Basic Course in Nucleonics. Technical Education Curriculum Development Series No. 10.

ERIC Educational Resources Information Center

Wiens, Jacob H.

This combined teaching and study guide is for use by students and teachers in post secondary programs for nucleonics technicians. It was developed by the author under the National Defense Education Act, Title VIII. The unit headings are: (1) Physics of the Atom, (2) Natural Radioactivity and Atomic Energy, (3) Induced Radioactivity and Atomic…

Plato's Ideas and the Theories of Modern Particle Physics: Amazing Parallels

NASA Astrophysics Data System (ADS)

Machleidt, Ruprecht

2006-05-01

It is generally known that the question, ``What are the most elementary particles that all matter is made from?'', was already posed in the antiquity. The Greek natural philosophers Leucippus and Democritus were the first to suggest that all matter was made from atoms. Therefore, most people perceive them as the ancient fathers of elementary particle physics. However, this perception is wrong. Modern particle physics is not just a simple atomism. The characteristic point of modern particle theory is that it is concerned with the symmetries underlying the particles we discover in experiment. More than 2000 years ago, a similar idea was already advanced by the Greek philosopher Plato in his dialogue Timaeus: Geometric symmetries generate the atoms from just a few even more elementary items. Plato's vision is amazingly close to the ideas of modern particle theory. This fact, which is unfortunately little known, has been pointed out repeatedly by Werner Heisenberg.

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

New contributions to physics by Prof. C. N. Yang: 2009-2011

NASA Astrophysics Data System (ADS)

Ma, Zhong-Qi

2016-01-01

In a seminal paper of 1967, Professor Chen Ning Yang found the full solution of the one-dimensional Fermi gas with a repulsive delta function interaction by using the Bethe ansatz and group theory. This work with a brilliant discovery of the Yang-Baxter equation has been inspiring new developments in mathematical physics, statistical physics, and many-body physics. Based on experimental developments in simulating many-body physics of one-dimensional systems of ultracold atoms, during a period from 2009 to 2011, Prof. Yang published seven papers on the exact properties of the ground state of bosonic and fermionic atoms with the repulsive delta function interaction and a confined potential to one dimension. Here I would like to share my experience in doing research work fortunately under the direct supervision of Prof. Yang in that period.

New Contributions to Physics by Prof. C. N. Yang: 2009-2011

NASA Astrophysics Data System (ADS)

Ma, Zhong-Qi

In a seminal paper of 1967, Professor Chen Ning Yang found the full solution of the one-dimensional Fermi gas with a repulsive delta function interaction by using the Bethe ansatz and group theory. This work with a brilliant discovery of the Yang-Baxter equation has been inspiring new developments in mathematical physics, statistical physics, and many-body physics. Based on experimental developments in simulating many-body physics of one-dimensional systems of ultracold atoms, during a period from 2009 to 2011, Prof. Yang published seven papers on the exact properties of the ground state of bosonic and fermionic atoms with the repulsive delta function interaction and a confined potential to one dimension. Here I would like to share my experience in doing research work fortunately under the direct supervision of Prof. Yang in that period.

Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

PubMed

Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

2011-11-01

A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission. © 2011 American Institute of Physics

Effects of cavity-cavity interaction on the entanglement dynamics of a generalized double Jaynes-Cummings model

NASA Astrophysics Data System (ADS)

Pandit, Mahasweta; Das, Sreetama; Singha Roy, Sudipto; Shekhar Dhar, Himadri; Sen, Ujjwal

2018-02-01

We consider a generalized double Jaynes-Cummings model consisting of two isolated two-level atoms, each contained in a lossless cavity that interact with each other through a controlled photon-hopping mechanism. We analytically show that at low values of such a mediated cavity-cavity interaction, the temporal evolution of entanglement between the atoms, under the effects of cavity perturbation, exhibits the well-known phenomenon of entanglement sudden death (ESD). Interestingly, for moderately large interaction values, a complete preclusion of ESD is achieved, irrespective of its value in the initial atomic state. Our results provide a model to sustain entanglement between two atomic qubits, under the adverse effect of cavity induced perturbation, by introducing a non-intrusive inter-cavity photon exchange that can be physically realized through cavity-QED setups in contemporary experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.

A dramatic symmetry breaking in K-shell photoionization of the CF 4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. In observing the photoejected electron in coincidence with an F + atomic ion after Auger decay we see how selecting the dissociation path where the core hole was localized was almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF 3 + and F + atoms elucidates themore » underlying physics that derives from the Ne-like valence structure of the F(1s -1) core-excited atom.« less

Proceedings of the 2003 NASA/JPL Workshop on Fundamental Physics in Space

NASA Technical Reports Server (NTRS)

Strayer, Don (Editor)

2003-01-01

The 2003 Fundamental Physics workshop included presentations ranging from forces acting on RNA to properties of clouds of degenerate Fermi atoms, to techniques to probe for a added space-time dimensions, and to flight hardware for low temperature experiments, amongst others. Mark Lee from NASA Headquarters described the new strategic plan that NASA has developed under Administrator Sean O'Keefe's leadership. Mark explained that the Fundamental Physics community now needs to align its research program and the roadmap describing the long-term goals of the program with the NASA plan. Ulf Israelsson of JPL discussed how the rewrite of the roadmap will be implemented under the leadership of the Fundamental Physics Discipline Working Group (DWG). Nick Bigelow, chair of the DWG, outlined how investigators can contribute to the writing of the roadmap. Results of measurements on very cold clouds of Fermi atoms near a Feshbach resonance were described by three investigators. Also, new measurements relating to tests of Einstein equivalence were discussed. Investigators also described methods to test other aspects of Einstein's relativity theories.

Entanglement dynamics in a Kerr spacetime

NASA Astrophysics Data System (ADS)

Menezes, G.

2018-04-01

We consider the entanglement dynamics between two-level atoms in a rotating black hole background. In our model the two-atom system is envisaged as an open system coupled with a massless scalar field prepared in one of the physical vacuum states of interest. We employ the quantum master equation in the Born-Markov approximation in order to describe the time evolution of the atomic subsystem. We investigate two different states of motion for the atoms, namely static atoms and also stationary atoms with zero angular momentum. The purpose of this work is to expound the impact on the creation of entanglement coming from the combined action of the different physical processes underlying the Hawking effect and the Unruh-Starobinskii effect. We demonstrate that, in the scenario of rotating black holes, the degree of quantum entanglement is significantly modified due to the phenomenon of superradiance in comparison with the analogous cases in a Schwarzschild spacetime. In the perspective of a zero angular momentum observer (ZAMO), one is allowed to probe entanglement dynamics inside the ergosphere, since static observers cannot exist within such a region. On the other hand, the presence of superradiant modes could be a source for violation of complete positivity. This is verified when the quantum field is prepared in the Frolov-Thorne vacuum state. In this exceptional situation, we raise the possibility that the loss of complete positivity is due to the breakdown of the Markovian approximation, which means that any arbitrary physically admissible initial state of the two atoms would not be capable to hold, with time evolution, its interpretation as a physical state inasmuch as negative probabilities are generated by the dynamical map.

Fundamental Physics with Antihydrogen

NASA Astrophysics Data System (ADS)

Hangst, J. S.

Antihydrogen—the antimatter equivalent of the hydrogen atom—is of fundamental interest as a test bed for universal symmetries—such as CPT and the Weak Equivalence Principle for gravitation. Invariance under CPT requires that hydrogen and antihydrogen have the same spectrum. Antimatter is of course intriguing because of the observed baryon asymmetry in the universe—currently unexplained by the Standard Model. At the CERN Antiproton Decelerator (AD) [1], several groups have been working diligently since 1999 to produce, trap, and study the structure and behaviour of the antihydrogen atom. One of the main thrusts of the AD experimental program is to apply precision techniques from atomic physics to the study of antimatter. Such experiments complement the high-energy searches for physics beyond the Standard Model. Antihydrogen is the only atom of antimatter to be produced in the laboratory. This is not so unfortunate, as its matter equivalent, hydrogen, is one of the most well-understood and accurately measured systems in all of physics. It is thus very compelling to undertake experimental examinations of the structure of antihydrogen. As experimental spectroscopy of antihydrogen has yet to begin in earnest, I will give here a brief introduction to some of the ion and atom trap developments necessary for synthesizing and trapping antihydrogen, so that it can be studied.

Positron Physics

NASA Technical Reports Server (NTRS)

Drachman, Richard J.

2003-01-01

I will give a review of the history of low-energy positron physics, experimental and theoretical, concentrating on the type of work pioneered by John Humberston and the positronics group at University College. This subject became a legitimate subfield of atomic physics under the enthusiastic direction of the late Sir Harrie Massey, and it attracted a diverse following throughout the world. At first purely theoretical, the subject has now expanded to include high brightness beams of low-energy positrons, positronium beams, and, lately, experiments involving anti-hydrogen atoms. The theory requires a certain type of persistence in its practitioners, as well as an eagerness to try new mathematical and numerical techniques. I will conclude with a short summary of some of the most interesting recent advances.

Superheavy Elements

ERIC Educational Resources Information Center

Tsang, Chin Fu

1975-01-01

Discusses the possibility of creating elements with an atomic number of around 114. Describes the underlying physics responsible for the limited extent of the periodic table and enumerates problems that must be overcome in creating a superheavy nucleus. (GS)

Neutral atom traps of rare isotopes

NASA Astrophysics Data System (ADS)

Mueller, Peter

2016-09-01

Laser cooling and trapping techniques offer exquisite control of an atom's external and internal degrees of freedom. The species of interest can be selectively captured, cooled close to absolute zero temperatures, and observed with high signal-to-noise ratio. Moreover, the atom's electronic and magnetic state populations can be precisely manipulated and interrogated. Applied in nuclear physics, these techniques are ideal for precision measurements in the fields of fundamental interactions and symmetries, nuclear structure studies, and isotopic trace analysis. In particular, they offer unique opportunities in the quest for physics beyond the standard model. I will shortly review the basics of this approach and the state of the field and then cover in more details recent results from two such efforts: the search for a permanent electric dipole moment in 225Ra and the beta-neutrino angular correlation measurement with laser trapped 6He. This work is supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.

Unambiguous observation of F-atom core-hole localization in CF 4 through body-frame photoelectron angular distributions

DOE PAGES

McCurdy, C. W.; Rescigno, T. N.; Trevisan, C. S.; ...

2017-01-17

A dramatic symmetry breaking in K-shell photoionization of the CF 4 molecule in which a core-hole vacancy is created in one of four equivalent fluorine atoms is displayed in the molecular frame angular distribution of the photoelectrons. In observing the photoejected electron in coincidence with an F + atomic ion after Auger decay we see how selecting the dissociation path where the core hole was localized was almost exclusively on that atom. A combination of measurements and ab initio calculations of the photoelectron angular distribution in the frame of the recoiling CF 3 + and F + atoms elucidates themore » underlying physics that derives from the Ne-like valence structure of the F(1s -1) core-excited atom.« less

New frontiers in quantum simulation enabled by precision laser spectroscopy

NASA Astrophysics Data System (ADS)

Rey, Ana M.

2014-05-01

Ultracold atomic systems have been proposed as ideal quantum simulators of real materials. Major breakthroughs have been achieved using neutral alkali atoms (one-outer-electron atoms) but their inherent ``simplicity'' introduces important limitations on the physics that can be investigated with them. Systems with more complex interactions and with richer internal structure offer an excellent platform for the exploration of a wider range of many-body phenomena. I will discuss our recent progress on the use of polar molecules, alkaline earth atoms -currently the basis of the most precise atomic clock in the world-, and trapped ions, as quantum simulators of iconic condensed matter Hamiltonians as well as Hamiltonians without solid state analogs. A promising direction under current exploration is the many-body physics that emerges at warmer temperatures (above quantum degeneracy) when there is a decoupling between motional and internal degrees of freedom. Even though in this regime the interaction energy scales can be small (~ Hz), they can be resolved thanks to the unprecedented level of control offered by modern precision laser spectroscopy. AFOSR, NSF, ARO and ARO-DARPA-OLE.

Atomic-scale analysis of cation ordering in reduced calcium titanate.

PubMed

Li, Luying; Hu, Xiaokang; Jiang, Fan; Jing, Wenkui; Guo, Cong; Jia, Shuangfeng; Gao, Yihua; Wang, Jianbo

2017-11-03

The phenomenon of cation ordering is closely related to certain physical properties of complex oxides, which necessitates the search of underlying structure-property relationship at atomic resolution. Here we study the superlattices within reduced calcium titanate single crystal micro-pillars, which are unexpected from the originally proposed atomic model. Bright and dark contrasts at alternating Ti double layers perpendicular to b axis are clearly observed, but show no signs in corresponding image simulations based on the proposed atomic model. The multi-dimensional chemical analyses at atomic resolution reveal periodic lower Ti concentrations at alternating Ti double layers perpendicular to b axis. The following in-situ heating experiment shows no phase transition at the reported T c and temperature independence of the superlattices. The dimerization of the Ti-Ti bonds at neighboring double rutile-type chains within Ti puckered sheets are directly observed, which is found to be not disturbed by the cation ordering at alternating Ti double layers. The characterization of cation ordering of complex oxides from chemical and structural point of view at atomic resolution, and its reaction to temperature variations are important for further understanding their basic physical properties and exploiting potential applications.

Atom Interferometry with Ultracold Quantum Gases in a Microgravity Environment

NASA Astrophysics Data System (ADS)

Williams, Jason; D'Incao, Jose; Chiow, Sheng-Wey; Yu, Nan

2015-05-01

Precision atom interferometers (AI) in space promise exciting technical capabilities for fundamental physics research, with proposals including unprecedented tests of the weak equivalence principle, precision measurements of the fine structure and gravitational constants, and detection of gravity waves and dark energy. Consequently, multiple AI-based missions have been proposed to NASA, including a dual-atomic-species interferometer that is to be integrated into the Cold Atom Laboratory (CAL) onboard the International Space Station. In this talk, I will discuss our plans and preparation at JPL for the proposed flight experiments to use the CAL facility to study the leading-order systematics expected to corrupt future high-precision measurements of fundamental physics with AIs in microgravity. The project centers on the physics of pairwise interactions and molecular dynamics in these quantum systems as a means to overcome uncontrolled shifts associated with the gravity gradient and few-particle collisions. We will further utilize the CAL AI for proof-of-principle tests of systematic mitigation and phase-readout techniques for use in the next-generation of precision metrology experiments based on AIs in microgravity. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

An ultracold potassium Rydberg source for experiments in quantum optics and many-body physics

NASA Astrophysics Data System (ADS)

Conover, Charles; Dupre, Pamela; Tong, Ai Phuong; Sanon, Carlvin; Clarke, Kevin; Doolittle, Brian; Louria, Stephen; Adamson, Philip

2017-04-01

We report on the development of an apparatus for the study of quantum dynamics of Rydberg atoms of potassium. Samples of Rydberg atoms at 1 mK and varying density are excited in a magneto-optical trap of 107 K-39 atoms. The atoms are excited to Rydberg states in a steps from 4s to 5p and from 5p to ns and nd states using stabilized external-cavity diode lasers at 405 nm and 980 nm. Selective field ionization and detection with microchannel plates provides a platform for spectroscopic measurements in potassium, exploration of multiphoton processes, and experiments on cold atom collisions. This research was supported by the National Science Foundation under Grant PHY-1126599.

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.

Synthetic dimensions for cold atoms from shaking a harmonic trap

NASA Astrophysics Data System (ADS)

Price, Hannah M.; Ozawa, Tomoki; Goldman, Nathan

2017-02-01

We introduce a simple scheme to implement synthetic dimensions in ultracold atomic gases, which only requires two basic and ubiquitous ingredients: the harmonic trap, which confines the atoms, combined with a periodic shaking. In our approach, standard harmonic oscillator eigenstates are reinterpreted as lattice sites along a synthetic dimension, while the coupling between these lattice sites is controlled by the applied time modulation. The phase of this modulation enters as a complex hopping phase, leading straightforwardly to an artificial magnetic field upon adding a second dimension. We show that this artificial gauge field has important consequences, such as the counterintuitive reduction of average energy under resonant driving, or the realization of quantum Hall physics. Our approach offers significant advantages over previous implementations of synthetic dimensions, providing an intriguing route towards higher-dimensional topological physics and strongly-correlated states.

Computational materials science: Think locally, act globally

NASA Astrophysics Data System (ADS)

Rabe, Karin M.

2002-11-01

New first-principles calculations reveal the range of atomic arrangements underlying the average crystallographic structure of a perovskite oxide, PZT. This work opens the door to understanding the exceptional physical behaviour of PZT and related systems.

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.

Theoretical prediction and atomic kinetic Monte Carlo simulations of void superlattice self-organization under irradiation.

PubMed

Gao, Yipeng; Zhang, Yongfeng; Schwen, Daniel; Jiang, Chao; Sun, Cheng; Gan, Jian; Bai, Xian-Ming

2018-04-26

Nano-structured superlattices may have novel physical properties and irradiation is a powerful mean to drive their self-organization. However, the formation mechanism of superlattice under irradiation is still open for debate. Here we use atomic kinetic Monte Carlo simulations in conjunction with a theoretical analysis to understand and predict the self-organization of nano-void superlattices under irradiation, which have been observed in various types of materials for more than 40 years but yet to be well understood. The superlattice is found to be a result of spontaneous precipitation of voids from the matrix, a process similar to phase separation in regular solid solution, with the symmetry dictated by anisotropic materials properties such as one-dimensional interstitial atom diffusion. This discovery challenges the widely accepted empirical rule of the coherency between the superlattice and host matrix crystal lattice. The atomic scale perspective has enabled a new theoretical analysis to successfully predict the superlattice parameters, which are in good agreement with independent experiments. The theory developed in this work can provide guidelines for designing target experiments to tailor desired microstructure under irradiation. It may also be generalized for situations beyond irradiation, such as spontaneous phase separation with reaction.

Composite pulses for interferometry in a thermal cold atom cloud

NASA Astrophysics Data System (ADS)

Dunning, Alexander; Gregory, Rachel; Bateman, James; Cooper, Nathan; Himsworth, Matthew; Jones, Jonathan A.; Freegarde, Tim

2014-09-01

Atom interferometric sensors and quantum information processors must maintain coherence while the evolving quantum wave function is split, transformed, and recombined, but suffer from experimental inhomogeneities and uncertainties in the speeds and paths of these operations. Several error-correction techniques have been proposed to isolate the variable of interest. Here we apply composite pulse methods to velocity-sensitive Raman state manipulation in a freely expanding thermal atom cloud. We compare several established pulse sequences, and follow the state evolution within them. The agreement between measurements and simple predictions shows the underlying coherence of the atom ensemble, and the inversion infidelity in a ˜80μK atom cloud is halved. Composite pulse techniques, especially if tailored for atom interferometric applications, should allow greater interferometer areas, larger atomic samples, and longer interaction times, and hence improve the sensitivity of quantum technologies from inertial sensing and clocks to quantum information processors and tests of fundamental physics.

Strategic Applications of Ultra-Cold Atoms

DTIC Science & Technology

2008-03-07

journals or in conference proceedings (N/A for none) 68.00Number of Papers published in peer-reviewed journals: Wolfgang Ketterle: New Frontiers with...Helmerson, V.S. Bagnato (American Institute of Physics, 2005) pp. 25-29. Wolfgang Ketterle: The Bose-Einstein Condensate- a Superfluid Gas of Coherent Atoms...Vuletic 0.10 No Wolfgang Ketterle 0.10 Yes David Pritchard 0.10 Yes Mara Prentiss 0.10 No 0.80FTE Equivalent: 8Total Number: Names of Under

Design of a Permanent-Magnet Zeeman Slower

NASA Astrophysics Data System (ADS)

Adler, Charles; Narducci, Frank; Sukenik, Charles; Mulholland, Jonathan; Goodale, Sarah

2006-05-01

During the past decade, low cost, flexible, and highly-polarized magnetic field sheet material has become available with field strengths useful for applications in modern atomic physics experiments. One advantage of using such material is that it can easily be cut to almost any desired shape without appreciable loss of field strength making it more versatile than ceramic magnets. We present the design of a Zeeman slower, made from such material, for cooling an atomic beam of neutral rubidium atoms and discuss results from an atomic beam trajectory simulation which indicates that the slower should perform well. We will also report on progress of a prototype permanent magnet Zeeman slower presently under construction in the laboratory.

Atom Interferometer Technologies in Space for Gravity Mapping and Gravity Science

NASA Astrophysics Data System (ADS)

Williams, Jason; Chiow, Sheng-Wey; Kellogg, James; Kohel, James; Yu, Nan

2015-05-01

Atom interferometers utilize the wave-nature of atomic gases for precision measurements of inertial forces, with potential applications ranging from gravity mapping for planetary science to unprecedented tests of fundamental physics with quantum gases. The high stability and sensitivity intrinsic to these devices already place them among the best terrestrial sensors available for measurements of gravitational accelerations, rotations, and gravity gradients, with the promise of several orders of magnitude improvement in their detection sensitivity in microgravity. Consequently, multiple precision atom-interferometer-based projects are under development at the Jet Propulsion Laboratory, including a dual-atomic-species interferometer that is to be integrated into the Cold Atom Laboratory onboard the International Space Station and a highly stable gravity gradiometer in a transportable design relevant for earth science measurements. We will present JPL's activities in the use of precision atom interferometry for gravity mapping and gravitational wave detection in space. Our recent progresses bringing the transportable JPL atom interferometer instrument to be competitive with the state of the art and simulations of the expected capabilities of a proposed flight project will also be discussed. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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

DOE PAGES

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

2016-08-12

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

Hydrogen atom in a quantum plasma environment under the influence of Aharonov-Bohm flux and electric and magnetic fields.

PubMed

Falaye, Babatunde James; Sun, Guo-Hua; Silva-Ortigoza, Ramón; Dong, Shi-Hai

2016-05-01

This study presents the confinement influences of Aharonov-Bohm (AB) flux and electric and magnetic fields directed along the z axis and encircled by quantum plasmas on the hydrogen atom. The all-inclusive effects result in a strongly attractive system while the localizations of quantum levels change and the eigenvalues decrease. We find that the combined effect of the fields is stronger than a solitary effect and consequently there is a substantial shift in the bound state energy of the system. We also find that to perpetuate a low-energy medium for the hydrogen atom in quantum plasmas, a strong electric field and weak magnetic field are required, whereas the AB flux field can be used as a regulator. The application of the perturbation technique utilized in this paper is not restricted to plasma physics; it can also be applied in molecular physics.

Nanoarchitectonics for Controlling the Number of Dopant Atoms in Solid Electrolyte Nanodots.

PubMed

Nayak, Alpana; Unayama, Satomi; Tai, Seishiro; Tsuruoka, Tohru; Waser, Rainer; Aono, Masakazu; Valov, Ilia; Hasegawa, Tsuyoshi

2018-02-01

Controlling movements of electrons and holes is the key task in developing today's highly sophisticated information society. As transistors reach their physical limits, the semiconductor industry is seeking the next alternative to sustain its economy and to unfold a new era of human civilization. In this context, a completely new information token, i.e., ions instead of electrons, is promising. The current trend in solid-state nanoionics for applications in energy storage, sensing, and brain-type information processing, requires the ability to control the properties of matter at the ultimate atomic scale. Here, a conceptually novel nanoarchitectonic strategy is proposed for controlling the number of dopant atoms in a solid electrolyte to obtain discrete electrical properties. Using α-Ag 2+ δ S nanodots with a finite number of nonstoichiometry excess dopants as a model system, a theory matched with experiments is presented that reveals the role of physical parameters, namely, the separation between electrochemical energy levels and the cohesive energy, underlying atomic-scale manipulation of dopants in nanodots. This strategy can be applied to different nanoscale materials as their properties strongly depend on the number of doping atoms/ions, and has the potential to create a new paradigm based on controlled single atom/ion transfer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the impact of high liquid viscosity on jet atomization in crossflow via high-fidelity simulations

NASA Astrophysics Data System (ADS)

Li, Xiaoyi; Gao, Hui; Soteriou, Marios C.

2017-08-01

Atomization of extremely high viscosity liquid can be of interest for many applications in aerospace, automotive, pharmaceutical, and food industries. While detailed atomization measurements usually face grand challenges, high-fidelity numerical simulations offer the advantage to comprehensively explore the atomization details. In this work, a previously validated high-fidelity first-principle simulation code HiMIST is utilized to simulate high-viscosity liquid jet atomization in crossflow. The code is used to perform a parametric study of the atomization process in a wide range of Ohnesorge numbers (Oh = 0.004-2) and Weber numbers (We = 10-160). Direct comparisons between the present study and previously published low-viscosity jet in crossflow results are performed. The effects of viscous damping and slowing on jet penetration, liquid surface instabilities, ligament formation/breakup, and subsequent droplet formation are investigated. Complex variations in near-field and far-field jet penetrations with increasing Oh at different We are observed and linked with the underlying jet deformation and breakup physics. Transition in breakup regimes and increase in droplet size with increasing Oh are observed, mostly consistent with the literature reports. The detailed simulations elucidate a distinctive edge-ligament-breakup dominated process with long surviving ligaments for the higher Oh cases, as opposed to a two-stage edge-stripping/column-fracture process for the lower Oh counterparts. The trend of decreasing column deflection with increasing We is reversed as Oh increases. A predominantly unimodal droplet size distribution is predicted at higher Oh, in contrast to the bimodal distribution at lower Oh. It has been found that both Rayleigh-Taylor and Kelvin-Helmholtz linear stability theories cannot be easily applied to interpret the distinct edge breakup process and further study of the underlying physics is needed.

Feshbach Prize: New Phenomena and New Physics from Strongly-Correlated Quantum Matter

NASA Astrophysics Data System (ADS)

Carlson, Joseph A.

2017-01-01

Strongly correlated quantum matter is ubiquitous in physics from cold atoms to nuclei to the cold dense matter found in neutron stars. Experiments from table-top to the extremely large scale experiments including FRIB and LIGO will help determine the properties of matter across an incredible scale of distances and energies. Questions to be addressed include the existence of exotic states of matter in cold atoms and nuclei, the response of this correlated matter to external probes, and the behavior of matter in extreme astrophysical environments. A more complete understanding is required, both to understand these diverse phenomena and to employ this understanding to probe for new underlying physics in experiments including neutrinoless double beta decay and accelerator neutrino experiments. I will summarize some aspects of our present understanding and highlight several important prospects for the future.

Operation of the computer model for direct atomic oxygen exposure of Earth satellites

NASA Technical Reports Server (NTRS)

Bourassa, R. J.; Gruenbaum, P. E.; Gillis, J. R.; Hargraves, C. R.

1995-01-01

One of the primary causes of material degradation in low Earth orbit (LEO) is exposure to atomic oxygen. When atomic oxygen molecules collide with an orbiting spacecraft, the relative velocity is 7 to 8 km/sec and the collision energy is 4 to 5 eV per atom. Under these conditions, atomic oxygen may initiate a number of chemical and physical reactions with exposed materials. These reactions contribute to material degradation, surface erosion, and contamination. Interpretation of these effects on materials and the design of space hardware to withstand on-orbit conditions requires quantitative knowledge of the atomic oxygen exposure environment. Atomic oxygen flux is a function of orbit altitude, the orientation of the orbit plan to the Sun, solar and geomagnetic activity, and the angle between exposed surfaces and the spacecraft heading. We have developed a computer model to predict the atomic oxygen exposure of spacecraft in low Earth orbit. The application of this computer model is discussed.

Mechanisms of boron fiber strengthening by thermal treatment

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1979-01-01

The fracture strain for boron on tungsten fibers can be improved by heat treatment under vacuum or argon environments. The mechanical basis for this improvement is thermally-induced axial contraction of the entire fiber, whereby strength-controlling core flaws are compressed and fiber fracture strain increased by the value of the contraction strain. By highly sensitive measurements of fiber density and volume, the physical mechanisms responsible for contraction under both environments was identified as boron atom diffusion out of the fiber sheath. The fiber contracts because the average volume of the resulting microvoid was determined to be only 0.26 + or - 0.09 the average atomic volume of the removed atom. The basic and practical implications of these results are discussed with particular emphasis on the theory, use, and limitations of heat-induced contraction as a simple cost-effective secondary processing method.

NLTE atomic kinetics modeling in ICF target simulations

NASA Astrophysics Data System (ADS)

Patel, Mehul V.; Mauche, Christopher W.; Scott, Howard A.; Jones, Ogden S.; Shields, Benjamin T.

2017-10-01

Radiation hydrodynamics (HYDRA) simulations using recently developed 1D spherical and 2D cylindrical hohlraum models have enabled a reassessment of the accuracy of energetics modeling across a range of NIF target configurations. Higher-resolution hohlraum calculations generally find that the X-ray drive discrepancies are greater than previously reported. We identify important physics sensitivities in the modeling of the NLTE wall plasma and highlight sensitivity variations between different hohlraum configurations (e.g. hohlraum gas fill). Additionally, 1D capsule only simulations show the importance of applying a similar level of rigor to NLTE capsule ablator modeling. Taken together, these results show how improved target performance predictions can be achieved by performing inline atomic kinetics using more complete models for the underlying atomic structure and transitions. Prepared by LLNL under Contract DE-AC52-07NA27344.

Theoretical modeling of laser-induced plasmas using the ATOMIC code

NASA Astrophysics Data System (ADS)

Colgan, James; Johns, Heather; Kilcrease, David; Judge, Elizabeth; Barefield, James, II; Clegg, Samuel; Hartig, Kyle

2014-10-01

We report on efforts to model the emission spectra generated from laser-induced breakdown spectroscopy (LIBS). LIBS is a popular and powerful method of quickly and accurately characterizing unknown samples in a remote manner. In particular, LIBS is utilized by the ChemCam instrument on the Mars Science Laboratory. We model the LIBS plasma using the Los Alamos suite of atomic physics codes. Since LIBS plasmas generally have temperatures of somewhere between 3000 K and 12000 K, the emission spectra typically result from the neutral and singly ionized stages of the target atoms. We use the Los Alamos atomic structure and collision codes to generate sets of atomic data and use the plasma kinetics code ATOMIC to perform LTE or non-LTE calculations that generate level populations and an emission spectrum for the element of interest. In this presentation we compare the emission spectrum from ATOMIC with an Fe LIBS laboratory-generated plasma as well as spectra from the ChemCam instrument. We also discuss various physics aspects of the modeling of LIBS plasmas that are necessary for accurate characterization of the plasma, such as multi-element target composition effects, radiation transport effects, and accurate line shape treatments. The Los Alamos National Laboratory is operated by Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC5206NA25396.

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

Ultracold few fermionic atoms in needle-shaped double wells: spin chains and resonating spin clusters from microscopic Hamiltonians emulated via antiferromagnetic Heisenberg and t-J models

NASA Astrophysics Data System (ADS)

Yannouleas, Constantine; Brandt, Benedikt B.; Landman, Uzi

2016-07-01

Advances with trapped ultracold atoms intensified interest in simulating complex physical phenomena, including quantum magnetism and transitions from itinerant to non-itinerant behavior. Here we show formation of antiferromagnetic ground states of few ultracold fermionic atoms in single and double well (DW) traps, through microscopic Hamiltonian exact diagonalization for two DW arrangements: (i) two linearly oriented one-dimensional, 1D, wells, and (ii) two coupled parallel wells, forming a trap of two-dimensional, 2D, nature. The spectra and spin-resolved conditional probabilities reveal for both cases, under strong repulsion, atomic spatial localization at extemporaneously created sites, forming quantum molecular magnetic structures with non-itinerant character. These findings usher future theoretical and experimental explorations into the highly correlated behavior of ultracold strongly repelling fermionic atoms in higher dimensions, beyond the fermionization physics that is strictly applicable only in the 1D case. The results for four atoms are well described with finite Heisenberg spin-chain and cluster models. The numerical simulations of three fermionic atoms in symmetric DWs reveal the emergent appearance of coupled resonating 2D Heisenberg clusters, whose emulation requires the use of a t-J-like model, akin to that used in investigations of high T c superconductivity. The highly entangled states discovered in the microscopic and model calculations of controllably detuned, asymmetric, DWs suggest three-cold-atom DW quantum computing qubits.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jong -Kyu

The 20th workshop on magnetohydrodynamic (MHD) stability control took place November 22–24, 2015, in Princeton Plasma Physics Laboratory (PPPL), following the American Physical Society—Division of Plasma Physics annual meeting on November 16–20 in Savannah, GA. The purpose of this workshop is to stimulate in depth discussion and motivate future research in the areas of MHD stability physics and control of magnetically confined plasmas. Furthermore, the workshop was organized jointly by Auburn University, Columbia University, General Atomics, Princeton Plasma Physics Laboratory, University of Wisconsin-Madison, and the Los Alamos National Laboratory, and under the auspices of the US/Japan Collaboration.

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.

Exotic objects of atomic physics

NASA Astrophysics Data System (ADS)

Eletskii, A. V.

2017-11-01

There has been presented a short survey of physical properties, methods of production and exploration as well as directions of practical usage of the objects of atomic physics which are not yet described in detail in modern textbooks and manuals intended for students of technical universities. The family of these objects includes negative and multicharged ions, Rydberg atoms, excimer molecules, clusters. Besides of that, in recent decades this family was supplemented with new nanocarbon structures such as fullerenes, carbon nanotubes and graphene. The textbook “Exotic objects of atomic physics” [1] edited recently contains some information on the above-listed objects of the atomic physics. This textbook can be considered as a supplement to classic courses of atomic physics teaching in technical universities.

Plato's TIMAIOσ (TIMAEUS) and Modern Particle Physics

NASA Astrophysics Data System (ADS)

Machleidt, Ruprecht

2005-04-01

It is generally known that the question, ``What are the smallest particles (elementary particles) that all matter is made from?'', was posed already in the antiquity. The Greek natural philosophers Leucippus and Democritus were the first to suggest that all matter was made from atoms. Therefore, most people perceive them as the ancient fathers of elementary particle physics. It will be the purpose of my contribution to point out that this perception is wrong. Modern particle physics is not just a primitive atomism. More important than the materialistic particles are the underlying symmetries (e. g., SU(3) and SU(6)). A similar idea was first advanced by Plato in his dialog TIMAIOσ (Latin translation: TIMAEUS): Geometric symmetries generate the materialistic particles from a few even more elementary items. Plato's vision is amazingly close to the ideas of modern particle physics. This fact, which is unfortunately little known, has been pointed out repeatedly by Heisenberg (see, e. g., Werner Heisenberg, Across the Frontiers, Harper & Row, New York, 1974).

(Proceedings) 18th Advanced ICFA Beam Dynamics Workshop on Quantum Aspects of Beam Physics (QABP)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Pisin

2002-10-25

The 18th Advanced ICFA Beam Dynamics Workshop on ''Quantum Aspects of Beam Physics'' was held from October 15 to 20, 2000, in Capri, Italy. This was the second workshop under the same title. The first one was held in Monterey, California, in January, 1998. Following the footstep of the first meeting, the second one in Capri was again a tremendous success, both scientifically and socially. About 70 colleagues from astrophysics, atomic physics, beam physics, condensed matter physics, particle physics, and general relativity gathered to update and further explore the topics covered in the Monterey workshop. Namely, the following topics weremore » actively discussed: (1) Quantum Fluctuations in Beam Dynamics; (2) Photon-Electron Interaction in Beam handling; (3) Physics of Condensed Beams; (4) Beam Phenomena under Strong Fields; (5) Quantum Methodologies in Beam Physics. In addition, there was a newly introduced subject on Astro-Beam Physics and Laboratory Astrophysics.« less

Mechanisms of boron fiber strengthening by thermal treatment

NASA Technical Reports Server (NTRS)

Dicarlo, J. A.

1979-01-01

The fracture strain for boron on tungsten fibers was studied for improvement by heat treatment under vacuum or argon environments. The mechanical basis for this improvement is thermally-induced axial contraction of the entire fiber, whereby strength-controlling core flaws are compressed and fiber fracture strain increased by the value of the contraction strain. By highly sensitive measurements of fiber density and volume, the physical mechanism responsible for contraction under both environments was identified as boron atom diffusion out of the fiber sheath. The fiber contracts because the average volume of the resulting microvoid was determined to be only 0.26 plus or minus 0.09 the average atomic volume of the removed atom. The basic and practical implications of these results are discussed with particular emphasis on the theory, use, and limitations of heat-induced contraction as a simple cost-effective secondary processing method.

The Design, Fabrication and Characterization of a Transparent Atom Chip

PubMed Central

Chuang, Ho-Chiao; Huang, Chia-Shiuan; Chen, Hung-Pin; Huang, Chi-Sheng; Lin, Yu-Hsin

2014-01-01

This study describes the design and fabrication of transparent atom chips for atomic physics experiments. A fabrication process was developed to define the wire patterns on a transparent glass substrate to create the desired magnetic field for atom trapping experiments. An area on the chip was reserved for the optical access, so that the laser light can penetrate directly through the glass substrate for the laser cooling process. Furthermore, since the thermal conductivity of the glass substrate is poorer than other common materials for atom chip substrate, for example silicon, silicon carbide, aluminum nitride. Thus, heat dissipation copper blocks are designed on the front and back of the glass substrate to improve the electrical current conduction. The testing results showed that a maximum burnout current of 2 A was measured from the wire pattern (with a width of 100 μm and a height of 20 μm) without any heat dissipation design and it can increase to 2.5 A with a heat dissipation design on the front side of the atom chips. Therefore, heat dissipation copper blocks were designed and fabricated on the back of the glass substrate just under the wire patterns which increases the maximum burnout current to 4.5 A. Moreover, a maximum burnout current of 6 A was achieved when the entire backside glass substrate was recessed and a thicker copper block was electroplated, which meets most requirements of atomic physics experiments. PMID:24922456

Prospects of Optical Single Atom Detection in Noble Gas Solids for Measurements of Rare Nuclear Reactions

NASA Astrophysics Data System (ADS)

Singh, Jaideep; Bailey, Kevin G.; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Thomas P.; Xu, Chen-Yu; Tang, Xiaodong

2013-04-01

Optical detection of single atoms captured in solid noble gas matrices provides an alternative technique to study rare nuclear reactions relevant to nuclear astrophysics. I will describe the prospects of applying this approach for cross section measurements of the ^22Ne,,),25Mg reaction, which is the crucial neutron source for the weak s process inside of massive stars. Noble gas solids are a promising medium for the capture, detection, and manipulation of atoms and nuclear spins. They provide stable and chemically inert confinement for a wide variety of guest species. Because noble gas solids are transparent at optical wavelengths, the guest atoms can be probed using lasers. We have observed that ytterbium in solid neon exhibits intersystem crossing (ISC) which results in a strong green fluorescence (546 nm) under excitation with blue light (389 nm). Several groups have observed ISC in many other guest-host pairs, notably magnesium in krypton. Because of the large wavelength separation of the excitation light and fluorescence light, optical detection of individual embedded guest atoms is feasible. This work is supported by DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

Learning molecular energies using localized graph kernels.

PubMed

Ferré, Grégoire; Haut, Terry; Barros, Kipton

2017-03-21

Recent machine learning methods make it possible to model potential energy of atomic configurations with chemical-level accuracy (as calculated from ab initio calculations) and at speeds suitable for molecular dynamics simulation. Best performance is achieved when the known physical constraints are encoded in the machine learning models. For example, the atomic energy is invariant under global translations and rotations; it is also invariant to permutations of same-species atoms. Although simple to state, these symmetries are complicated to encode into machine learning algorithms. In this paper, we present a machine learning approach based on graph theory that naturally incorporates translation, rotation, and permutation symmetries. Specifically, we use a random walk graph kernel to measure the similarity of two adjacency matrices, each of which represents a local atomic environment. This Graph Approximated Energy (GRAPE) approach is flexible and admits many possible extensions. We benchmark a simple version of GRAPE by predicting atomization energies on a standard dataset of organic molecules.

Learning molecular energies using localized graph kernels

NASA Astrophysics Data System (ADS)

Ferré, Grégoire; Haut, Terry; Barros, Kipton

2017-03-01

Recent machine learning methods make it possible to model potential energy of atomic configurations with chemical-level accuracy (as calculated from ab initio calculations) and at speeds suitable for molecular dynamics simulation. Best performance is achieved when the known physical constraints are encoded in the machine learning models. For example, the atomic energy is invariant under global translations and rotations; it is also invariant to permutations of same-species atoms. Although simple to state, these symmetries are complicated to encode into machine learning algorithms. In this paper, we present a machine learning approach based on graph theory that naturally incorporates translation, rotation, and permutation symmetries. Specifically, we use a random walk graph kernel to measure the similarity of two adjacency matrices, each of which represents a local atomic environment. This Graph Approximated Energy (GRAPE) approach is flexible and admits many possible extensions. We benchmark a simple version of GRAPE by predicting atomization energies on a standard dataset of organic molecules.

Forbidden atomic transitions driven by an intensity-modulated laser trap.

PubMed

Moore, Kaitlin R; Anderson, Sarah E; Raithel, Georg

2015-01-20

Spectroscopy is an essential tool in understanding and manipulating quantum systems, such as atoms and molecules. The model describing spectroscopy includes the multipole-field interaction, which leads to established spectroscopic selection rules, and an interaction that is quadratic in the field, which is not often employed. However, spectroscopy using the quadratic (ponderomotive) interaction promises two significant advantages over spectroscopy using the multipole-field interaction: flexible transition rules and vastly improved spatial addressability of the quantum system. Here we demonstrate ponderomotive spectroscopy by using optical-lattice-trapped Rydberg atoms, pulsating the lattice light and driving a microwave atomic transition that would otherwise be forbidden by established spectroscopic selection rules. This ability to measure frequencies of previously inaccessible transitions makes possible improved determinations of atomic characteristics and constants underlying physics. The spatial resolution of ponderomotive spectroscopy is orders of magnitude better than the transition frequency would suggest, promising single-site addressability in dense particle arrays for quantum computing applications.

Special Issue on the 20th Workshop on MHD Stability Control

DOE PAGES

Park, Jong -Kyu

2016-11-08

The 20th workshop on magnetohydrodynamic (MHD) stability control took place November 22–24, 2015, in Princeton Plasma Physics Laboratory (PPPL), following the American Physical Society—Division of Plasma Physics annual meeting on November 16–20 in Savannah, GA. The purpose of this workshop is to stimulate in depth discussion and motivate future research in the areas of MHD stability physics and control of magnetically confined plasmas. Furthermore, the workshop was organized jointly by Auburn University, Columbia University, General Atomics, Princeton Plasma Physics Laboratory, University of Wisconsin-Madison, and the Los Alamos National Laboratory, and under the auspices of the US/Japan Collaboration.

Structural and elastic properties and stability characteristics of oxygenated carbon nanotubes under physical adsorption of polymers

NASA Astrophysics Data System (ADS)

Ansari, R.; Ajori, S.; Rouhi, S.

2015-03-01

The importance of covalent and non-covalent functionalization approaches for modification the properties of carbon nanotubes is being more widely recognized. To this end, elastic properties and buckling behavior of oxygenated CNT with atomic oxygen and hydroxyl under physical adsorption of PE (Polyethylene) and PEO (Poly (ethylene oxide)) are determined through employing the molecular dynamics (MD) simulations. The results demonstrate that non-covalent bonding of polymer on the surface of oxygenated CNT causes reductions in the variations of critical buckling load and critical strain compared to oxygenated CNTs. Critical buckling load and critical strain of oxygenated CNT/polymer are higher than those of oxygenated CNT. Also, it is demonstrated that critical buckling load and critical strain values in the case of oxygenated CNT/polymer are independent of polymer type unlike the value of Young's modulus. It is shown that variations of Young's modulus decrease as PE adsorbed on the surface of oxygenated CNT. Moreover, the presence of oxygen atom on PEO chain leads to bigger variations of Young's modulus with weight percentage of chemisorbed component, i.e. atomic oxygen and hydroxyl. It is also demonstrated that Young's modulus reduces more considerably in the presence of PEO chain compared to PE one.

Atomic force microscopy of atomic-scale ledges and etch pits formed during dissolution of quartz

NASA Technical Reports Server (NTRS)

Gratz, A. J.; Manne, S.; Hansma, P. K.

1991-01-01

The processes involved in the dissolution and growth of crystals are closely related. Atomic force microscopy (AFM) of faceted pits (called negative crystals) formed during quartz dissolution reveals subtle details of these underlying physical mechanisms for silicates. In imaging these surfaces, the AFM detected ledges less than 1 nm high that were spaced 10 to 90 nm apart. A dislocation pit, invisible to optical and scanning electron microscopy measurements and serving as a ledge source, was also imaged. These observations confirm the applicability of ledge-motion models to dissolution and growth of silicates; coupled with measurements of dissolution rate on facets, these methods provide a powerful tool for probing mineral surface kinetics.

Investigation of ZPE and temperature effects on the Eley-Rideal recombination of hydrogen atoms on graphene using a multidimensional graphene-H-H potential

NASA Astrophysics Data System (ADS)

Sizun, M.; Bachellerie, D.; Aguillon, F.; Sidis, V.

2010-09-01

We study the Eley-Rideal recombination of H atoms on graphene under the physical conditions of the interstellar medium. Effects of the ZPE motions of the chemisorbed H atom and of the graphene thermal motions are investigated. Classical molecular dynamics calculations undertaken with the multidimensional potential of Bachellerie et al. [Phys. Chem. Chem. Phys. 11 (2009) 2715] are reported. The ZPE effects are the strongest. The closer the collision energy is to the classical reaction threshold the more sizeable the effects. The quantum reaction cross section is also estimated below and above the classical threshold using a capture model.

Valley filters, accumulators, and switches induced in graphene quantum dots by lines of adsorbed hydrogen atoms

NASA Astrophysics Data System (ADS)

Azari, Mohammadhadi; Kirczenow, George

2018-06-01

We present electronic structure and quantum transport calculations that predict conducting channels induced in graphene quantum dots by lines of adsorbed hydrogen atoms to function as highly efficient, experimentally realizable valley filters, accumulators, and switches. The underlying physics is an interesting property of graphene Dirac point resonances (DPRs) that is revealed here, namely, that an electric current passing through a DPR-mediated conducting channel in a given direction is carried by electrons of only one of the two graphene valleys. Our predictions apply to lines of hydrogen atoms adsorbed on graphene quantum dots that are either free standing or supported on a hexagonal boron nitride substrate.

Cold Atom Optics on Ground and in Space

NASA Astrophysics Data System (ADS)

Rasel, E. M.

Microgravity is the ultimate laboratory environment for experiments in fundamental physics based on cold atoms. The talk will give a survey of recent activities on atomic quantum sensors and atom lasers. Inertial atomic quantum sensors are a promising and complementary technique for experiments in fundamental physics. Pioneering experiments at Yale [1,2] and Stanford [3] displayed recently the fascinating potential of matter-wave interferometers for precision measurements. The talk will present the status of a transportable matter-wave sensor under development at the Institut für Quantenoptik in Hannover: CASI. CASI stands for Cold Atom Sagnac Interferometer. The use of cold atoms makes it possible to realise compact devices with sensitivities competitive with classical state-of-the-art sensors. CASI's projected sensitivity is about 10-9 rad/ssurd Hz at the projection noise limit. The heart of our set-up will be a 15cm-long Mach-Zehnder interferometer formed by coherently splitting the atoms with Raman-type interactions. CASI is designed as a movable device, that it can be compared with other matter-wave sensors such as the cold caesium atom gyroscope at the BNM-SYRTE in Paris [4]. CASI is intimately connected with HYPER, an European initiative to send four atom interferometers in space hosted on a drag-free satellite. Main emphasis of the mission is placed on the mapping of the Earth's Lense-Thirring effect. Tests of the Equivalence Principle is under consideration as an alternative goal of high scientific value. HYPER was selected three years ago by the European Space Agency (ESA) as candidate for a future small-satellite mission within the next 10 to 15 years and is supported with detailed feasibility studies [5]. The latest status of the mission will be given. [1] T.L. Gustavson, A. Landragin, M.A, Kasevich, Rotation sensing with a dual atom-interferometer Sagnac gyroscope, Class. Quantum Grav. 17, 2385-2398 (2000) [2] J.M. McGuirk, G.T. Foster, J.B. Fixler, M.J. Snadden, M.A. Kasevich, Sensitive absolute-gravity gradiometry using atom interferometry, Phys. Rev. A 65, 033608-1 (2002) [3] A. Peters, K.Y. Chung, S. Chu, High-precision gravity measurements using atom interferometry, Metrologia 38, 25-61 (2001) [4] F. Yver-Leduc, P. Cheinet, J. Fils, A. Clairon, N. Dimarcq, D. Holleville, P. Bouyer, and A. Landragin. A. J. Opt. B : Quant. Semiclass. Opt. 5, S136 (2003) [5] http://sci.esa.int/home/hyper/index.cfm

Characterization, performance and optimization of PVDF as a piezoelectric film for advanced space mirror concepts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, Gary D.; Assink, Roger Alan; Dargaville, Tim Richard

2005-11-01

Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes as adaptive or smart materials. Dimensional adjustments of adaptive polymer films depend on controlled charge deposition. Predicting their long-term performance requires a detailed understanding of the piezoelectric material features, expected to suffer due to space environmental degradation. Hence, the degradation and performance of PVDF and its copolymers under various stress environments expected in low Earth orbit has been reviewed and investigated. Various experiments were conducted to expose these polymers to elevated temperature, vacuum UV, {gamma}-radiation and atomic oxygen. The resulting degradative processes were evaluated. Themore » overall materials performance is governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and atomic oxygen exposure is evident as depoling, loss of orientation and surface erosion. The effects of combined vacuum UV radiation and atomic oxygen resulted in expected surface erosion and pitting rates that determine the lifetime of thin films. Interestingly, the piezo responsiveness in the underlying bulk material remained largely unchanged. This study has delivered a comprehensive framework for material properties and degradation sensitivities with variations in individual polymer performances clearly apparent. The results provide guidance for material selection, qualification, optimization strategies, feedback for manufacturing and processing, or alternative materials. Further material qualification should be conducted via experiments under actual space conditions.« less

Correlation between the band gap expansion and melting temperature depression of nanostructured semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jianwei, E-mail: jwl189@163.com; Zhao, Xinsheng; Liu, Xinjuan

The band gap and melting temperature of a semiconductor are tunable with the size and shape of the specimen at the nanometer scale, and related mechanisms remain as yet unclear. In order to understand the common origin of the size and shape effect on these two seemingly irrelevant properties, we clarify, correlate, formulate, and quantify these two properties of GaAs, GaN, InP, and InN nanocrystals from the perspectives of bond order-length-strength correlation using the core-shell configuration. The consistency in the theoretical predictions, experimental observations, and numerical calculations verify that the broken-bond-induced local bond contraction and strength gain dictates the bandmore » gap expansion, while the atomic cohesive energy loss due to bond number reduction depresses the melting point. The fraction of the under-coordinated atoms in the skin shell quantitatively determines the shape and size dependency. The atomic under-coordination in the skin down to a depth of two atomic layers inducing a change in the local chemical bond is the common physical origin.« less

Compact atom interferometer using single laser

NASA Astrophysics Data System (ADS)

Chiow, Sheng-Wey; Yu, Nan

2017-04-01

Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. The complexity of required laser system and the size of vacuum chamber driven by optical access requirement limit the applicability of such technology in size, weight, and power (SWaP) challenging environments, such as in space. For instance, a typical physics package of AI includes six viewports for laser cooling and trapping, two for AI beams, and two more for detection and a vacuum pump. Similarly, a typical laser system for an AI includes two lasers for cooling and repumping, and two for Raman transitions as AI beam splitters. In this presentation, we report our efforts in developing a miniaturized atomic accelerometer for planetary exploration. We will describe a physics package configuration having minimum optical access (thus small volume), and a laser and optics system utilizing a single laser for the sensor operation. Preliminary results on acceleration sensitivity will be discussed. We will also illustrate a path for further packaging and integration based on the demonstrated concepts. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Understanding electron magnetic circular dichroism in a transition potential approach

NASA Astrophysics Data System (ADS)

Barthel, J.; Mayer, J.; Rusz, J.; Ho, P.-L.; Zhong, X. Y.; Lentzen, M.; Dunin-Borkowski, R. E.; Urban, K. W.; Brown, H. G.; Findlay, S. D.; Allen, L. J.

2018-04-01

This paper introduces an approach based on transition potentials for inelastic scattering to understand the underlying physics of electron magnetic circular dichroism (EMCD). The transition potentials are sufficiently localized to permit atomic-scale EMCD. Two-beam and three-beam systematic row cases are discussed in detail in terms of transition potentials for conventional transmission electron microscopy, and the basic symmetries which arise in the three-beam case are confirmed experimentally. Atomic-scale EMCD in scanning transmission electron microscopy (STEM), using both a standard STEM probe and vortex beams, is discussed.

EDITORIAL: The 15th Central European Workshop on Quantum Optics The 15th Central European Workshop on Quantum Optics

NASA Astrophysics Data System (ADS)

Bozic, Mirjana; Man'ko, Margarita; Arsenovic, Dusan

2009-07-01

The development of quantum optics was part and parcel of the formation of modern physics following the fundamental work of Max Planck and Albert Einstein, which gave rise to quantum mechanics. The possibility of working with pure quantum objects, like single atoms and single photons, has turned quantum optics into the main tool for testing the fundamentals of quantum physics. Thus, despite a long history, quantum optics nowadays remains an extremely important branch of physics. It represents a natural base for the development of advanced technologies, like quantum information processing and quantum computing. Previous Central European Workshops on Quantum Optics (CEWQO) took place in Palermo (2007), Vienna (2006), Ankara (2005), Trieste (2004), Rostock (2003), Szeged (2002), Prague (2001), Balatonfüred (2000), Olomouc (1999), Prague (1997), Budmerice (1995, 1996), Budapest (1994) and Bratislava (1993). Those meetings offered excellent opportunities for the exchange of knowledge and ideas between leading scientists and young researchers in quantum optics, foundations of quantum mechanics, cavity quantum electrodynamics, photonics, atom optics, condensed matter optics, and quantum informatics, etc. The collaborative spirit and tradition of CEWQO were a great inspiration and help to the Institute of Physics, Belgrade, and the Serbian Academy of Sciences and Arts, as the organizers of CEWQO 2008. The 16th CEWQO will take place in 2009 in Turku, Finland, and the 17th CEWQO will be organized in 2010 in St Andrews, United Kingdom. The 15th CEWQO was organized under the auspices and support of the Ministry of Science of the Republic of Serbia, the Serbian Physical Society, the European Physical Society with sponsorship from the University of Belgrade, the Central European Initiative, the FP6 Program of the European Commission under INCO project QUPOM No 026322, the FP7 Program of the European Commission under project NANOCHARM, Europhysics Letters (EPL), The European Physical Journal (EPJ), and John Wiley and Sons.

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.

Dynamics of entanglement of a three-level atom in motion interacting with two coupled modes including parametric down conversion

NASA Astrophysics Data System (ADS)

Faghihi, M. J.; Tavassoly, M. K.; Hatami, M.

In this paper, a model by which we study the interaction between a motional three-level atom and two-mode field injected simultaneously in a bichromatic cavity is considered; the three-level atom is assumed to be in a Λ-type configuration. As a result, the atom-field and the field-field interaction (parametric down conversion) will be appeared. It is shown that, by applying a canonical transformation, the introduced model can be reduced to a well-known form of the generalized Jaynes-Cummings model. Under particular initial conditions, which may be prepared for the atom and the field, the time evolution of state vector of the entire system is analytically evaluated. Then, the dynamics of atom by considering ‘atomic population inversion’ and two different measures of entanglement, i.e., ‘von Neumann entropy’ and ‘idempotency defect’ is discussed, in detail. It is deduced from the numerical results that, the duration and the maximum amount of the considered physical quantities can be suitably tuned by selecting the proper field-mode structure parameter p and the detuning parameters.

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

Compact Single Site Resolution Cold Atom Experiment for Adiabatic Quantum Computing

DTIC Science & Technology

2016-02-03

goal of our scientific investigation is to demonstrate high fidelity and fast atom-atom entanglement between physically 1. REPORT DATE (DD-MM-YYYY) 4...of our scientific investigation is to demonstrate high fidelity and fast atom-atom entanglement between physically separated and optically addressed...Specifically, we will design and construct a set of compact single atom traps with integrated optics, suitable for heralded entanglement and loophole

STIR-Physics: Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials

DTIC Science & Technology

2016-11-02

STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber and High-Q Resonator Potentials We worked on a tapered fiber in cold atomic cloud...reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: STIR- Physics : Cold Atoms and Nanocrystals in Tapered Nanofiber...other than abstracts): Number of Peer-Reviewed Conference Proceeding publications (other than abstracts): Books Number of Manuscripts: 0.00Number of

Steering Quantum States Towards Classical Bohr-Like Orbits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunning, F. B.; Reinhold, Carlos O; Yoshida, S.

2010-01-01

This article furnishes an introduction to the properties of time-dependent electronic wavefunctions in atoms and to physics at the interface between the quantum and classical worlds. We describe how, almost 100 years after the introduction of the Bohr model of the atom, it is now possible using pulsed electric fields to create in the laboratory localized wavepackets in high-n (n ~ 300) Rydberg atoms that travel in near-circular Bohr-like orbits mimicking the behavior of a classical electron. The control protocols employed are explained with the aid of quantum and classical dynamics. Remarkably, while many aspects of the underlying behavior canmore » be described using classical arguments, even at n ~ 300 purely quantum effects such as revivals can be seen.« less

Anomalous evolution of Ar metastable density with electron density in high density Ar discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Min; Chang, Hong-Young; You, Shin-Jae

2011-10-15

Recently, an anomalous evolution of argon metastable density with plasma discharge power (electron density) was reported [A. M. Daltrini, S. A. Moshkalev, T. J. Morgan, R. B. Piejak, and W. G. Graham, Appl. Phys. Lett. 92, 061504 (2008)]. Although the importance of the metastable atom and its density has been reported in a lot of literature, however, a basic physics behind the anomalous evolution of metastable density has not been clearly understood yet. In this study, we investigated a simple global model to elucidate the underlying physics of the anomalous evolution of argon metastable density with the electron density. Onmore » the basis of the proposed simple model, we reproduced the anomalous evolution of the metastable density and disclosed the detailed physics for the anomalous result. Drastic changes of dominant mechanisms for the population and depopulation processes of Ar metastable atoms with electron density, which take place even in relatively low electron density regime, is the clue to understand the result.« less

The Scientific Legacy of Ugo Fano

NASA Astrophysics Data System (ADS)

Inokuti, Mitio

2001-04-01

In 1934 Fano received a Sc. D. degree in mathematics at University of Turin, Italy (the city of his birth in 1912). He was then led to physics by his cousin Guilio Racah, and received postdoctoral training from Fermi at Rome and from Heisenberg at Leipzig. He worked at institutions near Washington, D. C. during the war, and joined the staff of the National Bureau of Standards in 1946. He became a professor of physics at The University of Chicago in 1966. His contributions to radiation physics, atomic and molecular physics, and statistical physics are extensive and outstanding. Recognition includes many honors such as the Fermi Award by the DOE, and terms such as the Beutler-Fano profile of certain spectral lines, the Fano factor characterizing the fluctuations of the radiation-induced ionization, the Fano-Lichten mechanism for inelastic atomic collisions, and the Fano effect leading to spin-polarized photoelectrons. His work follows a style inherited from Fermi and is characterized by incisive insight into the physics behind experimental data, penetrating mathematical analysis, and close communications with many colleagues. Because he took a leading role in developing new areas of research and in nurturing young scientists, his influence now permeates many topics of physics. They include far uv and soft x-ray spectroscopy with synchrotron radiation and fundamental radiological physics, both stemming from his time at NBS, as well as multi-channel quantum-defect theory and hyperspherical-coordinate approach, both pioneered at Chicago. Fuller accounts of his life and science are seen in Inokuti [1], in Rau [2], and in a forthcoming special issue of Physics Essays in his honor. The present work is supported by U. S. DOE, Office of Science, Nuclear Physics Division, under Contract No. W-31-109-Eng-38. References 1. M. Inokuti, in Fundamental Processes of Atomic Dynamics, J. S. Briggs et al. (eds.), (Plenum, New York, 1988), p. 1. 2. A. R. P. Rau, Comments At. Mol. Phys. 33, 181 (1997).

Semantic modeling of the structural and process entities during plastic deformation of crystals and rocks

NASA Astrophysics Data System (ADS)

Babaie, Hassan; Davarpanah, Armita

2016-04-01

We are semantically modeling the structural and dynamic process components of the plastic deformation of minerals and rocks in the Plastic Deformation Ontology (PDO). Applying the Ontology of Physics in Biology, the PDO classifies the spatial entities that participate in the diverse processes of plastic deformation into the Physical_Plastic_Deformation_Entity and Nonphysical_Plastic_Deformation_Entity classes. The Material_Physical_Plastic_Deformation_Entity class includes things such as microstructures, lattice defects, atoms, liquid, and grain boundaries, and the Immaterial_Physical_Plastic_Deformation_Entity class includes vacancies in crystals and voids along mineral grain boundaries. The objects under the many subclasses of these classes (e.g., crystal, lattice defect, layering) have spatial parts that are related to each other through taxonomic (e.g., Line_Defect isA Lattice_Defect), structural (mereological, e.g., Twin_Plane partOf Twin), spatial-topological (e.g., Vacancy adjacentTo Atom, Fluid locatedAlong Grain_Boundary), and domain specific (e.g., displaces, Fluid crystallizes Dissolved_Ion, Void existsAlong Grain_Boundary) relationships. The dynamic aspect of the plastic deformation is modeled under the dynamical Process_Entity class that subsumes classes such as Recrystallization and Pressure_Solution that define the flow of energy amongst the physical entities. The values of the dynamical state properties of the physical entities (e.g., Chemical_Potential, Temperature, Particle_Velocity) change while they take part in the deformational processes such as Diffusion and Dislocation_Glide. The process entities have temporal parts (phases) that are related to each other through temporal relations such as precedes, isSubprocessOf, and overlaps. The properties of the physical entities, defined under the Physical_Property class, change as they participate in the plastic deformational processes. The properties are categorized into dynamical, constitutive, spatial, temporal, statistical, and thermodynamical. The dynamical properties, categorized under the Dynamical_Rate_Property and Dynamical_State_Property classes, subsume different classes of properties (e.g., Fluid_Flow_Rate, Temperature, Chemical_Potential, Displacement, Electrical_Charge) based on the physical domain (e.g., fluid, heat, chemical, solid, electrical). The properties are related to the objects under the Physical_Entity class through diverse object type (e.g., physicalPropertyOf) and data type (e.g., Fluid_Pressure unit 'MPa') properties. The changes of the dynamical properties of the physical entities, described by the empirical laws (equations) modeled by experimental structural geologists, are modeled through the Physical_Property_Dependency class that subsumes the more specialized constitutive, kinetic, and thermodynamic expressions of the relationships among the dynamic properties. Annotation based on the PDO will make it possible to integrate and reuse experimental plastic deformation data, knowledge, and simulation models, and conduct semantic-based search of the source data originating from different rock testing laboratories.

Continuous measurement of an atomic current

NASA Astrophysics Data System (ADS)

Laflamme, C.; Yang, D.; Zoller, P.

2017-04-01

We are interested in dynamics of quantum many-body systems under continuous observation, and its physical realizations involving cold atoms in lattices. In the present work we focus on continuous measurement of atomic currents in lattice models, including the Hubbard model. We describe a Cavity QED setup, where measurement of a homodyne current provides a faithful representation of the atomic current as a function of time. We employ the quantum optical description in terms of a diffusive stochastic Schrödinger equation to follow the time evolution of the atomic system conditional to observing a given homodyne current trajectory, thus accounting for the competition between the Hamiltonian evolution and measurement back action. As an illustration, we discuss minimal models of atomic dynamics and continuous current measurement on rings with synthetic gauge fields, involving both real space and synthetic dimension lattices (represented by internal atomic states). Finally, by "not reading" the current measurements the time evolution of the atomic system is governed by a master equation, where—depending on the microscopic details of our CQED setups—we effectively engineer a current coupling of our system to a quantum reservoir. This provides interesting scenarios of dissipative dynamics generating "dark" pure quantum many-body states.

10 CFR Appendix C to Part 73 - Nuclear Power Plant Safeguards Contingency Plans

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Nuclear Power Plant Safeguards Contingency Plans C Appendix C to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND... sabotage relating to special nuclear material or nuclear facilities licensed under the Atomic Energy Act of...

10 CFR Appendix C to Part 73 - Nuclear Power Plant Safeguards Contingency Plans

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Nuclear Power Plant Safeguards Contingency Plans C Appendix C to Part 73 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) PHYSICAL PROTECTION OF PLANTS AND... sabotage relating to special nuclear material or nuclear facilities licensed under the Atomic Energy Act of...

Ab initio simulations of subatomic resolution images in noncontact atomic force microscopy

NASA Astrophysics Data System (ADS)

Kim, Minjung; Chelikowsky, James R.

2015-03-01

Direct imaging of polycyclic aromatic molecules with a subatomic resolution has recently been achieved with noncontact atomic force microscopy (nc-AFM). Specifically, nc-AFM employing a CO functionalized tip has provided details of the chemical bond in aromatic molecules, including the discrimination of bond order. However, the underlying physics of such high resolution imaging remains problematic. By employing new, efficient algorithms based on real space pseudopotentials, we calculate the forces between the nc-AFM tip and specimen. We simulate images of planar organic molecules with two different approaches: 1) with a chemically inert tip and 2) with a CO functionalized tip. We find dramatic differences in the resulting images, which are consistent with recent experimental work. Our work is supported by the DOE under DOE/DE-FG02-06ER46286 and by the Welch Foundation under Grant F-1837. Computational resources were provided by NERSC and XSEDE.

Plasma physics goes beyond fusion

NASA Astrophysics Data System (ADS)

Franklin, Raoul

2008-11-01

I was interested to read the fusion supplement published with the October issue of Physics World. However, in asserting that fusion created the need to recognize plasma physics as a separate branch of the subject, Stephen Cowley, the new director of the United Kingdom Atomic Energy Authority, was not quite correct. In fact, the word "plasma" was appropriated from the Greek by the chemical physicist (and later Nobel laureate) Irving Langmuir in 1928. It was used to describe the positive column of a gas discharge, which was then the subject of research into better lighting sources and advertising displays, as well as the underlying science.

The Strength of Chaos: Accurate Simulation of Resonant Electron Scattering by Many-Electron Ions and Atoms in the Presence of Quantum Chaos

DTIC Science & Technology

2017-01-20

September 2016 PI and Co-PI information: Igor Bray; I.Bray@curtin.edu.au; Curtin University; Department of Physics , Astronomy and Medical Radiation... astrophysics , fusion energy through to cancer imaging and therapy. During the last two decades there has been immense progress in the field of...Theoretical Physics Division, at the Los Alamos National Laboratory. Theory: The underlying theoretical approach to collisions that we use is known as the

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.

Learning molecular energies using localized graph kernels

DOE PAGES

Ferré, Grégoire; Haut, Terry Scot; Barros, Kipton Marcos

2017-03-21

We report that recent machine learning methods make it possible to model potential energy of atomic configurations with chemical-level accuracy (as calculated from ab initio calculations) and at speeds suitable for molecular dynamics simulation. Best performance is achieved when the known physical constraints are encoded in the machine learning models. For example, the atomic energy is invariant under global translations and rotations; it is also invariant to permutations of same-species atoms. Although simple to state, these symmetries are complicated to encode into machine learning algorithms. In this paper, we present a machine learning approach based on graph theory that naturallymore » incorporates translation, rotation, and permutation symmetries. Specifically, we use a random walk graph kernel to measure the similarity of two adjacency matrices, each of which represents a local atomic environment. This Graph Approximated Energy (GRAPE) approach is flexible and admits many possible extensions. Finally, we benchmark a simple version of GRAPE by predicting atomization energies on a standard dataset of organic molecules.« less

Learning molecular energies using localized graph kernels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferré, Grégoire; Haut, Terry Scot; Barros, Kipton Marcos

We report that recent machine learning methods make it possible to model potential energy of atomic configurations with chemical-level accuracy (as calculated from ab initio calculations) and at speeds suitable for molecular dynamics simulation. Best performance is achieved when the known physical constraints are encoded in the machine learning models. For example, the atomic energy is invariant under global translations and rotations; it is also invariant to permutations of same-species atoms. Although simple to state, these symmetries are complicated to encode into machine learning algorithms. In this paper, we present a machine learning approach based on graph theory that naturallymore » incorporates translation, rotation, and permutation symmetries. Specifically, we use a random walk graph kernel to measure the similarity of two adjacency matrices, each of which represents a local atomic environment. This Graph Approximated Energy (GRAPE) approach is flexible and admits many possible extensions. Finally, we benchmark a simple version of GRAPE by predicting atomization energies on a standard dataset of organic molecules.« less

Molecular dynamics simulation investigations of atomic-scale wear

NASA Astrophysics Data System (ADS)

Shao, Yuchong; Falk, Michael

2013-03-01

Frictional running-in and material transfer in wear take place at the micro- and nano-scale but the fundamental physics remain poorly understood. Here we intend to investigate wear and running-in phenomena in silicon based materials, which are widely utilized in micro/nano electromechanical systems(MEMS/NEMS). We use an atomic force microscopy (AFM) model composed of a crystalline silicon tip and substrate coated with native oxide layers. Molecular dynamics simulation has been performed over a range of temperatures, external loads and slip rates. Results show that adhesive wear takes place across the interface in an atom-by-atom fashion which remodels the tip leading to a final steady state. We quantify the rate of material transfer as a function of the coverage of non-bridging oxygen (NBO) atoms, which has a pronounced change of the system's tribological and wear behaviors. A constitutive rate and state model is proposed to predict the evolution of frictional strength and wear. This work is supported by the National Science Foundation under Award No. 0926111.

Laser photochemical lead isotopes separation for harmless nuclear power engineering

NASA Astrophysics Data System (ADS)

Bokhan, P. A.; Fateev, N. V.; Kim, V. A.; Zakrevsky, D. E.

2016-09-01

The collisional quenching of the metastable 3 P 1,2 and 1 D 2 lead atoms is studied experimentally in the gas flow of the lead atoms, reagent-molecules and a carrier gas Ar. The experimental parameters were similar to the conditions that are required in the operation of the experimental setup for photochemical isotope separation. Excited atoms are generated under electron impact conditions created by a gas glow discharge through the mixture of gases and monitored photoelectrically by attenuation of atomic resonance radiation from hollow cathode 208Pb lamp. The decay of the excited atoms has been studied in the presence various molecules and total cross section data are reported. The flow tube measurements has allowed to separate the physical and chemical quenching channels and measure the rates of the chemical reaction excited lead with N2O, CH2Cl2, SF6 and CuBr molecules. These results are discussed in the prospects of the obtaining isotopically modified lead as a promising coolant in the reactors on the fast-neutron.

Lasers, Cold Atoms and Atomic Clocks: Realizing the Second Today

NASA Astrophysics Data System (ADS)

Calonico, Davide

2013-09-01

The time is the physical quantity that mankind could measure with the best accuracy, thanks to the properties of the atomic physics, as the present definition of time is based on atomic energy transitions. This short review gives some basic information on the heart of the measurement of time in the contemporary world, i.e. the atomic clocks, and some trends related.

Roadmap of ultrafast x-ray atomic and molecular physics

NASA Astrophysics Data System (ADS)

Young, Linda; Ueda, Kiyoshi; Gühr, Markus; Bucksbaum, Philip H.; Simon, Marc; Mukamel, Shaul; Rohringer, Nina; Prince, Kevin C.; Masciovecchio, Claudio; Meyer, Michael; Rudenko, Artem; Rolles, Daniel; Bostedt, Christoph; Fuchs, Matthias; Reis, David A.; Santra, Robin; Kapteyn, Henry; Murnane, Margaret; Ibrahim, Heide; Légaré, François; Vrakking, Marc; Isinger, Marcus; Kroon, David; Gisselbrecht, Mathieu; L'Huillier, Anne; Wörner, Hans Jakob; Leone, Stephen R.

2018-02-01

X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (1020 W cm-2) of x-rays at wavelengths down to ˜1 Ångstrom, and HHG provides unprecedented time resolution (˜50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scales can be referenced to the chemically significant carbon K-edge at a photon energy of ˜280 eV (44 Ångstroms) and the bond length in methane of ˜1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.

Roadmap of ultrafast x-ray atomic and molecular physics

DOE PAGES

Young, Linda; Ueda, Kiyoshi; Gühr, Markus; ...

2018-01-09

X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (10 20 W cm -2) of x-rays at wavelengths down to ~1 Ångstrom, and HHG provides unprecedented time resolution (~50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scalesmore » can be referenced to the chemically significant carbon K-edge at a photon energy of ~280 eV (44 Ångstroms) and the bond length in methane of ~1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here in this paper, we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.« less

Roadmap of ultrafast x-ray atomic and molecular physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Linda; Ueda, Kiyoshi; Gühr, Markus

X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (10 20 W cm -2) of x-rays at wavelengths down to ~1 Ångstrom, and HHG provides unprecedented time resolution (~50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scalesmore » can be referenced to the chemically significant carbon K-edge at a photon energy of ~280 eV (44 Ångstroms) and the bond length in methane of ~1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here in this paper, we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science.« less

Spontaneous spherical symmetry breaking in atomic confinement

NASA Astrophysics Data System (ADS)

Sveshnikov, Konstantin; Tolokonnikov, Andrey

2017-07-01

The effect of spontaneous breaking of initial SO(3) symmetry is shown to be possible for an H-like atom in the ground state, when it is confined in a spherical box under general boundary conditions of "not going out" through the box surface (i.e. third kind or Robin's ones), for a wide range of physically reasonable values of system parameters. The most novel and nontrivial result, which has not been reported previously, is that such an effect takes place not only for attractive, but also for repulsive interactions of atomic electrons with the cavity environment. Moreover, in the limit of a large box size R ≫ aB the regime of an atom, soaring over a plane with boundary condition of "not going out", is reproduced, rather than a spherically symmetric configuration, which would be expected on the basis of the initial SO(3) symmetry of the problem.

Neutral atoms facility for space sensors characterization and BepiColombo/ELENA development instrument's progresses.

NASA Astrophysics Data System (ADS)

de Angelis, E.; di Lellis, A. M.; Orsini, S.; Zanza, V.; Maggi, M.; Vertolli, N.; D'Amicis, R.; Tilia, B.; Sibio, A.

2003-04-01

An Energetic Neutral Atoms facility to test and calibrate Neutral Atoms Analyzers has been developed in the Scientific Technical Unit of Fusion at the ENEA Research Center in Frascati (Rome-Italy). In the last years a collaboration with IFSI (Interplanetary Space and Physics Institute, CNR-Rome-Italy) has allowed to use this facility for space sensors and for characterization of crucial instruments elements. The ENA beam is realized with an ion source and a neutralization cell, and allows to test any instrument in the energy range 300eV-110keV with the available masses of Hydrogen, Deuterium or Helium. At the moment, the critical elements of ELENA (Emitted Low Energy Neutral Atoms) instrument proposed for BepiColombo ESA cornerstone mission to Mercury is under development testing. The facility, its potentiality and the instrument characterization progresses are presented.

Llewellyn Hilleth Thomas: An appraisal of an under-appreciated polymath

NASA Astrophysics Data System (ADS)

Jackson, John David

2010-02-01

Llewellyn Hilleth Thomas was born in 1903 and died in 1992 at the age of 88. His name is known by most for only two things, Thomas precession and the Thomas-Fermi atom. The many other facets of his career - astrophysics, atomic and molecular physics, nonlinear problems, accelerator physics, magnetohydrodynamics, computer design principles and software and hardware - are largely unknown or forgotten. I review his whole career - his early schooling, his time at Cambridge, then Copenhagen in 1925-26, and back to Cambridge, his move to the US as an assistant professor at Ohio State University in 1929, his wartime years at the Ballistic Research Laboratory, Aberdeen Proving Grounds, then in 1946 his new career as a unique resource at IBM's Watson Scientific Computing Laboratory and Columbia University until his first retirement in 1968, and his twilight years at North Carolina State University. Although the Thomas precession and the Thomas-Fermi atom may be the jewels in his crown, his many other accomplishments add to our appreciation of this consummate applied mathematician and physicist. )

Topology, localization, and quantum information in atomic, molecular and optical systems

NASA Astrophysics Data System (ADS)

Yao, Norman Ying

The scientific interface between atomic, molecular and optical (AMO) physics, condensed matter, and quantum information science has recently led to the development of new insights and tools that bridge the gap between macroscopic quantum behavior and detailed microscopic intuition. While the dialogue between these fields has sharpened our understanding of quantum theory, it has also raised a bevy of new questions regarding the out-of-equilibrium dynamics and control of many-body systems. This thesis is motivated by experimental advances that make it possible to produce and probe isolated, strongly interacting ensembles of disordered particles, as found in systems ranging from trapped ions and Rydberg atoms to ultracold polar molecules and spin defects in the solid state. The presence of strong interactions in these systems underlies their potential for exploring correlated many-body physics and this thesis presents recent results on realizing fractionalization and localization. From a complementary perspective, the controlled manipulation of individual quanta can also enable the bottom-up construction of quantum devices. To this end, this thesis also describes blueprints for a room-temperature quantum computer, quantum credit cards and nanoscale quantum thermometry.

An Overview of the State of the Art in Atomistic and Multiscale Simulation of Fracture

NASA Technical Reports Server (NTRS)

Saether, Erik; Yamakov, Vesselin; Phillips, Dawn R.; Glaessgen, Edward H.

2009-01-01

The emerging field of nanomechanics is providing a new focus in the study of the mechanics of materials, particularly in simulating fundamental atomic mechanisms involved in the initiation and evolution of damage. Simulating fundamental material processes using first principles in physics strongly motivates the formulation of computational multiscale methods to link macroscopic failure to the underlying atomic processes from which all material behavior originates. This report gives an overview of the state of the art in applying concurrent and sequential multiscale methods to analyze damage and failure mechanisms across length scales.

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

PubMed

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

2017-04-21

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

Dynamics of entropy and nonclassical properties of the state of a Λ-type three-level atom interacting with a single-mode cavity field with intensity-dependent coupling in a Kerr medium

NASA Astrophysics Data System (ADS)

Faghihi, M. J.; Tavassoly, M. K.

2012-02-01

In this paper, we study the interaction between a three-level atom and a quantized single-mode field with ‘intensity-dependent coupling’ in a ‘Kerr medium’. The three-level atom is considered to be in a Λ-type configuration. Under particular initial conditions, which may be prepared for the atom and the field, the dynamical state vector of the entire system will be explicitly obtained, for the arbitrary nonlinearity function f(n) associated with any physical system. Then, after evaluating the variation of the field entropy against time, we will investigate the quantum statistics as well as some of the nonclassical properties of the introduced state. During our calculations we investigate the effects of intensity-dependent coupling, Kerr medium and detuning parameters on the depth and domain of the nonclassicality features of the atom-field state vector. Finally, we compare our obtained results with those of V-type three-level atoms.

Fisher information due to a phase noisy laser under non-Markovian environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel-Khalek, S., E-mail: sayedquantum@yahoo.co.uk

2014-12-15

More recently, K. Berrada [Annals of Physics 340 (2014) 60-69] [1] studied the geometric phase of a two-level atom system driven by a phase noise laser under non-Markovian dynamics in terms of different parameters involved in the whole system, and collapse and revival phenomena were found for large class of states. In this paper, using this noise effect, we study the quantum fisher information (QFI) for a two-level atom system driven by a phase noise laser under non-Markovian dynamics. A new quantity, called QFI flow is used to characterize the damping effect and unveil a fundamental connection between non-Markovian behaviormore » and dynamics of system–environment correlations under phase noise laser. It is shown that QFI flow has disappeared suddenly followed by a sudden birth depending on the kind of the environment damping. QFI flow provides an indicator to characterize the dissipative quantum system’s decoherence by analyzing the behavior of the dynamical non-Markovian coefficients.« less

Underground atom gradiometer array for mass distribution monitoring and advanced geodesy

NASA Astrophysics Data System (ADS)

Canuel, B.

2015-12-01

After more than 20 years of fundamental research, atom interferometers have reached sensitivity and accuracy levels competing with or beating inertial sensors based on different technologies. Atom interferometers offer interesting applications in geophysics (gravimetry, gradiometry, Earth rotation rate measurements), inertial sensing (submarine or aircraft autonomous positioning), metrology (new definition of the kilogram) and fundamental physics (tests of the standard model, tests of general relativity). Atom interferometers already contributed significantly to fundamental physics by, for example, providing stringent constraints on quantum-electrodynamics through measurements of the hyperfine structure constant, testing the Equivalence Principle with cold atoms, or providing new measurements for the Newtonian gravitational constant. Cold atom sensors have moreover been established as key instruments in metrology for the new definition of the kilogram or through international comparisons of gravimeters. The field of atom interferometry (AI) is now entering a new phase where very high sensitivity levels must be demonstrated, in order to enlarge the potential applications outside atomic physics laboratories. These applications range from gravitational wave (GW) detection in the [0.1-10 Hz] frequency band to next generation ground and space-based Earth gravity field studies to precision gyroscopes and accelerometers. The Matter-wave laser Interferometric Gravitation Antenna (MIGA) presented here is a large-scale matter-wave sensor which will open new applications in geoscience and fundamental physics. The MIGA consortium gathers 18 expert French laboratories and companies in atomic physics, metrology, optics, geosciences and gravitational physics, with the aim to build a large-scale underground atom-interferometer instrument by 2018 and operate it till at least 2023. In this paper, we present the main objectives of the project, the status of the construction of the instrument and the motivation for the applications of MIGA in geosciences

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

PubMed

Pederson, Thoru; Marko, John F

2014-11-05

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

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…

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

NASA Astrophysics Data System (ADS)

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

2008-11-01

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

Light scattering from an atomic gas under conditions of quantum degeneracy

NASA Astrophysics Data System (ADS)

Porozova, V. M.; Gerasimov, L. V.; Havey, M. D.; Kupriyanov, D. V.

2018-05-01

Elastic light scattering from a macroscopic atomic sample existing in the Bose-Einstein condensate phase reveals a unique physical configuration of interacting light and matter waves. However, the joint coherent dynamics of the optical excitation induced by an incident photon is influenced by the presence of incoherent scattering channels. For a sample of sufficient length the excitation transports as a polariton wave and the propagation Green's function obeys the scattering equation which we derive. The polariton dynamics could be tracked in the outgoing channel of the scattered photon as we show via numerical solution of the scattering equation for one-dimensional geometry. The results are analyzed and compared with predictions of the conventional macroscopic Maxwell theory for light scattering from a nondegenerate atomic sample of the same density and size.

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)

Implementation of atomic layer deposition-based AlON gate dielectrics in AlGaN/GaN MOS structure and its physical and electrical properties

NASA Astrophysics Data System (ADS)

Nozaki, Mikito; Watanabe, Kenta; Yamada, Takahiro; Shih, Hong-An; Nakazawa, Satoshi; Anda, Yoshiharu; Ueda, Tetsuzo; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2018-06-01

Alumina incorporating nitrogen (aluminum oxynitride; AlON) for immunity against charge injection was grown on a AlGaN/GaN substrate through the repeated atomic layer deposition (ALD) of AlN layers and in situ oxidation in ozone (O3) ambient under optimized conditions. The nitrogen distribution was uniform in the depth direction, the composition was controllable over a wide range (0.5–32%), and the thickness could be precisely controlled. Physical analysis based on synchrotron radiation X-ray photoelectron spectroscopy (SR-XPS) revealed that harmful intermixing at the insulator/AlGaN interface causing Ga out-diffusion in the gate stack was effectively suppressed by this method. AlON/AlGaN/GaN MOS capacitors were fabricated, and they had excellent electrical properties and immunity against electrical stressing as a result of the improved interface stability.

Optical Atomic Clock for Fundamental Physics and Precision Metrology in Space

NASA Astrophysics Data System (ADS)

Williams, Jason; Le, Thanh; Kulas, Sascha; Yu, Nan

2017-04-01

The maturity of optical atomic clocks (OC), which operate at optical frequencies for higher quality-factor as compared to their microwave counterparts, has rapidly progressed to the point where lab-based systems now outperform the record cesium clocks by orders of magnitude in both accuracy and stability. We will present our efforts to develop a strontium optical clock testbed at JPL, aimed towards extending the exceptional performance demonstrated by OCs from state-of-the-art laboratory designs to a transportable instrument that can fit within the space and power constraints of e.g. a single express rack onboard the International Space Station. The overall technology will find applications for future fundamental physics research, both on ground and in space, precision time keeping, and NASA/JPL time and frequency test capabilities. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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

PubMed Central

2014-01-01

Summary This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip–sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip–sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip–sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided. PMID:25383277

Physics Division progress report for period ending September 30, 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

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)

Atomic-scale imaging of DNA using scanning tunnelling microscopy.

PubMed

Driscoll, R J; Youngquist, M G; Baldeschwieler, J D

1990-07-19

The scanning tunnelling microscope (STM) has been used to visualize DNA under water, under oil and in air. Images of single-stranded DNA have shown that submolecular resolution is possible. Here we describe atomic-resolution imaging of duplex DNA. Topographic STM images of uncoated duplex DNA on a graphite substrate obtained in ultra-high vacuum are presented that show double-helical structure, base pairs, and atomic-scale substructure. Experimental STM profiles show excellent correlation with atomic contours of the van der Waals surface of A-form DNA derived from X-ray crystallography. A comparison of variations in the barrier to quantum mechanical tunnelling (barrier-height) with atomic-scale topography shows correlation over the phosphate-sugar backbone but anticorrelation over the base pairs. This relationship may be due to the different chemical characteristics of parts of the molecule. Further investigation of this phenomenon should lead to a better understanding of the physics of imaging adsorbates with the STM and may prove useful in sequencing DNA. The improved resolution compared with previously published STM images of DNA may be attributable to ultra-high vacuum, high data-pixel density, slow scan rate, a fortuitously clean and sharp tip and/or a relatively dilute and extremely clean sample solution. This work demonstrates the potential of the STM for characterization of large biomolecular structures, but additional development will be required to make such high resolution imaging of DNA and other large molecules routine.

Isotropic Inelastic Collisions in a Multiterm Atom with Hyperfine Structure

NASA Astrophysics Data System (ADS)

Belluzzi, Luca; Landi Degl'Innocenti, Egidio; Trujillo Bueno, Javier

2015-10-01

A correct modeling of the scattering polarization profiles observed in some spectral lines of diagnostic interest, the sodium doublet being one of the most important examples, requires taking hyperfine structure (HFS) and quantum interference between different J-levels into account. An atomic model suitable for taking these physical ingredients into account is the so-called multiterm atom with HFS. In this work, we introduce and study the transfer and relaxation rates due to isotropic inelastic collisions with electrons, which enter the statistical equilibrium equations (SEE) for the atomic density matrix of this atomic model. Under the hypothesis that the electron-atom interaction is described by a dipolar operator, we provide useful relations between the rates describing the transfer and relaxation of quantum interference between different levels (whose numerical values are in most cases unknown) and the usual rates for the atomic level populations, for which experimental data and/or approximate theoretical expressions are generally available. For the particular case of a two-term atom with HFS, we present an analytical solution of the SEE for the spherical statistical tensors of the upper term, including both radiative and collisional processes, and we derive the expression of the emission coefficient in the four Stokes parameters. Finally, an illustrative application to the Na i D1 and D2 lines is presented.

Relativistic quantum optics: The relativistic invariance of the light-matter interaction models

NASA Astrophysics Data System (ADS)

Martín-Martínez, Eduardo; Rodriguez-Lopez, Pablo

2018-05-01

In this article we discuss the invariance under general changes of reference frame of all the physical predictions of particle detector models in quantum field theory in general and, in particular, of those used in quantum optics to model atoms interacting with light. We find explicitly how the light-matter interaction Hamiltonians change under general coordinate transformations, and analyze the subtleties of the Hamiltonians commonly used to describe the light-matter interaction when relativistic motion is taken into account.

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.

The Deformations of Carbon Nanotubes under Cutting.

PubMed

Deng, Jue; Wang, Chao; Guan, Guozhen; Wu, Hao; Sun, Hong; Qiu, Longbin; Chen, Peining; Pan, Zhiyong; Sun, Hao; Zhang, Bo; Che, Renchao; Peng, Huisheng

2017-08-22

The determination of structural evolution at the atomic level is essential to understanding the intrinsic physics and chemistries of nanomaterials. Mechanochemistry represents a promising method to trace structural evolution, but conventional mechanical tension generates random breaking points, which makes it unavailable for effective analysis. It remains difficult to find an appropriate model to study shear deformations. Here, we synthesize high-modulus carbon nanotubes that can be cut precisely, and the structural evolution is efficiently investigated through a combination of geometry phase analysis and first-principles calculations. The lattice fluctuation depends on the anisotropy, chirality, curvature, and slicing rate. The strain distribution further reveals a plastic breaking mechanism for the conjugated carbon atoms under cutting. The resulting sliced carbon nanotubes with controllable sizes and open ends are promising for various applications, for example, as an anode material for lithium-ion batteries.

Improving atomic displacement and replacement calculations with physically realistic damage models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nordlund, Kai; Zinkle, Steven J.; Sand, Andrea E.

Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor ofmore » 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.« less

Improving atomic displacement and replacement calculations with physically realistic damage models

DOE PAGES

Nordlund, Kai; Zinkle, Steven J.; Sand, Andrea E.; ...

2018-03-14

Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor ofmore » 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.« less

Improving atomic displacement and replacement calculations with physically realistic damage models.

PubMed

Nordlund, Kai; Zinkle, Steven J; Sand, Andrea E; Granberg, Fredric; Averback, Robert S; Stoller, Roger; Suzudo, Tomoaki; Malerba, Lorenzo; Banhart, Florian; Weber, William J; Willaime, Francois; Dudarev, Sergei L; Simeone, David

2018-03-14

Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during primary displacement events. The current international standard for quantifying this energetic particle damage, the Norgett-Robinson-Torrens displacements per atom (NRT-dpa) model, has nowadays several well-known limitations. In particular, the number of radiation defects produced in energetic cascades in metals is only ~1/3 the NRT-dpa prediction, while the number of atoms involved in atomic mixing is about a factor of 30 larger than the dpa value. Here we propose two new complementary displacement production estimators (athermal recombination corrected dpa, arc-dpa) and atomic mixing (replacements per atom, rpa) functions that extend the NRT-dpa by providing more physically realistic descriptions of primary defect creation in materials and may become additional standard measures for radiation damage quantification.

The crystallography of correlated disorder.

PubMed

Keen, David A; Goodwin, Andrew L

2015-05-21

Classical crystallography can determine structures as complicated as multi-component ribosomal assemblies with atomic resolution, but is inadequate for disordered systems--even those as simple as water ice--that occupy the complex middle ground between liquid-like randomness and crystalline periodic order. Correlated disorder nevertheless has clear crystallographic signatures that map to the type of disorder, irrespective of the underlying physical or chemical interactions and material involved. This mapping hints at a common language for disordered states that will help us to understand, control and exploit the disorder responsible for many interesting physical properties.

Direct visualization and in-depth physical study of metal filament formation in percolated high-κ dielectrics

NASA Astrophysics Data System (ADS)

Li, X.; Pey, K. L.; Bosman, M.; Liu, W. H.; Kauerauf, T.

2010-01-01

The migration of Ta atoms from a transistor gate electrode into the percolated high-κ (HK) gate dielectrics is directly shown using transmission electron microscopy analysis. A nanoscale metal filament that formed under high current injection is identified to be the physical defect responsible for the ultrafast transient breakdown (BD) of the metal-gate/high-κ (MG/HK) gate stacks. This highly conductive metal filament poses reliability concerns for MG/HK gate stacks as it significantly reduces the post-BD reliability margin of a transistor.

Impact of Coulomb potential on peak structures arising in momentum and low-energy photoelectron spectra produced in strong-field ionization of laser-irradiated atoms

NASA Astrophysics Data System (ADS)

Pyak, P. E.; Usachenko, V. I.

2018-03-01

The phenomenon of pronounced peak structure(s) of longitudinal momentum distributions as well as a spike-like structure of low-energy spectra of photoelectrons emitted from laser-irradiated Ar and Ne atoms in a single ionization process is theoretically studied in the tunneling and multiphoton regimes of ionization. The problem is addressed assuming only the direct above-threshold ionization (ATI) as a physical mechanism underlying the phenomenon under consideration (viz. solely contributing to observed photoelectron momentum distributions (PMD)) and using the Coulomb-Volkov (CV) ansatz within the frame of conventional strong-field approximation (SFA) applied in the length-gauge formulation. The developed CV-SFA approach also incorporates the density functional theory essentially exploited for numerical composition of initial (laser-free) atomic state(s) constructed from atomic orbitals of Gaussian type. Our presented CV-SFA based (and laser focal-volume averaged) calculation results proved to be well reproducing both the pronounced double-peak and/or ATI-like multi-peak structure(s) experimentally observed in longitudinal PMD under conditions of tunneling and/or multiphoton regime, respectively. In addition, our CV-SFA results presented for tunneling regime also suggest and remarkably reproduce a pronounced structure observed in relevant experiments as a ‘spike-like’ enhanced maximum arising in low-energy region (around the value of about 1 eV) of photoelectron spectra. The latter consistency allows to identify and interpret these results as the so-called low-energy structure (LES) since the phenomenon proved to appear as the most prominent if the influence of Coulomb potential on photoelectron continuum states is maximally taken into account under calculations (viz. if the parameter Z in CV’s functions is put equal to 1). Moreover, the calculated LES proved to correspond (viz., established as closely related) to the mentioned double-peak structure arising in the low-momentum region ({p}| | ≤slant | 0.2| a.u.) of longitudinal PMDs calculated under condition of the tunneling regime. Thus, the phenomena under consideration can be well understood and adequately interpreted beyond the terms and/or concepts of various different alternative strong-field approaches and models (such as e.g., extensively invoked and exploited nowadays though, more sophisticated SFA-based ‘rescattering’ mechanism) compared to which, the currently applied CV-SFA model (through the same underlying physical mechanism of solely direct ATI suggested) is additionally able to provide and reveal an intimate and transparent interrelation between the phenomena of LES and double-peak structure arising in PMDs observed in the tunneling regime.

Charge Transfer Reactions

NASA Astrophysics Data System (ADS)

Dennerl, Konrad

2010-12-01

Charge transfer, or charge exchange, describes a process in which an ion takes one or more electrons from another atom. Investigations of this fundamental process have accompanied atomic physics from its very beginning, and have been extended to astrophysical scenarios already many decades ago. Yet one important aspect of this process, i.e. its high efficiency in generating X-rays, was only revealed in 1996, when comets were discovered as a new class of X-ray sources. This finding has opened up an entirely new field of X-ray studies, with great impact due to the richness of the underlying atomic physics, as the X-rays are not generated by hot electrons, but by ions picking up electrons from cold gas. While comets still represent the best astrophysical laboratory for investigating the physics of charge transfer, various studies have already spotted a variety of other astrophysical locations, within and beyond our solar system, where X-rays may be generated by this process. They range from planetary atmospheres, the heliosphere, the interstellar medium and stars to galaxies and clusters of galaxies, where charge transfer may even be observationally linked to dark matter. This review attempts to put the various aspects of the study of charge transfer reactions into a broader historical context, with special emphasis on X-ray astrophysics, where the discovery of cometary X-ray emission may have stimulated a novel look at our universe.

Multi-million atom electronic structure calculations for quantum dots

NASA Astrophysics Data System (ADS)

Usman, Muhammad

Quantum dots grown by self-assembly process are typically constructed by 50,000 to 5,000,000 structural atoms which confine a small, countable number of extra electrons or holes in a space that is comparable in size to the electron wavelength. Under such conditions quantum dots can be interpreted as artificial atoms with the potential to be custom tailored to new functionality. In the past decade or so, these nanostructures have attracted significant experimental and theoretical attention in the field of nanoscience. The new and tunable optical and electrical properties of these artificial atoms have been proposed in a variety of different fields, for example in communication and computing systems, medical and quantum computing applications. Predictive and quantitative modeling and simulation of these structures can help to narrow down the vast design space to a range that is experimentally affordable and move this part of nanoscience to nano-Technology. Modeling of such quantum dots pose a formidable challenge to theoretical physicists because: (1) Strain originating from the lattice mismatch of the materials penetrates deep inside the buffer surrounding the quantum dots and require large scale (multi-million atom) simulations to correctly capture its effect on the electronic structure, (2) The interface roughness, the alloy randomness, and the atomistic granularity require the calculation of electronic structure at the atomistic scale. Most of the current or past theoretical calculations are based on continuum approach such as effective mass approximation or k.p modeling capturing either no or one of the above mentioned effects, thus missing some of the essential physics. The Objectives of this thesis are: (1) to model and simulate the experimental quantum dot topologies at the atomistic scale; (2) to theoretically explore the essential physics i.e. long range strain, linear and quadratic piezoelectricity, interband optical transition strengths, quantum confined stark shift, coherent coupling of electronic states in a quantum dot molecule etc.; (3) to assess the potential use of the quantum dots in real device implementation and to provide physical insight to the experimentalists. Full three dimensional strain and electronic structure simulations of quantum dot structures containing multi-million atoms are done using NEMO 3-D. Both single and vertically stacked quantum dot structures are analyzed in detail. The results show that the strain and the piezoelectricity significantly impact the electronic structure of these devices. This work shows that the InAs quantum dots when placed in the InGaAs quantum well red shifts the emission wavelength. Such InAs/GaAs-based optical devices can be used for optical-fiber based communication systems at longer wavelengths (1.3um -- 1.5um). Our atomistic simulations of InAs/InGaAs/GaAs quantum dots quantitatively match with the experiment and give the critical insight of the physics involved in these structures. A single quantum dot molecule is studied for coherent quantum coupling of electronic states under the influence of static electric field applied in the growth direction. Such nanostructures can be used in the implementation of quantum information technologies. A close quantitative match with the experimental optical measurements allowed us to get a physical insight into the complex physics of quantum tunnel couplings of electronic states as the device operation switches between atomic and molecular regimes. Another important aspect is to design the quantum dots for a desired isotropic polarization of the optical emissions. Both single and coupled quantum dots are studied for TE/TM ratio engineering. The atomistic study provides a detailed physical analysis of these computationally expensive large nanostructures and serves as a guide for the experimentalists for the design of the polarization independent devices for the optical communication systems.

Cracks dynamics under tensional stress - a DEM approach

NASA Astrophysics Data System (ADS)

Debski, Wojciech; Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Szpindler, Maciej

2017-04-01

Breaking and fragmentation of solid materials is an extremely complex process involving scales ranging from an atomic scale (breaking inter-atomic bounds) up to thousands of kilometers in case of catastrophic earthquakes (in energy scale it ranges from single eV up to 1024 J). Such a large scale span of breaking processes opens lot of questions like, for example, scaling of breaking processes, existence of factors controlling final size of broken area, existence of precursors, dynamics of fragmentation, to name a few. The classical approach to study breaking process at seismological scales, i.e., physical processes in earthquake foci, is essentially based on two factors: seismic data (mostly) and the continuum mechanics (including the linear fracture mechanics). Such approach has been gratefully successful in developing kinematic (first) and dynamic (recently) models of seismic rupture and explaining many of earthquake features observed all around the globe. However, such approach will sooner or latter face a limitation due to a limited information content of seismic data and inherit limitations of the fracture mechanics principles. A way of avoiding this expected limitation is turning an attention towards a well established in physics method of computational simulations - a powerful branch of contemporary physics. In this presentation we discuss preliminary results of analysis of fracturing dynamics under external tensional forces using the Discrete Element Method approach. We demonstrate that even under a very simplified tensional conditions, the fragmentation dynamics is a very complex process, including multi-fracturing, spontaneous fracture generation and healing, etc. We also emphasis a role of material heterogeneity on the fragmentation process.

The Atomic Mass Evaluation (AME2012): Status and Perspectives

NASA Astrophysics Data System (ADS)

Kondev, F. G.; Audi, G.; Wang, M.; Xu, X.; Wapstra, A. H.; MacCormick, M.; Pfeiffer, B.

2013-10-01

The atomic mass is a fundamental property of the nucleus that has wide applications in natural sciences and technology. The new evaluated mass table, AME2012, has been recently published as a collaborative effort between scientists from China, Europe and USA, under the leadership of G. Audi. It represents a significant update of the previous AME2003 evaluation by considering a large number of precise experimental results obtained at existing Penning Trap and Storage Ring facilities, thus expending the region of experimentally known masses towards exotic neutron- and proton-rich nuclei. Since the presence of isomers plays an important role in determining the masses of many nuclei, a complementary database, NUBASE2012, that contains the isomer-level properties for all nuclei was also developed. This presentation will briefly review recent achievements of the collaboration, present on-going activities, and reflect on ideas for future developments and challenges in the field of evaluation of atomic masses. The work at ANL was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.

Logical synchronization: how evidence and hypotheses steer atomic clocks

NASA Astrophysics Data System (ADS)

Myers, John M.; Madjid, F. Hadi

2014-05-01

A clock steps a computer through a cycle of phases. For the propagation of logical symbols from one computer to another, each computer must mesh its phases with arrivals of symbols from other computers. Even the best atomic clocks drift unforeseeably in frequency and phase; feedback steers them toward aiming points that depend on a chosen wave function and on hypotheses about signal propagation. A wave function, always under-determined by evidence, requires a guess. Guessed wave functions are coded into computers that steer atomic clocks in frequency and position—clocks that step computers through their phases of computations, as well as clocks, some on space vehicles, that supply evidence of the propagation of signals. Recognizing the dependence of the phasing of symbol arrivals on guesses about signal propagation elevates `logical synchronization.' from its practice in computer engineering to a dicipline essential to physics. Within this discipline we begin to explore questions invisible under any concept of time that fails to acknowledge the unforeseeable. In particular, variation of spacetime curvature is shown to limit the bit rate of logical communication.

What is life? Bio-physical perspectives.

PubMed

Gladyshev, G P

2009-01-01

Life arises and develops in gravitationally bound atomic systems, under certain conditions, in the presence of the inflow of energy. A condition of structural dynamic reactivity to the energy inflow qualifies what are anthropomorphically considered as "alive objects". Alive objects, in this perspective, include such rudimentary animate atomic structures as the retinal molecule C20H28o to the herpes simplex virus C102H152N26o29 to the human being, a twenty-six element atomic structure, which can be quantified further as thermodynamic quasi-closed supramolecular systems, which are part of natural open systems. These systems appear and evolve in periodic conditions near to internal equilibrium. This systems attribute of dynamic life can be understood further by the determination and use of mathematical "state functions", which are functions that quantify the state of a system defined by the ensemble of physical quantities: temperature, pressure, composition, etc., which characterize the system, but neither by its surroundings nor by its history. In this view, the phenomenon of a life is easily understood as a general consequence of the laws of the universe, in particular, the laws of thermodynamics, which in the geocentric perspective translate to a formulation of "hierarchical thermodynamics" and a "principle of substance stability". The formation of living thermodynamic structures, in short, arises on the nanolevel by a constantly varying environment that causes variety of living forms. The definition of a life as the bio-chemical-physical phenomenon can thus be given on the basis of the exact sciences, i. e. chemistry, physics, and thermodynamics, without mention of numerous private attributes of a living substance and without physically baseless models of mathematical modeling, such as Prigoginean thermodynamics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thayer, K.J.

The past year has seen several of the Physics Division`s new research projects reach major milestones with first successful experiments and results: the atomic physics station in the Basic Energy Sciences Research Center at the Argonne Advanced Photon Source was used in first high-energy, high-brilliance x-ray studies in atomic and molecular physics; the Short Orbit Spectrometer in Hall C at the Thomas Jefferson National Accelerator (TJNAF) Facility that the Argonne medium energy nuclear physics group was responsible for, was used extensively in the first round of experiments at TJNAF; at ATLAS, several new beams of radioactive isotopes were developed andmore » used in studies of nuclear physics and nuclear astrophysics; the new ECR ion source at ATLAS was completed and first commissioning tests indicate excellent performance characteristics; Quantum Monte Carlo calculations of mass-8 nuclei were performed for the first time with realistic nucleon-nucleon interactions using state-of-the-art computers, including Argonne`s massively parallel IBM SP. At the same time other future projects are well under way: preparations for the move of Gammasphere to ATLAS in September 1997 have progressed as planned. These new efforts are imbedded in, or flowing from, the vibrant ongoing research program described in some detail in this report: nuclear structure and reactions with heavy ions; measurements of reactions of astrophysical interest; studies of nucleon and sub-nucleon structures using leptonic probes at intermediate and high energies; atomic and molecular structure with high-energy x-rays. The experimental efforts are being complemented with efforts in theory, from QCD to nucleon-meson systems to structure and reactions of nuclei. Finally, the operation of ATLAS as a national users facility has achieved a new milestone, with 5,800 hours beam on target for experiments during the past fiscal year.« less

The Separate and Collective Effects of Personalization, Personification, and Gender on Learning with Multimedia Chemistry Instructional Materials

ERIC Educational Resources Information Center

Halkyard, Shannon

2012-01-01

Chemistry is a difficult subject to learn and teach for students in general. Additionally, female students are under-represented in chemistry and the physical sciences. Within chemistry, atomic and electronic structure is a key concept and several recommendations in the literature describe how this topic can be taught better. These recommendations…

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,…

ALICE: A non-LTE plasma atomic physics, kinetics and lineshape package

NASA Astrophysics Data System (ADS)

Hill, E. G.; Pérez-Callejo, G.; Rose, S. J.

2018-03-01

All three parts of an atomic physics, atomic kinetics and lineshape code, ALICE, are described. Examples of the code being used to model the emissivity and opacity of plasmas are discussed and interesting features of the code which build on the existing corpus of models are shown throughout.

Spray formation processes of impinging jet injectors

NASA Technical Reports Server (NTRS)

Anderson, W. E.; Ryan, H. M.; Pal, S.; Santoro, R. J.

1993-01-01

A study examining impinging liquid jets has been underway to determine physical mechanisms responsible for combustion instabilities in liquid bi-propellant rocket engines. Primary atomization has been identified as an important process. Measurements of atomization length, wave structure, and drop size and velocity distribution were made under various ambient conditions. Test parameters included geometric effects and flow effects. It was observed that pre-impingement jet conditions, specifically whether they were laminar or turbulent, had the major effect on primary atomization. Comparison of the measurements with results from a two dimensional linear aerodynamic stability model of a thinning, viscous sheet were made. Measured turbulent impinging jet characteristics were contrary to model predictions; the structure of waves generated near the point of jet impingement were dependent primarily on jet diameter and independent of jet velocity. It has been postulated that these impact waves are related to pressure and momentum fluctuations near the impingement region and control the eventual disintegration of the liquid sheet into ligaments. Examination of the temporal characteristics of primary atomization (ligament shedding frequency) strongly suggests that the periodic nature of primary atomization is a key process in combustion instability.

Comment on "Theoretical study of the dynamics of atomic hydrogen adsorbed on graphene multilayers"

NASA Astrophysics Data System (ADS)

Bonfanti, Matteo; Martinazzo, Rocco

2018-03-01

It is shown that the theoretical prediction of a transient magnetization in bilayer and multilayer graphene (M. Moaied et al., Phys. Rev. B 91, 155419 (2015), 10.1103/PhysRevB.91.155419) relies on an incorrect physical scenario for adsorption, namely, one in which H atoms adsorb barrierless on graphitic substrates and form a random adsorption pattern of monomers. Rather, according to experimental evidence, H atom sticking is an activated process, and adsorption is under kinetic control, largely ruled by a preferential sticking mechanism that leads to stable, nonmagnetic dimers at all but the smallest coverages (<0.004 ). Theory and experiments are reconciled by reconsidering the hydrogen atom adsorption energetics with the help of van der Waals-inclusive density functional calculations that properly account for the basis set superposition error. It is shown that today van der Waals-density functional theory predicts a shallow physisorption well that nicely agrees with available experimental data and suggests that the hydrogen atom adsorption barrier in graphene is 180 meV high, within ˜5 meV accuracy.

Mesoscopic coherence in light scattering from cold, optically dense and disordered atomic systems

NASA Astrophysics Data System (ADS)

Kupriyanov, D. V.; Sokolov, I. M.; Havey, M. D.

2017-02-01

Coherent effects manifested in light scattering from cold, optically dense and disordered atomic systems are reviewed from a primarily theoretical point of view. Development of the basic theoretical tools is then elaborated through several physical atomic physics based processes which have been at least partly explored experimentally. These include illustrations drawn from the coherent backscattering effect, random lasing in atomic gases, quantum memories and light-atoms interface assisted by the light trapping mechanism. Current understanding and challenges associated with the transition to high atomic densities and cooperativity in the scattering process are also discussed in some detail.

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

NASA Astrophysics Data System (ADS)

Mewe, R.

1999-07-01

This book contains a comprehensive description of the basic principles of the theoretical spectroscopy and experimental spectroscopic diagnostics of Rydberg atoms and ions, i.e., atoms in highly excited states with a very large principal quantum number (n≫1). Rydberg atoms are characterized by a number of peculiar physical properties as compared to atoms in the ground or a low excited state. They have a very small ionization potential (∝1/n2), the highly excited electron has a small orbital velocity (∝1/n), the radius (∝n2) is very large, the excited electron has a long orbital period (∝n3), and the radiation lifetime is very long (∝n3-5). At the same time the R. atom is very sensitive to perturbations from external fields in collisions with charged and neutral targets. In recent years, R. atoms have been observed in laboratory and cosmic conditions for n up to ˜1000, which means that the size amounts to about 0.1 mm, ˜106 times that of an atom in the ground state. The scope of this monograph is to familiarize the reader with today's approaches and methods for describing isolated R. atoms and ions, radiative transitions between highly excited states, and photoionization and photorecombination processes. The authors present a number of efficient methods for describing the structure and properties of R. atoms and calculating processes of collisions with neutral and charged particles as well as spectral-line broadening and shift of Rydberg atomic series in gases, cool and hot plasmas in laboratories and in astrophysical sources. Particular attention is paid to a comparison of theoretical results with available experimental data. The book contains 9 chapters. Chapter 1 gives an introduction to the basic properties of R. atoms (ions), Chapter 2 is devoted to an account of general methods describing an isolated Rydberg atom. Chapter 3 is focussed on the recent achievements in calculations of form factors and dipole matrix elements of different types of bound-bound and bound-free radiative transitions. Chapter 4 concentrates on the formulation of basic theoretical methods and physical approaches to collisions involving R. atoms. Chapters 5 to 8 contain a systematic description of major directions and modern techniques in the collision theory of R. atoms and ions with atoms, molecules, electrons, and ions. Finally, Chapter 9 deals with the spectral-line broadening and shift of R. atomic series induced by collisions with neutral and charged particles. A subject index of four pages and 250 references are given. This monograph will be a basic tool and reference for all scientists working in the fields of plasma physics, spectroscopy, physics of electronic and atomic collisions, as well as astrophysics, radio astronomy, and space physics.

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 the Institute of Physics. The support from the IOPCS staff made this publication possible. The 8th AISAMP was sponsored primarily by the University of Western Australia and Curtin University of Technology, both in Perth, Western Australia, and by Journal of Physics: Conference Series. Support was also received from the International Council of Science, ICSU. Guidance and active participation from colleagues, particularly from the University of Western Australia, and Curtin University, and from the Australian National University and Melbourne University were sources of strength for the actual organization of the conference. Dr Elena Semidelova receives special thanks for her organizing abilities. We hope that this issue of Journal of Physics: Conference Series will be referenced widely and that it will strengthen ties between all scientists and their countries. Evan Bieske, Stephen Buckman and Jim F Williams Guest Editors

Faculty Member for Research in an Undergraduate Institution Prize Talk: Research and Teaching through high-precision spectroscopy of heavy atoms

NASA Astrophysics Data System (ADS)

Majumder, Tiku

2017-04-01

In recent decades, substantial experimental effort has centered on heavy (high-Z) atomic and molecular systems for atomic-physics-based tests of standard model physics, through (for example) measurements of atomic parity nonconservation and searches for permanent electric dipole moments. In all of this work, a crucial role is played by atomic theorists, whose accurate wave function calculations are essential in connecting experimental observables to tests of relevant fundamental physics parameters. At Williams College, with essential contributions from dozens of undergraduate students, we have pursued a series of precise atomic structure measurements in heavy metal atoms such as thallium, indium, and lead. These include measurements of hyperfine structure, transition amplitudes, and atomic polarizability. This work, involving diode lasers, heated vapor cells, and an atomic beam apparatus, has both tested the accuracy and helped guide the refinement of new atomic theory calculations. I will discuss a number of our recent experimental results, emphasizing the role played by students and the opportunities that have been afforded for research-training in this undergraduate environment. Work supported by Research Corporation, the NIST Precision Measurement Grants program, and the National Science Foundation.

Opportunities for Maturing Precision Metrology with Ultracold Gas Studies Aboard the ISS

NASA Astrophysics Data System (ADS)

Williams, Jason; D'Incao, Jose

2017-04-01

Precision atom interferometers (AI) in space are expected to become an enabling technology for future fundamental physics research, with proposals including unprecedented tests of the validity of the weak equivalence principle, measurements of the fine structure and gravitational constants, and detection of gravity waves and dark matter/dark energy. We will discuss our preparation at JPL to use NASA's Cold Atom Lab facility (CAL) to mature the technology of precision, space-based, AIs. The focus of our flight project is three-fold: a) study the controlled dynamics of heteronuclear Feshbach molecules, at temperatures of nano-Kelvins or below, as a means to overcome uncontrolled density-profile-dependent shifts in differential AIs, b) demonstrate unprecedented atom-photon coherence times with spatially constrained AIs, c) use the imaging capabilities of CAL to detect and analyze spatial fringe patterns written onto the clouds after AI and thereby measure the rotational noise of the ISS. The impact from this work, and potential for follow-on studies, will also be reviewed in the context of future space-based fundamental physics missions. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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-dimensional materials with fundamentally different electronic and physical properties. Specifically, we focus on recent studies of the addition of atomic hydrogen, fluorine, and oxygen to the basal plane of graphene. In each of these reactions a high energy, activating step initiates the process, breaking the local π structure and distorting the surrounding lattice. Scanning tunneling microscopy experiments reveal that substrate mediated interactions often dominate when the initial binding event occurs. We then compare these substrate effects with the results of theoretical studies that typically assume a vacuum environment. As the surface coverage increases, clusters often form around the initial distortion, and the stoichiometric composition of the saturated end product depends strongly on both the substrate and reactant species. In addition to these chemical and structural observations, we review how covalent modification can extend the range of physical properties that are achievable in two-dimensional materials. PMID:23030800

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,…

Mathematical modeling of chemical composition modification and etching of polymers under the atomic oxygen influence

NASA Astrophysics Data System (ADS)

Chirskaia, Natalia; Novikov, Lev; Voronina, Ekaterina

2016-07-01

Atomic oxygen (AO) of the upper atmosphere is one of the most important space factors that can cause degradation of spacecraft surface. In our previous mathematical model the Monte Carlo method and the "large particles" approximation were used for simulating processes of polymer etching under the influence of AO [1]. The interaction of enlarged AO particles with the polymer was described in terms of probabilities of reactions such as etching of polymer and specular and diffuse scattering of the AO particles on polymer. The effects of atomic oxygen on protected polymers and microfiller containing composites were simulated. The simulation results were in quite good agreement with the results of laboratory experiments on magnetoplasmadynamic accelerator of the oxygen plasma of SINP MSU [2]. In this paper we present a new model that describes the reactions of AO interactions with polymeric materials in more detail. Reactions of formation and further emission of chemical compounds such as CO, CO _{2}, H _{2}O, etc. cause the modification of the chemical composition of the polymer and change the probabilities of its consequent interaction with the AO. The simulation results are compared with the results of previous simulation and with the results of laboratory experiments. The reasons for the differences between the results of natural experiments on spacecraft, laboratory experiments and simulations are discussed. N. Chirskaya, M. Samokhina, Computer modeling of polymer structures degradation under the atomic oxygen exposure, WDS'12 Proceedings of Contributed Papers: Part III - Physics, Matfyzpress Prague, 2012, pp. 30-35. E. Voronina, L. Novikov, V. Chernik, N. Chirskaya, K. Vernigorov, G. Bondarenko, and A. Gaidar, Mathematical and experimental simulation of impact of atomic oxygen of the earth's upper atmosphere on nanostructures and polymer composites, Inorganic Materials: Applied Research, 2012, vol. 3, no. 2, pp. 95-101.

Proposed software system for atomic-structure calculation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, C.F.

1981-07-01

Atomic structure calculations are understood well enough that, at a routine level, an atomic structure software package can be developed. At the Atomic Physics Conference in Riga, 1978 L.V. Chernysheva and M.Y. Amusia of Leningrad University, presented a paper on Software for Atomic Calculations. Their system, called ATOM is based on the Hartree-Fock approximation and correlation is included within the framework of RPAE. Energy level calculations, transition probabilities, photo-ionization cross-sections, electron scattering cross-sections are some of the physical properties that can be evaluated by their system. The MCHF method, together with CI techniques and the Breit-Pauli approximation also provides amore » sound theoretical basis for atomic structure calculations.« less

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…

Physics with Trapped Antihydrogen

NASA Astrophysics Data System (ADS)

Charlton, Michael

2017-04-01

For more than a decade antihydrogen atoms have been formed by mixing antiprotons and positrons held in arrangements of charged particle (Penning) traps. More recently, magnetic minimum neutral atom traps have been superimposed upon the anti-atom production region, promoting the trapping of a small quantity of the antihydrogen yield. We will review these advances, and describe some of the first physics experiments performed on anrtihydrogen including the observation of the two-photon 1S-2S transition, invesigation of the charge neutrailty of the anti-atom and studies of the ground state hyperfine splitting. We will discuss the physics motivations for undertaking these experiments and describe some near-future initiatives.

Kinetics of Fast Atoms in the Terrestrial Atmosphere

NASA Technical Reports Server (NTRS)

Kharchenko, Vasili A.; Dalgarno, A.; Mellott, Mary (Technical Monitor)

2002-01-01

This report summarizes our investigations performed under NASA Grant NAG5-8058. The three-year research supported by the Geospace Sciences SR&T program (Ionospheric, Thermospheric, and Mesospheric Physics) has been designed to investigate fluxes of energetic oxygen and nitrogen atoms in the terrestrial thermosphere. Fast atoms are produced due to absorption of the solar radiation and due to coupling between the ionosphere and the neutral thermospheric gas. We have investigated the impact of hot oxygen and nitrogen atoms on the thermal balance, chemistry and radiation properties of the terrestrial thermosphere. Our calculations have been focused on the accurate quantitative description of the thermalization of O and N energetic atoms in collisions with atom and molecules of the ambient neutral gas. Upward fluxes of oxygen and nitrogen atoms, the rate of atmospheric heating by hot oxygen atoms, and the energy input into translational and rotational-vibrational degrees of atmospheric molecules have been evaluated. Altitude profiles of hot oxygen and nitrogen atoms have been analyzed and compared with available observational data. Energetic oxygen atoms in the terrestrial atmosphere have been investigated for decades, but insufficient information on the kinetics of fast atmospheric atoms has been a main obstacle for the interpretation of observational data and modeling of the hot geocorona. The recent development of accurate computational methods of the collisional kinetics is seen as an important step in the quantitative description of hot atoms in the thermosphere. Modeling of relaxation processes in the terrestrial atmosphere has incorporated data of recent observations, and theoretical predictions have been tested by new laboratory measurements.

Atomistic modeling of crystal-to-amorphous transition and associated kinetics in the Ni-Nb system by molecular dynamics simulations.

PubMed

Dai, X D; Li, J H; Liu, B X

2005-03-17

With the aid of ab initio calculations, an n-body potential of the Ni-Nb system is constructed under the Finnis-Sinclair formalism and the constructed potential is capable of not only reproducing some static physical properties but also revealing the atomistic mechanism of crystal-to-amorphous transition and associated kinetics. With application of the constructed potential, molecular dynamics simulations using the solid solution models reveal that the physical origin of crystal-to-amorphous transition is the crystalline lattice collapsing while the solute atoms are exceeding the critical solid solubilities, which are determined to be 19 atom % Ni and 13 atom % Nb for the Nb- and Ni-based solid solutions, respectively. It follows that an intrinsic glass-forming ability of the Ni-Nb system is within 19-87 atom % Ni, which matches well with that observed in ion beam mixing/solid-state reaction experiments. Simulations using the Nb/Ni/Nb (Ni/Nb/Ni) sandwich models indicate that the amorphous layer at the interfaces grows in a layer-by-layer mode and that, upon dissolving solute atoms, the Ni lattice approaches and exceeds its critical solid solubility faster than the Nb lattice, revealing an asymmetric behavior in growth kinetics. Moreover, an energy diagram is obtained by computing the energetic sequence of the Ni(x)Nb(100)(-)(x) alloy in fcc, bcc, and amorphous structures, respectively, over the entire composition range, and the diagram could serve as a guide for predicting the metastable alloy formation in the Ni-Nb system.

History of Nuclear Fusion Research in Japan

NASA Astrophysics Data System (ADS)

Iguchi, Harukazu; Matsuoka, Keisuke; Kimura, Kazue; Namba, Chusei; Matsuda, Shinzaburo

In the late 1950s just after the atomic energy research was opened worldwide, there was a lively discussion among scientists on the strategy of nuclear fusion research in Japan. Finally, decision was made that fusion research should be started from the basic, namely, research on plasma physics and from cultivation of human resources at universities under the Ministry of Education, Science and Culture (MOE). However, an endorsement was given that construction of an experimental device for fusion research would be approved sooner or later. Studies on toroidal plasma confinement started at Japan Atomic Energy Research Institute (JAERI) under the Science and Technology Agency (STA) in the mid-1960s. Dualistic fusion research framework in Japan was established. This structure has lasted until now. Fusion research activities over the last 50 years are described by the use of a flowchart, which is convenient to glance the historical development of fusion research in Japan.

Formation of Fiber Materials by Pneumatic Spraying of Polymers in Viscous-Flow States

NASA Astrophysics Data System (ADS)

Lysak, I. A.; Malinovskaya, T. D.; Lysak, G. V.; Potekaev, A. I.; Kulagina, V. V.; Tazin, D. I.

2017-02-01

Using a novel ejection spraying unit and relying on new approaches, fibers are formed by the method of pneumatic melt blowing of polycarbonate, polypropylene, and polyethylene terephthalate. The proposed approach is based on the concepts of atomization of the polymer melt flow as a preferential regime for fibermaterial formation. From the analysis of the values of numerical characteristics in the zone of atomization and the physical background of the criteria under study a conclusion is drawn that the essential role in destruction of the jet belongs to the formation of a boundary layer in the melt under the action of friction forces, followed by its separation. An assumption is made on the prevailing action of the separating destruction of the melt jet via the mechanism of `skinning' of the boundary layer of the melt due to a shorter time of its persistence compared to the development of the Kelvin-Helmholtz instability.

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)

Nuclear chemistry. Annual report, 1974

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conzett, H.E.; Edelstein, N.M.; Tsang, C.F.

1975-07-01

The 1974 Nuclear Chemistry Annual Report contains information on research in the following areas: nuclear science (nuclear spectroscopy and radioactivity, nuclear reactions and scattering, nuclear theory); chemical and atomic physics (heavy ion-induced atomic reactions, atomic and molecular spectroscopy, photoelectron spectroscopy and hyperfine interactions); physical, inorganic, and analytical chemistry (x-ray crystallography, physical and inorganic chemistry, geochemistry); and instrumentation. Thesis abstracts, 1974 publication titles, and an author index are also included. Papers having a significant amount of information are listed separately by title. (RWR)

ISOTROPIC INELASTIC COLLISIONS IN A MULTITERM ATOM WITH HYPERFINE STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belluzzi, Luca; Landi Degl’Innocenti, Egidio; Bueno, Javier Trujillo

2015-10-10

A correct modeling of the scattering polarization profiles observed in some spectral lines of diagnostic interest, the sodium doublet being one of the most important examples, requires taking hyperfine structure (HFS) and quantum interference between different J-levels into account. An atomic model suitable for taking these physical ingredients into account is the so-called multiterm atom with HFS. In this work, we introduce and study the transfer and relaxation rates due to isotropic inelastic collisions with electrons, which enter the statistical equilibrium equations (SEE) for the atomic density matrix of this atomic model. Under the hypothesis that the electron–atom interaction ismore » described by a dipolar operator, we provide useful relations between the rates describing the transfer and relaxation of quantum interference between different levels (whose numerical values are in most cases unknown) and the usual rates for the atomic level populations, for which experimental data and/or approximate theoretical expressions are generally available. For the particular case of a two-term atom with HFS, we present an analytical solution of the SEE for the spherical statistical tensors of the upper term, including both radiative and collisional processes, and we derive the expression of the emission coefficient in the four Stokes parameters. Finally, an illustrative application to the Na i D{sub 1} and D{sub 2} lines is presented.« less

Stability of various entanglements in the interaction between two two-level atoms with a quantized field under the influences of several decay sources

NASA Astrophysics Data System (ADS)

Valizadeh, Sh.; Tavassoly, M. K.; Yazdanpanah, N.

2018-02-01

In this paper the interaction between two two-level atoms with a single-mode quantized field is studied. To achieve exact information about the physical properties of the system, one should take into account various sources of dissipation such as photon leakage of cavity, spontaneous emission rate of atoms, internal thermal radiation of cavity and dipole-dipole interaction between the two atoms. In order to achieve the desired goals, we obtain the time evolution of the associated density operator by solving the time-dependent Lindblad equation corresponding to the system. Then, we evaluate the temporal behavior of total population inversion and quantum entanglement between the evolved subsystems, numerically. We clearly show that how the damping parameters affect on the dynamics of considered properties. By analyzing the numerical results, we observe that increasing each of the damping sources leads to faster decay of total population inversion. Also, it is observed that, after starting the interaction, the entanglement between one atom with other parts of the system as well as the entanglement between "atom-atom" subsystem and the "field", tend to some constant values very soon. Moreover, the stable values of entanglement are reduced via increasing the damping factor Γ A (ΓA^{(1)} = ΓA^{(2)} = ΓA ) where ΓA is the spontaneous emission rate of each atom. In addition, we find that by increasing the thermal photons, the entropies (entanglements) tend sooner to some increased stable values. Accordingly, we study the atom-atom entanglement by evaluating the concurrence under the influence of dissipation sources, too. At last, the effects of dissipation sources on the genuine tripartite entanglement between the three subsystems include of two two-level atoms and a quantized field are numerically studied. Due to the important role of stationary entanglement in quantum information processing, our results may provide useful hints for practical protocols which require some appropriate mechanisms to prevent or at least minimize the influence of decoherence phenomenon.

Structural phase transitions of (Bi 1$-$xSb x ) 2(Te 1$-$y Se y) 3 compounds under high pressure and the influence of the atomic radius on the compression processes of tetradymites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Jinggeng; Yu, Zhenhai; Hu, Qingyang

Recently, A 2B 3-type tetradymites have developed into a hot topic in physical and material research fields, where the A and B atoms represent V and VI group elements, respectively. In this study, in situ angle-dispersive X-ray diffraction measurements were performed on Bi 2Te 2Se, BiSbTeSe 2, and Sb 2Te 2Se tetradymites under high pressure. Bi 2Te 2Se transforms from a layered rhombohedral structure (phase I) into 7-fold monoclinic (phase II) and body-centered tetragonal (phase IV) structures at about 8.0 and 14.3 GPa, respectively, without an 8-fold monoclinic structure (phase III) similar to that in Bi 2Te 3. Thus, themore » compression behavior of Bi 2Te 2Se is the same as that of Bi 2Se 3, which could also be obtained from first-principles calculations and in situ high-pressure electrical resistance measurements. Under high pressure, BiSbTeSe 2 and Sb 2Te 2Se undergo similar structural phase transitions to Bi 2Te 2Se, which indicates that the compression process of tellurides can be modulated by doping Se in Te sites. According to these high-pressure investigations of A 2B 3-type tetradymites, the decrease of the B-site atomic radius shrinks the stable pressure range of phase III and expands that of phase II, whereas the decrease of the A-site atomic radius induces a different effect, i.e. expanding the stable pressure range of phase III and shrinking that of phase II. Lastly, the influence of the atomic radius on the compression process of tetradymites is closely related to the chemical composition and the atom arrangement in the quintuple layer.« less

Structural phase transitions of (Bi 1$-$xSb x ) 2(Te 1$-$y Se y) 3 compounds under high pressure and the influence of the atomic radius on the compression processes of tetradymites

DOE PAGES

Zhao, Jinggeng; Yu, Zhenhai; Hu, Qingyang; ...

2016-12-14

Recently, A 2B 3-type tetradymites have developed into a hot topic in physical and material research fields, where the A and B atoms represent V and VI group elements, respectively. In this study, in situ angle-dispersive X-ray diffraction measurements were performed on Bi 2Te 2Se, BiSbTeSe 2, and Sb 2Te 2Se tetradymites under high pressure. Bi 2Te 2Se transforms from a layered rhombohedral structure (phase I) into 7-fold monoclinic (phase II) and body-centered tetragonal (phase IV) structures at about 8.0 and 14.3 GPa, respectively, without an 8-fold monoclinic structure (phase III) similar to that in Bi 2Te 3. Thus, themore » compression behavior of Bi 2Te 2Se is the same as that of Bi 2Se 3, which could also be obtained from first-principles calculations and in situ high-pressure electrical resistance measurements. Under high pressure, BiSbTeSe 2 and Sb 2Te 2Se undergo similar structural phase transitions to Bi 2Te 2Se, which indicates that the compression process of tellurides can be modulated by doping Se in Te sites. According to these high-pressure investigations of A 2B 3-type tetradymites, the decrease of the B-site atomic radius shrinks the stable pressure range of phase III and expands that of phase II, whereas the decrease of the A-site atomic radius induces a different effect, i.e. expanding the stable pressure range of phase III and shrinking that of phase II. Lastly, the influence of the atomic radius on the compression process of tetradymites is closely related to the chemical composition and the atom arrangement in the quintuple layer.« less

Image processing for grazing incidence fast atom diffraction

NASA Astrophysics Data System (ADS)

Debiossac, Maxime; Roncin, Philippe

2016-09-01

Grazing incidence fast atom diffraction (GIFAD, or FAD) has developed as a surface sensitive technique. Compared with thermal energies helium diffraction (TEAS or HAS), GIFAD is less sensitive to thermal decoherence but also more demanding in terms of surface coherence, the mean distance between defects. Such high quality surfaces can be obtained from freshly cleaved crystals or in a molecular beam epitaxy (MBE) chamber where a GIFAD setup has been installed allowing in situ operation. Based on recent publications by Atkinson et al. (2014) and Debiossac et al. (2014), the paper describes in detail the basic steps needed to measure the relative intensities of the diffraction spots. Care is taken to outline the underlying physical assumptions.

Studies on Temperature Dependence of Rubidium Lamp for Atomic Frequency Standard

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosal, Bikash; Banik, Alak; Vats, Vaibhav

2011-10-20

Rb lamp is a very critical component of the Rb atomic clock's Physics Package. The Rb lamp's performance is very sensitive to temperature and its stability. In this paper we discuss the behaviors of Rb Lamp with temperature. The Rb lamp exciter power and temperature of Rb bulb are very important parameters in controlling the performance of the Rb Lamp. It is observed that at temperatures beyond 110 deg. C, the lamp mode changes from the ring to red mode resulting in abnormal broadening of emission lines and self reversal. The results of our studies on spectral analysis of Rbmore » lamp under various operating conditions are reported in the paper.« less

Atomic Bomb: The Story of the Manhattan Project; How nuclear physics became a global geopolitical game-changer

NASA Astrophysics Data System (ADS)

Reed, Bruce Cameron

2015-06-01

This volume, prepared by an acknowledged expert on the Manhattan Project, gives a concise, fast-paced account of all major aspects of the project at a level accessible to an undergraduate college or advanced high-school student familiar with some basic concepts of energy, atomic structure, and isotopes. The text describes the underlying scientific discoveries that made nuclear weapons possible, how the project was organized, the daunting challenges faced and overcome in obtaining fissile uranium and plutonium, and in designing workable bombs, the dramatic Trinity test carried out in the desert of southern New Mexico in July 1945, and the bombings of Hiroshima and Nagasaki.

Quantum dynamics of a BEC interacting with a single-mode quantized field under the influence of a dissipation process: thermal and squeezed vacuum reservoirs

NASA Astrophysics Data System (ADS)

Ghasemian, E.; Tavassoly, M. K.

2017-09-01

In this paper we consider a system consisting of a number of two-level atoms in a Bose-Einstein condensate (BEC) and a single-mode quantized field, which interact with each other in the presence of two different damping sources, i.e. cavity and atomic reservoirs. The reservoirs which we consider here are thermal and squeezed vacuum ones corresponding to field and atom modes. Strictly speaking, by considering both types of reservoirs for each of the atom and field modes, we investigate the quantum dynamics of the interacting bosons in the system. Then, via solving the quantum Langevin equations for such a dissipative BEC system, we obtain analytical expressions for the time dependence of atomic population inversion, mean atom as well as photon number and quadrature squeezing in the field and atom modes. Our investigations demonstrate that for modeling the real physical systems, considering the dissipation effects is essential. Also, numerical calculations which are presented show that the atomic population inversion, the mean number of atoms in the BEC and the photons in the cavity possess damped oscillatory behavior due to the presence of reservoirs. In addition, non-classical squeezing effects in the field quadrature can be observed especially when squeezed vacuum reservoirs are taken into account. As an outstanding property of this model, we may refer to the fact that one can extract the atom-field coupling constant from the frequency of oscillations in the mentioned quantities such as atomic population inversion.

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

Atomically Thin Mesoporous Nanomesh of Graphitic C₃N₄ for High-Efficiency Photocatalytic Hydrogen Evolution.

PubMed

Han, Qing; Wang, Bing; Gao, Jian; Cheng, Zhihua; Zhao, Yang; Zhang, Zhipan; Qu, Liangti

2016-02-23

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

Intracavity Rydberg-atom electromagnetically induced transparency using a high-finesse optical cavity

NASA Astrophysics Data System (ADS)

Sheng, Jiteng; Chao, Yuanxi; Kumar, Santosh; Fan, Haoquan; Sedlacek, Jonathon; Shaffer, James P.

2017-09-01

We present an experimental study of cavity-assisted Rydberg-atom electromagnetically induced transparency (EIT) using a high-finesse optical cavity (F ˜28 000 ). Rydberg atoms are excited via a two-photon transition in a ladder-type EIT configuration. A three-peak structure of the cavity transmission spectrum is observed when Rydberg EIT is generated inside the cavity. The two symmetrically spaced side peaks are caused by bright-state polaritons, while the central peak corresponds to a dark-state polariton. Anticrossing phenomena and the effects of mirror adsorbate electric fields are studied under different experimental conditions. We determine a lower bound on the coherence time for the system of 7.26 ±0.06 μ s , most likely limited by laser dephasing. The cavity-Rydberg EIT system can be useful for single-photon generation using the Rydberg blockade effect, studying many-body physics, and generating novel quantum states among many other applications.

Effects of the local structure dependence of evaporation fields on field evaporation behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Lan; Marquis, Emmanuelle A., E-mail: emarq@umich.edu; Withrow, Travis

2015-12-14

Accurate three dimensional reconstructions of atomic positions and full quantification of the information contained in atom probe microscopy data rely on understanding the physical processes taking place during field evaporation of atoms from needle-shaped specimens. However, the modeling framework for atom probe microscopy has only limited quantitative justification. Building on the continuum field models previously developed, we introduce a more physical approach with the selection of evaporation events based on density functional theory calculations. This model reproduces key features observed experimentally in terms of sequence of evaporation, evaporation maps, and depth resolution, and provides insights into the physical limit formore » spatial resolution.« less

Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacFarlane, Joseph J.; Golovkin, I. E.; Woodruff, P. R.

2009-08-07

This Final Report summarizes work performed under DOE STTR Phase II Grant No. DE-FG02-05ER86258 during the project period from August 2006 to August 2009. The project, “Development of Spectral and Atomic Models for Diagnosing Energetic Particle Characteristics in Fast Ignition Experiments,” was led by Prism Computational Sciences (Madison, WI), and involved collaboration with subcontractors University of Nevada-Reno and Voss Scientific (Albuquerque, NM). In this project, we have: Developed and implemented a multi-dimensional, multi-frequency radiation transport model in the LSP hybrid fluid-PIC (particle-in-cell) code [1,2]. Updated the LSP code to support the use of accurate equation-of-state (EOS) tables generated by Prism’smore » PROPACEOS [3] code to compute more accurate temperatures in high energy density physics (HEDP) plasmas. Updated LSP to support the use of Prism’s multi-frequency opacity tables. Generated equation of state and opacity data for LSP simulations for several materials being used in plasma jet experimental studies. Developed and implemented parallel processing techniques for the radiation physics algorithms in LSP. Benchmarked the new radiation transport and radiation physics algorithms in LSP and compared simulation results with analytic solutions and results from numerical radiation-hydrodynamics calculations. Performed simulations using Prism radiation physics codes to address issues related to radiative cooling and ionization dynamics in plasma jet experiments. Performed simulations to study the effects of radiation transport and radiation losses due to electrode contaminants in plasma jet experiments. Updated the LSP code to generate output using NetCDF to provide a better, more flexible interface to SPECT3D [4] in order to post-process LSP output. Updated the SPECT3D code to better support the post-processing of large-scale 2-D and 3-D datasets generated by simulation codes such as LSP. Updated atomic physics modeling to provide for more comprehensive and accurate atomic databases that feed into the radiation physics modeling (spectral simulations and opacity tables). Developed polarization spectroscopy modeling techniques suitable for diagnosing energetic particle characteristics in HEDP experiments. A description of these items is provided in this report. The above efforts lay the groundwork for utilizing the LSP and SPECT3D codes in providing simulation support for DOE-sponsored HEDP experiments, such as plasma jet and fast ignition physics experiments. We believe that taken together, the LSP and SPECT3D codes have unique capabilities for advancing our understanding of the physics of these HEDP plasmas. Based on conversations early in this project with our DOE program manager, Dr. Francis Thio, our efforts emphasized developing radiation physics and atomic modeling capabilities that can be utilized in the LSP PIC code, and performing radiation physics studies for plasma jets. A relatively minor component focused on the development of methods to diagnose energetic particle characteristics in short-pulse laser experiments related to fast ignition physics. The period of performance for the grant was extended by one year to August 2009 with a one-year no-cost extension, at the request of subcontractor University of Nevada-Reno.« less

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

Studies of Highly Excited Atoms.

DTIC Science & Technology

1986-04-02

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A Framework to Learn Physics from Atomically Resolved Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlcek, L.; Maksov, A.; Pan, M.

Here, we present a generalized framework for physics extraction, i.e., knowledge, from atomically resolved images, and show its utility by applying it to a model system of segregation of chalcogen atoms in an FeSe 0.45Te 0.55 superconductor system. We emphasize that the framework can be used for any imaging data for which a generative physical model exists. Consider that a generative physical model can produce a very large number of configurations, not all of which are observable. By applying a microscope function to a sub-set of this generated data, we form a simulated dataset on which statistics can be computed.

In situ growth of Ag nanoparticles on α-Ag2WO4 under electron irradiation: probing the physical principles

NASA Astrophysics Data System (ADS)

San-Miguel, Miguel A.; da Silva, Edison Z.; Zannetti, Sonia M.; Cilense, Mario; Fabbro, Maria T.; Gracia, Lourdes; Andrés, Juan; Longo, Elson

2016-06-01

Exploiting the plasmonic behavior of Ag nanoparticles grown on α-Ag2WO4 is a widely employed strategy to produce efficient photocatalysts, ozone sensors, and bactericides. However, a description of the atomic and electronic structure of the semiconductor sites irradiated by electrons is still not available. Such a description is of great importance to understand the mechanisms underlying these physical processes and to improve the design of silver nanoparticles to enhance their activities. Motivated by this, we studied the growth of silver nanoparticles to investigate this novel class of phenomena using both transmission electron microscopy and field emission scanning electron microscopy. A theoretical framework based on density functional theory calculations (DFT), together with experimental analysis and measurements, were developed to examine the changes in the local geometrical and electronic structure of the materials. The physical principles for the formation of Ag nanoparticles on α-Ag2WO4 by electron beam irradiation are described. Quantum mechanical calculations based on DFT show that the (001) of α-Ag2WO4 displays Ag atoms with different coordination numbers. Some of them are able to diffuse out of the surface with a very low energy barrier (less than 0.1 eV), thus, initiating the growth of metallic Ag nanostructures and leaving Ag vacancies in the bulk material. These processes increase the structural disorder of α-Ag2WO4 as well as its electrical resistance as observed in the experimental measurements.

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…

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…

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, Molecular and Optical Physics. We received extensive support from the Journal of Physics: Conference Series staff; Graham Douglas, in particular, has been of tremendous help. The 7th AISAMP was very well attended and was sponsored primarily by the host Indian Institute of Technology, Madras (Chennai), the Board of Research in Nuclear Sciences, (Department of Atomic Energy, Government of India), the Department of Science and Technology, (Government of India), and the Asian Office of Aerospace Research and Development (AOARD) of the US Air Force. There was support from various quarters—each was invaluable and added to the success of the 7th AISAMP. We are very grateful to all the sponsors. It is superfluous to add that guidance and active participation from several colleagues within the host Institute was the primary source of strength for the actual organization of the conference and the multitude of arrangements for the organization came from the young graduate students at the IIT-Madras. We hope that this volume of Journal of Physics: Conference Series will be referenced widely and that it will strengthen ties between various countries in the region in and around Asia, and also of course to all scientists in this field the world over. Pranawa C Deshmukh, Purushottam Chakraborty and Jim F Williams Editors Conference photograph

Ionization potential depression in an atomic-solid-plasma picture

NASA Astrophysics Data System (ADS)

Rosmej, F. B.

2018-05-01

Exotic solid density matter such as heated hollow crystals allow extended material studies while their physical properties and models such as the famous ionization potential depression are presently under renewed controversial discussion. Here we develop an atomic-solid-plasma (ASP) model that permits ionization potential depression studies also for single and multiple core hole states. Numerical calculations show very good agreement with recently available data not only in absolute values but also for Z-scaled properties while currently employed methods fail. For much above solid density compression, the ASP model predicts increased K-edge energies that are related to a Fermi surface rising. This is in good agreement with recent quantum molecular dynamics simulations. For hot dense matter a quantum number dependent optical electron finite temperature ion sphere model is developed that fits well with line shift and line disappearance data from dense laser produced plasma experiments. Finally, the physical transparency of the ASP picture allows a critical discussion of current methods.

Rayleigh scattering in an emitter-nanofiber-coupling system

NASA Astrophysics Data System (ADS)

Tang, Shui-Jing; Gao, Fei; Xu, Da; Li, Yan; Gong, Qihuang; Xiao, Yun-Feng

2017-04-01

Scattering is a general process in both fundamental and applied physics. In this paper, we investigate Rayleigh scattering of a solid-state-emitter coupled to a nanofiber, by S -matrix-like theory in k -space description. Under this model, both Rayleigh scattering and dipole interaction are studied between a two-level artificial atom embedded in a nanocrystal and fiber modes (guided and radiation modes). It is found that Rayleigh scattering plays a critical role in the transport properties and quantum statistics of photons. On the one hand, Rayleigh scattering produces the transparency in the optical transmitted field of the nanofiber, accompanied by the change of atomic phase, population, and frequency shift. On the other hand, the interference between two kinds of scattering fields by Rayleigh scattering and dipole transition modifies the photon statistics (second-order autocorrelation function) of output fields, showing a strong wavelength dependence. This study provides guidance for the solid-state emitter acting as a single-photon source and can be extended to explore the scattering effect in many-body physics.

Failure of Local Thermal Equilibrium in Quantum Friction

NASA Astrophysics Data System (ADS)

Intravaia, F.; Behunin, R. O.; Henkel, C.; Busch, K.; Dalvit, D. A. R.

2016-09-01

Recent progress in manipulating atomic and condensed matter systems has instigated a surge of interest in nonequilibrium physics, including many-body dynamics of trapped ultracold atoms and ions, near-field radiative heat transfer, and quantum friction. Under most circumstances the complexity of such nonequilibrium systems requires a number of approximations to make theoretical descriptions tractable. In particular, it is often assumed that spatially separated components of a system thermalize with their immediate surroundings, although the global state of the system is out of equilibrium. This powerful assumption reduces the complexity of nonequilibrium systems to the local application of well-founded equilibrium concepts. While this technique appears to be consistent for the description of some phenomena, we show that it fails for quantum friction by underestimating by approximately 80% the magnitude of the drag force. Our results show that the correlations among the components of driven, but steady-state, quantum systems invalidate the assumption of local thermal equilibrium, calling for a critical reexamination of this approach for describing the physics of nonequilibrium systems.

Editorial

NASA Astrophysics Data System (ADS)

Rudolph, Dirk; Elding, Lars-Ivar; Fahlander, Claes; Åberg, Sven

2016-12-01

Science often develops most vigorously through challenging studies of extreme phenomena. Superheavy elements fall into such a category. What is the heaviest element that can exist in Nature? Driven by the continued search for an anticipated "island of stability" of superheavy atomic nuclei and the understanding of their underlying nuclear (in)stability and atomic structure hence chemical properties, the past decades have seen a tremendous progress in experimental ingenuity and theoretical methodology to study and characterize superheavy elements. Therefore, we are very grateful that the Nobel Foundation [1] approved and, jointly with the Knut and Alice Wallenberg Foundation [2], provided the financial resources to organize and conduct the Nobel Symposium NS160, entitled Chemistry and Physics of Heavy and Superheavy Elements. These symposia "are devoted to areas of science where breakthroughs are occurring or deal with other topics of primary cultural or social significance" [1]. About three symposia are held each year, roughly every fourth symposium promotes a topic in physics as primary research area, and from about every third symposium a contemporary Nobel Price is being awarded.

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.

Tripartite entanglement dynamics and entropic squeezing of a three-level atom interacting with a bimodal cavity field

NASA Astrophysics Data System (ADS)

Faghihi, M. J.; Tavassoly, M. K.; Bagheri Harouni, M.

2014-04-01

In this paper, we study the interaction between a Λ-type three-level atom and two quantized electromagnetic fields which are simultaneously injected in a bichromatic cavity surrounded by a Kerr medium in the presence of field-field interaction (parametric down conversion) and detuning parameters. By applying a canonical transformation, the introduced model is reduced to a well-known form of the generalized Jaynes-Cummings model. Under particular initial conditions which may be prepared for the atom and the field, the time evolution of the state vector of the entire system is analytically evaluated. Then, the dynamics of the atom is studied through the evolution of the atomic population inversion. In addition, two different measures of entanglement between the tripartite system (three entities make the system: two field modes and one atom), i.e., von Neumann and linear entropy are investigated. Also, two kinds of entropic uncertainty relations, from which entropy squeezing can be obtained, are discussed. In each case, the influences of the detuning parameters and Kerr medium on the above nonclassicality features are analyzed in detail via numerical results. It is illustrated that the amount of the above-mentioned physical phenomena can be tuned by choosing the evolved parameters, appropriately.

Mass loss of shuttle space suit orthofabric under simulated ionospheric atomic oxygen bombardment

NASA Technical Reports Server (NTRS)

Miller, W. L.

1985-01-01

Many polymeric materials used for thermal protection and insulation on spacecraft degrade significantly under prolonged bombardment by ionospheric atomic oxygen. The covering fabric of the multilayered shuttle space suit is composed of a loose weave of GORE-TEX fibers, Nomex and Kevlar-29, which are all polymeric materials. The complete evaluation of suit fabric degradation from ionospheric atomic oxygen is of importance in reevaluating suit lifetime and inspection procedures. The mass loss and visible physical changes of each test sample was determined. Kapton control samples and data from previous asher and flight tests were used to scale the results to reflect ionospheric conditions at about 220 km altitude. It is predicted that the orthofabric loses mass in the ionosphere at a rate of about 66% of the original orthofabric mass/yr. The outer layer of the two-layer orthofabric test samples shows few easily visible signs of degradation, even when observed at 440X. It is concluded that the orthofabric could suffer significant loss of performance after much less than a year of total exposure time, while the degradation might be undetectable in post flight visual examinations of space suits.

The application of quasi-steady approximation in atomic kinetics in simulation of hohlraum radiation drive

NASA Astrophysics Data System (ADS)

Ren, Guoli; Pei, Wenbing; Lan, Ke; Li, Xin; Hohlraum Physics Team

2014-10-01

In current routine 2D simulation of hohlraum physics, we adopt the principal-quantum-number (n-level) average atom model (AAM) in NLTE plasma description. The more sophisticated atomic kinetics description is better choice, but the in-line calculation consumes much more resource. By distinguishing the much more fast bound-bound atomic processes from the relative slow bound-free atomic processes, we found a method to built up a bound electron distribution (n-level or nl-level) using in-line n-level calculated plasma condition (such as temperature, density, average ionization degree). We name this method ``quasi-steady approximation.'' Using this method and the plasma condition calculated under n-level, we re-build the nl-level bound electron distribution (Pnl), and acquire a new hohlraum radiative drive by post-processing. Comparison with the n-level post-processed hohlraum drive shows that we get an almost identical radiation flux but with more-detailed frequency-dependant structures. Also we use this method in the benchmark gold sphere experiment, the constructed nl-level radiation drive resembles the experimental results and DCA results, while the n-level raditation does not.

Breaking Quantum and Thermal Limits on Precision Measurements

NASA Astrophysics Data System (ADS)

Thompson, James K.

2016-05-01

I will give an overview of our efforts to use correlations and entanglement between many atoms to overcome quantum and thermal limits on precision measurements. In the first portion of my talk, I will present a path toward a 10000 times reduced sensitivity to the thermal mirror motion that limits the linewidth of today's best lasers. By utilizing narrow atomic transitions, the laser's phase information is primarily stored in the atomic gain medium rather than in the vibration-sensitive cavity field. To this end, I will present the first observation of lasing based on the mHz linewidth optical-clock transition in a laser-cooled ensemble of strontium atoms. In the second portion of my talk, I will describe how we use collective measurements to surpass the standard quantum limit on phase estimation 1 /√{ N} for N unentangled atoms. We achieve a directly observed reduction in phase variance relative to the standard quantum limit of as much as 17.7(6) dB. Supported by DARPA QuASAR, NIST, ARO, and NSF PFC. This material is based upon work supported by the National Science Foundation under Grant Number 1125844 Physics Frontier Center.

Captives of Their Fantasies: The German Atomic Bomb Scientists

NASA Astrophysics Data System (ADS)

Klotz, Irving M.

1997-02-01

When the Nazi government collapsed in May, 1945, an Allied intelligence mission took into custody nine of the German scientists who played key roles in the German atomic bomb project. Under great secrecy these men were confined in a large country house, Farm Hall, near Cambridge (England), and their conversations were recorded surreptitiously by hidden microphones in every room. The transcripts were kept TOP SECRET for 47 years and were finally released recently. They give fascinating insights into the personalities of the guests and invaluable information on what the Germans really understood about the physics and chemistry of a nuclear reactor and an atomic bomb. The Farm Hall transcripts clearly establish that (a) the Germans on August 6, 1945 did not believe that the Allies had exploded an atomic bomb over Hiroshima that day; (b) they never succeeded in constructing a self-sustaining nuclear reactor; (c) they were confused about the differences between an atomic bomb and a reactor; (d) they did not know how to correctly calculate the critical mass of a bomb; (e) they thought that "plutonium" was probably element 91. The Farm Hall transcripts contradict the self-serving and sensationalist writings about German efforts that have appeared during the past fifty years.

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.

Sixteenth International Conference on the physics of electronic and atomic collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalgarno, A.; Freund, R.S.; Lubell, M.S.

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.

Spectroscopic determinations of carbon fluxes, sources, and shielding in the DIII-D divertors

NASA Astrophysics Data System (ADS)

Isler, R. C.; Colchin, R. J.; Brooks, N. H.; Evans, T. E.; West, W. P.; Whyte, D. G.

2001-10-01

The most important mechanisms for eroding plasma-facing components (PFCs) and introducing carbon into tokamak divertors are believed to be physical sputtering, chemical sputtering, sublimation, and radiation enhance sublimation (RES). The relative importance of these processes has been investigated by analyzing the spectral emission rates and the effective temperatures of CI, CD, and C2 under several operating conditions in the DIII-D tokamak [Plasma Physics Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159; Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque (Institute of Electrical and Electronic Engineers, Piscataway, 1999), p. 515]. Discrimination of chemical sputtering from physical sputtering is accomplished by quantitatively relating the fraction of CI influxes expected from dissociation of hydrocarbons to the measured CD and C2 influxes. Characteristics of sublimation are studied from carbon test samples heated to surface temperatures exceeding 2000 K. The shielding efficiency of carbon produced at the divertor target is assessed from comparison of fluxes of neutral atoms and ions; approximately 95% of the primary influx appears to be redeposited before being transported far enough upstream to fuel the core plasma.

Spectroscopic determinations of carbon fluxes, sources, and shielding in the DIII-D divertors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isler, R. C.; Colchin, R. J.; Brooks, N. H.

2001-10-01

The most important mechanisms for eroding plasma-facing components (PFCs) and introducing carbon into tokamak divertors are believed to be physical sputtering, chemical sputtering, sublimation, and radiation enhance sublimation (RES). The relative importance of these processes has been investigated by analyzing the spectral emission rates and the effective temperatures of CI, CD, and C{sub 2} under several operating conditions in the DIII-D tokamak [Plasma Physics Controlled Nuclear Fusion Research, 1986 (International Atomic Energy Agency, Vienna, 1987), Vol. I, p. 159; Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque (Institute of Electrical and Electronic Engineers, Piscataway, 1999), p. 515]. Discriminationmore » of chemical sputtering from physical sputtering is accomplished by quantitatively relating the fraction of CI influxes expected from dissociation of hydrocarbons to the measured CD and C{sub 2} influxes. Characteristics of sublimation are studied from carbon test samples heated to surface temperatures exceeding 2000 K. The shielding efficiency of carbon produced at the divertor target is assessed from comparison of fluxes of neutral atoms and ions; approximately 95% of the primary influx appears to be redeposited before being transported far enough upstream to fuel the core plasma.« less

Precision Tests of the Electroweak Interaction using Trapped Atoms and Ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melconian, Daniel George

The objective of the proposed research is to study fundamental aspects of the electroweak interaction via precision measurements in beta decay to test our current understanding of fundamental particles and forces as contained in the so-called "Standard Model" of particle physics. By comparing elegant experiments to rigorous theoretical predictions, we will either confirm the Standard Model to a higher degree and rule out models which seek to extend it, or find evidence of new physics and help guide theorists in developing the New Standard Model. The use of ion and neutral atom traps at radioactive ion beam facilities has openedmore » up a new vista in precision low-energy nuclear physics experiments. Traps provide an ideal source of decaying atoms: they can be extremely cold (~1 mK); they are compact (~1 mm^3); and perhaps most importantly, the daughter particles escape with negligible distortions to their momenta in a scattering-free, open environment. The project is taking advantage of these technologies and applying them to precision beta-decay studies at radioactive beam facilities. The program consists of two complementary efforts: 1) Ion traps are an extremely versatile tool for purifying, cooling and bunching low-energy beams of short-lived nuclei. A large-bore (210~mm) superconducting 7-Tesla solenoid is at the heart of a Penning trap system for which there is a dedicated beamline at T-REX, the upgraded radioactive beam facility at the Cyclotron Institute, Texas A&M University. In addition to providing a general-purpose decay station, the flagship program for this system is measuring the ft-values and beta-neutrino correlation parameters from isospin T=2 superallowed beta-delayed proton decays, complimenting and expanding the already strong program in fundamental interactions at the Institute. 2) A magneto-optical trap is being used at the TRIUMF Neutral Atom Trap facility to observe the (un)polarized angular distribution parameters of isotopes of potassium. We are able to highly polarize laser-cooled atoms and observe their decay with unprecedented precision. The correlation of the daughter beta particle with the initial nuclear spin as well as other correlations are sensitive to physics beyond the Standard Model. Both of these cutting-edge and exciting research efforts will test our understanding of the fundamental symmetries underlying our current theory of electroweak interactions. Complementary to high-energy collider experiments, these low-energy nuclear physics "table-top" experiments will search for new particles and interactions which are not already described by the Standard Model of particle physics. The value of this research is recognized to be cross-disciplinary, exciting and potentially revolutionary in our understanding of nature's fundamental interactions. Accordingly, it has been endorsed by the recent (2007) Nuclear Science Advisory Committee's Long Range Plan as part of their recommendation for a "New Standard Model Initiative." In addition to the near-term benefits of scholarly publications and visibility through description of this work at international conferences, an important benefit of this research program is the training of new, young and enthusiastic nuclear physicists. Participants in this demanding and rewarding field develop a very strong background in physics with experience in a range of its subfields since we use atomic techniques and apply them to a nuclear physics experiment which in the end tests the theories of high-energy physics.« less

A haptic model of vibration modes in spherical geometry and its application in atomic physics, nuclear physics and beyond

NASA Astrophysics Data System (ADS)

Ubben, Malte; Heusler, Stefan

2018-07-01

Vibration modes in spherical geometry can be classified based on the number and position of nodal planes. However, the geometry of these planes is non-trivial and cannot be easily displayed in two dimensions. We present 3D-printed models of those vibration modes, enabling a haptic approach for understanding essential features of bound states in quantum physics and beyond. In particular, when applied to atomic physics, atomic orbitals are obtained in a natural manner. Applied to nuclear physics, the same patterns of vibration modes emerge as cornerstone for the nuclear shell model. These applications of the very same model in a range of more than 5 orders of magnitude in length scales leads to a general discussion of the applicability and limits of validity of physical models in general.

Modeling of low-temperature plasmas generated using laser-induced breakdown spectroscopy: the ChemCam diagnostic tool on the Mars Science Laboratory Rover

NASA Astrophysics Data System (ADS)

Colgan, James

2016-05-01

We report on efforts to model the low-temperature plasmas generated using laser-induced breakdown spectroscopy (LIBS). LIBS is a minimally invasive technique that can quickly and efficiently determine the elemental composition of a target and is employed in an extremely wide range of applications due to its ease of use and fast turnaround. In particular, LIBS is the diagnostic tool used by the ChemCam instrument on the Mars Science Laboratory rover Curiosity. In this talk, we report on the use of the Los Alamos plasma modeling code ATOMIC to simulate LIBS plasmas, which are typically at temperatures of order 1 eV and electron densities of order 10 16 - 17 cm-3. At such conditions, these plasmas are usually in local-thermodynamic equilibrium (LTE) and normally contain neutral and singly ionized species only, which then requires that modeling must use accurate atomic structure data for the element under investigation. Since LIBS devices are often employed in a very wide range of applications, it is therefore desirable to have accurate data for most of the elements in the periodic table, ideally including actinides. Here, we discuss some recent applications of our modeling using ATOMIC that have explored the plasma physics aspects of LIBS generated plasmas, and in particular discuss the modeling of a plasma formed from a basalt sample used as a ChemCam standard1. We also highlight some of the more general atomic physics challenges that are encountered when attempting to model low-temperature plasmas. The Los Alamos National Laboratory is operated by Los Alamos National Security, LLC for the National Nuclear Security Administration of the U.S. Department of Energy under Contract No. DE-AC5206NA25396. Work performed in conjunction with D. P. Kilcrease, H. M. Johns, E. J. Judge, J. E. Barefield, R. C. Wiens, S. M. Clegg.

FROM THE HISTORY OF PHYSICS: The nuclear shield in the 'thirty-year war' of physicists against ignorant criticism of modern physical theories

NASA Astrophysics Data System (ADS)

Vizgin, Vladimir P.

1999-12-01

This article deals with the almost 'thirty-year war' led by physicists against the authorities' incompetent philosophical and ideological interference with science. The 'war' is shown to have been related to the history of Soviet nuclear weapons. Theoretical milestones of 20th century physics, to wit, theory of relativity and quantum mechanics, suffered endless 'attacks on philosophical grounds'. The theories were proclaimed idealistic as well as unduly abstract and out of touch with practice; their authors and followers were labelled 'physical idealists', and later, in the 1940s and 1950s, even 'cosmopolitans without kith or kin'. Meanwhile, quantum and relativistic theories, as is widely known, had become the basis of nuclear physics and of the means of studying the atomic nucleus (charged particle accelerators, for instance). The two theories thus served, to a great extent, as a basis for both peaceful and military uses of nuclear energy, made possible by the discovery of uranium nuclear fission under the action of neutrons. In the first part, the article recounts how prominent physicists led the way to resisting philosophical and ideological pressure and standing up for relativity, quantum theories and nuclear physics, thus enabling the launch of the atomic project. The second part contains extensive material proving the point that physicists effectively used the 'nuclear shield' in the 1940s and 1950s against the 'philosophical-cosmopolitan' pressure, indeed saving physics from a tragic fate as that of biology at the Academy of Agricultural Sciences (VASKhNIL) session in 1948.

Interference, focusing and excitation of ultracold atoms

NASA Astrophysics Data System (ADS)

Kandes, M. C.; Fahy, B. M.; Williams, S. R.; Tally, C. H., IV; Bromley, M. W. J.

2011-05-01

One of the pressing technological challenges in atomic physics is to go orders-of-magnitude beyond the limits of photon-based optics by harnessing the wave-nature of dilute clouds of ultracold atoms. We have developed parallelised algorithms to perform numerical calculations of the Gross-Pitaevskii equation in up to three dimensions and with up to three components to simulate Bose-Einstein condensates. A wide-ranging array of the physics associated with atom optics-based systems will be presented including BEC-based Sagnac interferometry in circular waveguides, the focusing of BECs using Laguerre-Gauss beams, and the interactions between BECs and Ince-Gaussian laser beams and their potential applications. One of the pressing technological challenges in atomic physics is to go orders-of-magnitude beyond the limits of photon-based optics by harnessing the wave-nature of dilute clouds of ultracold atoms. We have developed parallelised algorithms to perform numerical calculations of the Gross-Pitaevskii equation in up to three dimensions and with up to three components to simulate Bose-Einstein condensates. A wide-ranging array of the physics associated with atom optics-based systems will be presented including BEC-based Sagnac interferometry in circular waveguides, the focusing of BECs using Laguerre-Gauss beams, and the interactions between BECs and Ince-Gaussian laser beams and their potential applications. Performed on computational resources via NSF grants PHY-0970127, CHE-0947087 and DMS-0923278.

Self-organized pattern formation at organic-inorganic interfaces during deposition: Experiment versus modeling

NASA Astrophysics Data System (ADS)

Szillat, F.; Mayr, S. G.

2011-09-01

Self-organized pattern formation during physical vapor deposition of organic materials onto rough inorganic substrates is characterized by a complex morphological evolution as a function of film thickness. We employ a combined experimental-theoretical study using atomic force microscopy and numerically solved continuum rate equations to address morphological evolution in the model system: poly(bisphenol A carbonate) on polycrystalline Cu. As the key ingredients for pattern formation, (i) curvature and interface potential driven surface diffusion, (ii) deposition noise, and (iii) interface boundary effects are identified. Good agreement of experiments and theory, fitting only the Hamaker constant and diffusivity within narrow physical parameter windows, corroborates the underlying physics and paves the way for computer-assisted interface engineering.

Control and Transfer of Entanglement between Two Atoms Driven by Classical Fields under Dressed-State Representation

NASA Astrophysics Data System (ADS)

Liao, Qing-Hong; Zhang, Qi; Xu, Juan; Yan, Qiu-Rong; Liu, Ye; Chen, An

2016-06-01

We have studied the dynamics and transfer of the entanglement of the two identical atoms simultaneously interacting with vacuum field by employing the dressed-state representation. The two atoms are driven by classical fields. The influence of the initial entanglement degree of two atoms, the coupling strength between the atom and the classical field and the detuning between the atomic transition frequency and the frequency of classical field on the entanglement and atomic linear entropy is discussed. The initial entanglement of the two atoms can be transferred into the entanglement between the atom and cavity field when the dissipation is neglected. The maximally entangled state between the atoms and cavity field can be obtained under some certain conditions. The time of disentanglement of two atoms can be controlled and manipulated by adjusting the detuning and classical driving fields. Moreover, the larger the cavity decay rate is, the more quickly the entanglement of the two atoms decays. Supported by National Natural Science Foundation of China under Grant Nos. 11247213, 61368002, 11304010, 11264030, 61168001, China Postdoctoral Science Foundation under Grant No. 2013M531558, Jiangxi Postdoctoral Research Project under Grant No. 2013KY33, the Natural Science Foundation of Jiangxi Province under Grant No. 20142BAB217001, the Foundation for Young Scientists of Jiangxi Province (Jinggang Star) under Grant No. 20122BCB23002, the Research Foundation of the Education Department of Jiangxi Province under Grant Nos. GJJ13051, GJJ13057, and the Graduate Innovation Special Fund of Nanchang University under Grant No. cx2015137

Transverse effects in nonlinear optics: Toward the photon superfluid

NASA Astrophysics Data System (ADS)

McCormick, Colin Fraser

Nonlinear optics displays a wealth of transverse effects. These effects are particularly rich in the presence of an optical cavity. Many considerations suggest that in a Kerr nonlinear cavity a new state of light known as a "photon superfluid" can form, with strong analogies to atomic superfluids. The conditions for the formation of the photon superfluid include requirements on the cavity, input light fields and the nonlinear medium as well as various timescales. The most favorable candidate nonlinear medium for observing the photon super-fluid is an atomic vapor. With a strong and fast Kerr effect, atomic vapors also have the advantage of a Kerr coefficient that is tunable in both magnitude and sign. A series of z-scan experiments in far-detuned atomic rubidium vapor is reported, measuring the Kerr coefficient and determining its functional dependence on detuning to be that of a Doppler-broadened two-level model with adiabatic following of the electric field by the atom pseudomoment. Saturation effects are found to be important. Z-scan measurements for detunings within the Doppler profile are shown to agree well with numerical simulations based on the Doppler-broadened model. Agreement between absorptive and refractive non-linear coefficients is evidence of the Kramers-Kronig relations at work, even in this nonlinear system. The formation of the photon superfluid is discussed and the calculation of a new process, nearly collinear four-wave mixing, is presented. This process is essentially an inverse beam filamentation that is likely to be the underlying physical mechanism for transverse cooling and condensation of photons in a nonlinear optical cavity. Nearly collinear four-wave mixing may also be related to phenomena in general nonlinear physics, including modulation instability and Fermi-Pasta-Ulam recurrence.

The Materials Chemistry of Atomic Oxygen with Applications to Anisotropic Etching of Submicron Structures in Microelectronics and the Surface Chemistry Engineering of Porous Solids

NASA Technical Reports Server (NTRS)

Koontz, Steve L.; Leger, Lubert J.; Wu, Corina; Cross, Jon B.; Jurgensen, Charles W.

1994-01-01

Neutral atomic oxygen is the most abundant component of the ionospheric plasma in the low Earth orbit environment (LEO; 200 to 700 kilometers altitude) and can produce significant degradation of some spacecraft materials. In order to produce a more complete understanding of the materials chemistry of atomic oxygen, the chemistry and physics of O-atom interactions with materials were determined in three radically different environments: (1) The Space Shuttle cargo bay in low Earth orbit (the EOIM-3 space flight experiment), (2) a high-velocity neutral atom beam system (HVAB) at Los Alamos National Laboratory (LANL), and (3) a microwave-plasma flowing-discharge system at JSC. The Space Shuttle and the high velocity atom beam systems produce atom-surface collision energies ranging from 0.1 to 7 eV (hyperthermal atoms) under high-vacuum conditions, while the flowing discharge system produces a 0.065 eV surface collision energy at a total pressure of 2 Torr. Data obtained in the three different O-atom environments referred to above show that the rate of O-atom reaction with polymeric materials is strongly dependent on atom kinetic energy, obeying a reactive scattering law which suggests that atom kinetic energy is directly available for overcoming activation barriers in the reaction. General relationships between polymer reactivity with O atoms and polymer composition and molecular structure have been determined. In addition, vacuum ultraviolet photochemical effects have been shown to dominate the reaction of O atoms with fluorocarbon polymers. Finally, studies of the materials chemistry of O atoms have produced results which may be of interest to technologists outside the aerospace industry. Atomic oxygen 'spin-off' or 'dual use' technologies in the areas of anisotropic etching in microelectronic materials and device processing, as well as surface chemistry engineering of porous solid materials are described.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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.

Ambient-temperature diffusion and gettering of Pt atoms in GaN with surface defect region under 60Co gamma or MeV electron irradiation

NASA Astrophysics Data System (ADS)

Hou, Ruixiang; Li, Lei; Fang, Xin; Xie, Ziang; Li, Shuti; Song, Weidong; Huang, Rong; Zhang, Jicai; Huang, Zengli; Li, Qiangjie; Xu, Wanjing; Fu, Engang; Qin, G. G.

2018-01-01

Generally, the diffusion and gettering of impurities in GaN needs high temperature. Calculated with the ambient-temperature extrapolation value of the high temperature diffusivity of Pt atoms in GaN reported in literature, the time required for Pt atoms diffusing 1 nm in GaN at ambient temperature is about 19 years. Therefore, the ambient-temperature diffusion and gettering of Pt atoms in GaN can hardly be observed. In this work, the ambient-temperature diffusion and gettering of Pt atoms in GaN is reported for the first time. It is demonstrated by use of secondary ion mass spectroscopy that in the condition of introducing a defect region on the GaN film surface by plasma, and subsequently, irradiated by 60Co gamma-ray or 3 MeV electrons, the ambient-temperature diffusion and gettering of Pt atoms in GaN can be detected. It is more obvious with larger irradiation dose and higher plasma power. With a similar surface defect region, the ambient-temperature diffusion and gettering of Pt atoms in GaN stimulated by 3 MeV electron irradiation is more marked than that stimulated by gamma irradiation. The physical mechanism of ambient-temperature diffusion and gettering of Pt atoms in a GaN film with a surface defect region stimulated by gamma or MeV electron irradiation is discussed.

A DFT study of the stability of SIAs and small SIA clusters in the vicinity of solute atoms in Fe

NASA Astrophysics Data System (ADS)

Becquart, C. S.; Ngayam Happy, R.; Olsson, P.; Domain, C.

2018-03-01

The energetics, defect volume and magnetic properties of single SIAs and small SIA clusters up to size 6 have been calculated by DFT for different configurations like the parallel 〈110〉 dumbbell, the non parallel 〈110〉 dumbbell and the C15 structure. The most stable configurations of each type have been further analyzed to determine the influence on their stability of various solute atoms (Ti, V, Cr, Mn, Co, Ni, Cu, Mo, W, Pd, Al, Si, P), relevant for steels used under irradiation. The results show that the presence of solute atoms does not change the relative stability order among SIA clusters. The small SIA clusters investigated can bind to both undersized and oversized solutes. Several descriptors have been considered to derive interesting trends from results. It appears that the local atomic volume available for the solute is the main physical quantity governing the binding energy evolution, whatever the solute type (undersized or oversized) and the cluster configuration (size and type).

Theoretical studies of association and dissociation of Feshbach molecules in a microgravity environment

NASA Astrophysics Data System (ADS)

D'Incao, Jose; Williams, Jason

2017-04-01

NASA's Cold Atom Laboratory (CAL) is a multi-user facility scheduled for launch to the ISS in 2017. Our flight experiments with CAL will characterize and mitigate leading-order systematics in dual-atomic-species atom interferometers in microgravity relevant for future fundamental physics missions in space. As part of the initial state preparation for interferometry studies, here, we study the RF association and dissociation of weakly bound heteronuclear Feshbach molecules for expected parameters relevant for the microgravity environment of CAL. This includes temperatures on the pico-Kelvin range and atomic densities as low as 108/cm3. We show that under such conditions, thermal and loss effects can be greatly suppressed, resulting in high efficiency in both association and dissociation of extremely weakly bound Feshbach molecules and allowing for high accuracy determination coherent properties of such processes. In addition we study the possibility to implement delta-kick cooling techniques for weakly bound heteronuclear molecules and explore numerically other methods for molecular association and dissociation including the effects of three-body interactions. This research is supported by the National Aeronautics and Space Administration.

Two-dimensional ferroelectric topological insulators in functionalized atomically thin bismuth layers

NASA Astrophysics Data System (ADS)

Kou, Liangzhi; Fu, Huixia; Ma, Yandong; Yan, Binghai; Liao, Ting; Du, Aijun; Chen, Changfeng

2018-02-01

We introduce a class of two-dimensional (2D) materials that possess coexisting ferroelectric and topologically insulating orders. Such ferroelectric topological insulators (FETIs) occur in noncentrosymmetric atomic layer structures with strong spin-orbit coupling (SOC). We showcase a prototype 2D FETI in an atomically thin bismuth layer functionalized by C H2OH , which exhibits a large ferroelectric polarization that is switchable by a ligand molecule rotation mechanism and a strong SOC that drives a band inversion leading to the topologically insulating state. An external electric field that switches the ferroelectric polarization also tunes the spin texture in the underlying atomic lattice. Moreover, the functionalized bismuth layer exhibits an additional quantum order driven by the valley splitting at the K and K' points in the Brillouin zone stemming from the symmetry breaking and strong SOC in the system, resulting in a remarkable state of matter with the simultaneous presence of the quantum spin Hall and quantum valley Hall effect. These phenomena are predicted to exist in other similarly constructed 2D FETIs, thereby offering a unique quantum material platform for discovering novel physics and exploring innovative applications.

Atomization off thin water films generated by high-frequency substrate wave vibrations.

PubMed

Collins, David J; Manor, Ofer; Winkler, Andreas; Schmidt, Hagen; Friend, James R; Yeo, Leslie Y

2012-11-01

Generating aerosol droplets via the atomization of thin aqueous films with high frequency surface acoustic waves (SAWs) offers several advantages over existing nebulization methods, particularly for pulmonary drug delivery, offering droplet sizes in the 1-5-μm range ideal for effective pulmonary therapy. Nevertheless, the physics underlying SAW atomization is not well understood, especially in the context of thin liquid film formation and spreading and how this affects the aerosol production. Here, we demonstrate that the film geometry, governed primarily by the applied power and frequency of the SAW, indeed plays a crucial role in the atomization process and, in particular, the size of the atomized droplets. In contrast to the continuous spreading of low surface energy liquids atop similar platforms, high surface energy liquids such as water, in the present case, are found to undergo transient spreading due to the SAW to form a quasisteady film whose height is determined by self-selection of the energy minimum state associated with the acoustic resonance in the film and whose length arises from a competition between acoustic streaming and capillary effects. This is elucidated from a fundamental model for the thin film spreading behavior under SAW excitation, from which we show good agreement between the experimentally measured and theoretically predicted droplet dimension, both of which consistently indicate a linear relationship between the droplet diameter and the mechanical power coupled into the liquid by the SAW (the latter captured by an acoustic Weber number to the two thirds power, and the reciprocal of the SAW frequency).

Stimulated transitions in resonant atom Majorana mixing

NASA Astrophysics Data System (ADS)

Bernabéu, José; Segarra, Alejandro

2018-02-01

Massive neutrinos demand to ask whether they are Dirac or Majorana particles. Majorana neutrinos are an irrefutable proof of physics beyond the Standard Model. Neutrinoless double electron capture is not a process but a virtual Δ L = 2 mixing between a parent A Z atom and a daughter A ( Z - 2) excited atom with two electron holes. As a mixing between two neutral atoms and the observable signal in terms of emitted two-hole X-rays, the strategy, experimental signature and background are different from neutrinoless double beta decay. The mixing is resonantly enhanced for almost degeneracy and, under these conditions, there is no irreducible background from the standard two-neutrino channel. We reconstruct the natural time history of a nominally stable parent atom since its production either by nature or in the laboratory. After the time periods of atom oscillations and the decay of the short-lived daughter atom, at observable times the relevant "stationary" states are the mixed metastable long-lived state and the non-orthogonal short-lived excited state, as well as the ground state of the daughter atom. We find that they have a natural population inversion which is most appropriate for exploiting the bosonic nature of the observed atomic transitions radiation. Among different observables of the atom Majorana mixing, we include the enhanced rate of stimulated X-ray emission from the long-lived metastable state by a high-intensity X-ray beam: a gain factor of 100 can be envisaged at current XFEL facilities. On the other hand, the historical population of the daughter atom ground state can be probed by exciting it with a current pulsed optical laser, showing the characteristic absorption lines: the whole population can be excited in a shorter time than typical pulse duration.

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.

Simulation of Quantum Phenomena in Nanowire Sensors

DTIC Science & Technology

2014-12-17

Ag and Pt atoms: search for nanocatalysts, Journal of Physics B: Atomic, Molecular and Optical Physics, (07 2011): 0. doi: 10.1088/0953- 4075/44...International Advisory Committee, African Laser Centre Annual Workshop 3-5 Nov. 2014, Moroccan Foundation for Advanced Science, Innovation & Research...atoms encapsulated inside C180 and C240 we found: 1) The Xe-C180 and Xe-C240 binding energies along some high symmetry directions showed the

Origins of phase contrast in the atomic force microscope in liquids

PubMed Central

Melcher, John; Carrasco, Carolina; Xu, Xin; Carrascosa, José L.; Gómez-Herrero, Julio; José de Pablo, Pedro; Raman, Arvind

2009-01-01

We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of higher eigenmodes. Contrary to the common assumption, phase-contrast images in liquids using soft microcantilevers are often maps of short-range conservative interactions, such as local elastic response, rather than tip-sample dissipation. The theory is used to demonstrate variations in local elasticity of purple membrane and bacteriophage ϕ29 virions in buffer solutions using the phase-contrast images. PMID:19666560

Origins of phase contrast in the atomic force microscope in liquids.

PubMed

Melcher, John; Carrasco, Carolina; Xu, Xin; Carrascosa, José L; Gómez-Herrero, Julio; José de Pablo, Pedro; Raman, Arvind

2009-08-18

We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) in liquids where low-stiffness microcantilever probes are often used for nanoscale imaging of soft biological samples with gentle forces. Under these conditions, we show that the phase contrast derives primarily from a unique energy flow channel that opens up in liquids due to the momentary excitation of higher eigenmodes. Contrary to the common assumption, phase-contrast images in liquids using soft microcantilevers are often maps of short-range conservative interactions, such as local elastic response, rather than tip-sample dissipation. The theory is used to demonstrate variations in local elasticity of purple membrane and bacteriophage 29 virions in buffer solutions using the phase-contrast images.

Researcher Supported by Atomic Energy Commission and U.S. Department of

Science.gov Websites

Energy is Co-Winner Of 2008 Nobel Prize in Physics October 7, 2008 Researcher Supported by Atomic Energy Commission and U.S. Department of Energy is Co-Winner Of 2008 Nobel Prize in Physics -winning the 2008 Nobel Prize in Physics for their theoretical insights that provide a deeper understanding

First-Order Quantum Phase Transition for Dicke Model Induced by Atom-Atom Interaction

NASA Astrophysics Data System (ADS)

Zhao, Xiu-Qin; Liu, Ni; Liang, Jiu-Qing

2017-05-01

In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model’s ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength. Supported by the National Natural Science Foundation of China under Grant Nos. 11275118, 11404198, 91430109, 61505100, 51502189, and the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province (STIP) under Grant No. 2014102, and the Launch of the Scientific Research of Shanxi University under Grant No. 011151801004, and the National Fundamental Fund of Personnel Training under Grant No. J1103210. The Natural Science Foundation of Shanxi Province under Grant No. 2015011008

Nuclear Physics Made Very, Very Easy

NASA Technical Reports Server (NTRS)

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

1968-01-01

The fundamental approach to nuclear physics was prepared to introduce basic reactor principles to various groups of non-nuclear technical personnel associated with NERVA Test Operations. NERVA Test Operations functions as the field test group for the Nuclear Rocket Engine Program. Nuclear Engine for Rocket Vehicle Application (NERVA) program is the combined efforts of Aerojet-General Corporation as prime contractor, and Westinghouse Astronuclear Laboratory as the major subcontractor, for the assembly and testing of nuclear rocket engines. Development of the NERVA Program is under the direction of the Space Nuclear Propulsion Office, a joint agency of the U.S. Atomic Energy Commission and the National Aeronautics and Space Administration.

Research as a guide for curriculum development: An example from introductory spectroscopy. II. Addressing student difficulties with atomic emission spectra

NASA Astrophysics Data System (ADS)

Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.

2015-02-01

This is the second of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. Paper I describes how several conceptual and reasoning difficulties were identified among university students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. This second article (Paper II) illustrates how findings from this research informed the development of a tutorial that led to improvement in student understanding of atomic emission spectra.

Research as a guide for curriculum development: An example from introductory spectroscopy. I. Identifying student difficulties with atomic emission spectra

NASA Astrophysics Data System (ADS)

Ivanjek, L.; Shaffer, P. S.; McDermott, L. C.; Planinic, M.; Veza, D.

2015-01-01

This is the first of two closely related articles (Paper I and Paper II) that together illustrate how research in physics education has helped guide the design of instruction that has proved effective in improving student understanding of atomic spectroscopy. Most of the more than 1000 students who participated in this four-year investigation were science majors enrolled in the introductory calculus-based physics course at the University of Washington (UW) in Seattle, WA, USA. The others included graduate and undergraduate teaching assistants at UW and physics majors in introductory and advanced physics courses at the University of Zagreb, Zagreb, Croatia. About half of the latter group were preservice high school physics teachers. This article (Paper I) describes how several serious conceptual and reasoning difficulties were identified among students as they tried to relate a discrete line spectrum to the energy levels of atoms in a light source. Paper II illustrates how findings from this research informed the development of a tutorial that led to significant improvement in student understanding of atomic emission spectra.

Celebrating 50 years of the laser (Scientific session of the general meeting of the Physical Sciences Division of the Russian Academy of Sciences, 13 December 2010)

NASA Astrophysics Data System (ADS)

2011-08-01

A scientific session of the general meeting of the Physical Sciences Division of the Russian Academy of Sciences (RAS) dedicated to the 50th anniversary of the creation of lasers was held in the Conference Hall of the Lebedev Physical Institute, RAS, on 13 December 2010. The agenda of the session announced on the website www.gpad.ac.ru of the RAS Physical Sciences Division listed the following reports: (1) Matveev V A, Bagaev S N Opening speech; (2) Bratman V L, Litvak A G, Suvorov E V (Institute of Applied Physics, RAS, Nizhny Novgorod) "Mastering the terahertz domain: sources and applications"; (3) Balykin V I (Institute of Spectroscopy, RAS, Troitsk, Moscow region) "Ultracold atoms and atom optics"; (4) Ledentsov N N (Ioffe Physical Technical Institute, RAS, St. Petersburg) "New-generation surface-emitting lasers as the key element of the computer communication era"; (5) Krasil'nik Z F (Institute for the Physics of Microstructures, RAS, Nizhny Novgorod) "Lasers for silicon optoelectronics"; (6) Shalagin A M (Institute of Automation and Electrometry, Siberian Branch, RAS, Novosibirsk) "High-power diode-pumped alkali metal vapor lasers"; (7) Kul'chin Yu N (Institute for Automation and Control Processes, Far Eastern Branch, RAS, Vladivostok) "Photonics of self-organizing biomineral nanostructures"; (8) Kolachevsky N N (Lebedev Physical Institute, RAS, Moscow) "Laser cooling of rare-earth atoms and precision measurements". The papers written on the basis of reports 2-4, 7, and 8 are published below.Because the paper based on report 6 was received by the Editors late, it will be published in the October issue of Physics-Uspekhi together with the material related to the Scientific Session of the Physical Sciences Division, RAS, of 22 December 2010. • Mastering the terahertz domain: sources and applications, V L Bratman, A G Litvak, E V Suvorov Physics-Uspekhi, 2011, Volume 54, Number 8, Pages 837-844 • Ultracold atoms and atomic optics, V I Balykin Physics-Uspekhi, 2011, Volume 54, Number 8, Pages 844-852 • New-generation vertically emitting lasers as a key factor in the computer communication era, N N Ledentsov, J A Lott Physics-Uspekhi, 2011, Volume 54, Number 8, Pages 853-858 • The photonics of self-organizing biomineral nanostructures, Yu N Kulchin Physics-Uspekhi, 2011, Volume 54, Number 8, Pages 858-863 • Laser cooling of rare-earth atoms and precision measurements, N N Kolachevsky Physics-Uspekhi, 2011, Volume 54, Number 8, Pages 863-870

Theory of atomic spectral emission intensity

NASA Astrophysics Data System (ADS)

Yngström, Sten

1994-07-01

The theoretical derivation of a new spectral line intensity formula for atomic radiative emission is presented. The theory is based on first principles of quantum physics, electrodynamics, and statistical physics. Quantum rules lead to revision of the conventional principle of local thermal equilibrium of matter and radiation. Study of electrodynamics suggests absence of spectral emission from fractions of the numbers of atoms and ions in a plasma due to radiative inhibition caused by electromagnetic force fields. Statistical probability methods are extended by the statement: A macroscopic physical system develops in the most probable of all conceivable ways consistent with the constraining conditions for the system. The crucial role of statistical physics in transforming quantum logic into common sense logic is stressed. The theory is strongly supported by experimental evidence.

Imaging Multi-Particle Atomic and Molecular Dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landers, Allen

2016-02-12

Final Report for Grant Number: DE- FG02-10ER16146 This grant supported research in basic atomic, molecular and optical physics related to the interactions of atoms and molecules with photons and electrons. The duration of the grant was the 5 year period from 4/1/2010 – 10/31/2015. All of the support from the grant was used to pay salaries of the PI, graduate students, and undergraduates and travel to conferences and meetings. The results were in the form of publications in peer reviewed journals. There were 20 peer reviewed publications over these 5 years with 2 of the publications in Physical Review Lettersmore » and 1 in Nature; all of the other articles were in respected peer reviewed journals (Physical Review A, New Journal of Physics, Journal of Physics B ...).« less

Two-Dimensional Arrays of Neutral Atom Quantum Gates

DTIC Science & Technology

2012-10-20

Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS quantum computing , Rydberg atoms, entanglement Mark Saffman University of...Nature Physics, (01 2009): 0. doi: 10.1038/nphys1178 10/19/2012 9.00 K. Mølmer, M. Saffman. Scaling the neutral-atom Rydberg gate quantum computer by...Saffman, E. Brion, K. Mølmer. Error Correction in Ensemble Registers for Quantum Repeaters and Quantum Computers , Physical Review Letters, (3 2008): 0

Applications of Atomic Systems in Quantum Simulation, Quantum Computation and Topological Phases of Matter

NASA Astrophysics Data System (ADS)

Wang, Shengtao

The ability to precisely and coherently control atomic systems has improved dramatically in the last two decades, driving remarkable advancements in quantum computation and simulation. In recent years, atomic and atom-like systems have also been served as a platform to study topological phases of matter and non-equilibrium many-body physics. Integrated with rapid theoretical progress, the employment of these systems is expanding the realm of our understanding on a range of physical phenomena. In this dissertation, I draw on state-of-the-art experimental technology to develop several new ideas for controlling and applying atomic systems. In the first part of this dissertation, we propose several novel schemes to realize, detect, and probe topological phases in atomic and atom-like systems. We first theoretically study the intriguing properties of Hopf insulators, a peculiar type of topological insulators beyond the standard classification paradigm of topological phases. Using a solid-state quantum simulator, we report the first experimental observation of Hopf insulators. We demonstrate the Hopf fibration with fascinating topological links in the experiment, showing clear signals of topological phase transitions for the underlying Hamiltonian. Next, we propose a feasible experimental scheme to realize the chiral topological insulator in three dimensions. They are a type of topological insulators protected by the chiral symmetry and have thus far remained unobserved in experiment. We then introduce a method to directly measure topological invariants in cold-atom experiments. This detection scheme is general and applicable to probe of different topological insulators in any spatial dimension. In another study, we theoretically discover a new type of topological gapless rings, dubbed a Weyl exceptional ring, in three-dimensional dissipative cold atomic systems. In the second part of this dissertation, we focus on the application of atomic systems in quantum computation and simulation. Trapped atomic ions are one of the leading platforms to build a scalable, universal quantum computer. The common one-dimensional setup, however, greatly limits the system's scalability. By solving the critical problem of micromotion, we propose a two-dimensional architecture for scalable trapped-ion quantum computation. Hamiltonian tomography for many-body quantum systems is essential for benchmarking quantum computation and simulation. By employing dynamical decoupling, we propose a scalable scheme for full Hamiltonian tomography. The required number of measurements increases only polynomially with the system size, in contrast to an exponential scaling in common methods. Finally, we work toward the goal of demonstrating quantum supremacy. A number of sampling tasks, such as the boson sampling problem, have been proposed to be classically intractable under mild assumptions. An intermediate quantum computer can efficiently solve the sampling problem, but the correct operation of the device is not known to be classically verifiable. Toward practical verification, we present an experimental friendly scheme to extract useful and robust information from the quantum boson samplers based on coarse-grained measurements. In a separate study, we introduce a new model built from translation-invariant Ising-interacting spins. This model possesses several advantageous properties, catalyzing the ultimate experimental demonstration of quantum supremacy.

PREFACE: XXV International Conference on Photonic, Electronic and Atomic Collisions

NASA Astrophysics Data System (ADS)

Becker, Uwe; Moshammer, Robert; Mokler, Paul; Ullrich, Joachim

2007-07-01

The XXVth ICPEAC in Freiburg marked a notable anniversary in collision physics: half a century ago the first conference in the series of International Conferences on the Physics of Electronic and Atomic Collisions (ICPEAC) was held in New York (1958). Since then, the development of electronic and atomic collision physics has seen tremendous progress. Starting during a time, when this field was regarded as somehow out-of-date, certainly not being in the main stream compared to particle and high-energy physics, it has expanded in a rather exceptional and unforeseen way. Over the years the original scope on electronic, atomic and heavy-ion collision physics was extended substantially to include upcoming expanding fields like synchrotron-radiation and strong-field laser-based atomic and molecular physics giving rise to a change of name to 'Photonic', Electronic and Atomic Collisions (ICPEAC) being used for the first time for the ICPEAC in Santa Fee in 2001. Nowadays, the ICPEAC has opened its agenda even more widely to other fields of atomic and molecular physics, such as interactions with clusters, bio-molecules and surfaces, to cold collisions, coherent control, femto- and attosecond physics and, with the Freiburg conference, to the application of free-electron lasers in the vacuum ultraviolet and soft x-ray regime, a field of potentially huge future impact in essentially all areas of science. In this larger context the XXVth ICPEAC in Freiburg with more than 800 participants set new standards. Representatives from all fields of Atomic, Molecular and Photon-based science came together and had very fruitful, inter-disciplinary discussions. This new forum of collision-based AMP physics will serve as a showcase example of future conferences, bridging not only the gap between different fields of collision physics but also, equally important, between different continents and cultures. The next ICPEAC is going to take place in Kalamazoo in North America, the one after that in Belfast back in Europe, and the subsequent one, 2013 in Lanzhou, will be the first one ever held in China. A great perspective for this ever-growing field of science! Uwe Becker (Fritz-Haber-Institut, Berlin) Robert Moshammer (Max-Planck-Institut für Kernphysik, Heidelberg) Paul Mokler (Gesellschaft für Schwerionenforschung, Darmstadt) Joachim Ullrich (Max-Planck-Institut für Kernphysik, Heidelberg) Editors Relaxed atmosphere for discussions during coffee breaks at ICPEAC XXV in Freiburg. The PDF file contains details of previous conferences, sponsors, exhibitors and committees.

Application of pulsed multi-ion irradiations in radiation damage research: A stochastic cluster dynamics simulation study

NASA Astrophysics Data System (ADS)

Hoang, Tuan L.; Nazarov, Roman; Kang, Changwoo; Fan, Jiangyuan

2018-07-01

Under the multi-ion irradiation conditions present in accelerated material-testing facilities or fission/fusion nuclear reactors, the combined effects of atomic displacements with radiation products may induce complex synergies in the structural materials. However, limited access to multi-ion irradiation facilities and the lack of computational models capable of simulating the evolution of complex defects and their synergies make it difficult to understand the actual physical processes taking place in the materials under these extreme conditions. In this paper, we propose the application of pulsed single/dual-beam irradiation as replacements for the expensive steady triple-beam irradiation to study radiation damages in materials under multi-ion irradiation.

Ultracold-atom quantum simulator for attosecond science

NASA Astrophysics Data System (ADS)

Sala, Simon; Förster, Johann; Saenz, Alejandro

2017-01-01

A quantum simulator based on ultracold optically trapped atoms for simulating the physics of atoms and molecules in ultrashort intense laser fields is introduced. The slowing down by about 13 orders of magnitude allows one to watch in slow motion the tunneling and recollision processes that form the heart of attosecond science. The extreme flexibility of the simulator promises a deeper understanding of strong-field physics, especially for many-body systems beyond the reach of classical computers. The quantum simulator can experimentally straightforwardly be realized and is shown to recover the ionization characteristics of atoms in the different regimes of laser-matter interaction.

Chemical and physical insight on the local properties of the phosphides XSiP2 (X = Be, Mg, Cd, Zn and Hg) under pressure: from first principles calculations

NASA Astrophysics Data System (ADS)

Ouahrani, Tarik

2013-09-01

Local properties of the XSiP2 (X = Be, Mg, Cd, Zn and Hg) compounds are revisited through the partition of static thermodynamic properties under pressure. We pay attention to the metallization that occurs when the investigated compounds undergo a phase transition from chalcopyrite to the NaCl structure. Electron localization function analysis shows that the local valence basin attractors values decrease as a function of pressure. As the pressure increases, the tetragonal distortion ( c/ a) diminishes while the degree of ionicity enhances. In addition, by means of atom in molecule approach, atomic-like local compressibility and pressures are analyzed. We found that the basins volumes of the investigated compounds in the NaCl phase have lower compressibilities than those in the chalcopyrite phase. According to the predicted core-valence basins, the phosphorus cation is found to be the more affected by the hydrostatic pressure.

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…

Physics and Its Multiple Roles in the International Atomic Energy Agency

NASA Astrophysics Data System (ADS)

Massey, Charles D.

2017-01-01

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

NUCLEAR CHEMISTRY ANNUAL REPORT 1970

DOE Office of Scientific and Technical Information (OSTI.GOV)

Authors, Various

Papers are presented for the following topics: (1) Nuclear Structure and Nuclear Properties - (a) Nuclear Spectroscopy and Radioactivity; (b) Nuclear Reactions and Scattering; (c) Nuclear Theory; and (d) Fission. (2) Chemical and Atomic Physics - (a) Atomic and Molecular Spectroscopy; and (b) Hyperfine Interactions. (3) Physical, Inorganic, and Analytical Chemistry - (a) X-Ray Crystallography; (b) Physical and Inorganic Chemistry; (c) Radiation Chemistry; and (d) Chemical Engineering. (4) Instrumentation and Systems Development.

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-dimensional ultracold gas experiment, T V Barmashova, K A Mart'yanov, V B Makhalov, A V Turlapov Physics-Uspekhi, 2016, Volume 59, Number 2, Pages 174-183 • Ultraprecise optical frequency standards based on ultracold atoms: state of the art and prospects, A V Taichenachev, V I Yudin, S N Bagayev Physics-Uspekhi, 2016, Volume 59, Number 2, Pages 184-195 • Spectroscopy of cold rubidium Rydberg atoms for applications in quantum information, I I Ryabtsev, I I Beterov, D B Tret'yakov, V M Èntin, E A Yakshina Physics-Uspekhi, 2016, Volume 59, Number 2, Pages 196-208

The next large helical devices

NASA Astrophysics Data System (ADS)

Iiyoshi, Atsuo; Yamazaki, Kozo

1995-06-01

Helical systems have the strong advantage of inherent steady-state operation for fusion reactors. Two large helical devices with fully superconducting coil systems are presently under design and construction. One is the LHD (Large Helical Device) [Fusion Technol. 17, 169 (1990)] with major radius=3.9 m and magnetic field=3-4 T, that is under construction during 1990-1997 at NIFS (National Institute for Fusion Science), Nagoya/Toki, Japan; it features continuous helical coils and a clean helical divertor focusing on edge configuration optimization. The other one in the W7-X (Wendelstein 7-X) [in Plasma Physics and Controlled Fusion Nuclear Research, 1990, (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525] with major radius=5.5 m and magnetic field=3 T, that is under review at IPP (Max-Planck Institute for Plasma Physics), Garching, Germany; it has adopted a modular coil system after elaborate optimization studies. These two programs are complementary in promoting world helical fusion research and in extending the understanding of toroidal plasmas through comparisons with large tokamaks.

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.

Light element opacities of astrophysical interest from ATOMIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colgan, J.; Kilcrease, D. P.; Magee, N. H. Jr.

We present new calculations of local-thermodynamic-equilibrium (LTE) light element opacities from the Los Alamos ATOMIC code for systems of astrophysical interest. ATOMIC is a multi-purpose code that can generate LTE or non-LTE quantities of interest at various levels of approximation. Our calculations, which include fine-structure detail, represent a systematic improvement over previous Los Alamos opacity calculations using the LEDCOP legacy code. The ATOMIC code uses ab-initio 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. ATOMIC also incorporates a newmore » 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. Our new calculations are made for elements of astrophysical interest and for a wide range of temperatures and densities.« less

Benchmarking transition energies and emission strengths for X-ray astrophysics with measurements at the Livermore EBITs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hell, Natalie

K-shell transitions in astrophysically abundant metals and L-shell transitions in Fe group elements show characteristic signatures in the soft X-ray spectrum in the energy range 0.1–10 keV. These signatures have great diagnostic value for plasma parameters such as electron and ion temperatures and densities, and can thus help understand the physics controlling the energetic processes in astrophysical sources. This diagnostic power increases with advances in spectral resolution and effective area of the employed X-ray observatories. However, to make optimal use of the diagnostic potential – whether through global spectral modeling or through diagnostics from local modeling of individual lines –more » the underlying atomic physics has to be complete and well known. With the next generation of soft X-ray observatories featuring micro-calorimeters such as the SXS on Astro- H/Hitomi and the X-IFU on Athena, broadband high-resolution spectroscopy with large effective area will become more commonly available in the next decade. With these spectrometers, the accuracy of the plasma parameters derived from spectral modeling will be limited by the uncertainty of the reference atomic data rather than by instrumental factors, as is sometimes already the case for the high-resolution grating observations with Chandra-HETG and XMM-Newton-RGS. To take full advantage of the measured spectra, assessment of the accuracy of and improvements to the available atomic reference data are therefore important. Dedicated measurements in the laboratory are essential to benchmark the theoretical calculations providing the bulk of the reference data used in astrophysics. Experiments at the Lawrence Livermore National Laboratory electron beam ion traps (EBIT-I and SuperEBIT) have a long history of providing this service. In this work, I present new measurements of transition energies and absolute electron impact excitation cross sections geared towards currently open atomic physics data needs.« less

The Chip-Scale Atomic Clock - Low-Power Physics Package

DTIC Science & Technology

2004-12-01

36th Annual Precise Time and Time Interval (PTTI) Meeting 339 THE CHIP-SCALE ATOMIC CLOCK – LOW-POWER PHYSICS PACKAGE R. Lutwak ...pdf/documents/ds-x72.pdf [2] R. Lutwak , D. Emmons, W. Riley, and R. M. Garvey, 2003, “The Chip-Scale Atomic Clock – Coherent Population Trapping vs...2002, Reston, Virginia, USA (U.S. Naval Observatory, Washington, D.C.), pp. 539-550. [3] R. Lutwak , D. Emmons, T. English, and W. Riley, 2004

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum. [atomic spectra and electronic structure of alkali metals

NASA Technical Reports Server (NTRS)

Hartmann, S. R.; Happer, W.

1974-01-01

The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity.

Probing the porosity of cocrystallized MCM-49/ZSM-35 zeolites by hyperpolarized 129Xe NMR.

PubMed

Liu, Yong; Zhang, Weiping; Xie, Sujuan; Xu, Longya; Han, Xiuwen; Bao, Xinhe

2008-01-31

One- and two-dimensional 129Xe NMR spectroscopy has been employed to study the porosity of cocrystallized MCM-49/ZSM-35 zeolites under the continuous flow of hyperpolarized xenon gas. It is found by variable-temperature experiments that Xe atoms can be adsorbed in different domains of MCM-49/ZSM-35 cocrystallized zeolites and the mechanically mixed counterparts. The exchange of Xe atoms in different types of pores is very fast at ambient temperatures. Even at very low temperature two-dimensional exchange spectra (EXSY) show that Xe atoms still undergo much faster exchange between MCM-49 and ZSM-35 analogues in the cocrystallized zeolites than in the mechanical mixture. This demonstrates that the MCM-49 and ZSM-35 analogues in cocrystallized zeolites may be stacked much closer than in the physical mixture, and some parts of intergrowth may be formed due to the partially similar basic structure of MCM-49 and ZSM-35.

The importance of multi-level Rydberg interaction in electric field tuned Förster resonances

NASA Astrophysics Data System (ADS)

Kondo, Jorge; Booth, Donald; Gonçalves, Luis; Shaffer, James; Marcassa, Luis

2016-05-01

Many-body physics has been investigated in ultracold Rydberg atom systems, mainly because important parameters, such as density and interaction strength, can be controlled. Several puzzling experimental observations on Förster resonances have been associated to many-body effects, usually by comparison to complex theoretical models. In this work, we investigate the dc electric field dependence of 2 Förster resonant processes in ultracold 85 Rb, 37D5 / 2 + 37D5 / 2 --> 35 L(L = O , Q) + 39P3 / 2 , as a function of the atomic density in an optical dipole trap. At low densities, the 39 P yield as a function of electric field exhibits resonances. With increasing density, the linewidths increase until the peaks merge. Even under these extreme conditions, where many-body effects were expected to play a role, the 39 P population depends quadratically on the total Rydberg atom population. In order to explain our results, we implement a theoretical model which takes into account the multi-level character of the interactions and Rydberg atom blockade process using only atom pair interactions. The comparison between the experimental data and the model is very good, suggesting that the Förster resonant processes are dominated by 2-body interactions. This work is supported by FAPESP, AFOSR, NSF, INCT-IQ and CNPq.

A New Type of Atom Interferometry for Testing Fundamental Physics

NASA Astrophysics Data System (ADS)

Lorek, Dennis; Lämmerzahl, Claus; Wicht, Andreas

We present a new type of atom interferometer (AI) that provides a tool for ultra-high precision tests of fundamental physics. As an example we present how an AI based on highly charged hydrogen-like atoms is affected by gravitational waves (GW). A qualitative description of the quantum interferometric measurement principle is given, the modifications in the atomic Hamiltonian caused by the GW are presented, and the size of the resulting frequency shifts in hydrogen-like atoms is estimated. For a GW amplitude of h = 10-23 the frequency shift is of the order of 110μHz for an AI based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current AIs in 1s.

Coherent Radiation in Atomic Systems

NASA Astrophysics Data System (ADS)

Sutherland, Robert Tyler

Over the last century, quantum mechanics has dramatically altered our understanding of light and matter. Impressively, exploring the relationship between the two continues to provide important insights into the physics of many-body systems. In this thesis, we add to this still growing field of study. Specifically, we discuss superradiant line-broadening and cooperative dipole-dipole interactions for cold atom clouds in the linear-optics regime. We then discuss how coherent radiation changes both the photon scattering properties and the excitation distribution of atomic arrays. After that, we explore the nature of superradiance in initially inverted clouds of multi-level atoms. Finally, we explore the physics of clouds with degenerate Zeeman ground states, and show that this creates quantum effects that fundamentally change the photon scattering of atomic ensembles.

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)

Time-resolved microplasma excitation temperature in a pulsed microwave discharge

NASA Astrophysics Data System (ADS)

Hopwood, Jeffrey; Monfared, Shabnam; Hoskinson, Alan

2013-09-01

Microwave-driven microplasmas are usually operated in a steady-state mode such that the electron temperature is constant in time. Transient measurements of excitation temperature and helium emission lines, however, suggest that short microwave pulses can be used to raise the electron energy by 20-30% for approximately 100 ns. Time-resolved optical emission spectrometry reveals an initial burst of light emission from the igniting microplasma. This emission overshoot is also correlated with a measured increase in excitation temperature. Excimer emission lags atomic emission, however, and does not overshoot. A simple model demonstrates that an increase in electron temperature is responsible for the overshoot of atomic optical emission at the beginning of each microwave pulse. The formation of dimers and subsequent excimer emission requires slower three-body collisions with the excited rare gas atom; this is why excimer emission does not overshoot the steady state value. Similar experimental and modeling results are observed in argon gas. The overshoot in electron temperature may be used to manipulate the collisional production of species in microplasmas using short, low-duty cycle microwave pulses. This material is based upon work supported by the USAF and Physical Sciences Inc., under contract No. FA8650-C-12-C-2312. Additional support was provided by the DARPA MPD program under award FA9550-12-1-0006.

18 CFR 35.29 - Treatment of special assessments levied under the Atomic Energy Act of 1954, as amended by Title...

Code of Federal Regulations, 2011 CFR

2011-04-01

... assessments levied under the Atomic Energy Act of 1954, as amended by Title XI of the Energy Policy Act of... Other Filing Requirements § 35.29 Treatment of special assessments levied under the Atomic Energy Act of... relating to special assessments under the Atomic Energy Act of 1954, as amended by the Energy Policy Act of...

18 CFR 35.29 - Treatment of special assessments levied under the Atomic Energy Act of 1954, as amended by Title...

Code of Federal Regulations, 2012 CFR

2012-04-01

... assessments levied under the Atomic Energy Act of 1954, as amended by Title XI of the Energy Policy Act of... Other Filing Requirements § 35.29 Treatment of special assessments levied under the Atomic Energy Act of... relating to special assessments under the Atomic Energy Act of 1954, as amended by the Energy Policy Act of...

18 CFR 35.29 - Treatment of special assessments levied under the Atomic Energy Act of 1954, as amended by Title...

Code of Federal Regulations, 2010 CFR

2010-04-01

... assessments levied under the Atomic Energy Act of 1954, as amended by Title XI of the Energy Policy Act of... Other Filing Requirements § 35.29 Treatment of special assessments levied under the Atomic Energy Act of... relating to special assessments under the Atomic Energy Act of 1954, as amended by the Energy Policy Act of...

18 CFR 35.29 - Treatment of special assessments levied under the Atomic Energy Act of 1954, as amended by Title...

Code of Federal Regulations, 2013 CFR

2013-04-01

... assessments levied under the Atomic Energy Act of 1954, as amended by Title XI of the Energy Policy Act of... Other Filing Requirements § 35.29 Treatment of special assessments levied under the Atomic Energy Act of... relating to special assessments under the Atomic Energy Act of 1954, as amended by the Energy Policy Act of...

18 CFR 35.29 - Treatment of special assessments levied under the Atomic Energy Act of 1954, as amended by Title...

Code of Federal Regulations, 2014 CFR

2014-04-01

... assessments levied under the Atomic Energy Act of 1954, as amended by Title XI of the Energy Policy Act of... Other Filing Requirements § 35.29 Treatment of special assessments levied under the Atomic Energy Act of... relating to special assessments under the Atomic Energy Act of 1954, as amended by the Energy Policy Act of...

Measurement of the electron shake-off in the β-decay of laser-trapped 6He atoms

NASA Astrophysics Data System (ADS)

Hong, Ran; Bagdasarova, Yelena; Garcia, Alejandro; Storm, Derek; Sternberg, Matthew; Swanson, Erik; Wauters, Frederik; Zumwalt, David; Bailey, Kevin; Leredde, Arnaud; Mueller, Peter; O'Connor, Thomas; Flechard, Xavier; Liennard, Etienne; Knecht, Andreas; Naviliat-Cuncic, Oscar

2016-03-01

Electron shake-off is an important process in many high precision nuclear β-decay measurements searching for physics beyond the standard model. 6He being one of the lightest β-decaying isotopes, has a simple atomic structure. Thus, it is well suited for testing calculations of shake-off effects. Shake-off probabilities from the 23S1 and 23P2 initial states of laser trapped 6He matter for the on-going beta-neutrino correlation study at the University of Washington. These probabilities are obtained by analyzing the time-of-flight distribution of the recoil ions detected in coincidence with the beta particles. A β-neutrino correlation independent analysis approach was developed. The measured upper limit of the double shake-off probability is 2 ×10-4 at 90% confidence level. This result is ~100 times lower than the most recent calculation by Schulhoff and Drake. This work is supported by DOE, Office of Nuclear Physics, under Contract Nos. DE-AC02-06CH11357 and DE-FG02-97ER41020.

Failure of local thermal equilibrium in quantum friction

DOE PAGES

Intravaia, Francesco; Behunin, Ryan; Henkel, Carsten; ...

2016-09-01

Recent progress in manipulating atomic and condensed matter systems has instigated a surge of interest in nonequilibrium physics, including many-body dynamics of trapped ultracold atoms and ions, near-field radiative heat transfer, and quantum friction. Under most circumstances the complexity of such nonequilibrium systems requires a number of approximations to make theoretical descriptions tractable. In particular, it is often assumed that spatially separated components of a system thermalize with their immediate surroundings, although the global state of the system is out of equilibrium. This powerful assumption reduces the complexity of nonequilibrium systems to the local application of well-founded equilibrium concepts. Whilemore » this technique appears to be consistent for the description of some phenomena, we show that it fails for quantum friction by underestimating by approximately 80% the magnitude of the drag force. Here, our results show that the correlations among the components of driven, but steady-state, quantum systems invalidate the assumption of local thermal equilibrium, calling for a critical reexamination of this approach for describing the physics of nonequilibrium systems.« less

The physics of interstellar shock waves

NASA Technical Reports Server (NTRS)

Shull, J. Michael; Draine, Bruce T.

1987-01-01

This review discusses the observations and theoretical models of interstellar shock waves, in both diffuse cloud and molecular cloud environments. It summarizes the relevant gas dynamics, atomic, molecular and grain processes, radiative transfer, and physics of radiative and magnetic precursors in shock models. It then describes the importance of shocks for observations, diagnostics, and global interstellar dynamics. It concludes with current research problems and data needs for atomic, molecular and grain physics.

The Fair Facility

NASA Astrophysics Data System (ADS)

Nilsson, Thomas

2015-03-01

The FAIR (Facility for Antiproton and Ion Beams), under construction at the GSI site in Darmstadt, Germany, will be addressing a wealth of outstanding questions within the realm of subatomic, atomic and plasma physics through a combination of novel accelerators, storage rings and innovative experimental setups. The envisaged programme of FAIR yields a breadth that is unprecedented at an accelerator-based infrastructure. A brief review of the FAIR infrastructure and scientific reach is made, together with an update of the status of the construction.

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…

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Systematic measurements of opacity dependence on temperature, density, and atomic number at stellar interior conditions

NASA Astrophysics Data System (ADS)

Nagayama, Taisuke

2017-10-01

Model predictions for iron opacity are notably different from measurements performed at matter conditions similar to the boundary between the solar radiation and convection zones. The calculated iron opacities have narrower spectral lines, weaker quasi-continuum at short wavelength, and deeper opacity windows than the measurements. If correct, these measurements help resolve a decade old problem in solar physics. A key question is therefore: What is responsible for the model-data discrepancy? The answer is complex because the experiments are challenging and opacity theories depend on multiple entangled physical processes such as the influence of completeness and accuracy of atomic states, line broadening, contributions from myriad transitions from excited states, and multi-photon absorption processes. To help determine the cause of this discrepancy, a systematic study of opacity variation with temperature, density, and atomic number is underway. Measurements of chromium, iron, and nickel opacities have been performed at two different temperatures and densities. The collection of measured opacities provides constraints on hypotheses to explain the discrepancy. We will discuss implications of measured opacities, experimental errors, and possible opacity model refinements. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.

Experimental methods of molecular matter-wave optics.

PubMed

Juffmann, Thomas; Ulbricht, Hendrik; Arndt, Markus

2013-08-01

We describe the state of the art in preparing, manipulating and detecting coherent molecular matter. We focus on experimental methods for handling the quantum motion of compound systems from diatomic molecules to clusters or biomolecules.Molecular quantum optics offers many challenges and innovative prospects: already the combination of two atoms into one molecule takes several well-established methods from atomic physics, such as for instance laser cooling, to their limits. The enormous internal complexity that arises when hundreds or thousands of atoms are bound in a single organic molecule, cluster or nanocrystal provides a richness that can only be tackled by combining methods from atomic physics, chemistry, cluster physics, nanotechnology and the life sciences.We review various molecular beam sources and their suitability for matter-wave experiments. We discuss numerous molecular detection schemes and give an overview over diffraction and interference experiments that have already been performed with molecules or clusters.Applications of de Broglie studies with composite systems range from fundamental tests of physics up to quantum-enhanced metrology in physical chemistry, biophysics and the surface sciences.Nanoparticle quantum optics is a growing field, which will intrigue researchers still for many years to come. This review can, therefore, only be a snapshot of a very dynamical process.

Quantum chaos in ultracold collisions of gas-phase erbium atoms.

PubMed

Frisch, Albert; Mark, Michael; Aikawa, Kiyotaka; Ferlaino, Francesca; Bohn, John L; Makrides, Constantinos; Petrov, Alexander; Kotochigova, Svetlana

2014-03-27

Atomic and molecular samples reduced to temperatures below one microkelvin, yet still in the gas phase, afford unprecedented energy resolution in probing and manipulating the interactions between their constituent particles. As a result of this resolution, atoms can be made to scatter resonantly on demand, through the precise control of a magnetic field. For simple atoms, such as alkalis, scattering resonances are extremely well characterized. However, ultracold physics is now poised to enter a new regime, where much more complex species can be cooled and studied, including magnetic lanthanide atoms and even molecules. For molecules, it has been speculated that a dense set of resonances in ultracold collision cross-sections will probably exhibit essentially random fluctuations, much as the observed energy spectra of nuclear scattering do. According to the Bohigas-Giannoni-Schmit conjecture, such fluctuations would imply chaotic dynamics of the underlying classical motion driving the collision. This would necessitate new ways of looking at the fundamental interactions in ultracold atomic and molecular systems, as well as perhaps new chaos-driven states of ultracold matter. Here we describe the experimental demonstration that random spectra are indeed found at ultralow temperatures. In the experiment, an ultracold gas of erbium atoms is shown to exhibit many Fano-Feshbach resonances, of the order of three per gauss for bosons. Analysis of their statistics verifies that their distribution of nearest-neighbour spacings is what one would expect from random matrix theory. The density and statistics of these resonances are explained by fully quantum mechanical scattering calculations that locate their origin in the anisotropy of the atoms' potential energy surface. Our results therefore reveal chaotic behaviour in the native interaction between ultracold atoms.

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)

The influence of atomic alignment on absorption and emission spectroscopy

NASA Astrophysics Data System (ADS)

Zhang, Heshou; Yan, Huirong; Richter, Philipp

2018-06-01

Spectroscopic observations play essential roles in astrophysics. They are crucial for determining physical parameters in the universe, providing information about the chemistry of various astronomical environments. The proper execution of the spectroscopic analysis requires accounting for all the physical effects that are compatible to the signal-to-noise ratio. We find in this paper the influence on spectroscopy from the atomic/ground state alignment owing to anisotropic radiation and modulated by interstellar magnetic field, has significant impact on the study of interstellar gas. In different observational scenarios, we comprehensively demonstrate how atomic alignment influences the spectral analysis and provide the expressions for correcting the effect. The variations are even more pronounced for multiplets and line ratios. We show the variation of the deduced physical parameters caused by the atomic alignment effect, including alpha-to-iron ratio ([X/Fe]) and ionisation fraction. Synthetic observations are performed to illustrate the visibility of such effect with current facilities. A study of PDRs in ρ Ophiuchi cloud is presented to demonstrate how to account for atomic alignment in practice. Our work has shown that due to its potential impact, atomic alignment has to be included in an accurate spectroscopic analysis of the interstellar gas with current observational capability.

Modifications of structural, chemical, and electrical characteristics of Er2O3/Si interface under Co-60 gamma irradiation

NASA Astrophysics Data System (ADS)

Kaya, Senol; Yilmaz, Ercan

2018-03-01

This paper reports the influences of gamma radiation on the structural, electrical, and chemical characteristics of erbium oxide (Er2O3) thin films and the possible mechanisms underlying these irradiation-induced effects. The crystallographic and morphological modifications under gamma irradiation were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively, while radiation influences on electrochemical characteristics were analyzed by X-ray photoelectron spectroscopy (XPS). Furthermore, changes in electrical characteristics were analyzed on the basis of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements. The XRD results demonstrated that small atomic displacement was observed and that the grain size of the nanostructure slightly increased. Improvements in surface roughness were observed in AFM measurements. The observed variations in the XRD and AFM measurements can be attributed to the radiation-induced local heating and microscopic atomic mobility. In addition, the XPS analysis obviously demonstrated that the oxygen vacancies increased with irradiation dose because of the breaking of Er2O3 and ErxOy bonds. Significant influences of the generated oxygen vacancies on the electrical measurements were observed, and the radiation-induced hole traps, which caused large flat band shifts, can be attributed to the generated oxygen vacancies. The results show that radiation does not degrade the physical characteristics significantly, but the generation of oxygen vacancies considerably increases the electrical sensitivity of the Er2O3 dielectric.

Physics Division annual review, 1 April 1980-31 March 1981

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-06-01

Progress in nuclear physics research is reported in the following areas: medium-energy physics (pion reaction mechanisms, high-resolution studies and nuclear structure, and two-nucleon physics with pions and electrons); heavy-ion research at the tandem and superconducting linear accelerator (resonant structure in heavy-ion reactions, fusion cross sections, high angular momentum states in nuclei, and reaction mechanisms and distributions of reaction strengths); charged-particle research; neutron and photonuclear physics; theoretical physics (heavy-ion direct-reaction theory, nuclear shell theory and nuclear structure, nuclear matter and nuclear forces, intermediate-energy physics, microscopic calculations of high-energy collisions of heavy ions, and light ion direct reactions); the superconducting linac; acceleratormore » operations; and GeV electron linac. Progress in atomic and molecular physics research is reported in the following areas: dissociation and other interactions of energetic molecular ions in solid and gaseous targets, beam-foil research and collision dynamics of heavy ions, photoionization- photoelectron research, high-resolution laser rf spectroscopy with atomic and molecular beams, moessbauer effect research, and theoretical atomic physics. Studies on interactions of energetic particles with solids are also described. Publications are listed. (WHK)« less

Close encounters with DNA

PubMed Central

Maffeo, C.; Yoo, J.; Comer, J.; Wells, D. B.; Luan, B.; Aksimentiev, A.

2014-01-01

Over the past ten years, the all-atom molecular dynamics method has grown in the scale of both systems and processes amenable to it and in its ability to make quantitative predictions about the behavior of experimental systems. The field of computational DNA research is no exception, witnessing a dramatic increase in the size of systems simulated with atomic resolution, the duration of individual simulations and the realism of the simulation outcomes. In this topical review, we describe the hallmark physical properties of DNA from the perspective of all-atom simulations. We demonstrate the amazing ability of such simulations to reveal the microscopic physical origins of experimentally observed phenomena and we review the frustrating limitations associated with imperfections of present atomic force fields and inadequate sampling. The review is focused on the following four physical properties of DNA: effective electric charge, response to an external mechanical force, interaction with other DNA molecules and behavior in an external electric field. PMID:25238560

Close encounters with DNA.

PubMed

Maffeo, C; Yoo, J; Comer, J; Wells, D B; Luan, B; Aksimentiev, A

2014-10-15

Over the past ten years, the all-atom molecular dynamics method has grown in the scale of both systems and processes amenable to it and in its ability to make quantitative predictions about the behavior of experimental systems. The field of computational DNA research is no exception, witnessing a dramatic increase in the size of systems simulated with atomic resolution, the duration of individual simulations and the realism of the simulation outcomes. In this topical review, we describe the hallmark physical properties of DNA from the perspective of all-atom simulations. We demonstrate the amazing ability of such simulations to reveal the microscopic physical origins of experimentally observed phenomena. We also discuss the frustrating limitations associated with imperfections of present atomic force fields and inadequate sampling. The review is focused on the following four physical properties of DNA: effective electric charge, response to an external mechanical force, interaction with other DNA molecules and behavior in an external electric field.

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms

PubMed Central

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; (Lamar) Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-01-01

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future. PMID:28181593

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms.

PubMed

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; Lamar Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-02-09

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future.

Enhanced optical nonlinearity and fiber-optical frequency comb controlled by a single atom in a whispering-gallery-mode microtoroid resonator

NASA Astrophysics Data System (ADS)

Li, Jiahua; Zhang, Suzhen; Yu, Rong; Zhang, Duo; Wu, Ying

2014-11-01

Based on a single atom coupled to a fiber-coupled, chip-based microresonator [B. Dayan et al., Science 319, 1062 (2008), 10.1126/science.1152261], we put forward a scheme to generate optical frequency combs at driving laser powers as low as a few nanowatts. Using state-of-the-art experimental parameters, we investigate in detail the influences of different atomic positions and taper-resonator coupling regimes on optical-frequency-comb generation. In addition to numerical simulations demonstrating this effect, a physical explanation of the underlying mechanism is presented. We find that the combination of the atom and the resonator can induce a large third-order nonlinearity which is significantly stronger than Kerr nonlinearity in Kerr frequency combs. Such enhanced nonlinearity can be used to generate optical frequency combs if driven with two continuous-wave control and probe lasers and significantly reduce the threshold of nonlinear optical processes. The comb spacing can be well tuned by changing the frequency beating between the driving control and probe lasers. The proposed method is versatile and can be adopted to different types of resonators, such as microdisks, microspheres, microtoroids or microrings.

Recent Development of IMP LECR3 Ion Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Z.M.; Zhao, H.W.; Li, J.Y.

2005-03-15

18GHz microwave has been fed to the LECR3 ion source to produce intense highly charged ion beams although this ion source was designed for 14.5GHz. Then 1.1 emA Ar8+ and 325 e{mu}A Ar11+ were obtained at 18GHz. During the source running for atomic physics experiment, some higher charge state ion beams such as Ar17+ and Ar18+ were detected and have been validated by atomic physics method. Furthermore, a few special gases, e.g. SiH4 and SF6, were tested on LECR3 ion source to produce required ion beams to satisfy the requirements of atomic physics experiments.

Theoretical and experimental studies in ultraviolet solar physics

NASA Technical Reports Server (NTRS)

Parkinson, W. H.; Reeves, E. M.

1975-01-01

The processes and parameters in atomic and molecular physics that are relevant to solar physics are investigated. The areas covered include: (1) measurement of atomic and molecular parameters that contribute to discrete and continous sources of opacity and abundance determinations in the sun; (2) line broadening and scattering phenomena; and (3) development of an ion beam spectroscopic source which is used for the measurement of electron excitation cross sections of transition region and coronal ions.

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.

Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights

DOE PAGES

Lii-Rosales, Ann; Han, Yong; Evans, James W.; ...

2018-02-06

Here in this paper, we present an extensive experimental study of the conditions under which Cu forms encapsulated islands under the top surface layers of graphite, as a result of physical vapor deposition of Cu on argon-ion-bombarded graphite. When the substrate is held at 800 K during deposition, conditions are optimal for formation of encapsulated multilayer Cu islands. Deposition temperatures below 600 K favor adsorbed Cu clusters, while deposition temperatures above 800 K favor a different type of feature that is probably a single-layer intercalated Cu island. The multilayer Cu islands are characterized with respect to size and shape, thicknessmore » and continuity of the graphitic overlayer, relationship to graphite steps, and stability in air. The experimental techniques are scanning tunneling microscopy and X-ray photoelectron spectroscopy. We also present an extensive study using density functional theory to compare stabilities of a wide variety of configurations of Cu atoms, Cu clusters, and Cu layers on/under the graphite surface. The only configuration that is significantly more stable under the graphite surface than on top of it, is a single Cu atom. This analysis leads us to conclude that formation of encapsulated Cu islands is kinetically driven, rather than thermodynamically driven.« less

Order parameter aided efficient phase space exploration under extreme conditions

NASA Astrophysics Data System (ADS)

Samanta, Amit

Physical processes in nature exhibit disparate time-scales, for example time scales associated with processes like phase transitions, various manifestations of creep, sintering of particles etc. are often much higher than time the system spends in the metastable states. The transition times associated with such events are also orders of magnitude higher than time-scales associated with vibration of atoms. Thus, an atomistic simulation of such transition events is a challenging task. Consequently, efficient exploration of configuration space and identification of metastable structures in condensed phase systems is challenging. In this talk I will illustrate how we can define a set of coarse-grained variables or order parameters and use these to systematically and efficiently steer a system containing thousands or millions of atoms over different parts of the configuration. This order parameter aided sampling can be used to identify metastable states, transition pathways and understand the mechanistic details of complex transition processes. I will illustrate how this sampling scheme can be used to study phase transition pathways and phase boundaries in prototypical materials, like SiO2 and Cu under high-pressure conditions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Formation of Multilayer Cu Islands Embedded beneath the Surface of Graphite: Characterization and Fundamental Insights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lii-Rosales, Ann; Han, Yong; Evans, James W.

Here in this paper, we present an extensive experimental study of the conditions under which Cu forms encapsulated islands under the top surface layers of graphite, as a result of physical vapor deposition of Cu on argon-ion-bombarded graphite. When the substrate is held at 800 K during deposition, conditions are optimal for formation of encapsulated multilayer Cu islands. Deposition temperatures below 600 K favor adsorbed Cu clusters, while deposition temperatures above 800 K favor a different type of feature that is probably a single-layer intercalated Cu island. The multilayer Cu islands are characterized with respect to size and shape, thicknessmore » and continuity of the graphitic overlayer, relationship to graphite steps, and stability in air. The experimental techniques are scanning tunneling microscopy and X-ray photoelectron spectroscopy. We also present an extensive study using density functional theory to compare stabilities of a wide variety of configurations of Cu atoms, Cu clusters, and Cu layers on/under the graphite surface. The only configuration that is significantly more stable under the graphite surface than on top of it, is a single Cu atom. This analysis leads us to conclude that formation of encapsulated Cu islands is kinetically driven, rather than thermodynamically driven.« less

Anomalous compression behavior of ˜12 nm nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Wang, Qiming; Li, Shourui; Peng, Fang; Lei, Li; Hu, Qiwei; Wang, Pei; Nan, Xiaolong; Liu, Jing; Zhu, Wenjun; He, Duanwei

2017-06-01

When the grain size decreases, there inevitably exists a critical size (dc) where the contribution of surface atoms to the physical properties is competitive with that of the interior atoms, giving rise to a wide variety of new phenomena. The behavior of granular materials near dc is particularly interesting because of the crossover, a continuous transition from one type of mechanism to another. In situ high-pressure x-ray diffraction experiments showed that the compression curve of nanocrystalline anatase TiO2 with grain size near dc reached a platform after about 5%-6% of deformation under hydrostatic compression. Eventually, the unit cell volume of anatase expanded at ˜14-16 GPa. We propose that the anomalous compression behavior is attributed to the formation and thickening of the stiff high density amorphous shell under high pressure, giving rise to a great arching effect at the grain boundary at the nanolevel. This process results in a remarkable difference in stress between inside and outside of the shell, generating the illusions of the hardening and the negative compressibility. This study offers a new insight into the mechanical properties of nanomaterials under extreme conditions.

Subsumed complexity: abiogenesis as a by-product of complex energy transduction.

PubMed

Adam, Z R; Zubarev, D; Aono, M; Cleaves, H James

2017-12-28

The origins of life bring into stark relief the inadequacy of our current synthesis of thermodynamic, chemical, physical and information theory to predict the conditions under which complex, living states of organic matter can arise. Origins research has traditionally proceeded under an array of implicit or explicit guiding principles in lieu of a universal formalism for abiogenesis. Within the framework of a new guiding principle for prebiotic chemistry called subsumed complexity , organic compounds are viewed as by-products of energy transduction phenomena at different scales (subatomic, atomic, molecular and polymeric) that retain energy in the form of bonds that inhibit energy from reaching the ground state. There is evidence for an emergent level of complexity that is overlooked in most conceptualizations of abiogenesis that arises from populations of compounds formed from atomic energy input. We posit that different forms of energy input can exhibit different degrees of dissipation complexity within an identical chemical medium. By extension, the maximum capacity for organic chemical complexification across molecular and macromolecular scales subsumes, rather than emerges from, the underlying complexity of energy transduction processes that drive their production and modification.This article is part of the themed issue 'Reconceptualizing the origins of life'. © 2017 The Author(s).

Subsumed complexity: abiogenesis as a by-product of complex energy transduction

NASA Astrophysics Data System (ADS)

Adam, Z. R.; Zubarev, D.; Aono, M.; Cleaves, H. James

2017-11-01

The origins of life bring into stark relief the inadequacy of our current synthesis of thermodynamic, chemical, physical and information theory to predict the conditions under which complex, living states of organic matter can arise. Origins research has traditionally proceeded under an array of implicit or explicit guiding principles in lieu of a universal formalism for abiogenesis. Within the framework of a new guiding principle for prebiotic chemistry called subsumed complexity, organic compounds are viewed as by-products of energy transduction phenomena at different scales (subatomic, atomic, molecular and polymeric) that retain energy in the form of bonds that inhibit energy from reaching the ground state. There is evidence for an emergent level of complexity that is overlooked in most conceptualizations of abiogenesis that arises from populations of compounds formed from atomic energy input. We posit that different forms of energy input can exhibit different degrees of dissipation complexity within an identical chemical medium. By extension, the maximum capacity for organic chemical complexification across molecular and macromolecular scales subsumes, rather than emerges from, the underlying complexity of energy transduction processes that drive their production and modification. This article is part of the themed issue 'Reconceptualizing the origins of life'.

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…

From Lattice Boltzmann to hydrodynamics in dissipative relativistic fluids

NASA Astrophysics Data System (ADS)

Gabbana, Alessandro; Mendoza, Miller; Succi, Sauro; Tripiccione, Raffaele

2017-11-01

Relativistic fluid dynamics is currently applied to several fields of modern physics, covering many physical scales, from astrophysics, to atomic scales (e.g. in the study of effective 2D systems such as graphene) and further down to subnuclear scales (e.g. quark-gluon plasmas). This talk focuses on recent progress in the largely debated connection between kinetic transport coefficients and macroscopic hydrodynamic parameters in dissipative relativistic fluid dynamics. We use a new relativistic Lattice Boltzmann method (RLBM), able to handle from ultra-relativistic to almost non-relativistic flows, and obtain strong evidence that the Chapman-Enskog expansion provides the correct pathway from kinetic theory to hydrodynamics. This analysis confirms recently obtained theoretical results, which can be used to obtain accurate calibrations for RLBM methods applied to realistic physics systems in the relativistic regime. Using this calibration methodology, RLBM methods are able to deliver improved physical accuracy in the simulation of the physical systems described above. European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 642069.

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.

Interacting dark resonances with plasmonic meta-molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jha, Pankaj K.; Mrejen, Michael; Kim, Jeongmin

2014-09-15

Dark state physics has led to a variety of remarkable phenomena in atomic physics, quantum optics, and information theory. Here, we investigate interacting dark resonance type physics in multi-layered plasmonic meta-molecules. We theoretically demonstrate that these plasmonic meta-molecules exhibit sub-natural spectral response, analogous to conventional atomic four-level configuration, by manipulating the evanescent coupling between the bright and dark elements (plasmonic atoms). Using cascaded coupling, we show nearly 4-fold reduction in linewidth of the hybridized resonance compared to a resonantly excited single bright plasmonic atom with same absorbance. In addition, we engineered the geometry of the meta-molecules to realize efficient intramolecularmore » excitation transfer with nearly 80%, on resonant excitation, of the total absorption being localized at the second dark plasmonic atom. An analytical description of the spectral response of the structure is presented with full electrodynamics simulations to corroborate our results. Such multilayered meta-molecules can bring a new dimension to higher quality factor plasmonic resonance, efficient excitation transfer, wavelength demultiplexing, and enhanced non-linearity at nanoscale.« less

PlasmaPy: initial development of a Python package for plasma physics

NASA Astrophysics Data System (ADS)

Murphy, Nicholas; Leonard, Andrew J.; Stańczak, Dominik; Haggerty, Colby C.; Parashar, Tulasi N.; Huang, Yu-Min; PlasmaPy Community

2017-10-01

We report on initial development of PlasmaPy: an open source community-driven Python package for plasma physics. PlasmaPy seeks to provide core functionality that is needed for the formation of a fully open source Python ecosystem for plasma physics. PlasmaPy prioritizes code readability, consistency, and maintainability while using best practices for scientific computing such as version control, continuous integration testing, embedding documentation in code, and code review. We discuss our current and planned capabilities, including features presently under development. The development roadmap includes features such as fluid and particle simulation capabilities, a Grad-Shafranov solver, a dispersion relation solver, atomic data retrieval methods, and tools to analyze simulations and experiments. We describe several ways to contribute to PlasmaPy. PlasmaPy has a code of conduct and is being developed under a BSD license, with a version 0.1 release planned for 2018. The success of PlasmaPy depends on active community involvement, so anyone interested in contributing to this project should contact the authors. This work was partially supported by the U.S. Department of Energy.

Hidden symmetries in plasmonic gratings

NASA Astrophysics Data System (ADS)

Huidobro, P. A.; Chang, Y. H.; Kraft, M.; Pendry, J. B.

2017-04-01

Plasmonic gratings constitute a paradigmatic instance of the wide range of applications enabled by plasmonics. While subwavelength metal gratings find applications in optical biosensing and photovoltaics, atomically thin gratings achieved by periodically doping a graphene monolayer perform as metasurfaces for the control of terahertz radiation. In this paper we show how these two instances of plasmonic gratings inherit their spectral properties from an underlying slab with translational symmetry. We develop an analytical formalism to accurately derive the mode spectrum of the gratings that provides a great physical insight.

One-electron propagation in Fermi, Pasta, Ulam disordered chains with Gaussian acoustic pulse pumping

NASA Astrophysics Data System (ADS)

Silva, L. D. Da; Dos Santos, J. L. L.; Ranciaro Neto, A.; Sales, M. O.; de Moura, F. A. B. F.

In this work, we consider a one-electron moving on a Fermi, Pasta, Ulam disordered chain under effect of electron-phonon interaction and a Gaussian acoustic pulse pumping. We describe electronic dynamics using quantum mechanics formalism and the nonlinear atomic vibrations using standard classical physics. Solving numerical equations related to coupled quantum/classical behavior of this system, we study electronic propagation properties. Our calculations suggest that the acoustic pumping associated with the electron-lattice interaction promote a sub-diffusive electronic dynamics.

Applications of atom interferometry - from ground to space

NASA Astrophysics Data System (ADS)

Schubert, Christian; Rasel, Ernst Maria; Gaaloul, Naceur; Ertmer, Wolfgang

2016-07-01

Atom interferometry is utilized for the measurement of rotations [1], accelerations [2] and for tests of fundamental physics [3]. In these devices, three laser light pulses separated by a free evolution time coherently manipulate the matter waves which resembles the Mach-Zehnder geometry in optics. Atom gravimeters demonstrated an accuracy of few microgal [2,4], and atom gradiometers showed a noise floor of 30 E Hz^{-1/2} [5]. Further enhancements of atom interferometers are anticipated by the integration of novel source concepts providing ultracold atoms, extending the free fall time of the atoms, and enhanced techniques for coherent manipulation. Sources providing Bose-Einstein condensates recently demontrated a flux compatible with precision experiments [6]. All of these aspects are studied in the transportable quantum gravimeter QG-1 and the very long baseline atom interferometry teststand in Hannover [7] with the goal of surpassing the microgal regime. Going beyond ground based setups, the QUANTUS collaboration exploits the unique features of a microgravity environment in drop tower experiments [8] and in a sounding rocket mission. The payloads are compact and robust atom optics experiments based on atom chips [6], enabling technology for transportable sensors on ground as a byproduct. More prominently, they are pathfinders for proposed satellite missions as tests of the universality of free fall [9] and gradiometry based on atom interferometers [10]. 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 50WM1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] PRL 114 063002 2015 [2] Nature 400 849 1999 [3] PRL 112 203002 2014 [4] NJP 13 065026 2011 [5] PRA 65 033608 2002 [6] NJP 17 065001 2015 [7] NJP 17 035011 2015 [8] PRL 110 093602 2013 [9] CQG 31 115010 2014 [10] MST 26 139 2014.

The impact of recent advances in laboratory astrophysics on our understanding of the cosmos.

PubMed

Savin, D W; Brickhouse, N S; Cowan, J J; Drake, R P; Federman, S R; Ferland, G J; Frank, A; Gudipati, M S; Haxton, W C; Herbst, E; Profumo, S; Salama, F; Ziurys, L M; Zweibel, E G

2012-03-01

An emerging theme in modern astrophysics is the connection between astronomical observations and the underlying physical phenomena that drive our cosmos. Both the mechanisms responsible for the observed astrophysical phenomena and the tools used to probe such phenomena-the radiation and particle spectra we observe-have their roots in atomic, molecular, condensed matter, plasma, nuclear and particle physics. Chemistry is implicitly included in both molecular and condensed matter physics. This connection is the theme of the present report, which provides a broad, though non-exhaustive, overview of progress in our understanding of the cosmos resulting from recent theoretical and experimental advances in what is commonly called laboratory astrophysics. This work, carried out by a diverse community of laboratory astrophysicists, is increasingly important as astrophysics transitions into an era of precise measurement and high fidelity modeling.

Concept for room temperature single-spin tunneling force microscopy with atomic spatial resolution

NASA Astrophysics Data System (ADS)

Payne, Adam

A study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single electron tunneling between two electrically isolated paramagnetic states. Single-spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured atomic force microscopy (AFM) system noise. The results show that the approach could provide single-spin measurement of electrically isolated defect states with atomic spatial resolution at room temperature.

Atomic-resolution single-spin magnetic resonance detection concept based on tunneling force microscopy

NASA Astrophysics Data System (ADS)

Payne, A.; Ambal, K.; Boehme, C.; Williams, C. C.

2015-05-01

A study of a force detected single-spin magnetic resonance measurement concept with atomic spatial resolution is presented. The method is based upon electrostatic force detection of spin-selection rule controlled single-electron tunneling between two electrically isolated paramagnetic states. Single-spin magnetic resonance detection is possible by measuring the force detected tunneling charge noise on and off spin resonance. Simulation results of this charge noise, based upon physical models of the tunneling and spin physics, are directly compared to measured atomic force microscopy system noise. The results show that the approach could provide single-spin measurement of electrically isolated qubit states with atomic spatial resolution at room temperature.

Atomic Poetry: Using Poetry To Teach Rutherford's Discovery of the Nucleus.

ERIC Educational Resources Information Center

Abisdris, Gil; Casuga, Adele

2001-01-01

Points out how Rutherford's discovery of the nucleus changed ideas about the structure of the atom and influenced poetry. Uses Robert Frost's poems "Version" and "The Secret Sits" to teach a physical science class about atomic theory. (YDS)

Collision of impurities with Bose–Einstein condensates

NASA Astrophysics Data System (ADS)

Lingua, F.; Lepori, L.; Minardi, F.; Penna, V.; Salasnich, L.

2018-04-01

Quantum dynamics of impurities in a bath of bosons is a long-standing problem in solid-state, plasma, and atomic physics. Recent experimental and theoretical investigations with ultracold atoms have focused on this problem, studying atomic impurities immersed in an atomic Bose–Einstein condensate (BEC) and for various relative coupling strengths tuned by the Fano‑Feshbach resonance technique. Here, we report extensive numerical simulations on a closely related problem: the collision between a bosonic impurity consisting of a few 41K atoms and a BEC of 87Rb atoms in a quasi one-dimensional configuration and under a weak harmonic axial confinement. For small values of the inter-species interaction strength (regardless of its sign), we find that the impurity, which starts from outside the BEC, simply causes the BEC cloud to oscillate back and forth, but the frequency of oscillation depends on the interaction strength. For intermediate couplings, after a few cycles of oscillation the impurity is captured by the BEC, and strongly changes its amplitude of oscillation. In the strong interaction regime, if the inter-species interaction is attractive, a local maximum (bright soliton) in the BEC density occurs where the impurity is trapped; if, instead, the inter-species interaction is repulsive, the impurity is not able to enter the BEC cloud and the reflection coefficient is close to one. However, if the initial displacement of the impurity is increased, the impurity is able to penetrate the cloud, leading to the appearance of a moving hole (dark soliton) in the BEC.

Analysis of Adhesive Characteristics of Asphalt Based on Atomic Force Microscopy and Molecular Dynamics Simulation.

PubMed

Xu, Meng; Yi, Junyan; Feng, Decheng; Huang, Yudong; Wang, Dongsheng

2016-05-18

Asphalt binder is a very important building material in infrastructure construction; it is commonly mixed with mineral aggregate and used to produce asphalt concrete. Owing to the large differences in physical and chemical properties between asphalt and aggregate, adhesive bonds play an important role in determining the performance of asphalt concrete. Although many types of adhesive bonding mechanisms have been proposed to explain the interaction forces between asphalt binder and mineral aggregate, few have been confirmed and characterized. In comparison with chemical interactions, physical adsorption has been considered to play a more important role in adhesive bonding between asphalt and mineral aggregate. In this study, the silicon tip of an atomic force microscope was used to represent silicate minerals in aggregate, and a nanoscale analysis of the characteristics of adhesive bonding between asphalt binder and the silicon tip was conducted via an atomic force microscopy (AFM) test and molecular dynamics (MD) simulations. The results of the measurements and simulations could help in better understanding of the bonding and debonding procedures in asphalt-aggregate mixtures during hot mixing and under traffic loading. MD simulations on a single molecule of a component of asphalt and monocrystalline silicon demonstrate that molecules with a higher atomic density and planar structure, such as three types of asphaltene molecules, can provide greater adhesive strength. However, regarding the real components of asphalt binder, both the MD simulations and AFM test indicate that the colloidal structural behavior of asphalt also has a large influence on the adhesion behavior between asphalt and silicon. A schematic model of the interaction between asphalt and silicon is presented, which can explain the effect of aging on the adhesion behavior of asphalt.

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.

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…

Willis Lamb, Jr., the Hydrogen Atom, and the Lamb Shift

Science.gov Websites

1955, Lamb won the Nobel Prize in Physics for his discoveries concerning "the fine structure of , May 7 - September 30, 1979 Fine Structure of the Hydrogen Atom, Part I; Part II; Part III; Part IV ; Part V; Part VI (from Physical Review 1950-1953) Microwave Technique for Determining the Fine Structure

Bose-Einstein Condensates in 1D Optical Lattices: Nonlinearity and Wannier-Stark Spectra

NASA Astrophysics Data System (ADS)

Arimondo, Ennio; Ciampini, Donatella; Morsch, Oliver

The development of powerful laser cooling and trapping techniques has made possible the controlled realization of dense and cold gaseous samples, thus opening the way for investigations in the ultracold temperature regimes not accessible with conventional techniques. A Bose-Einstein condensate (BEC) represents a peculiar gaseous state where all the particles reside in the same quantum mechanical state. Therefore BECs exhibit quantum mechanical phe-nomena on a macroscopic scale with a single quantum mechanical wavefunction describing the external degrees of freedom. That control of the external degrees of freedom is combined with a precise control of the internal degrees. The BEC investigation has become a very active area of research in contem-porary physics. The BEC study encompasses different subfields of physics, i.e., atomic and molecular physics, quantum optics, laser spectroscopy, solid state physics. Atomic physics and laser spectroscopy provide the methods for creating and manipulating the atomic and molecular BECs. However owing to the interactions between the particles composing the condensate and to the configuration of the external potential, concepts and methods from solid state physics are extensively used for BEC description.

Preliminary Evaluation of Atomization Characteristics of Improved Biodiesel for Gas Turbine Application

NASA Astrophysics Data System (ADS)

Kumaran, P.; Gopinathan, M.; Razali, N. M.; Kuperjans, Isabel; Hariffin, B.; Hamdan, H.

2013-06-01

Biodiesel is one of the clean burning alternative fuels derived from natural resources and animal fats which is promising fuel for gas turbine application. However, inferior properties of biodiesel such as high viscosity, density and surface tension results in inferior atomization and high emission, hence impedes the fuel compatible for gas turbine application and emits slightly higher emission pollutants due to inferior atomization. This research work focuses on preliminary evaluation of the atomization characteristics of derived from Malaysian waste cooking oil which is the physical properties are subsequently improved by a microwave assisted post treatment scheme. The results shows with improvement in physical properties achieved through the post treatment, biodiesel exhibits significantly better atomization characteristics in terms of spray angle, spray length, sauter mean diameter and shorter evaporation time compared to the biodiesel before improvement and fossil diesel.

Atomic Data in X-Ray Astrophysics

NASA Technical Reports Server (NTRS)

Brickhouse, N. S.

2000-01-01

With the launches of the Chandra X-ray Observatory (CXO) and the X-ray Multimirror Mission (XMM) and the upcoming launch of the Japanese mission ASTRO-E, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources will provide not only invaluable calibration data, but will also give us benchmarks for the atomic data under collisional equilibrium conditions. Analysis of the Chandra X-ray Observatory data, and data from other telescopes taken simultaneously, for these stars is ongoing as part of the Emission Line Project. Goals of the Emission Line Project are: (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. The Astrophysical Plasma Emission Database will be described in some detail, as it is introducing standardization and flexibility into X-ray spectral modeling. Spectral models of X-ray astrophysical plasmas can be generally classified as dominated by either collisional ionization or by X-ray photoionization. While the atomic data needs for spectral models under these two types of ionization are significantly different, there axe overlapping data needs, as I will describe. Early results from the Emission Line Project benchmarks are providing an invaluable starting place, but continuing work to improve the accuracy and completeness of atomic data is needed. Additionally, we consider the possibility that some sources will require that both collisional ionization and photoionization be taken into account, or that time-dependent ionization be considered. Thus plasma spectral models of general use need to be computed over a wide range of physical conditions.

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.

Optical Pattern Formation in Cold Atoms: Explaining the Red-Blue Asymmetry

NASA Astrophysics Data System (ADS)

Schmittberger, Bonnie; Gauthier, Daniel

2013-05-01

The study of pattern formation in atomic systems has provided new insight into fundamental many-body physics and low-light-level nonlinear optics. Pattern formation in cold atoms in particular is of great interest in condensed matter physics and quantum information science because atoms undergo self-organization at ultralow input powers. We recently reported the first observation of pattern formation in cold atoms but found that our results were not accurately described by any existing theoretical model of pattern formation. Previous models describing pattern formation in cold atoms predict that pattern formation should occur using both red and blue-detuned pump beams, favoring a lower threshold for blue detunings. This disagrees with our recent work, in which we only observed pattern formation with red-detuned pump beams. Previous models also assume a two-level atom, which cannot account for the cooling processes that arise when beams counterpropagate through a cold atomic vapor. We describe a new model for pattern formation that accounts for Sisyphus cooling in multi-level atoms, which gives rise to a new nonlinearity via spatial organization of the atoms. This spatial organization causes a sharp red-blue detuning asymmetry, which agrees well with our experimental observations. We gratefully acknowledge the financial support of the NSF through Grant #PHY-1206040.

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.

Oxidation-driven surface dynamics on NiAl(100)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Hailang; Chen, Xidong; Li, Liang

Atomic steps, a defect common to all crystal surfaces, can play an important role in many physical and chemical processes. However, attempts to predict surface dynamics under nonequilibrium conditions are usually frustrated by poor knowledge of the atomic processes of surface motion arising from mass transport from/to surface steps. Using low-energy electron microscopy that spatially and temporally resolves oxide film growth during the oxidation of NiAl(100) we demonstrate that surface steps are impermeable to oxide film growth. The advancement of the oxide occurs exclusively on the same terrace and requires the coordinated migration of surface steps. The resulting piling upmore » of surface steps ahead of the oxide growth front progressively impedes the oxide growth. This process is reversed during oxide decomposition. The migration of the substrate steps is found to be a surface-step version of the well-known Hele-Shaw problem, governed by detachment (attachment) of Al atoms at step edges induced by the oxide growth (decomposition). As a result, by comparing with the oxidation of NiAl(110) that exhibits unimpeded oxide film growth over substrate steps, we suggest that whenever steps are the source of atoms used for oxide growth they limit the oxidation process; when atoms are supplied from the bulk, the oxidation rate is not limited by the motion of surface steps.« less

Oxidation-driven surface dynamics on NiAl(100)

DOE PAGES

Qin, Hailang; Chen, Xidong; Li, Liang; ...

2014-12-29

Atomic steps, a defect common to all crystal surfaces, can play an important role in many physical and chemical processes. However, attempts to predict surface dynamics under nonequilibrium conditions are usually frustrated by poor knowledge of the atomic processes of surface motion arising from mass transport from/to surface steps. Using low-energy electron microscopy that spatially and temporally resolves oxide film growth during the oxidation of NiAl(100) we demonstrate that surface steps are impermeable to oxide film growth. The advancement of the oxide occurs exclusively on the same terrace and requires the coordinated migration of surface steps. The resulting piling upmore » of surface steps ahead of the oxide growth front progressively impedes the oxide growth. This process is reversed during oxide decomposition. The migration of the substrate steps is found to be a surface-step version of the well-known Hele-Shaw problem, governed by detachment (attachment) of Al atoms at step edges induced by the oxide growth (decomposition). As a result, by comparing with the oxidation of NiAl(110) that exhibits unimpeded oxide film growth over substrate steps, we suggest that whenever steps are the source of atoms used for oxide growth they limit the oxidation process; when atoms are supplied from the bulk, the oxidation rate is not limited by the motion of surface steps.« less

Motion of W and He atoms during formation of W fuzz

NASA Astrophysics Data System (ADS)

Doerner, R. P.; Nishijima, D.; Krasheninnikov, S. I.; Schwarz-Selinger, T.; Zach, M.

2018-06-01

Measurements are conducted to identify the motion of tungsten and helium atoms during the formation of tungsten fuzz. In a first series of experiments the mobility of helium within the growing fuzz was measured by adding 3He to the different stages of plasma exposure under conditions that promoted tungsten fuzz growth. Ion beam analysis was used to quantify the amount of 3He remaining in the samples following the plasma exposure. The results indicate that the retention of helium in bubbles within tungsten is a dynamic process with direct implantation rather than diffusion into the bubbles, best describing the motion of the helium atoms. In the second experiment, an isotopically enriched layer of tungsten (~92.99% 182W) is deposited on the surface of a bulk tungsten sample with the natural abundance of the isotopes. This sample is then exposed to helium plasma at the conditions necessary to support the formation of tungsten ‘fuzz’. Depth profiles of the concentration of each of the tungsten isotopes are obtained using secondary ion mass spectrometry (SIMS) before and after the plasma exposure. The depth profiles clearly show mixing of tungsten atoms from the bulk sample toward the surface of the fuzz. This supports a physical picture of the dynamic behavior of helium bubbles which, also, causes an enhanced mixing of tungsten atoms.

Preface: Special Topic on Atomic and Molecular Layer Processing: Deposition, Patterning, and Etching

NASA Astrophysics Data System (ADS)

Engstrom, James R.; Kummel, Andrew C.

2017-02-01

Thin film processing technologies that promise atomic and molecular scale control have received increasing interest in the past several years, as traditional methods for fabrication begin to reach their fundamental limits. Many of these technologies involve at their heart phenomena occurring at or near surfaces, including adsorption, gas-surface reactions, diffusion, desorption, and re-organization of near-surface layers. Moreover many of these phenomena involve not just reactions occurring under conditions of local thermodynamic equilibrium but also the action of energetic species including electrons, ions, and hyperthermal neutrals. There is a rich landscape of atomic and molecular scale interactions occurring in these systems that is still not well understood. In this Special Topic Issue of The Journal of Chemical Physics, we have collected recent representative examples of work that is directed at unraveling the mechanistic details concerning atomic and molecular layer processing, which will provide an important framework from which these fields can continue to develop. These studies range from the application of theory and computation to these systems to the use of powerful experimental probes, such as X-ray synchrotron radiation, probe microscopies, and photoelectron and infrared spectroscopies. The work presented here helps in identifying some of the major challenges and direct future activities in this exciting area of research involving atomic and molecular layer manipulation and fabrication.

Preface: Special Topic on Atomic and Molecular Layer Processing: Deposition, Patterning, and Etching.

PubMed

Engstrom, James R; Kummel, Andrew C

2017-02-07

Thin film processing technologies that promise atomic and molecular scale control have received increasing interest in the past several years, as traditional methods for fabrication begin to reach their fundamental limits. Many of these technologies involve at their heart phenomena occurring at or near surfaces, including adsorption, gas-surface reactions, diffusion, desorption, and re-organization of near-surface layers. Moreover many of these phenomena involve not just reactions occurring under conditions of local thermodynamic equilibrium but also the action of energetic species including electrons, ions, and hyperthermal neutrals. There is a rich landscape of atomic and molecular scale interactions occurring in these systems that is still not well understood. In this Special Topic Issue of The Journal of Chemical Physics, we have collected recent representative examples of work that is directed at unraveling the mechanistic details concerning atomic and molecular layer processing, which will provide an important framework from which these fields can continue to develop. These studies range from the application of theory and computation to these systems to the use of powerful experimental probes, such as X-ray synchrotron radiation, probe microscopies, and photoelectron and infrared spectroscopies. The work presented here helps in identifying some of the major challenges and direct future activities in this exciting area of research involving atomic and molecular layer manipulation and fabrication.

Motion of W and He atoms during formation of W fuzz

DOE PAGES

Doerner, R. P.; Nishijima, D.; Krasheninnikov, S. I.; ...

2018-04-11

Measurements are conducted to identify the motion of tungsten and helium atoms during the formation of tungsten fuzz. In a first series of experiments the mobility of helium within the growing fuzz was measured by adding 3He to the different stages of plasma exposure under conditions that promoted tungsten fuzz growth. Ion beam analysis was used to quantify the amount of 3He remaining in the samples following the plasma exposure. The results indicate that the retention of helium in bubbles within tungsten is a dynamic process with direct implantation rather than diffusion into the bubbles, best describing the motion ofmore » the helium atoms. In the second experiment, an isotopically enriched layer of tungsten (~92.99% 182W) is deposited on the surface of a bulk tungsten sample with the natural abundance of the isotopes. This sample is then exposed to helium plasma at the conditions necessary to support the formation of tungsten 'fuzz'. Depth profiles of the concentration of each of the tungsten isotopes are obtained using secondary ion mass spectrometry (SIMS) before and after the plasma exposure. The depth profiles clearly show mixing of tungsten atoms from the bulk sample toward the surface of the fuzz. Lastly, this supports a physical picture of the dynamic behavior of helium bubbles which, also, causes an enhanced mixing of tungsten atoms.« less

Generalized nonlinear Schrödinger equation and ultraslow optical solitons in a cold four-state atomic system.

PubMed

Hang, Chao; Huang, Guoxiang; Deng, L

2006-03-01

We investigate the influence of high-order dispersion and nonlinearity on the propagation of ultraslow optical solitons in a lifetime broadened four-state atomic system under a Raman excitation. Using a standard method of multiple-scales we derive a generalized nonlinear Schrödinger equation and show that for realistic physical parameters and at the pulse duration of 10(-6)s, the effects of third-order linear dispersion, nonlinear dispersion, and delay in nonlinear refractive index can be significant and may not be considered as perturbations. We provide exact soliton solutions for the generalized nonlinear Schrödinger equation and demonstrate that optical solitons obtained may still have ultraslow propagating velocity. Numerical simulations on the stability and interaction of these ultraslow optical solitons in the presence of linear and differential absorptions are also presented.

The Interstellar Medium in External Galaxies: Summaries of contributed papers

NASA Technical Reports Server (NTRS)

Hollenbach, David J. (Editor); Thronson, Harley A., Jr. (Editor)

1990-01-01

The Second Wyoming Conference entitled, The Interstellar Medium in External Galaxies, was held on July 3 to 7, 1989, to discuss the current understanding of the interstellar medium in external galaxies and to analyze the basic physical processes underlying interstellar phenomena. The papers covered a broad range of research on the gas and dust in external galaxies and focused on such topics as the distribution and morphology of the atomic, molecular, and dust components; the dynamics of the gas and the role of the magnetic field in the dynamics; elemental abundances and gas depletions in the atomic and ionized components; cooling flows; star formation; the correlation of the nonthermal radio continuum with the cool component of the interstellar medium; the origin and effect of hot galactic halos; the absorption line systems seen in distant quasars; and the effect of galactic collisions.

Effect of Annealing Temperature and Oxygen Flow in the Properties of Ion Beam Sputtered SnO-₂x Thin Films.

PubMed

Wang, Chun-Min; Huang, Chun-Chieh; Kuo, Jui-Chao; Sahu, Dipti Ranjan; Huang, Jow-Lay

2015-08-14

Tin oxide (SnO 2-x ) thin films were prepared under various flow ratios of O₂/(O₂ + Ar) on unheated glass substrate using the ion beam sputtering (IBS) deposition technique. This work studied the effects of the flow ratio of O₂/(O₂ + Ar), chamber pressures and post-annealing treatment on the physical properties of SnO₂ thin films. It was found that annealing affects the crystal quality of the films as seen from both X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. In addition, the surface RMS roughness was measured with atomic force microscopy (AFM). Auger electron spectroscopy (AES) analysis was used to obtain the changes of elemental distribution between tin and oxygen atomic concentration. The electrical property is discussed with attention to the structure factor.

Elliptic flow from Coulomb interaction and low density elastic scattering

NASA Astrophysics Data System (ADS)

Sun, Yuliang; Li, Qingfeng; Wang, Fuqiang

2018-04-01

In high energy heavy ion collisions and interacting cold atom systems, large elliptic flow anisotropies have been observed. For the large opacity (ρ σ L ˜103 ) of the latter hydrodynamics is a natural consequence, but for the small opacity (ρ σ L ˜1 ) of the former the hydrodynamic description is questionable. To shed light onto the situation, we simulate the expansion of a low density argon ion (or atom) system, initially trapped in an elliptical region, under the Coulomb interaction (or elastic scattering). Significant elliptic anisotropy is found in both cases, and the anisotropy depends on the initial spatial eccentricity and the density of the system. The results may provide insights into the physics of anisotropic flow in high energy heavy ion collisions and its role in the study of quantum chromodynamics.

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.

An Overview of the Cooperative Effort between the United States Department of Energy and the China Atomic Energy Authority to Enhance MPC&A Inspections for Civil Nuclear Facilities in China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahern, Keith; Daming, Liu; Hanley, Tim

The United States Department of Energy, National Nuclear Security Administration (DOE/NNSA) and the China Atomic Energy Authority (CAEA) are cooperating to enhance the domestic regulatory inspections capacity for special nuclear material protection, control and accounting (MPC&A) requirements for civil nuclear facilities in China. This cooperation is conducted under the auspices of the Agreement between the Department of Energy of the United States of America and the State Development and Planning Commission of the People s Republic of China on Cooperation Concerning Peaceful Uses of Nuclear Technology. This initial successful effort was conducted in three phases. Phase I focused on introducingmore » CAEA personnel to DOE and U. S. Nuclear Regulatory Commission inspection methods for U. S. facilities. This phase was completed in January 2008 during meetings in Beijing. Phase II focused on developing physical protection and material control and accounting inspection exercises that enforced U. S. inspection methods identified during Phase 1. Hands on inspection activities were conducted in the United States over a two week period in July 2009. Simulated deficiencies were integrated into the inspection exercises. The U. S. and Chinese participants actively identified and discussed deficiencies noted during the two week training course. The material control and accounting inspection exercises were conducted at the Paducah Gaseous Diffusion Plant (PGDP) in Paducah, KY. The physical protection inspection exercises were conducted at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN. Phase III leveraged information provided under Phase I and experience gained under Phase II to develop a formal inspection guide that incorporates a systematic approach to training for Chinese MPC&A field inspectors. Additional hands on exercises that are applicable to Chinese regulations were incorporated into the Phase III training material. Phase III was completed in May 2010 at the China Institute of Atomic Energy (CIAE) in Beijing. This paper provides details of the successful cooperation between DOE/NNSA and CAEA for all phases of the cooperative effort to enhance civil domestic MPC&A inspections in China.« less

Charge transport in doped zigzag phosphorene nanoribbons

NASA Astrophysics Data System (ADS)

Nourbakhsh, Zahra; Asgari, Reza

2018-06-01

The effects of lattice distortion and chemical disorder on charge transport properties of two-terminal zigzag phosphorene nanoribbons (zPNRs), which shows resonant tunneling behavior under an electrical applied bias, are studied. Our comprehensive study is based on ab initio quantum transport calculations on the basis of the Landauer theory. We use nitrogen and silicon substitutional dopant atoms, and employ different physical quantities such as the I -V curve, voltage drop behavior, transmission spectrum, transmission pathway, and atomic current to explore the transport mechanism of zPNR devices under a bias voltage. The calculated transmission pathways show the transition from a ballistic transport regime to a diffusive and in some particular cases to localized transport regimes. Current flowing via the chemical bonds and hopping are monitored; however, the conductance originates mainly from the charge traveling through the chemical bonds in the vicinity of the zigzag edges. Our results show that in the doped systems, the device conductance decreases and the negative differential resistance characteristic becomes weak or is eliminated. Besides, the conductance in a pure zPNR system is almost independent of the ribbon width.

Observation of a discrete time crystal

NASA Astrophysics Data System (ADS)

Zhang, J.; Hess, P. W.; Kyprianidis, A.; Becker, P.; Lee, A.; Smith, J.; Pagano, G.; Potirniche, I.-D.; Potter, A. C.; Vishwanath, A.; Yao, N. Y.; Monroe, C.

2017-03-01

Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter. An example is the breaking of spatial translational symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a ‘time crystal’ was recently proposed, but was later shown to be forbidden in thermal equilibrium. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency. This new phase of matter has been dubbed a ‘discrete time crystal’. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions.

Observation of a discrete time crystal.

PubMed

Zhang, J; Hess, P W; Kyprianidis, A; Becker, P; Lee, A; Smith, J; Pagano, G; Potirniche, I-D; Potter, A C; Vishwanath, A; Yao, N Y; Monroe, C

2017-03-08

Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter. An example is the breaking of spatial translational symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a 'time crystal' was recently proposed, but was later shown to be forbidden in thermal equilibrium. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency. This new phase of matter has been dubbed a 'discrete time crystal'. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions.

Subatomic-scale force vector mapping above a Ge(001) dimer using bimodal atomic force microscopy

NASA Astrophysics Data System (ADS)

Naitoh, Yoshitaka; Turanský, Robert; Brndiar, Ján; Li, Yan Jun; Štich, Ivan; Sugawara, Yasuhiro

2017-07-01

Probing physical quantities on the nanoscale that have directionality, such as magnetic moments, electric dipoles, or the force response of a surface, is essential for characterizing functionalized materials for nanotechnological device applications. Currently, such physical quantities are usually experimentally obtained as scalars. To investigate the physical properties of a surface on the nanoscale in depth, these properties must be measured as vectors. Here we demonstrate a three-force-component detection method, based on multi-frequency atomic force microscopy on the subatomic scale and apply it to a Ge(001)-c(4 × 2) surface. We probed the surface-normal and surface-parallel force components above the surface and their direction-dependent anisotropy and expressed them as a three-dimensional force vector distribution. Access to the atomic-scale force distribution on the surface will enable better understanding of nanoscale surface morphologies, chemical composition and reactions, probing nanostructures via atomic or molecular manipulation, and provide insights into the behaviour of nano-machines on substrates.

Disintegration of a Liquid Jet

NASA Technical Reports Server (NTRS)

Haenlein, A

1932-01-01

This report presents an experimental determination of the process of disintegration and atomization in its simplest form, and the influence of the physical properties of the liquid to be atomized on the disintegration of the jet. Particular attention was paid to the investigation of the process of atomization.

Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy.

PubMed

Wang, Zechao; Tavabi, Amir H; Jin, Lei; Rusz, Ján; Tyutyunnikov, Dmitry; Jiang, Hanbo; Moritomo, Yutaka; Mayer, Joachim; Dunin-Borkowski, Rafal E; Yu, Rong; Zhu, Jing; Zhong, Xiaoyan

2018-03-01

In order to obtain a fundamental understanding of the interplay between charge, spin, orbital and lattice degrees of freedom in magnetic materials and to predict and control their physical properties 1-3 , experimental techniques are required that are capable of accessing local magnetic information with atomic-scale spatial resolution. Here, we show that a combination of electron energy-loss magnetic chiral dichroism 4 and chromatic-aberration-corrected transmission electron microscopy, which reduces the focal spread of inelastically scattered electrons by orders of magnitude when compared with the use of spherical aberration correction alone, can achieve atomic-scale imaging of magnetic circular dichroism and provide element-selective orbital and spin magnetic moments atomic plane by atomic plane. This unique capability, which we demonstrate for Sr 2 FeMoO 6 , opens the door to local atomic-level studies of spin configurations in a multitude of materials that exhibit different types of magnetic coupling, thereby contributing to a detailed understanding of the physical origins of magnetic properties of materials at the highest spatial resolution.

Assessment of current atomic scale modelling methods for the investigation of nuclear fuels under irradiation: Example of uranium dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertolus, Marjorie; Krack, Matthias; Freyss, Michel

Multiscale approaches are developed to build more physically based kinetic and mechanical mesoscale models to enhance the predictive capability of fuel performance codes and increase the efficiency of the development of the safer and more innovative nuclear materials needed in the future. Atomic scale methods, and in particular electronic structure and empirical potential methods, form the basis of this multiscale approach. It is therefore essential to know the accuracy of the results computed at this scale if we want to feed them into higher scale models. We focus here on the assessment of the description of interatomic interactions in uraniummore » dioxide using on the one hand electronic structure methods, in particular in the density functional theory (DFT) framework and on the other hand empirical potential methods. These two types of methods are complementary, the former enabling to get results from a minimal amount of input data and further insight into the electronic and magnetic properties, while the latter are irreplaceable for studies where a large number of atoms needs to be considered. We consider basic properties as well as specific ones, which are important for the description of nuclear fuel under irradiation. These are especially energies, which are the main data passed to higher scale models. We limit ourselves to uranium dioxide.« less

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…

Parity and Time-Reversal Violation in Atomic Systems

NASA Astrophysics Data System (ADS)

Roberts, B. M.; Dzuba, V. A.; Flambaum, V. V.

2015-10-01

Studying the violation of parity and time-reversal invariance in atomic systems has proven to be a very effective means of testing the electroweak theory at low energy and searching for physics beyond it. Recent developments in both atomic theory and experimental methods have led to the ability to make extremely precise theoretical calculations and experimental measurements of these effects. Such studies are complementary to direct high-energy searches, and can be performed for only a fraction of the cost. We review the recent progress in the field of parity and time-reversal violation in atoms, molecules, and nuclei, and examine the implications for physics beyond the Standard Model, with an emphasis on possible areas for development in the near future.

The scanning tunnelling microscope as an operative tool: doing physics and chemistry with single atoms and molecules.

PubMed

Rieder, Karl-Heinz; Meyer, Gerhard; Hla, Saw-Wai; Moresco, Francesca; Braun, Kai F; Morgenstern, Karina; Repp, Jascha; Foelsch, Stefan; Bartels, Ludwig

2004-06-15

The scanning tunnelling microscope, initially invented to image surfaces down to the atomic scale, has been further developed in the last few years to an operative tool, with which atoms and molecules can be manipulated at will at low substrate temperatures in different manners to create and investigate artificial structures, whose properties can be investigated employing spectroscopic dI/dV measurements. The tunnelling current can be used to selectively break chemical bonds, but also to induce chemical association. These possibilities give rise to startling new opportunities for physical and chemical experiments on the single atom and single molecule level. Here we provide a short overview on recent results obtained with these techniques.

Quantum Mechanics in Insulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aeppli, G.; Department of Physics and Astronomy, University College of London, London

Atomic physics is undergoing a large revival because of the possibility of trapping and cooling ions and atoms both for individual quantum control as well as collective quantum states, such as Bose-Einstein condensates. The present lectures start from the 'atomic' physics of isolated atoms in semiconductors and insulators and proceed to coupling them together to yield magnets undergoing quantum phase transitions as well as displaying novel quantum states with no classical analogs. The lectures are based on: G.-Y. Xu et al., Science 317, 1049-1052 (2007); G. Aeppli, P. Warburton, C. Renner, BT Technology Journal, 24, 163-169 (2006); H. M. Ronnowmore » et al., Science 308, 392-395 (2005) and N. Q. Vinh et al., PNAS 105, 10649-10653 (2008).« less

The Physical Properties of a Lavage Mixture of Pulmonary Surfactant, Perfluorodecaline, and Methylprednisolone (Perfactant Lavage)

DTIC Science & Technology

2014-05-09

release: distribution unlimited Purpose: To characterize the physical properties of a lavage mixture of pulmonary surfactant, perfluorocarbon and...methylprednisolone. Background: Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by the substitution of hydrogen atoms with fluorine...atoms. Perfluorocarbon liquids are colorless, odorless and biologically inert. They are highly dense, due to their molecular weight. Their low

Physics, History, and the German Atomic Bomb.

PubMed

Walker, Mark

2017-04-27

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

Molecular dynamics simulations through GPU video games technologies

PubMed Central

Loukatou, Styliani; Papageorgiou, Louis; Fakourelis, Paraskevas; Filntisi, Arianna; Polychronidou, Eleftheria; Bassis, Ioannis; Megalooikonomou, Vasileios; Makałowski, Wojciech; Vlachakis, Dimitrios; Kossida, Sophia

2016-01-01

Bioinformatics is the scientific field that focuses on the application of computer technology to the management of biological information. Over the years, bioinformatics applications have been used to store, process and integrate biological and genetic information, using a wide range of methodologies. One of the most de novo techniques used to understand the physical movements of atoms and molecules is molecular dynamics (MD). MD is an in silico method to simulate the physical motions of atoms and molecules under certain conditions. This has become a state strategic technique and now plays a key role in many areas of exact sciences, such as chemistry, biology, physics and medicine. Due to their complexity, MD calculations could require enormous amounts of computer memory and time and therefore their execution has been a big problem. Despite the huge computational cost, molecular dynamics have been implemented using traditional computers with a central memory unit (CPU). A graphics processing unit (GPU) computing technology was first designed with the goal to improve video games, by rapidly creating and displaying images in a frame buffer such as screens. The hybrid GPU-CPU implementation, combined with parallel computing is a novel technology to perform a wide range of calculations. GPUs have been proposed and used to accelerate many scientific computations including MD simulations. Herein, we describe the new methodologies developed initially as video games and how they are now applied in MD simulations. PMID:27525251

Spin dynamics and Kondo physics in optical tweezers

NASA Astrophysics Data System (ADS)

Lin, Yiheng; Lester, Brian J.; Brown, Mark O.; Kaufman, Adam M.; Long, Junling; Ball, Randall J.; Isaev, Leonid; Wall, Michael L.; Rey, Ana Maria; Regal, Cindy A.

2016-05-01

We propose to use optical tweezers as a toolset for direct observation of the interplay between quantum statistics, kinetic energy and interactions, and thus implement minimum instances of the Kondo lattice model in systems with few bosonic rubidium atoms. By taking advantage of strong local exchange interactions, our ability to tune the spin-dependent potential shifts between the two wells and complete control over spin and motional degrees of freedom, we design an adiabatic tunneling scheme that efficiently creates a spin-singlet state in one well starting from two initially separated atoms (one atom per tweezer) in opposite spin state. For three atoms in a double-well, two localized in the lowest vibrational mode of each tweezer and one atom in an excited delocalized state, we plan to use similar techniques and observe resonant transfer of two-atom singlet-triplet states between the wells in the regime when the exchange coupling exceeds the mobile atom hopping. Moreover, we argue that such three-atom double-tweezers could potentially be used for quantum computation by encoding logical qubits in collective spin and motional degrees of freedom. Current address: Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.

Many-body physics using cold atoms

NASA Astrophysics Data System (ADS)

Sundar, Bhuvanesh

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

Sensor Network Middleware for Cyber-Physical Systems: Opportunities and Challenges

NASA Astrophysics Data System (ADS)

Singh, G.

2015-12-01

Wireless Sensor Network middleware typically provides abstractions for common tasks such as atomicity, synchronization and communication with the intention of isolating the developers of distributed applications from lower-level details of the underlying platforms. Developing middleware to meet the performance constraints of applications is an important challenge. Although one would like to develop generic middleware services which can be used in a variety of different applications, efficiency considerations often force developers to design middleware and algorithms customized to specific operational contexts. This presentation will discuss techniques to design middleware that is customizable to suit the performance needs of specific applications. We also discuss the challenges poised in designing middleware for pervasive sensor networks and cyber-physical systems with specific focus on environmental monitoring.

Preface

NASA Astrophysics Data System (ADS)

Makabe, Toshiaki; Samukawa, Seiji

2007-06-01

Twenty-first century will be the era of the design technology on a firm basis of physics and chemistry under circumstances of a prospective high-speed computing along the line of environmentally friendly and economically saving society. The 4th International Workshop on Basic Aspects of Nonequilibrium Plasmas Interacting with Surfaces (BANPIS); Negative ions, their function & designability, and the 4th EU-Japan Joint Symposium on Plasma Processes (JSPP) were held at Hotel Highland Resort close to Mt. Fuji in Japan on January 30 - February 1, 2006. The joint conference was organized by the 21st century Center of Excellence (COE) for ;Optical & Electronic Device Technology for Access Networks; in Keio University, and co-operated by the Center for ;Atomic and Molecular Engineering,; in Open University, and by The Japan Society of Applied Physics.

Semiclassical Planetology: a progress report

NASA Astrophysics Data System (ADS)

Celebonovic, V.

1999-12-01

Work on planetary internal structure has started in Yugoslavia in the early sixties.It was initiated by P.Savic and R.Kasanin,who have jointly developed a theory of the behaviour of materials under high pressure.By its physical basis,this theory is semiclassical,because it is based on classical physics combined with some quantum mechanical results.The calculations in the theory ( both laboratory and planetological) are baed on ths idea that high pressure leads to excitation and ionisation of atoms and/or molecules which make up the specimen. In this paper we shall briefly present the main ideas of this theory,and then discuss its planetological applications. References P.Savic and V.Celebonovic: 1994,AIP Conf.Proc.,vol.309,p.53. V.Celebonovic: 1999,preprint cond-mat/9906027

Work of the Tamm-Sakharov group on the first hydrogen bomb

NASA Astrophysics Data System (ADS)

Ritus, V. I.

2014-09-01

This review is an extended version of a report delivered at a session of the Department of Physical Sciences, the Department of Energetics, Mechanical Engineering, Mechanics, and Control Processes, and the Coordination Council on Technical Sciences of the RAS devoted to the 60th anniversary of the first hydrogen bomb test. The significant physical ideas suggested by A D Sakharov and V L Ginzburg underlying our first hydrogen bomb, RDS-6s, and numerous concrete problems and difficulties that had to be solved and overcome in designing thermonuclear weapons are presented. The understanding of the country's leaders and the Atomic Project managers of the exceptional role of fundamental science in the appearance and implementation of our scientists' concrete ideas and suggestions is emphasized.

A physical description of fission product behavior fuels for advanced power reactors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaganas, G.; Rest, J.; Nuclear Engineering Division

2007-10-18

The Global Nuclear Energy Partnership (GNEP) is considering a list of reactors and nuclear fuels as part of its chartered initiative. Because many of the candidate materials have not been explored experimentally under the conditions of interest, and in order to economize on program costs, analytical support in the form of combined first principle and mechanistic modeling is highly desirable. The present work is a compilation of mechanistic models developed in order to describe the fission product behavior of irradiated nuclear fuel. The mechanistic nature of the model development allows for the possibility of describing a range of nuclear fuelsmore » under varying operating conditions. Key sources include the FASTGRASS code with an application to UO{sub 2} power reactor fuel and the Dispersion Analysis Research Tool (DART ) with an application to uranium-silicide and uranium-molybdenum research reactor fuel. Described behavior mechanisms are divided into subdivisions treating fundamental materials processes under normal operation as well as the effect of transient heating conditions on these processes. Model topics discussed include intra- and intergranular gas-atom and bubble diffusion, bubble nucleation and growth, gas-atom re-solution, fuel swelling and ?scion gas release. In addition, the effect of an evolving microstructure on these processes (e.g., irradiation-induced recrystallization) is considered. The uranium-alloy fuel, U-xPu-Zr, is investigated and behavior mechanisms are proposed for swelling in the {alpha}-, intermediate- and {gamma}-uranium zones of this fuel. The work reviews the FASTGRASS kinetic/mechanistic description of volatile ?scion products and, separately, the basis for the DART calculation of bubble behavior in amorphous fuels. Development areas and applications for physical nuclear fuel models are identified.« less

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

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.

Bimetallic Platinum-Rhodium Alloy Nanodendrites as Highly Active Electrocatalyst for the Ethanol Oxidation Reaction.

PubMed

Bai, Juan; Xiao, Xue; Xue, Yuan-Yuan; Jiang, Jia-Xing; Zeng, Jing-Hui; Li, Xi-Fei; Chen, Yu

2018-06-13

Rationally designing and manipulating composition and morphology of precious metal-based bimetallic nanostructures can markedly enhance their electrocatalytic performance, including selectivity, activity, and durability. We herein report the synthesis of bimetallic PtRh alloy nanodendrites (ANDs) with tunable composition by a facile complex-reduction synthetic method under hydrothermal conditions. The structural/morphologic features, formation mechanism, and electrocatalytic performance of PtRh ANDs are investigated thoroughly by various physical characterization and electrochemical methods. The preformed Rh crystal nuclei effectively catalyze the reduction of Pt 2+ precursor, resulting in PtRh alloy generation due to the catalytic growth and atoms interdiffusion process. The Pt atoms deposition distinctly interferes in Rh atoms deposition on Rh crystal nuclei, resulting in dendritic morphology of PtRh ANDs. For the ethanol oxidation reaction (EOR), PtRh ANDs display the chemical composition and solution pH co-dependent electrocatalytic activity. Because of the alloy effect and particular morphologic feature, Pt 1 Rh 1 ANDs with optimized composition exhibit better reactivity and stability for the EOR than commercial Pt nanocrystals electrocatalyst.

Atomic and Molecular Spectroscopic Studies of the DIII-D Neutral Beam Ion Source and Neutralizer

NASA Astrophysics Data System (ADS)

Crowley, B.; Rauch, J.; Scoville, J. T.; Sharma, S. K.; Choksi, B.

2015-11-01

The neutral beam system is interesting in that it comprises two distinct low temperature plasmas. Firstly, the ion source is typically a filament or RF driven plasma from which ions are extracted by a high voltage accelerator grid system. Secondly the neutralizer is essentially a low temperature plasma system with the beam serving as the primary ionization source and the neutralizer walls serving as conducting boundaries. Atomic spectroscopy of Doppler shifted D-alpha light emanating from the fast atoms is studied to determine the composition of the source and the divergence of the beam. Molecular spectroscopy involves measuring fine structure in electron-vibrational rotational bands. The technique has applications in low temperature plasmas and here it is used to determine gas temperature in the neutralizer. We describe the experimental set-up and the physics model used to relate the spectroscopic data to the plasma parameters and we present results of recent experiments exploring how to increase neutralization efficiency. Supported by the US DOE under DE-FC02-04ER54698.

A Novel Method to Reconstruct the Force Curve by Higher Harmonics of the First Two Flexural Modes in Frequency Modulation Atomic Force Microscope (FM-AFM).

PubMed

Zhang, Suoxin; Qian, Jianqiang; Li, Yingzi; Zhang, Yingxu; Wang, Zhenyu

2018-06-04

Atomic force microscope (AFM) is an idealized tool to measure the physical and chemical properties of the sample surfaces by reconstructing the force curve, which is of great significance to materials science, biology, and medicine science. Frequency modulation atomic force microscope (FM-AFM) collects the frequency shift as feedback thus having high force sensitivity and it accomplishes a true noncontact mode, which means great potential in biological sample detection field. However, it is a challenge to establish the relationship between the cantilever properties observed in practice and the tip-sample interaction theoretically. Moreover, there is no existing method to reconstruct the force curve in FM-AFM combining the higher harmonics and the higher flexural modes. This paper proposes a novel method that a full force curve can be reconstructed by any order higher harmonics of the first two flexural modes under any vibration amplitude in FM-AFM. Moreover, in the small amplitude regime, short range forces are reconstructed more accurately by higher harmonics analysis compared with fundamental harmonics using the Sader-Jarvis formula.

First FAMU observation of muon transfer from μp atoms to higher-Z elements

NASA Astrophysics Data System (ADS)

Mocchiutti, E.; Bonvicini, V.; Carbone, R.; Danailov, M.; Furlanetto, E.; Gadedjisso-Tossou, K. S.; Guffanti, D.; Pizzolotto, C.; Rachevski, A.; Stoychev, L.; Vallazza, E.; Zampa, G.; Niemela, J.; Ishida, K.; Adamczak, A.; Baccolo, G.; Benocci, R.; Bertoni, R.; Bonesini, M.; Chignoli, F.; Clemenza, M.; Curioni, A.; Maggi, V.; Mazza, R.; Moretti, M.; Nastasi, M.; Previtali, E.; Bakalov, D.; Danev, P.; Stoilov, M.; Baldazzi, G.; Campana, G.; D'Antone, I.; Furini, M.; Fuschino, F.; Labanti, C.; Margotti, A.; Meneghini, S.; Morgante, G.; Rignanese, L. P.; Rossi, P. L.; Zuffa, M.; Cervi, T.; De Bari, A.; Menegolli, A.; De Vecchi, C.; Nardò, R.; Rossella, M.; Tomaselli, A.; Colace, L.; De Vincenzi, M.; Iaciofano, A.; Somma, F.; Tortora, L.; Ramponi, R.; Vacchi, A.

2018-02-01

The FAMU experiment aims to accurately measure the hyperfine splitting of the ground state of the muonic hydrogen atom. A measurement of the transfer rate of muons from hydrogen to heavier gases is necessary for this purpose. In June 2014, within a preliminary experiment, a pressurized gas-target was exposed to the pulsed low-energy muon beam at the RIKEN RAL muon facility (Rutherford Appleton Laboratory, U.K.). The main goal of the test was the characterization of both the noise induced by the pulsed beam and the X-ray detectors. The apparatus, to some extent rudimental, has served admirably to this task. Technical results have been published that prove the validity of the choices made and pave the way for the next steps. This paper presents the results of physical relevance of measurements of the muon transfer rate to carbon dioxide, oxygen, and argon from non-thermalized excited μp atoms. The analysis methodology and the approach to the systematics errors are useful for the subsequent study of the transfer rate as function of the kinetic energy of the μp currently under way.

PSI for Low-Enrollment Junior-Senior Physics Courses

ERIC Educational Resources Information Center

Frahm, Charles P.; Young, Robert D.

1976-01-01

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

Universal structural parameter to quantitatively predict metallic glass properties

DOE PAGES

Ding, Jun; Cheng, Yong-Qiang; Sheng, Howard; ...

2016-12-12

Quantitatively correlating the amorphous structure in metallic glasses (MGs) with their physical properties has been a long-sought goal. Here we introduce flexibility volume' as a universal indicator, to bridge the structural state the MG is in with its properties, on both atomic and macroscopic levels. The flexibility volume combines static atomic volume with dynamics information via atomic vibrations that probe local configurational space and interaction between neighbouring atoms. We demonstrate that flexibility volume is a physically appropriate parameter that can quantitatively predict the shear modulus, which is at the heart of many key properties of MGs. Moreover, the new parametermore » correlates strongly with atomic packing topology, and also with the activation energy for thermally activated relaxation and the propensity for stress-driven shear transformations. These correlations are expected to be robust across a very wide range of MG compositions, processing conditions and length scales.« less

Investigation of the abnormal Zn diffusion phenomenon in III-V compound semiconductors induced by the surface self-diffusion of matrix atoms

NASA Astrophysics Data System (ADS)

Tang, Liangliang; Xu, Chang; Liu, Zhuming

2017-01-01

Zn diffusion in III-V compound semiconductorsare commonly processed under group V-atoms rich conditions because the vapor pressure of group V-atoms is relatively high. In this paper, we found that group V-atoms in the diffusion sources would not change the shaped of Zn profiles, while the Zn diffusion would change dramatically undergroup III-atoms rich conditions. The Zn diffusions were investigated in typical III-V semiconductors: GaAs, GaSb and InAs. We found that under group V-atoms rich or pure Zn conditions, the double-hump Zn profiles would be formed in all materials except InAs. While under group III-atoms rich conditions, single-hump Zn profiles would be formed in all materials. Detailed diffusion models were established to explain the Zn diffusion process; the surface self-diffusion of matrix atoms is the origin of the abnormal Zn diffusion phenomenon.

Linear build-up of Fano resonance spectral profiles

NASA Astrophysics Data System (ADS)

Golovinski, P. A.; Yakovets, A. V.; Astapenko, V. A.

2018-06-01

The build-up dynamics of a continuous spectrum under the action of a weak laser field on a Fano resonance with the use of the pulses with the Lorentz spectrum and ultrashort pulses in the wavelet form is investigated. A dispersion-time excitation dependence of the Fano resonances in a He atom, in an InP impurity semiconductor, in longitudinal optical LO-phonons of a shallow donor exciton in pure ZnO crystals, and in metamaterials are calculated. The numerical simulation of the dynamics has shown time-dependent formation of a Fano spectral profile in the systems of different physical natures under the action of ultrashort pulses with attosecond and femtosecond durations.

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,…

Physics Division annual review, 1 April 1975--31 March 1976. [ANL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvey, G. T.

1976-01-01

An overview is given of Physics Division activities in the following areas: the heavy-ion booster; medium-energy physics; heavy-ion physics; low-energy charged-particle physics; accelerator operations; neutron physics; theoretical nuclear physics, and atomic and molecular physics. A bibliography of publications amounts to 27 pages. (RWR)

Machine learning properties of materials and molecules with entropy-regularized kernels

NASA Astrophysics Data System (ADS)

Ceriotti, Michele; Bartók, Albert; CsáNyi, GáBor; de, Sandip

Application of machine-learning methods to physics, chemistry and materials science is gaining traction as a strategy to obtain accurate predictions of the properties of matter at a fraction of the typical cost of quantum mechanical electronic structure calculations. In this endeavor, one can leverage general-purpose frameworks for supervised-learning. It is however very important that the input data - for instance the positions of atoms in a molecule or solid - is processed into a form that reflects all the underlying physical symmetries of the problem, and that possesses the regularity properties that are required by machine-learning algorithms. Here we introduce a general strategy to build a representation of this kind. We will start from existing approaches to compare local environments (basically, groups of atoms), and combine them using techniques borrowed from optimal transport theory, discussing the relation between this idea and additive energy decompositions. We will present a few examples demonstrating the potential of this approach as a tool to predict molecular and materials' properties with an accuracy on par with state-of-the-art electronic structure methods. MARVEL NCCR (Swiss National Science Foundation) and ERC StG HBMAP (European Research Council, G.A. 677013).

Understanding the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions

NASA Astrophysics Data System (ADS)

Dahms, Rainer N.

2016-04-01

A generalized framework for multi-component liquid injections is presented to understand and predict the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions. The analysis focuses on the thermodynamic structure and the immiscibility state of representative gas-liquid interfaces. The most modern form of Helmholtz energy mixture state equation is utilized which exhibits a unique and physically consistent behavior over the entire two-phase regime of fluid densities. It is combined with generalized models for non-linear gradient theory and for liquid injections to quantify multi-component two-phase interface structures in global thermal equilibrium. Then, the Helmholtz free energy is minimized which determines the interfacial species distribution as a consequence. This minimal free energy state is demonstrated to validate the underlying assumptions of classic two-phase theory and spray atomization. However, under certain engine-relevant conditions for which corroborating experimental data are presented, this requirement for interfacial thermal equilibrium becomes unsustainable. A rigorously derived probability density function quantifies the ability of the interface to develop internal spatial temperature gradients in the presence of significant temperature differences between injected liquid and ambient gas. Then, the interface can no longer be viewed as an isolated system at minimal free energy. Instead, the interfacial dynamics become intimately connected to those of the separated homogeneous phases. Hence, the interface transitions toward a state in local equilibrium whereupon it becomes a dense-fluid mixing layer. A new conceptual view of a transitional liquid injection process emerges from a transition time scale analysis. Close to the nozzle exit, the two-phase interface still remains largely intact and more classic two-phase processes prevail as a consequence. Further downstream, however, the transition to dense-fluid mixing generally occurs before the liquid length is reached. The significance of the presented modeling expressions is established by a direct comparison to a reduced model, which utilizes widely applied approximations but fundamentally fails to capture the physical complexity discussed in this paper.

Quantum-Mechanical Combinatorial Design of Solids having Target Properties

NASA Astrophysics Data System (ADS)

Zunger, Alex

2007-03-01

(1) One of the most striking aspects of solid state physics is the diversity of structural forms in which crystals appear in Nature. Not only are there many distinct crystal-types, but combinations of two or more crystalline materials (alloys) give rise to various local geometric atomic patters. The already rich repertoire of such forms has recently been significantly enhanced by the advent of artificial crystal growth techniques (MBE, STM- atom positioning, etc.) that can create desired structural forms, such as superlattices and impurity clusters even in defiance of the rules of equilibrium thermodynamics. (2) At the same time, the fields of chemistry of nanostructures and physics of structural phase-transitions have long revealed that different atomic configurations generally lead to different physical properties even without altering the chemical makeup. While the most widely - known illustration of such ``form controls function'' rule is the dramatically different color, conductivity and hardness of the allotropical forms of pure carbon (diamond,graphite, C60), the physics of semiconductor superstructures and nanostructures is full of striking examples of how optical, magnetic and transport properties depend sensitively on atomic configuration. (3) Yet, the history of material research has generally occurred via accidental discoveries of material structures having interesting physical property (semiconductivity, ferromagnetism; superconductivity etc.). This begs the question: can this discovery process be inverted, i.e. can we first articulate a desired target physical property, then search (within a class) for the configuration that has this property? (4) The number of potentially interesting atomic configurations exhibits a combinatorial explosion, so even fast synthesis or fast computations can not survey all. (5) This talk describes the recent steps made by solid state theory + computational physics to address this ``Inverse Design'' (Franceschetti & Zunger, Nature, 402, 60 (1999) problem. I will show how Genetic Algorithms, in combination with efficient (``Order N'') solutions to the Pseudopotential Schrodinger equation allow us to investigate astronomical spaces of atomic configurations in search of the structure with a target physical property. Only a small fraction of all (˜ 10**14 in our case) configurations need to be examined. Physical properties are either calculated on-the-fly (if it's easy), or first ``Cluster-Expanded'' (if the theory is difficult). I will illustrate this Inverse Band Structure approach for (a) Design of required band-gaps in semiconductor superlattices; (b) architecture of impurity --clusters with desired optical properties (PRL 97, 046401, 2006) (c) search for configuration of magnetic ions in semiconductors that maximize the ferromagnetic Curie temperature (PRL, 97, 047202, 2006).

Radiation protection aspects of EMITEL Encyclopaedia of Medical Physics.

PubMed

Stoeva, M; Tabakov, S; Lewis, C; Tabakova, V; Thurston, J; Smith, P

2015-07-01

The Encyclopaedia of Medical Physics EMITEL was developed under the EU pilot project European Medical Imaging Technology e-Encyclopaedia for Lifelong Learning. This large reference material includes 3400 articles on 2100 pages supported by thousands of illustrations. All materials are available free at the website, www.emitel2.eu. The articles are grouped in seven categories--physics of: X-ray diagnostic radiology, nuclear medicine, radiotherapy, magnetic resonance imaging, ultrasound imaging, radiation protection and general terms. The radiation protection part of EMITEL includes 450 articles. These were organised in several sub-groups including: nuclear and atomic physics; ionizing radiation interactions and biological effects; radiation detection and measurement; dosimetric quantities and units; and general radiation protection and international bodies. EMITEL project was developed over 3 y and attracted as contributors 250+ senior specialists from 35 countries. After its successful launching, EMITEL is actively used by thousands of professionals around the world. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Physics overview of AVLIS

NASA Astrophysics Data System (ADS)

Solarz, R. W.

1985-02-01

Atomic vapor laster isotope separation (AVLIS) represents the largest-scale potential application of tunable lasers that has received serious attention. The underlying physical principles were identified and optimized, the major technology components were developed, and the integrated enrichment performance of the process was tested. The central physical processes are outlined, progress to date on the technology elements is reviewed, and scaling laws are fomulated. Two primary applications are the production of light-water reactor fuel and the conversion of fuel-grade plutonium to weapons-grade material. A variety of applications exist that all potentially use a common base of AVLIS technology. These include missions such as the enrichment of mercury isotopes to improve fluorescent lamp efficiency, the enrichment of iodine isotopes for medical isotope use, and the cleanup of strontium from defense waste for recovering strontium isotopes for radiothermal mechanical generators. The ability to radidly assess the economic and technical feasibility of each mission is derived from the general applicability of AVLIS physics and AVLIS technology.

The Use of Contact Mode Atomic Force Microscopy in Aqueous Medium for Structural Analysis of Spinach Photosynthetic Complexes

DOE PAGES

Phuthong, Witchukorn; Huang, Zubin; Wittkopp, Tyler M.; ...

2015-07-28

To investigate the dynamics of photosynthetic pigment-protein complexes in vascular plants at high resolution in an aqueous environment, membrane-protruding oxygen-evolving complexes (OECs) associated with photosystem II (PSII) on spinach ( Spinacia oleracea) grana membranes were examined using contact mode atomic force microscopy. This study represents, to our knowledge, the first use of atomic force microscopy to distinguish the putative large extrinsic loop of Photosystem II CP47 reaction center protein (CP47) from the putative oxygen-evolving enhancer proteins 1, 2, and 3 (PsbO, PsbP, and PsbQ) and large extrinsic loop of Photosystem II CP43 reaction center protein (CP43) in the PSII-OEC extrinsicmore » domains of grana membranes under conditions resulting in the disordered arrangement of PSII-OEC particles. Moreover, we observed uncharacterized membrane particles that, based on their physical characteristics and electrophoretic analysis of the polypeptides associated with the grana samples, are hypothesized to be a domain of photosystem I that protrudes from the stromal face of single thylakoid bilayers. Furthermore, our results are interpreted in the context of the results of others that were obtained using cryo-electron microscopy (and single particle analysis), negative staining and freeze-fracture electron microscopy, as well as previous atomic force microscopy studies.« less

The national ignition facility and atomic data

NASA Astrophysics Data System (ADS)

Crandall, David H.

1998-07-01

The National Ignition Facility (NIF) is under construction, capping over 25 years of development of the inertial confinement fusion concept by providing the facility to obtain fusion ignition in the laboratory for the first time. The NIF is a 192 beam glass laser to provide energy controlled in space and time so that a millimeter-scale capsule containing deuterium and tritium can be compressed to fusion conditions. Light transport, conversion of light in frequency, interaction of light with matter in solid and plasma forms, and diagnostics of extreme material conditions on small scale all use atomic data in preparing for use of the NIF. The NIF will provide opportunity to make measurements of atomic data in extreme physical environments related to fusion energy, nuclear weapon detonation, and astrophysics. The first laser beams of NIF should be operational in 2001 and the full facility completed at the end of 2003. NIF is to provide 1.8 megajoule of blue light on fusion targets and is intended to achieve fusion ignition by about the end of 2007. Today's inertial fusion development activities use atomic data to design and predict fusion capsule performance and in non-fusion applications to analyze radiation transport and radiation effects on matter. Conditions investigated involve radiation temperature of hundreds of eV, pressures up to gigabars and time scales of femptoseconds.

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…

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)…

15 CFR 255.1 - Type of fellowships.

Code of Federal Regulations, 2013 CFR

2013-01-01

... standardization and testing. (b) Practical laboratory training in various branches of physics, chemistry, and... include the usual subdivisions of physics (weights and measures, heat, optics, mechanics, atomic physics...

15 CFR 255.1 - Type of fellowships.

Code of Federal Regulations, 2011 CFR

2011-01-01

... standardization and testing. (b) Practical laboratory training in various branches of physics, chemistry, and... include the usual subdivisions of physics (weights and measures, heat, optics, mechanics, atomic physics...

15 CFR 255.1 - Type of fellowships.

Code of Federal Regulations, 2012 CFR

2012-01-01

... standardization and testing. (b) Practical laboratory training in various branches of physics, chemistry, and... include the usual subdivisions of physics (weights and measures, heat, optics, mechanics, atomic physics...

15 CFR 255.1 - Type of fellowships.

Code of Federal Regulations, 2014 CFR

2014-01-01

... standardization and testing. (b) Practical laboratory training in various branches of physics, chemistry, and... include the usual subdivisions of physics (weights and measures, heat, optics, mechanics, atomic physics...

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 CFR - Delegation of Certain Functions Under Section 104(g) of the United States-India Peaceful Atomic...

Code of Federal Regulations, 2011 CFR

2011-01-01

...) of the United States-India Peaceful Atomic Energy Cooperation Act of 2006, as Amended by Public Law... Certain Functions Under Section 104(g) of the United States-India Peaceful Atomic Energy Cooperation Act... President by section 104(g) of the United States-India Peaceful Atomic Energy Cooperation Act of 2006...

Engaging undergraduate students in hadron physics research and instrumentation

NASA Astrophysics Data System (ADS)

Horn, Tanja

2017-09-01

Nuclear physics research is fundamental to our understanding of the visible universe and at the same time intertwined with our daily life. Nuclear physics studies the origin and structure of the atomic nuclei in terms of their basic constituents, the quarks and gluons. Atoms and molecules would not exist without underlying quark-gluon interactions, which build nearly all the mass of the visible universe from an assembly of massless gluons and nearly-massless quarks. The study of hadron structure with electromagnetic probes through exclusive and semi-inclusive scattering experiments carried out at the 12 GeV Jefferson Laboratory plays an important role in this effort. In particular, planned precision measurements of pion and kaon form factors and longitudinal-transverse separated deep exclusive pion and kaon electroproduction cross sections to the highest momentum transfers achievable play an important role in understanding hadron structure and masses and provide essential constraints for 3D hadron imaging. While a growing fraction of nuclear physics research is carried out at large international laboratories, individual university research groups play critical roles in the success of that research. These include data analysis projects and the development of state-of-the-art instrumentation demanded by increasingly sophisticated experiments. These efforts are empowered by the creativity of university faculty, staff, postdocs, and provide students with unique hands-on experience. As an example, an aerogel Cherenkov detector enabling strangeness physics research in Hall C at Jefferson Lab was constructed at the Catholic University of America with the help of 16 undergraduate and high school students. The ''Conference Experience for Undergraduates'' (CEU) provides a venue for these students who have conducted research in nuclear physics. This presentation will present the experiences of one of the participants in the first years of the CEU, her current research program in hadronic physics, and her current and former students who have been participating in more recent CEU events. Supported in part by NSF Grants PHY1714133, PHY1306227 and PHY1306418.

Noise in state of the art clocks and their impact for fundamental physics

NASA Technical Reports Server (NTRS)

Maleki, L.

2001-01-01

In this paper a review of the use of advanced atomic clocks in testing the fundamental physical laws will be presented. Noise sources of clocks will be discussed, together with an outline their characterization based on current models. The paper will conclude with a discussion of recent attempts to reduce the fundamental, as well as technical noise in atomic clocks.

The Development of Open University New Generation Learning Model Using Research and Development for Atomic Physics Course PEFI4421

ERIC Educational Resources Information Center

Prayekti

2017-01-01

This research was aimed at developing printed teaching materials of Atomic Physics PEFI4421 Course using Research and Development (R & D) model; which consisted of three major set of activities. The first set consisted of seven stages, the second set consisted of one stage, and the third set consisted of seven stages. This research study was…

Essay: Samuel Abraham Goudsmit (1902 1978)

NASA Astrophysics Data System (ADS)

Bederson, Benjamin

2008-07-01

When Sam Goudsmit was 23, he and George Uhlenbeck hypothesized that the electron had spin. Sam was a well-known atomic physicist working at the University of Michigan when World War II began. During the war he first worked on radar at the MIT Radiation Lab, and then in the waning days of the war in Europe he led a mission to determine how far the Nazis had gotten in developing an atomic bomb. After chairing the Physics Department at Brookhaven, in 1950 APS named Goudsmit Managing Editor of Physical Review and Reviews of Modern Physics; in 1966 he was named Editor-in-Chief. He founded Physical Review Letters in 1958.

36 CFR 1260.28 - Who is responsible for declassifying records that contain information classified under the Atomic...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Who is responsible for declassifying records that contain information classified under the Atomic Energy Act of 1954, as amended... records that contain information classified under the Atomic Energy Act of 1954, as amended, commonly...

36 CFR 1260.28 - Who is responsible for declassifying records that contain information classified under the Atomic...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Who is responsible for declassifying records that contain information classified under the Atomic Energy Act of 1954, as amended... records that contain information classified under the Atomic Energy Act of 1954, as amended, commonly...

Progress in Development of the ITER Plasma Control System Simulation Platform

NASA Astrophysics Data System (ADS)

Walker, Michael; Humphreys, David; Sammuli, Brian; Ambrosino, Giuseppe; de Tommasi, Gianmaria; Mattei, Massimiliano; Raupp, Gerhard; Treutterer, Wolfgang; Winter, Axel

2017-10-01

We report on progress made and expected uses of the Plasma Control System Simulation Platform (PCSSP), the primary test environment for development of the ITER Plasma Control System (PCS). PCSSP will be used for verification and validation of the ITER PCS Final Design for First Plasma, to be completed in 2020. We discuss the objectives of PCSSP, its overall structure, selected features, application to existing devices, and expected evolution over the lifetime of the ITER PCS. We describe an archiving solution for simulation results, methods for incorporating physics models of the plasma and physical plant (tokamak, actuator, and diagnostic systems) into PCSSP, and defining characteristics of models suitable for a plasma control development environment such as PCSSP. Applications of PCSSP simulation models including resistive plasma equilibrium evolution are demonstrated. PCSSP development supported by ITER Organization under ITER/CTS/6000000037. Resistive evolution code developed under General Atomics' Internal funding. The views and opinions expressed herein do not necessarily reflect those of the ITER Organization.

Walter Greiner: In Memoriam

NASA Astrophysics Data System (ADS)

Zen Vasconcellos, César; Coelho, Helio T.; Hess, Peter Otto

Walter Greiner (29 October 1935 - 6 October 2016) was a German theoretical physicist. His scientific research interests include the thematic areas of atomic physics, heavy ion physics, nuclear physics, elementary particle physics (particularly quantum electrodynamics and quantum chromodynamics). He is most known in Germany for his series of books in theoretical physics, but he is also well known around the world. Greiner was born on October 29, 1935, in Neuenbau, Sonnenberg, Germany. He studied physics at the University of Frankfurt (Goethe University in Frankfurt Am Main), receiving in this institution a BSci in physics and a Master’s degree in 1960 with a thesis on plasma-reactors, and a PhD in 1961 at the University of Freiburg under Hans Marshal, with a thesis on the nuclear polarization in μ-mesic atoms. During the period of 1962 to 1964 he was assistant professor at the University of Maryland, followed by a position as research associate at the University of Freiburg, in 1964. Starting in 1965, he became a full professor at the Institute for Theoretical Physics at Goethe University until 2003. Greiner has been a visiting professor to many universities and laboratories, including Florida State University, the University of Virginia, the University of California, the University of Melbourne, Vanderbilt University, Yale University, Oak Ridge National Laboratory and Los Alamos National Laboratory. In 2003, with Wolf Singer, he was the founding Director of the Frankfurt Institute for Advanced Studies (FIAS), and gave lectures and seminars in elementary particle physics. He died on October 6, 2016 at the age of 80. Walter Greiner was an excellent teacher, researcher, friend. And he was a great supporter of the series of events known by the acronyms IWARA - International Workshop on Astronomy and Relativistic Astrophysics, STARS - Caribbean Symposium on Cosmology, Gravitation, Nuclear and Astroparticle Physics, and SMFNS - International Symposium on Strong Electromagnetic Fields and Neutron Stars. Walter Greiner left us. But his memory will remain always alive among us who have had the privilege of knowing him and enjoy his wisdom and joy of living.

Acid-Base Interactions of Polystyrene Sulfonic Acid in Amorphous Solid Dispersions Using a Combined UV/FTIR/XPS/ssNMR Study.

PubMed

Song, Yang; Zemlyanov, Dmitry; Chen, Xin; Nie, Haichen; Su, Ziyang; Fang, Ke; Yang, Xinghao; Smith, Daniel; Byrn, Stephen; Lubach, Joseph W

2016-02-01

This study investigates the potential drug-excipient interactions of polystyrene sulfonic acid (PSSA) and two weakly basic anticancer drugs, lapatinib (LB) and gefitinib (GB), in amorphous solid dispersions. Based on the strong acidity of the sulfonic acid functional group, PSSA was hypothesized to exhibit specific intermolecular acid-base interactions with both model basic drugs. Ultraviolet (UV) spectroscopy identified red shifts, which correlated well with the color change observed in lapatinib-PSSA solutions. Fourier transform infrared (FTIR) spectra suggest the protonation of the quinazoline nitrogen atom in both model compounds, which agrees well with data from the crystalline ditosylate salt of lapatinib. X-ray photoelectron spectroscopy (XPS) detected increases in binding energy of the basic nitrogen atoms in both lapatinib and gefitinib, strongly indicating protonation of these nitrogen atoms. (15)N solid-state NMR spectroscopy provided direct spectroscopic evidence for protonation of the quinazoline nitrogen atoms in both LB and GB, as well as the secondary amine nitrogen atom in LB and the tertiary amine nitrogen atom in GB. The observed chemical shifts in the LB-PSSA (15)N spectrum also agree very well with the lapatinib ditosylate salt where proton transfer is known. Additionally, the dissolution and physical stability behaviors of both amorphous solid dispersions were examined. PSSA was found to significantly improve the dissolution of LB and GB and effectively inhibit the crystallization of LB and GB under accelerated storage conditions due to the beneficial strong intermolecular acid-base interaction between the sulfonic acid groups and basic nitrogen centers.

Correlations between interacting Rydberg atoms

NASA Astrophysics Data System (ADS)

Paris-Mandoki, Asaf; Braun, Christoph; Hofferberth, Sebastian

2018-04-01

This paper is a short introduction to Rydberg physics and quantum nonlinear optics using Rydberg atoms. It has been prepared as a compliment to a series of lectures delivered during the Latin American School of Physics "Marcos Moshinsky" 2017. We provide a short introduction to the properties of individual Rydberg atoms and discuss in detail how the interaction potential between Rydberg atom pairs is calculated. We then discuss how this interaction gives rise to the Rydberg blockade mechanism. With the aid of hallmark experiments in the field applications of the blockade for creating correlated quantum systems are discussed. Our aim is to give an overview of this exciting and rapidly evolving field. The interested reader is referred to original work and more comprehensive reviews and tutorials for further details on these subjects.

Reactions of atomic oxygen with the chlorate ion and the perchlorate ion

NASA Astrophysics Data System (ADS)

Anan'ev, Vladimir; Miklin, Mikhail; Kriger, Ludmila

2014-06-01

The reactions of the chlorate ion with atomic oxygen formed under photolysis of the nitrate ion introduced to potassium chlorate crystal by co-crystallization were studied by optical and infrared absorption spectroscopy. The perchlorate ion was found to form in solids as product of addition reaction of singlet atomic oxygen, formed under dissociation of the peroxynitrite ion - the product of isomerization of the excited nitrate ion. Triplet atomic oxygen does not react with the chlorate ion. The atomic oxygen formed under photolysis of the nitrate ion introduced to potassium perchlorate crystal by co-crystallization does not react with the perchlorate ion.

EDITORIAL: Three decades of scanning tunnelling microscopy that changed the course of surface science Three decades of scanning tunnelling microscopy that changed the course of surface science

NASA Astrophysics Data System (ADS)

Ramachandra Rao, M. S.; Margaritondo, Giorgio

2011-11-01

Three decades ago, with a tiny tip of platinum, the scientific world saw the real space imaging of single atoms with unprecedented spatial resolution. This signalled the birth of one of the most versatile surface probes, based on the physics of quantum mechanical tunnelling: the scanning tunnelling microscope (STM). Invented in 1981 by Gerd Binnig and Heinrich Rohrer of IBM, Zurich, it led to their award of the 1986 Nobel Prize. Atoms, once speculated to be abstract entities used by theoreticians for mere calculations, can be seen to exist for real with the nano-eye of an STM tip that also gives real-space images of molecules and adsorbed complexes on surfaces. From a very fundamental perspective, the STM changed the course of surface science and engineering. STM also emerged as a powerful tool to study various fundamental phenomena relevant to the properties of surfaces in technological applications such as tribology, medical implants, catalysis, sensors and biology—besides elucidating the importance of local bonding geometries and defects, non-periodic structures and the co-existence of nano-scale phases. Atom-level probing, once considered a dream, has seen the light with the evolution of STM. An important off-shoot of STM was the atomic force microscope (AFM) for surface mapping of insulating samples. Then followed the development of a flurry of techniques under the general name of scanning probe microscopy (SPM). These techniques (STM, AFM, MFM, PFM etc) designed for atomic-scale-resolution imaging and spectroscopy, have led to brand new developments in surface analysis. All of these novel methods enabled researchers in recent years to image and analyse complex surfaces on microscopic and nanoscopic scales. All of them utilize a small probe for sensing the surface. The invention of AFM by Gerd Binnig, Calvin Quate and Christopher Gerber opened up new opportunities for characterization of a variety of materials, and various industrial applications could be envisaged. AFM observations of thin-film surfaces give us a picture of surface topography and morphology and any visible defects. The growing importance of ultra-thin films for magnetic recording in hard disk drive systems requires an in-depth understanding of the fundamental mechanisms occurring during growth. This special issue of Journal of Physics D: Applied Physics covers all of the different aspects of SPM that illustrate the achievements of this methodology: nanoscale imaging and mapping (Chiang, and Douillard and Charra), piezoresponse force microscopy (Soergel) and STM engineering (Okuyama and Hamada, and Huang et al). Chiang takes the reader on a journey along the STM imaging of atoms and molecules on surfaces. Jesse and Kalinin explore the band excitations that occur during the corresponding processes. Jia et al propose STM and molecular beam epitaxy as a winning experimental combination at the interface of science and technology. Douillard and Charra describe the high-resolution mapping of plasmonic modes using photoemission and scanning tunnelling microscopy. Cricenti et al demonstrate the importance of SPM in material science and biology. Wiebe et al have probed atomic scale magnetism, revealed by spin polarized scanning tunnelling microscopy. In addition, Simon et al present Fourier transform scanning tunnelling spectroscopy and the possibility to obtain constant energy maps and band dispersion using local measurements. Lackinger and Heckl give a perspective of the use of STM to study covalent intermolecular coupling reactions on surfaces. Okuyama and Hamada investigated hydrogen bond imaging and engineering with STM. Soergel describes the study of substrate-dependent self-assembled CuPc molecules using piezo force microscope (PFM). We are very grateful to the authors and reviewers for the papers in this special issue of Journal of Physics D: Applied Physics. Their contributions have provided a comprehensive picture of the evolution, status and potential of scanning probe microscopy, conveying to the readers the full excitement of this forefront domain of physics.

Suprathermal electrons in kJ-laser produced plasmas: M- shell resolved high-resolution x-ray spectroscopic study of transient matter evolution

NASA Astrophysics Data System (ADS)

Condamine, F. P.; Šmíd, M.; Renner, O.; Dozières, M.; Thais, F.; Angelo, P.; Bobin, J.-L.; Rosmej, F. B.

2016-05-01

Hot electrons are of key importance to understand many physical processes in plasma physics. They impact strongly on atomic physics as almost all radiative properties are seriously modified. X-ray spectroscopy is of particular interest due to reduced photoabsorption in dense matter. We report on a study of the copper Kα X-ray emission conducted at the ns, kJ laser facility PALS, Prague, Czech Republic. Thin copper foils have been irradiated with 1ω pulses. Two spherically bent quartz Bragg crystal spectrometers with high spectral and spatial resolution have been set up simultaneously to achieve a high level of confidence in the spectral distribution. In particular, an emission on the red wing of the Kα2 transition (λ = 1.5444 Å) could be identified with complex atomic structure calculations. We discuss possible implications for the analysis of non-equilibrium phenomena and present first atomic physics simulations.

Three-Body Recombination near a Narrow Feshbach Resonance in Li 6

NASA Astrophysics Data System (ADS)

Li, Jiaming; Liu, Ji; Luo, Le; Gao, Bo

2018-05-01

We experimentally measure and theoretically analyze the three-atom recombination rate, L3, around a narrow s -wave magnetic Feshbach resonance of Li 6 - Li 6 at 543.3 G. By examining both the magnetic field dependence and, especially, the temperature dependence of L3 over a wide range of temperatures from a few μ K to above 200 μ K , we show that three-atom recombination through a narrow resonance follows a universal behavior determined by the long-range van der Waals potential and can be described by a set of rate equations in which three-body recombination proceeds via successive pairwise interactions. We expect the underlying physical picture to be applicable not only to narrow s wave resonances, but also to resonances in nonzero partial waves, and not only at ultracold temperatures, but also at much higher temperatures.

Noncontact Viscoelastic Imaging of Living Cells Using a Long-Needle Atomic Force Microscope with Dual-Frequency Modulation

NASA Astrophysics Data System (ADS)

Guan, Dongshi; Charlaix, Elisabeth; Qi, Robert Z.; Tong, Penger

2017-10-01

Imaging of surface topography and elasticity of living cells can provide insight into the roles played by the cells' volumetric and mechanical properties and their response to external forces in regulating the essential cellular events and functions. Here, we report a unique technique of noncontact viscoelastic imaging of live cells using atomic force microscopy (AFM) with a long-needle glass probe. Because only the probe tip is placed in a liquid medium near the cell surface, the AFM cantilever in air functions well under dual-frequency modulation, retaining its high-quality resonant modes. The probe tip interacts with the cell surface through a minute hydrodynamic flow in the nanometer-thin gap region between them without physical contact. Quantitative measurements of the cell height, volume, and Young's modulus are conducted simultaneously. The experiment demonstrates that the long-needle AFM has a wide range of applications in the study of cell mechanics.

Sheet, ligament and droplet formation in swirling primary atomization

NASA Astrophysics Data System (ADS)

Shao, Changxiao; Luo, Kun; Chai, Min; Fan, Jianren

2018-04-01

We report direct numerical simulations of swirling liquid atomization to understand the physical mechanism underlying the sheet breakup of a non-turbulent liquid swirling jet which lacks in-depth investigation. The volume-of-fluid (VOF) method coupled with adapted mesh refinement (AMR) technique in GERRIS code is employed in the present simulation. The mechanisms of sheet, ligament and droplet formation are investigated. It is observed that the olive-shape sheet structure is similar to the experimental result qualitatively. The numerical results show that surface tension, pressure difference and swirling effect contribute to the contraction and extension of liquid sheet. The ligament formation is partially at the sheet rim or attributed to the extension of liquid hole. Especially, the movement of hairpin vortex exerts by an anti-radial direction force to the sheet surface and leads to the sheet thinness. In addition, droplet formation is attributed to breakup of ligament and central sheet.

Low temperature formation of higher-k cubic phase HfO{sub 2} by atomic layer deposition on GeO{sub x}/Ge structures fabricated by in-situ thermal oxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R., E-mail: zhang@mosfet.t.u-tokyo.ac.jp; Department of Information Science and Electronic Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027; Huang, P.-C.

2016-02-01

We have demonstrated a low temperature formation (300 °C) of higher-k HfO{sub 2} using atomic layer deposition (ALD) on an in-situ thermal oxidation GeO{sub x} interfacial layer. It is found that the cubic phase is dominant in the HfO{sub 2} film with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfO{sub 2} film on a 1-nm-thick GeO{sub x} form by the in-situ thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO{sub 2} can be induced by the formation of six-fold crystalline GeO{sub x} structures in the underlying GeO{sub x}more » interfacial layer.« less

Application of atomic force microscopy to microbial surfaces: from reconstituted cell surface layers to living cells.

PubMed

Dufrêne, Y F

2001-02-01

The application of atomic force microscopy (AFM) to probe the ultrastructure and physical properties of microbial cell surfaces is reviewed. The unique capabilities of AFM can be summarized as follows: imaging surface topography with (sub)nanometer lateral resolution; examining biological specimens under physiological conditions; measuring local properties and interaction forces. AFM is being used increasingly for: (i) visualizing the surface ultrastructure of microbial cell surface layers, including bacterial S-layers, purple membranes, porin OmpF crystals and fungal rodlet layers; (ii) monitoring conformational changes of individual membrane proteins; (iii) examining the morphology of bacterial biofilms, (iv) revealing the nanoscale structure of living microbial cells, including fungi, yeasts and bacteria, (v) mapping interaction forces at microbial surfaces, such as van der Waals and electrostatic forces, solvation forces, and steric/bridging forces; and (vi) probing the local mechanical properties of cell surface layers and of single cells.

Resonant tunnelling in a quantum oxide superlattice

DOE PAGES

Choi, Woo Seok; Lee, Sang A.; You, Jeong Ho; ...

2015-06-24

Resonant tunneling is a quantum mechanical process that has long been attracting both scientific and technological attention owing to its intriguing underlying physics and unique applications for high-speed electronics. The materials system exhibiting resonant tunneling, however, has been largely limited to the conventional semiconductors, partially due to their excellent crystalline quality. Here we show that a deliberately designed transition metal oxide superlattice exhibits a resonant tunneling behaviour with a clear negative differential resistance. The tunneling occurred through an atomically thin, lanthanum δ- doped SrTiO 3 layer, and the negative differential resistance was realized on top of the bi-polar resistance switchingmore » typically observed for perovskite oxide junctions. This combined process resulted in an extremely large resistance ratio (~10 5) between the high and low resistance states. Lastly, the unprecedentedly large control found in atomically thin δ-doped oxide superlattices can open a door to novel oxide-based high-frequency logic devices.« less

Physical exploration for uranium during 1951 in the Silver Reef district, Washington County, Utah

USGS Publications Warehouse

Stugard, Frederick

1953-01-01

During 1951 a joint exploration program of the most promising uraniferous areas in the Silver Reef district was made by the U.S. Geological Survey and the u.S. Atomic Energy Commission.  A U.S. Bureau of Mines drill crew, on contract to the Atomic Energy Commission, did 2,450 feet of diamond drilling under the geological supervision of the U.S. Geological Survey.  The purpose of the drilling was to delineate broadly the favorable ground for commercial development of the uranium depostis.  Ten drill holes were located around Pumpkin Point, which is the northeastern end of Buckeye Reef, to probe for extensions of small ore shootsmined on the Point in fine-grained sandstones of the Chinle formation.  Three additional holes were located around teh Tecumseh Hill to prbe for extensions of the small showings of uranium-bearing rocks of Buckeye Reef.

Formation of Multi-Layer Structures in Bi3Pb7 Intermetallic Compounds under an Ultra-High Gravitational Field

NASA Astrophysics Data System (ADS)

Mashimo, T.; Iguchi, Y.; Bagum, R.; Sano, T.; Sakata, O.; Ono, M.; Okayasu, S.

2008-02-01

Ultra-high gravitational field (Mega-gravity field) can promote sedimentation of atoms (diffusion) even in solids, and is expected to form a compositionally-graded structure and/or nonequilibrium phase in multi-component condensed matter. We had achieved sedimentation of substitutional solute atoms in miscible systems (Bi-Sb, In-Pb, etc.). In this study, a mega-gravity experiment at high temperature was performed on a thin-plate sample (0.7 mm in thickness) of the intermetallic compound Bi3Pb7. A visible four-layer structure was produced, which exhibited different microscopic structures. In the lowest-gravity region layer, Bi phase appeared. In the mid layers, a compositionally-graded structure was formed, with differences observed in the powder X-ray diffraction patterns. Such a multi-layer structure is expected to exhibit unique physical properties such as superconductivity.

Role of codeposited impurities during growth. I. Explaining distinctive experimental morphology on Cu(0 0 1)

NASA Astrophysics Data System (ADS)

Hamouda, Ajmi Bh.; Sathiyanarayanan, Rajesh; Pimpinelli, Alberto; Einstein, T. L.

2011-01-01

A unified explanation of the physics underlying all the distinctive features of the growth instabilities observed on Cu vicinals has long eluded theorists. Recently, kinetic Monte Carlo studies showed that codeposition of impurities during growth could account for the key distinctive experimental observations [Hamouda , Phys. Rev. BPLRBAQ0556-280510.1103/PhysRevB.77.245430 77, 245430 (2008)]. To identify the responsible impurity atom, we compute the nearest-neighbor binding energies (ENN) and terrace diffusion barriers (Ed) for several candidate impurity atoms on Cu(0 0 1) using DFT-based VASP. Our calculations show that codeposition (with Cu) of midtransition elements, such as Fe, Mn, and W, could—in conjunction with substantial Ehrlich-Schwoebel barriers—cause the observed instabilities; when the experimental setup is considered, W emerges to be the most likely candidate. We discuss the role of impurities in nanostructuring of surfaces.

Weyl solitons in three-dimensional optical lattices

NASA Astrophysics Data System (ADS)

Shang, Ce; Zheng, Yuanlin; Malomed, Boris A.

2018-04-01

Weyl fermions are massless chiral quasiparticles existing in materials known as Weyl semimetals. Topological surface states, associated with the unusual electronic structure in the Weyl semimetals, have been recently demonstrated in linear systems. Ultracold atomic gases, featuring laser-assisted tunneling in three-dimensional optical lattices, can be used for the emulation of Weyl semimetals, including nonlinear effects induced by the collisional nonlinearity of atomic Bose-Einstein condensates. We demonstrate that this setting gives rise to topological states in the form of Weyl solitons at the surface of the underlying optical lattice. These nonlinear modes, being exceptionally robust, bifurcate from linear states for a given quasimomentum. The Weyl solitons may be used to design an efficient control scheme for topologically protected unidirectional propagation of excitations in light-matter-interaction physics. After the recently introduced Majorana and Dirac solitons, the Weyl solitons proposed in this work constitute the third (and the last) member in this family of topological solitons.

One-dimensional quantum matter: gold-induced nanowires on semiconductor surfaces

NASA Astrophysics Data System (ADS)

Dudy, L.; Aulbach, J.; Wagner, T.; Schäfer, J.; Claessen, R.

2017-11-01

Interacting electrons confined to only one spatial dimension display a wide range of unusual many-body quantum phenomena, ranging from Peierls instabilities to the breakdown of the canonical Fermi liquid paradigm to even unusual spin phenomena. The underlying physics is not only of tremendous fundamental interest, but may also have bearing on device functionality in future micro- and nanoelectronics with lateral extensions reaching the atomic limit. Metallic adatoms deposited on semiconductor surfaces may form self-assembled atomic nanowires, thus representing highly interesting and well-controlled solid-state realizations of such 1D quantum systems. Here we review experimental and theoretical investigations on a few selected prototypical nanowire surface systems, specifically Ge(0 0 1)-Au and Si(hhk)-Au, and the search for 1D quantum states in them. We summarize the current state of research and identify open questions and issues.

Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

PubMed Central

Bittencourt, Carla; Van Tendeloo, Gustaaf

2015-01-01

Summary A major revolution for electron microscopy in the past decade is the introduction of aberration correction, which enables one to increase both the spatial resolution and the energy resolution to the optical limit. Aberration correction has contributed significantly to the imaging at low operating voltages. This is crucial for carbon-based nanomaterials which are sensitive to electron irradiation. The research of carbon nanomaterials and nanohybrids, in particular the fundamental understanding of defects and interfaces, can now be carried out in unprecedented detail by aberration-corrected transmission electron microscopy (AC-TEM). This review discusses new possibilities and limits of AC-TEM at low voltage, including the structural imaging at atomic resolution, in three dimensions and spectroscopic investigation of chemistry and bonding. In situ TEM of carbon-based nanomaterials is discussed and illustrated through recent reports with particular emphasis on the underlying physics of interactions between electrons and carbon atoms. PMID:26425406

Physics with Cold Molecules Using Buffer Gas Cooling: Precision Measurement, Collisions, and Laser Cooling

NASA Astrophysics Data System (ADS)

Hutzler, Nicholas R.; Doyle, John M.

2014-06-01

Cryogenic buffer gas cooled beams and cells can be used to study many species, from atoms and polar molecules to biomolecules. We report on recent applications of this technique to improve the limit on the electron electric dipole moment [1], load polar molecules into a magnetic trap through optical pumping [2], perform chirally sensitive microwave spectroscopy on polyatomic molecules [3], progress towards magneto-optical trapping of polar molecules [4], and studies of atom-molecule sticking [5]. [1] The ACME Collaboration: J. Baron et al., Science 343, p. 269 (2014) [2] B. Hemmerling et al., arXiv:1310.2669, to appear in Phys. Rev. Lett. [3] D. Patterson, M. Schnell, & J. M. Doyle, Nature 497, p. 475 (2013) [4] H. Lu et al., arXiv:1310.3239, to appear in New. J. Phys. [5] J. Piskorski et al., under preparation

Some physics from 550 BC to AD 1948.

PubMed

Ganz, Jeremy C

2014-01-01

This chapter outlines terminology and its origins. It traces the development of physics ideas from Thales of Miletus, via Isaac Newton, to the nuclear physics investigations at the beginning of the twentieth century. It also outlines the evolving technology required to make the discoveries that would form the basis of radiosurgery. Up to the 1920s, all experiments on atomic structure and radioactivity had involved the use of vacuum tubes and naturally occurring radioactive substances. There was a need to make useable subatomic particles to obtain better understanding of the interior structure of atoms. Because of this, machines that could make atoms move at high speed were invented, known as particle accelerators. A new era had dawned. There is a brief mention of the effect of radiation on living tissue and of the units used to measure it.

10 CFR 8.4 - Interpretation by the General Counsel: AEC jurisdiction over nuclear facilities and materials...

Code of Federal Regulations, 2012 CFR

2012-01-01

... over nuclear facilities and materials under the Atomic Energy Act. 8.4 Section 8.4 Energy NUCLEAR... nuclear facilities and materials under the Atomic Energy Act. (a) By virtue of the Atomic Energy Act of... Atomic Energy Act of 1954 sets out a pattern for licensing and regulation of certain nuclear materials...

10 CFR 8.4 - Interpretation by the General Counsel: AEC jurisdiction over nuclear facilities and materials...

Code of Federal Regulations, 2010 CFR

2010-01-01

... over nuclear facilities and materials under the Atomic Energy Act. 8.4 Section 8.4 Energy NUCLEAR... nuclear facilities and materials under the Atomic Energy Act. (a) By virtue of the Atomic Energy Act of... Atomic Energy Act of 1954 sets out a pattern for licensing and regulation of certain nuclear materials...

10 CFR 8.4 - Interpretation by the General Counsel: AEC jurisdiction over nuclear facilities and materials...

Code of Federal Regulations, 2011 CFR

2011-01-01

... over nuclear facilities and materials under the Atomic Energy Act. 8.4 Section 8.4 Energy NUCLEAR... nuclear facilities and materials under the Atomic Energy Act. (a) By virtue of the Atomic Energy Act of... Atomic Energy Act of 1954 sets out a pattern for licensing and regulation of certain nuclear materials...

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.

The quantization of the atom in three acts

NASA Astrophysics Data System (ADS)

Ridgen, J. S.

2001-01-01

The challenge that faced physicists soon after the discovery of the quantum in 1900 was to determine the structure of the atom. Success came through the application of quantum ideas to this challenge. The focus of these efforts was the hydrogen atom. Three very different approaches led to the successful explanation of the Balmer series of hydrogen and, in the process, the foundation for atomic and molecular physics was established.

Physics Division progress report for period ending June 30, 1981

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-11-01

Progress is reported in detail in the following areas: Holifield Heavy-Ion Research Facility, nuclear physics, the UNISOR program, neutron physics, theoretical physics, the Nuclear Data Project, atomic and plasma physics, and high energy physics. Publications are listed. Separate abstracts were prepared for 34 papers. (WHK)

Physics Teachers' Views on Their Initial Teacher Education

ERIC Educational Resources Information Center

Buabeng, Isaac; Conner, Lindsey; Winter, David

2016-01-01

This paper explores New Zealand (NZ) physics teachers' and physics educators' views about Initial Teacher Education (ITE). Perspectives of physics teachers nationally indicated that in general, teachers considered themselves not well-prepared in some content areas including electronics, modern physics, and atomic and nuclear physics. This may be…

Quantum Simulation

NASA Astrophysics Data System (ADS)

Orzel, Chad

2017-06-01

One of the most active areas in atomic, molecular and optical physics is the use of ultracold atomic gases in optical lattices to simulate the behaviour of electrons in condensed matter systems. The larger mass, longer length scale, and tuneable interactions in these systems allow the dynamics of atoms moving in these systems to be followed in real time, and resonant light scattering by the atoms allows this motion to be probed on a microscopic scale using site-resolved imaging. This book reviews the physics of Hubbard-type models for both bosons and fermions in an optical lattice, which give rise to a rich variety of insulating and conducting phases depending on the lattice properties and interparticle interactions. It also discusses the effect of disorder on the transport of atoms in these models, and the recently discovered phenomenon of many-body localization. It presents several examples of experiments using both density and momentum imaging and quantum gas microscopy to study the motion of atoms in optical lattices. These illustrate the power and flexibility of ultracold-lattice analogues for exploring exotic states of matter at an unprecedented level of precision.

10 CFR Appendix A to Part 605 - The Energy Research Program Office Descriptions

Code of Federal Regulations, 2010 CFR

2010-01-01

... inorganic chemistry; chemical physics; atomic physics; photochemistry; radiation chemistry; thermodynamics... is comprised of the subfields metallurgy, ceramics, solid state physics, materials chemistry, and... listed below. (a) Applied Plasma Physics (APP) This Division seeks to develop that body of physics...

75 FR 23563 - Delegation of Certain Functions Under Section 104(g) of the United States-India Peaceful Atomic...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-04

... Certain Functions Under Section 104(g) of the United States-India Peaceful Atomic Energy Cooperation Act... President by section 104(g) of the United States-India Peaceful Atomic Energy Cooperation Act of 2006...

REU in Physics at Kansas State University--- an Evolving Program

NASA Astrophysics Data System (ADS)

Corwin, Kristan; Glymour, Bruce; Lara, Amy; Weaver, Larry; Zollman, Dean

2009-03-01

The REU site in the Physics Department at Kansas State University, funded by NSF for 13 years between 1992 and 2007, originally focused on atomic collision physics. Now the theme has broadened to include laser-matter interactions on atomic and nanoscales, and an ethics component is incorporated. Students study how atoms and molecules interact with ultra-fast optical and x-ray pulses, reveal the structure of nanoparticle crystallization and gel formation with scattered laser light, and develop computer codes for atomic interactions in Bose-Einstein condensates and nanoparticle self-assembly from lattices to gels; some have traveled to Japan for neutrino experiments. The students we select come primarily from smaller colleges and universities in the Midwest where research opportunities are limited. Prof. Weaver, who has served as PI since 1992, facilitates their transition from a teaching to research environment through lectures and individual interactions. Our program is in a period of transition. While Prof. Weaver continues to be the ``impedance match'' between students and mentors, other leadership roles are gradually being assumed by a team of faculty members who strive to preserve the intimacy and excellence of the program.

Many-body interferometry of magnetic polaron dynamics

NASA Astrophysics Data System (ADS)

Ashida, Yuto; Schmidt, Richard; Tarruell, Leticia; Demler, Eugene

2018-02-01

The physics of quantum impurities coupled to a many-body environment is among the most important paradigms of condensed-matter physics. In particular, the formation of polarons, quasiparticles dressed by the polarization cloud, is key to the understanding of transport, optical response, and induced interactions in a variety of materials. Despite recent remarkable developments in ultracold atoms and solid-state materials, the direct measurement of their ultimate building block, the polaron cloud, has remained a fundamental challenge. We propose and analyze a platform to probe time-resolved dynamics of polaron-cloud formation with an interferometric protocol. We consider an impurity atom immersed in a two-component Bose-Einstein condensate where the impurity generates spin-wave excitations that can be directly measured by the Ramsey interference of surrounding atoms. The dressing by spin waves leads to the formation of magnetic polarons and reveals a unique interplay between few- and many-body physics that is signified by single- and multi-frequency oscillatory dynamics corresponding to the formation of many-body bound states. Finally, we discuss concrete experimental implementations in ultracold atoms.

Stability investigation of a high number density Pt1/Fe2O3 single-atom catalyst under different gas environments by HAADF-STEM

NASA Astrophysics Data System (ADS)

Duan, Sibin; Wang, Rongming; Liu, Jingyue

2018-05-01

Catalysis by supported single metal atoms has demonstrated tremendous potential for practical applications due to their unique catalytic properties. Unless they are strongly anchored to the support surfaces, supported single atoms, however, are thermodynamically unstable, which poses a major obstacle for broad applications of single-atom catalysts (SACs). In order to develop strategies to improve the stability of SACs, we need to understand the intrinsic nature of the sintering processes of supported single metal atoms, especially under various gas environments that are relevant to important catalytic reactions. We report on the synthesis of high number density Pt1/Fe2O3 SACs using a facial strong adsorption method and the study of the mobility of these supported Pt single atoms at 250 °C under various gas environments that are relevant to CO oxidation, water–gas shift, and hydrogenation reactions. Under the oxidative gas environment, Fe2O3 supported Pt single atoms are stable even at high temperatures. The presence of either CO or H2 molecules in the gas environment, however, facilitates the movement of the Pt atoms. The strong interaction between CO and Pt weakens the binding between the Pt atoms and the support, facilitating the movement of the Pt single atoms. The dissociation of H2 molecules on the Pt atoms and their subsequent interaction with the oxygen species of the support surfaces dislodge the surface oxygen anchored Pt atoms, resulting in the formation of Pt clusters. The addition of H2O molecules to the CO or H2 significantly accelerates the sintering of the Fe2O3 supported Pt single atoms. An anchoring-site determined sintering mechanism is further proposed, which is related to the metal–support interaction.

Stability investigation of a high number density Pt1/Fe2O3 single-atom catalyst under different gas environments by HAADF-STEM.

PubMed

Duan, Sibin; Wang, Rongming; Liu, Jingyue

2018-05-18

Catalysis by supported single metal atoms has demonstrated tremendous potential for practical applications due to their unique catalytic properties. Unless they are strongly anchored to the support surfaces, supported single atoms, however, are thermodynamically unstable, which poses a major obstacle for broad applications of single-atom catalysts (SACs). In order to develop strategies to improve the stability of SACs, we need to understand the intrinsic nature of the sintering processes of supported single metal atoms, especially under various gas environments that are relevant to important catalytic reactions. We report on the synthesis of high number density Pt 1 /Fe 2 O 3 SACs using a facial strong adsorption method and the study of the mobility of these supported Pt single atoms at 250 °C under various gas environments that are relevant to CO oxidation, water-gas shift, and hydrogenation reactions. Under the oxidative gas environment, Fe 2 O 3 supported Pt single atoms are stable even at high temperatures. The presence of either CO or H 2 molecules in the gas environment, however, facilitates the movement of the Pt atoms. The strong interaction between CO and Pt weakens the binding between the Pt atoms and the support, facilitating the movement of the Pt single atoms. The dissociation of H 2 molecules on the Pt atoms and their subsequent interaction with the oxygen species of the support surfaces dislodge the surface oxygen anchored Pt atoms, resulting in the formation of Pt clusters. The addition of H 2 O molecules to the CO or H 2 significantly accelerates the sintering of the Fe 2 O 3 supported Pt single atoms. An anchoring-site determined sintering mechanism is further proposed, which is related to the metal-support interaction.

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.

Condensed matter physics of planets - Puzzles, progress and predictions

NASA Technical Reports Server (NTRS)

Stevenson, D. J.

1984-01-01

Attention is given to some of the major unresolved issues concerned with the physics of planetary interiors. The important advances in observations, and experimental and theoretical investigations are briefly reviewed, and some areas for further study are identified, including: the characteristics of atomic and electronic degrees of freedom at the high pressures and temperatures typical of a condensed planetary core; the behavior of water at megabar pressures; and the nature of the core-alloy in the earth and in the core mantle phase boundary. Consideration is also given to the behavior of carbon at high pressures and temperatures in the presence of oxygen and hydrogen; the behavior of the volatile ice assemblage in Titan at pressures of 2-40 kbar; and the electrical conductivities of matter under planetary core conditions.

Atomic physics constraints on the X boson

NASA Astrophysics Data System (ADS)

Jentschura, Ulrich D.; Nándori, István

2018-04-01

Recently, a peak in the light fermion pair spectrum at invariant q2≈(16.7MeV ) 2 has been observed in the bombardment of 7Li by protons. This peak has been interpreted in terms of a protophobic interaction of fermions with a gauge boson (X boson) of invariant mass ≈16.7 MeV which couples mainly to neutrons. High-precision atomic physics experiments aimed at observing the protophobic interaction need to separate the X boson effect from the nuclear-size effect, which is a problem because of the short range of the interaction (11.8 fm), which is commensurate with a "nuclear halo." Here we analyze the X boson in terms of its consequences for both electronic atoms as well as muonic hydrogen and deuterium. We find that the most promising atomic systems where the X boson has an appreciable effect, distinguishable from a finite-nuclear-size effect, are muonic atoms of low and intermediate nuclear charge numbers.

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

Droplet Breakup Mechanisms in Air-blast Atomizers

NASA Astrophysics Data System (ADS)

Aliabadi, Amir Abbas; Taghavi, Seyed Mohammad; Lim, Kelly

2011-11-01

Atomization processes are encountered in many natural and man-made phenomena. Examples are pollen release by plants, human cough or sneeze, engine fuel injectors, spray paint and many more. The physics governing the atomization of liquids is important in understanding and utilizing atomization processes in both natural and industrial processes. We have observed the governing physics of droplet breakup in an air-blast water atomizer using a high magnification, high speed, and high resolution LASER imaging technique. The droplet breakup mechanisms are investigated in three major categories. First, the liquid drops are flattened to form an oblate ellipsoid (lenticular deformation). Subsequent deformation depends on the magnitude of the internal forces relative to external forces. The ellipsoid is converted into a torus that becomes stretched and disintegrates into smaller drops. Second, the drops become elongated to form a long cylindrical thread or ligament that break up into smaller drops (Cigar-shaped deformation). Third, local deformation on the drop surface creates bulges and protuberances that eventually detach themselves from the parent drop to form smaller drops.

Super-Coulombic atom-atom interactions in hyperbolic media

NASA Astrophysics Data System (ADS)

Cortes, Cristian L.; Jacob, Zubin

2017-01-01

Dipole-dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon-polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.

Electrostatic atomization--Experiment, theory and industrial applications

NASA Astrophysics Data System (ADS)

Okuda, H.; Kelly, Arnold J.

1996-05-01

Experimental and theoretical research has been initiated at the Princeton Plasma Physics Laboratory on the electrostatic atomization process in collaboration with Charged Injection Corporation. The goal of this collaboration is to set up a comprehensive research and development program on the electrostatic atomization at the Princeton Plasma Physics Laboratory so that both institutions can benefit from the collaboration. Experimental, theoretical and numerical simulation approaches are used for this purpose. An experiment consisting of a capillary sprayer combined with a quadrupole mass filter and a charge detector was installed at the Electrostatic Atomization Laboratory to study fundamental properties of the charged droplets such as the distribution of charges with respect to the droplet radius. In addition, a numerical simulation model is used to study interaction of beam electrons with atmospheric pressure water vapor, supporting an effort to develop an electrostatic water mist fire-fighting nozzle.

From Artificial Atoms to Nanocrystal Molecules: Preparation and Properties of More Complex Nanostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Charina L; Alivisatos, A Paul

2009-10-20

Quantum dots, which have found widespread use in fields such as biomedicine, photovoltaics, and electronics, are often called artificial atoms due to their size-dependent physical properties. Here this analogy is extended to consider artificial nanocrystal molecules, formed from well-defined groupings of plasmonically or electronically coupled single nanocrystals. Just as a hydrogen molecule has properties distinct from two uncoupled hydrogen atoms, a key feature of nanocrystal molecules is that they exhibit properties altered from those of the component nanoparticles due to coupling. The nature of the coupling between nanocrystal atoms and its response to vibrations and deformations of the nanocrystal moleculemore » bonds are of particular interest. We discuss synthetic approaches, predicted and observed physical properties, and prospects and challenges toward this new class of materials.« less

PREFACE Preface

NASA Astrophysics Data System (ADS)

Bachor, Hans; Drummond, Peter; Hannaford, Peter

2011-01-01

The 22nd International Conference on Atomic Physics (ICAP 2010) was held from 25 to 30 July, 2010 in Cairns, Tropical North Queensland, Australia. This conference followed on from the series of highly successful biennial ICAP conferences held in Storrs, Innsbruck, Rio, Cambridge MA, Florence, Windsor, Amsterdam, Boulder, Munich, Ann Arbor, Paris, Tokyo, Seattle, Göteborg, Cambridge MA, Riga, Berkeley, Heidelberg, Boulder, Oxford and New York. ICAP 2010 was attended by 630 participants from 37 countries. The conference presented an outstanding program of papers covering the most recent advances in atomic physics, including atomic tests of fundamental physics and basic symmetries; precision measurements, including atomic clocks, atom interferometers and fundamental constants; ultracold gases and Bose-Einstein condensates; ultracold Fermi gases; ultracold molecules; quantum simulators with atoms and ions; few-body systems; ultrafast phenomena and free electron lasers; quantum information with atoms and ions; quantum optics and cavity QED with atoms; and hybrid and optomechanical systems. The papers in this Proceedings represent a collection of the invited talks. The conference program consisted of 48 invited talks presented in plenary sessions, including 10 'hot topic' talks highlighting the most recent advances in the field, and about 490 poster papers presented in three afternoon sessions. The program included talks by Nobel Laureates Claude Cohen-Tannoudji, Wolfgang Ketterle and Bill Phillips, a memorium talk commemorating the scientific life of Vladilen Letokhov, and an evening lecture by Alain Aspect on 'Wave particle duality for a single photon: quantum weirdness brought to light'. The conference was preceded by a two-day workshop in Cairns on Variation of Fundamental Constants and Violation of Fundamental Symmetries P, T(EDM), CPT, Lorentz Invariance, organised by the University of New South Wales; and three-day Student Workshop at Cape Tribulation, organized by the Australian Research Council Centre of Excellence for Quantum-Atom Optics (ACQAO). A website with full details of the conference program, abstracts and other information can be found at: http://www.swin.edu.au/icap2010. We would like to thank the participants, especially those who contributed talks, posters and manuscripts, for making ICAP2010 such an exciting and memorable conference. We thank the Program Committee for putting together an outstanding program and the ICAP International Advisory Committee for their expert advice and suggestions. We gratefully acknowledge the financial support of our sponsors: the Australian National University, the Australian Research Council Centre of Excellence for Quantum-Atom Optics, Griffith University, the Ian Potter Foundation, the International Union of Pure and Applied Physics, the National Institute of Standards and Technology, Swinburne University of Technology, and contributors to the trade exhibition: Coherent, Coherent Scientific, the Institute of Physics Publishing, Lastek, NewSpec, Nufern, Oxford University Press, Spectra-Physics, Springer, Toptica Photonics and Warsash Scientific. Finally, we thank our Conference Secretariat, Maria Lamari, and the Local Organising Committee for their tireless and expert efforts in the organisation of ICAP2010, and the staff of the Cairns Convention Centre, whose friendly and efficient service contributed much to the success of the conference. The next ICAP conference is planned to be held in Palaiseau, France from 23 to 27 July 2012 (http://www.ifraf.org/icap2012). Hans BachorPeter DrummondPeter HannafordEditors

Visualization of the Invisible: The Qubit as Key to Quantum Physics

NASA Astrophysics Data System (ADS)

Dür, Wolfgang; Heusler, Stefan

2014-11-01

Quantum mechanics is one of the pillars of modern physics, however rather difficult to teach at the introductory level due to the conceptual difficulties and the required advanced mathematics. Nevertheless, attempts to identify relevant features of quantum mechanics and to put forward concepts of how to teach it have been proposed.1-8 Here we present an approach to quantum physics based on the simplest quantum mechanical system—the quantum bit (qubit).1 Like its classical counterpart—the bit—a qubit corresponds to a two-level system, i.e., some system with a physical property that can admit two possible values. While typically a physical system has more than just one property or the property can admit more than just two values, in many situations most degrees of freedom can be considered to be fixed or frozen. Hence a variety of systems can be effectively described as a qubit. For instance, one may consider the spin of an electron or atom, with spin up and spin down as two possible values, and where other properties of the particle such as its mass or its position are fixed. Further examples include the polarization degree of freedom of a photon (horizontal and vertical polarization), two electronic degrees of freedom (i.e., two energy levels) of an atom, or the position of an atom in a double well potential (atom in left or right well). In all cases, only two states are relevant to describe the system.

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.

Preparation of Greenberger-Horne-Zeilinger Entangled States in the Atom-Cavity Systems

NASA Astrophysics Data System (ADS)

Xu, Nan

2018-02-01

We present a new simple scheme for the preparation of Greenberger-Horne-Zeilinger maximally entangled states of two two-level atoms. The distinct feature of the effective Hamiltonian is that there is no energy exchange between the atoms and the cavity.. Thus the scheme is insensitive to the effect of cavity field and the atom radiation.This protocol may be realizable in the realm of current physical experiment.

Interacting Dark Resonances with Plasmonic Meta-Molecules

DTIC Science & Technology

2014-09-17

different K-subsystems, as seen in Fig. 1(b). Within the transparency window, of the K-configuration atomic electromagnetic induced transparency ( EIT ...exhibits EIT -type phenomena as seen by a reduction in absorbance at x 264 THz. The basic physical mechanism behind this EIT -type phenomena can be...radiative plasmonic atom.5 However, in the presence of a second dark plasmonic atom, the EIT -type transparency at FIG. 1. (a) Atomic four-level system

Computer Simulations: A Tool to Predict Experimental Parameters with Cold Atoms

DTIC Science & Technology

2013-04-01

Department of the Army position unless so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an...specifically designed to work with cold atom systems and atom chips, and is already able to compute their key properties. We simulate our experimental...also allows one to choose different physics and define the interdependencies between them. It is not specifically designed for cold atom systems or

Atomic structure and pressure-induced phase transformations in a phase-change alloy

NASA Astrophysics Data System (ADS)

Xu, Ming

Phase-change materials exist in at least two phases under the ambient condition. One is the amorphous state and another is crystalline phase. These two phases have vastly different physical properties, such as electrical conductivity, optical reflectivity, mass density, thermal conductivity, etc. The distinct physical properties and the fast transformation between amorphous and crystalline phases render these materials the ability to store information. For example, the DVD and the Blue-ray discs take advantage of the optical reflectivity contrast, and the newly developed solid-state memories make use of the large conductivity difference. In addition, both the amorphous and crystalline phases in phase-change memories (PCMs) are very stable at room temperature, and they are easy to be scaled up in the production of devices with large storage density. All these features make phase-change materials the ideal candidates for the next-generation memories. Despite of the fast development of these new memory materials in industry, many fundamental physics problems underlying these interesting materials are still not fully resolved. This thesis is aiming at solving some of the key issues in phase-change materials. Most of phase-change materials are composed of Ge-Sb-Te constituents. Among all these Ge-Sb-Te based materials, Ge2Sb2Te5 (GST) has the best performance and has been frequently studied as a prototypical phase-change material. The first and foremost issue is the structure of the two functioning phases. In this thesis, we investigate the unique atomic structure and bonding nature of amorphous GST (a-GST) and crystalline GST ( c-GST), using ab initio tools and X-ray diffraction (XRD) methods. Their local structures and bonding scenarios are then analyzed using electronic structure calculations. In order to gain insight into the fast phase transformation mechanism, we also carried out a series of high-pressure experiments on GST. Several new polymorphs and their transformations have been revealed under high pressure via in situ XRD and in situ electrical resistivity measurements. The mechanisms of the structural and property changes have been uncovered via ab initio molecular dynamics simulations.

Spatial Dependent Spontaneous Emission of an Atom in a Semi-Infinite Waveguide of Rectangular Cross Section

NASA Astrophysics Data System (ADS)

Song, Hai-Xi; Sun, Xiao-Qi; Lu, Jing; Zhou, Lan

2018-01-01

We study a quantum electrodynamics (QED) system made of a two-level atom and a semi-infinite rectangular waveguide, which behaves as a perfect mirror in one end. The spatial dependence of the atomic spontaneous emission has been included in the coupling strength relevant to the eigenmodes of the waveguide. The role of retardation is studied for the atomic transition frequency far away from the cutoff frequencies. The atom-mirror distance introduces different phases and retardation times into the dynamics of the atom interacting resonantly with the corresponding transverse modes. It is found that the upper state population decreases from its initial as long as the atom-mirror distance does not vanish, and is lowered and lowered when more and more transverse modes are resonant with the atom. The atomic spontaneous emission can be either suppressed or enhanced by adjusting the atomic location for short retardation time. There are partial revivals and collapses due to the photon reabsorbed and re-emitted by the atom for long retardation time. Supported by National Natural Science Foundation of China under Grant Nos. 11374095, 11422540, 11434011, and 11575058, National Fundamental Research Program of China (the 973 Program) under Grant No. 2012CB922103, and Hunan Provincial Natural Science Foundation of China under Grant No. 11JJ7001

Astrochemistry at the Cryogenic Storage Ring

NASA Astrophysics Data System (ADS)

Kreckel, Holger; Becker, Arno; Blaum, Klaus; Breitenfeldt, Christian; George, Sebastian; Göck, Jürgen; Grieser, Manfred; Grussie, Florian; Guerin, Elisabeth; Heber, Oded; Karthein, Jonas; Krantz, Claude; Meyer, Christian; Mishra, Preeti; Novotny, Oldrich; O'Connor, Aodh; Saurabh, Sunny; Schippers, Stefan; Spruck, Kaija; Kumar, S. Sunil; Urbain, Xavier; Vogel, Stephen; von Hahn, Robert; Wilhelm, Patrick; Wolf, Andreas; Zajfman, Daniel

2017-01-01

Almost 200 different molecular species have been identified in space, and this number continues to grow steadily. This surprising molecular diversity bears witness to an active reaction network, in which molecular ions are the main drivers of chemistry in the gas phase. To study these reactions under controlled conditions in the laboratory is a major experimental challenge. The new Cryogenic Storage Ring (CSR) that has recently been commissioned at the Max Planck Institute for Nuclear Physics in Heidelberg will serve as an ideal testbed to study cold molecular ions in the gas phase. With residual gas densities of <140 cm-3 and temperatures below 10K, the CSR will allow for merged beams collision studies involving molecular ions, neutral atoms, free electrons and photons under true interstellar conditions.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harilal, Sivanandan S.; Brumfield, Brian E.; LaHaye, Nicole L.

2018-04-20

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

DOE PAGES

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; ...

2018-04-20

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Lastly, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Lastly, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Optical spectroscopy of laser-produced plasmas for standoff isotopic analysis

DOE PAGES

Harilal, S. S.; Brumfield, B. E.; LaHaye, N. L.; ...

2018-06-01

This review article covers the present status of isotope detection through emission, absorption, and fluorescence spectroscopy of atoms and molecules in a laser-produced plasma formed from a solid sample. A description of the physics behind isotope shifts in atoms and molecules is presented, followed by the physics behind solid sampling of laser ablation plumes, optical methods for isotope measurements, the suitable physical conditions of laser-produced plasma plumes for isotopic analysis, and the current status. Finally, concluding remarks will be made on the existing gaps between previous works in the literature and suggestions for future work.

Underlying role of mechanical rigidity and topological constraints in physical sputtering and reactive ion etching of amorphous materials

NASA Astrophysics Data System (ADS)

Bhattarai, Gyanendra; Dhungana, Shailesh; Nordell, Bradley J.; Caruso, Anthony N.; Paquette, Michelle M.; Lanford, William A.; King, Sean W.

2018-05-01

Analytical expressions describing ion-induced sputter or etch processes generally relate the sputter yield to the surface atomic binding energy (Usb) for the target material. While straightforward to measure for the crystalline elemental solids, Usb is more complicated to establish for amorphous and multielement materials due to composition-driven variations and incongruent sublimation. In this regard, we show that for amorphous multielement materials, the ion-driven yield can instead be better understood via a consideration of mechanical rigidity and network topology. We first demonstrate a direct relationship between Usb, bulk modulus, and ion sputter yield for the elements, and then subsequently prove our hypothesis for amorphous multielement compounds by demonstrating that the same relationships exist between the reactive ion etch (RIE) rate and nanoindentation Young's modulus for a series of a -Si Nx :H and a -Si OxCy :H thin films. The impact of network topology is further revealed via application of the Phillips-Thorpe theory of topological constraints, which directly relates the Young's modulus to the mean atomic coordination () for an amorphous solid. The combined analysis allows the trends and plateaus in the RIE rate to be ultimately reinterpreted in terms of the atomic structure of the target material through a consideration of . These findings establish the important underlying role of mechanical rigidity and network topology in ion-solid interactions and provide additional considerations for the design and optimization of radiation-hard materials in nuclear and outer space environments.

Physics division progress report for period ending September 30 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livingston, A.B.

1992-03-01

This report discusses research being conducted at Oak Ridge National Laboratory in physics. The areas covered are: Holifield Heavy Ion Research Facility; low/medium energy nuclear physics; high energy experimental physics; the Unisor program; experimental atomic physics; laser and electro-optics lab; theoretical physics; compilations and evaluations; and radioactive ion beam development. (LSP)

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

PubMed Central

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

2014-01-01

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

Atomic physics research with second and third generation synchrotron light sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, B.M.

1990-10-01

This contribution to these proceedings is intended to provide an introduction and overview for other contributions on atomic (and related) physics research at existing and planned synchrotron light sources. The emphasis will be on research accomplishments and future opportunities, but a comparison will be given of operating characteristics for first, second, and third generation machines. First generation light sources were built to do research with the primary electron and positron beams, rather than with the synchrotron radiation itself. Second generation machines were specifically designed to be dedicated synchrotron-radiation facilities, with an emphasis on the use of bending-magnet radiation. The newmore » third generation light sources are being designed to optimize radiation from insertion devices, such as undulators and wigglers. Each generation of synchrotron light source offers useful capabilities for forefront research in atomic physics and many other disciplines. 27 refs., 1 fig., 3 tabs.« less

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.

Guide to bibliographies, books, reviews and compendia of data on atomic collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDaniel, E.W.; Mansky, E.J.

In 1985, the Atlanta atomic physics group published an extensive bibliography on atomic collisions. It differed from the usual in that it contained few references to individual research papers, but instead concentrated on data collections, bibliographies, review articles and books. The present work updates the 1985 from August 1984 to September 1992.

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…

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…

Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition

NASA Astrophysics Data System (ADS)

Parrish, Robert M.; Sherrill, C. David

2014-07-01

We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work through the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in systems with up to 220 atoms and 2845 basis functions.

Spatial assignment of symmetry adapted perturbation theory interaction energy components: The atomic SAPT partition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parrish, Robert M.; Sherrill, C. David, E-mail: sherrill@gatech.edu

2014-07-28

We develop a physically-motivated assignment of symmetry adapted perturbation theory for intermolecular interactions (SAPT) into atom-pairwise contributions (the A-SAPT partition). The basic precept of A-SAPT is that the many-body interaction energy components are computed normally under the formalism of SAPT, following which a spatially-localized two-body quasiparticle interaction is extracted from the many-body interaction terms. For electrostatics and induction source terms, the relevant quasiparticles are atoms, which are obtained in this work through the iterative stockholder analysis (ISA) procedure. For the exchange, induction response, and dispersion terms, the relevant quasiparticles are local occupied orbitals, which are obtained in this work throughmore » the Pipek-Mezey procedure. The local orbital atomic charges obtained from ISA additionally allow the terms involving local orbitals to be assigned in an atom-pairwise manner. Further summation over the atoms of one or the other monomer allows for a chemically intuitive visualization of the contribution of each atom and interaction component to the overall noncovalent interaction strength. Herein, we present the intuitive development and mathematical form for A-SAPT applied in the SAPT0 approximation (the A-SAPT0 partition). We also provide an efficient series of algorithms for the computation of the A-SAPT0 partition with essentially the same computational cost as the corresponding SAPT0 decomposition. We probe the sensitivity of the A-SAPT0 partition to the ISA grid and convergence parameter, orbital localization metric, and induction coupling treatment, and recommend a set of practical choices which closes the definition of the A-SAPT0 partition. We demonstrate the utility and computational tractability of the A-SAPT0 partition in the context of side-on cation-π interactions and the intercalation of DNA by proflavine. A-SAPT0 clearly shows the key processes in these complicated noncovalent interactions, in systems with up to 220 atoms and 2845 basis functions.« less

Atomtronics: Material and Device Physics of Quantum Gases

DTIC Science & Technology

matter physics to electrical engineering. Our projects title Atomtronics: Material and device physics of quantum gases illustrates the chasm we bridged...starting from therich and fundamental physics already revealed with cold atoms systems, then leading to an understanding of the functional materials

Atom loss resonances in a Bose-Einstein condensate.

PubMed

Langmack, Christian; Smith, D Hudson; Braaten, Eric

2013-07-12

Atom loss resonances in ultracold trapped atoms have been observed at scattering lengths near atom-dimer resonances, at which Efimov trimers cross the atom-dimer threshold, and near two-dimer resonances, at which universal tetramers cross the dimer-dimer threshold. We propose a new mechanism for these loss resonances in a Bose-Einstein condensate of atoms. As the scattering length is ramped to the large final value at which the atom loss rate is measured, the time-dependent scattering length generates a small condensate of shallow dimers coherently from the atom condensate. The coexisting atom and dimer condensates can be described by a low-energy effective field theory with universal coefficients that are determined by matching exact results from few-body physics. The classical field equations for the atom and dimer condensates predict narrow enhancements in the atom loss rate near atom-dimer resonances and near two-dimer resonances due to inelastic dimer collisions.

Defect-suppressed atomic crystals in an optical lattice.

PubMed

Rabl, P; Daley, A J; Fedichev, P O; Cirac, J I; Zoller, P

2003-09-12

We present a coherent filtering scheme which dramatically reduces the site occupation number defects for atoms in an optical lattice by transferring a chosen number of atoms to a different internal state via adiabatic passage. With the addition of superlattices it is possible to engineer states with a specific number of atoms per site (atomic crystals), which are required for quantum computation and the realization of models from condensed matter physics, including doping and spatial patterns. The same techniques can be used to measure two-body spatial correlation functions.

Remote preparation of an atomic quantum memory.

PubMed

Rosenfeld, Wenjamin; Berner, Stefan; Volz, Jürgen; 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 87Rb atom. We evaluated the performance of this scheme by the full tomography of the prepared atomic state, reaching an average fidelity of 82%.

Structural Rearrangement of Au-Pd Nanoparticles under Reaction Conditions: An ab Initio Molecular Dynamics Study.

PubMed

Xu, Cong-Qiao; Lee, Mal-Soon; Wang, Yang-Gang; Cantu, David C; Li, Jun; Glezakou, Vassiliki-Alexandra; Rousseau, Roger

2017-02-28

The structure, composition, and atomic distribution of nanoalloys under operating conditions are of significant importance for their catalytic activity. In the present work, we use ab initio molecular dynamics simulations to understand the structural behavior of Au-Pd nanoalloys supported on rutile TiO 2 under different conditions. We find that the Au-Pd structure is strongly dependent on the redox properties of the support, originating from strong metal-support interactions. Under reducing conditions, Pd atoms are inclined to move toward the metal/oxide interface, as indicated by a significant increase of Pd-Ti bonds. This could be attributed to the charge localization at the interface that leads to Coulomb attractions to positively charged Pd atoms. In contrast, under oxidizing conditions, Pd atoms would rather stay inside or on the exterior of the nanoparticle. Moreover, Pd atoms on the alloy surface can be stabilized by hydrogen adsorption, forming Pd-H bonds, which are stronger than Au-H bonds. Our work offers critical insights into the structure and redox properties of Au-Pd nanoalloy catalysts under working conditions.

PEOPLE IN PHYSICS: Atom - from hypothesis to certainty

NASA Astrophysics Data System (ADS)

Lacina, Ales

1999-11-01

The concept of atoms should not be taken for granted. It was developed relatively recently and based on observations in the fields of thermal phenomena, crystallography and chemistry and the crucial discovery of Brownian motion.

10 CFR 1017.30 - Criminal penalty.

Code of Federal Regulations, 2013 CFR

2013-01-01

... INFORMATION Violations § 1017.30 Criminal penalty. Any person who violates section 148 of the Atomic Energy Act or any regulation or order of the Secretary issued under section 148 of the Atomic Energy Act, including these regulations, may be subject to a criminal penalty under section 223 of the Atomic Energy Act...

10 CFR 1017.30 - Criminal penalty.

Code of Federal Regulations, 2012 CFR

2012-01-01

... INFORMATION Violations § 1017.30 Criminal penalty. Any person who violates section 148 of the Atomic Energy Act or any regulation or order of the Secretary issued under section 148 of the Atomic Energy Act, including these regulations, may be subject to a criminal penalty under section 223 of the Atomic Energy Act...

10 CFR 1017.30 - Criminal penalty.

Code of Federal Regulations, 2014 CFR

2014-01-01

... INFORMATION Violations § 1017.30 Criminal penalty. Any person who violates section 148 of the Atomic Energy Act or any regulation or order of the Secretary issued under section 148 of the Atomic Energy Act, including these regulations, may be subject to a criminal penalty under section 223 of the Atomic Energy Act...

"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…

Watching Silica's Dance: Imaging the Structure and Dynamics of the Atomic (Re-) Arrangements in 2D Glass

NASA Astrophysics Data System (ADS)

Muller, David

2014-03-01

Even though glasses are almost ubiquitous--in our windows, on our iPhones, even on our faces--they are also mysterious. Because glasses are notoriously difficult to study, basic questions like: ``How are the atoms arranged? Where and how do glasses break?'' are still under contention. We use aberration corrected transmission electron microscopy (TEM) to image the atoms in a new two-dimensional phase of silica glass - freestanding it becomes the world's thinnest pane of glass at only 3-atoms thick, and take a unique look into these questions. Using atom-by-atom imaging and spectroscopy, we are able to reconstruct the full structure and bonding of this 2D glass and identify it as a bi-tetrahedral layer of SiO2. Our images also strikingly resemble Zachariasen's original cartoon models of glasses, drawn in 1932. As such, our work realizes an 80-year-old vision for easily understandable glassy systems and introduces promising methods to test theoretical predictions against experimental data. We image atoms in the disordered solid and track their motions in response to local strain. We directly obtain ring statistics and pair distribution functions that span short-, medium-, and long-range order, and test these against long-standing theoretical predictions of glass structure and dynamics. We use the electron beam to excite atomic rearrangements, producing surprisingly rich and beautiful videos of how a glass bends and breaks, as well as the exchange of atoms at a solid/liquid interface. Detailed analyses of these videos reveal a complex dance of elastic and plastic deformations, phase transitions, and their interplay. These examples illustrate the wide-ranging and fundamental materials physics that can now be studied at atomic-resolution via transmission electron microscopy of two-dimensional glasses. Work in collaboration with: S. Kurasch, U. Kaiser, R. Hovden, Q. Mao, J. Kotakoski, J. S. Alden, A. Shekhawat, A. A. Alemi, J. P. Sethna, P. L. McEuen, A.V. Krasheninnikov, A. Srivastava, V. Skakalova, J. C. Meyer, and J.H. Smet. This work was supported by the NSF through the Cornell Center for Materials Research (NSF DMR-1120296).

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.

Dipolar and spinor bosonic systems

NASA Astrophysics Data System (ADS)

Yukalov, V. I.

2018-05-01

The main properties and methods of describing dipolar and spinor atomic systems, composed of bosonic atoms or molecules, are reviewed. The general approach for the correct treatment of Bose-condensed atomic systems with nonlocal interaction potentials is explained. The approach is applied to Bose-condensed systems with dipolar interaction potentials. The properties of systems with spinor interaction potentials are described. Trapped atoms and atoms in optical lattices are considered. Effective spin Hamiltonians for atoms in optical lattices are derived. The possibility of spintronics with cold atom is emphasized. The present review differs from the previous review articles by concentrating on a thorough presentation of basic theoretical points, helping the reader to better follow mathematical details and to make clearer physical conclusions.

Atomic Data Needs for X-ray Astronomy

NASA Technical Reports Server (NTRS)

Bautista, Manuel A. (Editor); Kallman, Timothy R. (Editor); Pradhan, Anil K. (Editor)

2000-01-01

This publication contains written versions of most of the invited talks presented at the workshop on "Atomic Data Needs for X-ray Astronomy," which was held at NASA's Goddard Space Flight Center on December 16-17, 1999. The workshop was divided into five major areas: Observational Spectroscopy, Theoretical Calculations of Atomic Data, Laboratory Measurements of Atomic Parameters, Spectra Modeling, and Atomic Databases. These proceedings are expected to be of interest to producers and users of atomic data. Moreover, the contributions presented here have been written in a way that can be used by a general audience of scientists and graduate students in X-ray astronomy, modelling, and in computational and experimental atomic physics.

Soliton Dynamics of an Atomic Spinor Condensate on a Ring Lattice

DTIC Science & Technology

2013-02-22

REPORT Soliton dynamics of an atomic spinor condensate on a Ring Lattice 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We study the dynamics of...8/98) Prescribed by ANSI Std. Z39.18 - Soliton dynamics of an atomic spinor condensate on a Ring Lattice Report Title ABSTRACT We study the dynamics...Report Number Soliton dynamics of an atomic spinor condensat Block 13: Supplementary Note © 2013 . Published in Physical Review A (accepted), Vol. Ed

2016 Summer Series - Mark Kasevich: Quantum Mechanics at Macroscopic Scales

NASA Image and Video Library

2016-06-09

The underpinning of the universe is quantum mechanics. It can be used to explain the observed particle and wave nature of atoms. Atom interferometry uses the wave characteristics of atoms to investigate fundamental physics and advance our understanding of the macroscopic world. NASA is working with Dr. Mark Kasevich to apply this technology to advance astrophysics and improve navigation. In his seminar, Kasevich will delve into the world of atom interferometry, gravitational waves and quantum sensors.

Entangling two transportable neutral atoms via local spin exchange.

PubMed

Kaufman, A M; Lester, B J; Foss-Feig, M; Wall, M L; Rey, A M; Regal, C A

2015-11-12

To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement, and have detected entanglement with macroscopic observables; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms. The local entangling operation is achieved via spin-exchange interactions, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.

Hydrogen storage property of alkali and alkaline-earth metal atoms decorated C24 fullerene: A DFT study

NASA Astrophysics Data System (ADS)

Zhang, Yafei; Cheng, Xinlu

2018-04-01

The hydrogen storage behavior of alkali and alkaline-earth metal (AM = Li, Na, K, Mg, Ca) atoms decorated C24 fullerene was investigated by using density functional theory (DFT) study. Our results indicate that the AM atoms prefer to adsorb atop the center of tetragon of C24 fullerene with the largest binding energy than other possible adsorption sites. Moreover, the hydrogen storage gravimetric density of 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations reaches up to 12.7 wt%, 10.1 wt% and 12 wt%, higher than the year 2020 target from the US department of energy (DOE). Also, the average adsorption energies of H2 molecules of the 24H2/6Li/C24, 24H2/6Na/C24 and 36H2/6Ca/C24 configurations are -0.198 eV/H2, -0.164 eV/H2 and -0.138 eV/H2, locate the desirable range under the physical adsorption at near ambient conditions. These findings will have important implications on designing new hydrogen storage materials in the future.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phuthong, Witchukorn; Huang, Zubin; Wittkopp, Tyler M.

To investigate the dynamics of photosynthetic pigment-protein complexes in vascular plants at high resolution in an aqueous environment, membrane-protruding oxygen-evolving complexes (OECs) associated with photosystem II (PSII) on spinach ( Spinacia oleracea) grana membranes were examined using contact mode atomic force microscopy. This study represents, to our knowledge, the first use of atomic force microscopy to distinguish the putative large extrinsic loop of Photosystem II CP47 reaction center protein (CP47) from the putative oxygen-evolving enhancer proteins 1, 2, and 3 (PsbO, PsbP, and PsbQ) and large extrinsic loop of Photosystem II CP43 reaction center protein (CP43) in the PSII-OEC extrinsicmore » domains of grana membranes under conditions resulting in the disordered arrangement of PSII-OEC particles. Moreover, we observed uncharacterized membrane particles that, based on their physical characteristics and electrophoretic analysis of the polypeptides associated with the grana samples, are hypothesized to be a domain of photosystem I that protrudes from the stromal face of single thylakoid bilayers. Furthermore, our results are interpreted in the context of the results of others that were obtained using cryo-electron microscopy (and single particle analysis), negative staining and freeze-fracture electron microscopy, as well as previous atomic force microscopy studies.« less

Effect of B, N, Ge, Sn, K doping on electronic-transport properties of (5, 0) zigzag carbon nanotube

NASA Astrophysics Data System (ADS)

Kamalian, Monir; Seyed Jalili, Yousef; Abbasi, Afshin

2018-04-01

In this paper the effect of impurity on the electronic properties and quantum conductance of zigzag (5, 0) carbon nanotube have been studied by using the Density Functional Theory (DFT) combined with Non-Equilibrium Green’s Function (NEGF) formalism with TranSIESTA software. The effect of Boron (B), Nitrogen (N), Germanium (Ge), Tin (Sn) and Potassium (K) impurities on the CNT conduction behavior and physical characteristics, like density of states (DOS), band structure, transmission coefficients and quantum conductance was considered and discussed simultaneously. The current‑voltage (I‑V) curves of all the proposed models were studied for comparative study under low-bias conditions. The distinct changes in conductance reported as the positions, number and type of dopants was varied in central region of the CNT between two electrodes at different bias voltages. This suggested conductance enhancement mechanism for the charge transport in the doped CNT at different positions is important for the design of CNT based nanoelectronic devices. The results show that Germanium, Tin and Potassium dopant atoms has increased the conductance of the model manifold than other doping atoms furthermore 10 Boron and 10 Nitrogen dopant atoms showed the amazing property of Negative Differential Resistance (NDR).

A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

NASA Technical Reports Server (NTRS)

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

2000-01-01

We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

2010-01-01

Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

Adaptive local basis set for Kohn–Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Gaigong; Lin, Lin, E-mail: linlin@math.berkeley.edu; Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn–Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann–Feynmanmore » forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Since the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann–Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H{sub 2} and liquid Al–Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature.« less

Adaptive local basis set for Kohn–Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

DOE PAGES

Zhang, Gaigong; Lin, Lin; Hu, Wei; ...

2017-01-27

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn–Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann–Feynmanmore » forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Sin ce the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann–Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H 2 and liquid Al–Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature.« less

Adaptive local basis set for Kohn–Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Gaigong; Lin, Lin; Hu, Wei

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn–Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann–Feynmanmore » forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Sin ce the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann–Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H 2 and liquid Al–Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature.« less

Adaptive local basis set for Kohn-Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

NASA Astrophysics Data System (ADS)

Zhang, Gaigong; Lin, Lin; Hu, Wei; Yang, Chao; Pask, John E.

2017-04-01

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn-Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann-Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Since the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the Hellmann-Feynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H2 and liquid Al-Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature.

Spectr-W3 Online Database On Atomic Properties Of Atoms And Ions

NASA Astrophysics Data System (ADS)

Faenov, A. Ya.; Magunov, A. I.; Pikuz, T. A.; Skobelev, I. Yu.; Loboda, P. A.; Bakshayev, N. N.; Gagarin, S. V.; Komosko, V. V.; Kuznetsov, K. S.; Markelenkov, S. A.

2002-10-01

Recent progress in the novel information technologies based on the World-Wide Web (WWW) gives a new possibility for a worldwide exchange of atomic spectral and collisional data. This facilitates joint efforts of the international scientific community in basic and applied research, promising technological developments, and university education programs. Special-purpose atomic databases (ADBs) are needed for an effective employment of large-scale datasets. The ADB SPECTR developed at MISDC of VNIIFTRI has been used during the last decade in several laboratories in the world, including RFNC-VNIITF. The DB SPECTR accumulates a considerable amount of atomic data (about 500,000 records). These data were extracted from publications on experimental and theoretical studies in atomic physics, astrophysics, and plasma spectroscopy during the last few decades. The information for atoms and ions comprises the ionization potentials, the energy levels, the wavelengths and transition probabilities, and, to a lesser extent, -- also the autoionization rates, and the electron-ion collision cross-sections and rates. The data are supplied with source references and comments elucidating the details of computations or measurements. Our goal is to create an interactive WWW information resource based on the extended and updated Web-oriented database version SPECTR-W3 and its further integration into the family of specialized atomic databases on the Internet. The version will incorporate novel experimental and theoretical data. An appropriate revision of the previously accumulated data will be performed from the viewpoint of their consistency to the current state-of-the-art. We are particularly interested in cooperation for storing the atomic collision data. Presently, a software shell with the up-to-date Web-interface is being developed to work with the SPECTR-W3 database. The shell would include the subsystems of information retrieval, input, update, and output in/from the database and present the users a handful of capabilities to formulate the queries with various modes of the search prescriptions, to present the information in tabular, graphic, and alphanumeric form using the formats of the text and HTML documents. The SPECTR-W3 Website is being arranged now and is supposed to be freely accessible round-the-clock on a dedicated Web server at RFNC VNIITF. The Website is being created with the employment of the advanced Internet technologies and database development techniques by using the up-to-date software of the world leading software manufacturers. The SPECTR-W3 ADB FrontPage would also include a feedback channel for the user comments and proposals as well as the hyperlinks to the Websites of the other ADBs and research centers in Europe, the USA, the Middle and Far East, running the investigations in atomic physics, plasma spectroscopy, astrophysics, and in adjacent areas. The effort is being supported by the International Science and Technology Center under the project sharp/mesh/hash1785-01.

Laboratory Investigations of Mesospheric Ice Surfaces: Absence of Dangling Bonds in the Presence of Atomic Oxygen

NASA Astrophysics Data System (ADS)

Boulter, J. E.; Morgan, C. G.; Marschall, J.

2006-05-01

Remote observations of PMCs have become more sophisticated and have increased in geographic and temporal coverage, while numerical models have advanced in detail and predictive power. Together, these advances enable new questions of PMC morphology, optical properties, and microphysical processes in their formation and dissipation. Laboratory investigations also advance this understanding, simulating physical and chemical processes unique to this atmospheric region under comparable conditions. In this work, ice deposition experiments in the presence of microwave discharge-dissociated molecular oxygen suggest heterogeneous interactions between dangling OH bonds on the ice surface and atomic oxygen. Ice films deposited on a gold substrate at temperatures of 115, 130, and 140 K from oxygen/water gas mixtures representative of the summertime polar mesosphere exhibit infrared absorption features characteristic of dangling bonds, whereas films grown in the presence of atomic oxygen do not. Dangling bond spectral features are shown to diminish rapidly when the microwave discharge is activated during ice deposition. Similar decreases were not seen when the gas stream was heated or when the ice film was slowly annealed from 130 to 160 K. One interpretation of these results is that atomic oxygen binds to dangling bond sites during ice growth, a phenomenon that may also occur during the formation of ice particles observed just below the cold summertime mesopause.

Mechanical behavior enhancement of defective graphene sheet employing boron nitride coating via atomistic study

NASA Astrophysics Data System (ADS)

Setoodeh, A. R.; Badjian, H.

2017-12-01

The most stable form of boron nitride polymorph naming hexagonal boron nitride sheet has recently been widely concerned like graphite due to its interesting features such as electrical insulation and high thermal conductivity. In this study, the molecular dynamic simulations are implemented to investigate the mechanical properties of single-layer graphene sheets under tensile and compressive loadings in the absence and presence of boron-nitride coating layers. In this introduced hybrid nanostructure, the benefit of combining both individual interesting features of graphene and boron-nitride sheets such as exceptional mechanical and electrical properties can be simultaneously achieved for future potential application in nano devices. The influences of chiral indices, boundary conditions and presence of mono-atomic vacancy defects as well as coating dimension on the mechanical behavior of the resulted hybrid structure are reported. The interatomic forces between the atoms are modeled by employing the AIREBO and Tersoff-Brenner potentials for carbon-carbon and boron-nitrogen atoms in each layer, respectively. Furthermore, the van der Waal interlayer forces of carbon-boron and carbon-nitrogen are estimated by the Lennard-Jones potential field. Besides the potential improvement in electrical and physical properties of the nanostructure, it is demonstrated that the buckling load capacity of the fully coated graphene sheet with 3% concentration of mono-atomic vacancy defects noticeably enhances by amounts of 24.1%.

Multidomain proteins under force

NASA Astrophysics Data System (ADS)

Valle-Orero, Jessica; Andrés Rivas-Pardo, Jaime; Popa, Ionel

2017-04-01

Advancements in single-molecule force spectroscopy techniques such as atomic force microscopy and magnetic tweezers allow investigation of how domain folding under force can play a physiological role. Combining these techniques with protein engineering and HaloTag covalent attachment, we investigate similarities and differences between four model proteins: I10 and I91—two immunoglobulin-like domains from the muscle protein titin, and two α + β fold proteins—ubiquitin and protein L. These proteins show a different mechanical response and have unique extensions under force. Remarkably, when normalized to their contour length, the size of the unfolding and refolding steps as a function of force reduces to a single master curve. This curve can be described using standard models of polymer elasticity, explaining the entropic nature of the measured steps. We further validate our measurements with a simple energy landscape model, which combines protein folding with polymer physics and accounts for the complex nature of tandem domains under force. This model can become a useful tool to help in deciphering the complexity of multidomain proteins operating under force.

Atomic-Resolution Spectrum Imaging of Semiconductor Nanowires.

PubMed

Zamani, Reza R; Hage, Fredrik S; Lehmann, Sebastian; Ramasse, Quentin M; Dick, Kimberly A

2018-03-14

Over the past decade, III-V heterostructure nanowires have attracted a surge of attention for their application in novel semiconductor devices such as tunneling field-effect transistors (TFETs). The functionality of such devices critically depends on the specific atomic arrangement at the semiconductor heterointerfaces. However, most of the currently available characterization techniques lack sufficient spatial resolution to provide local information on the atomic structure and composition of these interfaces. Atomic-resolution spectrum imaging by means of electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) is a powerful technique with the potential to resolve structure and chemical composition with sub-angstrom spatial resolution and to provide localized information about the physical properties of the material at the atomic scale. Here, we demonstrate the use of atomic-resolution EELS to understand the interface atomic arrangement in three-dimensional heterostructures in semiconductor nanowires. We observed that the radial interfaces of GaSb-InAs heterostructure nanowires are atomically abrupt, while the axial interface in contrast consists of an interfacial region where intermixing of the two compounds occurs over an extended spatial region. The local atomic configuration affects the band alignment at the interface and, hence, the charge transport properties of devices such as GaSb-InAs nanowire TFETs. STEM-EELS thus represents a very promising technique for understanding nanowire physical properties, such as differing electrical behavior across the radial and axial heterointerfaces of GaSb-InAs nanowires for TFET applications.

Correlation of experimentally measured atomic scale properties of EUV photoresist to modeling performance: an exploration

NASA Astrophysics Data System (ADS)

Kandel, Yudhishthir; Chandonait, Jonathan; Melvin, Lawrence S.; Marokkey, Sajan; Yan, Qiliang; Grzeskowiak, Steven; Painter, Benjamin; Denbeaux, Gregory

2017-03-01

Extreme ultraviolet (EUV) lithography at 13.5 nm stands at the crossroads of next generation patterning technology for high volume manufacturing of integrated circuits. Photo resist models that form the part of overall pattern transform model for lithography play a vital role in supporting this effort. The physics and chemistry of these resists must be understood to enable the construction of accurate models for EUV Optical Proximity Correction (OPC). In this study, we explore the possibility of improving EUV photo-resist models by directly correlating the parameters obtained from experimentally measured atomic scale physical properties; namely, the effect of interaction of EUV photons with photo acid generators in standard chemically amplified EUV photoresist, and associated electron energy loss events. Atomic scale physical properties will be inferred from the measurements carried out in Electron Resist Interaction Chamber (ERIC). This study will use measured physical parameters to establish a relationship with lithographically important properties, such as line edge roughness and CD variation. The data gathered from these measurements is used to construct OPC models of the resist.

Distinguishing between evidence and its explanations in the steering of atomic clocks

NASA Astrophysics Data System (ADS)

Myers, John M.; Hadi Madjid, F.

2014-11-01

Quantum theory reflects within itself a separation of evidence from explanations. This separation leads to a known proof that: (1) no wave function can be determined uniquely by evidence, and (2) any chosen wave function requires a guess reaching beyond logic to things unforeseeable. Chosen wave functions are encoded into computer-mediated feedback essential to atomic clocks, including clocks that step computers through their phases of computation and clocks in space vehicles that supply evidence of signal propagation explained by hypotheses of spacetimes with metric tensor fields. The propagation of logical symbols from one computer to another requires a shared rhythm-like a bucket brigade. Here we show how hypothesized metric tensors, dependent on guesswork, take part in the logical synchronization by which clocks are steered in rate and position toward aiming points that satisfy phase constraints, thereby linking the physics of signal propagation with the sharing of logical symbols among computers. Recognizing the dependence of the phasing of symbol arrivals on guesses about signal propagation transports logical synchronization from the engineering of digital communications to a discipline essential to physics. Within this discipline we begin to explore questions invisible under any concept of time that fails to acknowledge unforeseeable events. In particular, variation of spacetime curvature is shown to limit the bit rate of logical communication.

Characterization of Graphene Grown Directly on Crystalline Substrates

NASA Astrophysics Data System (ADS)

Rothwell, Sara L.

Graphene has become one of the most popular materials under research, particularly since the 2010 Nobel Prize in Physics. Many visions posit that graphene electronics will be some of the fastest and smallest circuitry physically feasible, however before this becomes reality the scientific community must gain a firm handle on the creation of semiconducting varieties of graphene. In addition, well understood epitaxial growth of graphene on insulating materials will add to the facility of fabricating all-carbon electronics. This thesis presents experimental work detailing the growth of pristine graphene grown on sapphire (GOS) through the thermal decomposition of acetylene, and the electronic characterization of graphene grown on nitrogen-seeded silicon carbide (NG), a semiconducting variety of graphene grown in collaboration with researchers at Georgia Institute of Technology and Rutgers University. GOS displays turbostratic stacking and characteristics of monolayer graphene as analyzed by Raman spectroscopy and atomic force microscopy. Scanning tunneling microscopy characterization of NG illustrates a topography of pleats from 0.5-2 nm tall, 1-4 nm thick, and 1-20 nm long, as well as atomically flat plateaus and other areas of intermixed features. Scanning tunneling spectroscopy measurements across NG features show peaks interpreted as Landau levels induced by strain. Analysis of these Landau levels in coordination with previous characterization concludes that a model employing a bandgap fits best.

Theoretical study on the interactions between chlordecone hydrate and acidic surface groups of activated carbon under basic pH conditions.

PubMed

Melchor-Rodríguez, Kenia; Gamboa-Carballo, Juan José; Ferino-Pérez, Anthuan; Passé-Coutrin, Nady; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

2018-05-01

A theoretical study of the influence of acidic surface groups (SG) of activated carbon (AC) on chlordecone hydrate (CLDh) adsorption is presented, in order to help understanding the adsorption process under basic pH conditions. A seven rings aromatic system (coronene) with a functional group in the edge was used as a simplified model of AC to evaluate the influence of SG in the course of adsorption from aqueous solution at basic pH conditions. Two SG were modeled in their deprotonated form: carboxyl and hydroxyl (COO - and O - ), interacting with CLDh. In order to model the solvation process, all systems under study were calculated with up to three water molecules. Multiple Minima Hypersurface (MMH) methodology was employed to study the interactions of CLDh with SG on AC using PM7 semiempirical Hamiltonian, to explore the potential energy surfaces of the systems and evaluate their thermodynamic association energies. The re-optimization of representative structures obtained from MMH was done using M06-2X Density Functional Theory. The Quantum Theory of Atoms in Molecules (QTAIM) was used to characterize the interaction types. As result, the association of CLDh with acidic SG at basic pH conditions preferentially occurs between the two alcohol groups of CLDh with COO - and O - groups and by dispersive interactions of chlorine atoms of CLDh with the graphitic surface. On the other hand, the presence of covalent interactions between the negatively charged oxygen of SG and one hydrogen atom of CLDh alcohol groups (O - ⋯HO interactions) without water molecules, was confirmed by QTAIM study. It can be concluded that the interactions of CLDh with acidic SG of AC under basic pH conditions confirms the physical mechanisms of adsorption process. Copyright © 2018 Elsevier Inc. All rights reserved.

Hanford Atomic Products Operation monthly report for June 1955

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1955-07-28

This is the monthly report for the Hanford Atomic Products Operation, June, 1955. Metallurgy, reactor fuels, chemistry, dosimetry, separation processes, reactor technology, financial activities, visits, biology operation, physics and instrumentation research, and employee relations are discussed.

Hanford Atomic Products Operation monthly report, January 1956

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1956-02-24

This is the monthly report for the Hanford Atomic Laboratories Products Operation, February, 1956. Metallurgy, reactor fuels, chemistry, dosimetry, separation processes, reactor technology, financial activities, visits, biology operation, physics and instrumentation research, and employee relations are discussed.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santarius, John F.; Emmert, Gilbert A.

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 themore » 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.« less

Experimental realization of a subwavelength optical potential based on atomic dark state

NASA Astrophysics Data System (ADS)

Wang, Yang; Subhankar, Sarthak; Rolston, Steven; Porto, James

2017-04-01

As a well-established tool optical lattice (OL) provides the unique opportunity to exploit the rich manybody physics. However, ``traditional'' OL, either via laser beam interference or direct projection with spatial light modulator, has a length scale around the wavelength (0.1 10 λ) that is set by diffraction, a fundamental limit from the wave nature of the light. Recent theoretical proposals suggest an alternative route, where the geometric potential, stemming from light-atom interaction, can be engineered to generate a much finer potential landscape which is essentially limited by the wave nature of the slow moving cold atoms. We report on the progress towards an experimental realization of these ideas using degenerate fermionic ytterbium atoms. Such subwavelength optical potential could open the gate to study physics beyond currently available parameter regimes, such as enhanced super-exchange coupling, magnetic dipolar coupling, and tunnel junction in atomtronics.

Chemical effects of alkali atoms on critical temperature in superconducting alkali-doped fullerides

NASA Astrophysics Data System (ADS)

Hetfleisch, F.; Gunnarsson, O.; Srama, R.; Han, J. E.; Stepper, M.; Roeser, H.-P.; Bohr, A.; Lopez, J. S.; Mashmool, M.; Roth, S.

2018-03-01

Alkali metal doped fullerides (A3C60) are superconductors with critical temperatures, Tc, extending up to 38 K. Tc is known to depend strongly on the lattice parameter a, which can be adjusted by physical or chemical pressure. In the latter case an alkali atom is replaced by a different sized one, which changes a. We have collected an extensive data base of experimental data for Tc from very early up to recent measurements. We disentangle alkali atom chemical effects on Tc, beyond the well-known consequences of changing a. It is found that Tc, for a fixed a, is typically increased as smaller alkali atoms are replaced by larger ones, except for very large a. Possible reasons for these results are discussed. Although smaller in size than the lattice parameter contribution, the chemical effect is not negligible and should be considered in future physical model developments.

Synthesis and Characteristics of HgCdSe for IR Detection

DTIC Science & Technology

2014-03-11

Photoelectron Spectroscopy Study of Oxide Removal Using Atomic Hydrogen for Large-Area II–VI Material Growth, Journal of Electronic Materials...Workshop on the Physics and Chemistry of II-VI Materials, Chicago IL (October 1-3, 2013) “Use of Atomic Hydrogen to Prepare GaSb(211)B and GaSb(100...Workshop on the Physics and Chemistry of II-VI Materials, Chicago IL (October, 2011) "Xray photoelectron spectroscopy study of oxide removal using

Quantum Computation and Simulation Using Neutral Fermionic Atoms

DTIC Science & Technology

2014-06-06

labeled n = 1) Efimov trimer crosses the three-atom scattering threshold. Working in the context of nuclear physics in the early 1970’s, Vitaly Efimov...permit the observation of anti-ferromagnetic ordering in the Hubbard model. (a) Papers published in peer-reviewed journals ( N /A for none) Enter List of...Physics, (06 2011): 0. doi: TOTAL: 7 Number of Papers published in peer-reviewed journals: (b) Papers published in non-peer-reviewed journals ( N /A for

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.

Physics in perspective. Volume 2, part A: The core subfields of physics

NASA Technical Reports Server (NTRS)

1972-01-01

Panel reports to the Survey Committee are presented to provide detailed technical background and documentation for committee findings, and to indicate the vitality and strength of the subfields of physics. Included are the core subfields of acoustics, optics, condensed matter, plasmas and fluids, atomic molecular and electron physics, nuclear physics, and elementary particle physics.

Bose-Einstein Condensate-Hidden Riches for New Forms of Technology and Energy Generation; Potential for Glimpse into Inner Reality

NASA Astrophysics Data System (ADS)

Reed, Don

With the announcement of the recent successful production of a Bose-Einstein condensate (BEC) of photons, a circle has been completed which started in 1925 with the vision of Albert Einstein and Satyendra Nath Bose - a sustained macroscopic condensed state of matter where all atoms are in the same lowest quantum state. The creation of an all-optical BEC, involving a surprisingly straightforward "tabletop" method which bypasses the normally requisite laser/evaporative cooling equipment and ultra-high vacuum chambers necessary for production of the standard delicate atomic BEC, elevates this phenomenon to a new level well beyond its current perception as mere laboratory curiosity. Accordingly, this development certainly heralds eventual incorporation of atomic and photon BECs as standard operating components of energy-efficient mechanical, optical and electrical systems, implying novel ingenious engineering protocols amenable to all the tools of non-linear and quantum optics. Pointing towards such a promising technological future are the suggestion that a photon BEC could serve as a new high-energy ultra-violet (UV) laser photon source, as well as the recent unprecedented implementation of a closed-loop atom circuit (toroidal atomic BEC) demonstrating precise control of superfluid current flow, forecasting the coveted development of an atomic SQUID. Perhaps more significantly, the new highly robust and manageable optical BEC will allow heretofore unfathomable precise probing of the atomic and nano-levels of nature, affording novel high-quality testing procedures of the major foundations of quantum mechanics itself. Such a primary advancement, providing a clearer glimpse into the microscopic realms, may present us as never before with an unprecedented view of the quantum engine that underpins physical reality itself and help place the contextual nature of entanglement and quantum superposition on a firmer foundation. Thus, further progress in achieving mastery over the precise flexible manipulation of BEC states could demonstrate that quantum contextuality might be an unsuspected over-arching archetypal principle in nature, leading to new insight in regards to the interpretation of quantum mechanics as applied to all levels of nature. Moreover, it will be shown that this concealed and hence heretofore unsuspected contextual aspect of natural laws, as exemplified by the dynamics underlying BEC structure, could be brought to bear to account for physical anomalies inexplicable using current paradigms, such as the claimed energy yields from low-energy nuclear reactions (as represented by the so-called process of "cold fusion"), making this phenomenon more tractable and rendered less controversial.

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…

Rugged, Tunable Extended-Cavity Diode Laser

NASA Technical Reports Server (NTRS)

Moore, Donald; Brinza, David; Seidel, David; Klipstein, William; Choi, Dong Ho; Le, Lam; Zhang, Guangzhi; Iniguez, Roberto; Tang, Wade

2007-01-01

A rugged, tunable extended-cavity diode laser (ECDL) has been developed to satisfy stringent requirements for frequency stability, notably including low sensitivity to vibration. This laser is designed specifically for use in an atomic-clock experiment to be performed aboard the International Space Station (ISS). Lasers of similar design would be suitable for use in terrestrial laboratories engaged in atomic-clock and atomic-physics research.

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…

Resonant Laser Manipulation of an Atomic Beam

DTIC Science & Technology

2010-07-01

similar species such as alkali metals . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...resonant laser-atom interaction with other rarefied and collisional solvers for similar species such as alkali metals . Keywords: atomic beam, cesium...a target flow over length scales which push the limits of physical manufacture. The ability to create masks, beam blocks, controlling electric

An exacting transition probability measurement - a direct test of atomic many-body theories.

PubMed

Dutta, Tarun; De Munshi, Debashis; Yum, Dahyun; Rebhi, Riadh; Mukherjee, Manas

2016-07-19

A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P3/2 level of the barium ion, with precision below 0.5%. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with a precision better than 1%. Furthermore, enhancing our understanding of the barium puzzle in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with a precision below one percent and more importantly with no known systematic uncertainties. The unique measurement protocol proposed here can be easily extended to any decay with more than two channels and hence paves the way for measuring the branching fractions of other hydrogenic atoms with no significant systematic uncertainties.

Visualising reacting single atoms under controlled conditions: Advances in atomic resolution in situ Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM)

NASA Astrophysics Data System (ADS)

Boyes, Edward D.; Gai, Pratibha L.

2014-02-01

Advances in atomic resolution Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM) for probing gas-solid catalyst reactions in situ at the atomic level under controlled reaction conditions of gas environment and temperature are described. The recent development of the ESTEM extends the capability of the ETEM by providing the direct visualisation of single atoms and the atomic structure of selected solid state heterogeneous catalysts in their working states in real-time. Atomic resolution E(S)TEM provides a deeper understanding of the dynamic atomic processes at the surface of solids and their mechanisms of operation. The benefits of atomic resolution-E(S)TEM to science and technology include new knowledge leading to improved technological processes with substantial economic benefits, improved healthcare, reductions in energy needs and the management of environmental waste generation. xml:lang="fr"

40 CFR 23.9 - Timing of Administrator's action under the Atomic Energy Act.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 1 2014-07-01 2014-07-01 false Timing of Administrator's action under the Atomic Energy Act. 23.9 Section 23.9 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Atomic Energy Act. Unless the Administrator otherwise explicitly provides in a particular order, the time...

40 CFR 23.9 - Timing of Administrator's action under the Atomic Energy Act.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Timing of Administrator's action under the Atomic Energy Act. 23.9 Section 23.9 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Atomic Energy Act. Unless the Administrator otherwise explicitly provides in a particular order, the time...

40 CFR 23.9 - Timing of Administrator's action under the Atomic Energy Act.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 1 2011-07-01 2011-07-01 false Timing of Administrator's action under the Atomic Energy Act. 23.9 Section 23.9 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Atomic Energy Act. Unless the Administrator otherwise explicitly provides in a particular order, the time...

40 CFR 23.9 - Timing of Administrator's action under the Atomic Energy Act.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 1 2012-07-01 2012-07-01 false Timing of Administrator's action under the Atomic Energy Act. 23.9 Section 23.9 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Atomic Energy Act. Unless the Administrator otherwise explicitly provides in a particular order, the time...

40 CFR 23.9 - Timing of Administrator's action under the Atomic Energy Act.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 1 2013-07-01 2013-07-01 false Timing of Administrator's action under the Atomic Energy Act. 23.9 Section 23.9 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Atomic Energy Act. Unless the Administrator otherwise explicitly provides in a particular order, the time...

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

Between Industry and Academia: A Physicist's Experiences at The Aerospace Corporation

NASA Astrophysics Data System (ADS)

Camparo, James

2005-03-01

The Aerospace Corporation is a nonprofit company whose purposes are exclusively scientific: to provide research, development, and advisory services for space programs that serve the national interest, primarily the Air Force's Space and Missile Systems Center and the National Reconnaissance Office. The corporation's laboratory has a staff of about 150 scientists who conduct research in fields ranging from Space Sciences to Material Sciences and from Analytical Chemistry to Atomic Physics. As a consequence, Aerospace stands midway between an industrial research laboratory, focused on product development, and academic/national laboratories focused on basic science. Drawing from Dr. Camparo's personal experiences, the presentation will discuss advantages and disadvantages of a career at Aerospace, including the role of publishing in peer-reviewed journals and the impact of work on family life. Additionally, the presentation will consider the balance between basic physics, applied physics, and engineering in the work at Aerospace. Since joining Aerospace in 1981, Dr. Camparo has worked as an atomic physicist specializing in the area of atomic clocks, and has had the opportunity to experiment and publish on a broad range of research topics including: the stochastic-field/atom interaction, radiation effects on semiconductor materials, and stellar scintillation.

Non-equilibrium Transport in Carbon based Adsorbate Systems

NASA Astrophysics Data System (ADS)

Fürst, Joachim; Brandbyge, Mads; Stokbro, Kurt; Jauho, Antti-Pekka

2007-03-01

We have used the Atomistix Tool Kit(ATK) and TranSIESTA[1] packages to investigate adsorption of iron atoms on a graphene sheet. The technique of both codes is based on density functional theory using local basis sets[2], and non-equilibrium Green's functions (NEGF) to calculate the charge distribution under external bias. Spin dependent electronic structure calculations are performed for different iron coverages. These reveal adsorption site dependent charge transfer from iron to graphene leading to screening effects. Transport calculations show spin dependent scattering of the transmission which is analysed obtaining the transmission eigenchannels for each spin type. The phenomena of electromigration of iron in these systems at finite bias will be discussed, estimating the so-called wind force from the reflection[3]. [1] M. Brandbyge, J.-L. Mozos, P. Ordejon, J. Taylor, and K. Stokbro. Physical Review B (Condensed Matter and Materials Physics), 65(16):165401/11-7, 2002. [2] Jose M. Soler, Emilio Artacho, Julian D. Gale, Alberto Garcia, Javier Junquera, Pablo Ordejon, and Daniel Sanchez-Portal. Journal of Physics Condensed Matter, 14(11):2745-2779, 2002. [3] Sorbello. Theory of electromigration. Solid State Physics, 1997.

New Concepts and Fermilab Facilities for Antimatter Research

NASA Astrophysics Data System (ADS)

Jackson, Gerald

2008-04-01

There has long been significant interest in continuing antimatter research at the Fermi National Accelerator Laboratory. Beam kinetic energies ranging from 10 GeV all the way down to the eV scale and below are of interest. There are three physics missions currently being developed: the continuation of charmonium physics utilizing an internal target; atomic physics with in-flight generated antihydrogen atoms; and deceleration to thermal energies and paasage of antiprotons through a grating system to determine their gravitation acceleration. Non-physics missions include the study of medical applications, tests of deep-space propulsion concepts, low-risk testing of nuclear fuel elements, and active interrogation for smuggled nuclear materials in support of homeland security. This paper reviews recent beam physics and accelerator technology innovations in the development of methods and new Fermilab facilities for the above missions.

Atomic force microscopy and nanoindentation investigation of polydimethylsiloxane elastomeric substrate compliancy for various sputtered thin film morphologies.

PubMed

Maji, Debashis; Das, Soumen

2018-03-01

Crack free electrically continuous metal thin films over soft elastomeric substrates play an integral part in realization of modern day flexible bioelectronics and biosensors. Under nonoptimized deposition conditions, delamination, and/or cracking of the top film as well as the underlying soft substrate hinders optimal performance of these devices. Hence it is very important to understand and control not only the various deposition factors like power, time, or deposition pressure but also investigate the various interfacial physics playing a critical role in assuring thin film adhesion and substrate compliancy. In the present study, various nanomechanical information of the underlying substrate, namely, crack profile, average roughness, Young's modulus, and adhesion force were studied for uncracked and cracked polydimethylsiloxane (PDMS) surfaces along with pristine and conventional plasma treated PDMS samples as control. Quantification of the above parameters were done using three-dimensional surface profiler, scanning electron microscopy, nanoindentation, and atomic force microscopy techniques to elucidate the modulus range, average roughness, and adhesion force. Comparative analysis with control revealed remarkable similarity between increased modulus values, increased surface roughness, and reduced adhesion force accounting for reduced substrate compliancy and resulting in film cracking or buckling which are critical for development of various bioflexible devices. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 725-737, 2018. © 2017 Wiley Periodicals, Inc.

Quasi-periodicity of vector solitons in a graphene mode-locked fiber laser

NASA Astrophysics Data System (ADS)

Song, Yu Feng; Li, Lei; Tang, Ding Yuan; Shen, De Yuan

2013-12-01

We report on the experimental observation of quasi-periodic dynamics of vector solitons in an erbium-doped fiber laser passively mode-locked with atomic layer graphene. Apart from the stable polarization-locked vector soliton emission, it was found that under certain conditions the fiber laser could also emit vector solitons with quasi-periodic pulse energy variation and polarization rotation during the cavity roundtrips. We show that the physical mechanism for the quasi-periodic vector soliton evolution is cavity-induced soliton modulation instability. Quasi-periodic evolution of multiple vector solitons was also observed in the same laser.

Computing Interactions Of Free-Space Radiation With Matter

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Cucinotta, F. A.; Shinn, J. L.; Townsend, L. W.; Badavi, F. F.; Tripathi, R. K.; Silberberg, R.; Tsao, C. H.; Badwar, G. D.

1995-01-01

High Charge and Energy Transport (HZETRN) computer program computationally efficient, user-friendly package of software adressing problem of transport of, and shielding against, radiation in free space. Designed as "black box" for design engineers not concerned with physics of underlying atomic and nuclear radiation processes in free-space environment, but rather primarily interested in obtaining fast and accurate dosimetric information for design and construction of modules and devices for use in free space. Computational efficiency achieved by unique algorithm based on deterministic approach to solution of Boltzmann equation rather than computationally intensive statistical Monte Carlo method. Written in FORTRAN.

Characteristics of a high-power RF source of negative hydrogen ions for neutral beam injection into controlled fusion devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdrashitov, G. F.; Belchenko, Yu. I.; Gusev, I. A.

An injector of hydrogen atoms with an energy of 0.5–1 MeV and equivalent current of up to 1.5 A for purposes of controlled fusion research is currently under design at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. Within this project, a multiple-aperture RF surface-plasma source of negative hydrogen ions is designed. The source design and results of experiments on the generation of a negative ion beam with a current of >1 A in the long-pulse mode are presented.

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

NASA Astrophysics Data System (ADS)

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

2011-07-01

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