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. Accelerator-based techniques for the support of senior-level undergraduate physics laboratories

    NASA Astrophysics Data System (ADS)

    Williams, J. R.; Clark, J. C.; Isaacs-Smith, T.

    2001-07-01

    Approximately three years ago, Auburn University replaced its aging Dynamitron accelerator with a new 2MV tandem machine (Pelletron) manufactured by the National Electrostatics Corporation (NEC). This new machine is maintained and operated for the University by Physics Department personnel, and the accelerator supports a wide variety of materials modification/analysis studies. Computer software is available that allows the NEC Pelletron to be operated from a remote location, and an Internet link has been established between the Accelerator Laboratory and the Upper-Level Undergraduate Teaching Laboratory in the Physics Department. Additional software supplied by Canberra Industries has also been used to create a second Internet link that allows live-time data acquisition in the Teaching Laboratory. Our senior-level undergraduates and first-year graduate students perform a number of experiments related to radiation detection and measurement as well as several standard accelerator-based experiments that have been added recently. These laboratory exercises will be described, and the procedures used to establish the Internet links between our Teaching Laboratory and the Accelerator Laboratory will be discussed.

  7. PHYSICS: Toward Atom Chips.

    PubMed

    Fortágh, József; Zimmermann, Claus

    2005-02-11

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

  8. 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)

  9. 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…

  10. Bringing Atoms into First-Year Physics.

    ERIC Educational Resources Information Center

    Chabay, Ruth W.; Sherwood, Bruce A.

    1999-01-01

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

  11. Atomic physics in strong fields

    SciTech Connect

    Chu, Shih-I.

    1992-04-01

    This report discusses: Microwave Driven Multiphoton Excitation Dynamics in Rydberg Atoms; Nonadiabatic Geometric Phases of Multiphoton Transitions in Dissipative Systems and Spin-j Systems; and Nonperturbative Treatments of Atomic and Molecular Processes in Intense Laser Fields.

  12. 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.

  13. 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.

  14. 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.

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

    PubMed

    El-Sherbini, Tharwat M

    2015-09-01

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

  16. 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.

  17. 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

  18. Scattering processes in atomic physics, nuclear physics, and cosmology

    NASA Astrophysics Data System (ADS)

    Shchedrin, Gavriil

    The universal way to probe a physical system is to scatter a particle or radiation off the system. The results of the scattering are governed by the interaction Hamiltonian of the physical system and scattered probe. An object of the investigation can be a hydrogen atom immersed in a laser field, heavy nucleus exposed to a flux of neutrons, or space-time metric perturbed by the stress-energy tensor of neutrino flux in the early Universe. This universality of scattering process designates the Scattering Matrix, defined as the unitary matrix of the overlapping in and out collision states, as the central tool in theoretical physics. In this Thesis we present our results in atomic physics, nuclear physics, and cosmology. In these branches of theoretical physics the key element that unifies all of them is the scattering matrix. Additionally, within the scope of Thesis we present underlying ideas responsible for the unification of various physical systems. Within atomic physics problems, namely the axial anomaly contribution to parity nonconservation in atoms, and two-photon resonant transition in a hydrogen atom, it was the scattering matrix which led to the Landau-Yang theorem, playing the central role in these problems. In scattering problems of cosmology and quantum optics we developed and implemented mathematical tools that allowed us to get a new point of view on the subject. Finally, in nuclear physics we were able to take advantage of the target complexity in the process of neutron scattering which led to the formulation of a new resonance width distribution for an open quantum system.

  19. (Atomic collisions in solid and plasma physics)

    SciTech Connect

    Robinson, M.T.

    1989-09-05

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

  20. 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.

  1. 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.

  2. The 12th International Conference on Atomic Physics

    NASA Astrophysics Data System (ADS)

    Lewis, Robert R.; Rich, Arthur

    1991-02-01

    The conference began with a session devoted to the Nobel Laureates in Physics for 1989, all of whom were from the Atomic Physics community; Norman Ramsey and Hans Dehmelt spoke but Wolfgang Paul was unable to attend. Some sessions were titled as follows: Fundamental Laws and Constants; Atom and Ion Manipulation; Nonlinear Physics and Chaos; Quantum Optics and Other Laser Techniques; Photoionization Processes; Plasma Physics; Atomic Spectroscopy and Structure - Theory; Atomic Spectroscopy and Structure - Experimental; Molecular Spectroscopy and Structure, Surfaces, and Clusters; Atomic, Ionic, and Molecular Collisions; Electron and Positron Collisions; and Exotic Atomic and Special Topics.

  3. Atomic physics and quantum optics using superconducting circuits.

    PubMed

    You, J Q; Nori, Franco

    2011-06-29

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

  4. Atomic physics in strong fields. Progress report

    SciTech Connect

    Chu, Shih-I

    1992-04-01

    This report discusses: Microwave Driven Multiphoton Excitation Dynamics in Rydberg Atoms; Nonadiabatic Geometric Phases of Multiphoton Transitions in Dissipative Systems and Spin-j Systems; and Nonperturbative Treatments of Atomic and Molecular Processes in Intense Laser Fields.

  5. Experiments in atomic and applied physics using synchrotron radiation

    SciTech Connect

    Jones, K.W.

    1987-01-01

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

  6. 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…

  7. 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.

  8. 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

  9. 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…

  10. 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.

  11. 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

  12. Theoretical Atomic Physics code development IV: LINES, A code for computing atomic line spectra

    SciTech Connect

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

    1988-12-01

    A new computer program, LINES, has been developed for simulating atomic line emission and absorption spectra using the accurate fine structure energy levels and transition strengths calculated by the (CATS) Cowan Atomic Structure code. Population distributions for the ion stages are obtained in LINES by using the Local Thermodynamic Equilibrium (LTE) model. LINES is also useful for displaying the pertinent atomic data generated by CATS. This report describes the use of LINES. Both CATS and LINES are part of the Theoretical Atomic PhysicS (TAPS) code development effort at Los Alamos. 11 refs., 9 figs., 1 tab.

  13. 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.

  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. 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,…

  16. 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)

  17. 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)

  18. NASA GSFC Science Symposium on Atomic and Molecular Physics

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand K. (Editor)

    2007-01-01

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

  19. ATOMIC AND MOLECULAR PHYSICS: Dynamic splitting and merging of an atom cloud on an atom chip

    NASA Astrophysics Data System (ADS)

    Ke, Min; Yan, Bo; Cheng, Feng; Wang, Yu-Zhu

    2009-11-01

    Chip-based atom interferometers bring together the advantages of atom chips and Bose-Einstein condensates. Their central prerequisite is that a condensate can be coherently split into two halves with a determined relative phase. This paper demonstrates the dynamical splitting and merging of an atom cloud with two U-wires on an atom chip. Symmetrical and asymmetrical splittings are realized by applying a bias field with different directions and magnitudes. The trajectories of the splitting are consistent with theoretical calculations. The atom chip is a good candidate for constructing an atom interferometer.

  20. Atomic physics requirements in fusion research

    NASA Astrophysics Data System (ADS)

    Behringer, Kurt

    2000-11-01

    Nuclear fusion research, using magnetically confined plasmas, needs a great amount of atomic data in the fields of plasma diagnostics, plasma spectroscopy and modelling. Conventional spectroscopy and some specialised techniques are being used for analysing plasma behavior and plasma composition. Hydrogen data are required, as well as coefficients for impurities originating from the vacuum vessel walls and protection tiles. Some noble gases are being used for radiative cooling or transport studies of highly ionized ions. For measuring metal concentrations, diagnostic lines from the plasma interior are recorded, sometimes of highly ionized species like Zn-like tungsten. The ionization balance and the emitting shells must be calculated on the basis of the relevant atomic data and of the transport coefficients. For high heat-load areas, carbon is mostly used at present, which is fully ionized in the plasma and can only be measured by charge-exchange recombination spectroscopy. Impurity particle influxes at the boundary are derived from lines of neutrals or low ionization stages, a method, which can also be extended to the band emission of molecules. In this way, chemical erosion of carbon is being investigated. In cold divertor plasmas, hydrogen molecules also play some role, e.g. enhancing hydrogen ion recombination. In addition to the usual coefficients for ionization, recombination, charge exchange and radiation for all relevant elements, molecular data are required in model calculations of the plasma boundary and of divertors. Some examples of interpretation methods and experimental results in these fields are presented. .

  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. 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.

  5. 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.

  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. Applications of B-splines in atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Bachau, H.; Cormier, E.; Decleva, P.; Hansen, J. E.; Martín, F.

    2001-12-01

    One of the most significant developments in computational atomic and molecular physics in recent years has been the introduction of B-spline basis sets in calculations of atomic and molecular structure and dynamics. B-splines were introduced in applied mathematics more than 50 years ago, but it has been in the 1990s, with the advent of powerful computers, that the number of applications has grown exponentially. In this review we present the main properties of B-splines and discuss why they are useful to solve different problems in atomic and molecular physics. We provide an extensive reference list of theoretical works that have made use of B-spline basis sets up to 2000. Among these, we have focused on those applications that have led to the discovery of new interesting phenomena and pointed out the reasons behind the success of the approach.

  8. 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,…

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

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

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

  10. ATOMIC PHYSICS, 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…

  11. 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.

  12. 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.

  13. Theoretical atomic physics code development at Los Alamos

    SciTech Connect

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

    1989-01-01

    We have developed a set of computer codes for atomic physics calculations at Los Alamos. These codes can calculate a large variety of data with a minimum of effort on the part of the user. In particular, differential cross sections and electron impact coherence parameters can be readily obtained for arbitrary ions or atoms. Currently, the theory consists of non-relativistic Hartree-Fock structure calculations and non relativistic distorted wave approximation or first order many body theory collisional calculations. 12 refs., 2 figs., 5 tabs.

  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. 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

  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. Atomic Physics with Ultra-Slow/Trapped Antiprotons

    SciTech Connect

    Yamazaki, Yasunori

    2005-03-17

    Recently, slow and ultra-slow antiprotons are now available, which will open a new field of research in atomic physics as well as in related fields. In realizing this, the combination of an RFQD (Radio Frequency Quadrupole Decelerator) and a large multi-ring trap (MRT) installed in a super-conducting solenoid has been employed. Several million antiprotons have already been accumulated, and a mono-energetic antiproton beam of 10 eV has been extracted and transported through a specially designed beam line. A couple of basic experiments which get feasible by the developments of ultra slow antiproton beam are discussed, which include ionization and antiprotonic atom formation processes and also to study spectroscopic nature of various meta-stable antiprotonic atoms under single collision conditions. A so-called cusp trap configuration is also discussed, which could for the first time synthesize intense spin-polarized antihydrogen beams. At the same time, it could trap antihydrogen atoms for a macroscopic time.

  19. 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.

  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. Integrated physics package of a chip-scale atomic clock

    NASA Astrophysics Data System (ADS)

    Li, Shao-Liang; Xu, Jing; Zhang, Zhi-Qiang; Zhao, Lu-Bing; Long, Liang; Wu, Ya-Ming

    2014-07-01

    The physics package of a chip-scale atomic clock (CSAC) has been successfully realized by integrating vertical cavity surface emitting laser (VCSEL), neutral density (ND) filter, λ/4 wave plate, 87Rb vapor cell, photodiode (PD), and magnetic coil into a cuboid metal package with a volume of about 2.8 cm3. In this physics package, the critical component, 87Rb vapor cell, is batch-fabricated based on MEMS technology and in-situ chemical reaction method. Pt heater and thermistors are integrated in the physics package. A PTFE pillar is used to support the optical elements in the physics package, in order to reduce the power dissipation. The optical absorption spectrum of 87Rb D1 line and the microwave frequency correction signal are successfully observed while connecting the package with the servo circuit system. Using the above mentioned packaging solution, a CSAC with short-term frequency stability of about 7 × 10-10 τ-1/2 has been successfully achieved, which demonstrates that this physics package would become one promising solution for the CSAC.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    SciTech Connect

    Armstrong, Jr., Lloyd

    1997-09-21

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

  5. 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.

  6. 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.

  7. 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.

  8. Quantum Hall physics with cold atoms in cylindrical optical lattices

    NASA Astrophysics Data System (ADS)

    Łåcki, Mateusz; Pichler, Hannes; Sterdyniak, Antoine; Lyras, Andreas; Lembessis, Vassilis E.; Al-Dossary, Omar; Budich, Jan Carl; Zoller, Peter

    2016-01-01

    We propose and study various realizations of a Hofstadter-Hubbard model on a cylinder geometry with fermionic cold atoms in optical lattices. The cylindrical optical lattice is created by copropagating Laguerre-Gauss beams, i.e., light beams carrying orbital angular momentum. By strong focusing of the light beams we create a real-space optical lattice in the form of rings, which are offset in energy. A second set of Laguerre-Gauss beams then induces a Raman-hopping between these rings, imprinting phases corresponding to a synthetic magnetic field (artificial gauge field). In addition, by rotating the lattice potential, we achieve a slowly varying flux through the hole of the cylinder, which allows us to probe the Hall response of the system as a realization of Laughlin's thought experiment. We study how in the presence of interactions fractional quantum Hall physics could be observed in this setup.

  9. The Los Alamos suite of relativistic atomic physics codes

    SciTech Connect

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

    2015-05-28

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

  10. The Los Alamos suite of relativistic atomic physics codes

    DOE PAGES

    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

  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 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.

  13. Self-assembly and physical properties of atomic aggregates

    NASA Astrophysics Data System (ADS)

    Berber, Savas

    In this Thesis, I present a study of nanoscaled atomic aggregates such as fullerenes, nanotubes, diamondoids, and related materials. Nanotubes and fullerenes, which could be formed of any layered material, show unusual physical properties due to their lower dimensionality and nanometer size. I have investigated the microscopic self-assembly mechanisms and the physical properties of these nanoscale atomic aggregates through computer simulations primarily by using molecular dynamics simulations combined with structure optimization and total energy calculations. First, I determined the stability, optimum geometry and electronic properties of nanometer-sized capped graphitic cones, called "nanohorns". My main result, simulated scanning tunneling microscopy images of the various structures at different bias voltages, indicate a net electron transfer towards the pentagon vertex sites. Next, I investigated the absorption of fullerenes in a nanotube during a hierarchical self-assembly of "nanopeapods". I found the absorption through a defect to be significantly more efficient than the end-on absorption. I also investigated the energetics and detailed fusion mechanism of fullerenes inside a carbon nanotube. I found that fullerenes are pulled in by a "capillary" force, which yields an effective GPa pressure. Fusion of fullerenes continues along the minimum energy path as a sequence of Stone-Wales transformations. I have further investigated the microscopic dislocation mechanism leading to structural transformations in nanostructures. In particular, I studied the relative stability and the conversion mechanism between multi-wall carbon nanotubes and graphitic scrolls. I postulated a zipper-like mechanism, which converts a scroll to the more stable multiwall nanotube. I also found this transformation to proceed very efficiently due to the unusually low associated activation barrier. A further study related to defects in nanoscale systems involves the response of defective

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

    ERIC Educational Resources Information Center

    DETERLINE, WILLIAM A.; KLAUS, DAVID J.

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

  15. Physical methods in nanoscale science with the atomic force microscope

    NASA Astrophysics Data System (ADS)

    Schaffer, Tilman Erich

    1998-12-01

    The atomic force microscope (AFM) has opened up a wide gate to the nanoscopic world. Since its invention twelve years ago, it has allowed researchers to advance to new science. The extent of this advancement is strongly coupled to the sophistication of AFM instrumentation and to the methods with which AFMs are used. New AFMs and methods are needed to push the limits. Chapter 1 and 2 introduce such new AFMs with low-noise and high-speed characteristics. The AFM presented in Chapter 2 has a focused spot size of 1.6 m m in diameter and is capable of using cantilevers much smaller than previously possible. Chapter 3 discusses the physics of the detection system and gives methods for improving the detection sensitivity. Thermal motion of the cantilever, usually contributing to the noise in a measurement, is a method for probing the oscillatory hydration potential at a calcite-water interface in Chapter 4. Chapter 5 establishes a method of measuring the three-dimensional electromagnetic field over a surface and comparing the data to micro-magnetic models. Biomineralization of marine abalone nacre is the subject of interdisciplinary Chapter 6, where a variety of microscopic and statistical methods distinguish between two competing models of nacre growth.

  16. ATOMIC AND MOLECULAR PHYSICS: Surface-induced evaporative cooling

    NASA Astrophysics Data System (ADS)

    Ke, Min; Yan, Bo; Cheng, Feng; Wang, Yu-Zhu

    2009-10-01

    The effects of surface-induced evaporative cooling on an atom chip are investigated. The evolutions of temperature, number and phase-space density of the atom cloud are measured when the atom cloud is brought close to the surface. Rapid decrease of the temperature and number of the atoms is found when the atom-surface distance is < 100 μm. A gain of about a factor of five on the phase-space density is obtained. It is found that the efficiency of the surface-induced evaporative cooling depends on the atom-surface distance and the shape of the evaporative trap. When the atoms are moved very close to the surface, severe heating is observed, which dominates when the holding time is > 8 ms. It is important that the surface-induced evaporative cooling offers novel possibilities for the realization of a continuous condensation, where a spatially varying evaporative cooling is required.

  17. ATOMIC AND MOLECULAR PHYSICS: Lifetime Measurement of Cold Atoms in an Integrating Sphere

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Zhuo; Wang, Xu-Cheng; Cheng, Hua-Dong; Xiao, Ling; Liu, Liang; Wang, Yu-Zhu

    2009-08-01

    We present an experimental measurement of the lifetime of the cold 87Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the integrating sphere. Our result shows that the lifetime is primarily determined by the free fall of the cold 87Rb atoms, and its half-life can reach 40 ms, which is suitable for many experiments, especially for a cold atom clock.

  18. 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

  19. Semiclassical atom theory applied to solid-state physics

    NASA Astrophysics Data System (ADS)

    Constantin, Lucian A.; Terentjevs, Aleksandrs; Della Sala, Fabio; Cortona, Pietro; Fabiano, Eduardo

    2016-01-01

    Using the semiclassical neutral atom theory, we extend to fourth order the modified gradient expansion of the exchange energy of density functional theory. This expansion can be applied both to large atoms and solid-state problems. Moreover, we show that it can be employed to construct a simple and nonempirical generalized gradient approximation (GGA) exchange-correlation functional competitive with state-of-the-art GGAs for solids, but also reasonably accurate for large atoms and ordinary chemistry.

  20. 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.

  1. ATOMIC AND MOLECULAR PHYSICS: Kinetic theory of (2 + 4)-level atom in σ+ - σ- laser fields

    NASA Astrophysics Data System (ADS)

    Yu, Chuang; Yu, De-Shui; Chen, Jing-Biao

    2009-08-01

    The kinetic theory of (2 + 4)-level atoms in σ + - σ- laser fields is presented. We systemically discuss friction coefficient, momentum diffusion tensor and atomic temperature based on the Fokker-Planck equation. This cooling system is much like that of a (1 + 3)-level atom, and the temperature is still limited to the Doppler temperature. Since this cooling system has not been investigated before, this work may be regarded as a necessary complement to the laser cooling theory.

  2. 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.

  3. 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…

  4. ATOMIC AND MOLECULAR PHYSICS: Realization of Green MOT for Ytterbium Atoms

    NASA Astrophysics Data System (ADS)

    Zhao, Peng-Yii; Xiong, Zhuan-Xian; Long, Yun; He, Ling-Xiang; Lü, Bao-Long

    2009-08-01

    We report the experimental realization of a magneto-optical trap (MOT) of 174Yb atoms operating on the 1So-3 P1 intercombination transition at 555.8 nm. The green MOT is loaded by a Zeeman-slowed atomic beam. In order to increase the capture velocity of the MOT, we use the trapping laser beams consisting of five discrete frequency components obtained by modulating the laser light through an electro-optic modulator. The trapped atomic number of the 174Yb isotope is about 6.2 × 105, and the temperature of the cold atomic cloud is estimated to be about 100 μK. The success of the green MOT is an important step towards the goal of an ytterbium optical clock.

  5. 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.

  6. Dynamical overstability of radiative blast waves: the atomic physics of shock stability.

    PubMed

    Laming, J Martin; Grun, Jacob

    2002-09-16

    Atomic-physics calculations of radiative cooling are used to develop criteria for the overstability of radiating shocks. Our calculations explain the measurement of shock overstability by Grun et al. [Phys. Rev. Lett. 66, 2738 (1991)

  7. 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.

  8. Internal and external atomic steps in graphite exhibit dramatically different physical and chemical properties.

    PubMed

    Lee, Hyunsoo; Lee, Han-Bo-Ram; Kwon, Sangku; Salmeron, Miquel; Park, Jeong Young

    2015-04-28

    We report on the physical and chemical properties of atomic steps on the surface of highly oriented pyrolytic graphite (HOPG) investigated using atomic force microscopy. Two types of step edges are identified: internal (formed during crystal growth) and external (formed by mechanical cleavage of bulk HOPG). The external steps exhibit higher friction than the internal steps due to the broken bonds of the exposed edge C atoms, while carbon atoms in the internal steps are not exposed. The reactivity of the atomic steps is manifested in a variety of ways, including the preferential attachment of Pt nanoparticles deposited on HOPG when using atomic layer deposition and KOH clusters formed during drop casting from aqueous solutions. These phenomena imply that only external atomic steps can be used for selective electrodeposition for nanoscale electronic devices.

  9. 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…

  10. 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.

  11. ATOMIC AND MOLECULAR PHYSICS: Four-parameter analytical local model potential for atoms

    NASA Astrophysics Data System (ADS)

    Yu, Fei; Sun, Jiu-Xun; Tian, Rong-Gang; Yang, Wei

    2009-10-01

    Analytical local model potential for modeling the interaction in an atom reduces the computational effort in electronic structure calculations significantly. A new four-parameter analytical local model potential is proposed for atoms Li through Lr, and the values of four parameters are shell-independent and obtained by fitting the results of Xa method. At the same time, the energy eigenvalues, the radial wave functions and the total energies of electrons are obtained by solving the radial Schrödinger equation with a new form of potential function by Numerov's numerical method. The results show that our new form of potential function is suitable for high, medium and low Z atoms. A comparison among the new potential function and other analytical potential functions shows the greater flexibility and greater accuracy of the present new potential function.

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

    PubMed

    Taylor, Kenneth T

    2002-06-15

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

  13. 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.

  14. ATOMIC AND MOLECULAR PHYSICS: Bose-Einstein condensation on an atom chip

    NASA Astrophysics Data System (ADS)

    Yan, Bo; Cheng, Feng; Ke, Min; Li, Xiao-Lin; Tang, Jiu-Yao; Wang, Yu-Zhu

    2009-10-01

    This paper reports an experiment of creating Bose-Einstein condensate (BEC) on an atom chip. The chip-based Z-wire current with a homogeneous bias magnetic field creates a tight magnetic trap, which allows for a fast production of BEC. After a 4.17-s forced radio frequency evaporative cooling, a condensate with about 3000 atoms appears. The transition temperature is about 300 nK. This compact system is quite robust, allowing for versatile extensions and further studying of BEC.

  15. ATOMIC AND MOLECULAR PHYSICS: Lithium atom population transfer by population trapping in a chirped microwave pulse

    NASA Astrophysics Data System (ADS)

    Jia, Guang-Rui; Zhang, Xian-Zhou; Ren, Zhen-Zhong; Wu, Su-Ling

    2009-12-01

    Using a time-dependent multilevel approach, we demonstrate that lithium atoms can be transferred to states of lower principle quantum number by exposing them to a frequency chirped microwave pulse. The population transfer from n = 79 to n = 70 states of lithium atoms with more than 80% efficiency is achieved by means of the sequential two-photon Δn = -1 transitions. It is shown that the coherent control of the population transfer can be accomplished by the optimization of the chirping parameters and microwave field strength. The calculation results agree well with the experimental ones and novel explanations have been given to understand the experimental results.

  16. 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)

  17. Hybrid atom-nanophotonic lattices for quantum optics and many-body physics

    NASA Astrophysics Data System (ADS)

    Hung, Chen-Lung

    2016-05-01

    Interfacing light with cold atoms localized near photonic crystal cavities and waveguides presents new opportunities for realizing scalable quantum networks and novel quantum phases of light and matter. Such hybrid system could bring together excellent mobility of photons, and quantum non-linearity as well as control toolbox available for cold atoms in a highly engineered setting. In this talk, I will discuss recent experimental progress toward achieving strong atom-atom interactions in a nanophotonic lattice for light, and theory prospects for inducing long-range quantum dynamics for quantum network and many-body physics.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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…

  4. 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.

  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. 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)

  7. ATOMIC AND MOLECULAR PHYSICS: Tunneling between double wells of atom in crossed electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Shen, Li; Wang, Lei; Yang, Hai-Feng; Liu, Xiao-Jun; Liu, Hong-Ping

    2009-12-01

    The tunneling between double wells of atom in crossed electromagnetic fields is investigated by a one-dimensional Hamiltonian model. The crossed fields induced outer well is apart from the nuclear origin and it is very difficult to access by means of spectroscopy but it will be possible if there exists the tunneling of the electron between the outer well and the Coulomb potential predominated well at the nuclear origin. A one-dimensional quantum calculation with B-spline basis has been performed for hydrogen atom in crossed fields accessible in our laboratory, at B = 0.8 T and F = -220 V·cm-1. The calculation shows that the wavefunctions of some excited states close to the Stark saddle point in the outer well extend over to the Coulomb potential well, making it possible to penetrate the quantum information of the outer well. However, the tunneling rate is very small and the spectral measurement of the transitions from the ground state should be of a high resolution and high sensitivity.

  8. 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.

  9. Quantum Zeno effect and quantum Zeno paradox in atomic physics

    NASA Astrophysics Data System (ADS)

    Block, Ellen; Berman, P. R.

    1991-08-01

    Itano and co-workers [Wayne M. Itano, D. J. Heinzen, J. J. Bollinger, and D. J. Wineland, Phys. Rev. A 41, 2295 (1990)] have recently reported the experimental verification of the quantum Zeno effect, which is the inhibition of a quantum transition by frequent measurements. In this article, we offer an alternative interpretation of the quantum Zeno effect. We show that an analysis of the dynamics of the full three-level system gives the same result. There is no need to assume explicitly that the wave function has collapsed, nor even to assume that an ideal measurement has been made. In addition, we differentiate between what has been referred to as the quantum Zeno effect and what has been termed the quantum Zeno paradox. The former is the inhibition of induced transitions, and the latter is the, as yet experimentally unobserved, inhibition of spontaneous decay. Our interpretation, which emphasizes the ``measurement''-induced interruption of atomic-state coherences as the cause of inhibited quantum transitions, suggests a resolution to the quantum Zeno paradox. The theoretical limit of continuous observation is discussed.

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

    SciTech Connect

    LeBrun, T.

    1996-12-31

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

  11. Physically Measuring Thickness of Thin Films via Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Acosta, Guillermo; Allred, D.; Davis, R.; Webb, Nick

    2002-03-01

    In our research of thin films, we invest a great deal of time and energy in characterizing our films physical and optical properties. We have found that it is imperative to have the ability to determine, with confidence, the thickness of our films when we try to describe a materials optical performance, especially true for work in the extreme ultraviolet. Unfortunately, weve learned this is not as simple a task as it would seem. Methods that are optical in nature that determine how thick a film is are less effective for very thin films (typically our films are 25-150 A thick). We would much rather be able to use an AFM to physically measure a films thickness. After much trial and tribulation, we are happy to report the method we have developed. Our technique involves using a rigidly supported, stainless steel razor blade to mask the substrate during deposition, leaving a distinct, abrupt edge when removed. The device is named the Abruptor.

  12. 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.

  13. 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).

  14. 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.

  15. ATOMIC AND MOLECULAR PHYSICS: Ionization of atoms by chirped attosecond pulses

    NASA Astrophysics Data System (ADS)

    Tan, Fang; Peng, Liang-You; Gong, Qi-Huang

    2009-11-01

    We investigate the ionization dynamics of atoms by chirped attosecond pulses using the strong field approximation method. The pulse parameters are carefully chosen in the regime where the strong field approximation method is valid. We analyse the effects of the chirp of attosecond pulses on the energy distributions and the corresponding left-right asymmetry of the ionized electrons. For a single chirped attosecond pulse, the ionized electrons can be redistributed and the left-right asymmetry shows oscillations because of the introduction of the chirp. For time-delayed double attosecond pulses at different intensities with the weaker one chirped, exchanging the order of the two pulses shows a relative shift of the energy spectra, which can be explained by the different effective time delays of different frequency components because of the chirp.

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

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

    SciTech Connect

    Not Available

    1987-01-01

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

  18. HISTRAP (Heavy Ion Storage Ring for Atomic Physics) prototype hardware studies

    SciTech Connect

    Olsen, D.K.; Atkins, W.H.; Dowling, D.T.; Johnson, J.W.; Lord, R.S.; McConnell, J.W.; Milner, W.T.; Mosko, S.W.; Tatum, B.A.

    1989-01-01

    HISTRAP, Heavy Ion Storage Ring for Atomic Physics, is a proposed 2.67-Tm synchrotron/cooler/storage ring optimized for advanced atomic physics research which will be injected with ions from either the HHIRF 25-MV tandem accelerator or a dedicated ECR source and RFQ linac. Over the last two years, hardware prototypes have been developed for difficult and long lead-time components. A vacuum test stand, the rf cavity, and a prototype dipole magnet have been designed, constructed, and tested. 7 refs., 8 figs., 2 tabs.

  19. 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.

  20. Source formulation for fluid turbulence simulations from atomic physics differential cross sections

    NASA Astrophysics Data System (ADS)

    Muller, S. H.; Holland, C.; Tynan, G. R.; Xu, M.; Yu, J. H.

    2009-11-01

    The derivation of the correct functional form of source terms in plasma fluid theory is revisited. The relation between the fluid source terms and atomic physics differential cross sections is established for particle-impact ionization. It is shown that the interface between atomic and plasma physics is completely described by three scalar functions of the incident particle energy, which are properties of the differential cross sections only. For electron-impact ionization, the BEB and BED models [Y.-K. Kim and M. E. Rudd, Phys. Rev. A, 50 (1994) 3954] are used to calculate these functions analytically, yielding expressions that both accurately capture the physics and can be efficiently evaluated within fluid simulation codes. The source terms explain the observed electron temperature regimes in a wide variety of basic plasma physics experiments, including the trends across different gases.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

  3. DETECTORS FOR ACCELERATOR-BASED NUCLEAR SECURITY APPLICATIONS

    SciTech Connect

    Warren, Glen A.; Stave, Sean C.; Miller, Erin A.

    2015-08-31

    We present of review of detector systems used in accelerator-based national security applications. In gen-eral, the detectors used for these applications are also used in passive measurements. The critical difference is that detector systems for accelerator-based applications in general need to discriminate beam-generated background from the intended signal. Typical techniques to remove background include shielding, timing, selection of sensitive materials, and choice of accelerator.

  4. 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…

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  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. 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.

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

    PubMed

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

    2014-04-24

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

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Goncharov, German A.; Ryabev, Lev D.

    2001-01-01

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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    PubMed Central

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

    2016-01-01

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

  2. Kinetic theory and atomic physics corrections for determination of ion velocities from charge-exchange spectroscopy

    NASA Astrophysics Data System (ADS)

    Muñoz Burgos, J. M.; Burrell, K. H.; Solomon, W. M.; Grierson, B. A.; Loch, S. D.; Ballance, C. P.; Chrystal, C.

    2013-09-01

    Charge-exchange spectroscopy is a powerful diagnostic tool for determining ion temperatures, densities and rotational velocities in tokamak plasmas. This technique depends on detailed understanding of the atomic physics processes that affect the measured apparent velocities with respect to the true ion rotational velocities. These atomic effects are mainly due to energy dependence of the charge-exchange cross-sections, and in the case of poloidal velocities, due to gyro-motion of the ion during the finite lifetime of the excited states. Accurate lifetimes are necessary for correct interpretation of measured poloidal velocities, specially for high density plasma regimes on machines such as ITER, where l-mixing effects must be taken into account. In this work, a full nl-resolved atomic collisional radiative model coupled with a full kinetic calculation that includes the effects of electric and magnetic fields on the ion gyro-motion is presented for the first time. The model directly calculates from atomic physics first principles the excited state lifetimes that are necessary to evaluate the gyro-orbit effects. It is shown that even for low density plasmas where l-mixing effects are unimportant and coronal conditions can be assumed, the nl-resolved model is necessary for an accurate description of the gyro-motion effects to determine poloidal velocities. This solution shows good agreement when compared to three QH-mode shots on DIII-D, which contain a wide range of toroidal velocities and high ion temperatures where greater atomic corrections are needed. The velocities obtained from the model are compared to experimental velocities determined from co- and counter-injection of neutral beams on DIII-D.

  3. 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

  4. 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.

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

    DOE PAGES

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

    2016-08-12

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

  6. 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)

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Taber, Keith S.

    2013-08-01

    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 how they understood the forces acting within the two systems. A sample of just over 100 across the 15-18 age range responded to a pencil-and-paper instrument that asked about four aspects of the two systems. It was found that for both systems, about four fifths of students expected forces to decrease with increasing distance; but that only a little over half expected there to be interactions between the minor constituents (electrons and planets). Most students failed to apply Newton's third law to either system. There was a considerable difference in the extent to which respondents were able to identify the type of force acting in the systems (nearly all for the solar system, but only a small proportion in the case of the atom). The findings are considered in terms of both the limitations of students' understanding of the basic physics and possible implications for the use of the teaching analogy.

  9. 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.

  10. Simulating and exploring Weyl semimetal physics with cold atoms in a two-dimensional optical lattice

    NASA Astrophysics Data System (ADS)

    Zhang, Dan-Wei; Zhu, Shi-Liang; Wang, Z. D.

    2015-07-01

    We propose a scheme to simulate and explore Weyl semimetal physics with ultracold fermionic atoms in a two-dimensional square optical lattice subjected to experimentally realizable spin-orbit coupling and an artificial dimension from an external parameter space, which may increase experimental feasibility compared with the cases in three-dimensional optical lattices. It is shown that this system with a tight-binding model is able to describe essentially three-dimensional Weyl semimetals with tunable Weyl points. The relevant topological properties are also addressed by means of the Chern number and the gapless edge states. Furthermore, we illustrate that the mimicked Weyl points can be experimentally detected by measuring the atomic transfer fractions in a Bloch-Zener oscillation, and the characteristic topological invariant can be measured with the particle pumping approach.

  11. 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.

  12. 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.

  13. ATOMIC AND MOLECULAR PHYSICS: Spontaneous Emission of a Polarized Atom in a Medium Between Two Parallel Mirrors

    NASA Astrophysics Data System (ADS)

    Wang, De-Hua; Huang, Kai-Yun; Xu, Qiang

    2010-01-01

    Using the photon closed orbit theory, the spontaneous emission rate of a polarized atom in a medium between two parallel mirrors is derived and calculated. It is found that the spontaneous emission rate of a polarized atom between the mirrors is related to the atomic position and the polarization direction. The results show that in the vicinity of the mirror, the variation of the spontaneous emission rate depends crucially on the atomic polarization direction. With the increase of the polarization angle, the oscillation in the spontaneous emission rate becomes decreased. For the polarization direction parallel to the mirror plane, the oscillation is the greatest; while for the perpendicular polarization direction, the oscillation is nearly vanished. The agreement between our result and the quantum electrodynamics result suggests the correctness of our calculation. This study further verifies that the atomic spontaneous emission process can be effectively controlled by changing the polarization orientation of the atom.

  14. 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…

  15. 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…

  16. Design of a beam shaping assembly and preliminary modelling of a treatment room for accelerator-based BNCT at CNEA.

    PubMed

    Burlon, A A; Girola, S; Valda, A A; Minsky, D M; Kreiner, A J; Sánchez, G

    2011-12-01

    This work reports on the characterisation of a neutron beam shaping assembly (BSA) prototype and on the preliminary modelling of a treatment room for BNCT within the framework of a research programme for the development and construction of an accelerator-based BNCT irradiation facility in Buenos Aires, Argentina. The BSA prototype constructed has been characterised by means of MCNP simulations as well as a set of experimental measurements performed at the Tandar accelerator at the National Atomic Energy Commission of Argentina.

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. ATOMIC AND MOLECULAR PHYSICS: Interference effects on the photoionization cross sections between two neighbouring atoms: nitrogen as an example

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Hua; Yuan, Jian-Min

    2009-12-01

    Interference effects on the photoionization cross sections between two neighbouring atoms are considered based on the coherent scattering of the ionized electrons by the two nuclei when their separation is less than or comparable to the de Broglie wave length of the ionized electrons. As an example, the single atomic nitrogen ionization cross section and the total cross sections of two nitrogen atoms with coherently added photoionization amplitudes are calculated from the threshold to about 60 Å (1 Å = 0.1 nm) of the photon energy. The photoionization cross sections of atomic nitrogen are obtained by using the close-coupling R-matrix method. In the calculation 19 states are included. The ionization energy of the atomic nitrogen and the photoionization cross sections agree well with the experimental results. Based on the R-matrix results of atomic nitrogen, the interference effects between two neighbouring nitrogen atoms are obtained. It is shown that the interference effects are considerable when electrons are ionized just above the threshold, even for the separations between the two atoms are larger than two times of the bond length of N2 molecules. Therefore, in hot and dense samples, effects caused by the coherent interference between the neighbours are expected to be observable for the total photoionization cross sections.

  2. 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.

  3. ATOMIC AND MOLECULAR PHYSICS: Multiphoton ionization of the hydrogen atom exposed to circularly or linearly polarized laser pulses

    NASA Astrophysics Data System (ADS)

    Wang, Pei-Jie; He, Feng

    2009-12-01

    This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent Schrödinger equation. It finds that the ratio of the ionization probabilities by linearly and circularly polarized laser pulses varies with the numbers of absorbing photons. With the same laser intensity, the circularly polarized laser pulse favors to ionize the atom with more ease than the linearly polarized laser pulse if only two or three photons are necessary to be absorbed. For the higher order multiphoton ionization, the linearly polarized laser pulse has the advantage over circularly polarized laser pulse to ionize the atom.

  4. ATOMIC AND MOLECULAR PHYSICS: Scaled-energy spectroscopy of a |M| = 1 Rydberg barium atom in an electric field

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Quan, Wei; Shen, Li; Yang, Hai-Feng; Shi, Ting-Yun; Liu, Xiao-Jun; Liu, Hong-Ping; Zhan, Ming-Sheng

    2009-11-01

    We observe strong energy-dependent quantum defects in the scaled-energy Stark spectra for |M| = 1 Rydberg states of barium atoms at three scaled energies: ɛ = -2.000, ɛ = -2.500 and ɛ = -3.000. In an attempt to explain the observations, theoretical calculations of closed orbit theory based on a model potential including core effect are performed for non-hydrogenic atoms. While such a potential has been uniformly successful for alkali atoms with a single valence electron, it fails to match experimental results for barium atoms in the 6snp Rydberg states with two valence electrons. Our study points out that this discrepancy is due to the strong perturbation from the 5d8p state, which voids the simple approximation for constant quantum defects of principle quantum number n.

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

    NASA Astrophysics Data System (ADS)

    Nori, Franco

    2012-02-01

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

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

    PubMed Central

    Kempe, André; Lackner, Maximilian

    2016-01-01

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

  7. ATOMIC AND MOLECULAR PHYSICS: Model Potential Calculations of Oscillator Strength Spectra of Rydberg Li Atoms in External Fields

    NASA Astrophysics Data System (ADS)

    Meng, Hui-Yan; Shi, Ting-Yun

    2009-08-01

    By combining the B-spline basis set with model potential (B-spline + MP), we present oscillator strength spectra of Rydberg Li atoms in external fields. The photoabsorption spectra are analyzed. Over the narrow energy ranges considered in this paper, the structure of the spectra can be independent of the initial state chosen for a given atom. Our results are in good agreement with previous high-precision experimental data and theoretical calculations, where the R-matrix approach together with multichannel quantum defect theory (R-matrix+MQDT) was used. It is suggested that the present methods can be applied to deal with the oscillator strength spectra of Rydberg atoms in crossed electric and magnetic fields.

  8. 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.

  9. Overview of the IBA accelerator-based BNCT system.

    PubMed

    Forton, E; Stichelbaut, F; Cambriani, A; Kleeven, W; Ahlback, J; Jongen, Y

    2009-07-01

    During the last few years, IBA started the development of an accelerator-based BNCT system. The accelerator is a Dynamitron built by RDI in USA and will produce a 20 mA proton beam at 2.8 MeV. Neutrons will be produced by the (7)Li(p,n)(7)Be nuclear reaction using a thin lithium target. The neutron energy spectrum will be tailored using a beam shaping assembly. This overview presents the current status of the system: after a description of every component, some design issues, solutions and experimental tests will be discussed.

  10. Physical properties of native bacterial biofilm cells measured by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Aidala, Katherine; Volle, Catherine; Ferguson, Megan; Spain, Eileen; Nunez, Megan

    2010-03-01

    Atomic force microscopy offers a way to probe physical properties of bacteria that are adhered to a surface. We study early stage biofilms that natively adhere to a glass surface, without artificial fixation methods. We present images and force curves from five different bacteria, consisting of two gram positive and three gram negative strains, as well as both smooth and rough gram negative strains. The linear portion of the approach curve reveals the gram positive strains are stiffer than the gram negative strains. The non-linear portion of the approach curve, determined by the initial interaction between the tip and cell, differentiates the smooth and rough strains. Fixation of free-swimming planktonic cells by NHS and EDC dramatically changed the measured properties. These results can be understood from the structure of the cells.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. ATOMIC AND MOLECULAR PHYSICS: Experimental study of highly excited even-parity bound states of the Sm atom

    NASA Astrophysics Data System (ADS)

    Qin, Wen-Jie; Dai, Chang-Jian; Xiao, Ying; Zhao, Hong-Ying

    2009-08-01

    In this work, a three-step autoionization detection method and direct photoionization detection method are employed to measure the highly excited even-parity states of the Sm atom in the energy region between 36360 cm-1 and 40800 cm-1. Comparisons between the results from the two detection techniques enable us to discriminate the Rydberg states from the valence states in the same energy region with the information of level energies, possible J values and their relative intensities. Furthermore, in the experiment two different excitation schemes are designed to obtain the spectra of highly excited even-parity states of the Sm atom. With a detailed analysis of the experimental data, this work not only confirms the results about many spectral data from the literature with different excitation schemes, but also reports new spectral data on 29 Rydberg states and 23 valence states.

  18. ATOMIC AND MOLECULAR PHYSICS: Influence of Isotope Substitution Helium Atom on Partial Cross Sections in He-HF Collisions

    NASA Astrophysics Data System (ADS)

    Yu, Chun-Ri; Zhang, Jie; Chen, Li; Jiang, Gui-Sheng; Huang, Guo-Dong

    2009-11-01

    Close-coupling equation and anisotropic potential developed in our previous research are applied to HF-3He (4He, 6He, 8He, 10He) collision system, and partial cross sections (PCSs) at the incident energy of 40 meV are calculated. By analyzing the differences of these PCSs, change rules of PCSs with the increase of partial wave number, and with the change of the mass of isotope substitution helium atom are obtained. The results show that excitation PCSs converge faster than elastic PCSs for collision energy and each of systems considered here. Also excitation PCSs converge more rapidly for high-excited states. Tail effect is present only in elastic scattering and low-excited states but not in high-excited states. With the increase of the mass of isotope substitution helium atom, converging speed of elastic, total inelastic, and state-to-state excitation PCS slows down, and the maxima of these PCSs undergoes a regular change.

  19. ATOMIC AND MOLECULAR PHYSICS: Simulation of Chromium Atom Deposition Pattern in a Gaussain Laser Standing Wave with Different Laser Power

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Tao; Zhu, Bao-Hua

    2009-07-01

    One-dimensional deposition of a neutral chromium atomic beam focused by a near-resonant Gaussian standing-laser field is discussed by using a fourth-order Runge-Kutta type algorithm. The deposition pattern of neutral chromium atoms in a laser standing wave with different laser power is discussed and the simulation result shows that the full width at half maximum (FWHM) of a nanometer stripe is 115 nm and the contrast is 2.5:1 with laser power 3.93 mW; the FWHM is 0.8 nm and the contrast is 27:1 with laser power 16 mW, the optimal laser power; but with laser power increasing to 50 mW, the nanometer structure forms multi-crests and the quality worsens quickly with increasing laser power.

  20. ATOMIC AND MOLECULAR PHYSICS: Calculation of Energy and Other Properties of Muonic Helium Atom Using Boundary Conditions of Wave Function

    NASA Astrophysics Data System (ADS)

    Rezaei, B.

    2010-09-01

    The properties of muonic helium atom (4He+2μ-e-) in ground state are considered. In this work, the energy and average distance between particles have been obtained using a wave function, which satisfies boundary conditions. It is shown that the obtained energy are very close to the values calculated by others. But the small differences of the expectation values of r2n are due to the incorporated boundary conditions in proposed wave function and are expected.

  1. Improving the physical realism and structural accuracy of protein models by a two-step atomic-level energy minimization.

    PubMed

    Xu, Dong; Zhang, Yang

    2011-11-16

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

  2. 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.

  3. 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.

  4. Current Status of the IAP NASU Accelerator-Based Analytical Facility

    NASA Astrophysics Data System (ADS)

    Buhay, O. M.; Drozdenko, A. A.; Zakharets, M. I.; Ignat'ev, I. G.; Kramchenkov, A. B.; Miroshnichenko, V. I.; Ponomarev, A. G.; Storizhko, V. E.

    Accelerator-based analytical facility (AAF) of the Institute of Applied Physics of the National Academy of Sciences of Ukraine is described. The research facility is based on a compact single ended machine with the maximum accelerating potential of 2 MV. The facility has five analytical end-stations: an scanning ion microprobe end-station with spatial resolution of less than 2 μm, a high-resolution Rutherford backscattering spectrometry end-station with a magnetic spectrometer (ΔE/E<1.5×10-3), end-station for elastic recoil detection analysis equipped with an electrostatic spectrometer (ΔE/E<1.5×10-3), end-station for particle induced gamma ray spectroscopy, and an ion induced luminescence end-station. Key specifications of the end-stations and their potential features are given.

  5. 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

  6. 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

  7. ATOMIC AND MOLECULAR PHYSICS: High Accuracy Calculation for Excited-State Energies of H Atoms in a Magnetic Field

    NASA Astrophysics Data System (ADS)

    Zhao, Li-Bo; Du, Meng-Li

    2009-08-01

    Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2s0, 3d'0, 3p0, 3p-1, 3d-1, 4d-1, 3d-2, 4d-2, 4f-2, and 5f-2 as a function of magnetic field strengths with a range from zero up to 2.35 × 106 T. The obtained results are compared with available high accuracy theoretical data reported in the literature and found to be in excellent agreement. The comparison also shows that the current method can produce energy levels with an accuracy higher than the existing high accuracy method [Phys. Rev. A 54 (1996) 287]. Here high accuracy energy levels are for the first time reported for the 3d'0, 4d-1, 4d-2, 4f-2, and 5f-2 states.

  8. 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.

  9. ATOMIC AND MOLECULAR PHYSICS: Elastic Collisions Between two Ground-State P and D Atoms at Low and Ultralow Temperatures

    NASA Astrophysics Data System (ADS)

    Shi, De-Heng; Zhang, Jin-Ping; Sun, Jin-Feng; Ma, Heng; Liu, Yu-Fang; Zhu, Zun-Lue

    2010-02-01

    The PD(X3Σ-) interaction potential is constructed using the CCSD(T) theory and the basis set, aug-cc-pV5Z. Using this potential, the spectroscopic parameters are accurately determined. The present Do, De, Re, ωe, ωeχe, αe, and Be are of 3.056 99 eV, 3.161 75 eV, 0.142 39 nm, 1701.558 cm-1, 23.6583 cm-1, 0.085 99 cm-1, and 4.3963 cm-1, respectively, which almost perfectly conform with the measurements. A total of 26 vibrational states is predicted when J = 0 by solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which favorably agree with the experiments. The total and various partial-wave cross sections are calculated for the elastic impact between two ground-state P and D atoms at 1.0 × 10-12 - 1.0 × 10-4 a.u. when they approach each other along the PD(X3Σ-) potential. No shape resonances exist in the total elastic cross sections, though the peaks can be found for each partial wave until l = 6. The shape of the total elastic cross sections is dominated by the s partial wave at very low temperatures. Due to the weakness of the shape resonances of each partial wave, they are all passed into oblivion by the strong total elastic cross sections.

  10. 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.

  11. 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…

  12. 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…

  13. Emulating Solid-State Physics with a Hybrid System of Ultracold Ions and Atoms

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  14. Emulating Solid-State Physics with a Hybrid System of Ultracold Ions and Atoms

    NASA Astrophysics Data System (ADS)

    Hofstetter, Walter; Ulf, Bissbort; Cocks, Daniel; Negretti, Antonio; Idziaszek, Zbigniew; Calarco, Tommaso; Schmidt-Kaler, Ferdinand; Gerritsma, Rene

    2014-05-01

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

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

    PubMed

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

    2013-08-23

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

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

    PubMed

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

    2013-08-23

    We propose and theoretically investigate a hybrid system composed of a crystal of trapped ions coupled to a cloud of ultracold fermions. The ions form a periodic lattice and induce a band structure in the atoms. This system combines the advantages of high fidelity operations and detection offered by trapped ion systems with ultracold atomic systems. It also features close analogies to natural solid-state systems, as the atomic degrees of freedom couple to phonons of the ion lattice, thereby emulating a solid-state system. Starting from the microscopic many-body Hamiltonian, we derive the low energy Hamiltonian, including the atomic band structure, and give an expression for the atom-phonon coupling. We discuss possible experimental implementations such as a Peierls-like transition into a period-doubled dimerized state. PMID:24010420

  17. ATOMIC AND MOLECULAR PHYSICS: An alternative view of condensed-phase photoionization

    NASA Astrophysics Data System (ADS)

    Ma, Xiao-Guang; Yang, Chuan-Lu; Gong, Yu-Bing; Wang, Mei-Shan

    2009-12-01

    This paper proposes an accurate valuable interpretation scheme to study the evolvement of the photoionization processes from the isolated to the condensed atoms by a unique ab initio method. The variations of the photoionization cross sections of the atomic sodium with the photoelectron energy and the boundary radius of the atomic configuration space are studied in this new scheme by the R-matrix method. The discrepancy in the photoionization spectra of the isolated and the condensed sodium has been explained quantitatively and understood successfully by this alternative view in detail for the first time.

  18. 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)

  19. 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.

  20. 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.

  1. 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.

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

    SciTech Connect

    Karshenboim, S. G.

    2010-10-01

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

  3. 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.

  4. The Basic Physics of Electron-Atom Collisions: How Much Do We Know and How Much Is Left to Learn?

    NASA Astrophysics Data System (ADS)

    Gay, T. J.

    2001-05-01

    Electron-atom scattering is perhaps the most investigated quantum mechanical process in physics, but not the best understood. Indeed, the simplest example of this process, electron-hydrogen scattering, has only just recently succumbed to comprehensive solution. Given that we believe in Quantum Mechanics, Special Relativity, and Coulomb's Law, what makes electron-atom scattering so difficult to understand? This talk will present a review of where we stand, both theoretically and experimentally, in our knowledge of these collisions ranging from total cross sections to the most esoteric spin and polarization parameters. Particular attention will be paid to areas where lack of basic knowledge limits our understanding of applied electron-driven processes. Recommendations for future experiments will be made.

  5. 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.

  6. 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.

  7. 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…

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

    SciTech Connect

    Karshenboim, S. G.

    2010-06-04

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

  9. ATOMIC AND MOLECULAR PHYSICS: Static dipole polarizabilities of Scn (n <= 15) clusters

    NASA Astrophysics Data System (ADS)

    Li, Xi-Bo; Wang, Hong-Yan; Luo, Jiang-Shan; Guo, Yun-Dong; Wu, Wei-Dong; Tang, Yong-Jian

    2009-08-01

    The static dipole polarizabilities of scandium clusters with up to 15 atoms are determined by using the numerically finite field method in the framework of density functional theory. The electronic effects on the polarizabilities are investigated for the scandium clusters. We examine a large highest occupied molecular orbital — the lowest occupied molecular orbital (HOMO-LUMO) gap of a scandium cluster usually corresponds to a large dipole moment. The static polarizability per atom decreases slowly and exhibits local minimum with increasing cluster size. The polarizability anisotropy and the ratio of mean static polarizability to the HOMO-LUMO gap can also reflect the cluster stability. The polarizability of the scandium cluster is partially related to the HOMO-LUMO gap and is also dependent on geometrical characteristics. A strong correlation between the polarizability and ionization energy is observed.

  10. ATOMIC AND MOLECULAR PHYSICS: Structures and Electronic Properties of CuN (N <= 13) Clusters

    NASA Astrophysics Data System (ADS)

    Feng, Cui-Ju; Zhang, Xiao-Yan

    2009-10-01

    A systematic study on the structures and electronic properties of copper clusters has been performed using the density functional theory. In the calculation, there are many isomers near the ground state for small copper clusters. Our results show that the three-dimensional isomers of copper clusters start from Cu7 cluster and then show a tendency to form more compact structures. The results of the formation energy and the second derivative of binding energy with cluster size show that besides N = 8, N = 11 is also a magic number. Furthermore, it is the first time to find that the ground state of 11-atom clusters is a biplanar structure as same as the 13-atom cluster. The clear odd-even alternation as cluster size for the formation energy indicates the stability of electronic close shell existed in the range studied.

  11. 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

  12. 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.

  13. Whispering gallery states of neutrons and anti-hydrogen atoms and their applications to fundamental and surface physics

    NASA Astrophysics Data System (ADS)

    Nesvizhevsky, Valery

    2013-03-01

    The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It is intensively used and explored due to its numerous crucial applications. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for neutrons and (anti)atoms. For (anti)matter waves, it includes a new feature: a massive particle is settled in quantum states, with parameters depending on its mass. In this talk, we present the first observation of the quantum whispering-gallery effect for matter particles (cold neutrons) 1-2. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to recently discovered gravitational quantum states of neutrons3. These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a quantum state. Deeply bound long-living states are weakly sensitive to surface potential; highly excited short-living states are very sensitive to the wall nuclear potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects. Analogous phenomena could be measured with atoms and anti-atoms 4-5.

  14. 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…

  15. 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.

  16. Heavy Ion Storage Ring for Atomic Physics (HISTRAP) vacuum test stand for pressures of 10/sup -12/ Torr

    SciTech Connect

    Johnson, J.W.; Atkins, W.H.; Dowling, D.T.; McConnell, J.W.; Milner, W.T.; Olsen, D.K.

    1989-05-01

    HISTRAP (Heavy Ion Storage Ring for Atomic Physics) is a proposed synchrotron/cooler/storage ring accelerator optimized for advanced atomic physics research. The ring has a circumference of 46.8 m, a bore diameter of /similar to/15 cm, and requires a vacuum of 10/sup -12/ Torr to decelerate highly charged, very heavy ions down to low energies. To be able to test components and procedures to achieve this pressure, a test stand approximately modeling 1/16 of the ring vacuum chamber has been built. The 3.5-m-long test stand has been fabricated from 10-cm-diam components, with 316LN stainless-steel flanges. Prior to assembly, these components were vacuum fired at 950 /sup 0/C at a pressure of 10/sup -4/ Torr. The test stand is bakable in situ at 300 /sup 0/C. Pumping is achieved with two 750 l/s titanium sublimator pumps and one 60 l/s ion pump. Pressure is measured with two extractor ion gauges and a 10/sup -4/ partial pressure residual gas analyser. The roughing for the test stand consists of cryosorption pumps followed by a cryopump. A pressure of 4 x 10/sup -12/ Torr has been achieved.

  17. HISTRAP (Heavy Ion Storage Ring for Atomic Physics) vacuum test stand for pressures of 10/sup -12/ Torr

    SciTech Connect

    Johnson, J.W.; Atkins, W.H.; Dowling, D.T.; McConnell, J.W.; Milner, W.T.; Olsen, D.K.

    1988-01-01

    HISTRAP, Heavy Ion Storage Ring for Atomic Physics, is a proposed synchrotron/cooler/storage ring accelerator optimized for advanced atomic physics research. The ring has a circumference of 46.8 m, a bore diameter of about 15 cm, and requires a vacuum of 10/sup -12/ Torr in order to decelerate highly-charged very-heavy ions down to low energies. To be able to test components and procedures to achieve this pressure, a test stand approximately modeling one-sixteenth of the ring vacuum chamber has been built. The 3.5-m-long test stand has been fabricated from 10-cm-diameter components, with 316LN stainless steel flanges. Prior to assembly, these components were vacuum fired at 950/degree/C at a pressure of 10/sup -4/ Torr. The test stand is bakeable in situ at 300/degree/C. Pumping is achieved with two 750-L/s titanium sublimator pumps and one 60-L/s ion pump. Pressure is measured with two extractor ion gauges and a 10/sup -14/ PP RGA. The roughing for the test stand consists of cryosorption pumps followed by a cryopump. A pressure of 4 x 10/sup -12/ Torr has been achieved. 7 refs., 5 figs.

  18. 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.

  19. Exploring mesoscopic physics of vacancy-ordered systems through atomic scale observations of topological defects.

    PubMed

    Borisevich, A Y; Morozovska, A N; Kim, Young-Min; Leonard, D; Oxley, M P; Biegalski, M D; Eliseev, E A; Kalinin, S V

    2012-08-10

    Vacancy-ordered transition metal oxides have multiple similarities to classical ferroic systems including ferroelectrics and ferroelastics. The expansion coefficients for corresponding Ginzburg-Landau-type free energies are readily accessible from bulk phase diagrams. Here, we demonstrate that the gradient and interfacial terms can quantitatively be determined from the atomically resolved scanning transmission electron microscopy data of the topological defects and interfaces in model lanthanum-strontium cobaltite. With this knowledge, the interplay between ordering, chemical composition, and mechanical effects at domain walls, interfaces and structural defects can be analyzed.

  20. On the choice of the electron-electron potential in relativistic atomic physics

    NASA Technical Reports Server (NTRS)

    Sucher, J.

    1988-01-01

    In the calculation of relativistic effects in the structure of many-electron atoms there are two popular choice for the operator V used to represent the electron-electron interaction. One of these, V(I), is associated with the use of the Coulomb gauge propagator for photons; the other, V(II), is associated with the use of the Feynman gauge propagator. In contrast to V(I), the nonperturbative use of V(II) leads to energy levels which are already incorrect in order (alpha exp 4)m. This fact provides a quantitative argument for preferring V(I) to V(II).

  1. ATOMIC AND MOLECULAR PHYSICS: Energy spectrum and superfluidity of spin-2 ultracold bosons in optical lattices

    NASA Astrophysics Data System (ADS)

    Wang, Yong-Jun; Liu, Xian-Feng; Han, Jiu-Rong

    2009-12-01

    This paper studies the superfluidity of ultracold spin-2 Bose atoms with weak interactions in optical lattices by calculating the excitation energy spectrum using the Bogoliubov approach. The energy spectra exhibit the characteristics of the superfluid-phase explicitly and it finds the nonvanishing critical speeds of superfluid. The obtained results display that the critical speeds of superfluid are different for five spin components and can be controlled by adjusting the lattice parameters in experiments. Finally it discusses the feasibilities of implementing and measuring superfluid.

  2. Mott physics and collective modes: An atomic approximation of the four-particle irreducible functional

    NASA Astrophysics Data System (ADS)

    Ayral, Thomas; Parcollet, Olivier

    2016-08-01

    We discuss a generalization of the dynamical mean field theory (DMFT) for strongly correlated systems close to a Mott transition based on a systematic approximation of the fully irreducible four-point vertex. It is an atomic-limit approximation of a functional of the one- and two-particle Green functions, built with the second Legendre transform of the free energy with respect to the two-particle Green function. This functional is represented diagrammatically by four-particle irreducible (4PI) diagrams. Like the dynamical vertex approximation (D Γ A ), the fully irreducible vertex is computed from a quantum impurity model whose bath is self-consistently determined by solving the parquet equations. However, in contrast with D Γ A and DMFT, the interaction term of the impurity model is also self-consistently determined. The method interpolates between the parquet approximation at weak coupling and the atomic limit, where it is exact. It is applicable to systems with short-range and long-range interactions.

  3. Effective-field-theory analysis of Efimov physics in heteronuclear mixtures of ultracold atomic gases

    NASA Astrophysics Data System (ADS)

    Acharya, Bijaya; Ji, Chen; Platter, Lucas

    2016-09-01

    We use an effective-field-theory framework to analyze the Efimov effect in heteronuclear three-body systems consisting of two species of atoms with a large interspecies scattering length. In the leading-order description of this theory, various three-body observables in heteronuclear mixtures can be universally parametrized by one three-body parameter. We present the next-to-leading corrections, which include the effects of the finite interspecies effective range and the finite intraspecies scattering length, to various three-body observables. We show that only one additional three-body parameter is required to render the theory predictive at this order. By including the effective range and intraspecies scattering length corrections, we derive a set of universal relations that connect the different Efimov features near the interspecies Feshbach resonance. Furthermore, we show that these relations can be interpreted in terms of the running of the three-body counterterms that naturally emerge from proper renormalization. Finally, we make predictions for recombination observables of a number of atomic systems that are of experimental interest.

  4. Size-controlled bismuth nanoparticles physically grown by the support of cobalt atomic flux

    NASA Astrophysics Data System (ADS)

    Lee, Ho Seok; Noh, Jin-Seo

    2016-04-01

    Bi nanoparticle arrays with the almost monodispersity were synthesized using a magnetically assisted physical method. The average size and the overall morphology of Bi nanoparticles could be controlled by the adjustment of several parameters such as relative powers applied to Bi and Co targets, substrate temperature, and growth time. It was disclosed that Bi nanoparticles grow larger at a higher relative power to Bi, higher substrate temperature, and longer growth time, accompanying the deterioration of well-developed faceted structures. This physical method may provide a facile and fast route to achieving quality Bi nanoparticle arrays with a certain extent of size and morphology controllability.

  5. 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.

  6. 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…

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

    NASA Astrophysics Data System (ADS)

    Hulet, Randall

    2016-05-01

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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Pantelides, Sokrates T.

    2003-03-01

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

  11. ATOMIC AND MOLECULAR PHYSICS: First Principles Simulation of Molecular Oxygen Adsorption on SiC Nanotubes

    NASA Astrophysics Data System (ADS)

    Ganji, M. D.; Ahaz, B.

    2010-04-01

    We study the binding of molecular oxygen to a (5, 0) single walled SiC nanotube, by means of density functional calculations. The center of a hexagon of silicon and carbon atoms in sites on SiCNT surfaces is the most stable adsorption site for O2 molecule, with a binding energy of -38.22 eV and an average Si-O binding distance of 1.698 Å. We have also tested the stability of the O2-adsorbed SiCNT/CNT with ab initio molecular dynamics simulation which have been carried out at room temperature. Furthermore, the adsorption of O2 on the single walled carbon nanotubes has been investigated. Our first-principles calculations predict that the O2 adsorptive capability of silicon carbide nanotubes is much better than that of carbon nanotubes. This might have potential for gas detection and energy storage.

  12. 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.

  13. 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.

  14. 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.

  15. ATOMIC AND MOLECULAR PHYSICS: Jet-like structures in photoelectron angular distributions

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Zhang, Jing-Tao; Ren, Xiang-He; Xu, Zhi-Zhan

    2009-11-01

    The photoelectron angular distributions (PADs) of hydrogen atoms in an intense laser field of linear polarization are studied using the S-matrix theory in the length gauge. The PADs show main lobes along the laser polarization and jet-like structures sticking from the waist of main lobes. Our previous prediction, based on a nonperturbative scattering theory of photoionization developed by Guo et al, showing that the number of jets on one side of PADs may increase by one, three, or other odd numbers and may decrease by one when one more photon is absorbed, is confirmed by this treatment. Within the strong-field approximation, good agreement is obtained between these two quite different treatments. We further study the influence of the Coulomb attraction to PADs, by taking a Coulomb-Volkov state as the continuum state of photoelectrons. We find that under the influence of the Coulomb attraction, the PADs change greatly but the predicted phenomena still appear. This study verifies that the jet-like structures have no relation with the angular momentum of photoelectrons.

  16. ATOMIC AND MOLECULAR PHYSICS: First-Principles Study on Native Defect Complexes in InN

    NASA Astrophysics Data System (ADS)

    Zhao, Feng-Qi; Shi, Jun-Jie; Yang, Mao

    2010-01-01

    We present first-principles calculations of the formation energy of different native defects and their complexes in wurtzite InN using density-functional theory and the pseudopotential plane-wave method. Our calculations are aimed in the three cases: N/In = 1, N/In > 1 (N-rich), and N/In < 1 (In-rich). Our results indicate that the antisite defect has the lowest formation energy under N/In = 1. The formation energy of nitrogen interstitial (nitrogen vacancy) defect is significantly low under the N-rich (In-rich) condition. Thus the antisite defect is an important defect if N/In = 1, and the nitrogen interstitial (nitrogen vacancy) defect is a vital defect under the N-rich (In-rich) condition. The atomic site relaxation around the nitrogen interstitial and vacancy is investigated. Our calculations show that the nitrogen vacancy cannot be observed although it is one of the most important defects in InN. Our results are confirmed by experiments.

  17. 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.

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

    PubMed

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

    2012-01-01

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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Chettle, David R.

    1995-08-01

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

  5. Dynamical analysis of an accelerator-based fluid-fueled subcritical radioactive waste burning system

    NASA Astrophysics Data System (ADS)

    Woosley, Michael Louis, Jr.

    The recent revival of interest in accelerator-driven subcritical fluid-fueled systems is documented. Several important applications of these systems are mentioned. In particular, new applications have focused on the destruction of high-level radioactive waste. Systems can be designed to quickly destroy the actinides and long-lived fission products from light water reactor fuel, weapons plutonium, and other high-level defense wastes. The proposed development of these systems is used to motivate the need for the development of dynamic analysis methods for their nuclear kinetics. A physical description of the Los Alamos Accelerator-Based Conversion (ABC) concept is provided. This system is used as the basis for the kinetics study in this research. The current approach to the dynamic simulation of an accelerator-driven subcritical fluid-fueled system includes three elements: A discrete ordinates model is used to calculate the flux distribution for the source-driven system; A nodal convection model is used to calculate time-dependent isotope and temperature distributions which impact reactivity; A nodal importance weighting model is used to calculate the reactivity impact of temperature and isotope distributions and to feed this information back to the time-dependent nodal convection model. Specific transients which have been analyzed with the current modeling system are discussed. These transients include loss-of-flow and loss-of-cooling accidents, xenon and samarium transients, and cold-plug and overfueling events. The results of various transients have uncovered unpredictable behavior, unresolved design issues, and the need for active control. Modest initiating events can cause significant swings in system temperature and power. The circulation of the fluid fuel can lead to oscillations on the relatively short scale of the loop circulation time. The system responds quickly to reactivity changes because the large neutron source overwhelms the damping effect of delayed

  6. Nanoscale investigation of platinum nanoparticles on strontium titanium oxide grown via physical vapor deposition and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Christensen, Steven Thomas

    This dissertation examines growth of platinum nanoparticles from vapor deposition on SrTiO3 using a characterization approach that combines imaging techniques and X-ray methods. The primary suite of characterization probes includes atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray absorption spectroscopy (XAS). The vapor deposition techniques include physical vapor deposition (PVD) by evaporation and atomic layer deposition (ALD). For the PVD platinum study, AFM/XRF showed ˜10 nm nanoparticles separated by an average of 100 nm. The combination of AFM, GISAXS, and XRF indicated that the nanoparticles observed with AFM were actually comprised of closely spaced, smaller nanoparticles. These conclusions were supported by high-resolution SEM. The unusual behavior of platinum nanoparticles to aggregate without coalescence or sintering was observed previously by other researchers using transmissision electron microscopy (TEM). Platinum nanoparticle growth was also investigated on SrTiO3 (001) single crystals using ALD to nucleate nanoparticles that subsequently grew and coalesced into granular films as the ALD progresses. The expected growth rate for the early stages of ALD showed a two-fold increase which was attributed to the platinum deposition occurring faster on the bare substrate. Once the nanoparticles had coalesced into a film, steady state ALD growth proceeded. The formation of nanoparticles was attributed to the atomic diffusion of platinum atoms on the surface in addition to direct growth from the ALD precursor gases. The platinum ALD nanoparticles were also studied on SrTiO3 nanocube powders. The SrTiO3 nanocubes average 60 nm on a side and the cube faces have a {001} orientation. The ALD proceeded in a similar fashion as on the single crystal substrates where the deposition rate was twice as fast as the steady state growth rate. The Pt nanoparticle

  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. Physics.

    PubMed

    Bromley, D A

    1980-07-01

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

  10. ATOMIC AND MOLECULAR PHYSICS: Single atoms transferring between a magneto-optical trap and a far-off-resonance optical dipole trap

    NASA Astrophysics Data System (ADS)

    He, Jun; Wang, Jing; Yang, Bao-Dong; Zhang, Tian-Cai; Wang, Jun-Min

    2009-08-01

    Based on our work on single cesium atoms trapped in a large-magnetic-gradient vapour-cell magneto-optical trap (MOT), the signal-to-noise ratio (SNR) is remarkably improved. Also a far-off-resonance optical dipole trap (FORT) formed by a strongly-focused 1064 nm single frequency Nd:YVO4 laser beam is introduced. One cesium atom is prepared in the MOT, and then it can transfer successfully between the MOT and the FORT which is overlapped with the MOT. Utilizing the effective transfer, the lifetime of single atoms trapped in the FORT is measured to be 6.9 ± 0.3 s. Thus we provide a system where the atomic qubit can be coherently manipulated.

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

    NASA Astrophysics Data System (ADS)

    2016-02-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Gordillo-Vazquez, F. J.

    2009-07-01

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

  16. 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

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

    PubMed

    Kiracofe, Daniel; Melcher, John; Raman, Arvind

    2012-01-01

    Dynamic atomic force microscopy (dAFM) continues to grow in popularity among scientists in many different fields, and research on new methods and operating modes continues to expand the resolution, capabilities, and types of samples that can be studied. But many promising increases in capability are accompanied by increases in complexity. Indeed, interpreting modern dAFM data can be challenging, especially on complicated material systems, or in liquid environments where the behavior is often contrary to what is known in air or vacuum environments. Mathematical simulations have proven to be an effective tool in providing physical insight into these non-intuitive systems. In this article we describe recent developments in the VEDA (virtual environment for dynamic AFM) simulator, which is a suite of freely available, open-source simulation tools that are delivered through the cloud computing cyber-infrastructure of nanoHUB (www.nanohub.org). Here we describe three major developments. First, simulations in liquid environments are improved by enhancements in the modeling of cantilever dynamics, excitation methods, and solvation shell forces. Second, VEDA is now able to simulate many new advanced modes of operation (bimodal, phase-modulation, frequency-modulation, etc.). Finally, nineteen different tip-sample models are available to simulate the surface physics of a wide variety different material systems including capillary, specific adhesion, van der Waals, electrostatic, viscoelasticity, and hydration forces. These features are demonstrated through example simulations and validated against experimental data, in order to provide insight into practical problems in dynamic AFM. PMID:22299957

  18. 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

  19. 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.

  20. 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.

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

    PubMed

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

    2013-12-01

    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.

  2. Accelerator-based epithermal neutron sources for boron neutron capture therapy of brain tumors.

    PubMed

    Blue, Thomas E; Yanch, Jacquelyn C

    2003-01-01

    This paper reviews the development of low-energy light ion accelerator-based neutron sources (ABNSs) for the treatment of brain tumors through an intact scalp and skull using boron neutron capture therapy (BNCT). A major advantage of an ABNS for BNCT over reactor-based neutron sources is the potential for siting within a hospital. Consequently, light-ion accelerators that are injectors to larger machines in high-energy physics facilities are not considered. An ABNS for BNCT is composed of: (1) the accelerator hardware for producing a high current charged particle beam, (2) an appropriate neutron-producing target and target heat removal system (HRS), and (3) a moderator/reflector assembly to render the flux energy spectrum of neutrons produced in the target suitable for patient irradiation. As a consequence of the efforts of researchers throughout the world, progress has been made on the design, manufacture, and testing of these three major components. Although an ABNS facility has not yet been built that has optimally assembled these three components, the feasibility of clinically useful ABNSs has been clearly established. Both electrostatic and radio frequency linear accelerators of reasonable cost (approximately 1.5 M dollars) appear to be capable of producing charged particle beams, with combinations of accelerated particle energy (a few MeV) and beam currents (approximately 10 mA) that are suitable for a hospital-based ABNS for BNCT. The specific accelerator performance requirements depend upon the charged particle reaction by which neutrons are produced in the target and the clinical requirements for neutron field quality and intensity. The accelerator performance requirements are more demanding for beryllium than for lithium as a target. However, beryllium targets are more easily cooled. The accelerator performance requirements are also more demanding for greater neutron field quality and intensity. Target HRSs that are based on submerged-jet impingement and

  3. 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.

  4. Specific contributions of the Dutch programme ``RAS'' towards accelerator-based transmutation

    NASA Astrophysics Data System (ADS)

    Abrahams, K.; Franken, W. M. P.; Bultman, J. H.; Heil, J. A.; Koning, A. J.

    1995-09-01

    Accelerator-based transmutation is being studied by ECN within its general nuclear waste transmutation programme RAS. In this paper the following contributions are presented: 1) Evaluation of cross sections at intermediate energies, within an international frame given by NEA, 2) Cell calculations on the equilibration of transuranium actinides in thermal molten-salt transmuters, 3) Irradiation facilities at the European research reactor HFR in Petten, which have been constructed with the purpose to demonstrate and investigate the transmutation of waste in a high neutron flux, 4) Studies of accelerator-based neutron generating systems to transmute neptunium and technetium, 5) Comparison of several systems on the basis of criteria for successful nuclear waste-management.

  5. The Nature of Atoms.

    ERIC Educational Resources Information Center

    Holden, Alan

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

  6. Treatment planning capability assessment of a beam shaping assembly for accelerator-based BNCT.

    PubMed

    Herrera, M S; González, S J; Burlon, A A; Minsky, D M; Kreiner, A J

    2011-12-01

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) a theoretical study was performed to assess the treatment planning capability of different configurations of an optimized beam shaping assembly for such a facility. In particular this study aims at evaluating treatment plans for a clinical case of Glioblastoma.

  7. 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.

  8. ATOMIC AND MOLECULAR PHYSICS: Generation of a Super Strong Attosecond Pulse from an Atomic Superposition State Irradiated by a Shape-Optimized Short Pulse

    NASA Astrophysics Data System (ADS)

    Guo, Fu-Ming; Yang, Yu-Jun; Jin, Ming-Xing; Ding, Da-Jun; Zhu, Qi-Ren

    2009-11-01

    Using a linearly polarized, phase-stabilized 3-fs driving pulse of 800 nm central wavelength shape-optimized on its ascending edge by its an amplitude-reduced pulse irradiating on a superposition state of the helium atom, we demonstrate theoretically the generation of a super strong isolated 176-attosecond pulse in the spectral region of 93-124 eV. The unusually high intensity of this attosecond pulse is marked by the Rabi-like oscillations emerging in the time-dependent populations of the ground state and the continuum during the occurrence of the electron recombination, which is for the first time observed in this work.

  9. PHYSICAL BASIS OF QUANTUM ELECTRONICS: Long-lived positronium atom in the field of an optical laser

    NASA Astrophysics Data System (ADS)

    Gadomskii, Oleg N.; Idiatullov, T. T.

    1998-06-01

    The problem of the interaction of a positronium atom with the field of optical and annihilation photons is considered. The solution obtained for the occupation numbers is used to study kinetics of the annihilation decay of a para-positronium atom from two (for example, 1S and 2P) states participating in stimulated optical transitions excited by a laser. It is shown that a nonexponential time dependence of the occupation numbers is observed under the conditions of a nonlinear coherent interaction of a positronium atom with the field of optical and annihilation photons, and that in some cases there is a possibility of appearance of a long-lived state of a positronium atom with a lifetime hundreds of times longer than the lifetime of a positronium atom in the 1S state.

  10. 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.

  11. PHYSICAL BASIS OF QUANTUM ELECTRONICS: Variation of the emission characteristics of an atom located near an ideally conducting conical surface

    NASA Astrophysics Data System (ADS)

    Klimov, Vasilii V.; Perventsev, Ya A.

    1999-10-01

    The line width and the emission frequency of an atom located near the vertex of an ideally conducting cone or inside a conical cavity in an ideal conductor are analysed. It is shown that the influence of the vertex diminishes with decrease in the vertex angle. On the other hand, the line width and the emission frequency of an atom located in a conical cavity may both increase and decrease greatly, depending on the position of the atom and on the vertex angle of the cavity. The results obtained may prove useful in the development of both monatomic microlasers and spectrally selective near-field nanoscopes.

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

    NASA Astrophysics Data System (ADS)

    Cartagena-Rivera, Alexander X.

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

  13. Modelling of non-LTE atomic physics processes in hot dense plasmas during the interaction with an intense short pulse laser

    NASA Astrophysics Data System (ADS)

    Davis, J.; Petrov, G. M.

    2014-05-01

    The implicit 2D3V particle-in-cell (PIC) code developed to study the interaction of intense lasers with matter (Petrov and Davis 2008 Comput. Phys. Commun. 179 868-80 2011 Phys. Plasmas 18 073102) has been extended to include atomic physics under extreme energy density conditions. The atomic physics model is applied to aluminium. Each ionization stage contains two levels: one ground and one lumped excited state, for which various atomic physics processes such as optical field ionization, collisional ionization, excitation, de-excitation and radiative decay describe the population density. Two-dimensional PIC simulations have been carried out for laser pulses with peak intensity 1 × 1020 W cm-2, pulse duration 60 fs, spot size 3 µm and energy 0.75 J interacting with ultrathin (0.2 µm) Al foil. Radiation emitted during the laser-target interaction is computed by accounting for both bound-bound transitions and bremsstrahlung radiation. We demonstrate that the radiation signature of laser-produced plasma can be used as a complementary tool to other diagnostic techniques used in laser-plasma interactions. Finally, results from the PIC model are compared to equilibrium calculations (Maxwell-Boltzmann and Saha). In the early stages of laser-plasma interactions (<100 fs) the plasma is far from equilibrium and equilibrium models can not be applied with confidence to model the plasma.

  14. 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

  15. PHYSICAL BASIS OF QUANTUM ELECTRONICS: Properties of spontaneous radiation of an atom located near a cluster of two spherical nanoparticles

    NASA Astrophysics Data System (ADS)

    Guzatov, D. V.; Klimov, Vasilii V.

    2005-10-01

    The analytic solution of the problem of spontaneous decay of an atom near a cluster of two perfectly conducting nanospheres is found. It is shown that spontaneous decay rates can considerably decrease or increase depending on the system geometry. In particular, within the framework of our model, the decay rate of an atom located between closely spaced spheres and having the transition dipole moment directed along the symmetry axis can be arbitrarily high.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Development of a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

    PubMed

    Kreiner, A J; Castell, W; Di Paolo, H; Baldo, M; Bergueiro, J; Burlon, A A; Cartelli, D; Vento, V Thatar; Kesque, J M; Erhardt, J; Ilardo, J C; Valda, A A; Debray, M E; Somacal, H R; Sandin, J C Suarez; Igarzabal, M; Huck, H; Estrada, L; Repetto, M; Obligado, M; Padulo, J; Minsky, D M; Herrera, M; Gonzalez, S J; Capoulat, M E

    2011-12-01

    We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas.

  1. 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.

  2. 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."

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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?

  8. 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?

  9. Atom Interferometry

    ScienceCinema

    Mark Kasevich

    2016-07-12

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

  10. 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)

  11. 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

  12. 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.

  13. ATOMIC AND MOLECULAR PHYSICS: Investigation of odd-parity Rydberg states of Eu I with autoionization detection

    NASA Astrophysics Data System (ADS)

    Xiao, Ying; Dai, Chang-Jian; Qin, Wen-Jie

    2009-10-01

    Isolated-core-excitation (ICE) scheme and autoionization detection are employed to study the bound Rydberg states of europium atom. The high-lying states with odd parity have been measured using the autoionization detection method with three different excitation paths via 4f76s6p[8P5/2], 4f76s6p[8P7/2] and 4f76s6p[8P9/2] intermediate states, respectively. In this paper the spectra of bound Rydberg states of Eu atom are reported, which cover the energy regions from 36000 cm-1 to 38250 cm-1 and from 38900 cm-1 to 39500 cm-1. The study provides the information about level energy, the possible J values and relative line intensity as well as the effective principal quantum number n* for these states. This work not only confirms the previous results of many states, but also discovers 11 new Rydberg states of Eu atom.

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

    PubMed

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

    2012-01-01

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

  15. 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.

  16. 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)

  17. 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)

  18. 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.

  19. 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.

  20. Multipurpose applications of the accelerator-based neutron source[1pt] GENEPI2

    NASA Astrophysics Data System (ADS)

    Villa, F.; Baylac, M.; Billebaud, A.; Boge, P.; Cabanel, T.; Labussière, E.; Méplan, O.; Rey, S.

    2016-11-01

    GENEPI2 (GEnérateur de NEutrons Pulsé Intense) is an accelerator-based neutron source operating at LPSC laboratory in Grenoble (France). The neutrons are produced at 2.5MeV or 14.2MeV trough fusion reactions. GENEPI2 specifications allow performing efficiently accelerated irradiation tests of integrated circuits. This facility can also be operated to test and calibrate different types of detectors. This paper will describe the facility and its performances. Then, measurements of the neutron production will be presented as well as different types of experiments and irradiations. Finally, we describe upgrades undertaken to increase the neutron flux and optimize the facility for multiple applications.

  1. 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.

  2. 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.

  3. Atom probe tomography

    SciTech Connect

    Miller, M.K.; Forbes, R.G.

    2009-06-15

    This introductory tutorial describes the technique of atom probe tomography for materials characterization at the atomic level. The evolution of the technique from the initial atom probe field ion microscope to today's state-of-the-art three dimensional atom probe is outlined. An introduction is presented on the basic physics behind the technique, the operation of the instrument, and the reconstruction of the three-dimensional data. The common methods for analyzing the three-dimensional atom probe data, including atom maps, isoconcentration surfaces, proximity histograms, maximum separation methods, and concentration frequency distributions, are described.

  4. 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.

  5. 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.

  6. Physics

    NASA Astrophysics Data System (ADS)

    Campbell, Norman Robert

    2013-03-01

    Preface; Introduction; Part I. The Propositions of Science: 1. The subject matter of science; 2. The nature of laws; 3. The nature of laws (contd); 4. The discovery and proof of laws; 5. The explanation of laws; 6. Theories; 7. Chance and probability; 8. The meaning of science; 9. Science and philosophy; Part II. Measurement: 10. Fundamental measurement; 11. Physical number; 12. Fractional and negative magnitudes; 13. Numerical laws and derived magnitudes; 14. Units and dimensions; 15. The uses of dimensions; 16. Errors of measurement; methodical errors; 17. Errors of measurement; errors of consistency and the adjustment of observations; 18. Mathematical physics; Appendix; Index.

  7. Effects of the physical properties of atomic layer deposition grown seeding layers on the preparation of ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Ladanov, Mikhail; Algarin-Amaris, Paula; Villalba, Pedro; Emirov, Yusuf; Matthews, Garrett; Thomas, Sylvia; Ram, Manoj K.; Kumar, Ashok; Wang, Jing

    2013-11-01

    Zinc oxide (ZnO) nanowires are growing in interest as the number of devices for which they are well suited increases. Success in these applications requires defined and controlled geometric incorporation of the wires into the various platforms. Therefore, establishing the ability to tailor the growth ZnO nanowires to produce specified sizes, surface densities, and orientation will be important. In the reported work, the effects of the seeding layer on these factors were accessed. Atomic layer deposition (ALD) was used to produce thin films of ZnO under varying growth and post-processing conditions. These films were fully characterized, including their thickness, surface roughness, and crystalline orientation. Using these well-defined films as the seeding layer, ZnO nanowires were grown and subsequently characterized in terms of morphology and crystalline properties. It was shown that the resulting nanowire properties are dependent upon the nature of the seeding layer, and careful production of the seeding layer allows for some control over these properties.

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

    PubMed

    Solares, Santiago D

    2014-01-01

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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.}

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

    NASA Astrophysics Data System (ADS)

    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-BeF2 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.

  15. 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.

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

    PubMed Central

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

    2015-01-01

    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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  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.

  4. 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.

  5. 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

  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. Prospect for application of compact accelerator-based neutron source to neutron engineering diffraction

    NASA Astrophysics Data System (ADS)

    Ikeda, Yoshimasa; Taketani, Atsushi; Takamura, Masato; Sunaga, Hideyuki; Kumagai, Masayoshi; Oba, Yojiro; Otake, Yoshie; Suzuki, Hiroshi

    2016-10-01

    A compact accelerator-based neutron source has been lately discussed on engineering applications such as transmission imaging and small angle scattering as well as reflectometry. However, nobody considers using it for neutron diffraction experiment because of its low neutron flux. In this study, therefore, the neutron diffraction experiments are carried out using Riken Accelerator-driven Compact Neutron Source (RANS), to clarify the capability of the compact neutron source for neutron engineering diffraction. The diffraction pattern from a ferritic steel was successfully measured by suitable arrangement of the optical system to reduce the background noise, and it was confirmed that the recognizable diffraction pattern can be measured by a large sampling volume with 10 mm in cubic for an acceptable measurement time, i.e. 10 min. The minimum resolution of the 110 reflection for RANS is approximately 2.5% at 8 μs of the proton pulse width, which is insufficient to perform the strain measurement by neutron diffraction. The moderation time width at the wavelength corresponding to the 110 reflection is estimated to be approximately 30 μs, which is the most dominant factor to determine the resolution. Therefore, refinements of the moderator system to decrease the moderation time by decreasing a thickness of the moderator or by applying the decoupler system or application of the angular dispersive neutron diffraction technique are important to improve the resolution of the diffraction experiment using the compact neutron source. In contrast, the texture evolution due to plastic deformation was successfully observed by measuring a change in the diffraction peak intensity by RANS. Furthermore, the volume fraction of the austenitic phase in the dual phase mock specimen was also successfully evaluated by fitting the diffraction pattern using a Rietveld code. Consequently, RANS has been proved to be capable for neutron engineering diffraction aiming for the easy access

  9. 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.

  10. PREFACE: The Joint 16th Europhysics Conference on Atomic and Molecular Physics of Ionized Gases--5th International Conference on Reactive Plasmas

    NASA Astrophysics Data System (ADS)

    Sadeghi, N.

    2003-11-01

    The first joint meeting of the Europhysics Conference on Atomic and Molecular Physics of Ionized Gases (ESCAMPIG), the International Conference on Reactive Plasmas (ICRP) and the Symposium on Plasma Processing (SPP) was held in Grenoble, France between 14 and 18 July 2002. ESCAMPIG is an important biennial European event at which academics and industrialists working in low temperature plasma science meet. ICRP and SPP are Japanese triennial and annual meetings covering the entire field of reactive plasmas: generation, diagnostics and modelling of plasmas and their interaction with surfaces, and their applications. This ESCAMPIG 16th--ICRP 5th joint conference was organized under the sponsorship of the European Physical Society (EPS), the Japan Society of Applied Physics (JSAP), University Joseph Fourier (UJF) and Centre National de la Recherche Scientifique (CNRS). The scientific scope of this joint conference was focused on both experimental and theoretical aspects of physics of ionized gases and on its industrial applications. It covered the following topics: bullet atomic and molecular processes in plasmas bullet particle energy distribution functions bullet discharge physics: sheathes, transport processes and modelling bullet plasma diagnostics bullet laser and particle beam assisted plasma processes bullet physical basis of plasma chemistry and plasma--surface interactions bullet production and control of reactive plasmas bullet etching, deposition and cleaning bullet environmental and other applications. The ESCAMPIG 16th--ICRP 5th joint conference was attended by 379 scientists from 26 countries. 22 invited papers were presented. Most of these papers are published in this special issue. In addition, 16 contributed papers were selected by the joint International Scientific Committee (ISC) for oral presentation as a `hot topic'. Beside this, two workshops were held on `Recent developments in plasma monitoring for microelectronics', organized by Professor H

  11. Development and construction of a neutron beam line for accelerator-based boron neutron capture synovectomy.

    PubMed

    Gierga, D P; Yanch, J C; Shefer, R E

    2000-01-01

    A potential application of the 10B(n, alpha)7Li nuclear reaction for the treatment of rheumatoid arthritis, termed Boron Neutron Capture Synovectomy (BNCS), is under investigation. In an arthritic joint, the synovial lining becomes inflamed and is a source of great pain and discomfort for the afflicted patient. The goal of BNCS is to ablate the synovium, thereby eliminating the symptoms of the arthritis. A BNCS treatment would consist of an intra-articular injection of boron followed by neutron irradiation of the joint. Monte Carlo radiation transport calculations have been used to develop an accelerator-based epithermal neutron beam line for BNCS treatments. The model includes a moderator/reflector assembly, neutron producing target, target cooling system, and arthritic joint phantom. Single and parallel opposed beam irradiations have been modeled for the human knee, human finger, and rabbit knee joints. Additional reflectors, placed to the side and back of the joint, have been added to the model and have been shown to improve treatment times and skin doses by about a factor of 2. Several neutron-producing charged particle reactions have been examined for BNCS, including the 9Be(p,n) reaction at proton energies of 4 and 3.7 MeV, the 9Be(d,n) reaction at deuteron energies of 1.5 and 2.6 MeV, and the 7Li(p,n) reaction at a proton energy of 2.5 MeV. For an accelerator beam current of 1 mA and synovial boron uptake of 1000 ppm, the time to deliver a therapy dose of 10,000 RBEcGy ranges from 3 to 48 min, depending on the treated joint and the neutron producing charged particle reaction. The whole-body effective dose that a human would incur during a knee treatment has been estimated to be 3.6 rem or 0.75 rem, for 1000 ppm or 19,000 ppm synovial boron uptake, respectively, although the shielding configuration has not yet been optimized. The Monte Carlo design process culminated in the construction, installation, and testing of a dedicated BNCS beam line on the high

  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. 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

  14. 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.

  15. Physical properties of as-prepared and post-annealed TiO2 layers by atomic layer deposition and their cell performance

    NASA Astrophysics Data System (ADS)

    Kim, Min Ji; Ahn, Kyun; Choi, Hun Seok; Pham-Cong, De; Gao, Ying Jun; Cho, Jin Hyuk; Park, Cheul Un; Cho, Chae-Ryong

    2016-01-01

    We report on the physical properties of TiO2 blocking layers with various thicknesses in both the as-prepared and the post-annealed states and on their cell performances in dye-sensitized solar cells (DSSCs). The TiO2 layers of various thicknesses (up to 50 nm) were prepared on fluorine-doped SnO2/glass substrates by using atomic layer deposition. The electron lifetime of the DSSCs was observed to depend critically on both the thickness and the annealing treatment for TiO2 layers with thicknesses up to 10 nm. However, for thicknesses above 20 nm, the cell performance of the DSSCs decreased because of increases in the defect density and charge recombination. We conclude that the cell efficiency of DSSCs with a 10-nm-thick TiO2 layer is higher than those of DSSCs with layers of other thicknesses; in addition, the cell characteristics of the post-annealed structures were better than those of the as-prepared ones.

  16. 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

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. A difference in using atomic layer deposition or physical vapour deposition TiN as electrode material in metal-insulator-metal and metal-insulator-silicon capacitors.

    PubMed

    Groenland, A W; Wolters, R A M; Kovalgin, A Y; Schmitz, J

    2011-09-01

    In this work, metal-insulator-metal (MIM) and metal-insulator-silicon (MIS) capacitors are studied using titanium nitride (TiN) as the electrode material. The effect of structural defects on the electrical properties on MIS and MIM capacitors is studied for various electrode configurations. In the MIM capacitors the bottom electrode is a patterned 100 nm TiN layer (called BE type 1), deposited via sputtering, while MIS capacitors have a flat bottom electrode (called BE type 2-silicon substrate). A high quality 50-100 nm thick SiO2 layer, made by inductively-coupled plasma CVD at 150 degrees C, is deposited as a dielectric on top of both types of bottom electrodes. BE type 1 (MIM) capacitors have a varying from low to high concentration of structural defects in the SiO2 layer. BE type 2 (MIS) capacitors have a low concentration of structural defects and are used as a reference. Two sets of each capacitor design are fabricated with the TiN top electrode deposited either via physical vapour deposition (PVD, i.e., sputtering) or atomic layer deposition (ALD). The MIM and MIS capacitors are electrically characterized in terms of the leakage current at an electric field of 0.1 MV/cm (I leak) and for different structural defect concentrations. It is shown that the structural defects only show up in the electrical characteristics of BE type 1 capacitors with an ALD TiN-based top electrode. This is due to the excellent step coverage of the ALD process. This work clearly demonstrates the sensitivity to process-induced structural defects, when ALD is used as a step in process integration of conductors on insulation materials.

  2. PHYSICAL BASIS OF QUANTUM ELECTRONICS: Frequency shift of radiation of an atom near a cluster of two perfectly conducting spherical nanoparticles

    NASA Astrophysics Data System (ADS)

    Guzatov, D. V.

    2005-10-01

    Expressions for the frequency shift of radiation of an atom located near a cluster of two perfectly conducting spherical nanoparticles are obtained within the framework of a classical model. The asymptotic expression is found for the radiation frequency shift of an atom located between spheres approaching each other.

  3. 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

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

    PubMed

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

    2015-03-01

    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 10(5) n/cm(2)/s with sufficient accuracy. The SOF detector will be useful for phantom experiments with BNCT neutron fields from low-current accelerator-based neutron sources.

  5. 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.

  6. Nuclear physics. Fourth edition

    SciTech Connect

    Wehr, M.R.; Richards, J.A.; Adair, T.W.

    1984-01-01

    This book is designed to be an extension of the introductory college physics course into the realm of atomic physics: It should give students a proficiency in this field comparable to their proficiency in mechanics, heat, sound, light and electricity. Topics included: the atomic view of matter; the atomic view of electricity; the atomic view of radiation; the atomic models of Rutherford and Bohr; relativity; x-rays; waves and particles; quantum mechanics; the atomic view of solids; natural radioactivity; nuclear reactions and artificial radioactivity; nuclear energy; and high-energy physics.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. An accelerator-based epithermal neutron beam design for BNCT and dosimetric evaluation using a voxel head phantom.

    PubMed

    Lee, Deok-jae; Han, Chi Young; Park, Sung Ho; Kim, Jong Kyung

    2004-01-01

    The beam shaping assembly design has been investigated in order to improve the epithermal neutron beam for accelerator-based boron neutron capture therapy in intensity and quality, and dosimetric evaluation for the beams has been performed using both mathematical and voxel head phantoms with MCNP runs. The neutron source was assumed to be produced from a conventional 2.5 MeV proton accelerator with a thick (7)Li target. The results indicate that it is possible to enhance epithermal neutron flux remarkably as well as to embody a good spectrum shaping to epithermal neutrons only with the proper combination of moderator and reflector. It is also found that a larger number of thermal neutrons can reach deeply into the brain and, therefore, can reduce considerably the treatment time for brain tumours. Consequently, the epithermal neutron beams designed in this study can treat more effectively deep-seated brain tumours.

  14. ATOMIC AND MOLECULAR PHYSICS: Unique Magnetic Moment and Electronic Properties for Fe(MgO)n(n = 1-8) Clusters: First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Ge, Gui-Xian; Jing, Qun; Yang, Zeng-Qiang; Luo, You-Hua

    2009-08-01

    The geometries and electronic properties of Fe(MgO)n are systematically investigated by the density functional theory. The results show that the doped Fe atom is prone to bond with the O atom, and Fe almost does not disturb the frame of (MgO)n. The second-order energy difference, the fragmentation energies and the electron affinities show that Fe(MgO)4 and Fe(MgO)6 possess relatively higher stabilities. The HOMO-LUMO gaps of Fe(MgO)n decrease obviously as compared with (MgO)n. Almost equal unpaired electrons of the 3d state of the Fe atom in Fe(MgO)n result in a nearly equal magnetic moment of Fe(MgO)n.

  15. 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

  16. 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…

  17. 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…

  18. Conformal atoms in Supergravity

    NASA Astrophysics Data System (ADS)

    Jankowski, Jakub

    2016-01-01

    In this note, we summarize recent attempts to construct holographic models of atoms and lattices in the context of applications to solid state physics. The simplest setup turned out to impose strong constraints on the choice of matter interactions of dual gravitational theory.

  19. 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.

  20. The Coulomb law and atomic levels in a superstrong B. Talk at the 1st International Conference on New Frontiers in Physics

    NASA Astrophysics Data System (ADS)

    Vysotsky, M. I.

    2014-04-01

    The spectrum of atomic levels of hydrogen-like ions originating from the lowest Landau level in an external homogeneous superstrong magnetic field is obtained. The influence of the screening of the Coulomb potential on the values of critical nuclear charges is studied.

  1. Resonance Radiation and Excited Atoms

    NASA Astrophysics Data System (ADS)

    Mitchell, Allan C. G.; Zemansky, Mark W.

    2009-06-01

    1. Introduction; 2. Physical and chemical effects connected with resonance radiation; 3. Absorption lines and measurements of the lifetime of the resonance state; 4. Collision processes involving excited atoms; 5. The polarization of resonance radiation; Appendix; Index.

  2. 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.

  3. 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.

  4. 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.

  5. 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)…

  6. ATOMIC AND MOLECULAR PHYSICS: Bose-Einstein Condensates in a One-Dimensional Optical Lattice: from Superfluidity to Number-Squeezed States

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Rui; Yang, Lu; Tan, Xin-Zhou; Xiong, Hong-Wei; Lu, Bao-Long

    2009-08-01

    We study the phase coherence property of Bose-Einstein condensates confined in a one-dimensional optical lattice formed by a standing-wave laser field. The lattice depth is determined using a method of Kapitza-Dirac scattering between a condensate and a short pulse lattice potential. Condensates are then adiabatically loaded into the optical lattice. The phase coherence property of the confined condensates is reflected by the interference patterns of the expanded atomic cloud released from the optical lattice. For weak lattice, nearly all of the atoms stay in a superfluid state. However, as the lattice depth is increased, the phase coherence of the whole condensate sample is gradually lost, which confirms that the sub-condensates in each lattice well have evolved into number-squeezed states.

  7. Atomic Parity Violation, Muon Pair Production in e+e - Collisions and Detection of CDM WIMP-Physics Related to Neutral Vector Boson D1

    NASA Astrophysics Data System (ADS)

    Senju, H.

    1999-11-01

    In our preon model there exists a neutral vector boson D1 which is an isoscalar partner of W(Z) in the vector boson octet. It is shown that the exchange of a D1 of about 1 TeV mass naturally explains a positive excess of the weak charge of atomic cesium recently observed. Other processes occurring through the D1 exchange are discussed, including the detection of CDM WIMP.

  8. Dense atom clouds in a holographic atom trap.

    PubMed

    Newell, R; Sebby, J; Walker, T G

    2003-07-15

    We demonstrate the production of high-density cold 87Rb samples (2 x 10(14) atoms/cm3) in a simple optical lattice formed with YAG light that is diffracted from a holographic phase plate. A loading protocol is described that results in 10,000 atoms per 10 microm x 10 microm x 100 microm unit cell of the lattice site. Rapid free evaporation leads to a temperature of 50 microK and phase space densities of 1/150 within 50 ms. The resulting small, high-density atomic clouds are very attractive for a number of experiments, including ultracold Rydberg atom physics.

  9. NONLINEAR ATOM OPTICS

    SciTech Connect

    T. MILONNI; G. CSANAK; ET AL

    1999-07-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objectives were to explore theoretically various aspects of nonlinear atom optics effects in cold-atom waves and traps. During the project a major development occurred the observation, by as many as a dozen experimental groups, of Bose-Einstein condensation (BEC) in cold-atom traps. This stimulated us to focus our attention on those aspects of nonlinear atom optics relating to BEC, in addition to continuing our work on a nonequilibrium formalism for dealing with the interaction of an electromagnetic field with multi-level atomic systems, allowing for macroscopic coherence effects such as BEC. Studies of several problems in BEC physics have been completed or are near completion, including the suggested use of external electric fields to modify the nature of the interatomic interaction in cold-atom traps; properties of two-phase condensates; and molecular loss processes associated with BEC experiments involving a so-called Feshbach resonance.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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,…

  17. 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…

  18. ATOMIC AND MOLECULAR PHYSICS: Retrieval of Electron Return Time from High-order Harmonics Generated in a Mixture of He and Ne Gases

    NASA Astrophysics Data System (ADS)

    Jin, Cheng; Zhou, Xiao-Xin; Zhao, Song-Feng

    2010-04-01

    In terms of single-atom induced dipole moment by Lewenstein model, we present the macroscopic high-order harmonic generation from mixed He and Ne gases with different mixture ratios by solving three-dimensional Maxwell's equation of harmonic held. And then we show the validity of mixture formulation by Wagner et al. [Phys. Rev. A 76 (2007) 061403(R)] in macroscopic response level. Finally, using least squares fitting we retrieve the electron return time of short trajectory by formulation in Kanai et al. [Phys. Rev. Lett. 98 (2007) 153904] when the gas jet is put after the laser focus.

  19. ATOMIC AND MOLECULAR PHYSICS Generation of Broadband Attosecond Pulse via Controlling Quantum Path by Two Color Field in Long Wavelength Driving Regime

    NASA Astrophysics Data System (ADS)

    Luo, Jiang-Hua

    2011-01-01

    In this paper, we have investigated theoretically the high harmonic generation form helium atom in long wavelength driving regime at 2000 nm through solving time-dependent Schrödinger equation. By adding a second harmonic pulse (1000 nm) and a UV attosecond pulse (200 nm) to the driving field, an efficient method for picking out and enhancing ionization path to generate high-yield supercontinuum harmonics is realized, and then an isolated sub-100 as pulse with a bandwidth of 190 eV is significantly obtained.

  20. 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)

  1. 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)

  2. Electrostatic design and beam transport for a folded tandem electrostatic quadrupole accelerator facility for accelerator-based boron neutron capture therapy.

    PubMed

    Vento, V Thatar; Bergueiro, J; Cartelli, D; Valda, A A; Kreiner, A J

    2011-12-01

    Within the frame of an ongoing project to develop a folded Tandem-Electrostatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT), we discuss here the electrostatic design of the machine, including the accelerator tubes with electrostatic quadrupoles and the simulations for the transport and acceleration of a high intensity beam.

  3. 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.

  4. Atomic and molecular science with synchrotron radiation

    SciTech Connect

    Not Available

    1989-11-07

    This paper discusses the following topics: electron correlation in atoms; atomic innershell excitation and decay mechanisms; timing experiments; x-ray scattering; properties of ionized species; electronic properties of actinide atoms; total photon-interaction cross sections; and molecular physics. 66 refs. (LSP)

  5. 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)

  6. Physical properties of poly(lactic-co-glycolic) and poly(ethylene glycol) nanoparticles for drug delivery using atomic force microscopy (AFM) and electrostatic nanolithography

    NASA Astrophysics Data System (ADS)

    Lyuksyutov, Sergei; Fedin, Igor; Nedashkivska, Victoria; Lyuksyutova, Caterina; Geldenhuys, Werner; Sutariya, Vijay

    2010-03-01

    Nanoparticles (NP) of biodegradable polymers poly(lactic-co-glycolic)(PLGA) and poly(ethylene glycol) (PEG) are potential drug delivery components for biomedical applications. The NP based on PLGA or PEG can be directed to accumulate in cancer tumor cells with the use of anti-bodies which are conjugated to the NP. The NP's size distribution is the critical property for biochemical affinity and therefore delivery to the specific target organs. We used an atomic force microscopy (AFM) to characterize the NP size and AFM electrostatic nanolithography (AFMEN) to study the behavior of PEG-PLGA NP under the extreme electric fields exceeding 10^9 V m-1. AFMEN allows the displacement of molecules along the lines of the electric field due to electrostatic polarization. This study has an important practical application for the optimum design of NP with the correct characteristics for drug delivery.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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)

  12. Atomic processes in high-density plasmas

    NASA Astrophysics Data System (ADS)

    More, R. M.

    Dense atomic plasmas such as that produced in inertial confinement fusion are reviewed. The target implosion physics along with the associated atomic physics, i.e., free electron collision phenomena, electron states I, electron states II, and nonequilibrum plasma states are described.

  13. Neutrino physics: Summary talk

    SciTech Connect

    Marciano, W.J.

    1989-04-01

    This paper is organized as follows: First, I describe the state of neutrino phenomenology. Emphasis is placed on sin/sup 2/ /theta//sub W/, its present status and future prospects. In addition, some signatures of ''new physics'' are described. Then, kaon physics at Fermilab is briefly discussed. I concentrate on the interesting rare decay K/sub L/ /yields/ /pi//sup 0/e/sup +/e/sup /minus// which may be a clean probe direct CP violation. Neutrino mass, mixing, and electromagnetic moments are surveyed. There, I describe the present state and future direction of accelerator based experiments. Finally, I conclude with an outlook on the future. Throughout this summary, I have drawn from and incorporated ideas discussed by other speakers at this workshop. However, I have tried to combine their ideas with my own perspective on neutrino physics and where it is headed. 49 refs., 3 figs., 4 tabs.

  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. SEMICONDUCTOR PHYSICS: Stability and vibrational properties of the hydrogen atom for p-type AlN doped with group-II: a first-principles study

    NASA Astrophysics Data System (ADS)

    Jianmin, Zhang; Guigui, Xu; Qingyun, Wu; Zhigao, Chen; Zhigao, Huang

    2010-06-01

    The stability and local vibrational mode (LVM) of hydrogen related p-type AlN have been studied by first-principles calculations based on density functional theory. The stable and metastable microscopic geometries of group-II (Be, Mg, Ca, Sr, Ba)-H complexes have been investigated. The calculated results indicate that BC|| is the most stable configuration for isolated interstitial H+ and Be-H complexes, while it is ABN,⊥ for Mg-H, Ca-H, Sr-H and Ba-H complexes. Moreover, the vibrational frequencies and the values of k and |α| for the H atom with LVM are calculated. Here, the values of k and |α| are used to describe the parameters of the harmonic and anharmonic contributions, respectively. The calculated results indicate that the larger the size of the doped ion is, the shorter the N-H bond length is, and the larger the potential energy, the vibrational frequencies, the values of k and |α| are. This implies that the size of the doped ion has an important influence on the vibrational properties of H.

  16. ATOMIC AND MOLECULAR PHYSICS: Mössbauer study of the field induced uniaxial anisotropy in electro-deposited FeCo alloy films

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Wei; Yang, Xu; Wang, Hai-Bo; Liu, Xin; Li, Fa-Shen

    2009-11-01

    Thin ferromagnetic films with in-plane magnetic anisotropy are promising materials for obtaining high microwave permeability. The paper reports a Mössbauer study of the field induced in-plane uniaxial anisotropy in electro-deposited FeCo alloy films. The FeCo alloy films were prepared by the electro-deposition method with and without an external magnetic field applied parallel to the film plane during deposition. Vibrating sample magnetometry and Mössbauer spectroscopy measurements at room temperature indicate that the film deposited in external field shows an in-plane uniaxial anisotropy with an easy direction coinciding with the external field direction and a hard direction perpendicular to the field direction, whereas the film deposited without external field does not show any in-plane anisotropy. Mössbauer spectra taken in three geometric arrangements show that the magnetic moments are almost constrained in the film plane for the film deposited with applied magnetic field. Also, the magnetic moments tend to align in the direction of the applied external magnetic field during deposition, indicating that the observed anisotropy should be attributed to directional ordering of atomic pairs.

  17. 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.

  18. Correlation of embryonic skeletal muscle myotube physical characteristics with contractile force generation on an atomic force microscope-based bio-microelectromechanical systems device.

    PubMed

    Pirozzi, K L; Long, C J; McAleer, C W; Smith, A S T; Hickman, J J

    2013-08-19

    Rigorous analysis of muscle function in in vitro systems is needed for both acute and chronic biomedical applications. Forces generated by skeletal myotubes on bio-microelectromechanical cantilevers were calculated using a modified version of Stoney's thin-film equation and finite element analysis (FEA), then analyzed for regression to physical parameters. The Stoney's equation results closely matched the more intensive FEA and the force correlated to cross-sectional area (CSA). Normalizing force to measured CSA significantly improved the statistical sensitivity and now allows for close comparison of in vitro data to in vivo measurements for applications in exercise physiology, robotics, and modeling neuromuscular diseases. PMID:24046483

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Observation of Atomic Antihydrogen

    SciTech Connect

    Blanford, G.; Gollwitzer, K.; Mandelkern, M.; Schultz, J.; Zioulas, G.; Christian, D.C.; Munger, C.T.

    1998-04-01

    We report the background-free observation of atomic antihydrogen, produced by interactions of an antiproton beam with a hydrogen gas jet target in the Fermilab Antiproton Accumulator. We measure the cross section of the reaction {ovr p}p{r_arrow}{ovr H}e{sup {minus}}p for {ovr p} beam momenta between 5203 and 6232 MeV/c to be 1.12{plus_minus}0.14{plus_minus}0.09 pb. {copyright} {ital 1998} {ital The American Physical Society}

  13. 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…

  14. Light element opacities from ATOMIC

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    We present new calculations of local-thermodynamic-equilibrium (LTE) light element opacities from the Los Alamos ATOMIC code. ATOMIC is a multi-purpose code that can generate LTE or non-LTE quantities of interest at various levels of approximation. A program of work is currently underway to compute new LTE opacity data for all elements H through Zn. New opacity tables for H through Ne are complete, and a new Fe opacity table will be available soon. Our calculations, which include fine-structure detail, represent a systematic improvement over previous Los Alamos opacity calculations using the LEDCOP legacy code. Our opacity calculations incorporate atomic structure data computed from the CATS code, which is based on Cowan's atomic structure codes, and photoionization cross section data computed from the Los Alamos ionization code GIPPER. We make use of a new equation-of-state (EOS) model based on the chemical picture. ATOMIC incorporates some physics packages from LEDCOP and also includes additional physical processes, such as improved free-free cross sections and additional scattering mechanisms. In this report, we briefly discuss the physics improvements included in our new opacity calculations and present comparisons of our new opacities with other work for C, O, and Fe at selected conditions.

  15. 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

  16. 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.

  17. Development of high intensity ion sources for a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

    PubMed

    Bergueiro, J; Igarzabal, M; Sandin, J C Suarez; Somacal, H R; Vento, V Thatar; Huck, H; Valda, A A; Repetto, M; Kreiner, A J

    2011-12-01

    Several ion sources have been developed and an ion source test stand has been mounted for the first stage of a Tandem-Electrostatic-Quadrupole facility For Accelerator-Based Boron Neutron Capture Therapy. A first source, designed, fabricated and tested is a dual chamber, filament driven and magnetically compressed volume plasma proton ion source. A 4 mA beam has been accelerated and transported into the suppressed Faraday cup. Extensive simulations of the sources have been performed using both 2D and 3D self-consistent codes.

  18. 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.

  19. 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)

  20. 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…

  1. 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…

  2. 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.

  3. 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.

  4. 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…

  5. Orientational atom interferometers sensitive to gravitational waves

    SciTech Connect

    Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas

    2010-02-15

    We present an atom interferometer that differs from common atom interferometers as it is not based on the spatial splitting of electronic wave functions, but on orienting atoms in space. As an example we present how an orientational atom interferometer based on highly charged hydrogen-like atoms is affected by gravitational waves. We show that a monochromatic gravitational wave will cause a frequency shift that scales with the binding energy of the system rather than with its physical dimension. For a gravitational wave amplitude of h=10{sup -23} the frequency shift is of the order of 110 {mu}Hz for an atom interferometer based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current atom interferometers in 1 s.

  6. 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.

  7. 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.

  8. 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.

  9. Quantum Physics

    NASA Astrophysics Data System (ADS)

    Le Bellac, Michel

    2006-03-01

    Quantum physics allows us to understand the nature of the physical phenomena which govern the behavior of solids, semi-conductors, lasers, atoms, nuclei, subnuclear particles and light. In Quantum Physics, Le Bellac provides a thoroughly modern approach to this fundamental theory. Throughout the book, Le Bellac teaches the fundamentals of quantum physics using an original approach which relies primarily on an algebraic treatment and on the systematic use of symmetry principles. In addition to the standard topics such as one-dimensional potentials, angular momentum and scattering theory, the reader is introduced to more recent developments at an early stage. These include a detailed account of entangled states and their applications, the optical Bloch equations, the theory of laser cooling and of magneto-optical traps, vacuum Rabi oscillations, and an introduction to open quantum systems. This is a textbook for a modern course on quantum physics, written for advanced undergraduate and graduate students. Completely original and contemporary approach, using algebra and symmetry principles Introduces recent developments at an early stage, including many topics that cannot be found in standard textbooks. Contains 130 physically relevant exercises

  10. The atomic orbitals of the topological atom.

    PubMed

    Ramos-Cordoba, Eloy; Salvador, Pedro; Mayer, István

    2013-06-01

    The effective atomic orbitals have been realized in the framework of Bader's atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure.

  11. "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…

  12. 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.

  13. Pathology of atomic bomb casualties.

    PubMed

    Iijima, S

    1982-01-01

    Thirty seven years ago, 6 August 1945 marks the date of the first atomic bombing never experienced in human history. It was dropped on Hiroshima and this was followed by a second bombing three days later on Nagasaki. The total deaths following exposure to the bomb by the end of 1945 totalled 140,000 (+/- 10,000) in Hiroshima and 70,000 (+/- 10,000) in Nagasaki. The present article described and outline of the physical effects of the atomic bomb and injury to the human body by exposure to the bomb.

  14. Nanolithography based on an atom pinhole camera.

    PubMed

    Melentiev, P N; Zablotskiy, A V; Lapshin, D A; Sheshin, E P; Baturin, A S; Balykin, V I

    2009-06-10

    In modern experimental physics the pinhole camera is used when the creation of a focusing element (lens) is difficult. We have experimentally realized a method of image construction in atom optics, based on the idea of an optical pinhole camera. With the use of an atom pinhole camera we have built an array of identical arbitrary-shaped atomic nanostructures with the minimum size of an individual nanostructure element down to 30 nm on an Si surface. The possibility of 30 nm lithography by means of atoms, molecules and clusters has been shown.

  15. 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%.

  16. 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,…

  17. 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.

  18. 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.

  19. 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.''

  20. Program system for three-dimensional coupled Monte Carlo-deterministic shielding analysis with application to the accelerator-based IFMIF neutron source

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Fischer, U.

    2005-10-01

    A program system for three-dimensional coupled Monte Carlo-deterministic shielding analysis has been developed to solve problems with complex geometry and bulk shield by integrating the Monte Carlo transport code MCNP, the three-dimensional discrete ordinates code TORT and a coupling interface program. A newly-proposed mapping approach is implemented in the interface program to calculate the angular flux distribution from the scored Monte Carlo particle tracks and generate the boundary source file for the use of TORT. Test calculations were performed with comparison to MCNP solutions. Satisfactory agreements were obtained between the results calculated by these two approaches. The program system has been chosen to treat the complicated shielding problem of the accelerator-based IFMIF neutron source. The successful application demonstrates that coupling scheme with the program system is a useful computational tool for the shielding analysis of complex and large nuclear facilities.

  1. 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.

  2. 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

  3. Inductively guided circuits for ultracold dressed atoms

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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, 7Li and 87Rb), 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.

  4. 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

  5. Atomic vapor laser isotope separation

    SciTech Connect

    Stern, R.C.; Paisner, J.A.

    1985-11-08

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

  6. '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

  7. 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.

  8. Mechanical gate control for atom-by-atom cluster assembly with scanning probe microscopy.

    PubMed

    Sugimoto, Yoshiaki; Yurtsever, Ayhan; Hirayama, Naoki; Abe, Masayuki; Morita, Seizo

    2014-07-11

    Nanoclusters supported on substrates are of great importance in physics and chemistry as well as in technical applications, such as single-electron transistors and nanocatalysts. The properties of nanoclusters differ significantly from those of either the constituent atoms or the bulk solid, and are highly sensitive to size and chemical composition. Here we propose a novel atom gating technique to assemble various atom clusters composed of a defined number of atoms at room temperature. The present gating operation is based on the transfer of single diffusing atoms among nanospaces governed by gates, which can be opened in response to the chemical interaction force with a scanning probe microscope tip. This method provides an alternative way to create pre-designed atom clusters with different chemical compositions and to evaluate their chemical stabilities, thus enabling investigation into the influence that a single dopant atom incorporated into the host clusters has on a given cluster stability.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Quantum computations with atoms in optical lattices: Marker qubits and molecular interactions

    SciTech Connect

    Calarco, T.; Dorner, U.; Zoller, P.; Julienne, P.S.; Williams, C.J.

    2004-07-01

    We develop a scheme for quantum computation with neutral atoms, based on the concept of 'marker' atoms, i.e., auxiliary atoms that can be efficiently transported in state-independent periodic external traps to operate quantum gates between physically distant qubits. This allows for relaxing a number of experimental constraints for quantum computation with neutral atoms in microscopic potential, including single-atom laser addressability. We discuss the advantages of this approach in a concrete physical scenario involving molecular interactions.

  14. 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

  15. 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

    2012-03-07

    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.

  16. 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.

  17. Scanning energy analyzer of charge exchange atoms

    SciTech Connect

    Rogozin, A.I.; Shikhovtsev, I.V.

    1994-12-31

    The construction, operation principle, and parameters of multichannel scanning energy analyzer of charge exchange atoms are discussed. The analyzer is used to measure the splashing ion angular distribution and energy spectra, the ions being produced in a gas dynamic plasma trap (GDCS) during the injection of powerful atomic hydrogen beam into preliminary produced plasma with density n {approx_equal} 5 {times} 10{sup 13} cm{sup {minus}3}. The parameters of the hydrogen beam are as follows: particle energy -50 keV, equivalent current -250 A, pulse duration -1 ms. The device can be also used for measurements of energy spectra of atomic and charged particle beams in plasma diagnostics, beam physics, and physics of atomic collisions. 4 refs., 4 figs.

  18. Atomic Fock states and quantum computing

    NASA Astrophysics Data System (ADS)

    Wan, Shoupu

    The potential impact of quantum computing has stimulated a world-wide effort to develop the necessary experimental and theoretical resources. In the race for the quantum computer, several candidate systems have emerged, but the ultimate system is still unclear. We study theoretically how to realize atomic Fock states both for fermionic and bosonic atoms, mainly in one-dimensional optical traps. We demonstrate a new approach of quantum computing based on ultracold fermionic atomic Fock states in optical traps. With the Pauli exclusion principle, producing fermionic atomic Fock states in optical traps is straightforward. We find that laser culling of fermionic atoms in optical traps can produce a scalable number of ultra-high fidelity qubits. We show how each qubit can be independently prepared, and how to perform the required entanglement operations and detect the qubit states with spatially resolved, single-atom detection with adiabatic trap-splitting and fluorescence imaging. On the other hand, bosonic atoms have a strong tendency to stay together. One must rely on strong repulsive interactions to produce bosonic atomic Fock states. To simulate the physical conditions of producing Fock states with ultracold bosonic atoms, we study a many-boson system with arbitrary interaction strength using the Bethe ansatz method. This approach provides a general framework, enabling the study of Fock state production over a wide range of realistic experimental parameters.

  19. 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,…

  20. 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…

  1. 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.

  2. Communication: An approximation to Bader's topological atom.

    PubMed

    Salvador, Pedro; Ramos-Cordoba, Eloy

    2013-08-21

    A new, more flexible definition of fuzzy Voronoi cells is proposed as a computationally efficient alternative to Bader's Quantum Theory of Atoms in Molecules (QTAIM) partitioning of the physical space for large-scale routine calculations. The new fuzzy scheme provides atomic charges, delocalization indices, and molecular energy components very close to those obtained using QTAIM. The method is flexible enough to either ignore the presence of spurious non-nuclear attractors or to readily incorporate them by introducing additional fuzzy Voronoi cells.

  3. Atomic clusters and atomic surfaces in icosahedral quasicrystals.

    PubMed

    Quiquandon, Marianne; Portier, Richard; Gratias, Denis

    2014-05-01

    This paper presents the basic tools commonly used to describe the atomic structures of quasicrystals with a specific focus on the icosahedral phases. After a brief recall of the main properties of quasiperiodic objects, two simple physical rules are discussed that lead one to eventually obtain a surprisingly small number of atomic structures as ideal quasiperiodic models for real quasicrystals. This is due to the fact that the atomic surfaces (ASs) used to describe all known icosahedral phases are located on high-symmetry special points in six-dimensional space. The first rule is maximizing the density using simple polyhedral ASs that leads to two possible sets of ASs according to the value of the six-dimensional lattice parameter A between 0.63 and 0.79 nm. The second rule is maximizing the number of complete orbits of high symmetry to construct as large as possible atomic clusters similar to those observed in complex intermetallic structures and approximant phases. The practical use of these two rules together is demonstrated on two typical examples of icosahedral phases, i-AlMnSi and i-CdRE (RE = Gd, Ho, Tm).

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. PHYSICAL BASIS OF QUANTUM ELECTRONICS: Inversion-free amplification of a probe field in a medium consisting of two-level degenerate atoms in the presence of a magnetic field

    NASA Astrophysics Data System (ADS)

    Konopleva, N. P.; Tumaikin, Anatolii M.

    1999-08-01

    The propagation of a probe field in a medium consisting of two-level atoms, degenerate in relation to the Jg = 1/2 → Je = 1/2 transition, is examined. The atoms are pumped by a circularly polarised resonant field in the presence of a static magnetic field. It is shown that under these conditions one of the normal waves may be amplified in the absence of inversion in the medium. In strong optical and magnetic fields, inversion-free amplification is possible for a pump with a finite spectral width, which may be much greater than the natural width of the excited level.

  11. 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

  12. 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.

  13. Rydberg atom interactions from 300 K to 300 K

    NASA Astrophysics Data System (ADS)

    Pillet, P.; Gallagher, T. F.

    2016-09-01

    Cold Rydberg atoms provide novel approaches to many-body problems and quantum simulation. To introduce the recent work presented in this special issue, we present here a quick history of a half-century research activity in the Rydberg-atom field, focusing our attention on the giant interactions between Rydberg atoms and other atoms. These interactions are the origin of many effects observed with Rydberg atoms: pressure shifts, dipole–dipole energy transfer, and avalanche-ionization. These effects have led to evidence of new bound chemical states, such as trilobites states, many-body effects in frozen Rydberg gases, and the spontaneous formation of ultra-cold plasmas. They open exciting new prospects at the intersection of atomic physics, condensed matter physics, and plasma physics.

  14. Rydberg atom interactions from 300 K to 300 K

    NASA Astrophysics Data System (ADS)

    Pillet, P.; Gallagher, T. F.

    2016-09-01

    Cold Rydberg atoms provide novel approaches to many-body problems and quantum simulation. To introduce the recent work presented in this special issue, we present here a quick history of a half-century research activity in the Rydberg-atom field, focusing our attention on the giant interactions between Rydberg atoms and other atoms. These interactions are the origin of many effects observed with Rydberg atoms: pressure shifts, dipole-dipole energy transfer, and avalanche-ionization. These effects have led to evidence of new bound chemical states, such as trilobites states, many-body effects in frozen Rydberg gases, and the spontaneous formation of ultra-cold plasmas. They open exciting new prospects at the intersection of atomic physics, condensed matter physics, and plasma physics.

  15. 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

  16. Laser Technology in Commercial Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Lutwak, R.

    2006-05-01

    Commercial atomic frequency standards (AFS) are deployed in diverse civilian, military, and aerospace applications, ranging from high-precision measurement and calibration to navigation, communications and, of course, timekeeping. Currently, commercially available AFS include magnetically-selected cesium beam frequency standards and hydrogen masers and lamp-pumped rubidium oscillators. Despite the revolution in atomic physics and laboratory-scale AFS brought about by the advent of the tunable laser in the early 1970s, commercial AFS invariably rely on more conventional atomic physics technology developed in the 1950s. The reason for this lack of advancement of commercial AFS technology is the relatively poor reliability and environmental sensitivity of narrow-linewidth single-mode laser sources at atomic resonance wavelengths. Over the past 8 years, Symmetricom, in collaboration with laser manufacturers, has developed specialized laser sources for commercial AFS applications. These laser devices, optimized for high spectral purity and long-term reliability, will enable a new generation of commercial AFS. This talk will briefly describe two laser-based atomic frequency standard development programs at Symmetricom. The Chip-Scale Atomic Clock, two orders of magnitude smaller and lower power than any commercial AFS, will enable atomic timing accuracy in portable battery-powered applications. The Optically-Pumped Cesium Beam Frequency Standard, under development for deployment onboard the GPS-III satellite constellation, will provide enhanced short-term stability and longer lifetime compared to magnetically-selected cesium beam AFS.

  17. 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)

  18. 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. )

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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/

  4. Atomizing nozzle and process

    DOEpatents

    Anderson, I.E.; Figliola, R.S.; Molnar, H.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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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….

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. Advances in atomic gyroscopes: a view from inertial navigation applications.

    PubMed

    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.

  16. 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

  17. 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

  18. 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.

  19. Materials selection for long life in low earth orbit - A critical evaluation of atomic oxygen testing with thermal atom systems

    NASA Technical Reports Server (NTRS)

    Koontz, S. L.; Albyn, K.; Leger, L.

    1990-01-01

    The use of thermal atom test methods as a materials selection and screening technique for low-earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative reactivities of a number of materials determined in thermal atom environments are compared with those observed in LEO and in high-quality LEO simulations. Reaction efficiencies (cu cm/atom) measured in a new type of thermal atom apparatus are one-thousandth to one ten-thousandth those observed in LEO, and many materials showing nearly identical reactivities in LEO show relative reactivities differing by as much as a factor of eight in thermal atom systems. A simple phenomenological kinetic model for the reaction of oxygen atoms with organic materials can be used to explain the differences in reactivity in different environments. Certain speciic thermal atom test environments can be used as reliable materials screening tools.

  20. 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.