This scenario imprints a new length scale, the dark-acoustic-oscillation scale, on the matter density field. This dark-acoustic-oscillation scale shapes the small-scale matter power spectrum and determines the minimal DM halo mass at late times, which may be many orders of magnitude larger than in a typical weakly interacting-massive-particle scenario. This model necessarily includes an extra dark radiation component, which may be favored by current CMB experiments, and we quantify CMB signatures that distinguish an atomic DM scenario from a standard ΛCDM model containing extra free-streaming particles. We finally discuss the impacts of atomic DM on galactic dynamics and show that these provide the

  1. Maria Goeppert Mayer: atoms, molecules and nuclear shells

    SciTech Connect

    Johnson, K.E.

    1986-09-01

    The mathematical physicist's early work in atomic and molecular physics, and her unfamiliarity with the ''fashions'' in nuclear physics, gave her the ideal preparation for solving the puzzle of the nuclear ''magic numbers.''

  2. Space physics educational outreach

    NASA Technical Reports Server (NTRS)

    Copeland, Richard A.

    1995-01-01

    The goal of this Space Physics Educational Outreach project was to develop a laboratory experiment and classroom lecture on Earth's aurora for use in lower division college physics courses, with the particular aim of implementing the experiment and lecture at Saint Mary's College of California. The strategy is to teach physics in the context of an interesting natural phenomenon by investigating the physical principles that are important in Earth's aurora, including motion of charged particles in electric and magnetic fields, particle collisions and chemical reactions, and atomic and molecular spectroscopy. As a by-product, the undergraduate students would develop an appreciation for naturally occurring space physics phenomena.

  3. Atomization in Sparkling Fireworks

    NASA Astrophysics Data System (ADS)

    Inoue, Chihiro; Koshi, Mitsuo; Terashima, Hiroshi; Himeno, Takehiro; Watanabe, Toshinori; Sparkling Fireworks Team

    2013-11-01

    The physics behind the beauty of sparkling fireworks has not been clarified yet due to a lack of coherent visualization results. In the present study, atomization process in sparkling fireworks is elucidated by using a high-speed video camera. In the first-half sequence of the fireworks, the fireball repeatedly expands, bursts, and shrinks due to the high pressure gas inside the fireball. In contrast, in the last-half sequence, the bubbly fireball slightly deforms, and small bubbles burst on the fireball. A scenario of droplets generation is as follows: a liquid thread extends from the bottom of the bursting fireball, and fragments into droplets. Thus the droplets originate from inside the fireball rather than from its surface.

  4. Atoms and molecules in astrophysics

    SciTech Connect

    Lepp, S.

    1993-05-01

    In 1987 supernova was observed in the Large Magellanic Cloud. The supernova, the explosion of a massive star following core collapse, releases a expanding cloud of gas called the ejecta. Because this supernova occured so close to our own galaxy it was the first chance to get high resolution spectra from a supernova ejecta. There have been a few molecular species (CO and SiO) and many more atomic species observed in the ejecta of Supernova 1987a. The ejecta represents an evolving laboratory for atomic and molecular physics. This paper will review models of the ejecta of Supernova 1987a and some other astrophysical objects with a particular emphasis on the atomic and molecular processes involved.

  5. Atomism from Newton to Dalton

    NASA Astrophysics Data System (ADS)

    Schofield, Robert E.

    1981-03-01

    Newton's achievements, both in the Principia and the Opticks, were firmly rooted in an atomistic theory of matter, resembling aspects of modern nuclear physics in its emphasis on fundamental particles held in differing arrays by short and long-range forces. Marred by premature sophistication, its parameters of particle size and shape and interparticulate forces could not be quantified. Although it inspired many scientists of the eighteenth century and was further developed into a qualitative theory which intrigued scientists into the twentieth century, Newtonian unitary corpuscular (or atomistic) matter theory was replaced for most investigators by a variety of substances for which the particulate nature was of less concern than the character of their gross behavior. It was on this basis that Dalton developed his new (chemical) atomism, reifying the multiplicity of substances with separate atoms for each, distinguished by operational differences in their chemical atomic weights.

  6. Neuromorphic Atomic Switch Networks

    PubMed Central

    Martin-Olmos, Cristina; Shieh, Hsien Hang; Aono, Masakazu; Stieg, Adam Z.; Gimzewski, James K.

    2012-01-01

    Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system. PMID:22880101

  7. Inductively guided circuits for ultracold dressed atoms.

    PubMed

    Sinuco-León, German A; Burrows, Kathryn A; Arnold, Aidan S; Garraway, Barry M

    2014-01-01

    Recent progress in optics, atomic physics and material science has paved the way to study quantum effects in ultracold atomic alkali gases confined to non-trivial geometries. Multiply connected traps for cold atoms can be prepared by combining inhomogeneous distributions of DC and radio-frequency electromagnetic fields with optical fields that require complex systems for frequency control and stabilization. Here we propose a flexible and robust scheme that creates closed quasi-one-dimensional guides for ultracold atoms through the 'dressing' of hyperfine sublevels of the atomic ground state, where the dressing field is spatially modulated by inductive effects over a micro-engineered conducting loop. Remarkably, for commonly used atomic species (for example, (7)Li and (87)Rb), the guide operation relies entirely on controlling static and low-frequency fields in the regimes of radio-frequency and microwave frequencies. This novel trapping scheme can be implemented with current technology for micro-fabrication and electronic control. PMID:25348163

  8. Committee on Atomic, Molecular and Optical Sciences

    SciTech Connect

    Lancaster, James

    2015-06-30

    The Committee on Atomic, Molecular, and Optical Sciences (CAMOS) is a standing activity of the National Research Council (NRC) that operates under the auspices of the Board on Physics and Astronomy. CAMOS is one of five standing committees of the BPA that are charged with assisting it in achieving its goals—monitoring the health of physics and astronomy, identifying important new developments at the scientific forefronts, fostering interactions with other fields, strengthening connections to technology, facilitating effective service to the nation, and enhancing education in physics. CAMOS provides these capabilities for the atomic, molecular and optical (AMO) sciences.

  9. 'Seeing' atoms: the crystallographic revolution.

    PubMed

    Schwarzenbach, Dieter

    2014-01-01

    Laue's experiment in 1912 of the diffraction of X-rays by crystals led to one of the most influential discoveries in the history of science: the first determinations of crystal structures, NaCl and diamond in particular, by W. L. Bragg in 1913. For the first time, the visualisation of the structure of matter at the atomic level became possible. X-ray diffraction provided a sort of microscope with atomic resolution, atoms became observable physical objects and their relative positions in space could be seen. All branches of science concerned with matter, solid-state physics, chemistry, materials science, mineralogy and biology, could now be firmly anchored on the spatial arrangement of atoms. During the ensuing 100 years, structure determination by diffraction methods has matured into an indispensable method of chemical analysis. We trace the history of the development of 'small-structure' crystallography (excepting macromolecular structures) in Switzerland. Among the pioneers figure Peter Debye and Paul Scherrer with powder diffraction, and Paul Niggli and his Zurich School with space group symmetry and geometrical crystallography. Diffraction methods were applied early on by chemists at the Universities of Bern and Geneva. By the 1970s, X-ray crystallography was firmly established at most Swiss Universities, directed by full professors. Today, chemical analysis by structure determination is the task of service laboratories. However, the demand of diffraction methods to solve problems in all disciplines of science is still increasing and powerful radiation sources and detectors are being developed in Switzerland and worldwide. PMID:24801690

  10. Accelerator based epithermal neutron source

    NASA Astrophysics Data System (ADS)

    Taskaev, S. Yu.

    2015-11-01

    We review the current status of the development of accelerator sources of epithermal neutrons for boron neutron capture therapy (BNCT), a promising method of malignant tumor treatment. Particular attention is given to the source of epithermal neutrons on the basis of a new type of charged particle accelerator: tandem accelerator with vacuum insulation and lithium neutron-producing target. It is also shown that the accelerator with specialized targets makes it possible to generate fast and monoenergetic neutrons, resonance and monoenergetic gamma-rays, alpha-particles, and positrons.

  11. ACCELERATOR BASED CONTINUOUS NEUTRON SOURCE.

    SciTech Connect

    SHAPIRO,S.M.; RUGGIERO,A.G.; LUDEWIG,H.

    2003-03-25

    Until the last decade, most neutron experiments have been performed at steady-state, reactor-based sources. Recently, however, pulsed spallation sources have been shown to be very useful in a wide range of neutron studies. A major review of neutron sources in the US was conducted by a committee chaired by Nobel laureate Prof. W. Kohn: ''Neutron Sources for America's Future-BESAC Panel on Neutron Sources 1/93''. This distinguished panel concluded that steady state and pulsed sources are complementary and that the nation has need for both to maintain a balanced neutron research program. The report recommended that both a new reactor and a spallation source be built. This complementarity is recognized worldwide. The conclusion of this report is that a new continuous neutron source is needed for the second decade of the 20 year plan to replace aging US research reactors and close the US neutron gap. it is based on spallation production of neutrons using a high power continuous superconducting linac to generate protons impinging on a heavy metal target. There do not appear to be any major technical challenges to the building of such a facility since a continuous spallation source has been operating in Switzerland for several years.

  12. Electron acceleration based on a laser pulse propagating through a plasma in the simultaneous presence of a helical wiggler and an obliquely applied external magnetic field

    NASA Astrophysics Data System (ADS)

    Gashti, M. A.; Jafari, S.

    2016-06-01

    Electron acceleration based on a laser pulse propagating through plasma channel has been studied in the simultaneous presence of a helical magnetic wiggler and an obliquely applied external magnetic field. A numerical study of electron energy and electron trajectory has been made using the fourth-order Runge-kutta method. Numerical results indicate that electron energy increases with decreasing θ -angle of the obliquely external magnetic field. Besides, it increases with increasing the amplitude of the obliquely magnetic field. It is also found that the electron attains a higher energy at shorter distances for higher amplitude of the wiggler field Ωw . Therefore, employing a magnetic wiggler field is very beneficial for electron acceleration in short distances. Further new results reveal that in the absence of the wiggler field (Ωw=0) , the electron energy increases with increasing the laser intensity, whereas in the presence of the wiggler field (Ωwneq0) , the electron energy increases with decreasing the laser intensity. As a result, employing a wiggler magnetic field in the laser-based electron accelerators can be worthwhile in the design of table top accelerators and it can enhance the electron energy at lower laser intensities.

  13. Analytical approximations for matter effects on CP violation in the accelerator-based neutrino oscillations with E ≲ 1 GeV

    NASA Astrophysics Data System (ADS)

    Xing, Zhi-zhong; Zhu, Jing-yu

    2016-07-01

    Given an accelerator-based neutrino experiment with the beam energy E ≲ 1 GeV, we expand the probabilities of ν μ → ν e and {overline{ν}}_{μ}to {overline{ν}}_e oscillations in matter in terms of two small quantities Δ21 /Δ31 and A/Δ31, where Δ 21≡ m 2 2 - m 1 2 and Δ 31≡ m 3 2 - m 1 2 are the neutrino mass-squared differences, and A measures the strength of terrestrial matter effects. Our analytical approximations are numerically more accurate than those made by Freund in this energy region, and thus they are particularly applicable for the study of leptonic CP violation in the low-energy MOMENT, ESS νSM and T2K oscillation experiments. As a by-product, the new analytical approximations help us to easily understand why the matter-corrected Jarlskog parameter tilde{J} peaks at the resonance energy E ∗ ≃ 0 .14GeV (or 0 .12 GeV) for the normal (or inverted) neutrino mass hierarchy, and how the three Dirac unitarity triangles are deformed due to the terrestrial matter contamination. We also affirm that a medium-baseline neutrino oscillation experiment with the beam energy E lying in the E ∗ ≲ E ≲ 2 E ∗ range is capable of exploring leptonic CP violation with little matter-induced suppression.

  14. Preliminary energy-filtering neutron imaging with time-of-flight method on PKUNIFTY: A compact accelerator based neutron imaging facility at Peking University

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Zou, Yubin; Wen, Weiwei; Lu, Yuanrong; Guo, Zhiyu

    2016-07-01

    Peking University Neutron Imaging Facility (PKUNIFTY) works on an accelerator-based neutron source with a repetition period of 10 ms and pulse duration of 0.4 ms, which has a rather low Cd ratio. To improve the effective Cd ratio and thus improve the detection capability of the facility, energy-filtering neutron imaging was realized with the intensified CCD camera and time-of-flight (TOF) method. Time structure of the pulsed neutron source was firstly simulated with Geant4, and the simulation result was evaluated with experiment. Both simulation and experiment results indicated that fast neutrons and epithermal neutrons were concentrated in the first 0.8 ms of each pulse period; meanwhile in the period of 0.8-2.0 ms only thermal neutrons existed. Based on this result, neutron images with and without energy filtering were acquired respectively, and it showed that detection capability of PKUNIFTY was improved with setting the exposure interval as 0.8-2.0 ms, especially for materials with strong moderating capability.

  15. Ultracold-Atom Accelerometers

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1995-01-01

    Proposed class of accelerometers and related motion sensors based on use of ultracold atoms as inertial components of motion transducers. Ultracold atoms supplant spring-and-mass components of older accelerometers. As used here, "ultracold atoms" means atoms with kinetic energies equivalent to temperatures equal to or less than 20 mK. Acclerometers essentially frictionless. Primary advantage high sensitivity.

  16. Neutral atom traps.

    SciTech Connect

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  17. Laser Methods in the Study of Nuclei, Atoms and Molecules

    NASA Astrophysics Data System (ADS)

    Inamura, Takashi T.

    2005-01-01

    The VIth International Workshop on Application of Lasers in Atomic Nuclei Research was held at Adam Mickiewicz University, Poznan in Poland from May 24 to 27, 2004. Its title this year was "Laser methods in the study of nuclei, atoms and molecules". Some topics are reviewed from a viewpoint of the atomic physics contribution to nuclear physics and its applications. It is suggested how this meeting should be organized in the future by taking the new geopolitics into account.

  18. Atomic Covalent Functionalization of Graphene

    PubMed Central

    Johns, James E.; Hersam, Mark C.

    2012-01-01

    Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

  19. Atomic covalent functionalization of graphene.

    PubMed

    Johns, James E; Hersam, Mark C

    2013-01-15

    Although graphene's physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp(2) bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene's electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (∼1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Toward this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

  20. Control of atomic spin squeezing via quantum coherence

    NASA Astrophysics Data System (ADS)

    Shao, Xuping; Ling, Yang; Yang, Xihua; Xiao, Min

    2016-06-01

    We propose a scheme to generate and control atomic spin squeezing via atomic coherence induced by the strong coupling and probe fields in the Λ-type electromagnetically-induced-transparency configuration in an atomic ensemble. Manipulation of squeezing of the two components in the plane orthogonal to the mean atomic spin direction and generation of nearly perfect squeezing in either component can be achieved by varying the relative intensities of the coupling and probe fields. This method provides a flexible and convenient way to create and control atomic spin squeezing, which may find potential applications in high-precision atomic-physics measurement, quantum coherent control, and quantum information processing.

  1. A Newtonian Model of the Hydrogen Atom

    NASA Astrophysics Data System (ADS)

    Espinosa, James; Woodyard, James

    2010-03-01

    Classical physics was deemed useless in atomic physics in the early 1900's by the vast majority of the physics community. There were multiple problems that were believed to be insoluble, such as blackbody radiation and the photoelectric and Compton effects. Another outstanding problem had been the explanation of atomic spectra. By the 1920's, a very powerful theory called quantum mechanics was created which explained all atomic experiments. Nevertheless, a few physicists, most notably Albert Einstein, rejected this theory on the grounds that it did not give a complete description of the microscopic world. Another more radical view held by Walter Ritz is that Newtonian physics is applicable to all of atomic physics. Over the last couple of years, we have presented classical explanations of many of the ``insoluble'' problems given by textbooks. We will present a model of the hydrogen atom that stays within the framework of Newton. Using only the assumption that the stable building blocks of matter are the electron, positron, and neutrino, we will deduce the following results from our model: orbital stability, line spectra, and scattering cross sections for electrons and protons. We will also qualitatively demonstrate how to explain the lifetime of excited states.

  2. Resonant quantum transitions in trapped antihydrogen atoms.

    PubMed

    Amole, C; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Capra, A; Cesar, C L; Charlton, M; Deller, A; Donnan, P H; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Isaac, C A; Jonsell, S; Kurchaninov, L; Little, A; Madsen, N; McKenna, J T K; Menary, S; Napoli, S C; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sarid, E; Shields, C R; Silveira, D M; Stracka, S; So, C; Thompson, R I; van der Werf, D P; Wurtele, J S

    2012-03-22

    The hydrogen atom is one of the most important and influential model systems in modern physics. Attempts to understand its spectrum are inextricably linked to the early history and development of quantum mechanics. The hydrogen atom's stature lies in its simplicity and in the accuracy with which its spectrum can be measured and compared to theory. Today its spectrum remains a valuable tool for determining the values of fundamental constants and for challenging the limits of modern physics, including the validity of quantum electrodynamics and--by comparison with measurements on its antimatter counterpart, antihydrogen--the validity of CPT (charge conjugation, parity and time reversal) symmetry. Here we report spectroscopy of a pure antimatter atom, demonstrating resonant quantum transitions in antihydrogen. We have manipulated the internal spin state of antihydrogen atoms so as to induce magnetic resonance transitions between hyperfine levels of the positronic ground state. We used resonant microwave radiation to flip the spin of the positron in antihydrogen atoms that were magnetically trapped in the ALPHA apparatus. The spin flip causes trapped anti-atoms to be ejected from the trap. We look for evidence of resonant interaction by comparing the survival rate of trapped atoms irradiated with microwaves on-resonance to that of atoms subjected to microwaves that are off-resonance. In one variant of the experiment, we detect 23 atoms that survive in 110 trapping attempts with microwaves off-resonance (0.21 per attempt), and only two atoms that survive in 103 attempts with microwaves on-resonance (0.02 per attempt). We also describe the direct detection of the annihilation of antihydrogen atoms ejected by the microwaves. PMID:22398451

  3. Atomic Fuel, Understanding the Atom Series. Revised.

    ERIC Educational Resources Information Center

    Hogerton, John F.

    This publication is part of the "Understanding the Atom" series. Complete sets of the series are available free to teachers, schools, and public librarians who can make them available for reference or use by groups. Among the topics discussed are: What Atomic Fuel Is; The Odyssey of Uranium; Production of Uranium; Fabrication of Reactor Fuel…

  4. Atomic Fisher information versus atomic number

    NASA Astrophysics Data System (ADS)

    Nagy, Á.; Sen, K. D.

    2006-12-01

    It is shown that the Thomas Fermi Fisher information is negative. A slightly more sophisticated model proposed by Gáspár provides a qualitatively correct expression for the Fisher information: Gáspár's Fisher information is proportional to the two-third power of the atomic number. Accurate numerical calculations show an almost linear dependence on the atomic number.

  5. Atomic Particle Detection, Understanding the Atom Series.

    ERIC Educational Resources Information Center

    Hellman, Hal

    This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. The instruments used to detect both particles and electromagnetic radiation that emerge from the nucleus are described. The counters reviewed include ionization chambers,…

  6. Cold atom quantum sensors for space

    NASA Astrophysics Data System (ADS)

    Singh, Yeshpal

    2016-07-01

    Quantum sensors based on cold atoms offer the opportunity to perform highly accurate measurements of physical phenomena related to time, gravity and rotation. The deployment of such technologies in the microgravity environment of space may enable further enhancement of their performance, whilst permitting the detection of these physical phenomena over much larger scales than is possible with a ground-based instrument. In this talk, I will present an overview of the activities of the UK National Quantum Hub in Sensors and Metrology in developing cold atoms technology for space. Our activities are focused in two main areas: optical clocks and atom interferometers. I will also discuss our contributions to recent initiatives including STE-QUEST and AI-GOAT, the ESA/NASA initiative aiming at an atom interferometer gravitational wave detector in space.

  7. Radiation dose measurements and Monte Carlo calculations for neutron and photon reactions in a human head phantom for accelerator-based boron neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Kim, Don-Soo

    Dose measurements and radiation transport calculations were investigated for the interactions within the human brain of fast neutrons, slow neutrons, thermal neutrons, and photons associated with accelerator-based boron neutron capture therapy (ABNCT). To estimate the overall dose to the human brain, it is necessary to distinguish the doses from the different radiation sources. Using organic scintillators, human head phantom and detector assemblies were designed, constructed, and tested to determine the most appropriate dose estimation system to discriminate dose due to the different radiation sources that will ultimately be incorporated into a human head phantom to be used for dose measurements in ABNCT. Monoenergetic and continuous energy neutrons were generated via the 7Li(p,n)7Be reaction in a metallic lithium target near the reaction threshold using the 5.5 MV Van de Graaff accelerator at the University of Massachusetts Lowell. A human head phantom was built to measure and to distinguish the doses which result from proton recoils induced by fast neutrons, alpha particles and recoil lithium nuclei from the 10B(n,alpha)7Li reaction, and photons generated in the 7Li accelerator target as well as those generated inside the head phantom through various nuclear reactions at the same time during neutron irradiation procedures. The phantom consists of two main parts to estimate dose to tumor and dose to healthy tissue as well: a 3.22 cm3 boron loaded plastic scintillator which simulates a boron containing tumor inside the brain and a 2664 cm3 cylindrical liquid scintillator which represents the surrounding healthy tissue in the head. The Monte Carlo code MCNPX(TM) was used for the simulation of radiation transport due to neutrons and photons and extended to investigate the effects of neutrons and other radiation on the brain at various depths.

  8. Comparison of the extent of hippocampal sparing according to the tilt of a patient's head during WBRT using linear accelerator-based IMRT and VMAT.

    PubMed

    Moon, Sun Young; Yoon, Myonggeun; Chung, Mijoo; Chung, Weon Kuu; Kim, Dong Wook

    2016-05-01

    In this paper, we report the results of our investigation into whole brain radiotherapy (WBRT) using linear accelerator-based intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) in lung cancer patients with a high risk of metastasis to the brain. Specifically, we assessed the absorbed dose and the rate of adverse effects for several organs at risk (OAR), including the hippocampus, according to the tilt of a patient's head. We arbitrarily selected five cases where measurements were made with the patients' heads tilted forward and five cases without such tilt. We set the entire brain as the planning target volume (PTV), and the hippocampi, the lenses, the eyes, and the cochleae as the main OAR, and formulated new plans for IMRT (coplanar, non-coplanar) and VMAT (coplanar, non-coplanar). Using the dose-volume histogram (DVH), we calculated and compared the effective uniform dose (EUD), normal tissue complication probability (NTCP) of the OAR and the mean and the maximum doses of hippocampus. As a result, if the patient tilted the head forward when receiving the Linac-based treatment, for the same treatment effect in the PTV, we confirmed that a lower dose entered the OAR, such as the hippocampus, eye, lens, and cochlea. Moreover, the damage to the hippocampus was expected to be the least when receiving coplanar VMAT with the head tilted forward. Accordingly, if patients tilt their heads forward when undergoing Linac-based WBRT, we anticipate that a smaller dose would be transmitted to the OAR, resulting in better quality of life following treatment. PMID:27133139

  9. Long-term follow-up results of linear accelerator-based radiosurgery for vestibular schwannoma using serial three-dimensional spoiled gradient-echo MRI.

    PubMed

    Matsuo, Takayuki; Okunaga, Tomohiro; Kamada, Kensaku; Izumo, Tsuyoshi; Hayashi, Nobuyuki; Nagata, Izumi

    2015-02-01

    We examined the characteristic changes in vestibular schwannoma (VS) volume after treatment with linear accelerator-based radiosurgery (LBRS) and the long-term therapeutic effects, by performing three-dimensional (3D) MRI evaluations of tumor volumes. We included 44 patients in whom tumor volume changes could be observed using 3D-spoiled gradient-echo MRI for at least 5 years. Examinations were performed every 3-4 months for the first 2 years after treatment and every 6-12 months thereafter. Enlargement or shrinkage was determined as a change of at least 20% from the volume at the time of treatment. The median observation period was 13.8 years (range, 5.5-19.5 years). The tumor control rates at 5 and 10 years after treatment and at the final MRI were 90.9%, 90.0%, and 88.6%, respectively. Tumor volume changes were categorized into the following four patterns: enlargement, five patients (11.4%); stable, three patients (6.8%); transient enlargement, 24 patients (54.5%); and direct shrinkage, 12 patients (27.3%). Bimodal peaks were observed in three of the 24 patients with transient enlargement. Tumor volume changes from 5 and 10 years post-LBRS to the final observation point were observed in 27 (64.2%) and 10 patients (33.3%), respectively. The long-term tumor volume changes observed after LBRS suggest that radiation exerts long-term effects on tumors. Furthermore, while transient enlargements in tumor volume were characteristic, true tumor enlargements should be characterized by increased volumes of more than two-fold and continued growth for at least 2 years. PMID:25443082

  10. The New Physics

    NASA Astrophysics Data System (ADS)

    Fraser, Gordon

    2009-08-01

    Introduction Gordon Fraser; Part I. Matter and the Universe: 1. Cosmology Wendy Freedman and Rocky Kolb; 2. Gravity Ronald Adler; 3. Astrophysics Arnon Dar; 4. Particles and the standard model Chris Quigg; 5. Superstrings Michael Green; Part II. Quantum Matter: 6. Atoms and photons Claude Cohen-Tannoudji and Jean Dalibard; 7. The quantum world of ultra-cold atoms Christopher Foot and William Phillips; 8. Superfluidity Henry Hall; 9. Quantum phase transitions Subir Sachdev; Part III. Quanta in Action: 10. Quantum entanglement Anton Zeilinger; 11. Quanta, ciphers and computers Artur Ekert; 12. Small-scale structure and nanoscience Yoseph Imry; Part IV. Calculation and Computation: 13. Nonlinearity Henry Abarbanel; 14. Complexity Antonio Politi; 15. Collaborative physics, e-science and the grid Tony Hey and Anne Trefethen; Part V. Science in Action: 16. Biophysics Cyrus Safinya; 17. Medical physics Nicolaj Pavel; 18. Physics and materials Robert Cahn; 19. Physics and society Ugo Amaldi.

  11. The New Physics

    NASA Astrophysics Data System (ADS)

    Fraser, Gordon

    2006-04-01

    Introduction Gordon Fraser; Part I. Matter and the Universe: 1. Cosmology Wendy Freedman and Rocky Kolb; 2. Gravity Ronald Adler; 3. Astrophysics Arnon Dar; 4. Particles and the standard model Chris Quigg; 5. Superstrings Michael Green; Part II. Quantum Matter: 6. Atoms and photons Claude Cohen-Tannoudji and Jean Dalibard; 7. The quantum world of ultra-cold atoms Christopher Foot and William Phillips; 8. Superfluidity Henry Hall; 9. Quantum phase transitions Subir Sachdev; Part III. Quanta in Action: 10. Quantum entanglement Anton Zeilinger; 11. Quanta, ciphers and computers Artur Ekert; 12. Small-scale structure and nanoscience Yoseph Imry; Part IV. Calculation and Computation: 13. Nonlinearity Henry Abarbanel; 14. Complexity Antonio Politi; 15. Collaborative physics, e-science and the grid Tony Hey and Anne Trefethen; Part V. Science in Action: 16. Biophysics Cyrus Safinya; 17. Medical physics Nicolaj Pavel; 18. Physics and materials Robert Cahn; 19. Physics and society Ugo Amaldi.

  12. Atomic scale electron vortices for nanoresearch

    SciTech Connect

    Verbeeck, J.; Van Tendeloo, G.; Schattschneider, P.; Loeffler, S.; Lazar, S.; Stoeger-Pollach, M.; Steiger-Thirsfeld, A.

    2011-11-14

    Electron vortex beams were only recently discovered and their potential as a probe for magnetism in materials was shown. Here we demonstrate a method to produce electron vortex beams with a diameter of less than 1.2 Angst . This unique way to prepare free electrons to a state resembling atomic orbitals is fascinating from a fundamental physics point of view and opens the road for magnetic mapping with atomic resolution in an electron microscope.

  13. In Situ Imaging of Atomic Quantum Gases

    NASA Astrophysics Data System (ADS)

    Hung, Chen-Lung; Chin, Cheng

    2015-09-01

    One exciting progress in recent cold atom experiments is the development of high resolution, in situ imaging techniques for atomic quantum gases.1-3 These new powerful tools provide detailed information on the distribution of atoms in a trap with resolution approaching the level of single atom and even single lattice site, and complement the welldeveloped time-of-flight method that probes the system in momentum space. In a condensed matter analogy, this technique is equivalent to locating electrons of a material in a snap shot. In situ imaging has offered a new powerful tool to study atomic gases and inspired many new research directions and ideas. In this chapter, we will describe the experimental setup of in situ absorption imaging, observables that can be extracted from the images, and new physics that can be explored with this technique.

  14. Friction and Wear on the Atomic Scale

    NASA Astrophysics Data System (ADS)

    Gnecco, Enrico; Bennewitz, Roland; Pfeiffer, Oliver; Socoliuc, Anisoara; Meyer, Ernst

    Friction is an old subject of research: the empirical da Vinci-Amontons laws are common knowledge. Macroscopic experiments systematically performed by the school of Bowden and Tabor have revealed that macroscopic friction can be related to the collective action of small asperities. During the last 15 years, experiments performed with the atomic force microscope gave new insight into the physics of single asperities sliding over surfaces. This development, together with complementary experiments by means of surface force apparatus and quartz microbalance, established the new field of nanotribology. At the same time, increasing computing power allowed for the simulation of the processes in sliding contacts consisting of several hundred atoms. It became clear that atomic processes cannot be neglected in the interpretation of nanotribology experiments. Experiments on even well-defined surfaces directly revealed atomic structures in friction forces. This chapter will describe friction force microscopy experiments that reveal, more or less directly, atomic processes in the sliding contact.

  15. Reviews Equipment: LabQuest 2 Equipment: Rubens' Tube Equipment: Ripple Strobe Tank Book: God and the Atom Book: Magnificent Principia, Exploring Isaac Newton's Masterpiece Book: Talking Science: Language, Learning, and Values Classroom Video: Maxwell's Equations Book: Exploring Quantum Physics Through Hands-on Projects Web Watch

    NASA Astrophysics Data System (ADS)

    2013-11-01

    WE RECOMMEND LabQuest 2 New logger now includes mobile data sharing Rubens' Tube Sturdy Rubens' tube ramps up the beat Ripple Strobe Tank Portable ripple tank makes waves in and out of the lab God and the Atom Expertly told story of the influence of atomism Maxwell's Equations Video stands the test of time Exploring Quantum Physics Through Hands-on Projects Mixture of theory and experiment hits the spot WORTH A LOOK Magnificent Principia, Exploring Isaac Newton's Masterpiece The tricky task of summarizing Newton's iconic work Talking Science: Language, Learning, and Values Interesting book tackles communication in the classroom WEB WATCH Interactive website plans a trip to Mars ... documentary peers into telescopes ... films consider the density of water

  16. Schwinger pair production with ultracold atoms

    NASA Astrophysics Data System (ADS)

    Kasper, V.; Hebenstreit, F.; Oberthaler, M. K.; Berges, J.

    2016-09-01

    We consider a system of ultracold atoms in an optical lattice as a quantum simulator for electron-positron pair production in quantum electrodynamics (QED). For a setup in one spatial dimension, we investigate the nonequilibrium phenomenon of pair production including the backreaction leading to plasma oscillations. Unlike previous investigations on quantum link models, we focus on the infinite-dimensional Hilbert space of QED and show that it may be well approximated by experiments employing Bose-Einstein condensates interacting with fermionic atoms. Numerical calculations based on functional integral techniques give a unique access to the physical parameters required to realize QED phenomena in a cold atom experiment. In particular, we use our approach to consider quantum link models in a yet unexplored parameter regime and give bounds for their ability to capture essential features of the physics. The results suggest a paradigmatic change towards realizations using coherent many-body states for quantum simulations of high-energy particle physics phenomena.

  17. Atomic Spectra Bibliography Databases at NIST

    NASA Astrophysics Data System (ADS)

    Kramida, A. E.

    2007-06-01

    In June 2006, our Atomic Spectroscopy Data Center released three new Bibliographic Databases (BD) containing references to papers with atomic data for controlled fusion research, modeling and diagnostics of astrophysical and terrestrial plasmas, and fundamental properties of electronic spectra of atoms and ions. The NIST Atomic Energy Levels and Spectra BD (http://physics.nist.gov/elevbib) [EL] is the first online version of the NIST bibliography on atomic energy levels and spectra, last published on paper in 1985. It includes more than 9300 references, mostly for years 1967 through 2004. Work is in progress to cover the latest years. The NIST Atomic Transition Probability BD, v. 8.1 (http://physics.nist.gov/fvalbib) [TP] with its 7200 references mainly covers years 1964 through 2006. The NIST Spectral Line Broadening BD, v. 2.0 (http://physics.nist.gov/linebrbib) [LB] has 3600 references, mostly for 1978 through 2006. It is a major upgrade of v. 1.0, which had only 800 references. All three databases are now maintained in a unified database management system that allows us to quickly update the contents. Updates become available to users on the next day. A new Data Entry module makes it easy to enter and categorize the data. This work is supported in part by the Office of Fusion Energy Sciences of the U.S. Department of Energy

  18. BOOK REVIEW: Computational Atomic Structure

    NASA Astrophysics Data System (ADS)

    Post, Douglass E.

    1998-02-01

    The primary purpose of `Computational Atomic Structure' is to give a potential user of the Multi-Configuration Hartree-Fock (MCHF) Atomic Structure Package an outline of the physics and computational methods in the package, guidance on how to use the package, and information on how to interpret and use the computational results. The book is successful in all three aspects. In addition, the book provides a good overview and review of the physics of atomic structure that would be useful to the plasma physicist interested in refreshing his knowledge of atomic structure and quantum mechanics. While most of the subjects are covered in greater detail in other sources, the book is reasonably self-contained, and, in most cases, the reader can understand the basic material without recourse to other sources. The MCHF package is the standard package for computing atomic structure and wavefunctions for single or multielectron ions and atoms. It is available from a number of ftp sites. When the code was originally written in FORTRAN 77, it could only be run on large mainframes. With the advances in computer technology, the suite of codes can now be compiled and run on present day workstations and personal computers and is thus available for use by any physicist, even those with extremely modest computing resources. Sample calculations in interactive mode are included in the book to illustrate the input needed for the code, what types of results and information the code can produce, and whether the user has installed the code correctly. The user can also specify the calculational level, from simple Hartree-Fock to multiconfiguration Hartree-Fock. The MCHF method begins by finding approximate wavefunctions for the bound states of an atomic system. This involves minimizing the energy of the bound state using a variational technique. Once the wavefunctions have been determined, other atomic properties, such as the transition rates, can be determined. The book begins with an

  19. Vortices and turbulence in trapped atomic condensates

    PubMed Central

    White, Angela C.; Anderson, Brian P.; Bagnato, Vanderlei S.

    2014-01-01

    After more than a decade of experiments generating and studying the physics of quantized vortices in atomic gas Bose–Einstein condensates, research is beginning to focus on the roles of vortices in quantum turbulence, as well as other measures of quantum turbulence in atomic condensates. Such research directions have the potential to uncover new insights into quantum turbulence, vortices, and superfluidity and also explore the similarities and differences between quantum and classical turbulence in entirely new settings. Here we present a critical assessment of theoretical and experimental studies in this emerging field of quantum turbulence in atomic condensates. PMID:24704880

  20. The Future of Atom Probe Tomography

    SciTech Connect

    Miller, Michael K; Kelly, T. F.; Rajan, Krishna; Ringer, S. P.

    2012-01-01

    The dream of the microscopy and materials science communities is to see, identify, accurately locate, and determine the fundamental physical properties of every atom in a specimen. With this knowledge together with modern computer models and simulations, a full understanding of the properties of a material can be determined. This fundamental knowledge leads to the design and development of more advanced materials for solving the needs of society. The technique of atom probe tomography is the closest to fulfilling this dream but is still significantly short of the goal. The future of atomic probe tomography, and the prospects for achieving this ultimate goal are outlined.

  1. Rotation Sensing with an Atom Interferometer

    SciTech Connect

    Lenef, A.; Hammond, T.D.; Smith, E.T.; Chapman, M.S.; Rubenstein, R.A.; Pritchard, D.E.

    1997-02-01

    We have measured the phase shift induced by rotation of an atom interferometer at rates of -2 to +2 earth rates and obtained 1{percent} agreement with the predicted Sagnac phase shift for atomic matter waves. The rotational rms noise of our interferometer was 42 milliearth rates for 1 sec of integration time, within 9{percent} of shot noise. The high sensitivity and agreement of predicted and measured behavior suggest useful future scientific applications of atom interferometers as inertial sensors. {copyright} {ital 1997} {ital The American Physical Society}

  2. Atomic dynamics and interatomic interaction in quasicrystals

    SciTech Connect

    Parshin, P. P.; Zemlyanov, M. G.; Brand, R. A.

    2011-12-15

    The previous experimental data on the partial spectra of thermal atomic vibrations in icosahedral (Al{sub 62}Cu{sub 25.5}Fe{sub 12.5}) and decagonal (Al{sub 71.3}Ni{sub 24}Fe{sub 4.7}) quasicrystals have been used to perform a comparative analysis of the atomic dynamics features and determine the role that Al, Cu, Ni, and Fe atoms play in the formation of interatomic interaction in the alloys studied. A physical model of the decagonal quasicrystal structure is proposed.

  3. Calculation of Atomic Data for NASA Missions

    NASA Technical Reports Server (NTRS)

    Gorczyca, T. W.; Korista, K. T.; Fu, J.; Nikolic, D.; Hasoglu, M. F.; Dumitriu, I.; Badnell, N. R.; Savin, D. W.; Manson, S. T.

    2006-01-01

    The interpretation of cosmic spectra relies on a vast sea of atomic data which are not readily obtainable from analytic expressions or simple calculations. Rather, their evaluation typically requires state-of-the-art atomic physics calculations, with the inclusion of weaker effects (spin-orbit and configuration interactions, relaxation, Auger broadening, etc.), to achieve the level of accuracy needed for use by astrophysicists. Our NASA-supported research program is focused on calculating data for three important atomic processes, 1) dielectronic recombination (DR), 2) inner-shell photoabsorption, and 3) fluorescence and Auger decay of inner-shell vacancy states. Some additional details and examples of our recent findings are given.

  4. Seeing Spin Dynamics in Atomic Gases

    NASA Astrophysics Data System (ADS)

    Stamper-Kurn, Dan M.

    2015-06-01

    The dynamics of internal spin, electronic orbital, and nuclear motion states of atoms and molecules have preoccupied the atomic and molecular physics community for decades. Increasingly, such dynamics are being examined within many-body systems composed of atomic and molecular gases. Our findings sometimes bear close relation to phenomena observed in condensed-matter systems, while on other occasions they represent truly new areas of investigation. I discuss several examples of spin dynamics that occur within spinor Bose-Einstein gases, highlighting the advantages of spin-sensitive imaging for understanding and utilizing such dynamics.

  5. Presenting the Bohr Atom.

    ERIC Educational Resources Information Center

    Haendler, Blanca L.

    1982-01-01

    Discusses the importance of teaching the Bohr atom at both freshman and advanced levels. Focuses on the development of Bohr's ideas, derivation of the energies of the stationary states, and the Bohr atom in the chemistry curriculum. (SK)

  6. The atomic strain tensor

    SciTech Connect

    Mott, P.H.; Argon, A.S. ); Suter, U.W. Massachusetts Institute of Technology, Cambridge, MA )

    1992-07-01

    A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated in to Delaunay tetrahedra, identifying interstices, and Voronoi polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronoi polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronoi polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level. 6 refs. 10 figs.

  7. A subfemtotesla multichannel atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Kominis, I. K.; Kornack, T. W.; Allred, J. C.; Romalis, M. V.

    2003-04-01

    The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4K have been unchallenged as ultrahigh-sensitivity magnetic field detectors, with a sensitivity reaching down to 1fTHz-1/2 (1fT = 10-15T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes, but have much lower sensitivity in the more compact designs required for magnetic imaging applications. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54fTHz-1/2 with a measurement volume of only 0.3cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01fTHz-1/2. We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2mm.

  8. A subfemtotesla multichannel atomic magnetometer.

    PubMed

    Kominis, I K; Kornack, T W; Allred, J C; Romalis, M V

    2003-04-10

    The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors, with a sensitivity reaching down to 1 fT Hz(-1/2) (1 fT = 10(-15) T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes, but have much lower sensitivity in the more compact designs required for magnetic imaging applications. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz(-1/2) with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz(-1/2). We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm. PMID:12686995

  9. Atom Wavelike Nature Solved Mathematically

    NASA Astrophysics Data System (ADS)

    Sven, Charles

    2010-02-01

    Like N/S poles of a magnet the strong force field surrounding, confining the nucleus exerts an equal force [noted by this author] driving electrons away from the attraction of positively charged protons force fields in nucleus -- the mechanics for wavelike nature of electron. Powerful forces corral closely packed protons within atomic nucleus with a force that is at least a million times stronger than proton's electrical attraction that binds electrons. This then accounts for the ease of electron manipulation in that electron is already pushed away by the very strong atomic N/S force field; allowing electrons to drive photons when I strike a match. Ageless atom's electron requirements, used to drive light/photons or atom bomb, without batteries, must be supplied from a huge, external, super high frequency, super-cooled source, undetected by current technology, one that could exist 14+ billion years without degradation -- filling a limitless space prior to Big Bang. Using only replicable physics, I show how our Universe emanated from that event. )

  10. Atom Wavelike Nature Solved Mathematically

    NASA Astrophysics Data System (ADS)

    Sven, Charles

    2010-03-01

    Like N/S poles of a magnet the strong force field surrounding, confining the nucleus exerts an equal force [noted by this author] driving electrons away from the attraction of positively charged protons force fields in nucleus -- the mechanics for wavelike nature of electron. Powerful forces corral closely packed protons within atomic nucleus with a force that is at least a million times stronger than proton's electrical attraction that binds electrons. This then accounts for the ease of electron manipulation in that electron is already pushed away by the very strong atomic N/S force field; allowing electrons to drive photons when I strike a match. Ageless atom's electron requirements, used to drive light/photons or atom bomb, without batteries, must be supplied from a huge, external, super high frequency, super-cooled source, undetected by current technology, one that could exist 14+ billion years without degradation -- filling a limitless space prior to Big Bang. Using only replicable physics, I show how our Universe emanated from that event.

  11. Atom Wavelike Nature Solved Mathematically

    NASA Astrophysics Data System (ADS)

    Sven, Charles

    2009-11-01

    Like N/S poles of a magnet the strong force field surrounding, confining the nucleus exerts an equal force [noted by this author] driving electrons away from the attraction of positively charged protons force fields in nucleus -- the mechanics for wavelike nature of electron. Powerful forces corral closely packed protons within atomic nucleus with a force that is at least a million times stronger than proton's electrical attraction that binds electrons. This then accounts for the ease of electron manipulation in that electron is already pushed away by the very strong atomic N/S force field; allowing electrons to drive photons when I strike a match. Ageless atom's electron requirements, used to drive light/photons or atom bomb, without batteries, must be supplied from a huge, external, super high frequency, super-cooled source, undetected by current technology, one that could exist 14+ billion years without degradation -- filling a limitless space prior to Big Bang. Using only replicable physics, I show how our Universe emanated from that event.

  12. Spatially resolved excitation of Rydberg atoms and surface effects on an atom chip

    SciTech Connect

    Tauschinsky, Atreju; Thijssen, Rutger M. T.; Whitlock, S.; Linden van den Heuvell, H. B. van; Spreeuw, R. J. C.

    2010-06-15

    We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold-coated chip surface. We measure distance-dependent shifts ({approx}10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. The measured field strength and distance dependence is in agreement with a simple model for the electric field produced by a localized patch of Rb adsorbates deposited on the chip surface during experiments. The EIT resonances remain narrow (<4 MHz) and the observed widths are independent of atom-surface distance down to {approx} 20 {mu}m, indicating relatively long lifetime of the Rydberg states. Our results open the way to studies of dipolar physics, collective excitations, quantum metrology, and quantum information processing involving interacting Rydberg excited atoms on atom chips.

  13. Atoms in Action

    SciTech Connect

    2009-01-01

    This movie produced with Berkeley Lab's TEAM 0.5 microscope shows the growth of a hole and the atomic edge reconstruction in a graphene sheet. An electron beam focused to a spot on the sheet blows out the exposed carbon atoms to make the hole. The carbon atoms then reposition themselves to find a stable configuration. http://newscenter.lbl.gov/press-releases/2009/03/26/atoms-in-action/

  14. Atomizing nozzle and process

    DOEpatents

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1993-07-20

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  15. Atomizing nozzle and process

    DOEpatents

    Anderson, Iver E.; Figliola, Richard S.; Molnar, Holly M.

    1992-06-30

    High pressure atomizing nozzle includes a high pressure gas manifold having a divergent expansion chamber between a gas inlet and arcuate manifold segment to minimize standing shock wave patterns in the manifold and thereby improve filling of the manifold with high pressure gas for improved melt atomization. The atomizing nozzle is especially useful in atomizing rare earth-transition metal alloys to form fine powder particles wherein a majority of the powder particles exhibit particle sizes having near-optimum magnetic properties.

  16. Adaptive atom-optics in atom interferometry

    NASA Astrophysics Data System (ADS)

    Marable, M. L.; Savard, T. A.; Thomas, J. E.

    1997-02-01

    We suggest a general technique for creating virtual atom-optical elements which are adaptive. The shape and position of these elements is determined by the frequency distribution for optical fields which induce transitions in a high gradient potential. This adaptive method is demonstrated in an all-optical atom interferometer, by creating either a variable optical slit or a variable optical grating which is scanned across the atomic spatial patterns to measure the fringes. This method renders mechanical motion of the interferometer elements unnecessary.

  17. Atomic Spectra Database (ASD)

    National Institute of Standards and Technology Data Gateway

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  18. Advances in antihydrogen physics.

    PubMed

    Charlton, Mike; Van der Werf, Dirk Peter

    2015-01-01

    The creation of cold antihydrogen atoms by the controlled combination of positrons and antiprotons has opened up a new window on fundamental physics. More recently, techniques have been developed that allow some antihydrogen atoms to be created at low enough kinetic energies that they can be held inside magnetic minimum neutral atom traps. With confinement times of many minutes possible, it has become feasible to perform experiments to probe the properties of the antiatom for the first time. We review the experimental progress in this area, outline some of the motivation for studying basic aspects of antimatter physics and provide an outlook of where we might expect this field to go in the coming years. PMID:25942774

  19. Laser spectroscopy of sputtered atoms

    SciTech Connect

    Gruen, D.M.; Pellin, M.J.; Young, C.E.; Calaway, W.F.

    1985-01-01

    The use of laser radiation to study the sputtering process is of relatively recent origin. Much has been learned from this work about the basic physics of the sputtering process itself through measurements of velocity and excited state distributions of sputtered atoms and the effects of adsorbates on substrate sputtering yields. Furthermore, the identification, characterization, and sensitive detection of sputtered atoms by laser spectroscopy has led to the development of in situ diagnostics for impurity fluxes in the plasma edge regions of tokamaks and of ultrasensitive methods (ppB Fe in Si) for surface analysis with ultralow (picocoulomb) ion fluences. The techniques involved in this work, laser fluorescence and multiphoton resonance ionization spectroscopy, will be described and illustrations given of results achieved up to now. 55 refs., 5 figs., 1 tab.

  20. Using atom optics to build nanostructures

    NASA Astrophysics Data System (ADS)

    McClelland, J. J.

    1998-05-01

    Atom optics involves focusing, diffracting, or reflecting atoms, in analogy with what is done to light in conventional optics. Recently, atom optical techniques have been used to control atoms as they land on a substrate. This has led to a new approach to making nanostructures with feature resolution that is in principle only limited by the De Broglie wavelength of the atoms, or the atomic size itself. Recent demonstrations of nanofabrication with atom optics have used the light forces in the nodes of a near-resonant optical standing wave to make large arrays of nanoscale features with high spatial coherence. Directly deposited nanostructures of sodium,(G. Timp, R. E. Behringer, D. M. Tennant, J. E. Cunningham, M. Prentiss, and K. K. Berggren, Phys. Rev. Lett. 69), 1636 (1992). chromium,(J. J. McClelland, R. E. Scholten, E. C. Palm, and R. J. Celotta, Science 262), 877 (1993). and aluminum(R. W. McGowan, D. M. Giltner, and S. A. Lee, Opt. Lett. 20), 877 (1995). have been made with this geometry. Also, patterns have been formed by exposing resists to metastable rare gas atoms(K. K. Berggren, A. Bard, J. L. Wilbur, J. D. Gillaspy, A. G. Helg, J. J. McClelland, S. L. Rolston, W. D. Phillips. M. Prentiss, and G. M. Whitesides, Science 269), 1255 (1995). or alkali atoms.(M. Kreis, F. Lison, D. Haubrich, D. Meschede, S. Nowak, T. Pfau, and J. Mlynek, Appl. Phys. B 63), 649 (1996). Present research is concentrated on examining new ways to utilize atom optics for nanostructure fabrication, and also exploring the practical limits of the process. Two important practical considerations are growth dynamics on the surface, and atomic source quality, that is, brightness, spatial coherence and velocity distribution. Future work will involve cross-disciplinary research with surface physics, and also implementation of a wider range of atom-optical tools, including atom traps, atom holograms, or possibly even Bose-Einstein condensates. This research holds promise for development of

  1. Transport of muonic atoms

    SciTech Connect

    Rusjan, E.

    1988-01-01

    Transport of muonic hydrogen and deuterium atoms in gaseous hydrogen and deuterium is studied in the diffusion approximation and by means of the multiple collision expansion. The diffusion coefficient is derived. Scattering kernels are computed from the kinematics of an inelastic binary collision. The effect of rotations of the target molecules is treated by defining and computing an effective inelastic energy transfer Q{sub eff}. The Doppler effect is taken into account by averaging the cross sections over the Maxwellian velocity distribution of the target molecules. Numerical results of the time-dependent problem in slab geometry are presented. In part two the author constructs a candidate for a realistic four generation Calabi-Yau manifold by dividing an algebraic variety in CP{sub 4} {times} CP{sub 4} with the Z{sub 2} {times} Z{sub 2} symmetry. A nontrivial embedding of Z{sub 2} {times} Z{sub 2} in E(6) allows the physically interesting intermediate symmetry; based on Pati-Salam SU(2){sub L} {times} SU(2){sub R} {times} SU(4){sub C} group. The group of honest symmetries G{sub H} of the manifold is identified and the transformation properties of quark and lepton fields under G{sub H} are given.

  2. Atomic layer epitaxy

    NASA Astrophysics Data System (ADS)

    Goodman, Colin H. L.; Pessa, Markus V.

    1986-08-01

    Atomic layer epitaxy (ALE) is not so much a new technique for the preparation of thin films as a novel modification to existing methods of vapor-phase epitaxy, whether physical [e.g., evaporation, at one limit molecular-beam epitaxy (MBE)] or chemical [e.g., chloride epitaxy or metalorganic chemical vapor deposition (MOCVD)]. It is a self-regulatory process which, in its simplest form, produces one complete molecular layer of a compound per operational cycle, with a greater thickness being obtained by repeated cycling. There is no growth rate in ALE as in other crystal growth processes. So far ALE has been applied to rather few materials, but, in principle, it could have a quite general application. It has been used to prepare single-crystal overlayers of CdTe, (Cd,Mn)Te, GaAs and AlAs, a number of polycrystalline films and highly efficient electroluminescent thin-film displays based on ZnS:Mn. It could also offer particular advantages for the preparation of ultrathin films of precisely controlled thickness in the nanometer range and thus may have a special value for growing low-dimensional structures.

  3. Stereotactic Irradiation of the Postoperative Resection Cavity for Brain Metastasis: A Frameless Linear Accelerator-Based Case Series and Review of the Technique

    SciTech Connect

    Kelly, Paul J.; Alexander, Brian M.; Hacker, Fred; Marcus, Karen J.; Weiss, Stephanie E.

    2012-01-01

    Purpose: Whole-brain radiation therapy (WBRT) is the standard of care after resection of a brain metastasis. However, concern regarding possible neurocognitive effects and the lack of survival benefit with this approach has led to the use of stereotactic radiosurgery (SRS) to the resection cavity in place of WBRT. We report our initial experience using an image-guided linear accelerator-based frameless stereotactic system and review the technical issues in applying this technique. Methods and Materials: We retrospectively reviewed the setup accuracy, treatment outcome, and patterns of failure of the first 18 consecutive cases treated at Brigham and Women's Hospital. The target volume was the resection cavity without a margin excluding the surgical track. Results: The median number of brain metastases per patient was 1 (range, 1-3). The median planning target volume was 3.49 mL. The median prescribed dose was 18 Gy (range, 15-18 Gy) with normalization ranging from 68% to 85%. In all cases, 99% of the planning target volume was covered by the prescribed dose. The median conformity index was 1.6 (range, 1.41-1.92). The SRS was delivered with submillimeter accuracy. At a median follow-up of 12.7 months, local control was achieved in 16/18 cavities treated. True local recurrence occurred in 2 patients. No marginal failures occurred. Distant recurrence occurred in 6/17 patients. Median time to any failure was 7.4 months. No Grade 3 or higher toxicity was recorded. A long interval between initial cancer diagnosis and the development of brain metastasis was the only factor that trended toward a significant association with the absence of recurrence (local or distant) (log-rank p = 0.097). Conclusions: Frameless stereotactic irradiation of the resection cavity after surgery for a brain metastasis is a safe and accurate technique that offers durable local control and defers the use of WBRT in select patients. This technique should be tested in larger prospective studies.

  4. About the atomic structures of icosahedral quasicrystals

    NASA Astrophysics Data System (ADS)

    Quiquandon, Marianne; Gratias, Denis

    2014-01-01

    This paper is a survey of the crystallographic methods that have been developed these last twenty five years to decipher the atomic structures of the icosahedral stable quasicrystals since their discovery in 1982 by D. Shechtman. After a brief recall of the notion of quasiperiodicity and the natural description of Z-modules in 3-dim as projection of regular lattices in N>3-dim spaces, we give the basic geometrical ingredients useful to describe icosahedral quasicrystals as irrational 3-dim cuts of ordinary crystals in 6-dim space. Atoms are described by atomic surfaces (ASs) that are bounded volumes in the internal (or perpendicular) 3-dim space and the intersections of which with the physical space are the actual atomic positions. The main part of the paper is devoted to finding the major properties of quasicrystalline icosahedral structures. As experimentally demonstrated, they can be described with a surprisingly few high symmetry ASs located at high symmetry special points in 6-dim space. The atomic structures are best described by aggregations and intersections of high symmetry compact interpenetrating atomic clusters. We show here that the experimentally relevant clusters are derived from one generic cluster made of two concentric triacontahedra scaled by τ and an external icosidodecahedron. Depending on which ones of the orbits of this cluster are eventually occupied by atoms, the actual atomic clusters are of type Bergman, Mackay, Tsai and others….

  5. Defect-free atom arrays on demand

    NASA Astrophysics Data System (ADS)

    Levine, Harry; Bernien, Hannes; Keesling, Alex; Anschuetz, Eric; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Endres, Manuel; Lukin, Mikhail

    2016-05-01

    Arrays of neutral, trapped atoms have proven to be an extraordinary platform for studying quantum many-body physics and implementing quantum information protocols. Conventional approaches to generate such arrays rely on loading atoms into optical lattices and require elaborate experimental control. An alternative, simpler approach is to load atoms into individual optical tweezers. However, the probabilistic nature of the loading process limits the size of the arrays to small numbers of atoms. Here we present a new method for assembling defect-free arrays of large numbers of atoms. Our technique makes use of an array of tightly focused optical tweezers generated by an acousto-optic deflector. The positions of the traps can be dynamically reconfigured on a sub-millisecond timescale. With single-site resolved fluorescence imaging, we can identify defects in the atom array caused by the probabilistic loading process and rearrange the trap positions in response. This will enable us to generate defect-free atom arrays on demand. We discuss our latest results towards reaching this goal along with schemes to implement long-range interactions between atoms in the array. Now at Caltech.

  6. Defect-free atom arrays on demand

    NASA Astrophysics Data System (ADS)

    Bernien, Hannes; Keesling, Alexander; Levine, Harry; Anschuetz, Eric; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Endres, Manuel; Lukin, Mikhail D.

    2016-05-01

    Arrays of neutral, trapped atoms have proven to be an extraordinary platform for studying quantum many-body physics and implementing quantum information protocols. Conventional approaches to generate such arrays rely on loading atoms into optical lattices and require elaborate experimental control. An alternative, simpler approach is to load atoms into individual optical tweezers. However, the probabilistic nature of the loading process limits the size of the arrays to small numbers of atoms. Here we present a new method for assembling defect-free arrays of large numbers of atoms. Our technique makes use of an array of tightly focused optical tweezers generated by an acousto-optic deflector. The positions of the traps can be dynamically reconfigured on a sub-millisecond timescale. With single-site resolved fluorescence imaging, we can identify defects in the atom array caused by the probabilistic loading process and rearrange the trap positions in response. This will enable us to generate defect-free atom arrays on demand. We discuss our latest results towards reaching this goal along with schemes to implement long-range interactions between atoms in the array.

  7. PSI for Low-Enrollment Junior-Senior Physics Courses

    ERIC Educational Resources Information Center

    Frahm, Charles P.; Young, Robert D.

    1976-01-01

    The administration of a Personalized System of Instruction (PSI) for junior-senior level courses in mechanics, electricity and magneturn, atomic physics, mathematical physics, physics and computers, astrophysics, and relativity is described. (CP)

  8. Physics Division annual review, April 1, 1991--March 31, 1992

    SciTech Connect

    Henning, W.F.

    1992-08-01

    This report contains brief discusses on topics in the following areas: Research at atlas; operation and development of atlas; medium-energy nuclear physics and weak interactions; theoretical nuclear physics; and atomic and molecular physics research.

  9. Multilevel Atomic Coherent States and Atomic Holomorphic Representation

    NASA Technical Reports Server (NTRS)

    Cao, Chang-Qi; Haake, Fritz

    1996-01-01

    The notion of atomic coherent states is extended to the case of multilevel atom collective. Based on atomic coherent states, a holomorphic representation for atom collective states and operators is defined. An example is given to illustrate its application.

  10. Advances in Atomic Gyroscopes: A View from Inertial Navigation Applications

    PubMed Central

    Fang, JianCheng; Qin, Jie

    2012-01-01

    With the rapid development of modern physics, atomic gyroscopes have been demonstrated in recent years. There are two types of atomic gyroscope. The Atomic Interferometer Gyroscope (AIG), which utilizes the atomic interferometer to sense rotation, is an ultra-high precision gyroscope; and the Atomic Spin Gyroscope (ASG), which utilizes atomic spin to sense rotation, features high precision, compact size and the possibility to make a chip-scale one. Recent developments in the atomic gyroscope field have created new ways to obtain high precision gyroscopes which were previously unavailable with mechanical or optical gyroscopes, but there are still lots of problems that need to be overcome to meet the requirements of inertial navigation systems. This paper reviews the basic principles of AIG and ASG, introduces the recent progress in this area, focusing on discussing their technical difficulties for inertial navigation applications, and suggests methods for developing high performance atomic gyroscopes in the near future. PMID:22778644

  11. PREFACE: 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"

    NASA Astrophysics Data System (ADS)

    Yamada, Taiichi; Kanada-En'yo, Yoshiko

    2014-12-01

    (Research Center for Nuclear Physics, Osaka University), CNS (Center for Nuclear Study, University of Tokyo), JICFuS (Joint Institute for Computational Fundamental Science), and RIKEN (Nishina Center for Accelerator-Based Science, Institute of Physical and Chemical Research). This workshop was supported by Yokohama Convention & Visitors Bureau and Kanto Gakuin University. It remains to be announced that the next, the fourth in this series of SOTANCP workshops, SOTANCP4, will be held in Galveston, Texas, USA, in 2018.

  12. SPARC: The Stored Particle Atomic Research Collaboration At FAIR

    SciTech Connect

    Stoehlker, Th.; Beyer, H. F.; Braeuning-Demian, A.; Brandau, C.; Herfurth, F.; Kozhuharov, Ch.; Kuehl, Th.; Liesen, D.; Litvinov, Yu.; Noertershaeuser, W.; Kester, O.; Quint, W.; Spillmann, U.; Winters, D.; Gumberidze, A.; Grisenti, R. E.; Petridis, N.; Hagmann, S.; Maertin, R.; Schramm, U.

    2011-06-01

    The future international accelerator Facility for Antiproton and Ion Research (FAIR) encompasses 4 scientific pillars containing at this time 14 approved technical proposals worked out by more than 2000 scientists from all over the world. They offer a wide range of new and challenging opportunities for atomic physics research in the realm of highly-charged heavy ions and exotic nuclei. As one of the backbones of the Atomic, Plasma Physics and Applications (APPA) pillar, the Stored Particle Atomic Physics Research Collaboration (SPARC) has organized tasks and activities in various working groups for which we will present a concise survey on their current status.

  13. Submillimetre observations of atomic carbon

    NASA Technical Reports Server (NTRS)

    Phillips, T. G.; Keene, J.

    1982-01-01

    Emission from the ground state fine structure transition of atomic carbon at 610 microns has been observed in Galactic sources. From comparison of the observations with CO emission, it can be deduced that the abundance of neutral carbon relative to CO is high (approximately 0.1-3). The spatial and velocity distribution of CI and CO are often very similar. If molecular clouds are older than 1 x 10 to the 6th power years, the observations necessitate a mechanism which can maintain a high abundance of neutral carbon in cloud material, either by hindering complete conversion of C into CO or by physically and chemically rejuvenating the material.

  14. Research accomplishments and future goals in particle physics

    SciTech Connect

    Not Available

    1990-11-30

    This document presents our proposal to continue the activities of Boston University researchers in high energy physics research. We have a broad program of participation in both non-accelerator and accelerator-based efforts. High energy research at Boston University has a special focus on the physics program of the Superconducting Supercollider. We are active in research and development for detector subsystems, in the design of experiments, and in study of the phenomenology of the very high energy interactions to be observed at the SSC. The particular areas discussed in this paper are: colliding beams physics; accelerator design physics; MACRO project; proton decay project; theoretical particle physics; muon G-2 project; fast liquid scintillators; SSCINTCAL project; TRD project; massively parallel processing for the SSC; and physics analysis and vertex detector upgrade at L3.

  15. Properties of atoms in molecules: Transition probabilities

    NASA Astrophysics Data System (ADS)

    Bader, R. F. W.; Bayles, D.; Heard, G. L.

    2000-06-01

    The transition probability for electric dipole transitions is a measurable property of a system and is therefore, partitionable into atomic contributions using the physics of a proper open system. The derivation of the dressed property density, whose averaging over an atomic basin yields the atomic contribution to a given oscillator strength, is achieved through the development of perturbation theory for an open system. A dressed density describes the local contribution resulting from the interaction of a single electron at some position r, as determined by the relevant observable, averaged over the motions of all of the remaining particles in the system. In the present work, the transition probability density expressed in terms of the relevant transition density, yields a local measure of the associated oscillator strength resulting from the interaction of the entire molecule with a radiation field. The definition of the atomic contributions to the oscillator strength enables one to determine the extent to which a given electronic or vibrational transition is spatially localized to a given atom or functional group. The concepts introduced in this article are applied to the Rydberg-type transitions observed in the electronic excitation of a nonbonding electron in formaldehyde and ammonia. The atomic partitioning of the molecular density distribution and of the molecular properties by surfaces of zero flux in the gradient vector field of the electron density, the boundary condition defining the physics of a proper open system, is found to apply to the density distributions of the excited, Rydberg states.

  16. Topologically Reconfigurable Atomic Lattice Quantum Metamaterial

    NASA Astrophysics Data System (ADS)

    Jha, Pankaj; Mrejen, Michael; Kim, Jeongmin; Wu, Chihhui; Wang, Yuan; Rostovtsev, Yuri; Zhang, Xiang

    Metamaterials have attracted unprecedented attention owing to their exceptional light-matter interaction properties. However, harnessing metamaterial at single photon or few photon excitations is still a long way to go due to several critical challenges such as optical loss, defects to name a few. Here we introduce and theoretically demonstrate a novel platform toward quantum metamaterial, immune to aforementioned challenges, with ultra-cold neutral atoms trapped in an artificial crystal of light. Such periodic atomic density grating -an atomic lattice- exhibits extreme anisotropic optical response where it behaves like a metal in one direction but dielectric along orthogonal directions. We harness the interacting dark resonance physics to eliminate the absorption loss and demonstrate an all-optical and ultra-fast control over the photonic topological transition from a close to an open topology at the same frequency. Such atomic lattice quantum metamaterial enables dynamic manipulation of the decay rate of a quantum emitter by more than an order of magnitude. Our proposal brings together two important contemporary realm of science - cold atom physics and metamaterial for applications in both fundamental and applied science. Atomic lattice quantum metamaterial may provide new opportunities, at single or few photon level, for quantum sensing, quantum information processing with metamaterials.

  17. ATOMIC AND MOLECULAR PHYSICS: Interference Angle on Quantum Rotational Energy Transfer in Na + Na2 (A1 Σ+u, v = 8 ~ b3п0u, v = 14) Molecular Collision System

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Li; Miao, Gang; Li, Jian; Ma, Feng-Cai

    2009-12-01

    In order to study the collisional quantum interference (CQI) on rotational energy transfer in atom-diatom system, we have studied the relation of the integral interference angle and differential interference angle in Na + Na2 (A1 σ+u, v = 8 ~ b3п0u, v = 14) collision system. In this paper, based on the first-Born approximation of time-dependent perturbation theory and taking into accounts the anisotropic effect of Lennard-Jones interaction potentials, we present a theoretical model of collisional quantum interference in intramolecular rotational energy transfer, and a relationship between differential and integral interference angles.

  18. A Guidebook for Teaching Physics.

    ERIC Educational Resources Information Center

    Yurkewicz, William, Jr.

    This guidebook consists of 11 chapters. Chapter 1 provides information on organizing a physics course, considering such topics as types of physics programs, laboratory work, curriculum selection, and computers/calculators. Chapters 2 to 11 focus, respectively, on the topic areas of forces, motion, dynamics, energy, heat, the atomic structure of…

  19. Physics Data Booklet (Revised 1987).

    ERIC Educational Resources Information Center

    Alberta Dept. of Education, Edmonton.

    This booklet was designed as a reference for teachers and students of physics on various types of data. Included are: (1) formulas for various constants involved in the study of gravity, electricity, magnetism, atomic physics, particles, and trigonometry; (2) a chart containing values of trigometric functions; (3) equations used in the study of…

  20. Reflection Spectrum of Two Level Atoms by an Evanescent Laser Wave

    NASA Technical Reports Server (NTRS)

    Tan, Weihan; Li, Qingning

    1996-01-01

    An exact solution and numerical calculation of the reflection of two level atoms by atomic mirror are presented. The curve of reflection coefficient against Rabi frequency calculated shows some new features, and the physical machanism underlying is analyzed.