Search for Hidden Particles: a new experiment proposal

NASA Astrophysics Data System (ADS)

De Lellis, G.

2015-08-01

Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. We propose a new experiment meant to search for very weakly coupled particles in the few GeV mass domain. The existence of such particles, foreseen in different models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and it could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. In particular, tau anti-neutrinos have not been observed so far. We therefore propose an experiment to search for hidden particles and study tau neutrino physics at the same time.

Search for Hidden Particles (SHiP): a new experiment proposal

NASA Astrophysics Data System (ADS)

De Lellis, G.

2015-06-01

Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. We propose a new experimental facility meant to search for very weakly coupled particles in the few GeV mass domain. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. In particular, tau anti-neutrinos have not been observed so far. We therefore propose an experiment to search for hidden particles and study tau neutrino physics at the same time.

String Theory, the Crisis in Particle Physics and the Ascent of Metaphoric Arguments

NASA Astrophysics Data System (ADS)

Schroer, Bert

This essay presents a critical evaluation of the concepts of string theory and its impact on particle physics. The point of departure is a historical review of four decades of string theory within the broader context of six decades of failed attempts at an autonomous S matrix approach to particle theory. The central message, contained in Secs. 5 and 6, is that string theory is not what its name suggests, namely a theory of objects in space-time whose localization is string-instead of pointlike. Contrary to popular opinion, the oscillators corresponding to the Fourier models of a quantum-mechanical string do not become embedded in space-time and neither does the "range space" of a chiral conformal QFT acquire the interpretation of stringlike-localized quantum matter. Rather, string theory represents a solution to a problem which enjoyed some popularity in the 1960s: find a principle which, similar to the SO(4,2) group in the case of the hydrogen spectrum, determines an infinite component wave function with a (realistic) mass/spin spectrum. Instead of the group theory used in the old failed attempts, it creates this mass/spin spectrum by combining an internal oscillator quantum mechanics with a pointlike-localized quantum-field-theoretic object, i.e. the mass/spin tower "sits" over one point and does not arise from a wiggling string in space-time. The widespread acceptance of a theory whose interpretation has been based on metaphoric reasoning had a corroding influence on particle theory, a point which will be illustrated in the last section with some remarks of a more sociological nature. These remarks also lend additional support to observations on connections between the discourse in particle physics and the present Zeitgeist of the post-Cold War period that are made in the introduction.

Material point method of modelling and simulation of reacting flow of oxygen

NASA Astrophysics Data System (ADS)

Mason, Matthew; Chen, Kuan; Hu, Patrick G.

2014-07-01

Aerospace vehicles are continually being designed to sustain flight at higher speeds and higher altitudes than previously attainable. At hypersonic speeds, gases within a flow begin to chemically react and the fluid's physical properties are modified. It is desirable to model these effects within the Material Point Method (MPM). The MPM is a combined Eulerian-Lagrangian particle-based solver that calculates the physical properties of individual particles and uses a background grid for information storage and exchange. This study introduces chemically reacting flow modelling within the MPM numerical algorithm and illustrates a simple application using the AeroElastic Material Point Method (AEMPM) code. The governing equations of reacting flows are introduced and their direct application within an MPM code is discussed. A flow of 100% oxygen is illustrated and the results are compared with independently developed computational non-equilibrium algorithms. Observed trends agree well with results from an independently developed source.

The Gibbs paradox and the physical criteria for indistinguishability of identical particles

NASA Astrophysics Data System (ADS)

Unnikrishnan, C. S.

2016-08-01

Gibbs paradox in the context of statistical mechanics addresses the issue of additivity of entropy of mixing gases. The usual discussion attributes the paradoxical situation to classical distinguishability of identical particles and credits quantum theory for enabling indistinguishability of identical particles to solve the problem. We argue that indistinguishability of identical particles is already a feature in classical mechanics and this is clearly brought out when the problem is treated in the language of information and associated entropy. We pinpoint the physical criteria for indistinguishability that is crucial for the treatment of the Gibbs’ problem and the consistency of its solution with conventional thermodynamics. Quantum mechanics provides a quantitative criterion, not possible in the classical picture, for the degree of indistinguishability in terms of visibility of quantum interference, or overlap of the states as pointed out by von Neumann, thereby endowing the entropy expression with mathematical continuity and physical reasonableness.

A demonstration of particle duality of light

NASA Astrophysics Data System (ADS)

Jiang, Haili; Liu, Zhihai; Sun, Qiuhua; Zhao, Yancheng

2017-08-01

The need of understanding and teaching about wave-particle duality if light with gets more and more apparent in the background of the attention of modern physics. As early as the beginning of twentieth Century, Einstein dared to "deny" the development of a very perfect light electromagnetic theory, so that the quantum of light can be developed. In 1924, De Broglie put forward wave-particle duality if light to other micro particles and the concept of matter wave, pointed out that all micro particle has wave-particle duality. This is a very abstract concept for students, most college physics teaching all lack of demonstration about particle duality of light. The present article aims to contribute to demonstrate the wave-particle duality of light at the same time using a simple way based on fiber optical tweezers. It is hoped that useful lesson can be absorbed so that students can deepen the understanding of the particle and wave properties of light. To complement the demonstration experiment for this attribute light has momentum.

Majorana modes in solid state systems and its dynamics

NASA Astrophysics Data System (ADS)

Zhang, Qi; Wu, Biao

2018-04-01

We review the properties of Majorana fermions in particle physics and point out that Majorana modes in solid state systems are significantly different. The key reason is the concept of anti-particle in solid state systems is different from its counterpart in particle physics. We define Majorana modes as the eigenstates of Majorana operators and find that they can exist both at edges and in the bulk. According to our definition, only one single Majorana mode can exist in a system no matter at edges or in the bulk. Kitaev's spinless p-wave superconductor is used to illustrate our results and the dynamical behavior of the Majorana modes.

Collisions of unequal mass black holes and the point particle limit

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

Sperhake, Ulrich; CENTRA, Departamento de Fisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa - UTL, Av. Rovisco Pais 1, 1049 Lisboa; California Institute of Technology, Pasadena, California 91125

Numerical relativity has seen incredible progress in the last years, and is being applied with success to a variety of physical phenomena, from gravitational wave research and relativistic astrophysics to cosmology and high-energy physics. Here we probe the limits of current numerical setups, by studying collisions of unequal mass, nonrotating black holes of mass ratios up to 1 ratio 100 and making contact with a classical calculation in general relativity: the infall of a pointlike particle into a massive black hole. Our results agree well with the predictions coming from linearized calculations of the infall of pointlike particles into nonrotatingmore » black holes. In particular, in the limit that one hole is much smaller than the other, and the infall starts from an infinite initial separation, we recover the point-particle limit. Thus, numerical relativity is able to bridge the gap between fully nonlinear dynamics and linearized approximations, which may have important applications. Finally, we also comment on the 'spurious' radiation content in the initial data and the linearized predictions.« less

Particle Dark Matter constraints: the effect of Galactic uncertainties

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

Benito, Maria; Bernal, Nicolás; Iocco, Fabio

2017-02-01

Collider, space, and Earth based experiments are now able to probe several extensions of the Standard Model of particle physics which provide viable dark matter candidates. Direct and indirect dark matter searches rely on inputs of astrophysical nature, such as the local dark matter density or the shape of the dark matter density profile in the target in object. The determination of these quantities is highly affected by astrophysical uncertainties. The latter, especially those for our own Galaxy, are ill-known, and often not fully accounted for when analyzing the phenomenology of particle physics models. In this paper we present amore » systematic, quantitative estimate of how astrophysical uncertainties on Galactic quantities (such as the local galactocentric distance, circular velocity, or the morphology of the stellar disk and bulge) propagate to the determination of the phenomenology of particle physics models, thus eventually affecting the determination of new physics parameters. We present results in the context of two specific extensions of the Standard Model (the Singlet Scalar and the Inert Doublet) that we adopt as case studies for their simplicity in illustrating the magnitude and impact of such uncertainties on the parameter space of the particle physics model itself. Our findings point toward very relevant effects of current Galactic uncertainties on the determination of particle physics parameters, and urge a systematic estimate of such uncertainties in more complex scenarios, in order to achieve constraints on the determination of new physics that realistically include all known uncertainties.« less

The Creative Power of Formal Analogies in Physics: The Case of Albert Einstein

NASA Astrophysics Data System (ADS)

Gingras, Yves

2015-07-01

In order to show how formal analogies between different physical systems play an important conceptual work in physics, this paper analyzes the evolution of Einstein's thoughts on the structure of radiation from the point of view of the formal analogies he used as "lenses" to "see" through the "black box" of Planck's blackbody radiation law. A comparison is also made with his 1925 paper on the quantum gas where he used the same formal methods. Changes of formal points of view are most of the time taken for granted or passed over in silence in studies on the mathematization of physics as if they had no special significance. Revisiting Einstein's classic papers on the nature of light and matter from the angle of the various theoretical tools he used, namely entropy and energy fluctuation calculations, helps explain why he was in a unique position to make visible the particle structure of radiation and the dual (particle and wave) nature of light and matter. Finally, this case study calls attention to the more general question of the surprising creative power of formal analogies and their frequent use in theoretical physics. This aspect of intellectual creation can be useful in the teaching of physics.

On the spatial coordinate measurement of two identical particles

NASA Astrophysics Data System (ADS)

Marchewka, Avi; Granot, Er'el; Schuss, Zeev

2016-04-01

Theoretically, the coordinate measurement of two identical particles at a point by two narrowly separated narrow detectors, is interpreted in the limit of shrinking width and separation, as the detection of two particles by a single narrow detector. Ordinarily, the ratio between probabilities of point measurements is independent of the width of the narrow detectors. We show here that not only this is not the case, but that in some scenarios the results depend on the way the dimensions shrink to zero. The ratio between the width and the separation determines the detection result. In particular, it is shown that the bunching parameter of bosons is not a well-defined physical property. Moreover, it may suggests that there is a difficulty in quantum measurement theory in the interpretation of coordinate measurement of two particles.

Standard map in magnetized relativistic systems: fixed points and regular acceleration.

PubMed

de Sousa, M C; Steffens, F M; Pakter, R; Rizzato, F B

2010-08-01

We investigate the concept of a standard map for the interaction of relativistic particles and electrostatic waves of arbitrary amplitudes, under the action of external magnetic fields. The map is adequate for physical settings where waves and particles interact impulsively, and allows for a series of analytical result to be exactly obtained. Unlike the traditional form of the standard map, the present map is nonlinear in the wave amplitude and displays a series of peculiar properties. Among these properties we discuss the relation involving fixed points of the maps and accelerator regimes.

‘Rutherford’s experiment’ on alpha particles scattering: the experiment that never was

NASA Astrophysics Data System (ADS)

Leone, M.; Robotti, N.; Verna, G.

2018-05-01

The so-called Rutherford’s experiment, as it is outlined in many physics textbooks, is a case in point of the flaws around the history at the educational level of one of the decisive event of modern physics: the discovery that the atom has a nucleus. This paper shows that this alleged experiment is a very approximate and very partial synthesis of a series of different particle scattering experiments, starting with that carried out by Rutherford in 1906 and ending with Geiger and Marsden’s 1913 experiments.

Weyl Points in Three-Dimensional Optical Lattices: Synthetic Magnetic Monopoles in Momentum Space.

PubMed

Dubček, Tena; Kennedy, Colin J; Lu, Ling; Ketterle, Wolfgang; Soljačić, Marin; Buljan, Hrvoje

2015-06-05

We show that a Hamiltonian with Weyl points can be realized for ultracold atoms using laser-assisted tunneling in three-dimensional optical lattices. Weyl points are synthetic magnetic monopoles that exhibit a robust, three-dimensional linear dispersion, identical to the energy-momentum relation for relativistic Weyl fermions, which are not yet discovered in particle physics. Weyl semimetals are a promising new avenue in condensed matter physics due to their unusual properties such as the topologically protected "Fermi arc" surface states. However, experiments on Weyl points are highly elusive. We show that this elusive goal is well within experimental reach with an extension of techniques recently used in ultracold gases.

What Is Light?. Students' Reflections on the Wave-Particle Duality of Light and the Nature of Physics

NASA Astrophysics Data System (ADS)

Henriksen, Ellen Karoline; Angell, Carl; Vistnes, Arnt Inge; Bungum, Berit

2018-03-01

Quantum physics describes light as having both particle and wave properties; however, there is no consensus about how to interpret this duality on an ontological level. This article explores how pre-university physics students, while working with learning material focusing on historical-philosophical aspects of quantum physics, interpreted the wave-particle duality of light and which views they expressed on the nature of physics. A thematic analysis was performed on 133 written responses about the nature of light, given in the beginning of the teaching sequence, and 55 audio-recorded small-group discussions addressing the wave-particle duality, given later in the sequence. Most students initially expressed a wave and particle view of light, but some of these gave an "uncritical duality description", accepting without question the two ontologically different descriptions of light. In the small-group discussions, students expressed more nuanced views. Many tried to reconcile the two descriptions using semi-classical reasoning; others entered into philosophical discussions about the status of the current scientific description of light and expected science to come up with a better model. Some found the wave description of light particularly challenging and lacked a conception of "what is waving". Many seemed to implicitly take a realist view on the description of physical phenomena, contrary with the Copenhagen interpretation which is prevalent in textbooks. Results are discussed in light of different interpretations of quantum physics, and we conclude by arguing for a historical-philosophical perspective as an entry point for upper secondary physics students to explore the development and interpretation of quantum physical concepts.

Fast Inference of Deep Neural Networks in FPGAs for Particle Physics

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

Duarte, Javier; Han, Song; Harris, Philip

Recent results at the Large Hadron Collider (LHC) have pointed to enhanced physics capabilities through the improvement of the real-time event processing techniques. Machine learning methods are ubiquitous and have proven to be very powerful in LHC physics, and particle physics as a whole. However, exploration of the use of such techniques in low-latency, low-power FPGA hardware has only just begun. FPGA-based trigger and data acquisition (DAQ) systems have extremely low, sub-microsecond latency requirements that are unique to particle physics. We present a case study for neural network inference in FPGAs focusing on a classifier for jet substructure which wouldmore » enable, among many other physics scenarios, searches for new dark sector particles and novel measurements of the Higgs boson. While we focus on a specific example, the lessons are far-reaching. We develop a package based on High-Level Synthesis (HLS) called hls4ml to build machine learning models in FPGAs. The use of HLS increases accessibility across a broad user community and allows for a drastic decrease in firmware development time. We map out FPGA resource usage and latency versus neural network hyperparameters to identify the problems in particle physics that would benefit from performing neural network inference with FPGAs. For our example jet substructure model, we fit well within the available resources of modern FPGAs with a latency on the scale of 100 ns.« less

Physical scales in the Wigner-Boltzmann equation

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

Nedjalkov, M., E-mail: mixi@iue.tuwien.ac.at; Selberherr, S.; Ferry, D.K.

2013-01-15

The Wigner-Boltzmann equation provides the Wigner single particle theory with interactions with bosonic degrees of freedom associated with harmonic oscillators, such as phonons in solids. Quantum evolution is an interplay of two transport modes, corresponding to the common coherent particle-potential processes, or to the decoherence causing scattering due to the oscillators. Which evolution mode will dominate depends on the scales of the involved physical quantities. A dimensionless formulation of the Wigner-Boltzmann equation is obtained, where these scales appear as dimensionless strength parameters. A notion called scaling theorem is derived, linking the strength parameters to the coupling with the oscillators. Itmore » is shown that an increase of this coupling is equivalent to a reduction of both the strength of the electric potential, and the coherence length. Secondly, the existence of classes of physically different, but mathematically equivalent setups of the Wigner-Boltzmann evolution is demonstrated. - Highlights: Black-Right-Pointing-Pointer Dimensionless parameters determine the ratio of quantum or classical WB evolution. Black-Right-Pointing-Pointer The scaling theorem evaluates the decoherence effect due to scattering. Black-Right-Pointing-Pointer Evolution processes are grouped into classes of equivalence.« less

Binary Colloidal Alloy Test-3 and 4: Critical Point

NASA Technical Reports Server (NTRS)

Weitz, David A.; Lu, Peter J.

2007-01-01

Binary Colloidal Alloy Test - 3 and 4: Critical Point (BCAT-3-4-CP) will determine phase separation rates and add needed points to the phase diagram of a model critical fluid system. Crewmembers photograph samples of polymer and colloidal particles (tiny nanoscale spheres suspended in liquid) that model liquid/gas phase changes. Results will help scientists develop fundamental physics concepts previously cloaked by the effects of gravity.

Physical characteristics of cometary dust from dynamical studies - A review

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1980-01-01

Progress made in the determination of the physical characteristics of cometary dust particles from studies of dust tail dynamics is reviewed. Applications of the combined dynamical photometric approach of Finson and Probstein (1968) to studies of cometary tails exhibiting continuous light intensity variations are discussed, with attention given to determinations of the particle-size-related distribution function of the solar radiation pressure exerted on the particles, the contribution of comets to the interplanetary dust, calculations of dust ejection rates and a Monte Carlo approach to the analysis of dust tails. Investigations of dust streamers and striae, which are believed to be related to comet outbursts entailing brief but sharp enhancements of dust production, are then reviewed, with particular attention given to observations of Comet West 1976 VI. Finally, the question of cometary particle type is addressed, and it is pointed out that the presence of submicron absorbing particles in the striae of Comet West is not incompatible with the presence of micron-size dielectric particles in the inner coma.

Communication: translational Brownian motion for particles of arbitrary shape.

PubMed

Cichocki, Bogdan; Ekiel-Jeżewska, Maria L; Wajnryb, Eligiusz

2012-02-21

A single Brownian particle of arbitrary shape is considered. The time-dependent translational mean square displacement W(t) of a reference point at this particle is evaluated from the Smoluchowski equation. It is shown that at times larger than the characteristic time scale of the rotational Brownian relaxation, the slope of W(t) becomes independent of the choice of a reference point. Moreover, it is proved that in the long-time limit, the slope of W(t) is determined uniquely by the trace of the translational-translational mobility matrix μ(tt) evaluated with respect to the hydrodynamic center of mobility. The result is applicable to dynamic light scattering measurements, which indeed are performed in the long-time limit. © 2012 American Institute of Physics

Effects of translation-rotation coupling on the displacement probability distribution functions of boomerang colloidal particles

NASA Astrophysics Data System (ADS)

Chakrabarty, Ayan; Wang, Feng; Sun, Kai; Wei, Qi-Huo

Prior studies have shown that low symmetry particles such as micro-boomerangs exhibit behaviour of Brownian motion rather different from that of high symmetry particles because convenient tracking points (TPs) are usually inconsistent with the center of hydrodynamic stress (CoH) where the translational and rotational motions are decoupled. In this paper we study the effects of the translation-rotation coupling on the displacement probability distribution functions (PDFs) of the boomerang colloid particles with symmetric arms. By tracking the motions of different points on the particle symmetry axis, we show that as the distance between the TP and the CoH is increased, the effects of translation-rotation coupling becomes pronounced, making the short-time 2D PDF for fixed initial orientation to change from elliptical to crescent shape and the angle averaged PDFs from ellipsoidal-particle-like PDF to a shape with a Gaussian top and long displacement tails. We also observed that at long times the PDFs revert to Gaussian. This crescent shape of 2D PDF provides a clear physical picture of the non-zero mean displacements observed in boomerangs particles.

Flow induced crystallisation of penetrable particles

NASA Astrophysics Data System (ADS)

Scacchi, Alberto; Brader, Joseph M.

2018-03-01

For a system of Brownian particles interacting via a soft exponential potential we investigate the interaction between equilibrium crystallisation and spatially varying shear flow. For thermodynamic state points within the liquid part of the phase diagram, but close to the crystallisation phase boundary, we observe that imposing a Poiseuille flow can induce nonequilibrium crystalline ordering in regions of low shear gradient. The physical mechanism responsible for this phenomenon is shear-induced particle migration, which causes particles to drift preferentially towards the center of the flow channel, thus increasing the local density in the channel center. The method employed is classical dynamical density functional theory.

Flow induced crystallisation of penetrable particles.

PubMed

Scacchi, Alberto; Brader, Joseph M

2018-03-07

For a system of Brownian particles interacting via a soft exponential potential we investigate the interaction between equilibrium crystallisation and spatially varying shear flow. For thermodynamic state points within the liquid part of the phase diagram, but close to the crystallisation phase boundary, we observe that imposing a Poiseuille flow can induce nonequilibrium crystalline ordering in regions of low shear gradient. The physical mechanism responsible for this phenomenon is shear-induced particle migration, which causes particles to drift preferentially towards the center of the flow channel, thus increasing the local density in the channel center. The method employed is classical dynamical density functional theory.

Melt Adsorption as a Manufacturing Method for Fine Particles of Wax Matrices without Any Agglomerates.

PubMed

Shiino, Kai; Fujinami, Yukari; Kimura, Shin-Ichiro; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

2017-01-01

We have focused on melt adsorption as manufacture method of wax matrices to control particles size of granules more easily than melt granulation. The purpose of present study was to investigate the possibility of identifying a hydrophobic material with a low melting point, currently used as a meltable binder of melt granulation, to apply as a novel carrier in melt adsorption. Glyceryl monostearate (GM) and stearic acid (SA) were selected as candidate hydrophobic materials with low melting points. Neusilin US2 (US2), with a particle diameter of around 100 µm was selected as a surface adsorbent, while dibasic calcium phosphate dihydrate (DCPD), was used as a non-adsorbent control to prepare melting granules as a standard for comparison. We prepared granules containing ibuprofen (IBU) by melt adsorption or melt granulation and evaluated the particle size, physical properties and crystallinity of granules. Compared with melt granulation using DCPD, melt adsorption can be performed over a wide range of 14 to 70% for the ratio of molten components. Moreover, the particle size; d50 of obtained granules was 100-200 µm, and these physical properties showed good flowability and roundness. The process of melt adsorption did not affect the crystalline form of IBU. Therefore, the present study has demonstrated for the first time that melt adsorption using a hydrophobic material, GM or SA, has the potential capability to control the particle size of granules and offers the possibility of application as a novel controlled release technique.

Physics of the saturation of particle acceleration in relativistic magnetic reconnection

NASA Astrophysics Data System (ADS)

Kagan, Daniel; Nakar, Ehud; Piran, Tsvi

2018-05-01

We investigate the saturation of particle acceleration in relativistic reconnection using two-dimensional particle-in-cell simulations at various magnetizations σ. We find that the particle energy spectrum produced in reconnection quickly saturates as a hard power law that cuts off at γ ≈ 4σ, confirming previous work. Using particle tracing, we find that particle acceleration by the reconnection electric field in X-points determines the shape of the particle energy spectrum. By analysing the current sheet structure, we show that physical cause of saturation is the spontaneous formation of secondary magnetic islands that can disrupt particle acceleration. By comparing the size of acceleration regions to the typical distance between disruptive islands, we show that the maximum Lorentz factor produced in reconnection is γ ≈ 5σ, which is very close to what we find in our particle energy spectra. We also show that the dynamic range in Lorentz factor of the power-law spectrum in reconnection is ≤40. The hardness of the power law combined with its narrow dynamic range implies that relativistic reconnection is capable of producing the hard narrow-band flares observed in the Crab nebula but has difficulty producing the softer broad-band prompt gamma-ray burst emission.

Load management strategy for Particle-In-Cell simulations in high energy particle acceleration

NASA Astrophysics Data System (ADS)

Beck, A.; Frederiksen, J. T.; Dérouillat, J.

2016-09-01

In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight into the fundamental physics at play. As a by-product, they also characterize the quality of our theoretical and numerical models. In this paper, we compare the results given by different codes and point out algorithmic limitations both in terms of physical accuracy and computational performances. These limitations are illustrated in the context of electron laser wakefield acceleration (LWFA). The main limitation we identify in state-of-the-art Particle-In-Cell (PIC) codes is computational load imbalance. We propose an innovative algorithm to deal with this specific issue as well as milestones towards a modern, accurate high-performance PIC code for high energy particle acceleration.

Particle physics catalysis of thermal big bang nucleosynthesis.

PubMed

Pospelov, Maxim

2007-06-08

We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.

Spectro-microscopic Characterization of Physical Properties and Phase Separations in Individual Atmospheric Particles

NASA Astrophysics Data System (ADS)

OBrien, R. E.; Wang, B.; Neu, A.; Kelly, S. T.; Lundt, N.; Epstein, S. A.; MacMillan, A.; You, Y.; Laskin, A.; Nizkorodov, S.; Bertram, A. K.; Moffet, R.; Gilles, M.

2013-12-01

The phase state and liquid-liquid phase separations of ambient and laboratory generated aerosol particles were investigated using (1) scanning transmission x-ray microscopy/near-edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS) coupled to a relative humidity (RH) controlled in-situ chamber and (2) environmental scanning electron microscopy (ESEM). The phase states of the particles were determined from measurements of their size and optical density. A comparison is made between the observed phase states of ambient samples and of laboratory generated aerosols to determine how well laboratory samples represent the phase of ambient samples. In addition, liquid-liquid phase separations in laboratory generated particles were investigated. Preliminary results showing that liquid-liquid phase separations occur at RH's between the deliquescence and efflorescence points and that the organic phase surrounds the inorganic phase will be presented. The STXM/NEXAFS technique provides insight into the degree of mixing at the deliquescence point and the degree of phase separation for particles of atmospherically relevant sizes.

Probing new physics with long-lived charged particles produced by atmospheric and astrophysical neutrinos

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

Ando, Shin'ichiro; Profumo, Stefano; Beacom, John F

As suggested by some extensions of the standard model of particle physics, dark matter may be a super-weakly-interacting lightest stable particle, while the next-to-lightest particle (NLP) is charged and metastable. One could test such a possibility with neutrino telescopes, by detecting the charged NLPs produced in high-energy neutrino collisions with Earth matter. We study the production of charged NLPs by both atmospheric and astrophysical neutrinos; only the latter, which is largely uncertain and has not been detected yet, was the focus of previous studies. We compute the resulting fluxes of the charged NLPs, compare those of different origins and analyzemore » the dependence on the underlying particle physics set-up. We point out that, even if the astrophysical neutrino flux is very small, atmospheric neutrinos, especially those from the prompt decay of charmed mesons, may provide a detectable flux of NLP pairs at neutrino telescopes such as IceCube. We also comment on the flux of charged NLPs expected from proton-nucleon collisions and show that, for theoretically motivated and phenomenologically viable models, it is typically subdominant and below detectable rates.« less

The SHIP facility at CERN

NASA Astrophysics Data System (ADS)

De Lellis, Giovanni

2016-04-01

Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. A new experimental facility meant to search for very weakly coupled particles in the few GeV mass domain has been recently proposed. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. In particular, tau anti-neutrinos have not been directly observed so far. We report the physics potential of such an experiment and outline the performances of a detector operating at the same facility for the search for the τ → μμμ decay.

A centroid molecular dynamics study of liquid para-hydrogen and ortho-deuterium.

PubMed

Hone, Tyler D; Voth, Gregory A

2004-10-01

Centroid molecular dynamics (CMD) is applied to the study of collective and single-particle dynamics in liquid para-hydrogen at two state points and liquid ortho-deuterium at one state point. The CMD results are compared with the results of classical molecular dynamics, quantum mode coupling theory, a maximum entropy analytic continuation approach, pair-product forward- backward semiclassical dynamics, and available experimental results. The self-diffusion constants are in excellent agreement with the experimental measurements for all systems studied. Furthermore, it is shown that the method is able to adequately describe both the single-particle and collective dynamics of quantum liquids. (c) 2004 American Institute of Physics

Point-particle method to compute diffusion-limited cellular uptake.

PubMed

Sozza, A; Piazza, F; Cencini, M; De Lillo, F; Boffetta, G

2018-02-01

We present an efficient point-particle approach to simulate reaction-diffusion processes of spherical absorbing particles in the diffusion-limited regime, as simple models of cellular uptake. The exact solution for a single absorber is used to calibrate the method, linking the numerical parameters to the physical particle radius and uptake rate. We study the configurations of multiple absorbers of increasing complexity to examine the performance of the method by comparing our simulations with available exact analytical or numerical results. We demonstrate the potential of the method to resolve the complex diffusive interactions, here quantified by the Sherwood number, measuring the uptake rate in terms of that of isolated absorbers. We implement the method in a pseudospectral solver that can be generalized to include fluid motion and fluid-particle interactions. As a test case of the presence of a flow, we consider the uptake rate by a particle in a linear shear flow. Overall, our method represents a powerful and flexible computational tool that can be employed to investigate many complex situations in biology, chemistry, and related sciences.

Using Field-Particle Correlations to Diagnose the Collisionless Damping of Plasma Turbulence

NASA Astrophysics Data System (ADS)

Howes, Gregory; Klein, Kristropher

2016-10-01

Plasma turbulence occurs ubiquitously throughout the heliosphere, yet our understanding of how turbulence governs energy transport and plasma heating remains incomplete, constituting a grand challenge problem in heliophysics. In weakly collisional heliospheric plasmas, such as the solar corona and solar wind, damping of the turbulent fluctuations occurs due to collisionless interactions between the electromagnetic fields and the individual plasma particles. A particular challenge in diagnosing this energy transfer is that spacecraft measurements are typically limited to a single point in space. Here we present an innovative field-particle correlation technique that can be used with single-point measurements to estimate the energization of the plasma particles due to the damping of the electromagnetic fields, providing vital new information about this how energy transfer is distributed as a function of particle velocity. This technique has the promise to transform our ability to diagnose the kinetic plasma physical mechanisms responsible for not only the damping of turbulence, but also the energy conversion in both collisionless magnetic reconnection and particle acceleration. The work has been supported by NSF CAREER Award AGS-1054061, NSF AGS-1331355, and DOE DE-SC0014599.

Identifying microturbulence regimes in a TCV discharge making use of physical constraints on particle and heat fluxes

DOE PAGES

Mariani, Alberto; Brunner, S.; Dominski, J.; ...

2018-01-17

Reducing the uncertainty on physical input parameters derived from experimental measurements is essential towards improving the reliability of gyrokinetic turbulence simulations. This can be achieved by introducing physical constraints. Amongst them, the zero particle flux condition is considered here. A first attempt is also made to match as well the experimental ion/electron heat flux ratio. This procedure is applied to the analysis of a particular Tokamak à Configuration Variable discharge. A detailed reconstruction of the zero particle flux hyper-surface in the multi-dimensional physical parameter space at fixed time of the discharge is presented, including the effect of carbon as themore » main impurity. Both collisionless and collisional regimes are considered. Hyper-surface points within the experimental error bars are found. In conclusion, the analysis is done performing gyrokinetic simulations with the local version of the GENE code, computing the fluxes with a Quasi-Linear (QL) model and validating the QL results with non-linear simulations in a subset of cases.« less

Identifying microturbulence regimes in a TCV discharge making use of physical constraints on particle and heat fluxes

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

Mariani, Alberto; Brunner, S.; Dominski, J.

Reducing the uncertainty on physical input parameters derived from experimental measurements is essential towards improving the reliability of gyrokinetic turbulence simulations. This can be achieved by introducing physical constraints. Amongst them, the zero particle flux condition is considered here. A first attempt is also made to match as well the experimental ion/electron heat flux ratio. This procedure is applied to the analysis of a particular Tokamak à Configuration Variable discharge. A detailed reconstruction of the zero particle flux hyper-surface in the multi-dimensional physical parameter space at fixed time of the discharge is presented, including the effect of carbon as themore » main impurity. Both collisionless and collisional regimes are considered. Hyper-surface points within the experimental error bars are found. In conclusion, the analysis is done performing gyrokinetic simulations with the local version of the GENE code, computing the fluxes with a Quasi-Linear (QL) model and validating the QL results with non-linear simulations in a subset of cases.« less

Thermodynamics sheds light on black hole dynamics

NASA Astrophysics Data System (ADS)

Cárdenas, Marcela; Julié, Félix-Louis; Deruelle, Nathalie

2018-06-01

We propose to unify two a priori distinct aspects of black hole physics: their thermodynamics, and their description as point particles, which is an essential starting point in the post-Newtonian approach to their dynamics. We will find that, when reducing a black hole to a point particle endowed with its specific effective mass, one in fact describes a black hole satisfying the first law of thermodynamics, such that its global charges, and hence its entropy, remain constant. This gives a thermodynamical interpretation of its effective mass, thus opening a promising synergy between black hole thermodynamics and the analytical approaches to the two-body problems in gravity theories. To illustrate this relationship, the Einstein-Maxwell-dilaton theory, which contains simple examples of asympotically flat, hairy black hole solutions, will serve as a laboratory.

"Rutherford's Experiment" on Alpha Particles Scattering: The Experiment That Never Was

ERIC Educational Resources Information Center

Leone, M.; Robotti, N.; Verna, G.

2018-01-01

The so-called "Rutherford's experiment," as it is outlined in many physics textbooks, is a case in point of the flaws around the history at the educational level of one of the decisive event of modern physics: the discovery that the atom has a nucleus. This paper shows that this alleged experiment is a very approximate and very partial…

Physical properties of elongated magnetic particles: magnetization and friction coefficient anisotropies.

PubMed

Vereda, Fernando; de Vicente, Juan; Hidalgo-Alvarez, Roque

2009-06-02

Anisotropy counts: A brief review of the main physical properties of elongated magnetic particles (EMPs) is presented. The most important characteristic of an EMP is the additional contribution of shape anisotropy to the total anisotropy energy of the particle, when compared to spherical magnetic particles. The electron micrograph shows Ni-ferrite microrods fabricated by the authors.We present an overview of the main physical properties of elongated magnetic particles (EMPs), including some of their more relevant properties in suspension. When compared to a spherical magnetic particle, the most important characteristic of an EMP is an additional contribution of shape anisotropy to the total anisotropy energy of the particle. Increasing aspect ratios also lead to an increase in both the critical single-domain size of a magnetic particle and its resistance to thermally activated spontaneous reversal of the magnetization. For single-domain EMPs, magnetization reversal occurs primarily by one of two modes, coherent rotation or curling, the latter being facilitated by larger aspect ratios. When EMPs are used to prepare colloidal suspensions, other physical properties come into play, such as their anisotropic friction coefficient and the consequent enhanced torque they experience in a shear flow, their tendency to align in the direction of an external field, to form less dense sediments and to entangle into more intricate aggregates. From a more practical point of view, EMPs are discussed in connection with two interesting types of magnetic colloids: magnetorheological fluids and suspensions for magnetic hyperthermia. Advances reported in the literature regarding the use of EMPs in these two systems are included. In the final section, we present a summary of the most relevant methods documented in the literature for the fabrication of EMPs, together with a list of the most common ferromagnetic materials that have been synthesized in the form of EMPs.

Proceedings of the Quantum Computation for Physical Modeling Workshop Held in North Falmouth, Massachusetts on October 18-19, 2000

DTIC Science & Technology

2002-01-01

1-3], a task that is exponen- algorithms to model quantum mechanical systems. tially complex in the number of particles treated and A starting point ...cell size approaches zero). There- tion were presented by Succi and Benzi [10,11] and fore, from the point -of-view of the modeler, there ex- by... point regarding this particular In both cases, the model behaves as expected. gate is that when measurements are periodically made Third, in Section 4

Effects of translation-rotation coupling on the displacement probability distribution functions of boomerang colloidal particles.

PubMed

Chakrabarty, Ayan; Wang, Feng; Sun, Kai; Wei, Qi-Huo

2016-05-11

Prior studies have shown that low symmetry particles such as micro-boomerangs exhibit behaviour of Brownian motion rather different from that of high symmetry particles because convenient tracking points (TPs) are usually inconsistent with their center of hydrodynamic stress (CoH) where the translational and rotational motions are decoupled. In this paper we study the effects of the translation-rotation coupling on the displacement probability distribution functions (PDFs) of the boomerang colloid particles with symmetric arm length. By tracking the motions of different points on the particle symmetry axis, we show that as the distance between the TP and the CoH is increased, the effects of translation-rotation coupling becomes pronounced, making the short-time 2D PDF for fixed initial orientation to change from elliptical, to bean and then to crescent shape, and the angle averaged PDFs change from ellipsoidal-particle-like PDF to a shape with a Gaussian top and long displacement tails. We also observed that at long times the PDFs revert to Gaussian. These 2D PDF shapes provide a clear physical picture of the non-zero mean displacements observed in boomerangs particles.

The long journey to the Higgs boson and beyond at the LHC: Emphasis on CMS

NASA Astrophysics Data System (ADS)

Virdee, Tejinder Singh

2016-11-01

Since 2010 there has been a rich harvest of results on standard model physics by the ATLAS and CMS experiments operating on the Large Hadron Collider. In the summer of 2012, a spectacular discovery was made by these experiments of a new, heavy particle. All the subsequently analysed data point strongly to the properties of this particle as those expected for the Higgs boson associated with the Brout-Englert-Higgs mechanism postulated to explain the spontaneous symmetry breaking in the electroweak sector, thereby explaining how elementary particles acquire mass. This article focuses on the CMS experiment, the technological challenges encountered in its construction, describing some of the physics results obtained so far, including the discovery of the Higgs boson, and searches for the widely anticipated new physics beyond the standard model, and peer into the future involving the high-luminosity phase of the LHC. This article is complementary to the one by Peter Jenni4 that focuses on the ATLAS experiment.

Effects of the Physical Characteristics of Cerium Oxide on Plasma-Enhanced Tetraethylorthosiliate Removal Rate of Chemical Mechanical Polishing for Shallow Trench Isolation

NASA Astrophysics Data System (ADS)

Kim, Sang-Kyun; Paik, Ungyu; Oh, Seong-Geun; Park, Yong-Kook; Katoh, Takeo; Park, Jea-Gun

2003-03-01

Ceria powders were synthesized by two different methods, solid-state displacement reaction and wet chemical precipitation, and the influence of the physical characteristics of cerium oxide on the removal rate of plasma-enhanced tetraethylorthosilicate (PETEOS) and chemical vapor deposition (CVD) nitride films in chemical mechanical planarization (CMP) was investigated. The fundamental physicochemical property and electrokinetic behavior of ceria particles in aqueous suspending media were investigated to identify the correlation between the colloidal property of ceria and the CMP performance. The surface potentials of two different ceria particles are found to have different isoelectric point (pHiep) values and differences in physical properties of ceria particles such as porosity and density were found to be the key parameters in CMP of PETEOS films. Ceria powders synthesized by the solid-state displacement reaction method yielded a higher removal rate of PETEOS and higher selectivity than powders synthesized by the wet chemical precipitation method.

The pdf approach to turbulent polydispersed two-phase flows

NASA Astrophysics Data System (ADS)

Minier, Jean-Pierre; Peirano, Eric

2001-10-01

The purpose of this paper is to develop a probabilistic approach to turbulent polydispersed two-phase flows. The two-phase flows considered are composed of a continuous phase, which is a turbulent fluid, and a dispersed phase, which represents an ensemble of discrete particles (solid particles, droplets or bubbles). Gathering the difficulties of turbulent flows and of particle motion, the challenge is to work out a general modelling approach that meets three requirements: to treat accurately the physically relevant phenomena, to provide enough information to address issues of complex physics (combustion, polydispersed particle flows, …) and to remain tractable for general non-homogeneous flows. The present probabilistic approach models the statistical dynamics of the system and consists in simulating the joint probability density function (pdf) of a number of fluid and discrete particle properties. A new point is that both the fluid and the particles are included in the pdf description. The derivation of the joint pdf model for the fluid and for the discrete particles is worked out in several steps. The mathematical properties of stochastic processes are first recalled. The various hierarchies of pdf descriptions are detailed and the physical principles that are used in the construction of the models are explained. The Lagrangian one-particle probabilistic description is developed first for the fluid alone, then for the discrete particles and finally for the joint fluid and particle turbulent systems. In the case of the probabilistic description for the fluid alone or for the discrete particles alone, numerical computations are presented and discussed to illustrate how the method works in practice and the kind of information that can be extracted from it. Comments on the current modelling state and propositions for future investigations which try to link the present work with other ideas in physics are made at the end of the paper.

Analysis of angle effect on particle flocculation in branch flow

NASA Astrophysics Data System (ADS)

Prasad, Karthik; Fink, Kathryn; Liepmann, Dorian

2014-11-01

Hollow point microneedle drug delivery systems are known to be highly susceptible to blockage, owing to their very small structures. This problem has been especially noted when delivering suspended particle solutions, such as vaccines. Attempts to reduce particle flocculation in such devices through surface treatments of the particles have been largely unsuccessful. Furthermore, the particle clog only forms at the mouths of the microneedle structures, leaving the downstream walls clear. This implies that the sudden change in length scales alter the hydrodynamic interactions, creating the conditions for particle flocculation. However, while it is known that particle flocculation occurs, the physics behind the event are obscure. We utilize micro-PIV to observe how the occurrence and formation of particle flocculation changes in relation to the angle encountered by particle laden flow into microfluidic branch structures. The results offer the ability to optimize particle flocculation in MEMS devices, increasing device efficacy and longevity.

Hybrid immersed interface-immersed boundary methods for AC dielectrophoresis

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

Hossan, Mohammad Robiul; Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034-5209; Dillon, Robert

2014-08-01

Dielectrophoresis, a nonlinear electrokinetic transport mechanism, has become popular in many engineering applications including manipulation, characterization and actuation of biomaterials, particles and biological cells. In this paper, we present a hybrid immersed interface–immersed boundary method to study AC dielectrophoresis where an algorithm is developed to solve the complex Poisson equation using a real variable formulation. An immersed interface method is employed to obtain the AC electric field in a fluid media with suspended particles and an immersed boundary method is used for the fluid equations and particle transport. The convergence of the proposed algorithm as well as validation of themore » hybrid scheme with experimental results is presented. In this paper, the Maxwell stress tensor is used to calculate the dielectrophoretic force acting on particles by considering the physical effect of particles in the computational domain. Thus, this study eliminates the approximations used in point dipole methods for calculating dielectrophoretic force. A comparative study between Maxwell stress tensor and point dipole methods for computing dielectrophoretic forces are presented. The hybrid method is used to investigate the physics of dielectrophoresis in microfluidic devices using an AC electric field. The numerical results show that with proper design and appropriate selection of applied potential and frequency, global electric field minima can be obtained to facilitate multiple particle trapping by exploiting the mechanism of negative dielectrophoresis. Our numerical results also show that electrically neutral particles form a chain parallel to the applied electric field irrespective of their initial orientation when an AC electric field is applied. This proposed hybrid numerical scheme will help to better understand dielectrophoresis and to design and optimize microfluidic devices.« less

Dimension-dependent stimulated radiative interaction of a single electron quantum wavepacket

NASA Astrophysics Data System (ADS)

Gover, Avraham; Pan, Yiming

2018-06-01

In the foundation of quantum mechanics, the spatial dimensions of electron wavepacket are understood only in terms of an expectation value - the probability distribution of the particle location. One can still inquire how the quantum electron wavepacket size affects a physical process. Here we address the fundamental physics problem of particle-wave duality and the measurability of a free electron quantum wavepacket. Our analysis of stimulated radiative interaction of an electron wavepacket, accompanied by numerical computations, reveals two limits. In the quantum regime of long wavepacket size relative to radiation wavelength, one obtains only quantum-recoil multiphoton sidebands in the electron energy spectrum. In the opposite regime, the wavepacket interaction approaches the limit of classical point-particle acceleration. The wavepacket features can be revealed in experiments carried out in the intermediate regime of wavepacket size commensurate with the radiation wavelength.

Search of low-mass WIMPs with a p -type point contact germanium detector in the CDEX-1 experiment

NASA Astrophysics Data System (ADS)

Zhao, W.; Yue, Q.; Kang, K. J.; Cheng, J. P.; Li, Y. J.; Wong, H. T.; Lin, S. T.; Chang, J. P.; Chen, J. H.; Chen, Q. H.; Chen, Y. H.; Deng, Z.; Du, Q.; Gong, H.; Hao, X. Q.; He, H. J.; He, Q. J.; Huang, H. X.; Huang, T. R.; Jiang, H.; Li, H. B.; Li, J.; Li, J.; Li, J. M.; Li, X.; Li, X. Y.; Li, Y. L.; Lin, F. K.; Liu, S. K.; Lü, L. C.; Ma, H.; Ma, J. L.; Mao, S. J.; Qin, J. Q.; Ren, J.; Ren, J.; Ruan, X. C.; Sharma, V.; Shen, M. B.; Singh, L.; Singh, M. K.; Soma, A. K.; Su, J.; Tang, C. J.; Wang, J. M.; Wang, L.; Wang, Q.; Wu, S. Y.; Wu, Y. C.; Xianyu, Z. Z.; Xiao, R. Q.; Xing, H. Y.; Xu, F. Z.; Xu, Y.; Xu, X. J.; Xue, T.; Yang, L. T.; Yang, S. W.; Yi, N.; Yu, C. X.; Yu, H.; Yu, X. Z.; Zeng, M.; Zeng, X. H.; Zeng, Z.; Zhang, L.; Zhang, Y. H.; Zhao, M. G.; Zhou, Z. Y.; Zhu, J. J.; Zhu, W. B.; Zhu, X. Z.; Zhu, Z. H.; CDEX Collaboration

2016-05-01

The CDEX-1 experiment conducted a search of low-mass (<10 GeV /c2 ) weakly interacting massive particles dark matter at the China Jinping Underground Laboratory using a p-type point-contact germanium detector with a fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report the hardware setup, detector characterization, data acquisition, and analysis procedures of this experiment. No excess of unidentified events is observed after the subtraction of the known background. Using 335.6 kg-days of data, exclusion constraints on the weakly interacting massive particle-nucleon spin-independent and spin-dependent couplings are derived.

Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor.

PubMed

Malinowski, Robert; Volpe, Giovanni; Parkin, Ivan P; Volpe, Giorgio

2018-02-01

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner.

Amorphous Silica Micro Powder Additive Influence on Tensile Strength of One-Ply Particle Board

NASA Astrophysics Data System (ADS)

Pitukhin, A. V.; Kolesnikov, G. N.; Panov, N. G.; Vasilyev, S. B.

2018-03-01

The methods and results of experimental investigation on the additive influence of amorphous silica micro powder when mixed in the glue for one-ply particle board are presented in the article. Wooden particles of coniferous and hardwood species as well as glue solution based on carbamide-formaldehyde resin were used for boards manufacturing. The amorphous silica micro powder contained particles on the average 8 μm by the size and specific surface 120…400 m2/g was used in experiment. The samples were tested to determine their physical-mechanical properties. It was found that 1 % amorphous silica micro powder additive increases the breaking point of one-ply particle board under tensile stress by 143 %.

Classical Electrodynamics: Lecture notes

NASA Astrophysics Data System (ADS)

Likharev, Konstantin K.

2018-06-01

Essential Advanced Physics is a series comprising four parts: Classical Mechanics, Classical Electrodynamics, Quantum Mechanics and Statistical Mechanics. Each part consists of two volumes, Lecture notes and Problems with solutions, further supplemented by an additional collection of test problems and solutions available to qualifying university instructors. This volume, Classical Electrodynamics: Lecture notes is intended to be the basis for a two-semester graduate-level course on electricity and magnetism, including not only the interaction and dynamics charged point particles, but also properties of dielectric, conducting, and magnetic media. The course also covers special relativity, including its kinematics and particle-dynamics aspects, and electromagnetic radiation by relativistic particles.

Project X

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

Holmes, Steve; Alber, Russ; Asner, David

2013-06-23

Particle physics has made enormous progress in understanding the nature of matter and forces at a fundamental level and has unlocked many mysteries of our world. The development of the Standard Model of particle physics has been a magnificent achievement of the field. Many deep and important questions have been answered and yet many mysteries remain. The discovery of neutrino oscillations, discrepancies in some precision measurements of Standard-Model processes, observation of matter-antimatter asymmetry, the evidence for the existence of dark matter and dark energy, all point to new physics beyond the Standard Model. The pivotal developments of our field, includingmore » the latest discovery of the Higgs Boson, have progressed within three interlocking frontiers of research – the Energy, Intensity and Cosmic frontiers – where discoveries and insights in one frontier powerfully advance the other frontiers as well.« less

Comparison of 3D ion velocity distribution measurements and models in the vicinity of an absorbing boundary oriented obliquely to a magnetic field

NASA Astrophysics Data System (ADS)

Henriquez, Miguel F.; Thompson, Derek S.; Kenily, Shane; Khaziev, Rinat; Good, Timothy N.; McIlvain, Julianne; Siddiqui, M. Umair; Curreli, Davide; Scime, Earl E.

2016-10-01

Understanding particle distributions in plasma boundary regions is critical to predicting plasma-surface interactions. Ions in the presheath exhibit complex behavior because of collisions and due to the presence of boundary-localized electric fields. Complete understanding of particle dynamics is necessary for understanding the critical problems of tokamak wall loading and Hall thruster channel wall erosion. We report measurements of 3D argon ion velocity distribution functions (IVDFs) in the vicinity of an absorbing boundary oriented obliquely to a background magnetic field. Measurements were obtained via argon ion laser induced fluorescence throughout a spatial volume upstream of the boundary. These distribution functions reveal kinetic details that provide a point-to-point check on particle-in-cell and 1D3V Boltzmann simulations. We present the results of this comparison and discuss some implications for plasma boundary interaction physics.

Measurement of the top quark pair production cross-section in dimuon final states in proton-antiproton collisions at 1.96 TeV

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

Konrath, Jens Peter

2008-10-24

Particle physics deals with the fundamental building blocks of matter and their interactions. The vast number of subatomic particles can be reduced to twelve fundamental fermions, which interact by the exchange of spin-1 particles as described in the Standard Model (SM) of particle physics. The SM provides the best description of the subatomic world to date, despite the fact it does not include gravitation. Following the relation Λ = h/p, where h is Planck's constant, for the examination of physics at subatomic scales with size Λ probes with high momenta p are necessary. These high energies are accessible through particlemore » colliders. Here, particles are accelerated and brought to collision at interaction points at which detectors are installed to record these particle collisions. Until the anticipated start-up of the Large Hadron Collider at CERN, the Tevatron collider at Fermilab near Chicago is the highest energy collider operating in the world, colliding protons and anti-protons at a center-of-mass energy of √s = 1.96 TeV. Its two interaction points are covered by the multi purpose particle detectors D0 and CDF. During the first data-taking period, known as Run I, the Tevatron operated at a center-of-mass energy of 1.8 TeV. This run period lasted from 1992 to 1996. During this period, the long-predicted top quark was discovered. From 1996 and 2001, the accelerator was upgraded to deliver higher instantaneous luminosities at its current center-of-mass energy. At the same time, the experiments were upgraded to take full advantage of the upgraded accelerator complex. The Tevatron is currently the only accelerator in the world with a sufficient energy to produce top quarks. Studying top quark production, decay and properties is an important part of the D0 and CDF physics programs. Because of its large mass, the top quark is a unique probe of the Standard Model, and an interesting environment to search for new physics. In this thesis, a measurement of the production cross-section of top quark pairs decaying to two muons is presented. In addition, a Monte Carlo study of the top quark spin correlation measurement was carried out. This thesis is laid out as follows: chapter two gives a short overview over the Standard Model of particle physics and the theoretical aspects of unpolarized and polarized top quark production and decay, chapter three describes the accelerator complex and the D0 experiment whose data is used in this analysis. The Reconstruction of events recorded with the D0 detector is explained in chapter four and the data and Monte Carlo samples used are presented in chapter five. Finally, the cross-section measurement is described in chapter six and the Monte Carlo study of top quark spin correlations in chapter seven.« less

Research in Theoretical High Energy Physics- Final Report

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

Okada, Nobuchika

PI Dr. Okada’s research interests are centered on phenomenological aspects of particle physics. It has been abundantly clear in recent years that an extension of the Standard Model (SM), i.e. new physics beyond the SM, is needed to explain a number of experimental observations such as the neutrino oscillation data, the existence of non-baryonic dark matter, and the observed baryon asymmetry of the Universe. In addition, the SM suffers from several theoretical/conceptual problems, such as the gauge hierarchy problem, the fermion mass hierarchy problem, and the origin of the electroweak symmetry breaking. It is believed that these problems can alsomore » be solved by new physics beyond the SM. The main purpose of the Dr. Okada’s research is a theoretical investigation of new physics opportunities from various phenomenological points of view, based on the recent progress of experiments/observations in particle physics and cosmology. There are many possibilities to go beyond the SM and many new physics models have been proposed. The major goal of the project is to understand the current status of possible new physics models and obtain the future prospects of new physics phenomena toward their discoveries.« less

The MoEDAL Experiment at the LHC - a New Light on the Terascale Frontier

NASA Astrophysics Data System (ADS)

Pinfold, J. L.

2015-07-01

MoEDAL is a pioneering experiment designed to search for highly ionizing avatars of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; what is the nature of dark matter; and, how did the big-bang develop. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analyzed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL's radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector to extend MoEDAL's reach to millicharged, minimally ionizing, particles (MMIPs) is under study.

How To Prepare Materials With a Desired Refraction Coefficient?

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

Ramm, A. G.

2010-05-21

In this talk a method is described for preparing materials with a desired refraction coefficient. The method consists of embedding into a material with known refraction coefficient many small particles of size a. The number of particles per unit volume around any point is prescribed, the distance between neighboring particles is O(a{sup (2-kappa/3)}) as a->0, 00. The refraction coefficient is themore » coefficient n{sup 2}(x) in the wave equation [nabla{sup 2}+kappa{sup 2}n{sup 2}(x)]u = 0.« less

Laser-driven beam lines for delivering intensity modulated radiation therapy with particle beams

PubMed Central

Hofmann, Kerstin M; Schell, Stefan; Wilkens, Jan J

2012-01-01

Abstract Laser-accelerated particles are a promising option for radiation therapy of cancer by potentially combining a compact, cost-efficient treatment unit with the physical advantages of charged particle beams. To design such a treatment unit we consider different dose delivery schemes and analyze the necessary devices in the required particle beam line for each case. Furthermore, we point out that laser-driven treatment units may be ideal tools for motion adaptation during radiotherapy. Reasons for this are the potential of a flexible gantry and the time structure of the beam with high particle numbers in ultrashort bunches. One challenge that needs to be addressed is the secondary radiation produced in several beam line elements. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) PMID:22930653

Construction of the radiation oncology teaching files system for charged particle radiotherapy.

PubMed

Masami, Mukai; Yutaka, Ando; Yasuo, Okuda; Naoto, Takahashi; Yoshihisa, Yoda; Hiroshi, Tsuji; Tadashi, Kamada

2013-01-01

Our hospital started the charged particle therapy since 1996. New institutions for charged particle therapy are planned in the world. Our hospital are accepting many visitors from those newly planned medical institutions and having many opportunities to provide with the training to them. Based upon our experiences, we have developed the radiation oncology teaching files system for charged particle therapy. We adopted the PowerPoint of Microsoft as a basic framework of our teaching files system. By using our export function of the viewer any physician can create teaching files easily and effectively. Now our teaching file system has 33 cases for clinical and physics contents. We expect that we can improve the safety and accuracy of charged particle therapy by using our teaching files system substantially.

Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor

PubMed Central

2018-01-01

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner. PMID:29363979

Does a String-Particle Dualism Indicate the Uncertainty Principle's Philosophical Dichotomy?

NASA Astrophysics Data System (ADS)

Mc Leod, David; Mc Leod, Roger

2007-04-01

String theory may allow resonances of neutrino-wave-strings to account for all experimentally detected phenomena. Particle theory logically, and physically, provides an alternate, contradictory dualism. Is it contradictory to symbolically and simultaneously state that λp = h, but, the product of position and momentum must be greater than, or equal to, the same (scaled) Plank's constant? Our previous electron and positron models require `membrane' vibrations of string-linked neutrinos, in closed loops, to behave like traveling waves, Tws, intermittently metamorphosing into alternately ascending and descending standing waves, Sws, between the nodes, which advance sequentially through 360 degrees. Accumulated time passages as Tws detail required ``loop currents'' supplying magnetic moments. Remaining time partitions into the Sws' alternately ascending and descending phases: the physical basis of the experimentally established 3D modes of these ``particles.'' Waves seem to indicate that point mass cannot be required to exist instantaneously at one point; Mott's and Sneddon's Wave Mechanics says that a constant, [mass], is present. String-like resonances may also account for homeopathy's efficacy, dark matter, and constellations' ``stick-figure projections,'' as indicated by some traditional cultures, all possibly involving neutrino strings. To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.NES07.C2.5

Jorge A. Swieca's contributions to quantum field theory in the 60s and 70s and their relevance in present research

NASA Astrophysics Data System (ADS)

Schroer, B.

2010-07-01

After revisiting some high points of particle physics and QFT of the two decades from 1960 to 1980, I comment on the work by Jorge André Swieca. I explain how it fits into the quantum field theory during these two decades and draw attention to its relevance to the ongoing particle physics research. A particular aim of this article is to direct the readers mindfulness to the relevance of what at the time of Swieca was called “the Schwinger Higgs screening mechanism” which, together with recent ideas which generalize the concept of gauge theories, has all the ingredients to revolutionize the issue of gauge theories and the standard model.

Cosmological evolution of the Higgs boson's vacuum expectation value

NASA Astrophysics Data System (ADS)

Calmet, Xavier

2017-11-01

We point out that the expansion of the universe leads to a cosmological time evolution of the vacuum expectation of the Higgs boson. Within the standard model of particle physics, the cosmological time evolution of the vacuum expectation of the Higgs leads to a cosmological time evolution of the masses of the fermions and of the electroweak gauge bosons, while the scale of Quantum Chromodynamics (QCD) remains constant. Precise measurements of the cosmological time evolution of μ =m_e/m_p, where m_e and m_p are, respectively, the electron and proton mass (which is essentially determined by the QCD scale), therefore provide a test of the standard models of particle physics and of cosmology. This ratio can be measured using modern atomic clocks.

Classical Electrodynamics: Problems with solutions; Problems with solutions

NASA Astrophysics Data System (ADS)

Likharev, Konstantin K.

2018-06-01

l Advanced Physics is a series comprising four parts: Classical Mechanics, Classical Electrodynamics, Quantum Mechanics and Statistical Mechanics. Each part consists of two volumes, Lecture notes and Problems with solutions, further supplemented by an additional collection of test problems and solutions available to qualifying university instructors. This volume, Classical Electrodynamics: Lecture notes is intended to be the basis for a two-semester graduate-level course on electricity and magnetism, including not only the interaction and dynamics charged point particles, but also properties of dielectric, conducting, and magnetic media. The course also covers special relativity, including its kinematics and particle-dynamics aspects, and electromagnetic radiation by relativistic particles.

Spatial and velocity statistics of inertial particles in turbulent flows

NASA Astrophysics Data System (ADS)

Bec, J.; Biferale, L.; Cencini, M.; Lanotte, A. S.; Toschi, F.

2011-12-01

Spatial and velocity statistics of heavy point-like particles in incompressible, homogeneous, and isotropic three-dimensional turbulence is studied by means of direct numerical simulations at two values of the Taylor-scale Reynolds number Reλ ~ 200 and Reλ ~ 400, corresponding to resolutions of 5123 and 20483 grid points, respectively. Particles Stokes number values range from St ≈ 0.2 to 70. Stationary small-scale particle distribution is shown to display a singular -multifractal- measure, characterized by a set of generalized fractal dimensions with a strong sensitivity on the Stokes number and a possible, small Reynolds number dependency. Velocity increments between two inertial particles depend on the relative weight between smooth events - where particle velocity is approximately the same of the fluid velocity-, and caustic contributions - when two close particles have very different velocities. The latter events lead to a non-differentiable small-scale behaviour for the relative velocity. The relative weight of these two contributions changes at varying the importance of inertia. We show that moments of the velocity difference display a quasi bi-fractal-behavior and that the scaling properties of velocity increments for not too small Stokes number are in good agreement with a recent theoretical prediction made by K. Gustavsson and B. Mehlig arXiv: 1012.1789v1 [physics.flu-dyn], connecting the saturation of velocity scaling exponents with the fractal dimension of particle clustering.

Implications of Ultrahigh Energy Air Showers for Physics and Astrophysics

NASA Technical Reports Server (NTRS)

Stecker, F. W.; White, Nicholas E. (Technical Monitor)

2002-01-01

The primary ultrahigh energy particles which produce giant extensive air showers in the Earth atmosphere present an intriguing mystery from two points of view: (1) How are the base particles produced with such astounding energies, eight orders of magnitude higher than those produced by the best man-made terrestrial accelerators? (2) Since they are most likely extragalactic in origin, how do they reach us from extragalactic distances without suffering the severe losses expected from interactions with the 2.7 K thermal cosmic background photons, the so called GZK effect? The answers to these questions may involve new physics: violations of special relativity, grand unification theories, and quantum gravity theories involving large extra dimensions. They may involve new astrophysical sources, "zevatrons". Or some heretofore totally unknown physics or astrophysics may hold the answer. I will discuss here the mysteries involving the production and extragalactic propagation of ultrahigh energy cosmic rays and some suggested possible solutions.

Derivation of the Biot-Savart Law from Ampere's Law Using the Displacement Current

NASA Astrophysics Data System (ADS)

Buschauer, Robert

2013-12-01

The equation describing the magnetic field due to a single, nonrelativistic charged particle moving at constant velocity is often referred to as the "Biot-Savart law for a point charge." Introductory calculus-based physics books usually state this law without proof.2 Advanced texts often present it either without proof or as a special case of a complicated mathematical formalism.3 Either way, little or no physical insight is provided to the student regarding the underlying physics. This paper presents a novel, basic, and transparent derivation of the Biot-Savart law for a point charge based only on Maxwell's displacement current term in Ampere's law. This derivation can serve many pedagogical purposes. For example, it can be used as lecture material at any academic level to obtain the Biot-Savart law for a point charge from simple principles. It can also serve as a practical example of the important fact that a changing electric flux produces a magnetic field.

Implications of the 750 GeV γγ Resonance as a Case Study for the International Linear Collider

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

Fujii, Keisuke; Grojean, Christophe; Peskin, Michael E.

If the γγ resonance at 750 GeV suggested by 2015 LHC data turns out to be a real effect, what are the implications for the physics case and upgrade path of the International Linear Collider? Whether or not the resonance is confirmed, this question provides an interesting case study testing the robustness of the ILC physics case. In this note, we address this question with two points: (1) Almost all models proposed for the new 750 GeV particle require additional new particles with electroweak couplings. The key elements of the 500 GeV ILC physics program - precision measurements of themore » Higgs boson, the top quark, and 4-fermion interactions - will powerfully discriminate among these models. This information will be important in conjunction with new LHC data, or alone, if the new particles accompanying the 750 GeV resonance are beyond the mass reach of the LHC. (2) Over a longer term, the energy upgrade of the ILC to 1 TeV already discussed in the ILC TDR will enable experiments in γγ and e +e - collisions to directly produce and study the 750 GeV particle from these unique initial states.« less

A relativistically interacting exactly solvable multi-time model for two massless Dirac particles in 1 + 1 dimensions

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

Lienert, Matthias, E-mail: lienert@math.lmu.de

2015-04-15

The question how to Lorentz transform an N-particle wave function naturally leads to the concept of a so-called multi-time wave function, i.e., a map from (space-time){sup N} to a spin space. This concept was originally proposed by Dirac as the basis of relativistic quantum mechanics. In such a view, interaction potentials are mathematically inconsistent. This fact motivates the search for new mechanisms for relativistic interactions. In this paper, we explore the idea that relativistic interaction can be described by boundary conditions on the set of coincidence points of two particles in space-time. This extends ideas from zero-range physics to amore » relativistic setting. We illustrate the idea at the simplest model which still possesses essential physical properties like Lorentz invariance and a positive definite density: two-time equations for massless Dirac particles in 1 + 1 dimensions. In order to deal with a spatio-temporally non-trivial domain, a necessity in the multi-time picture, we develop a new method to prove existence and uniqueness of classical solutions: a generalized version of the method of characteristics. Both mathematical and physical considerations are combined to precisely formulate and answer the questions of probability conservation, Lorentz invariance, interaction, and antisymmetry.« less

Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

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

Guimaraes, C. C.; Sene, F. F.; Martinelli, J. R.

2009-06-03

The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for monoenergetic electrons in water, which is an important reference medium for nuclear medicine. The three different physical models of electromagnetic interactions provided by GEANT4 - Low Energy, Penelope and Standard - were employed. To verify the adequacy of these models,more » the results were compared with references from the literature. For all energies and physical models, the agreement between calculated DPKs and reported values is satisfactory.« less

Numerical simulation support to the ESA/THOR mission

NASA Astrophysics Data System (ADS)

Valentini, F.; Servidio, S.; Perri, S.; Perrone, D.; De Marco, R.; Marcucci, M. F.; Daniele, B.; Bruno, R.; Camporeale, E.

2016-12-01

THOR is a spacecraft concept currently undergoing study phase as acandidate for the next ESA medium size mission M4. THOR has been designedto solve the longstanding physical problems of particle heating andenergization in turbulent plasmas. It will provide high resolutionmeasurements of electromagnetic fields and particle distribution functionswith unprecedented resolution, with the aim of exploring the so-calledkinetic scales. We present the numerical simulation framework which is supporting the THOR mission during the study phase. The THOR teamincludes many scientists developing and running different simulation codes(Eulerian-Vlasov, Particle-In-Cell, Gyrokinetics, Two-fluid, MHD, etc.),addressing the physics of plasma turbulence, shocks, magnetic reconnectionand so on.These numerical codes are being used during the study phase, mainly withthe aim of addressing the following points:(i) to simulate the response of real particle instruments on board THOR, byemploying an electrostatic analyser simulator which mimics the response ofthe CSW, IMS and TEA instruments to the particle velocity distributions ofprotons, alpha particle and electrons, as obtained from kinetic numericalsimulations of plasma turbulence.(ii) to compare multi-spacecraft with single-spacecraft configurations inmeasuring current density, by making use of both numerical models ofsynthetic turbulence and real data from MMS spacecraft.(iii) to investigate the validity of the Taylor hypothesis indifferent configurations of plasma turbulence

Solution on the Bethe lattice of a hard core athermal gas with two kinds of particles.

PubMed

Oliveira, Tiago J; Stilck, Jürgen F

2011-11-14

Athermal lattice gases of particles with first neighbor exclusion have been studied for a long time as simple models exhibiting a fluid-solid transition. At low concentration the particles occupy randomly both sublattices, but as the concentration is increased one of the sublattices is occupied preferentially. Here, we study a mixed lattice gas with excluded volume interactions only in the grand-canonical formalism with two kinds of particles: small ones, which occupy a single lattice site and large ones, which, when placed on a site, do not allow other particles to occupy its first neighbors also. We solve the model on a Bethe lattice of arbitrary coordination number q. In the parameter space defined by the activities of both particles, at low values of the activity of small particles (z(1)) we find a continuous transition from the fluid to the solid phase as the activity of large particles (z(2)) is increased. At higher values of z(1) the transition becomes discontinuous, both regimes are separated by a tricritical point. The critical line has a negative slope at z(1) = 0 and displays a minimum before reaching the tricritical point, so that a re-entrant behavior is observed for constant values of z(2) in the region of low density of small particles. The isobaric curves of the total density of particles as a function of the density or the activity of small particles show a minimum in the fluid phase. © 2011 American Institute of Physics

In search of elementary spin 0 particles

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

Krasny, Mieczyslaw Witold, E-mail: krasny@lpnhep.in2p3.fr; Płaczek, Wiesław

2015-01-15

The Standard Model of strong and electroweak interactions uses point-like spin 1/2 particles as the building bricks of matter and point-like spin 1 particles as the force carriers. One of the most important questions to be answered by the present and future particle physics experiments is whether the elementary spin 0 particles exist, and if they do, what are their interactions with the spin 1/2 and spin 1 particles. Spin 0 particles have been searched extensively over the last decades. Several initial claims of their discoveries were finally disproved in the final experimental scrutiny process. The recent observation of themore » excess of events at the LHC in the final states involving a pair of vector bosons, or photons, is commonly interpreted as the discovery of the first elementary scalar particle, the Higgs boson. In this paper we recall examples of claims and subsequent disillusions in precedent searches spin 0 particles. We address the question if the LHC Higgs discovery can already be taken for granted, or, as it turned out important in the past, whether it requires a further experimental scrutiny before the existence of the first ever found elementary scalar particle is proven beyond any doubt. An example of the Double Drell–Yan process for which such a scrutiny is indispensable is discussed in some detail. - Highlights: • We present a short history of searches of spin 0 particles. • We construct a model of the Double Drell–Yan Process (DDYP) at the LHC. • We investigate the contribution of the DDYP to the Higgs searches background.« less

Effective charges and virial pressure of concentrated macroion solutions

DOE PAGES

Boon, Niels; Guerrero-García, Guillermo Ivan; van Roij, René; ...

2015-07-13

The stability of colloidal suspensions is crucial in a wide variety of processes, including the fabrication of photonic materials and scaffolds for biological assemblies. The ionic strength of the electrolyte that suspends charged colloids is widely used to control the physical properties of colloidal suspensions. The extensively used two-body Derjaguin-Landau-Verwey-Overbeek (DLVO) approach allows for a quantitative analysis of the effective electrostatic forces between colloidal particles. DLVO relates the ionic double layers, which enclose the particles, to their effective electrostatic repulsion. Nevertheless, the double layer is distorted at high macroion volume fractions. Therefore, DLVO cannot describe the many-body effects that arisemore » in concentrated suspensions. In this paper, we show that this problem can be largely resolved by identifying effective point charges for the macroions using cell theory. This extrapolated point charge (EPC) method assigns effective point charges in a consistent way, taking into account the excluded volume of highly charged macroions at any concentration, and thereby naturally accounting for high volume fractions in both salt-free and added-salt conditions. We provide an analytical expression for the effective pair potential and validate the EPC method by comparing molecular dynamics simulations of macroions and monovalent microions that interact via Coulombic potentials to simulations of macroions interacting via the derived EPC effective potential. The simulations reproduce the macroion-macroion spatial correlation and the virial pressure obtained with the EPC model. Finally, our findings provide a route to relate the physical properties such as pressure in systems of screened Coulomb particles to experimental measurements.« less

A rational explanation of wave-particle duality of light

NASA Astrophysics Data System (ADS)

Rashkovskiy, S. A.

2013-10-01

The wave-particle duality is a fundamental property of the nature. At the same time, it is one of the greatest mysteries of modern physics. This gave rise to a whole direction in quantum physics - the interpretation of quantum mechanics. The Wiener experiments demonstrating the wave-particle duality of light are discussed. It is shown that almost all interpretations of quantum mechanics allow explaining the double-slit experiments, but are powerless to explain the Wiener experiments. The reason of the paradox, associated with the wave-particle duality is analyzed. The quantum theory consists of two independent parts: (i) the dynamic equations describing the behavior of a quantum object (for example, the Schrodinger or Maxwell equations), and (ii) the Born's rule, the relation between the wave function and the probability of finding the particle at a given point. It is shown that precisely the Born's rule results in paradox in explaining the wave-particle duality. In order to eliminate this paradox, we propose a new rational interpretation of the wave-particle duality and associated new rule, connecting the corpuscular and wave properties of quantum objects. It is shown that this new rational interpretation of the wave-particle duality allows using the classic images of particle and wave in explaining the quantum mechanical and optical phenomena, does not result in paradox in explaining the doubleslit experiments and Wiener experiments, and does not contradict to the modern quantum mechanical concepts. It is shown that the Born's rule follows immediately from proposed new rules as an approximation.

Positive spaces, generalized semi-densities, and quantum interactions

NASA Astrophysics Data System (ADS)

Canarutto, Daniel

2012-03-01

The basics of quantum particle physics on a curved Lorentzian background are expressed in a formulation which has original aspects and exploits some non-standard mathematical notions. In particular, positive spaces and generalized semi-densities (in a distributional sense) are shown to link, in a natural way, discrete multi-particle spaces to distributional bundles of quantum states. The treatment of spinor and boson fields is partly original also from an algebraic point of view and suggests a non-standard approach to quantum interactions. The case of electroweak interactions provides examples.

The uses of isospin in early nuclear and particle physics

NASA Astrophysics Data System (ADS)

Borrelli, Arianna

2017-11-01

This paper reconstructs the early history of isospin up to and including its employment in 1951sbnd 52 to conceptualize high-energy pion-proton scattering. Studying the history of isospin serves as an entry point for investigating the interplay of theoretical and experimental practices in early nuclear and particle physics, showing the complexity of processes of knowledge construction which have often been presented as straightforward both in physicists' recollections and in the historiography of science. The story of isospin has often been told in terms of the discovery of the first ;intrinsic property; of elementary particles, but I will argue that the isospin formalism emerged and was further developed because it proved to be a useful tool to match theory and experiment within the steadily broadening field of high-energy (nuclear) physics. Isospin was variously appropriated and adapted in the course of two decades, before eventually the physical-mathematical implications of its uses started being spelled out. The case study also highlights some interesting features of high-energy physics around 1950: the contribution to post-war research of theoretical methods developed before and during the war, the role of young theoretical post-docs in mediating between theorists and experimenters, and the importance of traditional formalisms such as those of spin and angular momentum as a template both for formalizing and conceptualizing experimental results.

A FPGA-based Cluster Finder for CMOS Monolithic Active Pixel Sensors of the MIMOSA-26 Family

NASA Astrophysics Data System (ADS)

Li, Qiyan; Amar-Youcef, S.; Doering, D.; Deveaux, M.; Fröhlich, I.; Koziel, M.; Krebs, E.; Linnik, B.; Michel, J.; Milanovic, B.; Müntz, C.; Stroth, J.; Tischler, T.

2014-06-01

CMOS Monolithic Active Pixel Sensors (MAPS) demonstrated excellent performances in the field of charged particle tracking. Among their strong points are an single point resolution few μm, a light material budget of 0.05% X0 in combination with a good radiation tolerance and high rate capability. Those features make the sensors a valuable technology for vertex detectors of various experiments in heavy ion and particle physics. To reduce the load on the event builders and future mass storage systems, we have developed algorithms suited for preprocessing and reducing the data streams generated by the MAPS. This real-time processing employs remaining free resources of the FPGAs of the readout controllers of the detector and complements the on-chip data reduction circuits of the MAPS.

Higgsploding universe

NASA Astrophysics Data System (ADS)

Khoze, Valentin V.; Spannowsky, Michael

2017-10-01

Higgsplosion is a dynamical mechanism that introduces an exponential suppression of quantum fluctuations beyond the Higgsplosion energy scale E* and further guarantees perturbative unitarity in multi-Higgs production processes. By calculating the Higgsplosion scale for spin 0, 1 /2 , 1 and 2 particles at leading order, we argue that Higgsplosion regulates all n-point functions, thereby embedding the standard model of particle physics and its extensions into an asymptotically safe theory. There are no Landau poles and the Higgs self-coupling stays positive. Asymptotic safety is of particular interest for theories of particle physics that include quantum gravity. We argue that in a Hippsloding theory one cannot probe shorter and shorter length scales by increasing the energy of the collision beyond the Higgsplosion energy and there is a minimal length set by r*˜1 /E* that can be probed. We further show that Higgsplosion is consistent and not in conflict with models of inflation and the existence of axions. There is also a possibility of testing Higgsplosion experimentally at future high energy experiments.

New technology for separating resin powder and fiberglass powder from fiberglass-resin powder of waste printed circuit boards.

PubMed

Li, Jia; Gao, Bei; Xu, Zhenming

2014-05-06

New recycling technologies have been developed lately to enhance the value of the fiberglass powder-resin powder fraction (FRP) from waste printed circuit boards. The definite aim of the present paper is to present some novel methods that use the image forces for the separation of the resin powder and fiberglass powder generated from FRP during the corona electrostatic separating process. The particle shape charactization and particle trajectory simulation were performed on samples of mixed non-metallic particles. The simulation results pointed out that particles of resin powder and particles of fiberglass powder had different detach trajectories at the conditions of the same size and certain device parameters. An experiment carried out using a corona electrostatic separator validated the possibility of sorting these particles based on the differences in their shape characteristics. The differences in the physical properties of the different types of particles provided the technical basis for the development of electrostatic separation technologies for the recycling industry.

Discovery of naked charm particles and lifetime differences among charm species using nuclear emulsion techniques innovated in Japan

PubMed Central

NIU, Kiyoshi

2008-01-01

This is a historical review of the discovery of naked charm particles and lifetime differences among charm species. These discoveries in the field of cosmic-ray physics were made by the innovation of nuclear emulsion techniques in Japan. A pair of naked charm particles was discovered in 1971 in a cosmic-ray interaction, three years prior to the discovery of the hidden charm particle, J/Ψ, in western countries. Lifetime differences between charged and neutral charm particles were pointed out in 1975, which were later re-confirmed by the collaborative Experiment E531 at Fermilab. Japanese physicists led by K.Niu made essential contributions to it with improved emulsion techniques, complemented by electronic detectors. This review also discusses the discovery of artificially produced naked charm particles by us in an accelerator experiment at Fermilab in 1975 and of multiple-pair productions of charm particles in a single interaction in 1987 by the collaborative Experiment WA75 at CERN. PMID:18941283

Deformation Theory and Physics Model Building

NASA Astrophysics Data System (ADS)

Sternheimer, Daniel

2006-08-01

The mathematical theory of deformations has proved to be a powerful tool in modeling physical reality. We start with a short historical and philosophical review of the context and concentrate this rapid presentation on a few interrelated directions where deformation theory is essential in bringing a new framework - which has then to be developed using adapted tools, some of which come from the deformation aspect. Minkowskian space-time can be deformed into Anti de Sitter, where massless particles become composite (also dynamically): this opens new perspectives in particle physics, at least at the electroweak level, including prediction of new mesons. Nonlinear group representations and covariant field equations, coming from interactions, can be viewed as some deformation of their linear (free) part: recognizing this fact can provide a good framework for treating problems in this area, in particular global solutions. Last but not least, (algebras associated with) classical mechanics (and field theory) on a Poisson phase space can be deformed to (algebras associated with) quantum mechanics (and quantum field theory). That is now a frontier domain in mathematics and theoretical physics called deformation quantization, with multiple ramifications, avatars and connections in both mathematics and physics. These include representation theory, quantum groups (when considering Hopf algebras instead of associative or Lie algebras), noncommutative geometry and manifolds, algebraic geometry, number theory, and of course what is regrouped under the name of M-theory. We shall here look at these from the unifying point of view of deformation theory and refer to a limited number of papers as a starting point for further study.

Stochastic optimization of GeantV code by use of genetic algorithms

DOE PAGES

Amadio, G.; Apostolakis, J.; Bandieramonte, M.; ...

2017-10-01

GeantV is a complex system based on the interaction of different modules needed for detector simulation, which include transport of particles in fields, physics models simulating their interactions with matter and a geometrical modeler library for describing the detector and locating the particles and computing the path length to the current volume boundary. The GeantV project is recasting the classical simulation approach to get maximum benefit from SIMD/MIMD computational architectures and highly massive parallel systems. This involves finding the appropriate balance between several aspects influencing computational performance (floating-point performance, usage of off-chip memory bandwidth, specification of cache hierarchy, etc.) andmore » handling a large number of program parameters that have to be optimized to achieve the best simulation throughput. This optimization task can be treated as a black-box optimization problem, which requires searching the optimum set of parameters using only point-wise function evaluations. Here, the goal of this study is to provide a mechanism for optimizing complex systems (high energy physics particle transport simulations) with the help of genetic algorithms and evolution strategies as tuning procedures for massive parallel simulations. One of the described approaches is based on introducing a specific multivariate analysis operator that could be used in case of resource expensive or time consuming evaluations of fitness functions, in order to speed-up the convergence of the black-box optimization problem.« less

Stochastic optimization of GeantV code by use of genetic algorithms

NASA Astrophysics Data System (ADS)

Amadio, G.; Apostolakis, J.; Bandieramonte, M.; Behera, S. P.; Brun, R.; Canal, P.; Carminati, F.; Cosmo, G.; Duhem, L.; Elvira, D.; Folger, G.; Gheata, A.; Gheata, M.; Goulas, I.; Hariri, F.; Jun, S. Y.; Konstantinov, D.; Kumawat, H.; Ivantchenko, V.; Lima, G.; Nikitina, T.; Novak, M.; Pokorski, W.; Ribon, A.; Seghal, R.; Shadura, O.; Vallecorsa, S.; Wenzel, S.

2017-10-01

GeantV is a complex system based on the interaction of different modules needed for detector simulation, which include transport of particles in fields, physics models simulating their interactions with matter and a geometrical modeler library for describing the detector and locating the particles and computing the path length to the current volume boundary. The GeantV project is recasting the classical simulation approach to get maximum benefit from SIMD/MIMD computational architectures and highly massive parallel systems. This involves finding the appropriate balance between several aspects influencing computational performance (floating-point performance, usage of off-chip memory bandwidth, specification of cache hierarchy, etc.) and handling a large number of program parameters that have to be optimized to achieve the best simulation throughput. This optimization task can be treated as a black-box optimization problem, which requires searching the optimum set of parameters using only point-wise function evaluations. The goal of this study is to provide a mechanism for optimizing complex systems (high energy physics particle transport simulations) with the help of genetic algorithms and evolution strategies as tuning procedures for massive parallel simulations. One of the described approaches is based on introducing a specific multivariate analysis operator that could be used in case of resource expensive or time consuming evaluations of fitness functions, in order to speed-up the convergence of the black-box optimization problem.

Stochastic optimization of GeantV code by use of genetic algorithms

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

Amadio, G.; Apostolakis, J.; Bandieramonte, M.

GeantV is a complex system based on the interaction of different modules needed for detector simulation, which include transport of particles in fields, physics models simulating their interactions with matter and a geometrical modeler library for describing the detector and locating the particles and computing the path length to the current volume boundary. The GeantV project is recasting the classical simulation approach to get maximum benefit from SIMD/MIMD computational architectures and highly massive parallel systems. This involves finding the appropriate balance between several aspects influencing computational performance (floating-point performance, usage of off-chip memory bandwidth, specification of cache hierarchy, etc.) andmore » handling a large number of program parameters that have to be optimized to achieve the best simulation throughput. This optimization task can be treated as a black-box optimization problem, which requires searching the optimum set of parameters using only point-wise function evaluations. Here, the goal of this study is to provide a mechanism for optimizing complex systems (high energy physics particle transport simulations) with the help of genetic algorithms and evolution strategies as tuning procedures for massive parallel simulations. One of the described approaches is based on introducing a specific multivariate analysis operator that could be used in case of resource expensive or time consuming evaluations of fitness functions, in order to speed-up the convergence of the black-box optimization problem.« less

Center for Theoretical Underground Physics and Related Fields. CETUP2015/ Particle Physics and Cosmology Conference. PPC2015)

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

Szczerbinska, Barbara

For last five years Center for Theoretical Underground Physics and Related Areas (CETUP*) serves as a collaboration point for scientists from around the world interested in theoretical and experimental aspects of underground science. The mission of CETUP* is to promote an organized research in physics, astrophysics, geoscience, geomicrobiology and other fields related to the underground science and provide a stimulating environment for creative thinking and open communication between researches of varying ages and nationalities in dynamic atmosphere of intense scientific interactions. Scientists invited to participate in the program will not only provide theoretical support to the underground science, but theymore » will also examine core questions of the 21st century including: What is dark matter? How well do we know the neutrino parameters?, How have neutrinos shaped the evolution of the universe?, How were the heavy elements made?, What are the fundamental underlying symmetries of the Universe? Is there a Grand Unified Theory of the Universe? How do supernovae explode? Studies of Neutrino Physics and Dark Matter are of high interest to particle and nuclear physicists, astrophysicists and cosmologists. Ongoing and proposed Neutrino and Dark Matter experiments are expected to unveil the answers to fundamental questions about the Universe. This year summer program was focused exactly on these subjects bringing together experts in dark matter, neutrino physics, particle physics, nuclear physics and astrophysics and cosmology. CETUP*2015 consisted of 5 week long program (June 14 – July 18, 2015) covering various theoretical and experimental aspects in these research areas. The two week long session on Dark Matter physics (June 14 – June 26) was followed by two week long program on Neutrino physics (July 6 – July 18). The international conference entitled IXth International Conference on Interconnection Between Particle Physics and Cosmology (PPC) was hosted at CETUP* in the time between the Dark Matter and Neutrino workshops (June 29 – July 3) covering the subjects of dark matter, dark energy, neutrino physics, gravitational waves, collider physics and many others. PPC brought about 90 national and international participants. Started at Texas A&M University in 2007, PPC travelled to many places which include Geneva (Switzerland), Turin (Italy), Seoul (South Korea) and Leon (Mexico) over last few years. The objectives of CETUP*2015 and PPC2015 were to analyze the connection between dark matter and particle physics models, discuss the connections among dark matter, grand unification models and recent neutrino results and predictions for possible experiments.« less

On the origin of comets

NASA Technical Reports Server (NTRS)

Mendis, A.; Alfven, H.

1976-01-01

Physico-chemical processes leading to the dynamic formation and physical evolution of comets are reviewed in relationship to the various theories that propose solar origins, protoplanetary origins, planetary origins and interstellar origins. Evidence points to the origins of comets by the growth and agglomeration of small particles from gas and dust at very low temperatures at undetermined regions in space.

GPU acceleration of Eulerian-Lagrangian particle-laden turbulent flow simulations

NASA Astrophysics Data System (ADS)

Richter, David; Sweet, James; Thain, Douglas

2017-11-01

The Lagrangian point-particle approximation is a popular numerical technique for representing dispersed phases whose properties can substantially deviate from the local fluid. In many cases, particularly in the limit of one-way coupled systems, large numbers of particles are desired; this may be either because many physical particles are present (e.g. LES of an entire cloud), or because the use of many particles increases statistical convergence (e.g. high-order statistics). Solving the trajectories of very large numbers of particles can be problematic in traditional MPI implementations, however, and this study reports the benefits of using graphical processing units (GPUs) to integrate the particle equations of motion while preserving the original MPI version of the Eulerian flow solver. It is found that GPU acceleration becomes cost effective around one million particles, and performance enhancements of up to 15x can be achieved when O(108) particles are computed on the GPU rather than the CPU cluster. Optimizations and limitations will be discussed, as will prospects for expanding to two- and four-way coupled systems. ONR Grant No. N00014-16-1-2472.

Inflation, quintessence, and the origin of mass

NASA Astrophysics Data System (ADS)

Wetterich, C.

2015-08-01

In a unified picture both inflation and present dynamical dark energy arise from the same scalar field. The history of the Universe describes a crossover from a scale invariant "past fixed point" where all particles are massless, to a "future fixed point" for which spontaneous breaking of the exact scale symmetry generates the particle masses. The cosmological solution can be extrapolated to the infinite past in physical time - the universe has no beginning. This is seen most easily in a frame where particle masses and the Planck mass are field-dependent and increase with time. In this "freeze frame" the Universe shrinks and heats up during radiation and matter domination. In the equivalent, but singular Einstein frame cosmic history finds the familiar big bang description. The vicinity of the past fixed point corresponds to inflation. It ends at a first stage of the crossover. A simple model with no more free parameters than ΛCDM predicts for the primordial fluctuations a relation between the tensor amplitude r and the spectral index n, r = 8.19 (1 - n) - 0.137. The crossover is completed by a second stage where the beyond-standard-model sector undergoes the transition to the future fixed point. The resulting increase of neutrino masses stops a cosmological scaling solution, relating the present dark energy density to the present neutrino mass. At present our simple model seems compatible with all observational tests. We discuss how the fixed points can be rooted within quantum gravity in a crossover between ultraviolet and infrared fixed points. Then quantum properties of gravity could be tested both by very early and late cosmology.

Anisotropic Weyl fermions from the quasiparticle excitation spectrum of a 3D Fulde-Ferrell superfluid.

PubMed

Xu, Yong; Chu, Rui-Lin; Zhang, Chuanwei

2014-04-04

Weyl fermions, first proposed for describing massless chiral Dirac fermions in particle physics, have not been observed yet in experiments. Recently, much effort has been devoted to explore Weyl fermions around band touching points of single-particle energy dispersions in certain solid state materials (named Weyl semimetals), similar as graphene for Dirac fermions. Here we show that such Weyl semimetals also exist in the quasiparticle excitation spectrum of a three-dimensional spin-orbit-coupled Fulde-Ferrell superfluid. By varying Zeeman fields, the properties of Weyl fermions, such as their creation and annihilation, number and position, as well as anisotropic linear dispersions around band touching points, can be tuned. We study the manifestation of anisotropic Weyl fermions in sound speeds of Fulde-Ferrell fermionic superfluids, which are detectable in experiments.

The phenomenology of maverick dark matter

NASA Astrophysics Data System (ADS)

Krusberg, Zosia Anna Celina

Astrophysical observations from galactic to cosmological scales point to a substantial non-baryonic component to the universe's total matter density. Although very little is presently known about the physical properties of dark matter, its existence offers some of the most compelling evidence for physics beyond the standard model (BSM). In the weakly interacting massive particle (WIMP) scenario, the dark matter consists of particles that possess weak-scale interactions with the particles of the standard model, offering a compelling theoretical framework that allows us to understand the relic abundance of dark matter as a natural consequence of the thermal history of the early universe. From the perspective of particle physics phenomenology, the WIMP scenario is appealing for two additional reasons. First, many theories of BSM physics contain attractive WIMP candidates. Second, the weak-scale interactions between WIMPs and standard model particles imply the possibility of detecting scatterings between relic WIMPs and detector nuclei in direct detection experiments, products of WIMP annihilations at locations throughout the galaxy in indirect detection programs, and WIMP production signals at high-energy particle colliders. In this work, we use an effective field theory approach to study model-independent dark matter phenomenology in direct detection and collider experiments. The maverick dark matter scenario is defined by an effective field theory in which the WIMP is the only new particle within the energy range accessible to the Large Hadron Collider (LHC). Although certain assumptions are necessary to keep the problem tractable, we describe our WIMP candidate generically by specifying only its spin and dominant interaction form with standard model particles. Constraints are placed on the masses and coupling constants of the maverick WIMPs using the Wilkinson Microwave Anisotropy Probe (WMAP) relic density measurement and direct detection exclusion data from both spin-independent (XENON100 and SuperCDMS) and spin-dependent (COUPP) experiments. We further study the distinguishability of maverick WIMP production signals at the Tevatron and the LHC---at its early and nominal configurations---using standard simulation packages, place constraints on maverick WIMP properties using existing collider data, and determine projected mass reaches in future data from both colliders. We find ourselves in a unique era of theoretically-motivated, high-precision dark matter searches that hold the potential to give us important insights, not only into the nature of dark matter, but also into the physics that lies beyond the standard model.

Measurement of argon neutral velocity distribution functions near an absorbing boundary in a plasma

NASA Astrophysics Data System (ADS)

Short, Zachary; Thompson, Derek; Good, Timothy; Scime, Earl

2016-10-01

Neutral particle distributions are critical to the study of plasma boundary interactions, where ion-neutral collisions, e.g. via charge exchange, may modify energetic particle populations impacting the boundary surface. Neutral particle behavior at absorbing boundaries thus underlies a number of important plasma physics issues, such as wall loading in fusion devices and anomalous erosion in Hall thruster channels. Neutral velocity distribution functions (NVDFs) are measured using laser-induced fluorescence (LIF). Our LIF scheme excites the 1s4 non-metastable state of neutral argon with 667.913 nm photons. The subsequent decay emission at 750.590 nm is recorded synchronously with injection laser frequency. Measurements are performed near a grounded boundary immersed in a cylindrical helicon plasma, with the boundary plate oriented at an oblique angle to the magnetic field. NVDFs are recorded in multiple velocity dimensions and in a three-dimensional volume, enabling point-to-point comparisons with NVDF predictions from particle-in-cell models as well as comparisons with ion velocity distribution function measurements obtained in the same regions through Ar-II LIF. This work is supported by US National Science Foundation Grant Number PHYS-1360278.

39 Questionable Assumptions in Modern Physics

NASA Astrophysics Data System (ADS)

Volk, Greg

2009-03-01

The growing body of anomalies in new energy, low energy nuclear reactions, astrophysics, atomic physics, and entanglement, combined with the failure of the Standard Model and string theory to predict many of the most basic fundamental phenomena, all point to a need for major new paradigms. Not Band-Aids, but revolutionary new ways of conceptualizing physics, in the spirit of Thomas Kuhn's The Structure of Scientific Revolutions. This paper identifies a number of long-held, but unproven assumptions currently being challenged by an increasing number of alternative scientists. Two common themes, both with venerable histories, keep recurring in the many alternative theories being proposed: (1) Mach's Principle, and (2) toroidal, vortex particles. Matter-based Mach's Principle differs from both space-based universal frames and observer-based Einsteinian relativity. Toroidal particles, in addition to explaining electron spin and the fundamental constants, satisfy the basic requirement of Gauss's misunderstood B Law, that motion itself circulates. Though a comprehensive theory is beyond the scope of this paper, it will suggest alternatives to the long list of assumptions in context.

Stochastic driven systems far from equilibrium

NASA Astrophysics Data System (ADS)

Kim, Kyung Hyuk

We study the dynamics and steady states of two systems far from equilibrium: a 1-D driven lattice gas and a driven Brownian particle with inertia. (1) We investigate the dynamical scaling behavior of a 1-D driven lattice gas model with two species of particles hopping in opposite directions. We confirm numerically that the dynamic exponent is equal to z = 1.5. We show analytically that a quasi-particle representation relates all phase points to a special phase line directly related to the single-species asymmetric simple exclusion process. Quasi-particle two-point correlations decay exponentially, and in such a manner that quasi-particles of opposite charge dynamically screen each other with a special balance. The balance encompasses all over the phase space. These results indicate that the model belongs to the Kardar-Parisi-Zhang (KPZ) universality class. (2) We investigate the non-equilibrium thermodynamics of a Brownian particle with inertia under feedback control of its inertia. We find such open systems can act as a molecular refrigerator due to an entropy pumping mechanism. We extend the fluctuation theorems to the refrigerator. The entropy pumping modifies both the Jarzynski equality and the fluctuation theorems. We discover that the entropy pumping has a dual role of work and heat. We also investigate the thermodynamics of the particle under a hydrodynamic interaction described by a Langevin equation with a multiplicative noise. The Stratonovich stochastic integration prescription involved in the definition of heat is shown to be the unique physical choice.

An initial physical mechanism in the treatment of neurologic disorders with externally applied pico Tesla magnetic fields.

PubMed

Jacobson, J I; Yamanashi, W S

1995-04-01

The recent clinical studies describing the treatment of some neurological disorders with an externally applied pico Tesla (10(-12) Tesla, or 10(-8) gauss) magnetic field are considered from a physical view point. An equation relating the intrinsic (or rest) energy of a charged particle of mass m with its energy of interaction in an externally applied magnetic field B is presented. The equation represents an initial basic physical interaction as a part of a more complex biological mechanism to explain the therapeutic effects of externally applied magnetic fields in these and other neurologic disorders.

A physical mechanism in the treatment of neurologic disorders with externally applied pico Tesla magnetic fields.

PubMed

Jacobson, J I; Yamanashi, W S

1995-06-01

The clinical studies describing the treatment of some neurological disorders with an externally applied pico Tesla (10R Tesla, or 10(-8) gauss) magnetic field are considered from a physical view point. An equation relating the intrinsic or "rest" energy of a charged particle of mass with its energy of interaction in an externally applied magnetic field B is presented. The equation is proposed to represent an initial basic physical interaction as a part of a more complex biological mechanism to explain the therapeutic effects of externally applied magnetic fields in these and other neurologic disorders.

On a simple molecular–statistical model of a liquid-crystal suspension of anisometric particles

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

Zakhlevnykh, A. N., E-mail: anz@psu.ru; Lubnin, M. S.; Petrov, D. A.

2016-11-15

A molecular–statistical mean-field theory is constructed for suspensions of anisometric particles in nematic liquid crystals (NLCs). The spherical approximation, well known in the physics of ferromagnetic materials, is considered that allows one to obtain an analytic expression for the free energy and simple equations for the orientational state of a suspension that describe the temperature dependence of the order parameters of the suspension components. The transition temperature from ordered to isotropic state and the jumps in the order parameters at the phase-transition point are studied as a function of the anchoring energy of dispersed particles to the matrix, the concentrationmore » of the impurity phase, and the size of particles. The proposed approach allows one to generalize the model to the case of biaxial ordering.« less

Coherent and Semiclassical States of a Charged Particle in Electromagnetic Fields

NASA Astrophysics Data System (ADS)

Pereira, A. S.

2018-06-01

In the present article, we extend our study (Bagrov et al., Braz. J. Phys. 45, 369, 2015) of generalized coherent states (GCS) of a one-dimensional particle considering such important physical system as a three-dimensional charged particle in electric and magnetic fields. Constructing GCS in a many-dimensional case, we meet technical complications that make the consideration nontrivial and instructive. The GCS of the system under consideration are constructed. We study the properties of this GCS such as completeness relations, minimization of uncertainty relations, and so on. We point out which family of the obtained GCS of a charged particle in a magnetic field is related to the CS constructed first by Malkin and Man'ko. We obtain conditions under which some of the GCS can be considered as semiclassical states (SS).

Coherent and Semiclassical States of a Charged Particle in Electromagnetic Fields

NASA Astrophysics Data System (ADS)

Pereira, A. S.

2018-03-01

In the present article, we extend our study (Bagrov et al., Braz. J. Phys. 45, 369, 2015) of generalized coherent states (GCS) of a one-dimensional particle considering such important physical system as a three-dimensional charged particle in electric and magnetic fields. Constructing GCS in a many-dimensional case, we meet technical complications that make the consideration nontrivial and instructive. The GCS of the system under consideration are constructed. We study the properties of this GCS such as completeness relations, minimization of uncertainty relations, and so on. We point out which family of the obtained GCS of a charged particle in a magnetic field is related to the CS constructed first by Malkin and Man'ko. We obtain conditions under which some of the GCS can be considered as semiclassical states (SS).

Correlated scattering states of N-body Coulomb systems

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

Berakdar, J.

1997-03-01

For N charged particles of equal masses moving in the field of a heavy residual charge, an approximate analytical solution of the many-body time-independent Schr{umlt o}dinger equation is derived at a total energy above the complete fragmentation threshold. All continuum particles are treated on equal footing. The proposed correlated wave function represents, to leading order, an exact solution of the many-body Schr{umlt o}dinger equation in the asymptotic region defined by large interparticle separations. Thus, in this asymptotic region the N-body Coulomb modifications to the plane-wave motion of free particles are rigorously estimated. It is shown that the Kato cusp conditionsmore » are satisfied by the derived wave function at all two-body coalescence points. An expression of the normalization of this wave function is also given. To render possible the calculations of scattering amplitudes for transitions leading to a four-body scattering state, an effective-charge method is suggested in which the correlations between the continuum particles are completely subsumed into effective interactions with the residual charge. Analytical expressions for these effective interactions are derived and discussed for physical situations. {copyright} {ital 1997} {ital The American Physical Society}« less

MoEDAL - a new light on the high-energy frontier

NASA Astrophysics Data System (ADS)

Fairbairn, Malcolm; Pinfold, James L.

2017-01-01

In 2010, the MoEDAL (MOnopole and Exotics Detector at the LHC) experiment at the Large Hadron Collider (LHC) was unanimously approved by European Centre for Nuclear Research's Research Board to start data taking in 2015. MoEDAL is a pioneering experiment designed to search for highly ionising manifestations of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics programme defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; does magnetic charge exist; what is the nature of dark matter; and, how did the Big Bang develop. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analysed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL's radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector designed to extend MoEDAL reach to mini-charged, minimally ionising particles is under study.

Relativistic particle in a box: Klein-Gordon versus Dirac equations

NASA Astrophysics Data System (ADS)

Alberto, Pedro; Das, Saurya; Vagenas, Elias C.

2018-03-01

The problem of a particle in a box is probably the simplest problem in quantum mechanics which allows for significant insight into the nature of quantum systems and thus is a cornerstone in the teaching of quantum mechanics. In relativistic quantum mechanics this problem allows also to highlight the implications of special relativity for quantum physics, namely the effect that spin has on the quantised energy spectra. To illustrate this point, we solve the problem of a spin zero relativistic particle in a one- and three-dimensional box using the Klein-Gordon equation in the Feshbach-Villars formalism. We compare the solutions and the energy spectra obtained with the corresponding ones from the Dirac equation for a spin one-half relativistic particle. We note the similarities and differences, in particular the spin effects in the relativistic energy spectrum. As expected, the non-relativistic limit is the same for both kinds of particles, since, for a particle in a box, the spin contribution to the energy is a relativistic effect.

Dynamical clustering of red blood cells in capillary vessels.

PubMed

Boryczko, Krzysztof; Dzwinel, Witold; Yuen, David A

2003-02-01

We have modeled the dynamics of a 3-D system consisting of red blood cells (RBCs), plasma and capillary walls using a discrete-particle approach. The blood cells and capillary walls are composed of a mesh of particles interacting with harmonic forces between nearest neighbors. We employ classical mechanics to mimic the elastic properties of RBCs with a biconcave disk composed of a mesh of spring-like particles. The fluid particle method allows for modeling the plasma as a particle ensemble, where each particle represents a collective unit of fluid, which is defined by its mass, moment of inertia, translational and angular momenta. Realistic behavior of blood cells is modeled by considering RBCs and plasma flowing through capillaries of various shapes. Three types of vessels are employed: a pipe with a choking point, a curved vessel and bifurcating capillaries. There is a strong tendency to produce RBC clusters in capillaries. The choking points and other irregularities in geometry influence both the flow and RBC shapes, considerably increasing the clotting effect. We also discuss other clotting factors coming from the physical properties of blood, such as the viscosity of the plasma and the elasticity of the RBCs. Modeling has been carried out with adequate resolution by using 1 to 10 million particles. Discrete particle simulations open a new pathway for modeling the dynamics of complex, viscoelastic fluids at the microscale, where both liquid and solid phases are treated with discrete particles. Figure A snapshot from fluid particle simulation of RBCs flowing along a curved capillary. The red color corresponds to the highest velocity. We can observe aggregation of RBCs at places with the most stagnant plasma flow.

Impact of secondary generated minerals on toxic element immobilization for air pollution control fly ash of a municipal solid waste incinerator.

PubMed

Kitamura, Hiroki; Dahlan, Astryd Viandila; Tian, Yu; Shimaoka, Takayuki; Yamamoto, Takashi; Takahashi, Fumitake

2018-05-12

Impacts of secondary generated minerals on mineralogical and physical immobilization of toxic elements were investigated for chelate-treated air pollution control (APC) fly ash of a municipal solid waste incinerator. Scanning electron microscope (SEM) observation showed that ettringite was generated after the moistening treatment with/without chelate. Although ettringite can incorporate toxic elements into its structure, elemental analysis by energy dispersive X-ray could not find concentrated points of toxic elements in ettringite structure. This implies that mineralogical immobilization of toxic element by the encapsulation to ettringite structure seems to be limited. Physical immobilization was also investigated by SEM observation of the same APC fly ash particles before and after the moistening treatment. The transfer of soluble elements was inhibited only when insoluble minerals such as gypsum were generated and covered the surface of fly ash particles. Neoformed insoluble minerals prevented soluble elements from leaching and transfer. However, such physical immobilization seems to be limited because insoluble mineral formation with surface coverage was monitored only one time of more than 20 observations. Although uncertainty owing to limited samples with limited observations should be considered, this study concludes that mineralogical and physical immobilization of toxic elements by secondary minerals is limited although secondary minerals are always generated on the surface of APC fly ash particles during chelate treatment.

The MoEDAL experiment at the LHC. Searching beyond the standard model

NASA Astrophysics Data System (ADS)

Pinfold, James L.

2016-11-01

MoEDAL is a pioneering experiment designed to search for highly ionizing avatars of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; what is the nature of dark matter; and, how did the big-bang develop. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors - analyzed offline by ultra fast scanning microscopes - sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL's radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector to extend MoEDAL's reach to millicharged, minimally ionizing, particles (MMIPs) is under study Finally we shall describe the next step for MoEDAL called Cosmic MoEDAL, where we define a very large high altitude array to take the search for highly ionizing avatars of new physics to higher masses that are available from the cosmos.

CMS Physics Technical Design Report, Volume II: Physics Performance

NASA Astrophysics Data System (ADS)

CMS Collaboration

2007-06-01

CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007. The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking—through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start-up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb -1 or less. The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z' and supersymmetric particles, B s production and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb -1 to 30 fb -1 . The Standard Model processes include QCD, B -physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the W and Z 0 boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated. This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2 6 describe examples of full analyses, with photons, electrons, muons, jets, missing E T , B-mesons and τ's, and for quarkonia in heavy ion collisions. Chapters 7 15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model.

Range Verification Methods in Particle Therapy: Underlying Physics and Monte Carlo Modeling

PubMed Central

Kraan, Aafke Christine

2015-01-01

Hadron therapy allows for highly conformal dose distributions and better sparing of organs-at-risk, thanks to the characteristic dose deposition as function of depth. However, the quality of hadron therapy treatments is closely connected with the ability to predict and achieve a given beam range in the patient. Currently, uncertainties in particle range lead to the employment of safety margins, at the expense of treatment quality. Much research in particle therapy is therefore aimed at developing methods to verify the particle range in patients. Non-invasive in vivo monitoring of the particle range can be performed by detecting secondary radiation, emitted from the patient as a result of nuclear interactions of charged hadrons with tissue, including β+ emitters, prompt photons, and charged fragments. The correctness of the dose delivery can be verified by comparing measured and pre-calculated distributions of the secondary particles. The reliability of Monte Carlo (MC) predictions is a key issue. Correctly modeling the production of secondaries is a non-trivial task, because it involves nuclear physics interactions at energies, where no rigorous theories exist to describe them. The goal of this review is to provide a comprehensive overview of various aspects in modeling the physics processes for range verification with secondary particles produced in proton, carbon, and heavier ion irradiation. We discuss electromagnetic and nuclear interactions of charged hadrons in matter, which is followed by a summary of some widely used MC codes in hadron therapy. Then, we describe selected examples of how these codes have been validated and used in three range verification techniques: PET, prompt gamma, and charged particle detection. We include research studies and clinically applied methods. For each of the techniques, we point out advantages and disadvantages, as well as clinical challenges still to be addressed, focusing on MC simulation aspects. PMID:26217586

Single-slit electron diffraction with Aharonov-Bohm phase: Feynman's thought experiment with quantum point contacts.

PubMed

Khatua, Pradip; Bansal, Bhavtosh; Shahar, Dan

2014-01-10

In a "thought experiment," now a classic in physics pedagogy, Feynman visualizes Young's double-slit interference experiment with electrons in magnetic field. He shows that the addition of an Aharonov-Bohm phase is equivalent to shifting the zero-field wave interference pattern by an angle expected from the Lorentz force calculation for classical particles. We have performed this experiment with one slit, instead of two, where ballistic electrons within two-dimensional electron gas diffract through a small orifice formed by a quantum point contact (QPC). As the QPC width is comparable to the electron wavelength, the observed intensity profile is further modulated by the transverse waveguide modes present at the injector QPC. Our experiments open the way to realizing diffraction-based ideas in mesoscopic physics.

Balance of dark and luminous mass in rotating galaxies.

PubMed

McGaugh, Stacy S

2005-10-21

A fine balance between dark and baryonic mass is observed in spiral galaxies. As the contribution of the baryons to the total rotation velocity increases, the contribution of the dark matter decreases by a compensating amount. This poses a fine-tuning problem for galaxy formation models, and may point to new physics for dark matter particles or even a modification of gravity.

Derivation of the Biot-Savart Law from Ampere's Law Using the Displacement Current

ERIC Educational Resources Information Center

Buschauer, Robert

2013-01-01

The equation describing the magnetic field due to a single, nonrelativistic charged particle moving at constant velocity is often referred to as the "Biot-Savart law for a point charge." Introductory calculus-based physics books usually state this law without proof. Advanced texts often present it either without proof or as a special…

Pulse Shape Discrimination in the MAJORANA DEMONSTRATOR

NASA Astrophysics Data System (ADS)

Haufe, Christopher; Majorana Collaboration

2017-09-01

The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium p-type point contact detectors totaling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. A large effort is underway to analyze the data currently being taken by the DEMONSTRATOR. Key components of this effort are analysis tools that allow for pulse shape discrimination-techniques that significantly reduce background levels in the neutrinoless double-beta decay region of interest. These tools are able to identify and reject multi-site events from Compton scattering as well as events from alpha particle interactions. This work serves as an overview for these analysis tools and highlights the unique advantages that the HPGe p-type point contact detector provides to pulse shape discrimination. This material is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.

Cloud-In-Cell modeling of shocked particle-laden flows at a ``SPARSE'' cost

NASA Astrophysics Data System (ADS)

Taverniers, Soren; Jacobs, Gustaaf; Sen, Oishik; Udaykumar, H. S.

2017-11-01

A common tool for enabling process-scale simulations of shocked particle-laden flows is Eulerian-Lagrangian Particle-Source-In-Cell (PSIC) modeling where each particle is traced in its Lagrangian frame and treated as a mathematical point. Its dynamics are governed by Stokes drag corrected for high Reynolds and Mach numbers. The computational burden is often reduced further through a ``Cloud-In-Cell'' (CIC) approach which amalgamates groups of physical particles into computational ``macro-particles''. CIC does not account for subgrid particle fluctuations, leading to erroneous predictions of cloud dynamics. A Subgrid Particle-Averaged Reynolds-Stress Equivalent (SPARSE) model is proposed that incorporates subgrid interphase velocity and temperature perturbations. A bivariate Gaussian source distribution, whose covariance captures the cloud's deformation to first order, accounts for the particles' momentum and energy influence on the carrier gas. SPARSE is validated by conducting tests on the interaction of a particle cloud with the accelerated flow behind a shock. The cloud's average dynamics and its deformation over time predicted with SPARSE converge to their counterparts computed with reference PSIC models as the number of Gaussians is increased from 1 to 16. This work was supported by AFOSR Grant No. FA9550-16-1-0008.

Polyhydroxy surfactants for the formulation of lipid nanoparticles (SLN and NLC): effects on size, physical stability and particle matrix structure.

PubMed

Kovacevic, A; Savic, S; Vuleta, G; Müller, R H; Keck, C M

2011-03-15

The two polyhydroxy surfactants polyglycerol 6-distearate (Plurol(®)Stearique WL1009 - (PS)) and caprylyl/capryl glucoside (Plantacare(®) 810 - (PL)) are a class of PEG-free stabilizers, made from renewable resources. They were investigated for stabilization of aqueous solid lipid nanoparticle (SLN) and nanostructured lipid carrier (NLC) dispersions. Production was performed by high pressure homogenization, analysis by photon correlation spectroscopy (PCS), laser diffraction (LD), zeta potential measurements and differential scanning calorimetry (DSC). Particles were made from Cutina CP as solid lipid only (SLN) and its blends with Miglyol 812 (NLC, the blends containing increasing amounts of oil from 20% to 60%). The obtained particle sizes were identical for both surfactants, about 200 nm with polydispersity indices below 0.20 (PCS), and unimodal size distribution (LD). All dispersions with both surfactants were physically stable for 3 months at room temperature, but Plantacare (PL) showing a superior stability. The melting behaviour and crystallinity of bulk lipids/lipid blends were compared to the nanoparticles. Both were lower for the nanoparticles. The crystallinity of dispersions stabilized with PS was higher, the zeta potential decreased with storage time associated with this higher crystallinity, and leading to a few, but negligible larger particles. The lower crystallinity particles stabilized with PL remained unchanged in zeta potential (about -50 mV) and in size. These data show that surfactants have a distinct influence on the particle matrix structure (and related stability and drug loading), to which too little attention was given by now. Despite being from the same surfactant class, the differences on the structure are pronounced. They are attributed to the hydrophobic-lipophilic tail structure with one-point anchoring in the interface (PL), and the loop conformation of PS with two hydrophobic anchor points, i.e. their molecular structure and its interaction with the matrix surface and matrix bulk. Analysis of the effects of the surfactants on the particle matrix structure could potentially be used to further optimization of stability, drug loading and may be drug release. Copyright © 2011 Elsevier B.V. All rights reserved.

Characterizing the spatio-temporal and energy-dependent response of riometer absorption to particle precipitation

NASA Astrophysics Data System (ADS)

Kellerman, Adam; Makarevich, Roman; Spanswick, Emma; Donovan, Eric; Shprits, Yuri

2016-07-01

Energetic electrons in the 10's of keV range precipitate to the upper D- and lower E-region ionosphere, and are responsible for enhanced ionization. The same particles are important in the inner magnetosphere, as they provide a source of energy for waves, and thus relate to relativistic electron enhancements in Earth's radiation belts.In situ observations of plasma populations and waves are usually limited to a single point, which complicates temporal and spatial analysis. Also, the lifespan of satellite missions is often limited to several years which does not allow one to infer long-term climatology of particle precipitation, important for affecting ionospheric conditions at high latitudes. Multi-point remote sensing of the ionospheric plasma conditions can provide a global view of both ionospheric and magnetospheric conditions, and the coupling between magnetospheric and ionospheric phenomena can be examined on time-scales that allow comprehensive statistical analysis. In this study we utilize multi-point riometer measurements in conjunction with in situ satellite data, and physics-based modeling to investigate the spatio-temporal and energy-dependent response of riometer absorption. Quantifying this relationship may be a key to future advancements in our understanding of the complex D-region ionosphere, and may lead to enhanced specification of auroral precipitation both during individual events and over climatological time-scales.

BOOK REVIEW: The Odd Quantum

NASA Astrophysics Data System (ADS)

Treiman, Sam

2003-07-01

This is an enjoyable book by a particle physicist of some distinction, who wrote several books on the theoretical aspects of his subject. He died soon after the book was finished. This book would seem a splendid tribute to his memory. The first five chapters are an excellent introduction to quantum mechanics from the viewpoint of a particle physicist. (A solid state physicist might include some other topics.) The next three chapters give some feeling for the excitement of particle physics and describe some of the zoo of curious creatures discovered in the depths of particle accelerators, and the forces between them: strong, electromagnetic and weak. The final chapter, 'Quantum Fields', is a tour de force. The author has a light touch and a pleasant sense of humour. He does not attempt to explain everything he mentions, but he makes it very clear when he does not. These points are beautifully illustrated by the following extract from the final chapter (p 245). 'It was said above that virtual particles come into play when the real collision ingredients are all close together. In fact, virtual particles are always in play. Even a single real particle, moving along in isolation, can emit and reabsorb virtual particles over and over again. This has the effect of shifting the physical mass of the particle away from the 'bare' value that entered into the Hamiltonian. That shift inevitably turns out to be slightly infinite, and there is a whole technology for isolating and redefining away this and a few other infinities that are characteristic of renormalisable quantum field theories. But we forebear to pursue these delicacies any further here.' I particularly like 'slightly infinite'. The publisher's blurb describes this book as being suitable for popular science readers. It is not. Its level of mathematics would make it very heavy going for anyone who had not taken at least one course in mathematics at university. This is a book which can be strongly recommended as a supplementary text for undergraduates studying quantum mechanics, and also as a book for professional physicists who wish to obtain an up-to-date description and explanation of particle physics. It ought to be in every library. P Borcherds

Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

2017-12-01

Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

Raman Spectroscopy of Single Light-Absorbing Carbonaceous Particles Levitated in Air Using an Annular Laser Beam.

PubMed

Uraoka, Masaru; Maegawa, Keisuke; Ishizaka, Shoji

2017-12-05

A laser trapping technique is a powerful means to investigate the physical and chemical properties of single aerosol particles in a noncontact manner. However, optical trapping of strongly light-absorbing particles such as black carbon or soot is quite difficult because the repulsive force caused by heat is orders of magnitude larger than the attractive force of radiation pressure. In this study, a laser trapping and Raman microspectroscopy system using an annular laser beam was constructed to achieve noncontact levitation of single light-absorbing particles in air. Single acetylene carbon black or candle soot particles were arbitrarily selected with a glass capillary connected to a three-axis oil hydraulic micromanipulator and introduced into a minute space surrounded by a repulsive force at the focal point of an objective lens. Using the developed system, we achieved optical levitation of micrometer-sized carbonaceous particles and observation of their Raman spectra in air. Furthermore, we demonstrated in situ observations of changes in the morphology and chemical composition of optically trapped carbonaceous particles in air, which were induced by heterogeneous oxidation reactions with ozone and hydroxyl radicals.

Direct and Indirect Dark Matter Detection in Gauge Theories (in Portuguese)

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

Queiroz, Farinaldo

The Dark matter (DM) problem constitutes a key question at the interface among Particle Physics, Astrophysics and Cosmology. The observational data which have been accumulated in the last years point to an existence of non baryonic amount of DM. Since the Standard Model (SM) does not provide any candidate for such non-baryonic DM, the evidence of DM is a major indication for new physics beyond the SM. We will study in this work one of the most popular DM candidates, the so called WIMPs (Weakly Interacting Massive Particles) from a direct and indirect detection perspective. In order to approach themore » direct and indirect dection of DM in the context of Particle Physics in a more pedagogic way, we will begin our discussion talking about a minimal extension of the SM. Later we will work on the subject in a 3-3-1 model. Next, we will study the role of WIMPs in the Big Bang Nucleosynthesis. Lastly, we will look for indirect DM signals in the center of our galaxy using the NASA Satellite, called Fermi-LAT. Through a comprehensive analysis of the data events observed by Fermi-LAT and some background models, we will constrain the dark matter annihilation cross section for several annihilation channels and dark matter halo profiles.« less

Comparison of Two Serologically Distinct Ribonucleic Acid Bacteriophages I. Properties of the Viral Particles

PubMed Central

Overby, L. R.; Barlow, G. H.; Doi, R. H.; Jacob, Monique; Spiegelman, S.

1966-01-01

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. I. Properties of the viral particle. J. Bacteriol. 91:442–448. 1966.—Two ribonucleic acid (RNA) coliphages, MS-2 and Qβ, have been characterized physically and serologically. MS-2 has an S20, w value of 79, a molecular weight of 3.6 × 106, a density of 1.422, and pH 3.9 as its isoelectric point. Qβ has an S20, w of 84, a molecular weight of 4.2 × 106, a density of 1.439, and an isoelectric point at pH 5.3. One host (Escherichia coli A-19) permits a distinction between the two on the basis of a marked difference in plaque size. They are distinct immunochemically, no serological cross-reaction being detectable. Images PMID:5903109

Random Walks in a One-Dimensional Lévy Random Environment

NASA Astrophysics Data System (ADS)

Bianchi, Alessandra; Cristadoro, Giampaolo; Lenci, Marco; Ligabò, Marilena

2016-04-01

We consider a generalization of a one-dimensional stochastic process known in the physical literature as Lévy-Lorentz gas. The process describes the motion of a particle on the real line in the presence of a random array of marked points, whose nearest-neighbor distances are i.i.d. and long-tailed (with finite mean but possibly infinite variance). The motion is a continuous-time, constant-speed interpolation of a symmetric random walk on the marked points. We first study the quenched random walk on the point process, proving the CLT and the convergence of all the accordingly rescaled moments. Then we derive the quenched and annealed CLTs for the continuous-time process.

Compact and controlled microfluidic mixing and biological particle capture

NASA Astrophysics Data System (ADS)

Ballard, Matthew; Owen, Drew; Mills, Zachary Grant; Hesketh, Peter J.; Alexeev, Alexander

2016-11-01

We use three-dimensional simulations and experiments to develop a multifunctional microfluidic device that performs rapid and controllable microfluidic mixing and specific particle capture. Our device uses a compact microfluidic channel decorated with magnetic features. A rotating magnetic field precisely controls individual magnetic microbeads orbiting around the features, enabling effective continuous-flow mixing of fluid streams over a compact mixing region. We use computer simulations to elucidate the underlying physical mechanisms that lead to effective mixing and compare them with experimental mixing results. We study the effect of various system parameters on microfluidic mixing to design an efficient micromixer. We also experimentally and numerically demonstrate that orbiting microbeads can effectively capture particles transported by the fluid, which has major implications in pre-concentration and detection of biological particles including various cells and bacteria, with applications in areas such as point-of-care diagnostics, biohazard detection, and food safety. Support from NSF and USDA is gratefully acknowledged.

Perpetual Points: New Tool for Localization of Coexisting Attractors in Dynamical Systems

NASA Astrophysics Data System (ADS)

Dudkowski, Dawid; Prasad, Awadhesh; Kapitaniak, Tomasz

Perpetual points (PPs) are special critical points for which the magnitude of acceleration describing the dynamics drops to zero, while the motion is still possible (stationary points are excluded), e.g. considering the motion of the particle in the potential field, at perpetual point, it has zero acceleration and nonzero velocity. We show that using PPs we can trace all the stable fixed points in the system, and that the structure of trajectories leading from former points to stable equilibria may be similar to orbits obtained from unstable stationary points. Moreover, we argue that the concept of perpetual points may be useful in tracing unexpected attractors (hidden or rare attractors with small basins of attraction). We show potential applicability of this approach by analyzing several representative systems of physical significance, including the damped oscillator, pendula, and the Henon map. We suggest that perpetual points may be a useful tool for localizing coexisting attractors in dynamical systems.

Measurement and Ontology: What Kind of Evidence Can We Have for Quantum Fields?

NASA Astrophysics Data System (ADS)

Falkenburg, Brigitte

In the following, I deal with the ontology of quantum field theory (QFT) from a Kantian point of view, in terms of parts of empirical reality and their relations. In contradistinction to a formal ontology of QFT that is based primarily on the formal structure of the theory, I focus on the ways in which quantum fields can be measured, and on the structural features of empirical reality to which these measurements give rise. To approach the ontology of quantum fields in terms of measurement results in two paradoxes. First, ontology is about the structure of independent entities which belong to the furniture of the world, but measurements rely on interaction. Second, experimental evidence for quantum field theories is mainly based on particle tracks and other local phenomena. Thus, what kind of evidence can we have for the field structure of quantum fields? My paper attempts to unravel these paradoxes in the following steps. First, I give a rough sketch of the appearances of particle physics, the kinds of experimental evidence which count as tests of quantum electrodynamcs (QED) and the standard model of particle physics (1). In an intermezzo on Kant's view of scientific experience, I explain in which terms we might conceive of empirical reality beyond the claims of strict empiricism (2). Finally, I apply these ideas to the appearances of particle physics and suggest that they commit us to a relational ontology of QFT (3).

50 years of CP violation — What have we learned?

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

McKellar, Bruce H. J.

Early after the discovery of CP violation, the explanation of how the Standard Model of particle physics could allow CP violation was quickly given, but it took many years for the original observation to be unequivocally explained on that basis. It was also proposed that this observation opened up the possibility that we could now explain the fact that the universe is made of matter. Remarkably, 50 years later we have no evidence in particle physics that there is any CP violation except that of the Kobayashi Maskawa mechanism of the standard model. Yet we fail completely to explain themore » baryon asymmetry of the Universe through that mechanism. After reviewing the main points in the history I describe the present experimental attempts to find CP violation beyond the standard model, and explain the theoretical attempts to explain the matter in the Universe.« less

Particle acceleration in explosive relativistic reconnection events and Crab Nebula gamma-ray flares

NASA Astrophysics Data System (ADS)

Lyutikov, Maxim; Komissarov, Serguei; Sironi, Lorenzo

2018-04-01

We develop a model of gamma-ray flares of the Crab Nebula resulting from the magnetic reconnection events in a highly magnetised relativistic plasma. We first discuss physical parameters of the Crab Nebula and review the theory of pulsar winds and termination shocks. We also review the principle points of particle acceleration in explosive reconnection events [Lyutikov et al., J. Plasma Phys., vol. 83(6), p. 635830601 (2017a); J. Plasma Phys., vol. 83(6), p. 635830602 (2017b)]. It is required that particles producing flares are accelerated in highly magnetised regions of the nebula. Flares originate from the poleward regions at the base of the Crab's polar outflow, where both the magnetisation and the magnetic field strength are sufficiently high. The post-termination shock flow develops macroscopic (not related to the plasma properties on the skin-depth scale) kink-type instabilities. The resulting large-scale magnetic stresses drive explosive reconnection events on the light-crossing time of the reconnection region. Flares are produced at the initial stage of the current sheet development, during the X-point collapse. The model has all the ingredients needed for Crab flares: natural formation of highly magnetised regions, explosive dynamics on the light travel time, development of high electric fields on macroscopic scales and acceleration of particles to energies well exceeding the average magnetic energy per particle.

RIP-REMOTE INTERACTIVE PARTICLE-TRACER

NASA Technical Reports Server (NTRS)

Rogers, S. E.

1994-01-01

Remote Interactive Particle-tracing (RIP) is a distributed-graphics program which computes particle traces for computational fluid dynamics (CFD) solution data sets. A particle trace is a line which shows the path a massless particle in a fluid will take; it is a visual image of where the fluid is going. The program is able to compute and display particle traces at a speed of about one trace per second because it runs on two machines concurrently. The data used by the program is contained in two files. The solution file contains data on density, momentum and energy quantities of a flow field at discrete points in three-dimensional space, while the grid file contains the physical coordinates of each of the discrete points. RIP requires two computers. A local graphics workstation interfaces with the user for program control and graphics manipulation, and a remote machine interfaces with the solution data set and performs time-intensive computations. The program utilizes two machines in a distributed mode for two reasons. First, the data to be used by the program is usually generated on the supercomputer. RIP avoids having to convert and transfer the data, eliminating any memory limitations of the local machine. Second, as computing the particle traces can be computationally expensive, RIP utilizes the power of the supercomputer for this task. Although the remote site code was developed on a CRAY, it is possible to port this to any supercomputer class machine with a UNIX-like operating system. Integration of a velocity field from a starting physical location produces the particle trace. The remote machine computes the particle traces using the particle-tracing subroutines from PLOT3D/AMES, a CFD post-processing graphics program available from COSMIC (ARC-12779). These routines use a second-order predictor-corrector method to integrate the velocity field. Then the remote program sends graphics tokens to the local machine via a remote-graphics library. The local machine interprets the graphics tokens and draws the particle traces. The program is menu driven. RIP is implemented on the silicon graphics IRIS 3000 (local workstation) with an IRIX operating system and on the CRAY2 (remote station) with a UNICOS 1.0 or 2.0 operating system. The IRIS 4D can be used in place of the IRIS 3000. The program is written in C (67%) and FORTRAN 77 (43%) and has an IRIS memory requirement of 4 MB. The remote and local stations must use the same user ID. PLOT3D/AMES unformatted data sets are required for the remote machine. The program was developed in 1988.

Quantum phases for a charged particle and electric/magnetic dipole in an electromagnetic field

NASA Astrophysics Data System (ADS)

Kholmetskii, Alexander; Yarman, Tolga

2017-11-01

We point out that the known quantum phases for an electric/magnetic dipole moving in an electromagnetic field must be composed from more fundamental quantum phases emerging for moving elementary charges. Using this idea, we have found two new fundamental quantum phases, next to the known magnetic and electric Aharonov-Bohm phases, and discuss their general properties and physical meaning.

Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point

NASA Astrophysics Data System (ADS)

Hong, Tao; Matsumoto, Masashige; Qiu, Yiming; Chen, Wangchun; Gentile, Thomas R.; Watson, Shannon; Awwadi, Firas F.; Turnbull, Mark M.; Dissanayake, Sachith E.; Agrawal, Harish; Toft-Petersen, Rasmus; Klemke, Bastian; Coester, Kris; Schmidt, Kai P.; Tennant, David A.

2017-07-01

Spontaneous symmetry-breaking quantum phase transitions play an essential role in condensed-matter physics. The collective excitations in the broken-symmetry phase near the quantum critical point can be characterized by fluctuations of phase and amplitude of the order parameter. The phase oscillations correspond to the massless Nambu-Goldstone modes whereas the massive amplitude mode, analogous to the Higgs boson in particle physics, is prone to decay into a pair of low-energy Nambu-Goldstone modes in low dimensions. Especially, observation of a Higgs amplitude mode in two dimensions is an outstanding experimental challenge. Here, using inelastic neutron scattering and applying the bond-operator theory, we directly and unambiguously identify the Higgs amplitude mode in a two-dimensional S = 1/2 quantum antiferromagnet C9H18N2CuBr4 near a quantum critical point in two dimensions. Owing to an anisotropic energy gap, it kinematically prevents such decay and the Higgs amplitude mode acquires an infinite lifetime.

Towards a fully kinetic 3D electromagnetic particle-in-cell model of streamer formation and dynamics in high-pressure electronegative gases

NASA Astrophysics Data System (ADS)

Rose, D. V.; Welch, D. R.; Clark, R. E.; Thoma, C.; Zimmerman, W. R.; Bruner, N.; Rambo, P. K.; Atherton, B. W.

2011-09-01

Streamer and leader formation in high pressure devices is dynamic process involving a broad range of physical phenomena. These include elastic and inelastic particle collisions in the gas, radiation generation, transport and absorption, and electrode interactions. Accurate modeling of these physical processes is essential for a number of applications, including high-current, laser-triggered gas switches. Towards this end, we present a new 3D implicit particle-in-cell simulation model of gas breakdown leading to streamer formation in electronegative gases. The model uses a Monte Carlo treatment for all particle interactions and includes discrete photon generation, transport, and absorption for ultra-violet and soft x-ray radiation. Central to the realization of this fully kinetic particle treatment is an algorithm that manages the total particle count by species while preserving the local momentum distribution functions and conserving charge [D. R. Welch, T. C. Genoni, R. E. Clark, and D. V. Rose, J. Comput. Phys. 227, 143 (2007)]. The simulation model is fully electromagnetic, making it capable of following, for example, the evolution of a gas switch from the point of laser-induced localized breakdown of the gas between electrodes through the successive stages of streamer propagation, initial electrode current connection, and high-current conduction channel evolution, where self-magnetic field effects are likely to be important. We describe the model details and underlying assumptions used and present sample results from 3D simulations of streamer formation and propagation in SF6.

HEPData: a repository for high energy physics data

NASA Astrophysics Data System (ADS)

Maguire, Eamonn; Heinrich, Lukas; Watt, Graeme

2017-10-01

The Durham High Energy Physics Database (HEPData) has been built up over the past four decades as a unique open-access repository for scattering data from experimental particle physics papers. It comprises data points underlying several thousand publications. Over the last two years, the HEPData software has been completely rewritten using modern computing technologies as an overlay on the Invenio v3 digital library framework. The software is open source with the new site available at https://hepdata.net now replacing the previous site at http://hepdata.cedar.ac.uk. In this write-up, we describe the development of the new site and explain some of the advantages it offers over the previous platform.

Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

NASA Astrophysics Data System (ADS)

Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

2017-02-01

Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

Spatial averaging of a dissipative particle dynamics model for active suspensions

NASA Astrophysics Data System (ADS)

Panchenko, Alexander; Hinz, Denis F.; Fried, Eliot

2018-03-01

Starting from a fine-scale dissipative particle dynamics (DPD) model of self-motile point particles, we derive meso-scale continuum equations by applying a spatial averaging version of the Irving-Kirkwood-Noll procedure. Since the method does not rely on kinetic theory, the derivation is valid for highly concentrated particle systems. Spatial averaging yields stochastic continuum equations similar to those of Toner and Tu. However, our theory also involves a constitutive equation for the average fluctuation force. According to this equation, both the strength and the probability distribution vary with time and position through the effective mass density. The statistics of the fluctuation force also depend on the fine scale dissipative force equation, the physical temperature, and two additional parameters which characterize fluctuation strengths. Although the self-propulsion force entering our DPD model contains no explicit mechanism for aligning the velocities of neighboring particles, our averaged coarse-scale equations include the commonly encountered cubically nonlinear (internal) body force density.

From the neutron to three light neutrino species: Some highlights from sixty years of particle physics

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

Goldhaber, Gerson

1990-07-05

I consider the beginning to modern particle physics to be in 1932--33, when James Chadwick discovered the neutron at Cambridge, England, and Carl Anderson discovered the positron in Pasadena, California. I leave out the discoveries of the electron by J. J. Thomson, the nucleus and the proton by Ernest Rutherford, as well as the photon introduced by Albert Einstein and the neutrino as hypothesized by Wolfgang Pauli, as having occurred before my time.'' I was thus able to follow -- and sometimes participate in -- all the developments of modern particle physics. The story I will tell is as themore » unfolding of the field looked; to me -- an experimental particle physicists. As with Rashomon, this is as I see it. To get a different point of view, and no doubt there are many, you need different observer. One might ask, what did I know about physics in the 1930s, anyway It so happens that I did hear abut Chadwick's discovery at the time, mainly because my brother Maurice was working with him in 1934 on the photo-disintegration of the deuteron, and on the first good measurement of the neutron mass. I will concentrate on the thirty years, 1930 to 1960 which includes Dick Dalitz' important early contributions. I will then skip most of the next thirty years for lack of time, and end up with the study of the Z{sup 0} in e{sup +}e{sup {minus}} annihilation. For more details, and explicit references to published papers, I will refer the reader to a recent book by Robert Cahn and myself.« less

Inner space/outer space - The interface between cosmology and particle physics

NASA Astrophysics Data System (ADS)

Kolb, Edward W.; Turner, Michael S.; Lindley, David; Olive, Keith; Seckel, David

A collection of papers covering the synthesis between particle physics and cosmology is presented. The general topics addressed include: standard models of particle physics and cosmology; microwave background radiation; origin and evolution of large-scale structure; inflation; massive magnetic monopoles; supersymmetry, supergravity, and quantum gravity; cosmological constraints on particle physics; Kaluza-Klein cosmology; and future directions and connections in particle physics and cosmology.

Belle II silicon vertex detector

NASA Astrophysics Data System (ADS)

Adamczyk, K.; Aihara, H.; Angelini, C.; Aziz, T.; Babu, V.; Bacher, S.; Bahinipati, S.; Barberio, E.; Baroncelli, Ti.; Baroncelli, To.; Basith, A. K.; Batignani, G.; Bauer, A.; Behera, P. K.; Bergauer, T.; Bettarini, S.; Bhuyan, B.; Bilka, T.; Bosi, F.; Bosisio, L.; Bozek, A.; Buchsteiner, F.; Casarosa, G.; Ceccanti, M.; Červenkov, D.; Chendvankar, S. R.; Dash, N.; Divekar, S. T.; Doležal, Z.; Dutta, D.; Enami, K.; Forti, F.; Friedl, M.; Hara, K.; Higuchi, T.; Horiguchi, T.; Irmler, C.; Ishikawa, A.; Jeon, H. B.; Joo, C. W.; Kandra, J.; Kang, K. H.; Kato, E.; Kawasaki, T.; Kodyš, P.; Kohriki, T.; Koike, S.; Kolwalkar, M. M.; Kvasnička, P.; Lanceri, L.; Lettenbicher, J.; Maki, M.; Mammini, P.; Mayekar, S. N.; Mohanty, G. B.; Mohanty, S.; Morii, T.; Nakamura, K. R.; Natkaniec, Z.; Negishi, K.; Nisar, N. K.; Onuki, Y.; Ostrowicz, W.; Paladino, A.; Paoloni, E.; Park, H.; Pilo, F.; Profeti, A.; Rashevskaya, I.; Rao, K. K.; Rizzo, G.; Rozanska, M.; Sandilya, S.; Sasaki, J.; Sato, N.; Schultschik, S.; Schwanda, C.; Seino, Y.; Shimizu, N.; Stypula, J.; Suzuki, J.; Tanaka, S.; Tanida, K.; Taylor, G. N.; Thalmeier, R.; Thomas, R.; Tsuboyama, T.; Uozumi, S.; Urquijo, P.; Vitale, L.; Volpi, M.; Watanuki, S.; Watson, I. J.; Webb, J.; Wiechczynski, J.; Williams, S.; Würkner, B.; Yamamoto, H.; Yin, H.; Yoshinobu, T.; Belle II SVD Collaboration

2016-09-01

The Belle II experiment at the SuperKEKB collider in Japan is designed to indirectly probe new physics using approximately 50 times the data recorded by its predecessor. An accurate determination of the decay-point position of subatomic particles such as beauty and charm hadrons as well as a precise measurement of low-momentum charged particles will play a key role in this pursuit. These will be accomplished by an inner tracking device comprising two layers of pixelated silicon detector and four layers of silicon vertex detector based on double-sided microstrip sensors. We describe herein the design, prototyping and construction efforts of the Belle-II silicon vertex detector.

Fokker-Planck description of electron and photon transport in homogeneous media

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

Akcasu, A.Z.; Holloway, J.P.

1997-06-01

Starting from a Fokker-Planck description of particle transport, which is valid when the scattering is forwardly peaked and the energy change in scattering is small, we systematically obtain an approximate diffusionlike equation for the particle density by eliminating the direction variable {bold {cflx {Omega}}} with an elimination scheme based on Zwanzig{close_quote}s projection operator formalism in the interaction representation. The elimination procedure closely follows one described by Grigolini and Marchesoni [in {ital Memory Function Approaches to Stochastic Problems in Condensed Matter}, edited by Myron W. Evans, Paolo Grigolini, and Guiseppe P. Parravicini, Advances in Physical Chemistry, Vol. 62 (Wiley-Interscience, New York,more » 1985), Chap. II, p. 29], but with a different projection operator. The resulting diffusion equation is correct up to the second order in the coupling operator between the particle direction and position variable. The diffusion coefficients and mobility in the resulting diffusion equation depend on the initial distribution of the particles in direction and on the path length traveled by the particles. The full solution is obtained for a monoenergetic and monodirectional pulsed point source of particles in an infinite homogeneous medium. This solution is used to study the penetration and the transverse and longitudinal spread of the particles as they are transported through the medium. Application to diffusive wave spectroscopy in calculating the path-length distribution of photons, as well as application to dose calculations in tissue due to an electron beam are mentioned. {copyright} {ital 1997} {ital The American Physical Society}« less

First observation of the Cabibbo suppressed decay B meson going to D meson kaon

NASA Astrophysics Data System (ADS)

Soffer, Abner

1998-10-01

Within the standard model of particles and interactions, CP-violation is due to a single imaginary parameter in the Cabibbo-Kobayashi-Maskawa matrix. Decays of the type B/to DK provide a way to measure the phase γ associated with this parameter, under conditions in which contributions from non-standard model physics are very small. Comparing these measurements with ones which are possibly sensitive to new physics may thus point the way to physics beyond the standard model. We demonstrate that measuring CP-conserving phases in D decays may help enhance the sensitivity of the γ measurement in B/to DK, pending an assumption which we show how to test. Using 3.3×106/ B/bar B pairs collected with the CLEO II detector at the Cornell Electron Storage Ring, we make the first observation of the Cabibbo suppressed decay B+/to /bar D0K+ and find the ratio of branching fractions [/cal B](B+/to /bar D0K+)/[/cal B](B+/to /bar D0π+)=0.055/pm0.014/pm0.005. We also present a review of the cosmological motivation and particle physics aspects of CP-violation measurements, intended for the non-physicist.

Evolutionary dynamics of populations with conflicting interactions: Classification and analytical treatment considering asymmetry and power

NASA Astrophysics Data System (ADS)

Helbing, Dirk; Johansson, Anders

2010-01-01

Evolutionary game theory has been successfully used to investigate the dynamics of systems, in which many entities have competitive interactions. From a physics point of view, it is interesting to study conditions under which a coordination or cooperation of interacting entities will occur, be it spins, particles, bacteria, animals, or humans. Here, we analyze the case, where the entities are heterogeneous, particularly the case of two populations with conflicting interactions and two possible states. For such systems, explicit mathematical formulas will be determined for the stationary solutions and the associated eigenvalues, which determine their stability. In this way, four different types of system dynamics can be classified and the various kinds of phase transitions between them will be discussed. While these results are interesting from a physics point of view, they are also relevant for social, economic, and biological systems, as they allow one to understand conditions for (1) the breakdown of cooperation, (2) the coexistence of different behaviors (“subcultures”), (3) the evolution of commonly shared behaviors (“norms”), and (4) the occurrence of polarization or conflict. We point out that norms have a similar function in social systems that forces have in physics.

Physical chemistry of the H2SO4/HNO3/H2O system - Implications for polar stratospheric clouds

NASA Technical Reports Server (NTRS)

Molina, M. J.; Zhang, R.; Wooldridge, P. J.; Mcmahon, J. R.; Kim, J. E.; Chang, H. Y.; Beyer, K. D.

1993-01-01

Polar stratospheric clouds (PSCs) play a key role in stratospheric ozone depletion. Surface-catalyzed reactions on PSC particles generate chlorine compounds that photolyze readily to yield chlorine radicals, which in turn destroy ozone very efficiently. The most prevalent PSCs form at temperatures several degrees above the ice frost point and are believed to consist of HNO3 hydrates; however, their formation mechanism is unclear. Results of laboratory experiments are presented which indicate that the background stratospheric H2SO4/H2O aerosols provide an essential link in this mechanism: These liquid aerosols absorb significant amounts of HNO3 vapor, leading most likely to the crystallization of nitric acid trihydrate (NAT). The frozen particles then grow to form PSCs by condensation of additional amounts of HNO3 and H2O vapor. Furthermore, reaction probability measurements reveal that the chlorine radical precursors are formed readily at polar stratospheric temperatures not just on NAT and ice crystals, but also on liquid H2SO4 solutions and on solid H2SO4 hydrates. These results imply that the chlorine activation efficiency of the aerosol particles increases rapidly as the temperature approaches the ice frost point regardless of the phase or composition of the particles.

Transition amplitude for two-time physics

NASA Astrophysics Data System (ADS)

Frederico, João E.; Rivelles, Victor O.

2010-07-01

We present the transition amplitude for a particle moving in a space with two times and D space dimensions having an Sp(2,R) local symmetry and an SO(D,2) rigid symmetry. It was obtained from the BRST-BFV quantization with a unique gauge choice. We show that by constraining the initial and final points of this amplitude to lie on some hypersurface of the D+2 space the resulting amplitude reproduces well-known systems in lower dimensions. This work provides an alternative way to derive the effects of two-time physics where all the results come from a single transition amplitude.

Transition amplitude for two-time physics

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

Frederico, Joao E.; Rivelles, Victor O.; Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05314-970, Sao Paulo, SP

2010-07-15

We present the transition amplitude for a particle moving in a space with two times and D space dimensions having an Sp(2,R) local symmetry and an SO(D,2) rigid symmetry. It was obtained from the BRST-BFV quantization with a unique gauge choice. We show that by constraining the initial and final points of this amplitude to lie on some hypersurface of the D+2 space the resulting amplitude reproduces well-known systems in lower dimensions. This work provides an alternative way to derive the effects of two-time physics where all the results come from a single transition amplitude.

The geomagnetically trapped radiation environment: A radiological point of view

NASA Technical Reports Server (NTRS)

Holly, F. E.

1972-01-01

The regions of naturally occurring, geomagnetically trapped radiation are briefly reviewed in terms of physical parameters such as; particle types, fluxes, spectrums, and spatial distributions. The major emphasis is placed upon a description of this environment in terms of the radiobiologically relevant parameters of absorbed dose and dose-rate and a discussion of the radiological implications in terms of the possible impact on space vehicle design and mission planning.

Field theory in superfluid 3He: what are the lessons for particle physics, gravity, and high-temperature superconductivity?

PubMed

Volovik, G E

1999-05-25

There are several classes of homogeneous Fermi systems that are characterized by the topology of the energy spectrum of fermionic quasiparticles: (i) gapless systems with a Fermi surface, (ii) systems with a gap in their spectrum, (iii) gapless systems with topologically stable point nodes (Fermi points), and (iv) gapless systems with topologically unstable lines of nodes (Fermi lines). Superfluid 3He-A and electroweak vacuum belong to the universality class 3. The fermionic quasiparticles (particles) in this class are chiral: they are left-handed or right-handed. The collective bosonic modes of systems of class 3 are the effective gauge and gravitational fields. The great advantage of superfluid 3He-A is that we can perform experiments by using this condensed matter and thereby simulate many phenomena in high energy physics, including axial anomaly, baryoproduction, and magnetogenesis. 3He-A textures induce a nontrivial effective metrics of the space, where the free quasiparticles move along geodesics. With 3He-A one can simulate event horizons, Hawking radiation, rotating vacuum, etc. High-temperature superconductors are believed to belong to class 4. They have gapless fermionic quasiparticles with a "relativistic" spectrum close to gap nodes, which allows application of ideas developed for superfluid 3He-A.

A propulsion-mass tensor coupling in relativistic rocket motion

NASA Astrophysics Data System (ADS)

Brito, Hector Hugo

1998-01-01

Following earlier speculations about antigravity machines and works on the relativistic dynamics of constant and variable rest mass point particles, a mass tensor is found in connection with the closed system consisting of the rocket driven spaceship and its propellant mass, provided a ``solidification'' point other than the system center of mass is considered. Therefore, the mass tensor form depends on whether the system is open or closed, and upon where the ``solidification'' point is located. An alternative propulsion principle is subsequently derived from the tensor mass approach. The new principle, the covariant equivalent of Newton's Third Law for the physical interpretation of the relativistic rocket motion, reads: A spaceship undergoes a propulsion effect when the whole system mass 4-ellipsoid warps.

Point-particle effective field theory I: classical renormalization and the inverse-square potential

NASA Astrophysics Data System (ADS)

Burgess, C. P.; Hayman, Peter; Williams, M.; Zalavári, László

2017-04-01

Singular potentials (the inverse-square potential, for example) arise in many situations and their quantum treatment leads to well-known ambiguities in choosing boundary conditions for the wave-function at the position of the potential's singularity. These ambiguities are usually resolved by developing a self-adjoint extension of the original prob-lem; a non-unique procedure that leaves undetermined which extension should apply in specific physical systems. We take the guesswork out of this picture by using techniques of effective field theory to derive the required boundary conditions at the origin in terms of the effective point-particle action describing the physics of the source. In this picture ambiguities in boundary conditions boil down to the allowed choices for the source action, but casting them in terms of an action provides a physical criterion for their determination. The resulting extension is self-adjoint if the source action is real (and involves no new degrees of freedom), and not otherwise (as can also happen for reasonable systems). We show how this effective-field picture provides a simple framework for understanding well-known renormalization effects that arise in these systems, including how renormalization-group techniques can resum non-perturbative interactions that often arise, particularly for non-relativistic applications. In particular we argue why the low-energy effective theory tends to produce a universal RG flow of this type and describe how this can lead to the phenomenon of reaction catalysis, in which physical quantities (like scattering cross sections) can sometimes be surprisingly large compared to the underlying scales of the source in question. We comment in passing on the possible relevance of these observations to the phenomenon of the catalysis of baryon-number violation by scattering from magnetic monopoles.

Registration procedure for spatial correlation of physical energy deposition of particle irradiation and cellular response utilizing cell-fluorescent ion track hybrid detectors

NASA Astrophysics Data System (ADS)

Niklas, M.; Zimmermann, F.; Schlegel, J.; Schwager, C.; Debus, J.; Jäkel, O.; Abdollahi, A.; Greilich, S.

2016-09-01

The hybrid technology cell-fluorescent ion track hybrid detector (Cell-Fit-HD) enables the investigation of radiation-related cellular events along single ion tracks on the subcellular scale in clinical ion beams. The Cell-Fit-HD comprises a fluorescent nuclear track detector (FNTD, the physical compartment), a device for individual particle detection and a substrate for viable cell-coating, i.e. the biological compartment. To date both compartments have been imaged sequentially in situ by confocal laser scanning microscopy (CLSM). This is yet in conflict with a functional read-out of the Cell-Fit-HD utilizing a fast live-cell imaging of the biological compartment with low phototoxicity on greater time scales. The read-out of the biological from the physical compartment was uncoupled. A read-out procedure was developed to image the cell layer by conventional widefield microscopy whereas the FNTD was imaged by CLSM. Point mapping registration of the confocal and widefield imaging data was performed. Non-fluorescent crystal defects (spinels) visible in both read-outs were used as control point pairs. The accuracy achieved was on the sub-µm scale. The read-out procedure by widefield microscopy does not impair the unique ability of spatial correlation by the Cell-Fit-HD. The uncoupling will enlarge the application potential of the hybrid technology significantly. The registration allows for an ultimate correlation of microscopic physical beam parameters and cell kinetics on greater time scales. The method reported herein will be instrumental for the introduction of a novel generation of compact detectors facilitating biodosimetric research towards high-throughput analysis.

SLAC Library - Online Particle Physics Information

Science.gov Websites

Background Knowledge Particle Physics Lessons and Activities Astronomy and Astrophysics Lessons and Online Particle Physics Information Compiled by Revised: April, 201 7 This annotated list provides a highly selective set of online resources that are useful to the particle physics community. It

Observation of three-component fermions in the topological semimetal molybdenum phosphide.

PubMed

Lv, B Q; Feng, Z-L; Xu, Q-N; Gao, X; Ma, J-Z; Kong, L-Y; Richard, P; Huang, Y-B; Strocov, V N; Fang, C; Weng, H-M; Shi, Y-G; Qian, T; Ding, H

2017-06-29

In quantum field theory, Lorentz invariance leads to three types of fermion-Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Observation of three-component fermions in the topological semimetal molybdenum phosphide

NASA Astrophysics Data System (ADS)

Lv, B. Q.; Feng, Z.-L.; Xu, Q.-N.; Gao, X.; Ma, J.-Z.; Kong, L.-Y.; Richard, P.; Huang, Y.-B.; Strocov, V. N.; Fang, C.; Weng, H.-M.; Shi, Y.-G.; Qian, T.; Ding, H.

2017-06-01

In quantum field theory, Lorentz invariance leads to three types of fermion—Dirac, Weyl and Majorana. Although the existence of Weyl and Majorana fermions as elementary particles in high-energy physics is debated, all three types of fermion have been proposed to exist as low-energy, long-wavelength quasiparticle excitations in condensed-matter systems. The existence of Dirac and Weyl fermions in condensed-matter systems has been confirmed experimentally, and that of Majorana fermions is supported by various experiments. However, in condensed-matter systems, fermions in crystals are constrained by the symmetries of the 230 crystal space groups rather than by Lorentz invariance, giving rise to the possibility of finding other types of fermionic excitation that have no counterparts in high-energy physics. Here we use angle-resolved photoemission spectroscopy to demonstrate the existence of a triply degenerate point in the electronic structure of crystalline molybdenum phosphide. Quasiparticle excitations near a triply degenerate point are three-component fermions, beyond the conventional Dirac-Weyl-Majorana classification, which attributes Dirac and Weyl fermions to four- and two-fold degenerate points, respectively. We also observe pairs of Weyl points in the bulk electronic structure of the crystal that coexist with the three-component fermions. This material thus represents a platform for studying the interplay between different types of fermions. Our experimental discovery opens up a way of exploring the new physics of unconventional fermions in condensed-matter systems.

Two decades of Mexican particle physics at Fermilab

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

Roy Rubinstein

2002-12-03

This report is a view from Fermilab of Mexican particle physics at the Laboratory since about 1980; it is not intended to be a history of Mexican particle physics: that topic is outside the expertise of the writer. The period 1980 to the present coincides with the growth of Mexican experimental particle physics from essentially no activity to its current state where Mexican groups take part in experiments at several of the world's major laboratories. Soon after becoming Fermilab director in 1979, Leon Lederman initiated a program to encourage experimental physics, especially experimental particle physics, in Latin America. At themore » time, Mexico had significant theoretical particle physics activity, but none in experiment. Following a visit by Lederman to UNAM in 1981, a conference ''Panamerican Symposium on Particle Physics and Technology'' was held in January 1982 at Cocoyoc, Mexico, with about 50 attendees from Europe, North America, and Latin America; these included Lederman, M. Moshinsky, J. Flores, S. Glashow, J. Bjorken, and G. Charpak. Among the conference outcomes were four subsequent similar symposia over the next decade, and a formal Fermilab program to aid Latin American physics (particularly particle physics); it also influenced a decision by Mexican physicist Clicerio Avilez to switch from theoretical to experimental particle physics. The first physics collaboration between Fermilab and Mexico was in particle theory. Post-docs Rodrigo Huerta and Jose Luis Lucio spent 1-2 years at Fermilab starting in 1981, and other theorists (including Augusto Garcia, Arnulfo Zepeda, Matias Moreno and Miguel Angel Perez) also spent time at the Laboratory in the 1980s.« less

Traffic Flow of Interacting Self-Driven Particles: Rails and Trails, Vehicles and Vesicles

NASA Astrophysics Data System (ADS)

Chowdhury, Debashish

One common feature of a vehicle, an ant and a kinesin motor is that they all convert chemical energy, derived from fuel or food, into mechanical energy required for their forward movement; such objects have been modelled in recent years as self-driven particles. Cytoskeletal filaments, e.g., microtubules, form a rail network for intra-cellular transport of vesicular cargo by molecular motors like, for example, kinesins. Similarly, ants move along trails while vehicles move along lanes. Therefore, the traffic of vehicles and organisms as well as that of molecular motors can be modelled as systems of interacting self-driven particles; these are of current interest in non-equilibrium statistical mechanics. In this paper we point out the common features of these model systems and emphasize the crucial differences in their physical properties.

Search for new physics with long-lived particles decaying to photons and missing energy in pp collisions at $$ \\sqrt{s}=7 $$ TeV

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

Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.

A search is performed for long-lived neutral particles decaying into a photon and invisible particles. An example of such a signature is the decay of the lightest neutralino with nonzero lifetime into a gravitino and a photon in gauge-mediated supersymmetry, with the neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest. The search uses events containing photons, missing transverse energy, and jets. The impact parameter of the photon relative to the beam-beam collision point can be reconstructed using converted photons. The method is sensitive to lifetimes of the order of 0.1 to 1 ns. The data samplemore » corresponds to an integrated luminosity of 2.23 inverse femtobarns in pp collisions at sqrt(s) = 7 TeV, recorded in the first part of 2011 by the CMS experiment at the LHC. Cross-section limits are presented on pair production for such particles, each of which decays into a photon and invisible particles. The observed 95% confidence level limits vary between 0.11 and 0.21 pb, depending on the neutral particle lifetime.« less

Quantum physics and the beam splitter mystery

NASA Astrophysics Data System (ADS)

Hénault, François

2015-09-01

Optical lossless beam splitters are frequently encountered in fundamental physics experiments regarding the nature of light, including "which-way" determination or the EPR paradox and their measurement apparatus. Although they look as common optical components at first glance, their behaviour remains somewhat mysterious since they apparently exhibit stand-alone particle-like features, and then wave-like characteristics when inserted into a Mach-Zehnder interferometer. In this communication are examined and discussed some basic properties of these beamssplitters, both from a classical optics and quantum physics point of view. Herein the most evident convergences and contradictions are highlighted, and the results of a few emblematic experiments demonstrating photon existence are discussed. Alternative empirical models are also proposed in order to shed light on some remaining issues.

Turning the LHC ring into a new physics search machine

NASA Astrophysics Data System (ADS)

Orava, Risto

2017-03-01

The LHC Collider Ring is proposed to be turned into an ultimate automatic search engine for new physics in four consecutive phases: (1) Searches for heavy particles produced in Central Exclusive Process (CEP): pp → p + X + p based on the existing Beam Loss Monitoring (BLM) system of the LHC; (2) Feasibility study of using the LHC Ring as a gravitation wave antenna; (3) Extensions to the current BLM system to facilitate precise registration of the selected CEP proton exit points from the LHC beam vacuum chamber; (4) Integration of the BLM based event tagging system together with the trigger/data acquisition systems of the LHC experiments to facilitate an on-line automatic search machine for the physics of tomorrow.

Mass composition studies of Ultra High Energy cosmic rays through the measurement of the Muon Production Depths at the Pierre Auger Observatory

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

Collica, Laura

The Pierre Auger Observatory (Auger) in Argentina studies Ultra High Energy Cosmic Rays (UHECRs) physics. The flux of cosmic rays at these energies (above 1018 eV) is very low (less than 100 particle/km2-year) and UHECR properties must be inferred from the measurements of the secondary particles that the cosmic ray primary produces in the atmosphere. These particles cascades are called Extensive Air Showers (EAS) and can be studied at ground by deploying detectors covering large areas. The EAS physics is complex, and the properties of secondary particles depend strongly on the first interaction, which takes place at an energy beyondmore » the ones reached at accelerators. As a consequence, the analysis of UHECRs is subject to large uncertainties and hence many of their properties, in particular their composition, are still unclear. Two complementary techniques are used at Auger to detect EAS initiated by UHE- CRs: a 3000 km2 surface detector (SD) array of water Cherenkov tanks which samples particles at ground level and fluorescence detectors (FD) which collect the ultraviolet light emitted by the de-excitation of nitrogen nuclei in the atmosphere, and can operate only in clear, moonless nights. Auger is the largest cosmic rays detector ever built and it provides high-quality data together with unprecedented statistics. The main goal of this thesis is the measurement of UHECR mass composition using data from the SD of the Pierre Auger Observatory. Measuring the cosmic ray composition at the highest energies is of fundamental importance from the astrophysical point of view, since it could discriminate between different scenarios of origin and propagation of cosmic rays. Moreover, mass composition studies are of utmost importance for particle physics. As a matter of fact, knowing the composition helps in exploring the hadronic interactions at ultra-high energies, inaccessible to present accelerator experiments.« less

Convergence of the Bouguer-Beer law for radiation extinction in particulate media

NASA Astrophysics Data System (ADS)

Frankel, A.; Iaccarino, G.; Mani, A.

2016-10-01

Radiation transport in particulate media is a common physical phenomenon in natural and industrial processes. Developing predictive models of these processes requires a detailed model of the interaction between the radiation and the particles. Resolving the interaction between the radiation and the individual particles in a very large system is impractical, whereas continuum-based representations of the particle field lend themselves to efficient numerical techniques based on the solution of the radiative transfer equation. We investigate radiation transport through discrete and continuum-based representations of a particle field. Exact solutions for radiation extinction are developed using a Monte Carlo model in different particle distributions. The particle distributions are then projected onto a concentration field with varying grid sizes, and the Bouguer-Beer law is applied by marching across the grid. We show that the continuum-based solution approaches the Monte Carlo solution under grid refinement, but quickly diverges as the grid size approaches the particle diameter. This divergence is attributed to the homogenization error of an individual particle across a whole grid cell. We remark that the concentration energy spectrum of a point-particle field does not approach zero, and thus the concentration variance must also diverge under infinite grid refinement, meaning that no grid-converged solution of the radiation transport is possible.

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

Calixto, M., E-mail: calixto@ugr.es; Pérez-Romero, E.

We revise the unireps. of U(2, 2) describing conformal particles with continuous mass spectrum from a many-body perspective, which shows massive conformal particles as compounds of two correlated massless particles. The statistics of the compound (boson/fermion) depends on the helicity h of the massless components (integer/half-integer). Coherent states (CS) of particle-hole pairs (“excitons”) are also explicitly constructed as the exponential action of exciton (non-canonical) creation operators on the ground state of unpaired particles. These CS are labeled by points Z (2×2 complex matrices) on the Cartan-Bergman domain D₄=U(2,2)/U(2)², and constitute a generalized (matrix) version of Perelomov U(1, 1) coherent statesmore » labeled by points z on the unit disk D₁=U(1,1)/U(1)². First, we follow a geometric approach to the construction of CS, orthonormal basis, U(2, 2) generators and their matrix elements and symbols in the reproducing kernel Hilbert space H{sub λ}(D₄) of analytic square-integrable holomorphic functions on D₄, which carries a unitary irreducible representation of U(2, 2) with index λϵN (the conformal or scale dimension). Then we introduce a many-body representation of the previous construction through an oscillator realization of the U(2, 2) Lie algebra generators in terms of eight boson operators with constraints. This particle picture allows us for a physical interpretation of our abstract mathematical construction in the many-body jargon. In particular, the index λ is related to the number 2(λ – 2) of unpaired quanta and to the helicity h = (λ – 2)/2 of each massless particle forming the massive compound.« less

Contact-aware simulations of particulate Stokesian suspensions

NASA Astrophysics Data System (ADS)

Lu, Libin; Rahimian, Abtin; Zorin, Denis

2017-10-01

We present an efficient, accurate, and robust method for simulation of dense suspensions of deformable and rigid particles immersed in Stokesian fluid in two dimensions. We use a well-established boundary integral formulation for the problem as the foundation of our approach. This type of formulation, with a high-order spatial discretization and an implicit and adaptive time discretization, have been shown to be able to handle complex interactions between particles with high accuracy. Yet, for dense suspensions, very small time-steps or expensive implicit solves as well as a large number of discretization points are required to avoid non-physical contact and intersections between particles, leading to infinite forces and numerical instability. Our method maintains the accuracy of previous methods at a significantly lower cost for dense suspensions. The key idea is to ensure interference-free configuration by introducing explicit contact constraints into the system. While such constraints are unnecessary in the formulation, in the discrete form of the problem, they make it possible to eliminate catastrophic loss of accuracy by preventing contact explicitly. Introducing contact constraints results in a significant increase in stable time-step size for explicit time-stepping, and a reduction in the number of points adequate for stability.

LHC vector resonance searches in the t\\overline{t}Z final state

NASA Astrophysics Data System (ADS)

Backović, Mihailo; Flacke, Thomas; Jain, Bithika; Lee, Seung J.

2017-03-01

LHC searches for BSM resonances in l + l - , jj, t\\overline{t} , γγ and VV final states have so far not resulted in discovery of new physics. Current results set lower limits on mass scales of new physics resonances well into the O(1) TeV range, assuming that the new resonance decays dominantly to a pair of Standard Model particles. While the SM pair searches are a vital probe of possible new physics, it is important to re-examine the scope of new physics scenarios probed with such final states. Scenarios where new resonances decay dominantly to final states other than SM pairs, even though well theoretically motivated, lie beyond the scope of SM pair searches. In this paper we argue that LHC searches for (vector) resonances beyond two particle final states would be useful complementary probes of new physics scenarios. As an example, we consider a class of composite Higgs models, and identify specific model parameter points where the color singlet, electrically neutral vector resonance ρ0 decays dominantly not to a pair of SM particles, but to a fermionic top partner T f1 and a top quark, with T f1 → tZ. We show that dominant decays of ρ 0 → T f1 t in the context of Composite Higgs models are possible even when the decay channel to a pair of T f1 is kinematically open. Our analysis deals with scenarios where both m ρ and {m}_T{{}{_f}}{_1} are of O(1) TeV, leading to highly boosted t\\overline{t}Z final state topologies. We show that the particular composite Higgs scenario we consider is discoverable at the LHC13 with as little as 30 fb-1, while being allowed by other existing experimental constraints.

Wave-particle and wave-wave interactions in hot plasmas: a French historical point of view

NASA Astrophysics Data System (ADS)

Laval, Guy; Pesme, Denis; Adam, Jean-Claude

2016-11-01

The first researches on nuclear fusion for energy applications marked the entrance of hot plasmas into the laboratory. It became necessary to understand the behavior of such plasmas and to learn how to manipulate them. Theoreticians and experimentalists, building on the foundations of empirical laws, had to construct this new plasma physics from first principles and to explain the results of more and more complicated experiments. Along this line, two important topics emerged: wave-particle and wave-wave interactions. Here, their history is recalled as it has been lived by a French team from the end of the sixties to the beginning of the twenty-first century.

The electrobrachistochrone

NASA Astrophysics Data System (ADS)

Lipscombe, Trevor C.; Mungan, Carl E.

2018-05-01

The brachistochrone problem consists of finding the track of shortest travel time between given initial and final points for a particle sliding frictionlessly along it under the influence of a given external force field. Solvable variations of the standard example of a uniform gravitational field would be suitable for homework and computer projects by undergraduate physics students studying intermediate mechanics and electromagnetism. An electrobrachistochrone problem is here proposed, in which a charged particle moves along a frictionless track under the influence of its electrostatic force of attraction to an image charge in a grounded conducting plane below the track. The path of least time is found to be a foreshortened cycloid and its properties are investigated analytically and graphically.

Electromagnet Move Down William Floyd Parkway, 6/24/13

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

None

At midnight on Monday, June 24, 2013, a 50-foot-wide, circular electromagnet began the second leg of a 3,200-mile land and sea voyage from Brookhaven National Laboratory in New York to a new home at Fermilab in Illinois. There, scientists will use it to study the properties of muons, subatomic particles that live only 2.2 millionths of a second, and the results could open the door to new realms of particle physics. During this leg, Emmert International transported the electromagnet 10 miles down William Floyd Parkway to the Smith Point Marina, where it was loaded on a barge later in themore » day.« less

Constraining in-medium nucleon-nucleon interactions via nucleus-nucleus reactions

NASA Astrophysics Data System (ADS)

Sammarruca, Francesca; White, Larz

2010-11-01

The nuclear equation of state is a broadly useful tool. Besides being the main input of stellar structure calculations, it allows a direct connection to the physics of nuclei. For instance, an energy functional (such as a mass formula), together with the energy/particle in nuclear matter, can be used to predict nuclear energies and radii [1]. The single-particle properties are also a key point to link infinite nuclear matter and actual nuclei. The parameters of the single-particle potential, in particular the effective mass, enter the calculations of, for instance, in-medium effective cross sections. From the well-known Glauber reaction theory, the total nucleus-nucleus reaction cross section is expressed in terms of the nuclear transparency, which, in turn, depends on the overlap of the nuclear density distributions and the elementary nucleon-nucleon (NN) cross sections. We explore the sensitivity of the reaction calculation to medium modifications of the NN cross sections to estimate the likelihood of constraining the latter through nuclear reactions. Ultimately, we wish to incorporate isospin asymmetry in the reaction model, having in mind connections with rare isotopes. [1] F. Sammarruca, arXiv:1002.00146 [nucl-th]; International Journal of Modern Physics, in press.

Topological framework for local structure analysis in condensed matter

PubMed Central

Lazar, Emanuel A.; Han, Jian; Srolovitz, David J.

2015-01-01

Physical systems are frequently modeled as sets of points in space, each representing the position of an atom, molecule, or mesoscale particle. As many properties of such systems depend on the underlying ordering of their constituent particles, understanding that structure is a primary objective of condensed matter research. Although perfect crystals are fully described by a set of translation and basis vectors, real-world materials are never perfect, as thermal vibrations and defects introduce significant deviation from ideal order. Meanwhile, liquids and glasses present yet more complexity. A complete understanding of structure thus remains a central, open problem. Here we propose a unified mathematical framework, based on the topology of the Voronoi cell of a particle, for classifying local structure in ordered and disordered systems that is powerful and practical. We explain the underlying reason why this topological description of local structure is better suited for structural analysis than continuous descriptions. We demonstrate the connection of this approach to the behavior of physical systems and explore how crystalline structure is compromised at elevated temperatures. We also illustrate potential applications to identifying defects in plastically deformed polycrystals at high temperatures, automating analysis of complex structures, and characterizing general disordered systems. PMID:26460045

Effect of Finite Particle Size on Convergence of Point Particle Models in Euler-Lagrange Multiphase Dispersed Flow

NASA Astrophysics Data System (ADS)

Nili, Samaun; Park, Chanyoung; Haftka, Raphael T.; Kim, Nam H.; Balachandar, S.

2017-11-01

Point particle methods are extensively used in simulating Euler-Lagrange multiphase dispersed flow. When particles are much smaller than the Eulerian grid the point particle model is on firm theoretical ground. However, this standard approach of evaluating the gas-particle coupling at the particle center fails to converge as the Eulerian grid is reduced below particle size. We present an approach to model the interaction between particles and fluid for finite size particles that permits convergence. We use the generalized Faxen form to compute the force on a particle and compare the results against traditional point particle method. We apportion the different force components on the particle to fluid cells based on the fraction of particle volume or surface in the cell. The application is to a one-dimensional model of shock propagation through a particle-laden field at moderate volume fraction, where the convergence is achieved for a well-formulated force model and back coupling for finite size particles. Comparison with 3D direct fully resolved numerical simulations will be used to check if the approach also improves accuracy compared to the point particle model. Work supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, under Contract No. DE-NA0002378.

Dynamic discrete tomography

NASA Astrophysics Data System (ADS)

Alpers, Andreas; Gritzmann, Peter

2018-03-01

We consider the problem of reconstructing the paths of a set of points over time, where, at each of a finite set of moments in time the current positions of points in space are only accessible through some small number of their x-rays. This particular particle tracking problem, with applications, e.g. in plasma physics, is the basic problem in dynamic discrete tomography. We introduce and analyze various different algorithmic models. In particular, we determine the computational complexity of the problem (and various of its relatives) and derive algorithms that can be used in practice. As a byproduct we provide new results on constrained variants of min-cost flow and matching problems.

Summation of power series in particle physics

NASA Astrophysics Data System (ADS)

Fischer, Jan

1999-04-01

The large-order behaviour of power series used in quantum theory (perturbation series and the operator-product expansion) is discussed and relevant summation methods are reviewed. It is emphasised that, in most physically interesting situations, the mere knowledge of the expansion coefficients is not sufficient for a unique determination of the function expanded, and the necessity of some additional, extra-perturbative, input is pointed out. Several possible nonperturbative inputs are suggested. Applications to various problems of quantum chromodynamics are considered. This lecture was presented on the special Memorial Day dedicated to Professor Ryszard R˛czka at this Workshop. The last section is devoted to my personal recollections of this remarkable personality.

Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids.

PubMed

Ploetz, Elizabeth A; Karunaweera, Sadish; Smith, Paul E

2015-01-28

Fluctuation solution theory has provided an alternative view of many liquid mixture properties in terms of particle number fluctuations. The particle number fluctuations can also be related to integrals of the corresponding two body distribution functions between molecular pairs in order to provide a more physical picture of solution behavior and molecule affinities. Here, we extend this type of approach to provide expressions for higher order triplet and quadruplet fluctuations, and thereby integrals over the corresponding distribution functions, all of which can be obtained from available experimental thermodynamic data. The fluctuations and integrals are then determined using the International Association for the Properties of Water and Steam Formulation 1995 (IAPWS-95) equation of state for the liquid phase of pure water. The results indicate small, but significant, deviations from a Gaussian distribution for the molecules in this system. The pressure and temperature dependence of the fluctuations and integrals, as well as the limiting behavior as one approaches both the triple point and the critical point, are also examined.

Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids

NASA Astrophysics Data System (ADS)

Ploetz, Elizabeth A.; Karunaweera, Sadish; Smith, Paul E.

2015-01-01

Fluctuation solution theory has provided an alternative view of many liquid mixture properties in terms of particle number fluctuations. The particle number fluctuations can also be related to integrals of the corresponding two body distribution functions between molecular pairs in order to provide a more physical picture of solution behavior and molecule affinities. Here, we extend this type of approach to provide expressions for higher order triplet and quadruplet fluctuations, and thereby integrals over the corresponding distribution functions, all of which can be obtained from available experimental thermodynamic data. The fluctuations and integrals are then determined using the International Association for the Properties of Water and Steam Formulation 1995 (IAPWS-95) equation of state for the liquid phase of pure water. The results indicate small, but significant, deviations from a Gaussian distribution for the molecules in this system. The pressure and temperature dependence of the fluctuations and integrals, as well as the limiting behavior as one approaches both the triple point and the critical point, are also examined.

The CERN disposal of the FELIX project proposal: some comments on and justification for it.

NASA Astrophysics Data System (ADS)

Bhattacharyya, S.; Roy, D.

1998-12-01

The authors seriously questioned and still continue to question the overemphasised "prospects" in the past of the so-called FELIX project in the domain of ultrahigh-energy astroparticle physics and the optimism that was nurtured around it. This was and is somewhat irrational because there is so far no dearth in the accumulated data for the testing of the models for particle production. But that up to now we failed to build up a really and concretely standard theory of particle production is due to our poverty in outlook and philosophy. The authors picked up and pointed out the very basic down-to-earth observables which even in the available energy range would really suffice to judge the merits and successes of any of the models. That the spirit of FELIX-like proposals might resurrect with just some other name even after the present (and temporary?) setback of the FELIX project remains the point of concern to the authors.

Nonlinear dynamics of charged particles in the magnetotail

NASA Technical Reports Server (NTRS)

Chen, James

1992-01-01

An important region of the earth's magnetosphere is the nightside magnetotail, which is believed to play a significant role in energy storage and release associated with substorms. The magnetotail contains a current sheet which separates regions of oppositely directed magnetic field. Particle motion in the collisionless magnetotail has been a long-standing problem. Recent research from the dynamical point of view has yielded considerable new insights into the fundamental properties of orbits and of particle distribution functions. A new framework of understanding magnetospheric plasma properties is emerging. Some novel predictions based directly on nonlinear dynamics have proved to be robust and in apparent good agreement with observation. The earth's magnetotail may serve as a paradigm, one accessible by in situ observation, of a broad class of boundary regions with embedded current sheets. This article reviews the nonlinear dynamics of charged particles in the magnetotail configuration. The emphasis is on the relationships between the dynamics and physical observables. At the end of the introduction, sections containing basic material are indicated.

Work statistics of charged noninteracting fermions in slowly changing magnetic fields.

PubMed

Yi, Juyeon; Talkner, Peter

2011-04-01

We consider N fermionic particles in a harmonic trap initially prepared in a thermal equilibrium state at temperature β^{-1} and examine the probability density function (pdf) of the work done by a magnetic field slowly varying in time. The behavior of the pdf crucially depends on the number of particles N but also on the temperature. At high temperatures (β≪1) the pdf is given by an asymmetric Laplace distribution for a single particle, and for many particles it approaches a Gaussian distribution with variance proportional to N/β(2). At low temperatures the pdf becomes strongly peaked at the center with a variance that still linearly increases with N but exponentially decreases with the temperature. We point out the consequences of these findings for the experimental confirmation of the Jarzynski equality such as the low probability issue at high temperatures and its solution at low temperatures, together with a discussion of the crossover behavior between the two temperature regimes. ©2011 American Physical Society

Identifying WIMP dark matter from particle and astroparticle data

NASA Astrophysics Data System (ADS)

Bertone, Gianfranco; Bozorgnia, Nassim; Kim, Jong Soo; Liem, Sebastian; McCabe, Christopher; Otten, Sydney; Ruiz de Austri, Roberto

2018-03-01

One of the most promising strategies to identify the nature of dark matter consists in the search for new particles at accelerators and with so-called direct detection experiments. Working within the framework of simplified models, and making use of machine learning tools to speed up statistical inference, we address the question of what we can learn about dark matter from a detection at the LHC and a forthcoming direct detection experiment. We show that with a combination of accelerator and direct detection data, it is possible to identify newly discovered particles as dark matter, by reconstructing their relic density assuming they are weakly interacting massive particles (WIMPs) thermally produced in the early Universe, and demonstrating that it is consistent with the measured dark matter abundance. An inconsistency between these two quantities would instead point either towards additional physics in the dark sector, or towards a non-standard cosmology, with a thermal history substantially different from that of the standard cosmological model.

Constructing the tree-level Yang-Mills S-matrix using complex factorization

NASA Astrophysics Data System (ADS)

Schuster, Philip C.; Toro, Natalia

2009-06-01

A remarkable connection between BCFW recursion relations and constraints on the S-matrix was made by Benincasa and Cachazo in 0705.4305, who noted that mutual consistency of different BCFW constructions of four-particle amplitudes generates non-trivial (but familiar) constraints on three-particle coupling constants — these include gauge invariance, the equivalence principle, and the lack of non-trivial couplings for spins > 2. These constraints can also be derived with weaker assumptions, by demanding the existence of four-point amplitudes that factorize properly in all unitarity limits with complex momenta. From this starting point, we show that the BCFW prescription can be interpreted as an algorithm for fully constructing a tree-level S-matrix, and that complex factorization of general BCFW amplitudes follows from the factorization of four-particle amplitudes. The allowed set of BCFW deformations is identified, formulated entirely as a statement on the three-particle sector, and using only complex factorization as a guide. Consequently, our analysis based on the physical consistency of the S-matrix is entirely independent of field theory. We analyze the case of pure Yang-Mills, and outline a proof for gravity. For Yang-Mills, we also show that the well-known scaling behavior of BCFW-deformed amplitudes at large z is a simple consequence of factorization. For gravity, factorization in certain channels requires asymptotic behavior ~ 1/z2.

Does the presence of cosmic dust influence the displacement of the Earth's Magnetopause?

NASA Astrophysics Data System (ADS)

Mann, I.; Hamrin, M.

2012-04-01

In a recent paper Treumann and Baumjohann propose that dust particles in interplanetary space occasionally cause large compressions of the magnetopause that, in the absence of coronal mass ejections, are difficult to explain by other mechanisms (R.A. Treumann and W. Baumjohann, Ann. Geophys. 30, 119-130, 2012). They suggest that enhanced dust number density raises the contribution of the dust component to the solar wind dynamical pressure and hence to the pressure balance that determines the extension of the magnetopause. They quantify the influence of the dust component in terms of a variation of the magnetopause stagnation point distance. As a possible event to trigger the compressions they propose the encounters with meteoroid dust streams along Earth's orbit. We investigate the conditions under which these compressions may occur. The estimate by Treumann and Baumjohann of the magnetopause variation presupposes that the dust particles have reached solar wind speed. Acceleration by electromagnetic forces is efficient in the solar wind for dust particles that have a sufficiently large ratio of surface charge to mass (Mann et al. Plasma Phys. Contr. Fusion, Vol. 52, 124012, 2010). This applies to small dust particles that contribute little to the total dust mass in meteoroid streams. The major fraction of dust particles that reach high speed in the solar wind are nanometer-sized dust particles that form and are accelerated in the inner solar system (Czechowski and Mann, ApJ, Vol. 714, 89, 2010). Observations suggest that the flux of these nanodust particles near 1 AU is highly time-variable (Meyer-Vernet, et al. Solar Physics, Vol. 256, 463, 2009). We estimate a possible variation of the magnetopause stagnation point distance caused by these nanodust fluxes and by the dust associated to meteoroid streams. We conclude that the Earth's encounters with meteoroid dust streams are not likely to strongly influence the magnetopause according to the proposed effect. We further use the expression for the magnetopause stagnation point distance used by Treumann and Baumjohann to investigate the possible influence of time-variable nanoddust fluxes on the magnetopause.

Inquiring Minds

Science.gov Websites

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Quasicrystals and Quantum Computing

NASA Astrophysics Data System (ADS)

Berezin, Alexander A.

1997-03-01

In Quantum (Q) Computing qubits form Q-superpositions for macroscopic times. One scheme for ultra-fast (Q) computing can be based on quasicrystals. Ultrafast processing in Q-coherent structures (and the very existence of durable Q-superpositions) may be 'consequence' of presence of entire manifold of integer arithmetic (A0, aleph-naught of Georg Cantor) at any 4-point of space-time, furthermore, at any point of any multidimensional phase space of (any) N-particle Q-system. The latter, apart from quasicrystals, can include dispersed and/or diluted systems (Berezin, 1994). In such systems such alleged centrepieces of Q-Computing as ability for fast factorization of long integers can be processed by sheer virtue of the fact that entire infinite pattern of prime numbers is instantaneously available as 'free lunch' at any instant/point. Infinitely rich pattern of A0 (including pattern of primes and almost primes) acts as 'independent' physical effect which directly generates Q-dynamics (and physical world) 'out of nothing'. Thus Q-nonlocality can be ultimately based on instantaneous interconnectedness through ever- the-same structure of A0 ('Platonic field' of integers).

Statistical physics of human cooperation

NASA Astrophysics Data System (ADS)

Perc, Matjaž; Jordan, Jillian J.; Rand, David G.; Wang, Zhen; Boccaletti, Stefano; Szolnoki, Attila

2017-05-01

Extensive cooperation among unrelated individuals is unique to humans, who often sacrifice personal benefits for the common good and work together to achieve what they are unable to execute alone. The evolutionary success of our species is indeed due, to a large degree, to our unparalleled other-regarding abilities. Yet, a comprehensive understanding of human cooperation remains a formidable challenge. Recent research in the social sciences indicates that it is important to focus on the collective behavior that emerges as the result of the interactions among individuals, groups, and even societies. Non-equilibrium statistical physics, in particular Monte Carlo methods and the theory of collective behavior of interacting particles near phase transition points, has proven to be very valuable for understanding counterintuitive evolutionary outcomes. By treating models of human cooperation as classical spin models, a physicist can draw on familiar settings from statistical physics. However, unlike pairwise interactions among particles that typically govern solid-state physics systems, interactions among humans often involve group interactions, and they also involve a larger number of possible states even for the most simplified description of reality. The complexity of solutions therefore often surpasses that observed in physical systems. Here we review experimental and theoretical research that advances our understanding of human cooperation, focusing on spatial pattern formation, on the spatiotemporal dynamics of observed solutions, and on self-organization that may either promote or hinder socially favorable states.

Electrophoresis in ice surface grooves for probing protein affinity to a specific plane of ice crystal.

PubMed

Inagawa, Arinori; Okada, Yusuke; Okada, Tetsuo

2018-06-01

Channel-like grooves are formed on the surface of frozen aqueous sucrose. They are filled with a freeze concentrated solution (FCS) and act as an efficient size-tunable separation field for micro and nanoparticles. The width of the channel can be easily varied by changing the temperature. Because the channel width decreases with decreasing temperature, particles become immobilized due to physical interference from the ice wall when the temperature reaches a threshold point specific to the particle size. Surface modification of particles can add a factor of chemical interaction between the particles and ice walls. In this study, anti-freeze proteins (AFPs) are anchored on 1µm-polystyrene (PS) particles, and their behavior in the surface grooves on the ice is studied. The threshold temperature is an effective criterion for evaluating chemical interactions between particles and ice walls. The AFP binding on 1µm PS particles lowers the threshold temperature by 2.5°C, indicating interactions between AFPs on the PS particles and the ice wall. Because the AFPs studied here show selectivity towards the prism plane, it is critical that the prism plane of the ice crystal is in contact with the FCS in the surface grooves. Copyright © 2017 Elsevier B.V. All rights reserved.

A novel method for unsteady flow field segmentation based on stochastic similarity of direction

NASA Astrophysics Data System (ADS)

Omata, Noriyasu; Shirayama, Susumu

2018-04-01

Recent developments in fluid dynamics research have opened up the possibility for the detailed quantitative understanding of unsteady flow fields. However, the visualization techniques currently in use generally provide only qualitative insights. A method for dividing the flow field into physically relevant regions of interest can help researchers quantify unsteady fluid behaviors. Most methods at present compare the trajectories of virtual Lagrangian particles. The time-invariant features of an unsteady flow are also frequently of interest, but the Lagrangian specification only reveals time-variant features. To address these challenges, we propose a novel method for the time-invariant spatial segmentation of an unsteady flow field. This segmentation method does not require Lagrangian particle tracking but instead quantitatively compares the stochastic models of the direction of the flow at each observed point. The proposed method is validated with several clustering tests for 3D flows past a sphere. Results show that the proposed method reveals the time-invariant, physically relevant structures of an unsteady flow.

A Novel Approach to Visualizing Dark Matter Simulations.

PubMed

Kaehler, R; Hahn, O; Abel, T

2012-12-01

In the last decades cosmological N-body dark matter simulations have enabled ab initio studies of the formation of structure in the Universe. Gravity amplified small density fluctuations generated shortly after the Big Bang, leading to the formation of galaxies in the cosmic web. These calculations have led to a growing demand for methods to analyze time-dependent particle based simulations. Rendering methods for such N-body simulation data usually employ some kind of splatting approach via point based rendering primitives and approximate the spatial distributions of physical quantities using kernel interpolation techniques, common in SPH (Smoothed Particle Hydrodynamics)-codes. This paper proposes three GPU-assisted rendering approaches, based on a new, more accurate method to compute the physical densities of dark matter simulation data. It uses full phase-space information to generate a tetrahedral tessellation of the computational domain, with mesh vertices defined by the simulation's dark matter particle positions. Over time the mesh is deformed by gravitational forces, causing the tetrahedral cells to warp and overlap. The new methods are well suited to visualize the cosmic web. In particular they preserve caustics, regions of high density that emerge, when several streams of dark matter particles share the same location in space, indicating the formation of structures like sheets, filaments and halos. We demonstrate the superior image quality of the new approaches in a comparison with three standard rendering techniques for N-body simulation data.

Physics of Alfvén waves and energetic particles in burning plasmas

NASA Astrophysics Data System (ADS)

Chen, Liu; Zonca, Fulvio

2016-01-01

Dynamics of shear Alfvén waves and energetic particles are crucial to the performance of burning fusion plasmas. This article reviews linear as well as nonlinear physics of shear Alfvén waves and their self-consistent interaction with energetic particles in tokamak fusion devices. More specifically, the review on the linear physics deals with wave spectral properties and collective excitations by energetic particles via wave-particle resonances. The nonlinear physics deals with nonlinear wave-wave interactions as well as nonlinear wave-energetic particle interactions. Both linear as well as nonlinear physics demonstrate the qualitatively important roles played by realistic equilibrium nonuniformities, magnetic field geometries, and the specific radial mode structures in determining the instability evolution, saturation, and, ultimately, energetic-particle transport. These topics are presented within a single unified theoretical framework, where experimental observations and numerical simulation results are referred to elucidate concepts and physics processes.

The bead on a rotating hoop revisited: an unexpected resonance

NASA Astrophysics Data System (ADS)

Raviola, Lisandro A.; Véliz, Maximiliano E.; Salomone, Horacio D.; Olivieri, Néstor A.; Rodríguez, Eduardo E.

2017-01-01

The bead on a rotating hoop is a typical problem in mechanics, frequently posed to junior science and engineering students in basic physics courses. Although this system has a rich dynamics, it is usually not analysed beyond the point particle approximation in undergraduate textbooks, nor empirically investigated. Advanced textbooks show the existence of bifurcations owing to the system's nonlinear nature, and some papers demonstrate, from a theoretical standpoint, its points of contact with phase transition phenomena. However, scarce experimental research has been conducted to better understand its behaviour. We show in this paper that a minor modification to the problem leads to appealing consequences that can be studied both theoretically and empirically with the basic conceptual tools and experimental skills available to junior students. In particular, we go beyond the point particle approximation by treating the bead as a rigid spherical body, and explore the effect of a slightly non-vertical hoop's rotation axis that gives rise to a resonant behaviour not considered in previous works. This study can be accomplished by means of digital video and open source software. The experience can motivate an engaging laboratory project by integrating standard curriculum topics, data analysis and experimental exploration.

Global chaotization of fluid particle trajectories in a sheared two-layer two-vortex flow.

PubMed

Ryzhov, Evgeny A; Koshel, Konstantin V

2015-10-01

In a two-layer quasi-geostrophic approximation, we study the irregular dynamics of fluid particles arising due to two interacting point vortices embedded in a deformation flow consisting of shear and rotational components. The two vortices are arranged within the bottom layer, but an emphasis is on the upper-layer fluid particle motion. Vortices moving in one layer induce stirring of passive scalars in the other layer. This is of interest since point vortices induce singular velocity fields in the layer they belong to; however, in the other layer, they induce regular velocity fields that generally result in a change in passive particle stirring. If the vortices are located at stagnation points, there are three different types of the fluid flow. We examine how properties of each flow configuration are modified if the vortices are displaced from the stagnation points and thus circulate in the immediate vicinity of these points. To that end, an analysis of the steady-state configurations is presented with an emphasis on the frequencies of fluid particle oscillations about the elliptic stagnation points. Asymptotic relations for the vortex and fluid particle zero-oscillation frequencies are derived in the vicinity of the corresponding elliptic points. By comparing the frequencies of fluid particles with the ones of the vortices, relations between the parameters that lead to enhanced stirring of fluid particles are established. It is also demonstrated that, if the central critical point is elliptic, then the fluid particle trajectories in its immediate vicinity are mostly stable making it harder for the vortex perturbation to induce stirring. Change in the type of the central point to a hyperbolic one enhances drastically the size of the chaotic dynamics region. Conditions on the type of the central critical point also ensue from the derived asymptotic relations.

Physical Investigations of Small Particles: (I) Aerosol Particle Charging and Flux Enhancement and (II) Whispering Gallery Mode Sensing

NASA Astrophysics Data System (ADS)

Lopez-Yglesias, Xerxes

Part I: Particles are a key feature of planetary atmospheres. On Earth they represent the greatest source of uncertainty in the global energy budget. This uncertainty can be addressed by making more measurement, by improving the theoretical analysis of measurements, and by better modeling basic particle nucleation and initial particle growth within an atmosphere. This work will focus on the latter two methods of improvement. Uncertainty in measurements is largely due to particle charging. Accurate descriptions of particle charging are challenging because one deals with particles in a gas as opposed to a vacuum, so different length scales come into play. Previous studies have considered the effects of transition between the continuum and kinetic regime and the effects of two and three body interactions within the kinetic regime. These studies, however, use questionable assumptions about the charging process which resulted in skewed observations, and bias in the proposed dynamics of aerosol particles. These assumptions affect both the ions and particles in the system. Ions are assumed to be point monopoles that have a single characteristic speed rather than follow a distribution. Particles are assumed to be perfect conductors that have up to five elementary charges on them. The effects of three body interaction, ion-molecule-particle, are also overestimated. By revising this theory so that the basic physical attributes of both ions and particles and their interactions are better represented, we are able to make more accurate predictions of particle charging in both the kinetic and continuum regimes. The same revised theory that was used above to model ion charging can also be applied to the flux of neutral vapor phase molecules to a particle or initial cluster. Using these results we can model the vapor flux to a neutral or charged particle due to diffusion and electromagnetic interactions. In many classical theories currently applied to these models, the finite size of the molecule and the electromagnetic interaction between the molecule and particle, especially for the neutral particle case, are completely ignored, or, as is often the case for a permanent dipole vapor species, strongly underestimated. Comparing our model to these classical models we determine an "enhancement factor" to characterize how important the addition of these physical parameters and processes is to the understanding of particle nucleation and growth. Part II: Whispering gallery mode (WGM) optical biosensors are capable of extraordinarily sensitive specific and non-specific detection of species suspended in a gas or fluid. Recent experimental results suggest that these devices may attain single-molecule sensitivity to protein solutions in the form of stepwise shifts in their resonance wavelength, lambdaR, but present sensor models predict much smaller steps than were reported. This study examines the physical interaction between a WGM sensor and a molecule adsorbed to its surface, exploring assumptions made in previous efforts to model WGM sensor behavior, and describing computational schemes that model the experiments for which single protein sensitivity was reported. The resulting model is used to simulate sensor performance, within constraints imposed by the limited material property data. On this basis, we conclude that nonlinear optical effects would be needed to attain the reported sensitivity, and that, in the experiments for which extreme sensitivity was reported, a bound protein experiences optical energy fluxes too high for such effects to be ignored.

Fermilab | Science at Fermilab | Experiments & Projects | Energy Frontier

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Fermilab | Science at Fermilab | Experiments & Projects

Science.gov Websites

Go Science at Fermilab Fermilab and the Higgs Boson Frontiers of Particle Physics Experiments & Answers Submit a Question Frontiers of Particle Physics Benefits to Society Benefits to Society Medicine Inquiring Minds Questions About Physics Other High-Energy Physics Sites More About Particle Physics Library

Nuclear and Particle Physics, Astrophysics and Cosmology : T-2 : LANL

Science.gov Websites

linked in Search T-2, Nuclear and Particle Physics, Astrophysics and Cosmology T-2 Home T Division Focus Areas Nuclear Information Service Nuclear Physics Particle Physics Astrophysics Cosmology CONTACTS Group energy security, heavy ion physics, nuclear astrophysics, physics beyond the standard model, neutrino

FPGA Implementation of an Efficient Algorithm for the Calculation of Charged Particle Trajectories in Cosmic Ray Detectors

NASA Astrophysics Data System (ADS)

Villar, Xabier; Piso, Daniel; Bruguera, Javier D.

2014-02-01

This paper presents an FPGA implementation of an algorithm, previously published, for the the reconstruction of cosmic rays' trajectories and the determination of the time of arrival and velocity of the particles. The accuracy and precision issues of the algorithm have been analyzed to propose a suitable implementation. Thus, a 32-bit fixed-point format has been used for the representation of the data values. Moreover, the dependencies among the different operations have been taken into account to obtain a highly parallel and efficient hardware implementation. The final hardware architecture requires 18 cycles to process every particle, and has been exhaustively simulated to validate all the design decisions. The architecture has been mapped over different commercial FPGAs, with a frequency of operation ranging from 300 MHz to 1.3 GHz, depending on the FPGA being used. Consequently, the number of particle trajectories processed per second is between 16 million and 72 million. The high number of particle trajectories calculated per second shows that the proposed FPGA implementation might be used also in high rate environments such as those found in particle and nuclear physics experiments.

From the nonlinear Fokker-Planck equation to the Vlasov description and back: Confined interacting particles with drag

NASA Astrophysics Data System (ADS)

Plastino, A. R.; Curado, E. M. F.; Nobre, F. D.; Tsallis, C.

2018-02-01

Nonlinear Fokker-Planck equations endowed with power-law diffusion terms have proven to be valuable tools for the study of diverse complex systems in physics, biology, and other fields. The nonlinearity appearing in these evolution equations can be interpreted as providing an effective description of a system of particles interacting via short-range forces while performing overdamped motion under the effect of an external confining potential. This point of view has been recently applied to the study of thermodynamical features of interacting vortices in type II superconductors. In the present work we explore an embedding of the nonlinear Fokker-Planck equation within a Vlasov equation, thus incorporating inertial effects to the concomitant particle dynamics. Exact time-dependent solutions of the q -Gaussian form (with compact support) are obtained for the Vlasov equation in the case of quadratic confining potentials.

Particle Laden Turbulence in a Radiation Environment Using a Portable High Preformace Solver Based on the Legion Runtime System

NASA Astrophysics Data System (ADS)

Torres, Hilario; Iaccarino, Gianluca

2017-11-01

Soleil-X is a multi-physics solver being developed at Stanford University as a part of the Predictive Science Academic Alliance Program II. Our goal is to conduct high fidelity simulations of particle laden turbulent flows in a radiation environment for solar energy receiver applications as well as to demonstrate our readiness to effectively utilize next generation Exascale machines. The novel aspect of Soleil-X is that it is built upon the Legion runtime system to enable easy portability to different parallel distributed heterogeneous architectures while also being written entirely in high-level/high-productivity languages (Ebb and Regent). An overview of the Soleil-X software architecture will be given. Results from coupled fluid flow, Lagrangian point particle tracking, and thermal radiation simulations will be presented. Performance diagnostic tools and metrics corresponding the the same cases will also be discussed. US Department of Energy, National Nuclear Security Administration.

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2011-12-27

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb –1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particlesmore » in an R-parity-violating scenario as a function of the neutralino lifetime. Furthermore, limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.« less

Microworm optode sensors limit particle diffusion to enable in vivo measurements.

PubMed

Ozaydin-Ince, Gozde; Dubach, J Matthew; Gleason, Karen K; Clark, Heather A

2011-02-15

There have been a variety of nanoparticles created for in vivo uses ranging from gene and drug delivery to tumor imaging and physiological monitoring. The use of nanoparticles to measure physiological conditions while being fluorescently addressed through the skin provides an ideal method toward minimally invasive health monitoring. Here we create unique particles that have all the necessary physical characteristics to serve as in vivo reporters, but with minimized diffusion from the point of injection. These particles, called microworms, have a cylindrical shape coated with a biocompatible porous membrane that possesses a large surface-area-to-volume ratio while maintaining a large hydrodynamic radius. We use these microworms to create fluorescent sodium sensors for use as in vivo sodium concentration detectors after subcutaneous injection. However, the microworm concept has the potential to extend to the immobilization of other types of polymers for continuous physiological detection or delivery of molecules.

Framework for Understanding LENR Processes, Using Ordinary Condensed Matter Physics

NASA Astrophysics Data System (ADS)

Chubb, Scott

2005-03-01

As I have emphasizedootnotetextS.R. Chubb, Proc. ICCF10 (in press). Also, http://www.lenr-canr.org/acrobat/ChubbSRnutsandbol.pdf http://www.lenr-canr.org/acrobat/ChubbSRnutsandbol.pdf, S.R. Chubb, Trans. Amer. Nuc. Soc. 88 , 618 (2003)., in discussions of Low Energy Nuclear Reactions(LENRs), mainstream many-body physics ideas have been largely ignored. A key point is that in condensed matter, delocalized, wave-like effects can allow large amounts of momentum to be transferred instantly to distant locations, without any particular particle (or particles) acquiring high velocity through a Broken Gauge Symmetry. Explicit features in the electronic structure explain how this can occur^1 in finite size PdD crystals, with real boundaries. The essential physics^1 can be related to standard many-body techniquesootnotetextBurke,P.G. and K.A. Berrington, Atomic and Molecular Processes:an R matrix Approach (Bristol: IOP Publishing, 1993).. In the paper, I examine this relationship, the relationship of the theory^1 to other LENR theories, and the importance of certain features (for example, boundaries^1) that are not included in the other LENR theories.

Effect of binder liquid type on spherical crystallization.

PubMed

Maghsoodi, Maryam; Hajipour, Ali

2014-11-01

Spherical crystallization is a process of formation of agglomerates of crystals held together by binder liquid. This research focused on understanding the effect of type of solvents used as binder liquid on the agglomeration of crystals. Carbamazepine and ethanol/water were used respectively as a model drug and crystallization system. Eight solvents as binder liquid including chloroform, dichloromethane, isopropyl acetate, ethyl acetate, n-hexane, dimethyl aniline, benzene and toluene were examined to better understand the relationship between the physical properties of the binder liquid and its ability to bring about the formation of the agglomerates. Moreover, the agglomerates obtained from effective solvents as binder liquid were evaluated in term of size, apparent particle density and compressive strength. In this study the clear trend was observed experimentally in the agglomerate formation as a function of physical properties of the binder liquid such as miscibility with crystallization system. Furthermore, the properties of obtained agglomerates such as size, apparent particle density and compressive strength were directly related to physical properties of effective binder liquids. RESULTS of this study offer a useful starting point for a conceptual framework to guide the selection of solvent systems for spherical crystallization.

2D modeling of direct laser metal deposition process using a finite particle method

NASA Astrophysics Data System (ADS)

Anedaf, T.; Abbès, B.; Abbès, F.; Li, Y. M.

2018-05-01

Direct laser metal deposition is one of the material additive manufacturing processes used to produce complex metallic parts. A thorough understanding of the underlying physical phenomena is required to obtain a high-quality parts. In this work, a mathematical model is presented to simulate the coaxial laser direct deposition process tacking into account of mass addition, heat transfer, and fluid flow with free surface and melting. The fluid flow in the melt pool together with mass and energy balances are solved using the Computational Fluid Dynamics (CFD) software NOGRID-points, based on the meshless Finite Pointset Method (FPM). The basis of the computations is a point cloud, which represents the continuum fluid domain. Each finite point carries all fluid information (density, velocity, pressure and temperature). The dynamic shape of the molten zone is explicitly described by the point cloud. The proposed model is used to simulate a single layer cladding.

A source of antihydrogen for in-flight hyperfine spectroscopy

PubMed Central

Kuroda, N.; Ulmer, S.; Murtagh, D. J.; Van Gorp, S.; Nagata, Y.; Diermaier, M.; Federmann, S.; Leali, M.; Malbrunot, C.; Mascagna, V.; Massiczek, O.; Michishio, K.; Mizutani, T.; Mohri, A.; Nagahama, H.; Ohtsuka, M.; Radics, B.; Sakurai, S.; Sauerzopf, C.; Suzuki, K.; Tajima, M.; Torii, H. A.; Venturelli, L.; Wu¨nschek, B.; Zmeskal, J.; Zurlo, N.; Higaki, H.; Kanai, Y.; Lodi Rizzini, E.; Nagashima, Y.; Matsuda, Y.; Widmann, E.; Yamazaki, Y.

2014-01-01

Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy. PMID:24448273

Particle astrophysics

NASA Technical Reports Server (NTRS)

Sadoulet, Bernard; Cronin, James; Aprile, Elena; Barish, Barry C.; Beier, Eugene W.; Brandenberger, Robert; Cabrera, Blas; Caldwell, David; Cassiday, George; Cline, David B.

1991-01-01

The following scientific areas are reviewed: (1) cosmology and particle physics (particle physics and the early universe, dark matter, and other relics); (2) stellar physics and particles (solar neutrinos, supernovae, and unconventional particle physics); (3) high energy gamma ray and neutrino astronomy; (4) cosmic rays (space and ground observations). Highest scientific priorities for the next decade include implementation of the current program, new initiatives, and longer-term programs. Essential technological developments, such as cryogenic detectors of particles, new solar neutrino techniques, and new extensive air shower detectors, are discussed. Also a certain number of institutional issues (the funding of particle astrophysics, recommended funding mechanisms, recommended facilities, international collaborations, and education and technology) which will become critical in the coming decade are presented.

Feynman-diagrams approach to the quantum Rabi model for ultrastrong cavity QED: stimulated emission and reabsorption of virtual particles dressing a physical excitation

NASA Astrophysics Data System (ADS)

Di Stefano, Omar; Stassi, Roberto; Garziano, Luigi; Frisk Kockum, Anton; Savasta, Salvatore; Nori, Franco

2017-05-01

In quantum field theory, bare particles are dressed by a cloud of virtual particles to form physical particles. The virtual particles affect properties such as the mass and charge of the physical particles, and it is only these modified properties that can be measured in experiments, not the properties of the bare particles. The influence of virtual particles is prominent in the ultrastrong-coupling regime of cavity quantum electrodynamics (QED), which has recently been realised in several condensed-matter systems. In some of these systems, the effective interaction between atom-like transitions and the cavity photons can be switched on or off by external control pulses. This offers unprecedented possibilities for exploring quantum vacuum fluctuations and the relation between physical and bare particles. We consider a single three-level quantum system coupled to an optical resonator. Here we show that, by applying external electromagnetic pulses of suitable amplitude and frequency, each virtual photon dressing a physical excitation in cavity-QED systems can be converted into a physical observable photon, and back again. In this way, the hidden relationship between the bare and the physical excitations can be unravelled and becomes experimentally testable. The conversion between virtual and physical photons can be clearly pictured using Feynman diagrams with cut loops.

The radiation fields around a proton therapy facility: A comparison of Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Ottaviano, G.; Picardi, L.; Pillon, M.; Ronsivalle, C.; Sandri, S.

2014-02-01

A proton therapy test facility with a beam current lower than 10 nA in average, and an energy up to 150 MeV, is planned to be sited at the Frascati ENEA Research Center, in Italy. The accelerator is composed of a sequence of linear sections. The first one is a commercial 7 MeV proton linac, from which the beam is injected in a SCDTL (Side Coupled Drift Tube Linac) structure reaching the energy of 52 MeV. Then a conventional CCL (coupled Cavity Linac) with side coupling cavities completes the accelerator. The linear structure has the important advantage that the main radiation losses during the acceleration process occur to protons with energy below 20 MeV, with a consequent low production of neutrons and secondary radiation. From the radiation protection point of view the source of radiation for this facility is then almost completely located at the final target. Physical and geometrical models of the device have been developed and implemented into radiation transport computer codes based on the Monte Carlo method. The scope is the assessment of the radiation field around the main source for supporting the safety analysis. For the assessment independent researchers used two different Monte Carlo computer codes named FLUKA (FLUktuierende KAskade) and MCNPX (Monte Carlo N-Particle eXtended) respectively. Both are general purpose tools for calculations of particle transport and interactions with matter, covering an extended range of applications including proton beam analysis. Nevertheless each one utilizes its own nuclear cross section libraries and uses specific physics models for particle types and energies. The models implemented into the codes are described and the results are presented. The differences between the two calculations are reported and discussed pointing out disadvantages and advantages of each code in the specific application.

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

NASA Astrophysics Data System (ADS)

Purkayastha, Archak; Dubi, Yonatan

2017-08-01

Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments, and more. Here, we formulate a rigorous microscopic theory of an out-of-equilibrium open quantum system of noninteracting particles on a lattice weakly coupled bilinearly to multiple baths and driven by periodically varying thermodynamic parameters like temperature and chemical potential of the bath. The particles can be either bosonic or fermionic and the lattice can be of any dimension and geometry. Based on the Redfield quantum master equation under Born-Markov approximation, we derive a linear differential equation for an equal time two point correlation matrix, sometimes also called a single-particle density matrix, from which various physical observables, for example, current, can be calculated. Various interesting physical effects, such as resonance, can be directly read off from the equations. Thus, our theory is quite general and gives quite transparent and easy-to-calculate results. We validate our theory by comparing with exact numerical simulations. We apply our method to a generic open quantum system, namely, a double quantum dot coupled to leads with modulating chemical potentials. The two most important experimentally relevant insights from this are as follows: (i) Time-dependent measurements of current for symmetric oscillating voltages (with zero instantaneous voltage bias) can point to the degree of asymmetry in the system-bath coupling and (ii) under certain conditions time-dependent currents can exceed time-averaged currents by several orders of magnitude, and can therefore be detected even when the average current is below the measurement threshold.

Integral transforms of the quantum mechanical path integral: Hit function and path-averaged potential.

PubMed

Edwards, James P; Gerber, Urs; Schubert, Christian; Trejo, Maria Anabel; Weber, Axel

2018-04-01

We introduce two integral transforms of the quantum mechanical transition kernel that represent physical information about the path integral. These transforms can be interpreted as probability distributions on particle trajectories measuring respectively the relative contribution to the path integral from paths crossing a given spatial point (the hit function) and the likelihood of values of the line integral of the potential along a path in the ensemble (the path-averaged potential).

Integral transforms of the quantum mechanical path integral: Hit function and path-averaged potential

NASA Astrophysics Data System (ADS)

Edwards, James P.; Gerber, Urs; Schubert, Christian; Trejo, Maria Anabel; Weber, Axel

2018-04-01

We introduce two integral transforms of the quantum mechanical transition kernel that represent physical information about the path integral. These transforms can be interpreted as probability distributions on particle trajectories measuring respectively the relative contribution to the path integral from paths crossing a given spatial point (the hit function) and the likelihood of values of the line integral of the potential along a path in the ensemble (the path-averaged potential).

New class of two-loop neutrino mass models with distinguishable phenomenology

NASA Astrophysics Data System (ADS)

Cao, Qing-Hong; Chen, Shao-Long; Ma, Ernest; Yan, Bin; Zhang, Dong-Ming

2018-04-01

We discuss a new class of neutrino mass models generated in two loops, and explore specifically three new physics scenarios: (A) doubly charged scalar, (B) dark matter, and (C) leptoquark and diquark, which are verifiable at the 14 TeV LHC Run-II. We point out how the different Higgs insertions will distinguish our two-loop topology with others if the new particles in the loop are in the simplest representations of the SM gauge group.

An adhered-particle analysis system based on concave points

NASA Astrophysics Data System (ADS)

Wang, Wencheng; Guan, Fengnian; Feng, Lin

2018-04-01

Particles adhered together will influence the image analysis in computer vision system. In this paper, a method based on concave point is designed. First, corner detection algorithm is adopted to obtain a rough estimation of potential concave points after image segmentation. Then, it computes the area ratio of the candidates to accurately localize the final separation points. Finally, it uses the separation points of each particle and the neighboring pixels to estimate the original particles before adhesion and provides estimated profile images. The experimental results have shown that this approach can provide good results that match the human visual cognitive mechanism.

Identification of possible sources of particulate matter in the personal cloud using SEM/EDX

NASA Astrophysics Data System (ADS)

Conner, Teri L.; Williams, Ronald W.

2004-10-01

The United States Environmental Protection Agency (US EPA) conducted the Baltimore Particulate Matter (PM) Epidemiology-Exposure Study of the Elderly during the summer of 1998. The study design included PM2.5 samples obtained from elderly (65+ years of age) retirement facility residents using personal exposure sampling devices. These sampling devices were also used to obtain PM2.5 samples at fixed locations within the personal monitoring subjects' apartments. Selected personal and apartment samples were examined using scanning electron microscopy with individual-particle X-ray analysis (SEM/EDX), providing a qualitative assessment of the chemical and physical characteristics of geological and trace element particles collected within these micro-environments at the retirement facility. This information was used to identify possible indoor source particles. The manual surveys of the personal samples revealed that some particles larger than 2.5 μm reached the filter surface. Using SEM/EDX, several particle types with possible indoor origins were identified. The Al-Zr-Cl particle is likely to have originated from a personal antiperspirant product. Particles with a talc or alumino-silicate composition point to cosmetics as a possible source. Large cadmium-containing particles were also found, which may indicate the use of art pigments or ceramic glazes, or emissions from television screen phosphors. A greater variety of particles was observed in a personal sample compared with its corresponding fixed-location apartment sample.

Light-activated self-propelled colloids

PubMed Central

Palacci, J.; Sacanna, S.; Kim, S.-H.; Yi, G.-R.; Pine, D. J.; Chaikin, P. M.

2014-01-01

Light-activated self-propelled colloids are synthesized and their active motion is studied using optical microscopy. We propose a versatile route using different photoactive materials, and demonstrate a multiwavelength activation and propulsion. Thanks to the photoelectrochemical properties of two semiconductor materials (α-Fe2O3 and TiO2), a light with an energy higher than the bandgap triggers the reaction of decomposition of hydrogen peroxide and produces a chemical cloud around the particle. It induces a phoretic attraction with neighbouring colloids as well as an osmotic self-propulsion of the particle on the substrate. We use these mechanisms to form colloidal cargos as well as self-propelled particles where the light-activated component is embedded into a dielectric sphere. The particles are self-propelled along a direction otherwise randomized by thermal fluctuations, and exhibit a persistent random walk. For sufficient surface density, the particles spontaneously form ‘living crystals’ which are mobile, break apart and reform. Steering the particle with an external magnetic field, we show that the formation of the dense phase results from the collisions heads-on of the particles. This effect is intrinsically non-equilibrium and a novel principle of organization for systems without detailed balance. Engineering families of particles self-propelled by different wavelength demonstrate a good understanding of both the physics and the chemistry behind the system and points to a general route for designing new families of self-propelled particles. PMID:25332383

A novel quantum-mechanical interpretation of the Dirac equation

NASA Astrophysics Data System (ADS)

K-H Kiessling, M.; Tahvildar-Zadeh, A. S.

2016-04-01

A novel interpretation is given of Dirac’s ‘wave equation for the relativistic electron’ as a quantum-mechanical one-particle equation. In this interpretation the electron and the positron are merely the two different ‘topological spin’ states of a single more fundamental particle, not distinct particles in their own right. The new interpretation is backed up by the existence of such ‘bi-particle’ structures in general relativity, in particular the ring singularity present in any spacelike section of the spacetime singularity of the maximal-analytically extended, topologically non-trivial, electromagnetic Kerr-Newman (KN)spacetime in the zero-gravity limit (here, ‘zero-gravity’ means the limit G\\to 0, where G is Newton’s constant of universal gravitation). This novel interpretation resolves the dilemma that Dirac’s wave equation seems to be capable of describing both the electron and the positron in ‘external’ fields in many relevant situations, while the bi-spinorial wave function has only a single position variable in its argument, not two—as it should if it were a quantum-mechanical two-particle wave equation. A Dirac equation is formulated for such a ring-like bi-particle which interacts with a static point charge located elsewhere in the topologically non-trivial physical space associated with the moving ring particle, the motion being governed by a de Broglie-Bohm type law extracted from the Dirac equation. As an application, the pertinent general-relativistic zero-gravity hydrogen problem is studied in the usual Born-Oppenheimer approximation. Its spectral results suggest that the zero-G KN magnetic moment be identified with the so-called ‘anomalous magnetic moment of the physical electron,’ not with the Bohr magneton, so that the ring radius is only a tiny fraction of the electron’s reduced Compton wavelength.

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Surface charge features of kaolinite particles and their interactions

NASA Astrophysics Data System (ADS)

Gupta, Vishal

Kaolinite is both a blessing and a curse. As an important industrial mineral commodity, kaolinite clays are extensively used in the paper, ceramic, paint, plastic and rubber industries. In all these applications the wettability, aggregation, dispersion, flotation and thickening of kaolinite particles are affected by its crystal structure and surface properties. It is therefore the objective of this research to investigate selected physical and surface chemical properties of kaolinite, specifically the surface charge of kaolinite particles. A pool of advanced analytical techniques such as XRD, XRF, SEM, AFM, FTIR and ISS were utilized to investigate the morphological and surface chemistry features of kaolinite. Surface force measurements revealed that the silica tetrahedral face of kaolinite is negatively charged at pH>4, whereas the alumina octahedral face of kaolinite is positively charged at pH<6, and negatively charged at pH>8. Based on electrophoresis measurements, the apparent iso-electric point for kaolinite particles was determined to be less than pH 3. In contrast, the point of zero charge was determined to be pH 4.5 by titration techniques, which corresponds to the iso-electric point of between pH 4 and 5 as determined by surface force measurements. Results from kaolinite particle interactions indicate that the silica face--alumina face interaction is dominant for kaolinite particle aggregation at low and intermediate pH values, which explains the maximum shear yield stress at pH 5-5.5. Lattice resolution images reveal the hexagonal lattice structure of these two face surfaces of kaolinite. Analysis of the silica face of kaolinite showed that the center of the hexagonal ring of oxygen atoms is vacant, whereas the alumina face showed that the hexagonal surface lattice ring of hydroxyls surround another hydroxyl in the center of the ring. High resolution transmission electron microscopy investigation of kaolinite has indicated that kaolinite is indeed composed of silica/alumina bilayers with a c-spacing of 7.2 A. The surface charge densities of the silica face, the alumina face and the edge surface of kaolinite all influence particle interactions, and thereby affect the mechanical properties of kaolinite suspensions. The improved knowledge of kaolinite surface chemistry from this dissertation research provides a foundation for the development of improved process strategies for both the use and disposal of clay particles such as kaolinite.

Discontinuous gradient differential equations and trajectories in the calculus of variations

NASA Astrophysics Data System (ADS)

Bogaevskii, I. A.

2006-12-01

The concept of gradient of smooth functions is generalized for their sums with concave functions. An existence, uniqueness, and continuous dependence theorem for increasing time is formulated and proved for solutions of an ordinary differential equation the right-hand side of which is the gradient of the sum of a concave and a smooth function. With the use of this result a physically natural motion of particles, well defined even at discontinuities of the velocity field, is constructed in the variational problem of the minimal mechanical action in a space of arbitrary dimension. For such a motion of particles in the plane all typical cases of the birth and the interaction of point clusters of positive mass are described.

Applications of Nuclear and Particle Physics Technology: Particles & Detection — A Brief Overview

NASA Astrophysics Data System (ADS)

Weisenberger, Andrew G.

A brief overview of the technology applications with significant societal benefit that have their origins in nuclear and particle physics research is presented. It is shown through representative examples that applications of nuclear physics can be classified into two basic areas: 1) applying the results of experimental nuclear physics and 2) applying the tools of experimental nuclear physics. Examples of the application of the tools of experimental nuclear and particle physics research are provided in the fields of accelerator and detector based technologies namely synchrotron light sources, nuclear medicine, ion implantation and radiation therapy.

Analysing the health effects of simultaneous exposure to physical and chemical properties of airborne particles

PubMed Central

Pirani, Monica; Best, Nicky; Blangiardo, Marta; Liverani, Silvia; Atkinson, Richard W.; Fuller, Gary W.

2015-01-01

Background Airborne particles are a complex mix of organic and inorganic compounds, with a range of physical and chemical properties. Estimation of how simultaneous exposure to air particles affects the risk of adverse health response represents a challenge for scientific research and air quality management. In this paper, we present a Bayesian approach that can tackle this problem within the framework of time series analysis. Methods We used Dirichlet process mixture models to cluster time points with similar multipollutant and response profiles, while adjusting for seasonal cycles, trends and temporal components. Inference was carried out via Markov Chain Monte Carlo methods. We illustrated our approach using daily data of a range of particle metrics and respiratory mortality for London (UK) 2002–2005. To better quantify the average health impact of these particles, we measured the same set of metrics in 2012, and we computed and compared the posterior predictive distributions of mortality under the exposure scenario in 2012 vs 2005. Results The model resulted in a partition of the days into three clusters. We found a relative risk of 1.02 (95% credible intervals (CI): 1.00, 1.04) for respiratory mortality associated with days characterised by high posterior estimates of non-primary particles, especially nitrate and sulphate. We found a consistent reduction in the airborne particles in 2012 vs 2005 and the analysis of the posterior predictive distributions of respiratory mortality suggested an average annual decrease of − 3.5% (95% CI: − 0.12%, − 5.74%). Conclusions We proposed an effective approach that enabled the better understanding of hidden structures in multipollutant health effects within time series analysis. It allowed the identification of exposure metrics associated with respiratory mortality and provided a tool to assess the changes in health effects from various policies to control the ambient particle matter mixtures. PMID:25795926

Analysing the health effects of simultaneous exposure to physical and chemical properties of airborne particles.

PubMed

Pirani, Monica; Best, Nicky; Blangiardo, Marta; Liverani, Silvia; Atkinson, Richard W; Fuller, Gary W

2015-06-01

Airborne particles are a complex mix of organic and inorganic compounds, with a range of physical and chemical properties. Estimation of how simultaneous exposure to air particles affects the risk of adverse health response represents a challenge for scientific research and air quality management. In this paper, we present a Bayesian approach that can tackle this problem within the framework of time series analysis. We used Dirichlet process mixture models to cluster time points with similar multipollutant and response profiles, while adjusting for seasonal cycles, trends and temporal components. Inference was carried out via Markov Chain Monte Carlo methods. We illustrated our approach using daily data of a range of particle metrics and respiratory mortality for London (UK) 2002-2005. To better quantify the average health impact of these particles, we measured the same set of metrics in 2012, and we computed and compared the posterior predictive distributions of mortality under the exposure scenario in 2012 vs 2005. The model resulted in a partition of the days into three clusters. We found a relative risk of 1.02 (95% credible intervals (CI): 1.00, 1.04) for respiratory mortality associated with days characterised by high posterior estimates of non-primary particles, especially nitrate and sulphate. We found a consistent reduction in the airborne particles in 2012 vs 2005 and the analysis of the posterior predictive distributions of respiratory mortality suggested an average annual decrease of -3.5% (95% CI: -0.12%, -5.74%). We proposed an effective approach that enabled the better understanding of hidden structures in multipollutant health effects within time series analysis. It allowed the identification of exposure metrics associated with respiratory mortality and provided a tool to assess the changes in health effects from various policies to control the ambient particle matter mixtures. Copyright © 2015. Published by Elsevier Ltd.

Particle Accelerators Test Cosmological Theory.

ERIC Educational Resources Information Center

Schramm, David N.; Steigman, Gary

1988-01-01

Discusses the symbiotic relationship of cosmology and elementary-particle physics. Presents a brief overview of particle physics. Explains how cosmological considerations set limits on the number of types of elementary particles. (RT)

An Evaluation of the Particle Physics Masterclass as a Context for Student Learning about the Nature of Science

ERIC Educational Resources Information Center

Wadness, Michael J.

2010-01-01

This dissertation addresses the research question: To what extent do secondary school science students attending the U.S. Particle Physics Masterclass change their view of the nature of science (NOS)? The U.S. Particle Physics Masterclass is a physics outreach program run by QuarkNet, a national organization of secondary school physics teachers…

ForwArd Search ExpeRiment at the LHC

NASA Astrophysics Data System (ADS)

Feng, Jonathan L.; Galon, Iftah; Kling, Felix; Trojanowski, Sebastian

2018-02-01

New physics has traditionally been expected in the high-pT region at high-energy collider experiments. If new particles are light and weakly coupled, however, this focus may be completely misguided: light particles are typically highly concentrated within a few mrad of the beam line, allowing sensitive searches with small detectors, and even extremely weakly coupled particles may be produced in large numbers there. We propose a new experiment, forward search experiment, or FASER, which would be placed downstream of the ATLAS or CMS interaction point (IP) in the very forward region and operated concurrently there. Two representative on-axis locations are studied: a far location, 400 m from the IP and just off the beam tunnel, and a near location, just 150 m from the IP and right behind the TAN neutral particle absorber. For each location, we examine leading neutrino- and beam-induced backgrounds. As a concrete example of light, weakly coupled particles, we consider dark photons produced through light meson decay and proton bremsstrahlung. We find that even a relatively small and inexpensive cylindrical detector, with a radius of ˜10 cm and length of 5-10 m, depending on the location, can discover dark photons in a large and unprobed region of parameter space with dark photon mass mA'˜10 - 500 MeV and kinetic mixing parameter ɛ ˜10-6-10-3. FASER will clearly also be sensitive to many other forms of new physics. We conclude with a discussion of topics for further study that will be essential for understanding FASER's feasibility, optimizing its design, and realizing its discovery potential.

Transport of Zinc Oxide Nanoparticles in a Simulated Gastric Environment

NASA Astrophysics Data System (ADS)

Mayfield, Ryan T.

Recent years have seen a growing interest in the use of many types of nano sized materials in the consumer sector. Potential uses include encapsulation of nutrients, providing antimicrobial activity, altering texture, or changing bioavailability of nutrients. Engineered nanoparticles (ENP) possess properties that are different than larger particles made of the same constituents. Properties such as solubility, aggregation state, and toxicity can all be changed as a function of size. The gastric environment is an important area for study of engineered nanoparticles because of the varied physical, chemical, and enzymatic processes that are prevalent there. These all have the potential to alter those properties of ENP that make them different from their bulk counterparts. The Human Gastric Simulator (HGS) is an advanced in vitro model that can be used to study many facets of digestion. The HGS consists of a plastic lining that acts as the stomach cavity with two sets of U-shaped arms on belts that provide the physical forces needed to replicate peristalsis. Altering the position of the arms or changing the speed of the motor which powers them allows one to tightly hone and replicate varied digestive conditions. Gastric juice, consisting of salts, enzymes, and acid levels which replicate physiological conditions, is introduced to the cavity at a controllable rate. The release of digested food from the lumen of simulated stomach is controlled by a peristaltic pump. The goal of the HGS is to accurately and repeatedly simulate human digestion. This study focused on introducing foods spiked with zinc oxide ENP and bulk zinc oxide into the HGS and then monitoring how the concentration of each changed at two locations in the HGS over a two hour period. The two locations chosen were the highest point in the lumen of the stomach, which represented the fundus, and a point just beyond the equivalent of the pylorus, which represented the antrum of the stomach. These points were chosen in order to elucidate if and how two different particle sizes of the same material are transported during digestion. Results showed that particles preferentially collected at Location A; time played a minor role in the separation to the two locations while particle size did not play any role.

The influence of human physical activity and contaminated clothing type on particle resuspension.

PubMed

McDonagh, A; Byrne, M A

2014-01-01

A study was conducted to experimentally quantify the influence of three variables on the level of resuspension of hazardous aerosol particles from clothing. Variables investigated include physical activity level (two levels, low and high), surface type (four different clothing material types), and time i.e. the rate at which particles resuspend. A mixture of three monodisperse tracer-labelled powders, with median diameters of 3, 5, and 10 microns, was used to "contaminate" the samples, and the resuspended particles were analysed in real-time using an Aerodynamic Particle Sizer (APS), and also by Neutron Activation Analysis (NAA). The overall finding was that physical activity resulted in up to 67% of the contamination deposited on clothing being resuspended back into the air. A detailed examination of the influence of physical activity level on resuspension, from NAA, revealed that the average resuspended fraction (RF) of particles at low physical activity was 28 ± 8%, and at high physical activity was 30 ± 7%, while the APS data revealed a tenfold increase in the cumulative mass of airborne particles during high physical activity in comparison to that during low physical activity. The results also suggest that it is not the contaminated clothing's fibre type which influences particle resuspension, but the material's weave pattern (and hence the material's surface texture). Investigation of the time variation in resuspended particle concentrations indicated that the data were separable into two distinct regimes: the first (occurring within the first 1.5 min) having a high, positive rate of change of airborne particle concentration relative to the second regime. The second regime revealed a slower rate of change of particle concentration and remained relatively unchanged for the remainder of each resuspension event. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Origin of Inertia and Matter as a Superradiant Phase Transition of Quantum Vacuum

NASA Astrophysics Data System (ADS)

Maxmilian Caligiuri, Luigi

Mass is one of the most important concepts in physics and its real understanding represents the key for the formulation of any consistent physical theory. During the past years, a very interesting model of inertial and gravitational mass as the result of the reaction interaction between the charged particles (electrons and quarks) contained in a given body and a suitable "fraction" of QED Zero Point Fields confined within an ideal resonant cavity, associated to the same body, has been proposed by Haish, Rueda and Puthoff. More recently, the author showed that this interpretation is consistent with a picture of mass (both inertial and gravitational) as the seat of ZPF standing waves whose presence reduces quantum vacuum energy density inside the resonant cavity ideally associated to the body volume. Nevertheless so far, the ultimate physical origin of such resonant cavity as well as the mechanism able to "select" the fraction of ZPF electromagnetic modes interacting within it, remained unrevealed. In this paper, basing on the framework of QED coherence in condensed matter, we'll show mass can be viewed as the result of a spontaneous superradiant phase transition of quantum vacuum giving rise to a more stable, energetically favored, oscopic quantum state characterized by an ensemble of coherence domains, "trapping" the coherent ZPF fluctuations inside a given volume just acting as a resonant cavity. Our model is then able to explain the "natural" emergence of the ideal resonant cavity speculated by Haish, Rueda and Puthoff and its defining parameters as well as the physical mechanism selecting the fraction of ZPF interacting with the body particles. Finally, a generalization of the model to explain the origin of mass of elementary particles is proposed also suggesting a new understanding of Compton's frequency and De Broglie's wavelength. Our results indicates both inertia and matter could truly originate from coherent interaction between quantum matter-wave and radiation fields condensed from quantum vacuum and also give novel and interesting insights into fundamental physical questions as, for example, the structure of elementary particles and matter stability.

Benefits of applying low-temperature plasma treatment to wound care and hemostasis from the viewpoints of physics and pathology

NASA Astrophysics Data System (ADS)

Shimizu, Tetsuji; Ikehara, Yuzuru

2017-12-01

Over the last decade, low-temperature plasma (LTP) technology has reached the life sciences and introduced the benefits of using such technology at atmospheric pressure for medical applications. The active elements from LTP, such as reactive molecular species, charged particles and photons, appear to react with biomolecules on wounds and at bleeding points. This action by LTP might be analogous with semiconductor fabrication techniques such as etching and surface modification. From this perspective, we discuss the general aspects and principles of LTP devices used at atmospheric pressure in wound care and hemostasis as an interdisciplinary fusion of applied physics and pathology.

(U) Physics Validation of the RMI-Based Ejecta Source Model Implementation in FLAG: L2 Milestone #6035 Report

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

Tregillis, I. L.

The Los Alamos Physics and Engineering Models (PEM) program has developed a model for Richtmyer-Meshkov instability (RMI) based ejecta production from shock-melted surfaces, along with a prescription for a self-similar velocity distribution (SSVD) of the resulting ejecta particles. We have undertaken an effort to validate this source model using data from explosively driven tin coupon experiments. The model’s current formulation lacks a crucial piece of physics: a method for determining the duration of the ejecta production interval. Without a mechanism for terminating ejecta production, the model is not predictive. Furthermore, when the production interval is hand-tuned to match time-integrated massmore » data, the predicted time-dependent mass accumulation on a downstream sensor rises too sharply at early times and too slowly at late times because the SSVD overestimates the amount of mass stored in the fastest particles and underestimates the mass stored in the slowest particles. The functional form of the resulting m(t) is inconsistent with the available time-dependent data; numerical simulations and analytic studies agree on this point. Simulated mass tallies are highly sensitive to radial expansion of the ejecta cloud. It is not clear if the same effect is present in the experimental data but if so, depending on the degree, this may challenge the model’s compatibility with tin coupon data. The current implementation of the model in FLAG is sensitive to the detailed interaction between kinematics (hydrodynamic methods) and thermodynamics (material models); this sensitivity prohibits certain physics modeling choices. The appendices contain an extensive analytic study of piezoelectric ejecta mass measurements, along with test problems, excerpted from a longer work (LA-UR-17-21218).« less

Modeling the solute transport by particle-tracing method with variable weights

NASA Astrophysics Data System (ADS)

Jiang, J.

2016-12-01

Particle-tracing method is usually used to simulate the solute transport in fracture media. In this method, the concentration at one point is proportional to number of particles visiting this point. However, this method is rather inefficient at the points with small concentration. Few particles visit these points, which leads to violent oscillation or gives zero value of concentration. In this paper, we proposed a particle-tracing method with variable weights. The concentration at one point is proportional to the sum of the weights of the particles visiting it. It adjusts the weight factors during simulations according to the estimated probabilities of corresponding walks. If the weight W of a tracking particle is larger than the relative concentration C at the corresponding site, the tracking particle will be splitted into Int(W/C) copies and each copy will be simulated independently with the weight W/Int(W/C) . If the weight W of a tracking particle is less than the relative concentration C at the corresponding site, the tracking particle will be continually tracked with a probability W/C and the weight will be adjusted to be C. By adjusting weights, the number of visiting particles distributes evenly in the whole range. Through this variable weights scheme, we can eliminate the violent oscillation and increase the accuracy of orders of magnitudes.

Phase diagrams and Hofstadter butterflies in the strongly correlated bosonic systems on the lattices with Dirac points

NASA Astrophysics Data System (ADS)

Sajna, A. S.; Polak, T. P.

2018-06-01

Gauge potentials with different configurations have been recently realized in the optical lattice experiments. It is remarkable that one of the simplest gauge potential can generate particle energy spectrum with the self-similar structure known as a Hofstadter butterfly. We investigate theoretically the impact of strong on-site interaction on such a spectrum in the bosonic Mott insulator within Bose-Hubbard model. In particular, it is shown that the fractal structure is encoded in the quasi-particle and hole bosonic branches for different lattice backgrounds. For example a square lattice and other structures (brick-wall and staggered magnetic flux lattice) which contain Dirac points in energy dispersions are considered. This shows that single-particle physics is still present even in the strong interaction limit for whole Hofstadter spectrum. Additionally we observe, that although in brick-wall and staggered flux lattices the quasi-particle densities of states look qualitatively similar, the corresponding Hofstadter butterfly assumes different forms. In particular, we use a superposition of two different synthetic gauge fields which appears to be a generator of non-trivial phenomena in the optical lattice systems. We also discuss the consequences of these phenomena on the phase diagrams between bosonic Mott insulator and superfluid phase. The analysis is carried out within the strong coupling expansion method on the finite size lattices and also at finite temperatures which are relevant for the currently made experiments.

Novel Optical Technique Developed and Tested for Measuring Two-Point Velocity Correlations in Turbulent Flows

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A.; Goldburg, Walter I.

2002-01-01

A novel technique for characterizing turbulent flows was developed and tested at the NASA Glenn Research Center. The work is being done in collaboration with the University of Pittsburgh, through a grant from the NASA Microgravity Fluid Physics Program. The technique we are using, Homodyne Correlation Spectroscopy (HCS), is a laser-light-scattering technique that measures the Doppler frequency shift of light scattered from microscopic particles in the fluid flow. Whereas Laser Doppler Velocimetry gives a local (single-point) measurement of the fluid velocity, the HCS technique measures correlations between fluid velocities at two separate points in the flow at the same instant of time. Velocity correlations in the flow field are of fundamental interest to turbulence researchers and are of practical importance in many engineering applications, such as aeronautics.

A multicore compound glass optical fiber for neutron imaging

NASA Astrophysics Data System (ADS)

Moore, Michael; Zhang, Xiaodong; Feng, Xian; Brambilla, Gilberto; Hayward, Jason

2017-04-01

Optical fibers have been successfully utilized for point sensors targeting physical quantities (stress, strain, rotation, acceleration), chemical compounds (humidity, oil, nitrates, alcohols, DNA) or radiation fields (X-rays, β particles, γ-rays). Similarly, bundles of fibers have been extremely successful in imaging visible wavelengths for medical endoscopy and industrial boroscopy. This work presents the progress in the fabrication and experimental evaluation of multicore fiber as neutron scattering instrumentation designed to detect and image neutrons with micron level spatial resolution.

Gauge/Gravity Duality

ScienceCinema

Polchinski, Joseph

2017-12-22

Gauge theories, which describe the particle interactions, are well understood, while quantum gravity leads to many puzzles. Remarkably, in recent years we have learned that these are actually dual, the same system written in different variables. On the one hand, this provides our most precise description of quantum gravity, resolves some long-standing paradoxes, and points to new principles. On the other, it gives a new perspective on strong interactions, with surprising connections to other areas of physics. I describe these ideas, and discuss current and future directions.

Monte Carlo study of exact {ital S}-matrix duality in nonsimply laced affine Toda theories

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

Beccaria, M.

The ({ital g}{sub 2}{sup (1)},{ital d}{sub 4}{sup (3)}) pair of nonsimply laced affine Toda theories is studied from the point of view of nonperturbative duality. The classical spectrum of each member is composed of two massive scalar particles. The exact {ital S}-matrix prediction for the dual behavior of the coupling-dependent mass ratio is found to be in strong agreement with Monte Carlo data. {copyright} {ital 1996 The American Physical Society.}

What's Next for Particle Physics?

NASA Astrophysics Data System (ADS)

White, Martin

2017-10-01

Following the discovery of the Higgs boson in 2012, particle physics has entered its most exciting and crucial period for over 50 years. In this book, I first summarise our current understanding of particle physics, and why this knowledge is almost certainly incomplete. We will then see that the Large Hadron Collider provides the means to search for the next theory of particle physics by performing precise measurements of the Higgs boson, and by looking directly for particles that can solve current cosmic mysteries such as the nature of dark matter. Finally, I will anticipate the next decade of particle physics by placing the Large Hadron Collider within the wider context of other experiments. The results expected over the next ten years promise to transform our understanding of what the Universe is made of and how it came to be.

Triply degenerate nodal points and topological phase transitions in NaCu3Te2

NASA Astrophysics Data System (ADS)

Xia, Yunyouyou; Li, Gang

2017-12-01

Quasiparticle excitations of free electrons in condensed-matter physics, characterized by the dimensionality of the band crossing, can find their elementary-particle analogs in high-energy physics, such as Majorana, Weyl, and Dirac fermions, while crystalline symmetry allows more quasiparticle excitations and exotic fermions to emerge. Using symmetry analysis and ab initio calculations, we propose that the three-dimensional honeycomb crystal NaCu3Te2 hosts triply degenerate nodal points (TDNPs) residing at the Fermi level. Furthermore, in this system we find a tunable phase transition between a trivial insulator, a TDNP phase, and a weak topological insulator (TI), triggered by a symmetry-allowed perturbation and the spin-orbital coupling (SOC). Such a topological nontrivial ternary compound not only serves as a perfect candidate for studying three-component fermions, but also provides an excellent playground for understanding the topological phase transitions between TDNPs, TIs, and trivial insulators, which distinguishes this system from other TDNP candidates.

The Web-based Module of Changes in Objects

NASA Astrophysics Data System (ADS)

Triayomi, R.

2017-09-01

To understand the changes of substances contained in such a kind of substance and substance characteristics then need a deep study of the concept. In this concept is expected to understand the changes of objects such as substance type and substance characteristics. Types of substances and characteristics of substances through physical changes and chemical changes and means of separation consisting of two or more substances. The principle of separation of the mixture is based on differences in physical properties of its constituents, such as substances, particle size, melting point, boiling point, magnetic properties, solubility, and so forth. This study aims to produce a web-based module of changes in objects that are valid, practical, and have effectiveness of student learning outcomes and activities on natural science learning. The experiment was conducted on 30 children in South Sumatera. The case of the development of the learning module of change of the object is influenced by the child’s understanding of the concept. Expected to be adapted by world teachers.

Statistical mechanics and combinatorics of some discrete lattice models

NASA Astrophysics Data System (ADS)

Ayyer, Arvind

Many problems in statistical physics involve enumeration of certain objects. In this thesis, we apply ideas from combinatorics and statistical physics to understand three different lattice models. (I) We investigate the structure of the nonequilibrium stationary state (NESS) of a system of first and second class particles on L sites of a one-dimensional lattice in contact with first class particle reservoirs at the boundary sites and second class particles constrained to lie the system. The internal dynamics are described by the usual totally asymmetric exclusion process (TASEP) with second class particles. We show in a conceptually simple way how pinned and unpinned (fat) shocks determine the general structure of the phase diagram. We also point out some unexpected features in the microscopic structure of the NESS both for finite L and in the limit L → infinity. In the latter case the local distribution of second class particles is given by an equilibrium pressure ensemble with a pair potential between neighboring particles which grows logarithmically with distance. (II) We model a long linear polymer constrained between two plates as a walk on a two-dimensional lattice constrained to lie between two lines, x = y and x = y+w, which interacts with these lines via contact parameters s and t. The atomic steps of the walk can be taken to be from an arbitrary but fixed set S with the only condition being that the first coordinate of every element in S is strictly positive. For any such S and any w, we prescribe general algorithms (fully implemented in Maple) for the automated calculation of several mathematical and physical quantities of interest. (III) Ferrers (or Young) diagrams are very classical objects in representation theory, whose half-perimeter generating function of Ferrers diagrams is a straightforward rational function. We construct two new classes of Ferrers diagrams, which we call wicketed and gated Ferrers diagrams, which have internal voids in the shape of Ferrers diagrams, and calculate their half-perimeter generating functions, one of which is closely related to the generating function of the Catalan numbers, using a more abstract version of the usual transfer matrix method.

Colloquium: Physics of the Riemann hypothesis

NASA Astrophysics Data System (ADS)

Schumayer, Dániel; Hutchinson, David A. W.

2011-04-01

Physicists become acquainted with special functions early in their studies. Consider our perennial model, the harmonic oscillator, for which we need Hermite functions, or the Laguerre functions in quantum mechanics. Here a particular number-theoretical function is chosen, the Riemann zeta function, and its influence on the realm of physics is examined and also how physics may be suggestive for the resolution of one of mathematics’ most famous unconfirmed conjectures, the Riemann hypothesis. Does physics hold an essential key to the solution for this more than 100-year-old problem? In this work numerous models from different branches of physics are examined, from classical mechanics to statistical physics, where this function plays an integral role. This function is also shown to be related to quantum chaos and how its pole structure encodes when particles can undergo Bose-Einstein condensation at low temperature. Throughout these examinations light is shed on how the Riemann hypothesis can highlight physics. Naturally, the aim is not to be comprehensive, but rather focusing on the major models and aim to give an informed starting point for the interested reader.

Particle Physics: From School to University.

ERIC Educational Resources Information Center

Barlow, Roger

1992-01-01

Discusses the teaching of particle physics as part of the A-level physics course in British secondary schools. Utilizes the quark model of hadrons and the conceptual kinematics of particle collisions, as examples, to demonstrate practical instructional possibilities in relation to student expectations. (JJK)

Nonequilibrium mode-coupling theory for dense active systems of self-propelled particles.

PubMed

Nandi, Saroj Kumar; Gov, Nir S

2017-10-25

The physics of active systems of self-propelled particles, in the regime of a dense liquid state, is an open puzzle of great current interest, both for statistical physics and because such systems appear in many biological contexts. We develop a nonequilibrium mode-coupling theory (MCT) for such systems, where activity is included as a colored noise with the particles having a self-propulsion force f 0 and a persistence time τ p . Using the extended MCT and a generalized fluctuation-dissipation theorem, we calculate the effective temperature T eff of the active fluid. The nonequilibrium nature of the systems is manifested through a time-dependent T eff that approaches a constant in the long-time limit, which depends on the activity parameters f 0 and τ p . We find, phenomenologically, that this long-time limit is captured by the potential energy of a single, trapped active particle (STAP). Through a scaling analysis close to the MCT glass transition point, we show that τ α , the α-relaxation time, behaves as τ α ∼ f 0 -2γ , where γ = 1.74 is the MCT exponent for the passive system. τ α may increase or decrease as a function of τ p depending on the type of active force correlations, but the behavior is always governed by the same value of the exponent γ. Comparison with the numerical solution of the nonequilibrium MCT and simulation results give excellent agreement with scaling analysis.

From Particle Physics to Medical Applications

NASA Astrophysics Data System (ADS)

Dosanjh, Manjit

2017-06-01

CERN is the world's largest particle physics research laboratory. Since it was established in 1954, it has made an outstanding contribution to our understanding of the fundamental particles and their interactions, and also to the technologies needed to analyse their properties and behaviour. The experimental challenges have pushed the performance of particle accelerators and detectors to the limits of our technical capabilities, and these groundbreaking technologies can also have a significant impact in applications beyond particle physics. In particular, the detectors developed for particle physics have led to improved techniques for medical imaging, while accelerator technologies lie at the heart of the irradiation methods that are widely used for treating cancer. Indeed, many important diagnostic and therapeutic techniques used by healthcare professionals are based either on basic physics principles or the technologies developed to carry out physics research. Ever since the discovery of x-rays by Roentgen in 1895, physics has been instrumental in the development of technologies in the biomedical domain, including the use of ionizing radiation for medical imaging and therapy. Some key examples that are explored in detail in this book include scanners based on positron emission tomography, as well as radiation therapy for cancer treatment. Even the collaborative model of particle physics is proving to be effective in catalysing multidisciplinary research for medical applications, ensuring that pioneering physics research is exploited for the benefit of all.

Let’s have a coffee with the Standard Model of particle physics!

NASA Astrophysics Data System (ADS)

Woithe, Julia; Wiener, Gerfried J.; Van der Veken, Frederik F.

2017-05-01

The Standard Model of particle physics is one of the most successful theories in physics and describes the fundamental interactions between elementary particles. It is encoded in a compact description, the so-called ‘Lagrangian’, which even fits on t-shirts and coffee mugs. This mathematical formulation, however, is complex and only rarely makes it into the physics classroom. Therefore, to support high school teachers in their challenging endeavour of introducing particle physics in the classroom, we provide a qualitative explanation of the terms of the Lagrangian and discuss their interpretation based on associated Feynman diagrams.

Soil mechanics on the Moon, Mars, and Mulberry

NASA Technical Reports Server (NTRS)

Carrier, W. D., III

1988-01-01

From a soil mechanics point of view, the Moon is a relatively simple place. Without any water, organics, or clay minerals, the geotechnical properties of the lunar soil are confined to a fairly limited range. Furthermore, the major soil-forming agent is meteorite impact, which breaks the big particles into little particles; and simultaneously, cements the little particles back together again with molten glass. After about a hundred million years of exposure to meteorite impact, the distribution of particle sizes in the soil achieves a sort of steady state. The majority of the returned lunar soil samples have been found to be well-graded silty-sand to sandy-silt (SM in the Unified Soil Classification System). Each of the particle size distributions plots within a relatively narrow band, which appears to be uniform over the entire lunar surface. This further restricts the range of physical properties of the lunar surface. In contrast, Martian soils should exhibit an extremely wide range of properties. We already know that there is a small amount of water in the soil, greater than in the Martian atmosphere. Furthermore, the soil is suspected to be smectitic clay. That makes two out of the three factors that greatly affect the properties of terrestrial soils.

The Poynting-Robertson effect: A critical perspective

NASA Astrophysics Data System (ADS)

Klačka, J.; Petržala, J.; Pástor, P.; Kómar, L.

2014-04-01

Physics of the Poynting-Robertson (P-R) effect is discussed and compared with the statements published in the past 30 years. Relativistically covariant formulation reveals the essence of the P-R effect and points out to nonphysical explanations in scientific papers and monographs. Although the final equation of motion m dv→/dt=(SA‧Q‾pr‧/c)[(1-v→·e→/c)e→-v→/c] has been usually correctly presented and used, its derivation and explanation of its essence is frequently incorrect. The difference between the effects of solar electromagnetic and corpuscular (solar wind) radiation is stressed. The force acting on the particle due to the solar wind (the simple case of radial solar wind velocity is considered) is F→sw=Fsw[(1-v→·e→/vsw)e→-x‧v→/vsw], where Fsw is the force on the stationary particle, vsw is the heliocentric solar-wind speed, and, the value of x‧ depends on material properties of the particle (1 < x‧ < 3). We present secular orbital evolution of dust particle under the action of the P-R effect. Initial conditions are included. Time of spiralling of the particle into the Sun is analytically calculated. Secular evolutions of perihelion and aphelion distances are investigated.

LECTURES ON PHYSICS, BIOPHYSICS, AND CHEMISTRY FOR HIGH SCHOOL SCIENCE TEACHERS GIVEN AT THE ERNEST O. LAWRENCE RADIATION LABORATORY, BERKELEY, CALIFORNIA, JUNE-AUGUST 1959

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

Calhoon, E.C.; Starring, P.W. eds.

1959-08-01

Lectures given at the Ernest 0. Lawrence Radiation Laboratory on physics, biophysics, and chemistry for high school science teachers are presented. Topics covered include a mathematics review, atomic physics, nuclear physics, solid-state physics, elementary particles, antiparticies, design of experiments, high-energy particle accelerators, survey of particle detectors, emulsion as a particle detector, counters used in high-energy physics, bubble chambers, computer programming, chromatography, the transuranium elements, health physics, photosynthesis, the chemistry and physics of virus, the biology of virus, lipoproteins and heart disease, origin and evolution of the solar system, the role of space satellites in gathering astronomical data, and radiation andmore » life in space. (M.C.G.)« less

Rheological and physical properties of spray-dried mucilage obtained from Hylocereus undatus cladodes.

PubMed

García-Cruz, E E; Rodríguez-Ramírez, J; Méndez Lagunas, L L; Medina-Torres, L

2013-01-02

This study examines the rheological behavior of reconstituted spray-dried mucilage isolated from the cladodes of pitahaya (Hylocereus undatus), the effects of concentration and its relationship with physical properties were analyzed in reconstituted solutions. Drying process optimization was carried out through the surface response method, utilizing a factorial 2(3) design with three central points, in order to evaluate yield and rheological properties. The reconstituted mucilage exhibited non-Newtonian shear-thinning behavior, which adequately fit the Cross model (R(2)>0.95). This dynamic response suggests a random coil configuration. The steady-shear viscosity and dynamic response are suitably correlated through the Cox-Merz rule, confirming the mucilage's stability of flow. Analysis of the physical properties of the mucilage (Tg, DTP, and particle morphology) explains the shear-thinning behavior. Copyright © 2012 Elsevier Ltd. All rights reserved.

Perspectives on individual to ensembles of ambient fine and ultrafine particles and their sources

NASA Astrophysics Data System (ADS)

Bein, Keith James

By combining Rapid Single-ultrafine-particle Mass Spectrometry (RSMS) measurements during the Pittsburgh Supersite experiment with a large array of concurrent PM, gas and meteorological data, a synthesis of data and analyses is employed to characterize sources, emission trends and dynamics of ambient fine and ultrafine particles. Combinatorial analyses elicit individual to ensemble descriptions of particles, their sources, their changes in state from atmospheric processing and the scales of motion driving their transport and dynamics. Major results include (1) Particle size and composition are strong indicators of sources/source categories and real-time measurements allow source attribution at the single particle and point source level. (2) Single particle source attribution compares well to factor analysis of chemically-speciated bulk phase data and both resulted in similar conclusions but independently revealed new sources. (3) RSMS data can quantitatively estimate composition-resolved, number-based particle size distribution. Comparison to mass-based data yielded new information about physical and chemical properties of particles and instrument sensitivity. (4) Source-specific signatures and real-time monitoring allow passing plumes to be tracked and characterized. (5) The largest of three identified coal combustion sources emits ˜ 2.4 x 10 17 primary submicron particles per second. (6) Long-range transport has a significant impact on the eastern U.S. including specific influences of eight separate wildfire events. (7) Pollutant dynamics in the Pittsburgh summertime air shed, and Northeastern U.S., is characterized by alternating periods of stagnation and cleansing. The eight wildfire events were detected in between seven successive stagnation events. (8) Connections exist between boreal fire activity, southeast subsiding transport of the emissions, alternating periods of stagnation and cleansing at the receptor and the structure and propagation of extratropical waves. (9) Wildfire emissions can severely impact preexisting pollutant concentrations and physical and chemical processes at the receptor. (10) High-severity crown fires in boreal Canada emit ˜ 1.2 x 1015 particles/kg biomass burned. (11) In 1998, wildfire activity in the circumpolar boreal forest emitted ˜ 8 x 1026 particles, representing ˜ 14% of global wildland fire emissions. Results and conclusions address future scientific objectives in understanding effects of particles on human health and global climate change.

Concentration of Micro and Nanoparticles in Sessile Droplets Using Asymmetric Surface Wave Irradiation

NASA Astrophysics Data System (ADS)

Friend, James; Yeo, Leslie; Li, Haiyan

2007-11-01

A rapid particle concentration method in sessile droplets and confined fluid chambers has been developed using asymmetric surface wave propagation on a substrate upon which the droplet is placed. Nanometre-order vibration induced along the substrate at frequencies from 8 to 125 MHz generate a combination of forces upon suspended particles and the fluid droplet itself via diffraction to provide localized agglomeration of nanoparticles into microstructures, followed by rapid collection of the microstructures to a single point at the centre of the droplet in about 2 to 30 seconds. This is far faster than other currently available particle concentration mechanisms due to the large convective velocities achieved using the device. The ability to control the collection via surface wave power and the effect of scale on the collection time and scheme of agglomeration are explained via a physical model, verified using fluorescent polystyrene particles from 20 nm to 45 microns in diameter. The usefulness of the method for bioparticles is illustrated through rapid concentration of yeast and mouse mesenchymal stem cells which remain viable and functional after concentration.

A source to deliver mesoscopic particles for laser plasma studies

NASA Astrophysics Data System (ADS)

Gopal, R.; Kumar, R.; Anand, M.; Kulkarni, A.; Singh, D. P.; Krishnan, S. R.; Sharma, V.; Krishnamurthy, M.

2017-02-01

Intense ultrashort laser produced plasmas are a source for high brightness, short burst of X-rays, electrons, and high energy ions. Laser energy absorption and its disbursement strongly depend on the laser parameters and also on the initial size and shape of the target. The ability to change the shape, size, and material composition of the matter that absorbs light is of paramount importance not only from a fundamental physics point of view but also for potentially developing laser plasma sources tailored for specific applications. The idea of preparing mesoscopic particles of desired size/shape and suspending them in vacuum for laser plasma acceleration is a sparsely explored domain. In the following report we outline the development of a delivery mechanism of microparticles into an effusive jet in vacuum for laser plasma studies. We characterise the device in terms of particle density, particle size distribution, and duration of operation under conditions suitable for laser plasma studies. We also present the first results of x-ray emission from micro crystals of boric acid that extends to 100 keV even under relatively mild intensities of 1016 W/cm2.

Particle and nuclear physics instrumentation and its broad connections

DOE PAGES

Demarteau, Marcel; Lipton, Ron; Nicholson, Howard; ...

2016-12-20

Subatomic physics shares with other basic sciences the need to innovate, invent, and develop tools, techniques, and technologies to carry out its mission to explore the nature of matter, energy, space, and time. In some cases, entire detectors or technologies developed specifically for particle physics research have been adopted by other fields of research or in commercial applications. In most cases, however, the development of new devices and technologies by particle physics for its own research has added value to other fields of research or to applications beneficial to society by integrating them in the existing technologies. Thus, detector researchmore » and development has not only advanced the current state of technology for particle physics, but has often advanced research in other fields of science and has underpinned progress in numerous applications in medicine and national security. At the same time particle physics has profited immensely from developments in industry and applied them to great benefit for the use of particle physics detectors. Finally, this symbiotic relationship has seen strong mutual benefits with sometimes unexpected far reach.« less

Particle and nuclear physics instrumentation and its broad connections

NASA Astrophysics Data System (ADS)

Demarteau, M.; Lipton, R.; Nicholson, H.; Shipsey, I.

2016-10-01

Subatomic physics shares with other basic sciences the need to innovate, invent, and develop tools, techniques, and technologies to carry out its mission to explore the nature of matter, energy, space, and time. In some cases, entire detectors or technologies developed specifically for particle physics research have been adopted by other fields of research or in commercial applications. In most cases, however, the development of new devices and technologies by particle physics for its own research has added value to other fields of research or to applications beneficial to society by integrating them in the existing technologies. Thus, detector research and development has not only advanced the current state of technology for particle physics, but has often advanced research in other fields of science and has underpinned progress in numerous applications in medicine and national security. At the same time particle physics has profited immensely from developments in industry and applied them to great benefit for the use of particle physics detectors. This symbiotic relationship has seen strong mutual benefits with sometimes unexpected far reach.

Particle and nuclear physics instrumentation and its broad connections

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

Demarteau, Marcel; Lipton, Ron; Nicholson, Howard

Subatomic physics shares with other basic sciences the need to innovate, invent, and develop tools, techniques, and technologies to carry out its mission to explore the nature of matter, energy, space, and time. In some cases, entire detectors or technologies developed specifically for particle physics research have been adopted by other fields of research or in commercial applications. In most cases, however, the development of new devices and technologies by particle physics for its own research has added value to other fields of research or to applications beneficial to society by integrating them in the existing technologies. Thus, detector researchmore » and development has not only advanced the current state of technology for particle physics, but has often advanced research in other fields of science and has underpinned progress in numerous applications in medicine and national security. At the same time particle physics has profited immensely from developments in industry and applied them to great benefit for the use of particle physics detectors. Finally, this symbiotic relationship has seen strong mutual benefits with sometimes unexpected far reach.« less

Singular Valence Fluctuations at a Kondo Destroyed Quantum Critical Point

NASA Astrophysics Data System (ADS)

Pixley, Jedediah; Kirchner, Stefan; Ingersent, Kevin; Si, Qimiao

2012-02-01

Recent experiments on the heavy fermion superconductor beta-YbAlB4 have indicated that this compound satisfies quantum critical scaling [1]. Motivated by the observation of mixed valency in this material [2], we study the Kondo destruction physics in the mixed-valence regime [3] of a particle-hole asymmetric Anderson impurity model with a pseudogapped density of states. In the vicinity of the quantum critical point we determine the finite temperature spin and charge susceptibilities by utilizing a continuous time quantum Monte Carlo method [4] and the numerical renormalization group. We show that this mixed-valence quantum critical point displays a Kondo breakdown effect. Furthermore, we find that both dynamic spin and charge susceptibilities obey frequency over temperature scaling, and that the static charge susceptibility diverges with a universal exponent. Possible implications of our results for beta-YbAlB4 are discussed. [1] Matsumoto et al, Science 331, 316 (2011). [2] Okawaet al, Physical Review Letters 104, 247201 (2010). [3] J. H. Pixley, S. Kirchner, Kevin Ingersent and Q. Si, arXiv:1108.5227v1 (2011). [4] M. Glossop, S. Kirchner, J. H. Pixley and Q. Si, Phys. Rev. Lett. 107, 076404 (2011).

High-quality and interactive animations of 3D time-varying vector fields.

PubMed

Helgeland, Anders; Elboth, Thomas

2006-01-01

In this paper, we present an interactive texture-based method for visualizing three-dimensional unsteady vector fields. The visualization method uses a sparse and global representation of the flow, such that it does not suffer from the same perceptual issues as is the case for visualizing dense representations. The animation is made by injecting a collection of particles evenly distributed throughout the physical domain. These particles are then tracked along their path lines. At each time step, these particles are used as seed points to generate field lines using any vector field such as the velocity field or vorticity field. In this way, the animation shows the advection of particles while each frame in the animation shows the instantaneous vector field. In order to maintain a coherent particle density and to avoid clustering as time passes, we have developed a novel particle advection strategy which produces approximately evenly-spaced field lines at each time step. To improve rendering performance, we decouple the rendering stage from the preceding stages of the visualization method. This allows interactive exploration of multiple fields simultaneously, which sets the stage for a more complete analysis of the flow field. The final display is rendered using texture-based direct volume rendering.

Störmer method for a problem of point injection of charged particles into a magnetic dipole field

NASA Astrophysics Data System (ADS)

Kolesnikov, E. K.

2017-03-01

The problem of point injection of charged particles into a magnetic dipole field was considered. Analytical expressions were obtained by the Störmer method for regions of allowed pulses of charged particles at random points of a dipole field at a set position of the point source of particles. It was found that, for a fixed location of the studied point, there was a specific structure of the coordinate space in the form of a set of seven regions, where the injector location in each region corresponded to a definite form of an allowed pulse region at the studied point. It was shown that the allowed region boundaries in four of the mentioned regions were surfaces of conic section revolution.

Concepts of nuclear α-particle condensation

NASA Astrophysics Data System (ADS)

Funaki, Y.; Horiuchi, H.; von Oertzen, W.; Röpke, G.; Schuck, P.; Tohsaki, A.; Yamada, T.

2009-12-01

Certain aspects of the recently proposed antisymmetrized α-particle product state wave function, or THSR (Tohsaki-Horiuchi-Schuck-Röpke) α-cluster wave function, for the description of the ground state in Be8, the Hoyle state in C12, and analogous states in heavier nuclei are elaborated in detail. For instance, the influence of antisymmetrization in the Hoyle state on the bosonic character of the α particles is studied carefully. It is shown to be weak. Bosonic aspects in Hoyle and similar states in other self-conjugate nuclei are, therefore, predominant. Another issue is the de Broglie wavelength of α particles in the Hoyle state, which is shown to be much larger than the inter-α distance. It is pointed out that the bosonic features of low-density α gas states have measurable consequences, one of which, enhanced multi-α decay properties, has likely already been detected. Consistent with experiment, the width of the proposed analog to the Hoyle state in O16 at the excitation energy of Ex=15.1 MeV is estimated to be very small (34 keV), lending credit to the existence of heavier Hoyle-like states. The intrinsic single-boson density matrix of a self-bound Bose system can, under physically desirable boundary conditions, be defined unambiguously. One eigenvalue then separates out, being close to the number of α particles in the system. Differences between Brink and THSR α-cluster wave functions are worked out. No cluster model of the Brink type can describe the Hoyle state with a single configuration. On the contrary, many superpositions of the Brink type are necessary, implying delocalization toward an α-product state. It is shown that single α-particle orbits in condensates of different nuclei are almost the same. It is thus argued that α-particle (quartet) antisymmetrized product states of the THSR type are a very promising novel and useful concept in nuclear physics.

A photophoretic-trap volumetric display

NASA Astrophysics Data System (ADS)

Smalley, D. E.; Nygaard, E.; Squire, K.; van Wagoner, J.; Rasmussen, J.; Gneiting, S.; Qaderi, K.; Goodsell, J.; Rogers, W.; Lindsey, M.; Costner, K.; Monk, A.; Pearson, M.; Haymore, B.; Peatross, J.

2018-01-01

Free-space volumetric displays, or displays that create luminous image points in space, are the technology that most closely resembles the three-dimensional displays of popular fiction. Such displays are capable of producing images in ‘thin air’ that are visible from almost any direction and are not subject to clipping. Clipping restricts the utility of all three-dimensional displays that modulate light at a two-dimensional surface with an edge boundary; these include holographic displays, nanophotonic arrays, plasmonic displays, lenticular or lenslet displays and all technologies in which the light scattering surface and the image point are physically separate. Here we present a free-space volumetric display based on photophoretic optical trapping that produces full-colour graphics in free space with ten-micrometre image points using persistence of vision. This display works by first isolating a cellulose particle in a photophoretic trap created by spherical and astigmatic aberrations. The trap and particle are then scanned through a display volume while being illuminated with red, green and blue light. The result is a three-dimensional image in free space with a large colour gamut, fine detail and low apparent speckle. This platform, named the Optical Trap Display, is capable of producing image geometries that are currently unobtainable with holographic and light-field technologies, such as long-throw projections, tall sandtables and ‘wrap-around’ displays.

Drift-based scrape-off particle width in X-point geometry

NASA Astrophysics Data System (ADS)

Reiser, D.; Eich, T.

2017-04-01

The Goldston heuristic estimate of the scrape-off layer width (Goldston 2012 Nucl. Fusion 52 013009) is reconsidered using a fluid description for the plasma dynamics. The basic ingredient is the inclusion of a compressible diamagnetic drift for the particle cross field transport. Instead of testing the heuristic model in a sophisticated numerical simulation including several physical mechanisms working together, the purpose of this work is to point out basic consequences for a drift-dominated cross field transport using a reduced fluid model. To evaluate the model equations and prepare them for subsequent numerical solution a specific analytical model for 2D magnetic field configurations with X-points is employed. In a first step parameter scans in high-resolution grids for isothermal plasmas are done to assess the basic formulas of the heuristic model with respect to the functional dependence of the scrape-off width on the poloidal magnetic field and plasma temperature. Particular features in the 2D-fluid calculations—especially the appearance of supersonic parallel flows and shock wave like bifurcational jumps—are discussed and can be understood partly in the framework of a reduced 1D model. The resulting semi-analytical findings might give hints for experimental proof and implementation in more elaborated fluid simulations.

Tunable particles alter macrophage uptake based on combinatorial effects of physical properties

PubMed Central

Garapaty, Anusha

2017-01-01

Abstract The ability to tune phagocytosis of particle‐based therapeutics by macrophages can enhance their delivery to macrophages or reduce their phagocytic susceptibility for delivery to non‐phagocytic cells. Since phagocytosis is affected by the physical and chemical properties of particles, it is crucial to identify any interplay between physical properties of particles in altering phagocytic interactions. The combinatorial effect of physical properties size, shape and stiffness was investigated on Fc receptor mediated macrophage interactions by fabrication of layer‐by‐layer tunable particles of constant surface chemistry. Our results highlight how changing particle stiffness affects phagocytic interaction intricately when combined with varying size or shape. Increase in size plays a dominant role over reduction in stiffness in reducing internalization by macrophages for spherical particles. Internalization of rod‐shaped, but not spherical particles, was highly dependent on stiffness. These particles demonstrate the interplay between size, shape and stiffness in interactions of Fc‐functionalized particles with macrophages during phagocytosis. PMID:29313025

NSR&D FY17 Report: CartaBlanca Capability Enhancements

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

Long, Christopher Curtis; Dhakal, Tilak Raj; Zhang, Duan Zhong

Over the last several years, particle technology in the CartaBlanca code has been matured and has been successfully applied to a wide variety of physical problems. It has been shown that the particle methods, especially Los Alamos's dual domain material point method, is capable of computing many problems involves complex physics, chemistries accompanied by large material deformations, where the traditional finite element or Eulerian method encounter significant difficulties. In FY17, the CartaBlanca code has been enhanced with physical models and numerical algorithms. We started out to compute penetration and HE safety problems. Most of the year we focused on themore » TEPLA model improvement testing against the sweeping wave experiment by Gray et al., because it was found that pore growth and material failure are essentially important for our tasks and needed to be understood for modeling the penetration and the can experiments efficiently. We extended the TEPLA mode from the point view of ensemble phase average to include the effects of nite deformation. It is shown that the assumed pore growth model in TEPLA is actually an exact result from the theory. Alone this line, we then generalized the model to include finite deformations to consider nonlinear dynamics of large deformation. The interaction between the HE product gas and the solid metal is based on the multi-velocity formation. Our preliminary numerical results suggest good agreement between the experiment and the numerical results, pending further verification. To improve the parallel processing capabilities of the CartaBlanca code, we are actively working with the Next Generation Code (NGC) project to rewrite selected packages using C++. This work is expected to continue in the following years. This effort also makes the particle technology developed with CartaBlanca project available to other part of the laboratory. Working with the NGC project and rewriting some parts of the code also given us an opportunity to improve our numerical implementations of the method and to take advantage of recently advances in the numerical methods, such as multiscale algorithms.« less

Determining the refractive index of particles using glare-point imaging technique

NASA Astrophysics Data System (ADS)

Meng, Rui; Ge, Baozhen; Lu, Qieni; Yu, Xiaoxue

2018-04-01

A method of measuring the refractive index of a particle is presented from a glare-point image. The space of a doublet image of a particle can be determined with high accuracy by using auto-correlation and Gaussian interpolation, and then the refractive index is obtained from glare-point separation, and a factor that may influence the accuracy of glare-point separation is explored. Experiments are carried out for three different kinds of particles, including polystyrene latex particles, glass beads, and water droplets, whose measuring accuracy is improved by the data fitting method. The research results show that the method presented in this paper is feasible and beneficial to applications such as spray and atmospheric composition measurements.

Tight-binding tunneling amplitude of an optical lattice

NASA Astrophysics Data System (ADS)

Arzamasovs, Maksims; Liu, Bo

2017-11-01

The particle in a periodic potential is an important topic in an undergraduate quantum mechanics curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting electrons in crystalline solids, and graduate-level research in solid-state and condensed matter physics. The interacting many-body phenomena are usually described in terms of the second quantized lattice Hamiltonians which treat single-particle physics on the level of tight-binding approximation and add interactions on top of it. The aim of this paper is to show how the tight-binding tunneling amplitude can be related to the strength of the periodic potential for the case of a cosine potential used in the burgeoning field of ultracold atoms. We show how to approach the problem of computing the tunneling amplitude of a deep lattice using the JWKB (Jeffreys-Wentzel-Kramers-Brillouin, also known as semiclassical) approximation. We also point out that care should be taken when applying the method of the linear combination of atomic orbitals (LCAO) in an optical lattice context. A summary of the exact solution in terms of Mathieu functions is also given.

35th International Conference of High Energy Physics

NASA Astrophysics Data System (ADS)

The French particle physics community is particularly proud to have been selected to host the 35th ICHEP conference in 2010 in Paris. This conference is the focal point of all our field since more than fifty years and is the reference event where all important results in particle physics cosmology and astroparticles are presented and discussed. This alone suffices to make this event very important. But in 2010, a coincidence of exceptional events will make this conference even more attractive! What is then so special about ICHEP 2010 conference? It will be the first ICHEP conference where physics results obtained at the LHC will be presented! New results about the elusive Higgs boson, or signals of physics beyond the standard model might therefore be announced at this conference! Major discoveries in other domains such as gravitational waves, neutrino telescopes, neutrino oscillations, dark matter or in the flavour sector are also possible, just to name a few. In addition , 2010 will be an important date to shape up the future of our field. Several major projects will present the status of their Conceptual or Engineering Design Reports during the conference. The International Linear Collider (ILC) Global Design Effort team will present the report corresponding to the end of their Technical Design Phase 1. The Compact Linear Collider (CLIC) will also report on its Conceptual Design Report. Other major projects such as Super B factories will also be presented. These reports together with LHC physics results will form the basis for key political decisions needed to be taken in the years to come. In summary, there can be no doubt that Paris is the place to be in summer 2010 for anyone interested in High Energy Physics and we will make every effort to make your stay as interesting and enjoyable as possible.

NASA's initial flight missions in the Small Explorer Program

NASA Technical Reports Server (NTRS)

Rasch, Nickolus O.; Brown, William W.

1989-01-01

A new component of NASA's Explorer Program has been initiated in order to provide research opportunities characterized by small, quick-turn-around, and frequent space missions. Objectives include the launching of one or two payloads per year, depending on mission cost and availability of funds and launch vehicles. The four missions chosen from the proposals solicited by the Small Explorer Announcement Opportunity are discussed in detail. These include the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) designed to carry out energetic particle studies of outstanding questions in the fields of space plasma, solar, heliospheric, cosmic ray, and middle atmospheric physics; the Submillimeter Wave Astronomy Satellite (SWAS), which will conduct both pointed and survey observations of dense galactic molecular clouds; the Fast Auroral Snapshot Explorer (FAST); and the Total Ozone Mapping Spectrometer (TOMS).

Teaching Elementary Particle Physics: Part I

ERIC Educational Resources Information Center

Hobson, Art

2011-01-01

I'll outline suggestions for teaching elementary particle physics, often called "high energy physics," in high school or introductory college courses for non-scientists or scientists. Some presentations of this topic simply list the various particles along with their properties, with little overarching structure. Such a laundry list approach is a…

The Ultimate Structure of Matter: The High Energy Physics Program from the 1950s through the 1980s

DOE R&D Accomplishments Database

1990-02-01

This discusses the following topics in High Energy Physics: The Particle Zoo; The Strong and the Weak; The Particle Explosion; Deep Inside the Nucleon; The Search for Unity; Physics in Collision; The Standard Model; Particles and the Cosmos; and Practical Benefits.

Computer Simulations for Lab Experiences in Secondary Physics

ERIC Educational Resources Information Center

Murphy, David Shannon

2012-01-01

Physical science instruction often involves modeling natural systems, such as electricity that possess particles which are invisible to the unaided eye. The effect of these particles' motion is observable, but the particles are not directly observable to humans. Simulations have been developed in physics, chemistry and biology that, under certain…

[Meta-analyses of quarks, baryons and mesons--a "Cochrane Collaboration" in particle physics].

PubMed

Sauerland, Stefan; Sauerland, Thankmar; Antes, Gerd; Barnett, R Michael

2002-02-01

Within the last 20 years meta-analysis has become an important research technique in medicine for integrating the results of independent studies. Meta-analytical techniques, however, are much older. In particle physics for 50 years now the properties of huge numbers of particles have been assessed in meta-analyses. The Cochrane Collaboration's counterpart in physics is the Particle Data Group. This article compares methodological and organisational aspects of meta-analyses in medicine and physics. Several interesting parallels exist, especially with regard to methodology.

ALICE Masterclass on strangeness

NASA Astrophysics Data System (ADS)

Foka, Panagiota; Janik, Małgorzata

2014-04-01

An educational activity, the International Particle Physics Masterclasses, was developed by the International Particle Physics Outreach Group with the aim to bring the excitement of cutting-edge particle-physics research into the classroom. Thousands of pupils, every year since 2005, in many countries all over the world, are hosted in research centers or universities close to their schools and become "scientists for a day" as they are introduced to the mysteries of particle physics. The program of a typical day includes lectures that give insight to topics and methods of fundamental research followed by a "hands-on" session where the high-school students perform themselves measurements on real data from particle-physics experiments. The last three years data from the ALICE experiment at LHC were used. The performed measurement "strangeness enhancement" and the employed methodology are presented.

The influence of swarm deformation on the velocity behavior of falling swarms of particles

NASA Astrophysics Data System (ADS)

Mitchell, C. A.; Pyrak-Nolte, L. J.; Nitsche, L.

2017-12-01

Cohesive particle swarms have been shown to exhibit enhanced sedimentation in fractures for an optimal range of fracture apertures. Within this range, swarms travel farther and faster than a disperse (particulate) solution. This study aims to uncover the physics underlying the enhanced sedimentation. Swarm behavior at low Reynolds number in a quiescent unbounded fluid and between smooth rigid planar boundaries is investigated numerically using direct-summation, particle-mesh (PM) and particle-particle particle-mesh (P3M) methods - based upon mutually interacting viscous point forces (Stokeslet fields). Wall effects are treated with a least-squares boundary singularity method. Sub-structural effects beyond pseudo-liquid behavior (i.e., particle-scale interactions) are approximated by the P3M method much more efficiently than with direct summation. The model parameters are selected from particle swarm experiments to enable comparison. From the simulations, if the initial swarm geometry at release is unaffected by the fracture aperture, no enhanced transport occurs. The swarm velocity as a function of apertures increases monotonically until it asymptotes to the swarm velocity in an open tank. However, if the fracture aperture affects the initial swarm geometry, the swarm velocity no longer exhibits a monotonic behavior. When swarms are released between two parallel smooth walls with very small apertures, the swarm is forced to reorganize and quickly deform, which results in dramatically reduced swarm velocities. At large apertures, the swarm evolution is similar to that of a swarm in open tank and quickly flattens into a slow speed torus. In the optimal aperture range, the swarm maintains a cohesive unit behaving similarly to a falling sphere. Swarms falling in apertures less than or greater than the optimal aperture range, experience a level of anisotropy that considerably decreases velocities. Unraveling the physics that drives swarm behavior in fractured porous media is important for understanding particle sedimentation and contaminant spreading in the subsurface. Acknowledgment: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022).

The attainment of large accelerating gradients using near field synchrotron radiation

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

Decker, G.

1989-10-15

Lienard-Wiechert potentials are used to find the electromagnetic field everywhere in free space resulting from a point charge moving on a helical trajectory. The total power emitted as synchrotron radiation from a particle on a circular path is calculated. The point charge results are generalized to the case of a line charge, and formulae are presented which can easily be evaluated numerically. A useful gradient of 80 MeV/m per kA of peak driving beam current over a distance of 1 cm is calculated using two 5 MeV driving beams moving on 1 cm radius helical orbits with bunch length 1more » mm. {copyright} 1989 American Institute of Physics« less

Physicochemical characterization of particulate emissions from a compression ignition engine employing two injection technologies and three fuels.

PubMed

Surawski, N C; Miljevic, B; Ayoko, G A; Roberts, B A; Elbagir, S; Fairfull-Smith, K E; Bottle, S E; Ristovski, Z D

2011-07-01

Alternative fuels and injection technologies are a necessary component of particulate emission reduction strategies for compression ignition engines. Consequently, this study undertakes a physicochemical characterization of diesel particulate matter (DPM) for engines equipped with alternative injection technologies (direct injection and common rail) and alternative fuels (ultra low sulfur diesel, a 20% biodiesel blend, and a synthetic diesel). Particle physical properties were addressed by measuring particle number size distributions, and particle chemical properties were addressed by measuring polycyclic aromatic hydrocarbons (PAHs) and reactive oxygen species (ROS). Particle volatility was determined by passing the polydisperse size distribution through a thermodenuder set to 300 °C. The results from this study, conducted over a four point test cycle, showed that both fuel type and injection technology have an impact on particle emissions, but injection technology was the more important factor. Significant particle number emission (54%-84%) reductions were achieved at half load operation (1% increase-43% decrease at full load) with the common rail injection system; however, the particles had a significantly higher PAH fraction (by a factor of 2 to 4) and ROS concentrations (by a factor of 6 to 16) both expressed on a test-cycle averaged basis. The results of this study have significant implications for the health effects of DPM emissions from both direct injection and common rail engines utilizing various alternative fuels.

[Adhesive properties and related phenomena for powdered pharmaceuticals].

PubMed

Otsuka, A

1998-04-01

This report deals with adhesive properties and related phenomena of powdered materials including pharmaceuticals. The adhesive force between a powder particle and substrate as well as the tensile strength of a powder bed and tablet was measured. Various factors were found to affect powder adhesion. Physical properties such as the size, shape and surface roughness were examined. The adhesive force between a particle and substrate decreased remarkably in the presence of ultrafine particles, which is of interest since the addition of adequate amount of "glidant" causes an increase in powder fluidity. From a pharmaceutical point of view, temperature and humidity were essential to particle adhesion. For several organic substances, the adhesive force increased significantly at homologous temperatures more than ca. 0.7, suggesting the sintering mechanism to be operative. The adhsive force between polymer films and glass beads varied according to polymer and relative humidity. A close correlation of water sorbed by the polymer film with adhesive force was noted. In connection with powder fluidity, compaction properties were studied by the centrifugal and tapping methods. Apparent adhesion defined as the ratio of the adhesive force between two contacting particles to the external force acting on a particle was noted to be the primary determinant of the void fraction or the porosity of the powder bed, indicating that the probability of particle displacement essentially depended on apparent adhesion.

Physics of a rapid CD4 lymphocyte count with colloidal gold.

PubMed

Hansen, P; Barry, D; Restell, A; Sylvia, D; Magnin, O; Dombkowski, D; Preffer, F

2012-03-01

The inherent surface charges and small diameters that confer colloidal stability to gold particle conjugates (immunogold) are detrimental to rapid cell surface labeling and distinct cluster definition in flow cytometric light scatter assays. Although the inherent immunogold surface charge prevents self aggregation when stored in liquid suspension, it also slows binding to cells to timeframes of hours and inhibits cell surface coverage. Although the small diameter of immunogold particles prevents settling when in liquid suspension, small particles have small light scattering cross sections and weak light scatter signals. We report a new, small particle lyophilized immunogold reagent that maintains activity after 42°C storage for a year and can be rapidly dissolved into stable liquid suspension for use in labelling cells with larger particle aggregates that have enhanced scattering cross section. Labeling requires less than 1 min at 20°C, which is ∼30 times faster than customary fluorescent antibody labeling. The labeling step involves neutralizing the surface charge of immunogold and creating specifically bound aggregates of gold on the cell surface. This process provides distinct side-scatter cluster separation with blue laser light at 488 nm, which is further improved by using red laser light at 640 nm. Similar comparisons using LED light sources showed less improvement with red light, thereby indicating that coherent light scatter is of significance in enhancing side-scatter cluster separation. The physical principles elucidated here for this technique are compatible with most flow cytometers; however, future studies of its clinical efficacy should be of primary interest in point-of-care applications where robust reagents and rapid results are important. Copyright © 2011 International Society for Advancement of Cytometry.

Mutual interactions of phonons, rotons, and gravity

NASA Astrophysics Data System (ADS)

Nicolis, Alberto; Penco, Riccardo

2018-04-01

We introduce an effective point-particle action for generic particles living in a zero-temperature superfluid. This action describes the motion of the particles in the medium at equilibrium as well as their couplings to sound waves and generic fluid flows. While we place the emphasis on elementary excitations such as phonons and rotons, our formalism applies also to macroscopic objects such as vortex rings and rigid bodies interacting with long-wavelength fluid modes. Within our approach, we reproduce phonon decay and phonon-phonon scattering as predicted using a purely field-theoretic description of phonons. We also correct classic results by Landau and Khalatnikov on roton-phonon scattering. Finally, we discuss how phonons and rotons couple to gravity, and show that the former tend to float while the latter tend to sink but with rather peculiar trajectories. Our formalism can be easily extended to include (general) relativistic effects and couplings to additional matter fields. As such, it can be relevant in contexts as diverse as neutron star physics and light dark matter detection.

The eikonal function: the commom concept in ray optics and particle mechanics

NASA Astrophysics Data System (ADS)

Krautter, Martin

1993-04-01

The habit of teaching the movements of masses first, and propagation of light later, as an electromagnetic phenomenon was widespread. Looking further back into the history of physics, however, we see earlier the concepts for understanding light rays, and later their successful application to particle trajectories, leading to the highly developed celestial mechanics towards the end of the 19th century. And then, 1905, Karl Schwarzschild transferred the technique of `canonical coordinates,' named so by C.G.J. Jacobi in 1837, back to light rays in imaging systems. I would like to point to the chief steps in the evolution. The learning process for handling both particle and wave propagation aspects continues up to our time: Richard Feynman 1918 - 1988. We may judge each contribution: whether it opens our mind to a unifying theory, or whether it hardens partial understanding. And we can notice where the understanding of light propagation led the evolution, and how the theory for movement of masses caught up.

Localization in quantum field theory

NASA Astrophysics Data System (ADS)

Balachandran, A. P.

In non-relativistic quantum mechanics, Born’s principle of localization is as follows: For a single particle, if a wave function ψK vanishes outside a spatial region K, it is said to be localized in K. In particular, if a spatial region K‧ is disjoint from K, a wave function ψK‧ localized in K‧ is orthogonal to ψK. Such a principle of localization does not exist compatibly with relativity and causality in quantum field theory (QFT) (Newton and Wigner) or interacting point particles (Currie, Jordan and Sudarshan). It is replaced by symplectic localization of observables as shown by Brunetti, Guido and Longo, Schroer and others. This localization gives a simple derivation of the spin-statistics theorem and the Unruh effect, and shows how to construct quantum fields for anyons and for massless particles with “continuous” spin. This review outlines the basic principles underlying symplectic localization and shows or mentions its deep implications. In particular, it has the potential to affect relativistic quantum information theory and black hole physics.

Augmented standard model and the simplest scenario

NASA Astrophysics Data System (ADS)

Wu, Tai Tsun; Wu, Sau Lan

2015-11-01

The experimental discovery of the Higgs particle in 2012 by the ATLAS Collaboration and the CMS Collaboration at CERN ushers in a new era of particle physics. On the basis of these data, scalar quarks and scalar leptons are added to each generation of quarks and leptons. The resulting augmented standard model has fermion-boson symmetry for each of three generations, but only one Higgs doublet giving masses to all the elementary particles. A specific special case, the simplest scenario, is studied in detail. In this case, there are twenty six quadratic divergences, and all these divergences are cancelled provided that one single relation between the masses is satisfied. This mass relation contains a great deal of information, and in particular determines the masses of all the right-handed scalar quarks and scalar leptons, while gives relations for the masses of the left-handed ones. An alternative procedure is also given with a different starting point and less reliance on the experimental data. The result is of course the same.

Group theoretical formulation of free fall and projectile motion

NASA Astrophysics Data System (ADS)

Düztaş, Koray

2018-07-01

In this work we formulate the group theoretical description of free fall and projectile motion. We show that the kinematic equations for constant acceleration form a one parameter group acting on a phase space. We define the group elements ϕ t by their action on the points in the phase space. We also generalize this approach to projectile motion. We evaluate the group orbits regarding their relations to the physical orbits of particles and unphysical solutions. We note that the group theoretical formulation does not apply to more general cases involving a time-dependent acceleration. This method improves our understanding of the constant acceleration problem with its global approach. It is especially beneficial for students who want to pursue a career in theoretical physics.

Leptoquarks in Flavour Physics

NASA Astrophysics Data System (ADS)

Müller, Dario

2018-05-01

While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in b ⟶ sℓ+ and b ⟶ c-ℓν. In this context, also the discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation. Here we discuss how these hints for new physics can also be explained by introducing leptoquarks as an extension of the Standard Model. Indeed, leptoquarks are good candidates to explain the anomaly in the anomalous magnetic moment of the muon because of an mg/mμ enhanced contribution giving correlated effects in Z boson decays which is particularly interesting in the light of future precision experiments.

Dual Vector Spaces and Physical Singularities

NASA Astrophysics Data System (ADS)

Rowlands, Peter

Though we often refer to 3-D vector space as constructed from points, there is no mechanism from within its definition for doing this. In particular, space, on its own, cannot accommodate the singularities that we call fundamental particles. This requires a commutative combination of space as we know it with another 3-D vector space, which is dual to the first (in a physical sense). The combination of the two spaces generates a nilpotent quantum mechanics/quantum field theory, which incorporates exact supersymmetry and ultimately removes the anomalies due to self-interaction. Among the many natural consequences of the dual space formalism are half-integral spin for fermions, zitterbewegung, Berry phase and a zero norm Berwald-Moor metric for fermionic states.

Three-Dimensional Visualization of Particle Tracks.

ERIC Educational Resources Information Center

Julian, Glenn M.

1993-01-01

Suggests ways to bring home to the introductory physics student some of the excitement of recent discoveries in particle physics. Describes particle detectors and encourages the use of the Standard Model along with real images of particle tracks to determine three-dimensional views of tracks. (MVL)

Displacement fields from point cloud data: Application of particle imaging velocimetry to landslide geodesy

USGS Publications Warehouse

Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.; Bawden, Gerald W.; Pawlak, Geno

2012-01-01

Acquiring spatially continuous ground-surface displacement fields from Terrestrial Laser Scanners (TLS) will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales. Problems arise, however, when estimating continuous displacement fields from TLS point-clouds because reflecting points from sequential scans of moving ground are not defined uniquely, thus repeat TLS surveys typically do not track individual reflectors. Here, we implemented the cross-correlation-based Particle Image Velocimetry (PIV) method to derive a surface deformation field using TLS point-cloud data. We estimated associated errors using the shape of the cross-correlation function and tested the method's performance with synthetic displacements applied to a TLS point cloud. We applied the method to the toe of the episodically active Cleveland Corral Landslide in northern California using TLS data acquired in June 2005–January 2007 and January–May 2010. Estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9% root mean squared (RMS) error. For each of the time periods, the method provided a smooth, nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference. For the 2010 data set, for instance, the PIV-derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone. Additionally, the upslope and downslope displacement gradients delineated by the dense PIV field elucidated the non-rigid behavior of the slide.

Two-color Fermi-liquid theory for transport through a multilevel Kondo impurity

NASA Astrophysics Data System (ADS)

Karki, D. B.; Mora, Christophe; von Delft, Jan; Kiselev, Mikhail N.

2018-05-01

We consider a quantum dot with K ≥2 orbital levels occupied by two electrons connected to two electric terminals. The generic model is given by a multilevel Anderson Hamiltonian. The weak-coupling theory at the particle-hole symmetric point is governed by a two-channel S =1 Kondo model characterized by intrinsic channels asymmetry. Based on a conformal field theory approach we derived an effective Hamiltonian at a strong-coupling fixed point. The Hamiltonian capturing the low-energy physics of a two-stage Kondo screening represents the quantum impurity by a two-color local Fermi liquid. Using nonequilibrium (Keldysh) perturbation theory around the strong-coupling fixed point we analyze the transport properties of the model at finite temperature, Zeeman magnetic field, and source-drain voltage applied across the quantum dot. We compute the Fermi-liquid transport constants and discuss different universality classes associated with emergent symmetries.

Fermilab | Mu2e

Science.gov Websites

Interactions.org Particle Physics News Image Bank Fermilab in the News Quantum Diaries Mu2e: muon-to-electron works The Mu2e detector is a particle physics detector embedded in a series of superconducting magnets advance research at the Intensity Frontier. The U.S. Particle Physics Project Prioritization Panel, P5

History of Particle Physics

Science.gov Websites

back to history page Back Particle Physics Timeline For over two thousand years people have thought the Standard Model. We invite you to explore this history of particle physics with a focus on the : Quantum Theory 1964 - Present: The Modern View (the Standard Model) back to history page Back Sections of

Quarked!--Adventures in Particle Physics Education

ERIC Educational Resources Information Center

MacDonald, Teresa; Bean, Alice

2009-01-01

Particle physics is a subject that can send shivers down the spines of students and educators alike--with visions of long mathematical equations and inscrutable ideas. This perception, along with a full curriculum, often leaves this topic the road less traveled until the latter years of school. Particle physics, including quarks, is typically not…

Let's Have a Coffee with the Standard Model of Particle Physics!

ERIC Educational Resources Information Center

Woithe, Julia; Wiener, Gerfried J.; Van der Veken, Frederik F.

2017-01-01

The Standard Model of particle physics is one of the most successful theories in physics and describes the fundamental interactions between elementary particles. It is encoded in a compact description, the so-called "Lagrangian," which even fits on t-shirts and coffee mugs. This mathematical formulation, however, is complex and only…

On some physical and dynamical properties of microplastic particles in marine environment.

PubMed

Chubarenko, I; Bagaev, A; Zobkov, M; Esiukova, E

2016-07-15

Simplified physical models and geometrical considerations reveal general physical and dynamical properties of microplastic particles (0.5-5mm) of different density, shape and size in marine environment. Windage of extremely light foamed particles, surface area and fouling rate of slightly positively buoyant microplastic spheres, films and fibres and settling velocities of negatively buoyant particles are analysed. For the Baltic Sea dimensions and under the considered idealised external conditions, (i) only one day is required for a foamed polystyrene particle to cross the sea (ca. 250km); (ii) polyethylene fibres should spend about 6-8months in the euphotic zone before sinking due to bio-fouling, whilst spherical particles can be retained on the surface up to 10-15years; (iii) for heavy microplastic particles, the time of settling through the water column in the central Gotland basin (ca. 250m) is less than 18h. Proper physical setting of the problem of microplastics transport and developing of physically-based parameterisations are seen as applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Two-dimensional colloidal metal chalcogenides semiconductors: synthesis, spectroscopy, and applications.

PubMed

Lhuillier, Emmanuel; Pedetti, Silvia; Ithurria, Sandrine; Nadal, Brice; Heuclin, Hadrien; Dubertret, Benoit

2015-01-20

CONSPECTUS: Semiconductors are at the basis of electronics. Up to now, most devices that contain semiconductors use materials obtained from a top down approach with semiconductors grown by molecular beam epitaxy or chemical vapor deposition. Colloidal semiconductor nanoparticles have been synthesized for more than 30 years now, and their synthesis is becoming mature enough that these nanoparticles have started to be incorporated into devices. An important development that recently took place in the field of colloidal quantum dots is the synthesis of two-dimensional (2D) semiconductor nanoplatelets that appear as free-standing nanosheets. These 2D colloidal systems are the newborn in the family of shaped-controlled nanoparticles that started with spheres, was extended with rods and wires, continued with tetrapods, and now ends with platelets. From a physical point of view, these objects bring 1D-confined particles into the colloidal family. It is a notable addition, since these platelets can have a thickness that is controlled with atomic precision, so that no inhomogeneous broadening is observed. Because they have two large free interfaces, mirror charges play an important role, and the binding energy of the exciton is extremely large. These two effects almost perfectly compensate each other, it results in particles with unique spectroscopic properties such as fast fluorescent lifetimes and extreme color purity (narrow full width at half-maximum of their emission spectra). These nanoplatelets with extremely large confinement but very simple and well-defined chemistry are model systems to check and further develop, notably with the incorporation in the models of the organic/inorganic interface, various theoretical approaches used for colloidal particles. From a chemical point of view, these colloidal particles are a model system to study the role of ligands since they have precisely defined facets. In addition, the synthesis of these highly anisotropic objects triggered new research to understand at a mechanistic level how this strong anisotropy could be generated. Luckily, some of the chemical know-how built with the spherical and rod-shaped particles is being transferred, with some adaptation, to 2D systems, so that 2D core/shell and core/crown heterostructures have recently been introduced. These objects are very interesting because they suggest that multiple quantum wells could be grown in solution. From the application point of view, 2D colloidal nanoplatelets offer interesting perspectives when color purity, charge conductivity, or field tunable absorption are required. In this Account, we review the chemical synthesis, the physical properties, and the applications of colloidal semiconductor nanoplatelets with an emphasis on the zinc-blende nanoplatelets that were developed more specifically in our group.

Quantum Mechanics, vacuum, particles, Gödel-Cohen incompleteness and the Universe

NASA Astrophysics Data System (ADS)

Gonzalez-Mestres, Luis

2017-12-01

Are the standard laws of Physics really fundamental principles? Does the physical vacuum have a more primordial internal structure? Are quarks, leptons, gauge bosons… ultimate elementary objects? These three basic questions are actually closely related. If the deep vacuum structure and dynamics turn out to be less trivial than usually depicted, the conventional "elementary" particles will most likely be excitations of such a vacuum dynamics that remains by now unknown. We then expect relativity and quantum mechanics to be low-energy limits of a more fundamental dynamical pattern that generates them at a deeper level. It may even happen that vacuum drives the expansion of the Universe from its own inner dynamics. Inside such a vacuum structure, the speed of light would not be the critical speed for vacuum constituents and propagating signals. The natural scenario would be the superbradyon (superluminal preon) pattern we postulated in 1995, with a new critical speed cs much larger than the speed of light c just as c is much larger than the speed of sound. Superbradyons are assumed to be the bradyons of a super-relativity associated to cs (a Lorentz invariance with cs as the critical speed). Similarly, the standard relativistic space-time with four real coordinates would not necessarily hold beyond low-energy and comparatively local distance scales. Instead, the spinorial space-time (SST) with two complex coordinates we introduced in 1996-97 may be the suitable one to describe the internal structure of vacuum and standard "elementary" particles and, simultaneously, Cosmology at very large distance scales. If the constituents of the preonic vacuum are superluminal, quantum entanglement appears as a natural property provided cs ≫ c . The value of cs can even be possibly found experimentally by studying entanglement at large distances. It is not excluded that preonic constituents of vacuum can exist in our Universe as free particles ("free" superbradyons), in which case we expect them to be weakly coupled to standard matter. If a preonic vacuum is actually leading the basic dynamics of Particle Physics and Cosmology, and standard particles are vacuum excitations, the Gödel-Cohen incompleteness will apply to vacuum dynamics whereas the conventional laws of physics will actually be approximate and have error bars. We discuss here the possible role of the superbradyonic vacuum and of the SST in generating Quantum Mechanics, as well as the implications of such a dynamical origin of the conventional laws of Physics and possible evidences in experiments and observations. Black holes, gravitational waves, possible "free" superbradyons or preonic waves, unconventional vacuum radiation… are considered from this point of view paying particular attention to LIGO, VIRGO and CERN experiments. This lecture is dedicated to the memory of John Bell

Exploring the role of turbulent acceleration and heating in fractal current sheet of solar flares­ from hybrid particle in cell and lattice Boltzmann virtual test

NASA Astrophysics Data System (ADS)

Zhu, B.; Lin, J.; Yuan, X.; Li, Y.; Shen, C.

2016-12-01

The role of turbulent acceleration and heating in the fractal magnetic reconnection of solar flares is still not clear, especially at the X-point in the diffusion region. At virtual test aspect, it is hardly to quantitatively analyze the vortex generation, turbulence evolution, particle acceleration and heating in the magnetic islands coalesce in fractal manner, formatting into largest plasmid and ejection process in diffusion region through classical magnetohydrodynamics numerical method. With the development of physical particle numerical method (particle in cell method [PIC], Lattice Boltzmann method [LBM]) and high performance computing technology in recently two decades. Kinetic simulation has developed into an effectively manner to exploring the role of magnetic field and electric field turbulence in charged particles acceleration and heating process, since all the physical aspects relating to turbulent reconnection are taken into account. In this paper, the LBM based lattice DxQy grid and extended distribution are added into charged-particles-to-grid-interpolation of PIC based finite difference time domain scheme and Yee Grid, the hybrid PIC-LBM simulation tool is developed to investigating turbulence acceleration on TIANHE-2. The actual solar coronal condition (L≈105Km,B≈50-500G,T≈5×106K, n≈108-109, mi/me≈500-1836) is applied to study the turbulent acceleration and heating in solar flare fractal current sheet. At stage I, magnetic islands shrink due to magnetic tension forces, the process of island shrinking halts when the kinetic energy of the accelerated particles is sufficient to halt the further collapse due to magnetic tension forces, the particle energy gain is naturally a large fraction of the released magnetic energy. At stage II and III, the particles from the energized group come in to the center of the diffusion region and stay longer in the area. In contract, the particles from non energized group only skim the outer part of the diffusion regions. At stage IV, the magnetic reconnection type nanoplasmid (200km) stop expanding and carrying enough energy to eject particles as constant velocity. Last, the role of magnetic field turbulence and electric field turbulence in electron and ion acceleration at the diffusion regions in solar flare fractural current sheet is given.

Soft matter strategies for controlling food texture: formation of hydrogel particles by biopolymer complex coacervation

NASA Astrophysics Data System (ADS)

Wu, Bi-cheng; Degner, Brian; McClements, David Julian

2014-11-01

Soft matter physics principles can be used to address important problems in the food industry. Starch granules are widely used in foods to create desirable textural attributes, but high levels of digestible starch may pose a risk of diabetes. Consequently, there is a need to find healthier replacements for starch granules. The objective of this research was to create hydrogel particles from protein and dietary fiber with similar dimensions and functional attributes as starch granules. Hydrogel particles were formed by mixing gelatin (0.5 wt%) with pectin (0 to 0.2 wt%) at pH values above the isoelectric point of the gelatin (pH 9, 30 °C). When the pH was adjusted to pH 5, the biopolymer mixture spontaneously formed micron-sized particles due to electrostatic attraction of cationic gelatin with anionic pectin through complex coacervation. Differential interference contrast (DIC) microscopy showed that the hydrogel particles were translucent and spheroid, and that their dimensions were determined by pectin concentration. At 0.01 wt% pectin, hydrogel particles with similar dimensions to swollen starch granules (D3,2 ≈ 23 µm) were formed. The resulting hydrogel suspensions had similar appearances to starch pastes and could be made to have similar textural attributes (yield stress and shear viscosity) by adjusting the effective hydrogel particle concentration. These hydrogel particles may therefore be used to improve the texture of reduced-calorie foods and thereby help tackle obesity and diabetes.

Surfing on Protein Waves: Proteophoresis as a Mechanism for Bacterial Genome Partitioning

NASA Astrophysics Data System (ADS)

Walter, J.-C.; Dorignac, J.; Lorman, V.; Rech, J.; Bouet, J.-Y.; Nollmann, M.; Palmeri, J.; Parmeggiani, A.; Geniet, F.

2017-07-01

Efficient bacterial chromosome segregation typically requires the coordinated action of a three-component machinery, fueled by adenosine triphosphate, called the partition complex. We present a phenomenological model accounting for the dynamic activity of this system that is also relevant for the physics of catalytic particles in active environments. The model is obtained by coupling simple linear reaction-diffusion equations with a proteophoresis, or "volumetric" chemophoresis, force field that arises from protein-protein interactions and provides a physically viable mechanism for complex translocation. This minimal description captures most known experimental observations: dynamic oscillations of complex components, complex separation, and subsequent symmetrical positioning. The predictions of our model are in phenomenological agreement with and provide substantial insight into recent experiments. From a nonlinear physics view point, this system explores the active separation of matter at micrometric scales with a dynamical instability between static positioning and traveling wave regimes triggered by the dynamical spontaneous breaking of rotational symmetry.

The physical impacts of microplastics on marine organisms: a review.

PubMed

Wright, Stephanie L; Thompson, Richard C; Galloway, Tamara S

2013-07-01

Plastic debris at the micro-, and potentially also the nano-scale, are widespread in the environment. Microplastics have accumulated in oceans and sediments worldwide in recent years, with maximum concentrations reaching 100 000 particles m(3). Due to their small size, microplastics may be ingested by low trophic fauna, with uncertain consequences for the health of the organism. This review focuses on marine invertebrates and their susceptibility to the physical impacts of microplastic uptake. Some of the main points discussed are (1) an evaluation of the factors contributing to the bioavailability of microplastics including size and density; (2) an assessment of the relative susceptibility of different feeding guilds; (3) an overview of the factors most likely to influence the physical impacts of microplastics such as accumulation and translocation; and (4) the trophic transfer of microplastics. These findings are important in guiding future marine litter research and management strategies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dusty (complex) plasmas: recent developments, advances, and unsolved problems

NASA Astrophysics Data System (ADS)

Popel, Sergey

The area of dusty (complex) plasma research is a vibrant subfield of plasma physics that be-longs to frontier research in physical sciences. This area is intrinsically interdisciplinary and encompasses astrophysics, planetary science, atmospheric science, magnetic fusion energy sci-ence, and various applied technologies. The research in dusty plasma started after two major discoveries in very different areas: (1) the discovery by the Voyager 2 spacecraft in 1980 of the radial spokes in Saturn's B ring, and (2) the discovery of the early 80's growth of contaminating dust particles in plasma processing. Dusty plasmas are ubiquitous in the universe; examples are proto-planetary and solar nebulae, molecular clouds, supernovae explosions, interplanetary medium, circumsolar rings, and asteroids. Within the solar system, we have planetary rings (e.g., Saturn and Jupiter), Martian atmosphere, cometary tails and comae, dust clouds on the Moon, etc. Close to the Earth, there are noctilucent clouds and polar mesospheric summer echoes, which are clouds of tiny (charged) ice particles that are formed in the summer polar mesosphere at the altitudes of about 82-95 km. Dust and dusty plasmas are also found in the vicinity of artificial satellites and space stations. Dust also turns out to be common in labo-ratory plasmas, such as in the processing of semiconductors and in tokamaks. In processing plasmas, dust particles are actually grown in the discharge from the reactive gases used to form the plasmas. An example of the relevance of industrial dusty plasmas is the growth of silicon microcrystals for improved solar cells in the future. In fact, nanostructured polymorphous sili-con films provide solar cells with high and time stable efficiency. These nano-materials can also be used for the fabrication of ultra-large-scale integration circuits, display devices, single elec-tron devices, light emitting diodes, laser diodes, and others. In microelectronic industries, dust has to be kept under control in the manufacture of microchips, otherwise charged dust particles (also known as killer particles) can destroy electronic circuits. In magnetic fusion research using tokamaks, one realizes that the absorption of tritium by dust fragments could cause a serious health hazard. The evaporation of dust particles could also lead to bremsstrahlung adversely affecting the energy gain of the tokamaks or other fusion devices. The specific features of dusty plasmas are a possibility of the formation of dust Coulomb lattices and the anomalous dissi-pation arising due to the interplay between plasmas and charged dust grains. These features determine new physics of dusty plasmas including, in particular, phase transitions and critical point phenomena, wave propagation, nonlinear effects and turbulence, dissipative and coherent structures, etc. The present review covers the main aspects of the area of dusty (complex) plasma research. The author acknowledges the financial support of the Division of Earth Sci-ences, Russian Academy of Sciences (the basic research program "Nanoscale particles in nature and technogenic products: conditions of existence, physical and chemical properties, and mech-anisms of formation"'), of the Division of Physical Sciences, Russian Academy of Sciences (the basic research program "Plasma physics in the Solar system"), of the Dynasty Foundation, as well as of the Russian Foundation for Basic Research.

A Neutral Particle Analyser Proposed On Board Bepicolombo Planetary Orbiter: Serena (searching For Exospheric Refilling and Emitted Neutral Abundances)

NASA Astrophysics Data System (ADS)

Orsini, S.; Npa-Serena Team

The Neutral Particle Analyser SERENA, proposed on board the BepiColombo Mer- cury Planetary Orbiter (MPO), has the purpose of investigating the Hermean exo- spheric and energetic neutral populations. Local and detailed analysis of the exo- spheric composition will be performed by a ram-pointing sensor (MAIA), while en- ergetic neutrals produced through sputtering and charge-exchange processes will be collected by two nadir-pointing sensors (L-ENA, MH-ENA). A central problem in the understanding of the evolution of solar system bodies is the role played by the so- lar wind, solar radiation and micro-meteorite bombardment in controlling mass losses. The direct in situ detection of the Hermean exosphere, the gas evolving from the planet as a product of the different physical processes acting onto the surface, is of crucial importance to understand the past and present evolution of the crust. Current knowl- edge of the origin and evolution of the solar system is based on detailed measurement of chemical, elemental, and isotopic composition of matter. The proposed instrument suite is unique in its capability to perform quantitative analysis and resolve exospheric gas composition under all these three aspects. The value of neutral particles mea- surements for getting a comprehensive picture of the solar wind-planets interaction has been appreciated since the late eighties. Comparison of the measurements in the Mercury environment with those achieved by neutral particle imagers already flying around Earth (IMAGE), Mars (Mars Express), Jupiter and Saturn (Cassini) will allow comparative investigations of evolution and dynamics of planetary magnetospheres.

Physical Principles of the Method for Determination of Geometrical Characteristics and Particle Recognition in Digital Holography

NASA Astrophysics Data System (ADS)

Dyomin, V. V.; Polovtsev, I. G.; Davydova, A. Yu.

2018-03-01

The physical principles of a method for determination of geometrical characteristics of particles and particle recognition based on the concepts of digital holography, followed by processing of the particle images reconstructed from the digital hologram, using the morphological parameter are reported. An example of application of this method for fast plankton particle recognition is given.

Status of Knowledge after Ulysses and SOHO: Session 2: Investigate the Links between the Solar Surface, Corona, and Inner Heliosphere.

NASA Technical Reports Server (NTRS)

Suess, Steven

2006-01-01

As spacecraft observations of the heliosphere have moved from exploration into studies of physical processes, we are learning about the linkages that exist between different parts of the system. The past fifteen years have led to new ideas for how the heliospheric magnetic field connects back to the Sun and to how that connection plays a role in the origin of the solar wind. A growing understanding these connections, in turn, has led to the ability to use composition, ionization state, the microscopic state of the in situ plasma, and energetic particles as tools to further analyze the linkages and the underlying physical processes. Many missions have contributed to these investigations of the heliosphere as an integrated system. Two of the most important are Ulysses and SOHO, because of the types of measurements they make, their specific orbits, and how they have worked to complement each other. I will review and summarize the status of knowledge about these linkages, with emphasis on results from the Ulysses and SOHO missions. Some of the topics will be the global heliosphere at sunspot maximum and minimum, the physics and morphology of coronal holes, the origin(s) of slow wind, SOHO-Ulysses quadrature observations, mysteries in the propagation of energetic particles, and the physics of eruptive events and their associated current sheets. These specific topics are selected because they point towards the investigations that will be carried out with Solar Orbiter (SO) and the opportunity will be used to illustrate how SO will uniquely contribute to our knowledge of the underlying physical processes.

On modeling weak sinks in MODPATH

USGS Publications Warehouse

Abrams, Daniel B.; Haitjema, Henk; Kauffman, Leon J.

2012-01-01

Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs.

Dark matter universe.

PubMed

Bahcall, Neta A

2015-10-06

Most of the mass in the universe is in the form of dark matter--a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations--from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is "cold" (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology--a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)--fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle.

Dark matter universe

PubMed Central

Bahcall, Neta A.

2015-01-01

Most of the mass in the universe is in the form of dark matter—a new type of nonbaryonic particle not yet detected in the laboratory or in other detection experiments. The evidence for the existence of dark matter through its gravitational impact is clear in astronomical observations—from the early observations of the large motions of galaxies in clusters and the motions of stars and gas in galaxies, to observations of the large-scale structure in the universe, gravitational lensing, and the cosmic microwave background. The extensive data consistently show the dominance of dark matter and quantify its amount and distribution, assuming general relativity is valid. The data inform us that the dark matter is nonbaryonic, is “cold” (i.e., moves nonrelativistically in the early universe), and interacts only weakly with matter other than by gravity. The current Lambda cold dark matter cosmology—a simple (but strange) flat cold dark matter model dominated by a cosmological constant Lambda, with only six basic parameters (including the density of matter and of baryons, the initial mass fluctuations amplitude and its scale dependence, and the age of the universe and of the first stars)—fits remarkably well all the accumulated data. However, what is the dark matter? This is one of the most fundamental open questions in cosmology and particle physics. Its existence requires an extension of our current understanding of particle physics or otherwise point to a modification of gravity on cosmological scales. The exploration and ultimate detection of dark matter are led by experiments for direct and indirect detection of this yet mysterious particle. PMID:26417091

Why Nature has made a choice of one time and three space coordinates?

NASA Astrophysics Data System (ADS)

Mankoc Borstnik, N.; Nielsen, H. B.

2002-12-01

We propose a possible answer to one of the most exciting open questions in physics and cosmology, that is, the question why we seem to experience four-dimensional spacetime with three ordinary and one time dimensions. Making assumptions (such as particles being in first approximation massless) about the equations of motion, we argue for restrictions on the number of space and time dimensions. Accepting our explanation of the spacetime signature and the number of dimensions would be a point supporting (further) the importance of the 'internal space'.

Design and Shielding of Radiotherapy Treatment Facilities; IPEM Report 75, 2nd Edition

NASA Astrophysics Data System (ADS)

Horton, Patrick; Eaton, David

2017-07-01

Design and Shielding of Radiotherapy Treatment Facilities provides readers with a single point of reference for protection advice to the construction and modification of radiotherapy facilities. The book assembles a faculty of national and international experts on all modalities including megavoltage and kilovoltage photons, brachytherapy and high-energy particles, and on conventional and Monte Carlo shielding calculations. This book is a comprehensive reference for qualified experts and radiation-shielding designers in radiation physics and also useful to anyone involved in the design of radiotherapy facilities.

Discrete Element Method and its application to materials failure problem on the example of Brazilian Test

NASA Astrophysics Data System (ADS)

Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Dębski, Wojciech

2017-04-01

The earthquake focus is the point where a rock under external stress starts to fracture. Understanding earthquake nucleation and earthquake dynamics requires thus understanding of fracturing of brittle materials. This, however, is a continuing problem and enduring challenge to geoscience. In spite of significant progress we still do not fully understand the failure of rock materials due to extreme stress concentration in natural condition. One of the reason of this situation is that information about natural or induced seismic events is still not sufficient for precise description of physical processes in seismic foci. One of the possibility of improving this situation is using numerical simulations - a powerful tool of contemporary physics. For this reason we used an advanced implementation of the Discrete Element Method (DEM). DEM's main task is to calculate physical properties of materials which are represented as an assembly of a great number of particles interacting with each other. We analyze the possibility of using DEM for describing materials during so called Brazilian Test. Brazilian Test is a testing method to obtain the tensile strength of brittle material. One of the primary reasons for conducting such simulations is to measure macroscopic parameters of the rock sample. We would like to report our efforts of describing the fracturing process during the Brazilian Test from the microscopic point of view and give an insight into physical processes preceding materials failure.

News

NASA Astrophysics Data System (ADS)

2002-03-01

UK Awards: Teacher of Physics Awards Institute Matters: Institute of Physics Education Conference UK Awards: Top SHAP students win prizes Competition: International creative essay competition UK Awards: Kelvin Medal Particle Physics Resources: New poster from PPARC Australia: Physics Students's Day at Adventure World UK Awards: Bragg Medal winners in a FLAP ASE Annual Meeting: Particle Physics at ASE 2002 UK Grants: PPARC Awards AAPT Winter Meeting: Physics First - but do you need maths? UK In-Service Training: The Particle Physics Institutes for A-level teachers Physics on Stage 2: Not too entertaining this time, please! Scotland: A reasoned approach wins reasonable funding Institute Matters: New education manager Germany: Physics gets real: curriculum change for better teaching Research Frontiers: Let there be light - if you hang on a minute

Applicability of low-melting-point microcrystalline wax to develop temperature-sensitive formulations.

PubMed

Matsumoto, Kohei; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

2017-10-30

Low-melting-point substances are widely used to develop temperature-sensitive formulations. In this study, we focused on microcrystalline wax (MCW) as a low-melting-point substance. We evaluated the drug release behavior of wax matrix (WM) particles using various MCW under various temperature conditions. WM particles containing acetaminophen were prepared using a spray congealing technique. In the dissolution test at 37°C, WM particles containing low-melting-point MCWs whose melting was starting at approx. 40°C (Hi-Mic-1045 or 1070) released the drug initially followed by the release of only a small amount. On the other hand, in the dissolution test at 20 and 25°C for WM particles containing Hi-Mic-1045 and at 20, 25, and 30°C for that containing Hi-Mic-1070, both WM particles showed faster drug release than at 37°C. The characteristic drug release suppression of WM particles containing low-melting-point MCWs at 37°C was thought attributable to MCW melting, as evidenced by differential scanning calorimetry analysis and powder X-ray diffraction analysis. Taken together, low-melting-point MCWs may be applicable to develop implantable temperature-sensitive formulations that drug release is accelerated by cooling at administered site. Copyright © 2017 Elsevier B.V. All rights reserved.

The International Committee for Future Accelerators (ICFA): 1976 to the present

DOE PAGES

Rubinstein, Roy

2016-12-14

The International Committee for Future Accelerators (ICFA) has been in existence now for four decades. It plays an important role in allowing discussions by the world particle physics community on the status and future of very large particle accelerators and the particle physics and related fields associated with them. Here, this paper gives some indication of what ICFA is and does, and also describes its involvement in some of the more important developments in the particle physics field since its founding.

Single Aerosol Particle Studies Using Optical Trapping Raman And Cavity Ringdown Spectroscopy

NASA Astrophysics Data System (ADS)

Gong, Z.; Wang, C.; Pan, Y. L.; Videen, G.

2017-12-01

Due to the physical and chemical complexity of aerosol particles and the interdisciplinary nature of aerosol science that involves physics, chemistry, and biology, our knowledge of aerosol particles is rather incomplete; our current understanding of aerosol particles is limited by averaged (over size, composition, shape, and orientation) and/or ensemble (over time, size, and multi-particles) measurements. Physically, single aerosol particles are the fundamental units of any large aerosol ensembles. Chemically, single aerosol particles carry individual chemical components (properties and constituents) in particle ensemble processes. Therefore, the study of single aerosol particles can bridge the gap between aerosol ensembles and bulk/surface properties and provide a hierarchical progression from a simple benchmark single-component system to a mixed-phase multicomponent system. A single aerosol particle can be an effective reactor to study heterogeneous surface chemistry in multiple phases. Latest technological advances provide exciting new opportunities to study single aerosol particles and to further develop single aerosol particle instrumentation. We present updates on our recent studies of single aerosol particles optically trapped in air using the optical-trapping Raman and cavity ringdown spectroscopy.

Georges Charpak, Particle Detectors, and Multiwire Chambers

Science.gov Websites

particle detectors used throughout experimental particle physics. In 1968, he invented and developed the the 2005 International Year of Physics (video) Top Some links on this page may take you to non-federal

Probing the frontiers of particle physics with tabletop-scale experiments.

PubMed

DeMille, David; Doyle, John M; Sushkov, Alexander O

2017-09-08

The field of particle physics is in a peculiar state. The standard model of particle theory successfully describes every fundamental particle and force observed in laboratories, yet fails to explain properties of the universe such as the existence of dark matter, the amount of dark energy, and the preponderance of matter over antimatter. Huge experiments, of increasing scale and cost, continue to search for new particles and forces that might explain these phenomena. However, these frontiers also are explored in certain smaller, laboratory-scale "tabletop" experiments. This approach uses precision measurement techniques and devices from atomic, quantum, and condensed-matter physics to detect tiny signals due to new particles or forces. Discoveries in fundamental physics may well come first from small-scale experiments of this type. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Irreversible Processes in Ionized Gases

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

Balescu, R.

1960-01-01

The general theory of irreversible processes, developed by Prigogine and Balescu, is applied to the case of long range interactions in ionized gases. A similar diagram technique permits the systematic selection of all the contributions to the evolution of the distribution function, a an order of approximation equivalent to Debye's equilibrium theory. The infinite series which appear in this way can be summed exactly. The resulting evolution equations have a clear physical significance: they describe interactions of "quasi particles," which are electrons or ions "dressed" by their polarization clouds. These clouds are not a permanent feature, as in equilibrium theory,more » but have a nonequilibrium, changing shape, distorted by the motions of the particles. From the mathematical point of view, these equations exhibit a new type of nonlinearity, which is very directly related to the collective nature of the interactions.« less

Photonic Aharonov–Bohm effect in photon–phonon interactions

PubMed Central

Li, Enbang; Eggleton, Benjamin J.; Fang, Kejie; Fan, Shanhui

2014-01-01

The Aharonov–Bohm effect is one of the most intriguing phenomena in both classical and quantum physics, and associates with a number of important and fundamental issues in quantum mechanics. The Aharonov–Bohm effects of charged particles have been experimentally demonstrated and found applications in various fields. Recently, attention has also focused on the Aharonov–Bohm effect for neutral particles, such as photons. Here we propose to utilize the photon–phonon interactions to demonstrate that photonic Aharonov–Bohm effects do exist for photons. By introducing nonreciprocal phases for photons, we observe experimentally a gauge potential for photons in the visible range based on the photon–phonon interactions in acousto-optic crystals, and demonstrate the photonic Aharonov–Bohm effect. The results presented here point to new possibilities to control and manipulate photons by designing an effective gauge potential. PMID:24476790

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

Stanislav S. Gornostayev; Jouko J. Haerkki

Examinations of polished and dry cut sections of feed and tuyere coke revealed some possible mechanisms for the physical influence of mineral compounds on the reactivity and strength of coke. It was observed that rounded particles of mineral phases that are exposed to the pore walls and surface of coke at high temperature create an inorganic cover, thus reducing the surface available for gas-solid reactions. The particles of mineral matter that have a low melting point and viscosity can affect the coke at earlier stages in the blast furnace process, acting in the upper parts of the blast furnace (BF).more » The temperature-driven redistribution of mineral phases within the coke matrix probably leads to the creation of weak spots and in general to anisotropy in its properties, thus reducing its strength. 9 refs., 2 figs., 1 tab.« less

The dark side of cosmology: dark matter and dark energy.

PubMed

Spergel, David N

2015-03-06

A simple model with only six parameters (the age of the universe, the density of atoms, the density of matter, the amplitude of the initial fluctuations, the scale dependence of this amplitude, and the epoch of first star formation) fits all of our cosmological data . Although simple, this standard model is strange. The model implies that most of the matter in our Galaxy is in the form of "dark matter," a new type of particle not yet detected in the laboratory, and most of the energy in the universe is in the form of "dark energy," energy associated with empty space. Both dark matter and dark energy require extensions to our current understanding of particle physics or point toward a breakdown of general relativity on cosmological scales. Copyright © 2015, American Association for the Advancement of Science.

A qualitative study of the complete set of solutions of the differential equation of motion of a test particle in the equatorial plane of the Kerr gravitational field

NASA Technical Reports Server (NTRS)

Montgomery, H. E.; Chan, F. K.

1973-01-01

A study is made of the mathematical solution of the differential equation of motion of a test particle in the equatorial plane of the Kerr gravitational field, using S (Schwarzschild-like) coordinates. A qualitative solution of this equation leads to the conclusion that there can only be 25 different types of orbits. For each value of a, the results are presented in a master diagram for which h and e are the parameters. A master diagram divides the h, e parameter space into regions such that at each point within one of these regions the types of admissible orbits are qualitatively the same. A pictorial representation of the physical orbits in the r, phi plane is also given.

Axion dark matter searches

DOE PAGES

Stern, Ian P.

2014-01-01

We report nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a μeV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 μeV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axionsmore » at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.« less

Particle dark matter searches in the anisotropic sky

NASA Astrophysics Data System (ADS)

Fornengo, Nicolao; Regis, Marco

2014-02-01

Anisotropies in the electromagnetic emission produced by dark matter annihilation or decay in the extragalactic sky are a recent tool in the quest for a particle dark matter evidence. We review the formalism to compute the two-point angular power spectrum in the halo-model approach and discuss the features and the relative size of the various auto- and cross-correlation signals that can be envisaged for anisotropy studies. From the side of particle dark matter signals, we consider the full multi-wavelength spectrum, from the radio emission to X-ray and gamma-ray productions. We discuss the angular power spectra of the auto-correlation of each of these signals and of the cross-correlation between any pair of them. We then extend the search to comprise specific gravitational tracers of dark matter distribution in the Universe: weak-lensing cosmic shear, large-scale-structure matter distribution and CMB-lensing. We have shown that cross-correlating a multi-wavelength dark matter signal (which is a direct manifestation of its particle physics nature) with a gravitational tracer (which is a manifestation of the presence of large amounts of unseen matter in the Universe) may offer a promising tool to demonstrate that what we call DM is indeed formed by elementary particles.

Estimating Colloidal Contact Model Parameters Using Quasi-Static Compression Simulations.

PubMed

Bürger, Vincent; Briesen, Heiko

2016-10-05

For colloidal particles interacting in suspensions, clusters, or gels, contact models should attempt to include all physical phenomena experimentally observed. One critical point when formulating a contact model is to ensure that the interaction parameters can be easily obtained from experiments. Experimental determinations of contact parameters for particles either are based on bulk measurements for simulations on the macroscopic scale or require elaborate setups for obtaining tangential parameters such as using atomic force microscopy. However, on the colloidal scale, a simple method is required to obtain all interaction parameters simultaneously. This work demonstrates that quasi-static compression of a fractal-like particle network provides all the necessary information to obtain particle interaction parameters using a simple spring-based contact model. These springs provide resistances against all degrees of freedom associated with two-particle interactions, and include critical forces or moments where such springs break, indicating a bond-breakage event. A position-based cost function is introduced to show the identifiability of the two-particle contact parameters, and a discrete, nonlinear, and non-gradient-based global optimization method (simplex with simulated annealing, SIMPSA) is used to minimize the cost function calculated from deviations of particle positions. Results show that, in principle, all necessary contact parameters for an arbitrary particle network can be identified, although numerical efficiency as well as experimental noise must be addressed when applying this method. Such an approach lays the groundwork for identifying particle-contact parameters from a position-based particle analysis for a colloidal system using just one experiment. Spring constants also directly influence the time step of the discrete-element method, and a detailed knowledge of all necessary interaction parameters will help to improve the efficiency of colloidal particle simulations.

The Birth of Elementary-Particle Physics.

ERIC Educational Resources Information Center

Brown, Laurie M.; Hoddeson, Lillian

1982-01-01

Traces the origin and development of particle physics, concentrating on the roles of cosmic rays and theory. Includes charts highlighting significant events in the development of cosmic-ray physics and quantum field theory. (SK)

Can Grade-6 Students Understand Quarks? Probing Acceptance of the Subatomic Structure of Matter with 12-Year-Olds

ERIC Educational Resources Information Center

Wiener, Gerfried J.; Schmeling, Sascha M.; Hopf, Martin

2015-01-01

This study introduces a teaching concept based on the Standard Model of particle physics. It comprises two consecutive chapters--elementary particles and fundamental interactions. The rationale of this concept is that the fundamental principles of particle physics can run as the golden thread through the whole physics curriculum. The design…

Effect of fat content on the physical properties and consumer acceptability of vanilla ice cream.

PubMed

Rolon, M Laura; Bakke, Alyssa J; Coupland, John N; Hayes, John E; Roberts, Robert F

2017-07-01

Ice cream is a complex food matrix that contains multiple physical phases. Removal of 1 ingredient may affect not only its physical properties but also multiple sensory characteristics that may or may not be important to consumers. Fat not only contributes to texture, mouth feel, and flavor, but also serves as a structural element. We evaluated the effect of replacing fat with maltodextrin (MD) on select physical properties of ice cream and on consumer acceptability. Vanilla ice creams were formulated to contain 6, 8, 10, 12, and 14% fat, and the difference was made up with 8, 6, 4, 2, and 0% maltodextrin, respectively, to balance the mix. Physical characterization included measurements of overrun, apparent viscosity, fat particle size, fat destabilization, hardness, and melting rate. A series of sensory tests were conducted to measure liking and the intensity of various attributes. Tests were also conducted after 19 weeks of storage at -18°C to assess changes in acceptance due to prolonged storage at unfavorable temperatures. Then, discrimination tests were performed to determine which differences in fat content were detectable by consumers. Mix viscosity decreased with increasing fat content and decreasing maltodextrin content. Fat particle size and fat destabilization significantly increased with increasing fat content. However, acceptability did not differ significantly across the samples for fresh or stored ice cream. Following storage, ice creams with 6, 12, and 14% fat did not differ in acceptability compared with fresh ice cream. However, the 8% fat, 6% MD and 10% fat, 4% MD ice creams showed a significant drop in acceptance after storage relative to fresh ice cream at the same fat content. Consumers were unable to detect a difference of 2 percentage points in fat level between 6 and 12% fat. They were able to detect a difference of 4 percentage points for ice creams with 6% versus 10%, but not for those with 8% versus 12% fat. Removing fat and replacing it with maltodextrin caused minimal changes in physical properties in ice cream and mix and did not change consumer acceptability for either fresh or stored ice cream. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

Ballouz, Ronald-Louis; Richardson, Derek C.; Morishima, Ryuji

We study the B ring’s complex optical depth structure. The source of this structure may be the complex dynamics of the Keplerian shear and the self-gravity of the ring particles. The outcome of these dynamic effects depends sensitively on the collisional and physical properties of the particles. Two mechanisms can emerge that dominate the macroscopic physical structure of the ring: self-gravity wakes and viscous overstability. Here we study the interplay between these two mechanisms by using our recently developed particle collision method that allows us to better model the inter-particle contact physics. We find that for a constant ring surfacemore » density and particle internal density, particles with rough surfaces tend to produce axisymmetric ring features associated with the viscous overstability, while particles with smoother surfaces produce self-gravity wakes.« less

The Fermi Large Area Telescope on Orbit: Event Classification, Instrument Response Functions, and Calibration

DTIC Science & Technology

2012-11-01

Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology , Department of Physics and SLAC National Accelerator...Laboratory, Stanford University, Stanford, CA 94305, USA; echarles@slac.stanford.edu 3 Department of Physics, Center for Cosmology and Astro-Particle Physics

Educational Information

Science.gov Websites

PDG Homepage Link Educational Information Particle Adventure Image CPEP Image Enjoy our interactive web feature: The Particle Adventure Contemporary Physics Education Projects: Educational materials educational sites on particle physics Copyright information: This page and all following and associated are

Exotic Lifshitz transitions in topological materials

NASA Astrophysics Data System (ADS)

Volovik, G. E.

2018-01-01

Topological Lifshitz transitions involve many types of topological structures in momentum and frequency-momentum spaces, such as Fermi surfaces, Dirac lines, Dirac and Weyl points, etc., each of which has its own stability-supporting topological invariant ( N_1, N_2, N_3, {\\tilde N}_3, etc.). The topology of the shape of Fermi surfaces and Dirac lines and the interconnection of objects of different dimensionalities produce a variety of Lifshitz transition classes. Lifshitz transitions have important implications for many areas of physics. To give examples, transition-related singularities can increase the superconducting transition temperature; Lifshitz transitions are the possible origin of the small masses of elementary particles in our Universe, and a black hole horizon serves as the surface of the Lifshitz transition between vacua with type-I and type-II Weyl points.

Nanoparticles, human health hazard and regulation

PubMed Central

Seaton, Anthony; Tran, Lang; Aitken, Robert; Donaldson, Kenneth

2010-01-01

New developments in technology usually entail some hazard as well as advantage to a society. Hazard of a material translates into risk by exposure of humans and/or their environment to the agent in question, and risk is reduced by control of exposure, usually guided by regulation based on understanding of the mechanisms of harm. We illustrate risks relating to the causation of diseases associated with exposure to aerosols of combustion particles and asbestos, leading to paradigms of particle toxicity, and discuss analogies with potential exposure to manufactured nanoparticles (NPs). We review the current understanding of the hazard of NPs derived from the new science of nanotoxicology and the limited research to date into human exposure to these particles. We identify gaps in knowledge relating to the properties of NPs that might determine toxicity and in understanding the most appropriate ways both to measure this in the laboratory and to assess it in the workplace. Nevertheless, we point out that physical principles governing the behaviour of such particles allow determination of practical methods of protecting those potentially exposed. Finally, we discuss the early steps towards regulation and the difficulties facing regulators in controlling potentially harmful exposures in the absence of sufficient scientific evidence. PMID:19726441

Segregating photoelastic particles in free-surface granular flows

NASA Astrophysics Data System (ADS)

Thomas, Amalia; Vriend, Nathalie; Environmental; Industrial Fluid Dynamics Team

2017-11-01

We present results from a novel experimental set-up creating 2D avalanches of photoelastic discs. Two distinct hoppers supply either monodisperse or bidisperse particles at adjustable flow-rates into a 2 meter long, narrow acrylic chute inclined at 20°. For 20-40 seconds the avalanche maintains a steady-state that accelerates and thins downstream. The chute basal roughness is variable, allowing for different flow profiles. Using a set of polarizers and a high-speed camera, we visualize and quantify the forces due to dynamic interactions between the discs using photoelastic theory. Velocity and density profiles are derived from particle tracking at different distances from the discharge point and are coarse-grained to obtain continuous fields. With the access to both force information and dynamical properties via particle-tracking, we can experimentally validate existing mu(I) and non-local rheologies. As an extension, we probe the effect of granular segregation in bimodal mixtures by using the two separate inflow hoppers. We derive the state of segregation along the avalanche channel and measure the segregation velocities of each species. This provides insight in, and a unique validation of, the fundamental physical processes that drive segregation in avalanching geometries.

Collider effects of unparticle interactions in multiphoton signals

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

Aliev, T. M.; Frank, Mariana; Turan, Ismail

2009-12-01

A new model of physics, with a hidden conformal sector which manifests itself as an unparticle coupling to standard model particles effectively through higher dimensional operators, predicts strong collider signals due to unparticle self-interactions. We perform a complete analysis of the most spectacular of these signals at the hadron collider, pp(p){yields}{gamma}{gamma}{gamma}{gamma} and {gamma}{gamma}gg. These processes can go through the three-point unparticle self-interactions as well as through some s and t channel diagrams with one and/or two unparticle exchanges. We study the contributions of individual diagrams classified with respect to the number of unparticle exchanges and discuss their effect on themore » cross sections at the Tevatron and the LHC. We also restrict the Tevatron bound on the unknown coefficient of the three-point unparticle correlator. With the availability of data from the Tevatron, and the advent of the data emerging from the LHC, these interactions can provide a clear and strong indication of unparticle physics and distinguish this model from other beyond the standard model scenarios.« less

Understanding the Magnetosphere: The Counter-intuitive Simplicity of Cosmic Electrodynamics

NASA Astrophysics Data System (ADS)

Vasyliūnas, V. M.

2008-12-01

Planetary magnetospheres exhibit an amazing variety of phenomena, unlimited in complexity if followed into endlessly fine detail. The challenge of theory is to understand this variety and complexity, ultimately by seeing how the observed effects follow from the basic equations of physics (a point emphasized by Eugene Parker). The basic equations themselves are remarkably simple, only their consequences being exceedingly complex (a point emphasized by Fred Hoyle). In this lecture I trace the development of electrodynamics as an essential ingredient of magnetospheric physics, through the three stages it has undergone to date. Stage I is the initial application of MHD concepts and constraints (sometimes phrased in equivalent single-particle terms). Stage II is the classical formulation of self-consistent coupling between magnetosphere and ionosphere. Stage III is the more recent recognition that properly elucidating time sequence and cause-effect relations requires Maxwell's equations combined with the unique constraints of large-scale plasma. Problems and controversies underlie the transition from each stage to the following. For each stage, there are specific observed aspects of the magnetosphere that can be understood at its level; also, each stage implies a specific way to formulate unresolved questions (particularly important in this age of extensive multi-point observations and ever-more-detailed numerical simulations).

Philosophy and Sociology of Science Evolution and History

NASA Astrophysics Data System (ADS)

Rosen, Joe

The following sections are included: * Concrete Versus Abstract Theoretical Models * Introduction: concrete and abstract in kepler's contribution * Einstein's theory of gravitation and mach's principle * Unitary symmetry and the structure of hadrons * Conclusion * Dedication * Symmetry, Entropy and Complexity * Introduction * Symmetry Implies Abstraction and Loss of Information * Broken Symmetries - Imposed or Spontaneous * Symmetry, Order and Information * References * Cosmological Surrealism: More Than "Eternal Reality" Is Needed * Pythagoreanism in atomic, nuclear and particle physics * Introduction: Pythagoreanism as part of the Greek scientific world view — and the three questions I will tackle * Point 1: the impact of Gersonides and Crescas, two scientific anti-Aristotelian rebels * Point 2: Kepler's spheres to Bohr's orbits — Pythagoreanisms at last! * Point 3: Aristotle to Maupertuis, Emmy Noether, Schwinger * References * Paradigm Completion For Generalized Evolutionary Theory With Application To Epistemology * Evolution Fully Generalized * Entropy: Gravity as Model * Evolution and Entropy: Measures of Complexity * Extinctions and a Balanced Evolutionary Paradigm * The Evolution of Human Society - the Age of Information as example * High-Energy Physics and the World Wide Web * Twentieth Century Epistemology has Strong (de facto) Evolutionary Elements * The discoveries towards the beginning of the XXth Century * Summary and Conclusions * References * Evolutionary Epistemology and Invalidation * Introduction * Extinctions and A New Evolutionary Paradigm * Evolutionary Epistemology - Active Mutations * Evolutionary Epistemology: Invalidation as An Extinction * References

Review of Particle Physics

NASA Astrophysics Data System (ADS)

Beringer, J.; Arguin, J.-F.; Barnett, R. M.; Copic, K.; Dahl, O.; Groom, D. E.; Lin, C.-J.; Lys, J.; Murayama, H.; Wohl, C. G.; Yao, W.-M.; Zyla, P. A.; Amsler, C.; Antonelli, M.; Asner, D. M.; Baer, H.; Band, H. R.; Basaglia, T.; Bauer, C. W.; Beatty, J. J.; Belousov, V. I.; Bergren, E.; Bernardi, G.; Bertl, W.; Bethke, S.; Bichsel, H.; Biebel, O.; Blucher, E.; Blusk, S.; Brooijmans, G.; Buchmueller, O.; Cahn, R. N.; Carena, M.; Ceccucci, A.; Chakraborty, D.; Chen, M.-C.; Chivukula, R. S.; Cowan, G.; D'Ambrosio, G.; Damour, T.; de Florian, D.; de Gouvêa, A.; DeGrand, T.; de Jong, P.; Dissertori, G.; Dobrescu, B.; Doser, M.; Drees, M.; Edwards, D. A.; Eidelman, S.; Erler, J.; Ezhela, V. V.; Fetscher, W.; Fields, B. D.; Foster, B.; Gaisser, T. K.; Garren, L.; Gerber, H.-J.; Gerbier, G.; Gherghetta, T.; Golwala, S.; Goodman, M.; Grab, C.; Gritsan, A. V.; Grivaz, J.-F.; Grünewald, M.; Gurtu, A.; Gutsche, T.; Haber, H. E.; Hagiwara, K.; Hagmann, C.; Hanhart, C.; Hashimoto, S.; Hayes, K. G.; Heffner, M.; Heltsley, B.; Hernández-Rey, J. J.; Hikasa, K.; Höcker, A.; Holder, J.; Holtkamp, A.; Huston, J.; Jackson, J. D.; Johnson, K. F.; Junk, T.; Karlen, D.; Kirkby, D.; Klein, S. R.; Klempt, E.; Kowalewski, R. V.; Krauss, F.; Kreps, M.; Krusche, B.; Kuyanov, Yu. V.; Kwon, Y.; Lahav, O.; Laiho, J.; Langacker, P.; Liddle, A.; Ligeti, Z.; Liss, T. M.; Littenberg, L.; Lugovsky, K. S.; Lugovsky, S. B.; Mannel, T.; Manohar, A. V.; Marciano, W. J.; Martin, A. D.; Masoni, A.; Matthews, J.; Milstead, D.; Miquel, R.; Mönig, K.; Moortgat, F.; Nakamura, K.; Narain, M.; Nason, P.; Navas, S.; Neubert, M.; Nevski, P.; Nir, Y.; Olive, K. A.; Pape, L.; Parsons, J.; Patrignani, C.; Peacock, J. A.; Petcov, S. T.; Piepke, A.; Pomarol, A.; Punzi, G.; Quadt, A.; Raby, S.; Raffelt, G.; Ratcliff, B. N.; Richardson, P.; Roesler, S.; Rolli, S.; Romaniouk, A.; Rosenberg, L. J.; Rosner, J. L.; Sachrajda, C. T.; Sakai, Y.; Salam, G. P.; Sarkar, S.; Sauli, F.; Schneider, O.; Scholberg, K.; Scott, D.; Seligman, W. G.; Shaevitz, M. H.; Sharpe, S. R.; Silari, M.; Sjöstrand, T.; Skands, P.; Smith, J. G.; Smoot, G. F.; Spanier, S.; Spieler, H.; Stahl, A.; Stanev, T.; Stone, S. L.; Sumiyoshi, T.; Syphers, M. J.; Takahashi, F.; Tanabashi, M.; Terning, J.; Titov, M.; Tkachenko, N. P.; Törnqvist, N. A.; Tovey, D.; Valencia, G.; van Bibber, K.; Venanzoni, G.; Vincter, M. G.; Vogel, P.; Vogt, A.; Walkowiak, W.; Walter, C. W.; Ward, D. R.; Watari, T.; Weiglein, G.; Weinberg, E. J.; Wiencke, L. R.; Wolfenstein, L.; Womersley, J.; Woody, C. L.; Workman, R. L.; Yamamoto, A.; Zeller, G. P.; Zenin, O. V.; Zhang, J.; Zhu, R.-Y.; Harper, G.; Lugovsky, V. S.; Schaffner, P.

2012-07-01

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter.A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/.The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D.This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).

Review of particle physics

DOE PAGES

Olive, K. A.

2016-10-01

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders,more » Probability and Statistics. As a result, among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation.« less

Particle astronomy and particle physics from the moon - The particle observatory

NASA Technical Reports Server (NTRS)

Wilson, Thomas L.

1990-01-01

Promising experiments from the moon using particle detectors are discussed, noting the advantage of the large flux collecting power Pc offered by the remote, stable environment of a lunar base. An observatory class of particle experiments is presented, based upon proposals at NASA's recent Stanford workshop. They vary from neutrino astronomy, particle astrophysics, and cosmic ray experiments to space physics and fundamental physics experiments such as proton decay and 'table-top' arrays. This research is background-limited on earth, and it is awkward and unrealistic in earth orbit, but is particularly suited for the moon where Pc can be quite large and the instrumentation is not subject to atmospheric erosion as it is (for large t) in low earth orbit.

Review of particle physics

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

Olive, K. A.

The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 3,062 new measurements from 721 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders,more » Probability and Statistics. As a result, among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation.« less

Advanced computations in plasma physics

NASA Astrophysics Data System (ADS)

Tang, W. M.

2002-05-01

Scientific simulation in tandem with theory and experiment is an essential tool for understanding complex plasma behavior. In this paper we review recent progress and future directions for advanced simulations in magnetically confined plasmas with illustrative examples chosen from magnetic confinement research areas such as microturbulence, magnetohydrodynamics, magnetic reconnection, and others. Significant recent progress has been made in both particle and fluid simulations of fine-scale turbulence and large-scale dynamics, giving increasingly good agreement between experimental observations and computational modeling. This was made possible by innovative advances in analytic and computational methods for developing reduced descriptions of physics phenomena spanning widely disparate temporal and spatial scales together with access to powerful new computational resources. In particular, the fusion energy science community has made excellent progress in developing advanced codes for which computer run-time and problem size scale well with the number of processors on massively parallel machines (MPP's). A good example is the effective usage of the full power of multi-teraflop (multi-trillion floating point computations per second) MPP's to produce three-dimensional, general geometry, nonlinear particle simulations which have accelerated progress in understanding the nature of turbulence self-regulation by zonal flows. It should be emphasized that these calculations, which typically utilized billions of particles for thousands of time-steps, would not have been possible without access to powerful present generation MPP computers and the associated diagnostic and visualization capabilities. In general, results from advanced simulations provide great encouragement for being able to include increasingly realistic dynamics to enable deeper physics insights into plasmas in both natural and laboratory environments. The associated scientific excitement should serve to stimulate improved cross-cutting collaborations with other fields and also to help attract bright young talent to plasma science.

Electromagnetic plasma simulation in realistic geometries

NASA Astrophysics Data System (ADS)

Brandon, S.; Ambrosiano, J. J.; Nielsen, D.

1991-08-01

Particle-in-Cell (PIC) calculations have become an indispensable tool to model the nonlinear collective behavior of charged particle species in electromagnetic fields. Traditional finite difference codes, such as CONDOR (2-D) and ARGUS (3-D), are used extensively to design experiments and develop new concepts. A wide variety of physical processes can be modeled simply and efficiently by these codes. However, experiments have become more complex. Geometrical shapes and length scales are becoming increasingly more difficult to model. Spatial resolution requirements for the electromagnetic calculation force large grids and small time steps. Many hours of CRAY YMP time may be required to complete 2-D calculation -- many more for 3-D calculations. In principle, the number of mesh points and particles need only to be increased until all relevant physical processes are resolved. In practice, the size of a calculation is limited by the computer budget. As a result, experimental design is being limited by the ability to calculate, not by the experimenters ingenuity or understanding of the physical processes involved. Several approaches to meet these computational demands are being pursued. Traditional PIC codes continue to be the major design tools. These codes are being actively maintained, optimized, and extended to handle large and more complex problems. Two new formulations are being explored to relax the geometrical constraints of the finite difference codes. A modified finite volume test code, TALUS, uses a data structure compatible with that of standard finite difference meshes. This allows a basic conformal boundary/variable grid capability to be retrofitted to CONDOR. We are also pursuing an unstructured grid finite element code, MadMax. The unstructured mesh approach provides maximum flexibility in the geometrical model while also allowing local mesh refinement.

On Defining Mass

NASA Astrophysics Data System (ADS)

Hecht, Eugene

2011-01-01

Though central to any pedagogical development of physics, the concept of mass is still not well understood. Properly defining mass has proven to be far more daunting than contemporary textbooks would have us believe. And yet today the origin of mass is one of the most aggressively pursued areas of research in all of physics. Much of the excitement surrounding the Large Hadron Collider at CERN is associated with discovering the mechanism responsible for the masses of the elementary particles. This paper will first briefly examine the leading definitions, pointing out their shortcomings. Then, utilizing relativity theory, it will propose—for consideration by the community of physicists—a conceptual definition of mass predicated on the more fundamental concept of energy, more fundamental in that everything that has mass has energy, yet not everything that has energy has mass.

The TOTEM Experiment at the CERN Large Hadron Collider

NASA Astrophysics Data System (ADS)

TOTEM Collaboration; Anelli, G.; Antchev, G.; Aspell, P.; Avati, V.; Bagliesi, M. G.; Berardi, V.; Berretti, M.; Boccone, V.; Bottigli, U.; Bozzo, M.; Brücken, E.; Buzzo, A.; Cafagna, F.; Calicchio, M.; Capurro, F.; Catanesi, M. G.; Catastini, P. L.; Cecchi, R.; Cerchi, S.; Cereseto, R.; Ciocci, M. A.; Cuneo, S.; Da Vià, C.; David, E.; Deile, M.; Dimovasili, E.; Doubrava, M.; Eggert, K.; Eremin, V.; Ferro, F.; Foussat, A.; Galuška, M.; Garcia, F.; Gherarducci, F.; Giani, S.; Greco, V.; Hasi, J.; Haug, F.; Heino, J.; Hilden, T.; Jarron, P.; Joram, C.; Kalliopuska, J.; Kaplon, J.; Kašpar, J.; Kundrát, V.; Kurvinen, K.; Lacroix, J. M.; Lami, S.; Latino, G.; Lauhakangas, R.; Lippmaa, E.; Lokajíček, M.; Lo Vetere, M.; Rodriguez, F. Lucas; Macina, D.; Macrí, M.; Magazzù, C.; Magazzù, G.; Magri, A.; Maire, G.; Manco, A.; Meucci, M.; Minutoli, S.; Morelli, A.; Musico, P.; Negri, M.; Niewiadomski, H.; Noschis, E.; Notarnicola, G.; Oliveri, E.; Oljemark, F.; Orava, R.; Oriunno, M.; Perrot, A.-L.; Österberg, K.; Paoletti, R.; Pedreschi, E.; Petäjäjärvi, J.; Pollovio, P.; Quinto, M.; Radermacher, E.; Radicioni, E.; Rangod, S.; Ravotti, F.; Rella, G.; Robutti, E.; Ropelewski, L.; Ruggiero, G.; Rummel, A.; Saarikko, H.; Sanguinetti, G.; Santroni, A.; Scribano, A.; Sette, G.; Snoeys, W.; Spinella, F.; Squillacioti, P.; Ster, A.; Taylor, C.; Tazzioli, A.; Torazza, D.; Trovato, A.; Trummal, A.; Turini, N.; Vacek, V.; Van Remortel, N.; Vinš, V.; Watts, S.; Whitmore, J.; Wu, J.

2008-08-01

The TOTEM Experiment will measure the total pp cross-section with the luminosity-independent method and study elastic and diffractive scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, will be installed on each side in the pseudorapidity region 3.1 <= |η| <= 6.5, and Roman Pot stations will be placed at distances of ±147 m and ±220 m from IP5. Being an independent experiment but technically integrated into CMS, TOTEM will first operate in standalone mode to pursue its own physics programme and at a later stage together with CMS for a common physics programme. This article gives a description of the TOTEM apparatus and its performance.

On the Foundations of the Two Measures Field Theory

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

Guendelman, E. I.; Kaganovich, A. B.

2006-11-03

Two Measures Field Theory (TMT) uses both the Riemannian volume element {radical}(-g)d{sup 4}x and a new one Fcy d4x where the new measure of integration Fcy can be build of four scalar fields. Arguments in favor of TMT, both from the point of view of first principles and from the TMT results are summarized. Possible origin of the TMT and symmetries that protect the structure of TMT are reviewed. It appears that four measure scalar fields treated as 'physical coordinates' allow to define local observables in quantum gravity. The resolution of the old cosmological constant problem as a possible directmore » consequence of the TMT structure is discussed. Other applications of TMT to cosmology and particle physics are also mentioned.« less

Standard Model of Particle Physics--a health physics perspective.

PubMed

Bevelacqua, J J

2010-11-01

The Standard Model of Particle Physics is reviewed with an emphasis on its relationship to the physics supporting the health physics profession. Concepts important to health physics are emphasized and specific applications are presented. The capability of the Standard Model to provide health physics relevant information is illustrated with application of conservation laws to neutron and muon decay and in the calculation of the neutron mean lifetime.

``Magical'' fluid pathways: inspired airflow corridors for optimal drug delivery to human sinuses

NASA Astrophysics Data System (ADS)

Basu, Saikat; Farzal, Zainab; Kimbell, Julia S.

2017-11-01

Topical delivery methods like nasal sprays are an important therapeutic component for sinusitis (inflammation and clogging of the paranasal sinuses). The sinuses are air-filled sacs, identified as: maxillaries (under the eyes and deep to cheeks bilaterally; largest in volume), frontals (above and medial to the eyes, behind forehead area), ethmoids (between the eyes, inferior to the frontal sinuses), and sphenoids (superior and posterior to ethmoids). We develop anatomic CT-based 3D reconstructions of the human nasal cavity for multiple subjects. Through CFD simulations on Fluent for measured breathing rates, we track inspiratory airflow in all the models and the corresponding sprayed drug transport (for a commercially available sprayer, with experimentally tested particle size distributions). The protocol is implemented for a wide array of spray release points. We make the striking observation that the same release points in each subject provide better particle deposition in all the sinuses, despite the sinuses being located at different portions of the nasal cavity. This leads to the conjecture that the complicated anatomy-based flow physics artifacts in the nasal canal generate certain ``magical'' streamlines, providing passage for improved drug transport to all sinus targets. Supported by NIH Grant R01 HL122154.

Evidencing `Tight Bound States' in the Hydrogen Atom:. Empirical Manipulation of Large-Scale XD in Violation of QED

NASA Astrophysics Data System (ADS)

Amoroso, Richard L.; Vigier, Jean-Pierre

2013-09-01

In this work we extend Vigier's recent theory of `tight bound state' (TBS) physics and propose empirical protocols to test not only for their putative existence, but also that their existence if demonstrated provides the 1st empirical evidence of string theory because it occurs in the context of large-scale extra dimensionality (LSXD) cast in a unique M-Theoretic vacuum corresponding to the new Holographic Anthropic Multiverse (HAM) cosmological paradigm. Physicists generally consider spacetime as a stochastic foam containing a zero-point field (ZPF) from which virtual particles restricted by the quantum uncertainty principle (to the Planck time) wink in and out of existence. According to the extended de Broglie-Bohm-Vigier causal stochastic interpretation of quantum theory spacetime and the matter embedded within it is created annihilated and recreated as a virtual locus of reality with a continuous quantum evolution (de Broglie matter waves) governed by a pilot wave - a `super quantum potential' extended in HAM cosmology to be synonymous with the a `force of coherence' inherent in the Unified Field, UF. We consider this backcloth to be a covariant polarized vacuum of the (generally ignored by contemporary physicists) Dirac type. We discuss open questions of the physics of point particles (fermionic nilpotent singularities). We propose a new set of experiments to test for TBS in a Dirac covariant polarized vacuum LSXD hyperspace suggestive of a recently tested special case of the Lorentz Transformation put forth by Kowalski and Vigier. These protocols reach far beyond the recent battery of atomic spectral violations of QED performed through NIST.

Fermilab | Science at Fermilab | Experiments & Projects | Cosmic Frontier

Science.gov Websites

Proposed Projects and Experiments Fermilab's Tevatron Questions for the Universe Theory Computing High Answers Submit a Question Frontiers of Particle Physics Benefits to Society Benefits to Society Medicine Inquiring Minds Questions About Physics Other High-Energy Physics Sites More About Particle Physics Library

Advanced Level Physics Students' Conceptions of Quantum Physics.

ERIC Educational Resources Information Center

Mashhadi, Azam

This study addresses questions about particle physics that focus on the nature of electrons. Speculations as to whether they are more like particles or waves or like neither illustrate the difficulties with which students are confronted when trying to incorporate the concepts of quantum physics into their overall conceptual framework. Such…

Numerical investigation of liver radioembolization via computational particle-hemodynamics: The role of the microcatheter distal direction and microsphere injection point and velocity.

PubMed

Aramburu, Jorge; Antón, Raúl; Rivas, Alejandro; Ramos, Juan Carlos; Sangro, Bruno; Bilbao, José Ignacio

2016-11-07

Liver radioembolization is a treatment option for patients with primary and secondary liver cancer. The procedure consists of injecting radiation-emitting microspheres via an intra-arterially placed microcatheter, enabling the deposition of the microspheres in the tumoral bed. The microcatheter location and the particle injection rate are determined during a pretreatment work-up. The purpose of this study was to numerically study the effects of the injection characteristics during the first stage of microsphere travel through the bloodstream in a patient-specific hepatic artery (i.e., the near-tip particle-hemodynamics and the segment-to-segment particle distribution). Specifically, the influence of the distal direction of an end-hole microcatheter and particle injection point and velocity were analyzed. Results showed that the procedure targeted the right lobe when injecting from two of the three injection points under study and the remaining injection point primarily targeted the left lobe. Changes in microcatheter direction and injection velocity resulted in an absolute difference in exiting particle percentage for a given liver segment of up to 20% and 30%, respectively. It can be concluded that even though microcatheter placement is presumably reproduced in the treatment session relative to the pretreatment angiography, the treatment may result in undesired segment-to-segment particle distribution and therefore undesired treatment outcomes due to modifications of any of the parameters studied, i.e., microcatheter direction and particle injection point and velocity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Charge interaction between particle-laden fluid interfaces.

PubMed

Xu, Hui; Kirkwood, John; Lask, Mauricio; Fuller, Gerald

2010-03-02

Experiments are described where two oil/water interfaces laden with charged particles move at close proximity relative to one another. The particles on one of the interfaces were observed to be attracted toward the point of closest approach, forming a denser particle monolayer, while the particles on the opposite interface were repelled away from this point, forming a particle depletion zone. Such particle attraction/repulsion was observed even if one of the interfaces was free of particles. This phenomenon can be explained by the electrostatic interaction between the two interfaces, which causes surface charges (charged particles and ions) to redistribute in order to satisfy surface electric equipotential at each interface. In a forced particle oscillation experiment, we demonstrated the control of charged particle positions on the interface by manipulating charge interaction between interfaces.

Development of students' interest in particle physics as effect of participating in a Masterclass

NASA Astrophysics Data System (ADS)

Gedigk, Kerstin; Pospiech, Gesche

2016-05-01

The International Hands On Particle Physics Masterclasses are enjoying increasing popularity worldwide every year. In Germany a national program was brought to live in 2010, which offers these appreciated events to whole classes or courses of high school students all over the year. These events were evaluated concerning the issues of students' interest in particle physics and their perception of the events. How several interest variables interact with each other and the perception of the events is answered by structural equation modelling (sect. 5.2). The results give information about the events' effects on the students' interest development in particle physics, show which event features are important ( e.g. the authenticity) and give information about practical approaches to improve the effects of the Masterclasses. Section 5.3 deals with a group of participants which have a high interest in particle physics 6-8 weeks after the participation. The number of these students is remarkable large, with 26% of all participants. The investigation of this group shows that the Masterclass participation has the same positive effect on both sexes and all levels of physics education.

Matter, Energy, Space and Time: The International Linear Collider Physics Prospects and International Aspects

NASA Astrophysics Data System (ADS)

Wagner, Albrecht

2006-04-01

Over the past century, physicists have sought to explain the character of the matter and energy in our universe, to show how the basic forces of nature and the building blocks of matter come about, and to explore the fabric of space and time. In the past three decades, experiments at laboratories around the world have given us a precise confirmation of the underlying theory called the standard model. These particle physics advances have a direct impact for our understanding of the structure of the universe, both at its inception in the Big Bang, and in its evolution to the present and future. The final synthesis is not yet fully clear, but we know with confidence that major discoveries expanding the standard model framework will occur at the next generation of accelerators. The Large Hadron Collider (LHC) being built at CERN will take us into the discovery realm. The proposed International Linear Collider (ILC) will extend the discoveries and provide a wealth of precision measurements that are essential for giving deeper understanding of their meaning, and pointing the way to further evolution of particle physics in the future. A world-wide consensus has formed for a baseline ILC project at energies of 500 GeV and beyond. The choice of the superconducting technology as basis for the ILC has paved the way for a global design effort which has now taken full speed.

Physics and astrophysics from a lunar base; Proceedings of the 1st NASA Workshop, Stanford, CA, May 19, 20, 1989

NASA Technical Reports Server (NTRS)

Potter, A. E. (Editor); Wilson, T. L. (Editor)

1990-01-01

The present conference on physics and astrophysics from a lunar base encompasses space physics, cosmic ray physics, neutrino physics, experiments in gravitation and general relativity, gravitational radiation physics, cosmic background radiation, particle astrophysics, surface physics, and the physics of gamma rays and X-rays. Specific issues addressed include space-plasma physics research at a lunar base, prospects for neutral particle imaging, the atmosphere as particle detector, medium- and high-energy neutrino physics from a lunar base, muons on the moon, a search for relic supernovae antineutrinos, and the use of clocks in satellites orbiting the moon to test general relativity. Also addressed are large X-ray-detector arrays for physics experiments on the moon, and the measurement of proton decay, arcsec-source locations, halo dark matter and elemental abundances above 10 exp 15 eV at a lunar base.

PARTICLE PHYSICS: CERN Collider Glimpses Supersymmetry--Maybe.

PubMed

Seife, C

2000-07-14

Last week, particle physicists at the CERN laboratory in Switzerland announced that by smashing together matter and antimatter in four experiments, they detected an unexpected effect in the sprays of particles that ensued. The anomaly is subtle, and physicists caution that it might still be a statistical fluke. If confirmed, however, it could mark the long-sought discovery of a whole zoo of new particles--and the end of a long-standing model of particle physics.

Degenerate quantum gases with spin-orbit coupling: a review.

PubMed

Zhai, Hui

2015-02-01

This review focuses on recent developments in synthetic spin-orbit (SO) coupling in ultracold atomic gases. Two types of SO coupling are discussed. One is Raman process induced coupling between spin and motion along one of the spatial directions and the other is Rashba SO coupling. We emphasize their common features in both single-particle and two-body physics and the consequences of both in many-body physics. For instance, single particle ground state degeneracy leads to novel features of superfluidity and a richer phase diagram; increased low-energy density-of-state enhances interaction effects; the absence of Galilean invariance and spin-momentum locking gives rise to intriguing behaviours of superfluid critical velocity and novel quantum dynamics; and the mixing of two-body singlet and triplet states yields a novel fermion pairing structure and topological superfluids. With these examples, we show that investigating SO coupling in cold atom systems can, enrich our understanding of basic phenomena such as superfluidity, provide a good platform for simulating condensed matter states such as topological superfluids and more importantly, result in novel quantum systems such as SO coupled unitary Fermi gas and high spin quantum gases. Finally we also point out major challenges and some possible future directions.

A field study on the effects of dietary monensin on milk production and milk composition in dairy cows

PubMed Central

Dubuc, Jocelyn; DuTremblay, Denis; Baril, Jean; Bagg, Randy; Brodeur, Marcel; Duffield, Todd; DesCôteaux, Luc

2010-01-01

The objectives of this study were to quantify the effect of 16 ppm of dietary monensin on milk production and composition of dairy cows, and to investigate factors having a potential impact on this effect. Data were generated from a total of 3577 Holstein dairy cows (47 herds) in Quebec enrolled in a herd-level, randomized clinical trial investigating the effects of monensin supplementation. Milk production and composition data were collected from monthly dairy herd improvement (DHI) testing. Monensin increased milk production by 0.9 kg/cow/d in cows under 150 days in milk (DIM) (P < 0.05). Monensin decreased milk fat percentage by 0.18 percentage points during the whole lactation (P < 0.05). This decreasing effect was larger for component-fed cows (P < 0.05) and for cows being fed low levels of dietary physically effective particles (P < 0.05) when compared respectively to cows fed total mixed ration and cows fed high levels of dietary physically effective particles. The results of this study suggest that monensin influences milk production and milk composition of dairy cows, and that diet composition and feeding system influence those effects. PMID:20592825

Hydrodynamic lift of vesicles and red blood cells in flow--from Fåhræus & Lindqvist to microfluidic cell sorting.

PubMed

Geislinger, Thomas M; Franke, Thomas

2014-06-01

Hydrodynamic lift forces acting on cells and particles in fluid flow receive ongoing attention from medicine, mathematics, physics and engineering. The early findings of Fåhræus & Lindqvist on the viscosity change of blood with the diameter of capillaries motivated extensive studies both experimentally and theoretically to illuminate the underlying physics. We review this historical development that led to the discovery of the inertial and non-inertial lift forces and elucidate the origins of these forces that are still not entirely clear. Exploiting microfluidic techniques induced a tremendous amount of new insights especially into the more complex interactions between the flow field and deformable objects like vesicles or red blood cells. We trace the way from the investigation of single cell dynamics to the recent developments of microfluidic techniques for particle and cell sorting using hydrodynamic forces. Such continuous and label-free on-chip cell sorting devices promise to revolutionize medical analyses for personalized point-of-care diagnosis. We present the state-of-the-art of different hydrodynamic lift-based techniques and discuss their advantages and limitations. Copyright © 2014 Elsevier B.V. All rights reserved.

Recent Advances and Future Prospects in Fundamental Symmetries

NASA Astrophysics Data System (ADS)

Plaster, Brad

2017-09-01

A broad program of initiatives in fundamental symmetries seeks answers to several of the most pressing open questions in nuclear physics, ranging from the scale of the neutrino mass, to the particle-antiparticle nature of the neutrino, to the origin of the matter-antimatter asymmetry, to the limits of Standard Model interactions. Although the experimental program is quite broad, with efforts ranging from precision measurements of neutrino properties; to searches for electric dipole moments; to precision measurements of magnetic dipole moments; and to precision measurements of couplings, particle properties, and decays; all of these seemingly disparate initiatives are unified by several common threads. These include the use and exploitation of symmetry principles, novel cross-disciplinary experimental work at the forefront of the precision frontier, and the need for accompanying breakthroughs in development of the theory necessary for an interpretation of the anticipated results from these experiments. This talk will highlight recent accomplishments and advances in fundamental symmetries and point to the extraordinary level of ongoing activity aimed at realizing the development and interpretation of next-generation experiments. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-SC-0014622.

GPU surface extraction using the closest point embedding

NASA Astrophysics Data System (ADS)

Kim, Mark; Hansen, Charles

2015-01-01

Isosurface extraction is a fundamental technique used for both surface reconstruction and mesh generation. One method to extract well-formed isosurfaces is a particle system; unfortunately, particle systems can be slow. In this paper, we introduce an enhanced parallel particle system that uses the closest point embedding as the surface representation to speedup the particle system for isosurface extraction. The closest point embedding is used in the Closest Point Method (CPM), a technique that uses a standard three dimensional numerical PDE solver on two dimensional embedded surfaces. To fully take advantage of the closest point embedding, it is coupled with a Barnes-Hut tree code on the GPU. This new technique produces well-formed, conformal unstructured triangular and tetrahedral meshes from labeled multi-material volume datasets. Further, this new parallel implementation of the particle system is faster than any known methods for conformal multi-material mesh extraction. The resulting speed-ups gained in this implementation can reduce the time from labeled data to mesh from hours to minutes and benefits users, such as bioengineers, who employ triangular and tetrahedral meshes

Theoretical analysis of the influence of aerosol size distribution and physical activity on particle deposition pattern in human lungs.

PubMed

Voutilainen, Arto; Kaipio, Jari P; Pekkanen, Juha; Timonen, Kirsi L; Ruuskanen, Juhani

2004-01-01

A theoretical comparison of modeled particle depositions in the human respiratory tract was performed by taking into account different particle number and mass size distributions and physical activity in an urban environment. Urban-air data on particulate concentrations in the size range 10 nm-10 microm were used to estimate the hourly average particle number and mass size distribution functions. The functions were then combined with the deposition probability functions obtained from a computerized ICRP 66 deposition model of the International Commission on Radiological Protection to calculate the numbers and masses of particles deposited in five regions of the respiratory tract of a male adult. The man's physical activity and minute ventilation during the day were taken into account in the calculations. Two different mass and number size distributions of aerosol particles with equal (computed) <10 microm particle mass concentrations gave clearly different deposition patterns in the central and peripheral regions of the human respiratory tract. The deposited particle numbers and masses were much higher during the day (0700-1900) than during the night (1900-0700) because an increase in physical activity and ventilation were temporally associated with highly increased traffic-derived particles in urban outdoor air. In future analyses of the short-term associations between particulate air pollution and health, it would not only be important to take into account the outdoor-to-indoor penetration of different particle sizes and human time-activity patterns, but also actual lung deposition patterns and physical activity in significant microenvironments.

Press Room

Science.gov Websites

Science at Fermilab Fermilab and the Higgs Boson Frontiers of Particle Physics Experiments & Projects Frontiers of Particle Physics Benefits to Society Contacting Fermilab General Contact Information Email -12 Programs Lederman Science Center Saturday Morning Physics Cooperative Education Program

Silicone-containing aqueous polymer dispersions with hybrid particle structure.

PubMed

Kozakiewicz, Janusz; Ofat, Izabela; Trzaskowska, Joanna

2015-09-01

In this paper the synthesis, characterization and application of silicone-containing aqueous polymer dispersions (APD) with hybrid particle structure are reviewed based on available literature data. Advantages of synthesis of dispersions with hybrid particle structure over blending of individual dispersions are pointed out. Three main processes leading to silicone-containing hybrid APD are identified and described in detail: (1) emulsion polymerization of organic unsaturated monomers in aqueous dispersions of silicone polymers or copolymers, (2) emulsion copolymerization of unsaturated organic monomers with alkoxysilanes or polysiloxanes with unsaturated functionality and (3) emulsion polymerization of alkoxysilanes (in particular with unsaturated functionality) and/or cyclic siloxanes in organic polymer dispersions. The effect of various factors on the properties of such hybrid APD and films as well as on hybrid particles composition and morphology is presented. It is shown that core-shell morphology where silicones constitute either the core or the shell is predominant in hybrid particles. Main applications of silicone-containing hybrid APD and related hybrid particles are reviewed including (1) coatings which show specific surface properties such as enhanced water repellency or antisoiling or antigraffiti properties due to migration of silicone to the surface, and (2) impact modifiers for thermoplastics and thermosets. Other processes in which silicone-containing particles with hybrid structure can be obtained (miniemulsion polymerization, polymerization in non-aqueous media, hybridization of organic polymer and polysiloxane, emulsion polymerization of silicone monomers in silicone polymer dispersions and physical methods) are also discussed. Prospects for further developments in the area of silicone-containing hybrid APD and related hybrid particles are presented. Copyright © 2015. Published by Elsevier B.V.

U.C. Davis high energy particle physics research: Technical progress report -- 1990

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

NONE

Summaries of progress made for this period is given for each of the following areas: (1) Task A--Experiment, H1 detector at DESY; (2) Task C--Experiment, AMY detector at KEK; (3) Task D--Experiment, fixed target detectors at Fermilab; (4) Task F--Experiment, PEP detector at SLAC and pixel detector; (5) Task B--Theory, particle physics; and (6) Task E--Theory, particle physics.

A facility to search for hidden particles at the CERN SPS: the SHiP physics case.

PubMed

Alekhin, Sergey; Altmannshofer, Wolfgang; Asaka, Takehiko; Batell, Brian; Bezrukov, Fedor; Bondarenko, Kyrylo; Boyarsky, Alexey; Choi, Ki-Young; Corral, Cristóbal; Craig, Nathaniel; Curtin, David; Davidson, Sacha; de Gouvêa, André; Dell'Oro, Stefano; deNiverville, Patrick; Bhupal Dev, P S; Dreiner, Herbi; Drewes, Marco; Eijima, Shintaro; Essig, Rouven; Fradette, Anthony; Garbrecht, Björn; Gavela, Belen; Giudice, Gian F; Goodsell, Mark D; Gorbunov, Dmitry; Gori, Stefania; Grojean, Christophe; Guffanti, Alberto; Hambye, Thomas; Hansen, Steen H; Helo, Juan Carlos; Hernandez, Pilar; Ibarra, Alejandro; Ivashko, Artem; Izaguirre, Eder; Jaeckel, Joerg; Jeong, Yu Seon; Kahlhoefer, Felix; Kahn, Yonatan; Katz, Andrey; Kim, Choong Sun; Kovalenko, Sergey; Krnjaic, Gordan; Lyubovitskij, Valery E; Marcocci, Simone; Mccullough, Matthew; McKeen, David; Mitselmakher, Guenakh; Moch, Sven-Olaf; Mohapatra, Rabindra N; Morrissey, David E; Ovchynnikov, Maksym; Paschos, Emmanuel; Pilaftsis, Apostolos; Pospelov, Maxim; Reno, Mary Hall; Ringwald, Andreas; Ritz, Adam; Roszkowski, Leszek; Rubakov, Valery; Ruchayskiy, Oleg; Schienbein, Ingo; Schmeier, Daniel; Schmidt-Hoberg, Kai; Schwaller, Pedro; Senjanovic, Goran; Seto, Osamu; Shaposhnikov, Mikhail; Shchutska, Lesya; Shelton, Jessie; Shrock, Robert; Shuve, Brian; Spannowsky, Michael; Spray, Andy; Staub, Florian; Stolarski, Daniel; Strassler, Matt; Tello, Vladimir; Tramontano, Francesco; Tripathi, Anurag; Tulin, Sean; Vissani, Francesco; Winkler, Martin W; Zurek, Kathryn M

2016-12-01

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, [Formula: see text] and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals-scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

Theoretical Studies of Alfven Waves and Energetic Particle Physics in Fusion Plasmas

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

Chen, Liu

This report summarizes major theoretical findings in the linear as well as nonlinear physics of Alfvén waves and energetic particles in magnetically confined fusion plasmas. On the linear physics, a variational formulation, based on the separation of singular and regular spatial scales, for drift-Alfvén instabilities excited by energetic particles is established. This variational formulation is then applied to derive the general fishbone-like dispersion relations corresponding to the various Alfvén eigenmodes and energetic-particle modes. It is further employed to explore in depth the low-frequency Alfvén eigenmodes and demonstrate the non-perturbative nature of the energetic particles. On the nonlinear physics, new novelmore » findings are obtained on both the nonlinear wave-wave interactions and nonlinear wave-energetic particle interactions. It is demonstrated that both the energetic particles and the fine radial mode structures could qualitatively affect the nonlinear evolution of Alfvén eigenmodes. Meanwhile, a theoretical approach based on the Dyson equation is developed to treat self-consistently the nonlinear interactions between Alfvén waves and energetic particles, and is then applied to explain simulation results of energetic-particle modes. Relevant list of journal publications on the above findings is also included.« less

Particle physics for primary schools—enthusing future physicists

NASA Astrophysics Data System (ADS)

Pavlidou, M.; Lazzeroni, C.

2016-09-01

In recent years, the realisation that children make decisions and choices about subjects they like in primary school, became widely understood. For this reason academic establishments focus some of their public engagement activities towards the younger ages. Taking advantage of Professor Lazzeroni’s long-standing experience in particle physics research, during the last academic year we designed and trialled a particle physics workshop for primary schools. The workshop allows young children (ages 8-11) to learn the world of fundamental particles, use creative design to make particle models. The workshop has already been trialled in many primary schools, receiving very positive evaluation. The initial resources were reviewed and improved, based on the feedback received from school teachers and communicators.

Spallation reactions: A successful interplay between modeling and applications

NASA Astrophysics Data System (ADS)

David, J.-C.

2015-06-01

The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200MeV deuterons and 400MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. In the same year, R. Serber described the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a workshop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.

Martinus Veltman, the Electroweak Theory, and Elementary Particle Physics

Science.gov Websites

Particle Physics Resources with Additional Information Martinus Veltman Courtesy University of Michigan Martinus J.G. Veltman, the John D. MacArthur Professor Emeritus of Physics at the University of Michigan , was awarded the 1999 Nobel Prize in physics "for elucidating the quantum structure of electroweak

Field-Lines-Threaded Model for: (1) the Low Solar Corona; (2) Electrons in the Transition Region; and (3) Solar Energetic Particle Acceleration and Transport

NASA Astrophysics Data System (ADS)

Sokolov, I.; van der Holst, B.; Jin, M.; Gombosi, T. I.; Taktakishvili, A.; Khazanov, G. V.

2013-12-01

In numerical simulations of the solar corona, both for the ambient state and especially for dynamical processes the most computational resources are spent for maintaining the numerical solution in the Low Solar Corona and in the transition region, where the temperature gradients are very sharp and the magnetic field has a complicated topology. The degraded computational efficiency is caused by the need in a highest resolution as well as the use of the fully three-dimensional implicit solver for electron heat conduction. On the other hand, the physical nature of the processes involved is rather simple (which still does not facilitate the numerical methods) as long as the heat fluxes as well as slow plasma motional velocities are aligned with the magnetic field. The Alfven wave turbulence, which is often believed to be the main driver of the solar wind and the main source of the coronal heating, is characterized by the Poynting flux of the waves, which is also aligned with the magnetic field. Therefore, the plasma state in any point of the three-dimensional grid in the Low Solar Corona can be found by solving a set of one-dimensional equations for the magnetic field line ('thread'), which passes through this point and connects it to the chromosphere and to the global Solar Corona. In the present paper we describe an innovative computational technology based upon the use of the magnetic-field-line-threads to find the local solution. We present the development of the AWSoM code of the University of Michigan with the field-lines-threaded Low Solar Corona. In the transition region, where the essentially kinetic description of the electron energy fluxes is required, we solve the Fokker-Plank equation on the system of threads, to achieve the physically consistent description of chromosphere evaporation. The third application for the field-lines-treaded model is the Solar Energetic Particle (SEP) acceleration and transport. Being the natural extension of the Field-Line-Advection Model for Particle Acceleration (FLAMPA), earlier suggested for a single magnetic field line advected with the plasma motion, the multiple-field-lines model allows us to simulate the SEP fluxes at multiple points of possible observation (at the Earth location, at STEREOs, at Mercury).

Lagrangian particles with mixing. I. Simulating scalar transport

NASA Astrophysics Data System (ADS)

Klimenko, A. Y.

2009-06-01

The physical similarity and mathematical equivalence of continuous diffusion and particle random walk forms one of the cornerstones of modern physics and the theory of stochastic processes. The randomly walking particles do not need to posses any properties other than location in physical space. However, particles used in many models dealing with simulating turbulent transport and turbulent combustion do posses a set of scalar properties and mixing between particle properties is performed to reflect the dissipative nature of the diffusion processes. We show that the continuous scalar transport and diffusion can be accurately specified by means of localized mixing between randomly walking Lagrangian particles with scalar properties and assess errors associated with this scheme. Particles with scalar properties and localized mixing represent an alternative formulation for the process, which is selected to represent the continuous diffusion. Simulating diffusion by Lagrangian particles with mixing involves three main competing requirements: minimizing stochastic uncertainty, minimizing bias introduced by numerical diffusion, and preserving independence of particles. These requirements are analyzed for two limited cases of mixing between two particles and mixing between a large number of particles. The problem of possible dependences between particles is most complicated. This problem is analyzed using a coupled chain of equations that has similarities with Bogolubov-Born-Green-Kirkwood-Yvon chain in statistical physics. Dependences between particles can be significant in close proximity of the particles resulting in a reduced rate of mixing. This work develops further ideas introduced in the previously published letter [Phys. Fluids 19, 031702 (2007)]. Paper I of this work is followed by Paper II [Phys. Fluids 19, 065102 (2009)] where modeling of turbulent reacting flows by Lagrangian particles with localized mixing is specifically considered.

Pions to Quarks

NASA Astrophysics Data System (ADS)

Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian

2009-01-01

Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the neutrino Frederick Reines; 25. Recollections on the establishment of the weak-interaction notion Bruno M. Pontecorvo; 26. Symmetry and conservation laws in particle physics in the fifties Louis Michel; 27. A connection between the strong and weak interactions Sam B. Treiman; Part VII. Weak interactions and parity nonconservation; 29. The nondiscovery of parity nonconservation Allan Franklin; 30. K-meson decays and parity violation Richard H. Dalitz; 31. An Experimentalist's Perspective Val L. Fitch; 32. The early experiments leading to the V - A interaction Valentine L. Telegdi; 33. Midcentury adventures in particles physics E. C. G. Sudarshan; Part VIII. The particle physics community; 34. The postwar political economy of high-energy physics Robert Seidel; 35. The history of CERN during the early 1950s Edoardo Amaldi; 36. Arguments pro and contra the European laboratory in the participating countries Armin Hermann; 37. Physics and excellences of the life it brings Abdus Salam; 38. Social aspects of Japanese particle physics in the 1950s Michiji Konuma; Part IX. Theories of hadrons; 39. The early S-matrix theory and its propagation (1942-1952) Helmut Rechenberg; 40. From field theory to phenomenology: the history of dispersion relations Andy Pickering; 41. Particles as S-matrix poles: hadron democracy Geoffrey F. Chew; 42. The general theory of quantised fields in the 1950s Arthur S. Wrightman; 43. The classification and structure of hadrons Yuval Ne'eman; 44. Gauge principle, vector-meson dominance and spontaneous symmetry breaking Yoichiro Nambu; Part X. Personal overviews; 45. Scientific impact of the first decade of the Rochester conferences (1950-1960) Robert E. Marshak; 46. Some reflections on the history of particle physics in the 1950s Silvan S. Schweber; 47. Progress in elementary particle theory 1950-1964 Murray Gell-Mann.

Manipulation of particles by weak forces

NASA Technical Reports Server (NTRS)

Adler, M. S.; Savkar, S. D.; Summerhayes, H. R.

1972-01-01

Quantitative relations between various force fields and their effects on the motion of particles of various sizes and physical characteristics were studied. The forces considered were those derived from light, heat, microwaves, electric interactions, magnetic interactions, particulate interactions, and sound. A physical understanding is given of the forces considered as well as formulae which express how the size of the force depends on the physical and electrical properties of the particle. The drift velocity in a viscous fluid is evaluated as a function of initial acceleration and the effects of thermal random motion are considered. A means of selectively sorting or moving particles by choosing a force system and/or environment such that the particle of interest reacts uniquely was developed. The forces considered and a demonstration of how the initial acceleration, drift velocity, and ultimate particle density distribution is affected by particle, input, and environmental parameters are tabulated.

Quarks, Leptons, and Bosons: A Particle Physics Primer.

ERIC Educational Resources Information Center

Wagoner, Robert; Goldsmith, Donald

1983-01-01

Presented is a non-technical introduction to particle physics. The material is adapted from chapter 3 of "Cosmic Horizons," (by Robert Wagoner and Don Goldsmith), a lay-person's introduction to cosmology. Among the topics considered are elementary particles, forces and motion, and higher level structures. (JN)

Higgs Particle: The Origin of Mass

NASA Astrophysics Data System (ADS)

Okada, Yasuhiro

2007-11-01

The Higgs particle is a new elementary particle predicted in the Standard Model of the elementary particle physics. It plays a special role in the theory of mass generation of quarks, leptons, and gauge bosons. In this article, theoretical issues on the Higgs mechanism are first discussed, and then experimental prospects on the Higgs particle study at the future collider experiments, LHC and ILC, are reviewed. The Higgs coupling determination is an essential step to establish the mass generation mechanism, which could lead to a deeper understanding of particle physics.

Charge Transport Phenomena in Detectors of the Cryogenic Dark Matter Search

NASA Astrophysics Data System (ADS)

Sundqvist, Kyle

2008-03-01

The Cryogenic Dark Matter Search (CDMS) seeks to detect putative weakly-interacting massive particles (WIMPS), which could explain the dark matter problem in cosmology and particle physics. By simultaneously measuring the number of charge carriers and the energy in athermal phonons created by particle interactions in intrinsic Ge and Si crystals at a temperature of 40 mK, a signature response for each event is produced. This response, combined with phonon pulse-shape information, allows CDMS to actively discriminate candidate WIMP interactions with nuclei apart from electromagnetic radioactive background which interacts with electrons. The challenges associated with these techniques are unique. Carrier drift-fields are maintained at only a few V/cm, else drift-emitted Luke-Neganov phonons would dominate the phonons of the original interaction. Under such conditions, carrier scattering is dominated by zero-point fluctuations of the lattice ions. It has been an open question how well the 8 Kelvin data prominent in the literature depicts this case. We compare the simulated transport properties of electrons and holes in <100> Ge at 40 mK and at 8 K, and apply this understanding to our detectors.

The formation of massive molecular filaments and massive stars triggered by a magnetohydrodynamic shock wave

NASA Astrophysics Data System (ADS)

Inoue, Tsuyoshi; Hennebelle, Patrick; Fukui, Yasuo; Matsumoto, Tomoaki; Iwasaki, Kazunari; Inutsuka, Shu-ichiro

2018-05-01

Recent observations suggest an that intensive molecular cloud collision can trigger massive star/cluster formation. The most important physical process caused by the collision is a shock compression. In this paper, the influence of a shock wave on the evolution of a molecular cloud is studied numerically by using isothermal magnetohydrodynamics simulations with the effect of self-gravity. Adaptive mesh refinement and sink particle techniques are used to follow the long-time evolution of the shocked cloud. We find that the shock compression of a turbulent inhomogeneous molecular cloud creates massive filaments, which lie perpendicularly to the background magnetic field, as we have pointed out in a previous paper. The massive filament shows global collapse along the filament, which feeds a sink particle located at the collapse center. We observe a high accretion rate \\dot{M}_acc> 10^{-4} M_{⊙}yr-1 that is high enough to allow the formation of even O-type stars. The most massive sink particle achieves M > 50 M_{⊙} in a few times 105 yr after the onset of the filament collapse.

Transitions between homogeneous phases of polar active liquids

NASA Astrophysics Data System (ADS)

Dauchot, Olivier; Nguyen Thu Lam, Khanh Dang; Schindler, Michael; EC2M Team; PCT Team

2015-03-01

Polar active liquids, composed of aligning self-propelled particle exhibit large scale collective motion. Simulations of Vicsek-like models of constant-speed point particles, aligning with their neighbors in the presence of noise, have revealed the existence of a transition towards a true long range order polar-motion phase. Generically, the homogenous polar state is unstable; non-linear propagative structures develop; and the transition is discontinuous. The long range dynamics of these systems has been successfully captured using various scheme of kinetic theories. However the complexity of the dynamics close to the transition has somewhat hindered more basics questions. Is there a simple way to predict the existence and the order of a transition to collective motion for a given microscopic dynamics? What would be the physically meaningful and relevant quantity to answer this question? Here, we tackle these questions, restricting ourselves to the study of the homogeneous phases of polar active liquids in the low density limit and obtain a very intuitive understanding of the conditions which particle interaction must satisfy to induce a transition towards collective motion.

The Evolution of Universe as Splitting of the ``Non Existing'' and Space-Time Expansion

NASA Astrophysics Data System (ADS)

Nassikas, A. A.

2010-09-01

The purpose of this paper is to show that the creation of Universe can be regarded as a splitting process of the ``non existing'', ``where'' there is no space-time and that the expansion of Universe is due to the compatibility between the stochastic-quantum space-time created and the surrounding ``non existing''. In this way it is not required that space time should pre-exist in contrast, as it can be shown, to the Universe creation from vacuum theory. The present point of view can be derived on the basis of a Minimum Contradictions Physics according to which stochastic-quantum space-time is matter itself; there are (g)-mass and (em)-charge space-time which interact-communicate through photons [(g) or (em) particles with zero rest mass]. This point of view is compatible to the present knowledge of CERN and Fermi Lab experiments as well as to the neutron synthesis according to Rutherford, experimentally verified and theoretically explained through Hadronic Mechanics by R. M. Santilli. On the basis of the Minimum Contradictions Physics a quantum gravity formula is derived which implies either positive or negative gravitational acceleration; thus, bodies can be attracted while Universe can be expanded. Minimum Contradictions Physics, under certain simplifications, is compatible to Newton Mechanics, Relativity Theory and QM. This physics is compatible to language through which it is stated. On this basis the physical laws are the principles of language i.e.: the Classical Logic, the Sufficient Reason Principle the Communication Anterior-Posterior Axiom and the Claim for Minimum Contradictions; according to a theorem contradictions cannot be vanished.

An electrostatic Particle-In-Cell code on multi-block structured meshes

NASA Astrophysics Data System (ADS)

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca; Vernon, Louis J.; Moulton, J. David

2017-12-01

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. Despite the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where an arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma-material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. Compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.

An electrostatic Particle-In-Cell code on multi-block structured meshes

DOE PAGES

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca; ...

2017-09-14

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. In spite of the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where anmore » arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma–material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. And compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.« less

Variability in Bioreactivity Linked to Changes in Size and Zeta Potential of Diesel Exhaust Particles in Human Immune Cells

PubMed Central

Sarkar, Srijata; Zhang, Lin; Subramaniam, Prasad; Lee, Ki-Bum; Garfunkel, Eric; Strickland, Pamela A. Ohman.; Mainelis, Gediminas; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Ryan, Mary; Porter, Alex; Schwander, Stephan

2014-01-01

Acting as fuel combustion catalysts to increase fuel economy, cerium dioxide (ceria, CeO2) nanoparticles have been used in Europe as diesel fuel additives (Envirox™). We attempted to examine the effects of particles emitted from a diesel engine burning either diesel (diesel exhaust particles, DEP) or diesel doped with various concentrations of CeO2 (DEP-Env) on innate immune responses in THP-1 and primary human peripheral blood mononuclear cells (PBMC). Batches of DEP and DEP-Env were obtained on three separate occasions using identical collection and extraction protocols with the aim of determining the reproducibility of particles generated at different times. However, we observed significant differences in size and surface charge (zeta potential) of the DEP and DEP-Env across the three batches. We also observed that exposure of THP-1 cells and PBMC to identical concentrations of DEP and DEP-Env from the three batches resulted in statistically significant differences in bioreactivity as determined by IL-1β, TNF-α, IL-6, IFN-γ, and IL-12p40 mRNA (by qRT-PCR) and protein expression (by ELISPOT assays). Importantly, bioreactivity was noted in very tight ranges of DEP size (60 to 120 nm) and zeta potential (−37 to −41 mV). Thus, these physical properties of DEP and DEP-Env were found to be the primary determinants of the bioreactivity measured in this study. Our findings also point to the potential risk of over- or under- estimation of expected bioreactivity effects (and by inference of public health risks) from bulk DEP use without taking into account potential batch-to-batch variations in physical (and possibly chemical) properties. PMID:24825358

Characterization and Physical Explanation of Energetic Particles on Planck HFI Instrument

NASA Astrophysics Data System (ADS)

Catalano, A.; Ade, P.; Atik, Y.; Benoit, A.; Bréele, E.; Bock, J. J.; Camus, P.; Charra, M.; Crill, B. P.; Coron, N.; Coulais, A.; Désert, F.-X.; Fauvet, L.; Giraud-Héraud, Y.; Guillaudin, O.; Holmes, W.; Jones, W. C.; Lamarre, J.-M.; Macías-Pérez, J.; Martinez, M.; Miniussi, A.; Monfardini, A.; Pajot, F.; Patanchon, G.; Pelissier, A.; Piat, M.; Puget, J.-L.; Renault, C.; Rosset, C.; Santos, D.; Sauvé, A.; Spencer, L.; Sudiwala, R.

2014-09-01

The Planck High Frequency Instrument (HFI) has been surveying the sky continuously from the second Lagrangian point (L2) between August 2009 and January 2012. It operates with 52 high impedance bolometers cooled at 100 mK in a range of frequency between 100 GHz and 1 THz with unprecedented sensitivity, but strong coupling with cosmic radiation. At L2, the particle flux is about 5 and is dominated by protons incident on the spacecraft. Protons with an energy above 40 MeV can penetrate the focal plane unit box causing two different effects: glitches in the raw data from direct interaction of cosmic rays with detectors (producing a data loss of about 15 % at the end of the mission) and thermal drifts in the bolometer plate at 100 mK adding non-Gaussian noise at frequencies below 0.1 Hz. The HFI consortium has made strong efforts in order to correct for this effect on the time ordered data and final Planck maps. This work intends to give a view of the physical explanation of the glitches observed in the HFI instrument in-flight. To reach this goal, we performed several ground-based experiments using protons and particles to test the impact of particles on the HFI spare bolometers with a better control of the environmental conditions with respect to the in-flight data. We have shown that the dominant part of glitches observed in the data comes from the impact of cosmic rays in the silicon die frame supporting the micro-machined bolometric detectors propagating energy mainly by ballistic phonons and by thermal diffusion. The implications of these results for future satellite missions will be discussed.

An electrostatic Particle-In-Cell code on multi-block structured meshes

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

Meierbachtol, Collin S.; Svyatskiy, Daniil; Delzanno, Gian Luca

We present an electrostatic Particle-In-Cell (PIC) code on multi-block, locally structured, curvilinear meshes called Curvilinear PIC (CPIC). Multi-block meshes are essential to capture complex geometries accurately and with good mesh quality, something that would not be possible with single-block structured meshes that are often used in PIC and for which CPIC was initially developed. In spite of the structured nature of the individual blocks, multi-block meshes resemble unstructured meshes in a global sense and introduce several new challenges, such as the presence of discontinuities in the mesh properties and coordinate orientation changes across adjacent blocks, and polyjunction points where anmore » arbitrary number of blocks meet. In CPIC, these challenges have been met by an approach that features: (1) a curvilinear formulation of the PIC method: each mesh block is mapped from the physical space, where the mesh is curvilinear and arbitrarily distorted, to the logical space, where the mesh is uniform and Cartesian on the unit cube; (2) a mimetic discretization of Poisson's equation suitable for multi-block meshes; and (3) a hybrid (logical-space position/physical-space velocity), asynchronous particle mover that mitigates the performance degradation created by the necessity to track particles as they move across blocks. The numerical accuracy of CPIC was verified using two standard plasma–material interaction tests, which demonstrate good agreement with the corresponding analytic solutions. And compared to PIC codes on unstructured meshes, which have also been used for their flexibility in handling complex geometries but whose performance suffers from issues associated with data locality and indirect data access patterns, PIC codes on multi-block structured meshes may offer the best compromise for capturing complex geometries while also maintaining solution accuracy and computational efficiency.« less

Spin-orbit induced electronic spin separation in semiconductor nanostructures.

PubMed

Kohda, Makoto; Nakamura, Shuji; Nishihara, Yoshitaka; Kobayashi, Kensuke; Ono, Teruo; Ohe, Jun-ichiro; Tokura, Yasuhiro; Mineno, Taiki; Nitta, Junsaku

2012-01-01

The demonstration of quantized spin splitting by Stern and Gerlach is one of the most important experiments in modern physics. Their discovery was the precursor of recent developments in spin-based technologies. Although electrical spin separation of charged particles is fundamental in spintronics, in non-uniform magnetic fields it has been difficult to separate the spin states of charged particles due to the Lorentz force, as well as to the insufficient and uncontrollable field gradients. Here we demonstrate electronic spin separation in a semiconductor nanostructure. To avoid the Lorentz force, which is inevitably induced when an external magnetic field is applied, we utilized the effective non-uniform magnetic field which originates from the Rashba spin-orbit interaction in an InGaAs-based heterostructure. Using a Stern-Gerlach-inspired mechanism, together with a quantum point contact, we obtained field gradients of 10(8) T m(-1) resulting in a highly polarized spin current.

Spin–orbit induced electronic spin separation in semiconductor nanostructures

PubMed Central

Kohda, Makoto; Nakamura, Shuji; Nishihara, Yoshitaka; Kobayashi, Kensuke; Ono, Teruo; Ohe, Jun-ichiro; Tokura, Yasuhiro; Mineno, Taiki; Nitta, Junsaku

2012-01-01

The demonstration of quantized spin splitting by Stern and Gerlach is one of the most important experiments in modern physics. Their discovery was the precursor of recent developments in spin-based technologies. Although electrical spin separation of charged particles is fundamental in spintronics, in non-uniform magnetic fields it has been difficult to separate the spin states of charged particles due to the Lorentz force, as well as to the insufficient and uncontrollable field gradients. Here we demonstrate electronic spin separation in a semiconductor nanostructure. To avoid the Lorentz force, which is inevitably induced when an external magnetic field is applied, we utilized the effective non-uniform magnetic field which originates from the Rashba spin–orbit interaction in an InGaAs-based heterostructure. Using a Stern–Gerlach-inspired mechanism, together with a quantum point contact, we obtained field gradients of 108 T m−1 resulting in a highly polarized spin current. PMID:23011136

Probing the quantum vacuum with petawatt lasers

NASA Astrophysics Data System (ADS)

Hill, W. T., III; Roso, L.

2017-07-01

Due to the bosonic nature of the photon, increasing the peak intensity through a combination of raising the pulse energy and decreasing the pulse duration will pile up more and more photons within the same finite region of space. In the absence of material, this continues until the vacuum is stressed to the point of breakdown and virtual particles become real. The critical intensity where this occurs for electrons and positrons - the so-called Schwinger limit - is predicted to be ˜ 1029 W/cm2. At substantially lower intensities, however, nonlinear aspects of the quantum vacuum associated with polarization of the vacuum can be explored. These studies become viable at the petawatt level where 1023 W/cm2 and above can be reached. This is an era into which we are just embarking that will provide critical tests of QED and theories beyond the Standard Model of particle physics.

Granular Mechanics and Surface Systems Lab

NASA Technical Reports Server (NTRS)

Randle, Leah

2007-01-01

The cratering of sand under gas jets is observed to further understanding of soil in hopes to further understand lunar soil. Lunar soil is important to understand because it is causing problems with the materials taken into space including the shuttle. Lunar soil is not rounded like beach sand. Lunar soil is sharp like little particles of glass, and some times when blown they can hook on to one another and become bigger particles. The experiments are designed to help to understand some of the basic physics in how the shuttle jets will interact with lunar soil and how to control the lunar soil. These experiments investigate the diameter of the gas jet and the size of the sand grains to determine how these parameters affect the erosion rate and the cratering processes. Therefore, the experiments preformed will point out what is dependent and what is independent.

Consistency of multi-time Dirac equations with general interaction potentials

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

Deckert, Dirk-André, E-mail: deckert@math.lmu.de; Nickel, Lukas, E-mail: nickel@math.lmu.de

In 1932, Dirac proposed a formulation in terms of multi-time wave functions as candidate for relativistic many-particle quantum mechanics. A well-known consistency condition that is necessary for existence of solutions strongly restricts the possible interaction types between the particles. It was conjectured by Petrat and Tumulka that interactions described by multiplication operators are generally excluded by this condition, and they gave a proof of this claim for potentials without spin-coupling. Under suitable assumptions on the differentiability of possible solutions, we show that there are potentials which are admissible, give an explicit example, however, show that none of them fulfills themore » physically desirable Poincaré invariance. We conclude that in this sense, Dirac’s multi-time formalism does not allow to model interaction by multiplication operators, and briefly point out several promising approaches to interacting models one can instead pursue.« less

Assembly of the most topologically regular two-dimensional micro and nanocrystals with spherical, conical, and tubular shapes

NASA Astrophysics Data System (ADS)

Roshal, D. S.; Konevtsova, O. V.; Myasnikova, A. E.; Rochal, S. B.

2016-11-01

We consider how to control the extension of curvature-induced defects in the hexagonal order covering different curved surfaces. In these frames we propose a physical mechanism for improving structures of two-dimensional spherical colloidal crystals (SCCs). For any SCC comprising of about 300 or less particles the mechanism transforms all extended topological defects (ETDs) in the hexagonal order into the point disclinations. Perfecting the structure is carried out by successive cycles of the particle implantation and subsequent relaxation of the crystal. The mechanism is potentially suitable for obtaining colloidosomes with better selective permeability. Our approach enables modeling the most topologically regular tubular and conical two-dimensional nanocrystals including various possible polymorphic forms of the HIV viral capsid. Different HIV-like shells with an arbitrary number of structural units (SUs) and desired geometrical parameters are easily formed. Faceting of the obtained structures is performed by minimizing the suggested elastic energy.

Topological Classification of Crystalline Insulators through Band Structure Combinatorics

NASA Astrophysics Data System (ADS)

Kruthoff, Jorrit; de Boer, Jan; van Wezel, Jasper; Kane, Charles L.; Slager, Robert-Jan

2017-10-01

We present a method for efficiently enumerating all allowed, topologically distinct, electronic band structures within a given crystal structure in all physically relevant dimensions. The algorithm applies to crystals without time-reversal, particle-hole, chiral, or any other anticommuting or anti-unitary symmetries. The results presented match the mathematical structure underlying the topological classification of these crystals in terms of K -theory and therefore elucidate this abstract mathematical framework from a simple combinatorial perspective. Using a straightforward counting procedure, we classify all allowed topological phases of spinless particles in crystals in class A . Employing this classification, we study transitions between topological phases within class A that are driven by band inversions at high-symmetry points in the first Brillouin zone. This enables us to list all possible types of phase transitions within a given crystal structure and to identify whether or not they give rise to intermediate Weyl semimetallic phases.

Frictional lubricity enhanced by quantum mechanics.

PubMed

Zanca, Tommaso; Pellegrini, Franco; Santoro, Giuseppe E; Tosatti, Erio

2018-04-03

The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in an important manner the frictional dissipation of a light particle forced to slide in an optical lattice. The density matrix-calculated evolution of the quantum version of the basic Prandtl-Tomlinson model, describing the dragging by an external force of a point particle in a periodic potential, shows that purely classical friction predictions can be very wrong. The strongest quantum effect occurs not for weak but for strong periodic potentials, where barriers are high but energy levels in each well are discrete, and resonant Rabi or Landau-Zener tunneling to states in the nearest well can preempt classical stick-slip with nonnegligible efficiency, depending on the forcing speed. The resulting permeation of otherwise unsurmountable barriers is predicted to cause quantum lubricity, a phenomenon which we expect should be observable in the recently implemented sliding cold ion experiments.

High-resolution of particle contacts via fluorophore exclusion in deep-imaging of jammed colloidal packings

NASA Astrophysics Data System (ADS)

Kyeyune-Nyombi, Eru; Morone, Flaviano; Liu, Wenwei; Li, Shuiqing; Gilchrist, M. Lane; Makse, Hernán A.

2018-01-01

Understanding the structural properties of random packings of jammed colloids requires an unprecedented high-resolution determination of the contact network providing mechanical stability to the packing. Here, we address the determination of the contact network by a novel strategy based on fluorophore signal exclusion of quantum dot nanoparticles from the contact points. We use fluorescence labeling schemes on particles inspired by biology and biointerface science in conjunction with fluorophore exclusion at the contact region. The method provides high-resolution contact network data that allows us to measure structural properties of the colloidal packing near marginal stability. We determine scaling laws of force distributions, soft modes, correlation functions, coordination number and free volume that define the universality class of jammed colloidal packings and can be compared with theoretical predictions. The contact detection method opens up further experimental testing at the interface of jamming and glass physics.

Porous silicon platform for optical detection of functionalized magnetic particles biosensing.

PubMed

Ko, Pil Ju; Ishikawa, Ryousuke; Sohn, Honglae; Sandhu, Adarsh

2013-04-01

The physical properties of porous materials are being exploited for a wide range of applications including optical biosensors, waveguides, gas sensors, micro capacitors, and solar cells. Here, we review the fast, easy and inexpensive electrochemical anodization based fabrication porous silicon (PSi) for optical biosensing using functionalized magnetic particles. Combining magnetically labeled biomolecules with PSi offers a rapid and one-step immunoassay and real-time detection by magnetic manipulation of superparamagnetic beads (SPBs) functionalized with target molecules onto corresponding probe molecules immobilized inside nano-pores of PSi. We first give an introduction to electrochemical and chemical etching procedures used to fabricate a wide range of PSi structures. Next, we describe the basic properties of PSi and underlying optical scattering mechanisms that govern their unique optical properties. Finally, we give examples of our experiments that demonstrate the potential of combining PSi and magnetic beads for real-time point of care diagnostics.

Review of heavy charged particle transport in MCNP6.2

NASA Astrophysics Data System (ADS)

Zieb, K.; Hughes, H. G.; James, M. R.; Xu, X. G.

2018-04-01

The release of version 6.2 of the MCNP6 radiation transport code is imminent. To complement the newest release, a summary of the heavy charged particle physics models used in the 1 MeV to 1 GeV energy regime is presented. Several changes have been introduced into the charged particle physics models since the merger of the MCNP5 and MCNPX codes into MCNP6. This paper discusses the default models used in MCNP6 for continuous energy loss, energy straggling, and angular scattering of heavy charged particles. Explanations of the physics models' theories are included as well.

Review of Heavy Charged Particle Transport in MCNP6.2

DOE PAGES

Zieb, Kristofer James Ekhart; Hughes, Henry Grady III; Xu, X. George; ...

2018-01-05

The release of version 6.2 of the MCNP6 radiation transport code is imminent. To complement the newest release, a summary of the heavy charged particle physics models used in the 1 MeV to 1 GeV energy regime is presented. Several changes have been introduced into the charged particle physics models since the merger of the MCNP5 and MCNPX codes into MCNP6. Here, this article discusses the default models used in MCNP6 for continuous energy loss, energy straggling, and angular scattering of heavy charged particles. Explanations of the physics models’ theories are included as well.

Pairwise Interaction Extended Point-Particle (PIEP) model for multiphase jets and sedimenting particles

NASA Astrophysics Data System (ADS)

Liu, Kai; Balachandar, S.

2017-11-01

We perform a series of Euler-Lagrange direct numerical simulations (DNS) for multiphase jets and sedimenting particles. The forces the flow exerts on the particles in these two-way coupled simulations are computed using the Basset-Bousinesq-Oseen (BBO) equations. These forces do not explicitly account for particle-particle interactions, even though such pairwise interactions induced by the perturbations from neighboring particles may be important especially when the particle volume fraction is high. Such effects have been largely unaddressed in the literature. Here, we implement the Pairwise Interaction Extended Point-Particle (PIEP) model to simulate the effect of neighboring particle pairs. A simple collision model is also applied to avoid unphysical overlapping of solid spherical particles. The simulation results indicate that the PIEP model provides a more elaborative and complicated movement of the dispersed phase (droplets and particles). Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) project N00014-16-1-2617.

Collective rotations of active particles interacting with obstacles

NASA Astrophysics Data System (ADS)

Mokhtari, Zahra; Aspelmeier, Timo; Zippelius, Annette

2017-10-01

We consider active particles in a heterogeneous medium, modeled by static, random obstacles. In accordance with the known tendency of active particles to cluster, we observe accumulation and crystallization of active particles around the obstacles which serve as nucleation sites. In the limit of high activity, the crystals start to rotate spontaneously, resembling a rotating rigid body. We trace the occurrence of these oscillations to the enhanced attraction of particles whose orientation points along the rotational velocity as compared to those whose orientation points in the opposite direction.

The Biostack Experiments I and II aboard Apollo 16 and 17.

PubMed

Bucker, H

1974-01-01

The concept of the Biostack experiment has become practicable through European scientific collaboration and with help of NASA. The objectives of this experiment flown aboard Apollo 16 and 17 are to study the biological effects of individual heavy cosmic particles of high-energy loss (HZE) not available on earth; to study the influence of additional spaceflight factors; to get some knowledge on the mechanism by which HZE particles damage biological materials; to get information on the spectrum of charge and energy of the cosmic ions in the spacecraft; to estimate the radiation hazards for man in space. For this purpose the Biostack experiment comprises a widespread spectrum of biological objects, and various radiobiological end-points are under investigation. Bacterial spores, protozoa cysts, plant seeds, shrimp eggs, and insect eggs were included in the Biostack experiment packages together with different physical radiation detectors (nuclear emulsions, plastics, AgCl crystals, and LiF thermoluminescence dosimeters). By using special arrangements of biological objects and physical track detectors, individual evaluation of tracks was obtained allowing the identification of each penetrating particle in relation to the possible biological effects on its path. The response of the different biological objects to space flight and HZE ions bombardment was of different degree, presumably depending on the ability of the organism to replace the cells damaged by a hit. The results help to estimate the radiation hazard for astronauts during space missions of long duration.

Aerosol Complexity and Implications for Predictability and Short-Term Forecasting

NASA Technical Reports Server (NTRS)

Colarco, Peter

2016-01-01

There are clear NWP and climate impacts from including aerosol radiative and cloud interactions. Changes in dynamics and cloud fields affect aerosol lifecycle, plume height, long-range transport, overall forcing of the climate system, etc. Inclusion of aerosols in NWP systems has benefit to surface field biases (e.g., T2m, U10m). Including aerosol affects has impact on analysis increments and can have statistically significant impacts on, e.g., tropical cyclogenesis. Above points are made especially with respect to aerosol radiative interactions, but aerosol-cloud interaction is a bigger signal on the global system. Many of these impacts are realized even in models with relatively simple (bulk) aerosol schemes (approx.10 -20 tracers). Simple schemes though imply simple representation of aerosol absorption and importantly for aerosol-cloud interaction particle-size distribution. Even so, more complex schemes exhibit a lot of diversity between different models, with issues such as size selection both for emitted particles and for modes. Prospects for complex sectional schemes to tune modal (and even bulk) schemes toward better selection of size representation. I think this is a ripe topic for more research -Systematic documentation of benefits of no vs. climatological vs. interactive (direct and then direct+indirect) aerosols. Document aerosol impact on analysis increments, inclusion in NWP data assimilation operator -Further refinement of baseline assumptions in model design (e.g., absorption, particle size distribution). Did not get into model resolution and interplay of other physical processes with aerosols (e.g., moist physics, obviously important), chemistry

Physics in ordered and disordered colloidal matter composed of poly(N-isopropylacrylamide) microgel particles.

PubMed

Yunker, Peter J; Chen, Ke; Gratale, Matthew D; Lohr, Matthew A; Still, Tim; Yodh, A G

2014-05-01

This review collects and describes experiments that employ colloidal suspensions to probe physics in ordered and disordered solids and related complex fluids. The unifying feature of this body of work is its clever usage of poly(N-isopropylacrylamide) (PNIPAM) microgel particles. These temperature-sensitive colloidal particles provide experimenters with a 'knob' for in situ control of particle size, particle interaction and particle packing fraction that, in turn, influence the structural and dynamical behavior of the complex fluids and solids. A brief summary of PNIPAM particle synthesis and properties is given, followed by a synopsis of current activity in the field. The latter discussion describes a variety of soft matter investigations including those that explore formation and melting of crystals and clusters, and those that probe structure, rearrangement and rheology of disordered (jammed/glassy) and partially ordered matter. The review, therefore, provides a snapshot of a broad range of physics phenomenology which benefits from the unique properties of responsive microgel particles.

BOOK REVIEW: Symmetry Breaking

NASA Astrophysics Data System (ADS)

Ryder, L. H.

2005-11-01

One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would have to be rather clever to recognize that the particle interactions were rotationally invariant. Nambu and Goldstone showed that the spontaneous breakdown of a (continuous) symmetry implied the existence of massless scalar particles, referred to as Nambu Goldstone bosons, or simply Goldstone bosons. Meanwhile Anderson, in his study of (non-relativistic) superconductivity, showed that the exclusion of magnetic flux (Meissner effect) corresponds to a finite range for the electromagnetic field and hence to a `massive photon'. In a relativistic context Englert, Brout, Guralnik and more particularly Higgs showed that a spontaneous breaking of a gauge symmetry resulted in a massive, instead of a massless, gauge particle and no Goldstone particle; in the jargon of the day, the massless gauge particle had `eaten' the massless Goldstone boson and become massive; exactly Anderson's observation. It is this phenomenon which has been invoked so successfully to explain the masses of the W and Z bosons of weak interactions. Spontaneous symmetry breaking, therefore, has played a major role in the development of the Standard Model of particle physics, and it has also proved an important tool in condensed matter physics, for example in the understanding of phase transitions. At the same time, however, in the understanding of most (or all) particle physicists, and perhaps also condensed matter physicists, the notion of spontaneous symmetry breaking has been inexorably linked to that of a degenerate vacuum. This is the background and the starting point for Strocchi's book. Recognizing the power and importance of the concept of spontaneous symmetry breaking in theoretical physics, he defines it in a more refined and general way than usual. `Despite the many popular accounts', he writes, `the phenomenon of spontaneous symmetry breaking is deep and subtle and it is not without [reason] that it has been fully understood only in recent times.' Strocchi's main emphasis is on the fact that the loss of symmetric behaviour requires both the existence of non-symmetric ground states and the infinite extension of the system. The book is divided into two parts, treating respectively the classical and quantum regimes. In classical field theory the symmetry breaking is explained in terms of the occurrence of disjoint sectors, or different phases, of a physical system. In the quantum regime the mechanism is characterized by a symmetry breaking order parameter, for which non-perturbative criteria are discussed, following the work of Wightman, in contrast to the usual Goldstone perturbative strategy. Strocchi's main interest is in condensed matter, rather than particle, physics, and the topics he covers include spin systems, Fermi and Bose gases and finite temperature field theory. The book is based on lectures given over a number of years. It is written in a pleasing style at a level suitable for graduate students in theoretical physics. While mathematically proper, it is not forbidding for a physics readership; the author is always aware this subject is a branch of physics. It should make profitable reading for many theoretical physicists.

Physical properties of dust particles in different comets inferred from observations and experimental simulations

NASA Astrophysics Data System (ADS)

Hadamcik, E.; Levasseur-Regourd, A. C.

2007-08-01

1.Introduction Remote observations of solar light scattered by cometary dust particles provide information on the dust properties for a large variety of comets, in complement to the exceptional in-situ observations (with or without sample returns). The scattered light is partially linearly polarized, with a polarization degree depending on the geometry of observations (phase angle ?) and on the physical properties of the particles. Differences in polarization have been found in cometary comae, pointing to different physical properties of the dust (e.g. sizes of the grains, of the aggregates, structures and porosities, complex refractive indices) [1, 2]. Such differences, as well as an observed polarimetric wavelength effect, tend to show that large aggregates made of submicron-sized grains could be present in some cometary comae regions [3, 4]. On the opposite, more compact particles seem to be present in other comae regions and/or comets [5, 6]. 2. Results We will present observations of different comets. The variations of the dust properties in the coma and their evolution will be discussed. The results will be compared to the results obtained by other observational techniques. On the images of comet 9P/Tempel 1 (at ?=41°) some hours after Deep Impact, two kinds of dust particles are detected: more compact particles with small velocities and fluffy particles ejected by the impact with larger velocities. On the images of comet 73P/Schwassmann-Wachmann 3, in the tail direction of fragment B, a disruption is observed. The dust coma around fragment C is more symmetric. For both A and B, important dust jets are ejected by the nucleus, which are visible on the intensity images in the solar and antisolar directions, and on the polarization maps. 3. Interpretation and conclusion Numerical (7,8,9) and experimental simulations provide an interpretation of the observations in terms of the physical properties of the particles. Experimental simulations have been performed on numerous levitating samples (compact and fluffy) with the PROGRA2 experiment, either in reduced gravity conditions (parabolic flights) [10,11], or lifted by an air-draught (laboratory conditions) [12,13]. The variations of the polarization are correlated to variations in the size of the grains and aggregates and are a function of the complex refractive index and its evolution. The correlation between the variations of the scattered intensity and the linear polarization maps allows us to disentangle different physical properties of the dust. The results are compared to results obtained from previous observations by the same methods. References [1] E. Hadamcik and A.C. Levasseur-Regourd, JQSRT 79-80, 661-678 (2003) [2] A.C. Levasseur-Regourd, E. Hadamcik, JQSRT 79-80, 903-910 (2003) [3] E. Hadamcik, A.C. Levasseur-Regourd, A&A 403, 757- 768 (2003) [4] L. Kolokolova et al., In: Comets II, M.C. Festou et al. (eds), pp 577 (2004) [5] E. Hadamcik, A.C. Levasseur-Regourd, Icarus 166, 188-194 (2003) [6] E. Hadamcik et al., Icarus, accepted. [7] J. Lasue, A.C. Levasseur-Regourd, JQSRT 100, 220-236 (2006) [8] H. Kimura et al., A&A 449, 1243-1254 (2006) [9] A.C. Levasseur-Regourd et al., PSS, in press, available on line (2007) [10] J.-B. Renard et al. Appl. Opt 41, 609-618 (2002) [11] J.-B. Renard et al., Adv. Space Res. 31, 2511-2518 (2003) [12] E. Hadamcik et al., JQSRT 100, 143-156 (2006) [13] E. Hadamcik et al., Icarus, in press, available on line (2007)

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Medium-heavy nuclei from nucleon-nucleon interactions in lattice QCD

NASA Astrophysics Data System (ADS)

Inoue, Takashi; Aoki, Sinya; Charron, Bruno; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji; HAL QCD Collaboration

2015-01-01

On the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon forces obtained from lattice QCD simulations, the properties of the medium-heavy doubly magic nuclei such as 16O and 40Ca are investigated. We found that those nuclei are bound for the pseudoscalar meson mass MPS≃470 MeV. The mass number dependence of the binding energies, single-particle spectra, and density distributions are qualitatively consistent with those expected from empirical data at the physical point, although these hypothetical nuclei at heavy quark mass have smaller binding energies than the real nuclei.

Occurrence and Characteristics of {sup 18}O-exchange Reactions Catalyzed By Sodium- and Potassium-dependent Adenosine Triphosphatases

DOE R&D Accomplishments Database

Dahms, A. S.; Boyer, P. D.

This discusses the following topics in High Energy Physics: The Particle Zoo; The Strong and the Weak; The Particle Explosion; Deep Inside the Nucleon; The Search for Unity; Physics in Collision; The Standard Model; Particles and the Cosmos; and Practical Benefits.

Lieb-Thirring inequality for a model of particles with point interactions

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

Frank, Rupert L.; Seiringer, Robert

2012-09-15

We consider a model of quantum-mechanical particles interacting via point interactions of infinite scattering length. In the case of fermions we prove a Lieb-Thirring inequality for the energy, i.e., we show that the energy is bounded from below by a constant times the integral of the particle density to the power (5/3).

Four-point functions and the permutation group S4

NASA Astrophysics Data System (ADS)

Eichmann, Gernot; Fischer, Christian S.; Heupel, Walter

2015-09-01

Four-point functions are at the heart of many interesting physical processes. A prime example is the light-by-light scattering amplitude, which plays an important role in the calculation of hadronic contributions to the anomalous magnetic moment of the muon. In the calculation of such quantities one faces the challenge of finding a suitable and well-behaved basis of tensor structures in coordinate and/or momentum space. Provided all (or many) of the external legs represent similar particle content, a powerful tool to construct and organize such bases is the permutation group S4. We introduce an efficient notation for dealing with the irreducible multiplets of S4, and we highlight the merits of this treatment by exemplifying four-point functions with gauge-boson legs such as the four-gluon vertex and the light-by-light scattering amplitude. The multiplet analysis is also useful for isolating the important kinematic regions and the dynamical singularity content of such amplitudes. Our analysis serves as a basis for future efficient calculations of these and similar objects.

A Genealogy of Convex Solids Via Local and Global Bifurcations of Gradient Vector Fields

NASA Astrophysics Data System (ADS)

Domokos, Gábor; Holmes, Philip; Lángi, Zsolt

2016-12-01

Three-dimensional convex bodies can be classified in terms of the number and stability types of critical points on which they can balance at rest on a horizontal plane. For typical bodies, these are non-degenerate maxima, minima, and saddle points, the numbers of which provide a primary classification. Secondary and tertiary classifications use graphs to describe orbits connecting these critical points in the gradient vector field associated with each body. In previous work, it was shown that these classifications are complete in that no class is empty. Here, we construct 1- and 2-parameter families of convex bodies connecting members of adjacent primary and secondary classes and show that transitions between them can be realized by codimension 1 saddle-node and saddle-saddle (heteroclinic) bifurcations in the gradient vector fields. Our results indicate that all combinatorially possible transitions can be realized in physical shape evolution processes, e.g., by abrasion of sedimentary particles.

56Fe particle exposure results in a long-lasting increase in a cellular index of genomic instability and transiently suppresses adult hippocampal neurogenesis in vivo

NASA Astrophysics Data System (ADS)

DeCarolis, Nathan A.; Rivera, Phillip D.; Ahn, Francisca; Amaral, Wellington Z.; LeBlanc, Junie A.; Malhotra, Shveta; Shih, Hung-Ying; Petrik, David; Melvin, Neal R.; Chen, Benjamin P. C.; Eisch, Amelia J.

2014-07-01

The high-LET HZE particles from galactic cosmic radiation pose tremendous health risks to astronauts, as they may incur sub-threshold brain injury or maladaptations that may lead to cognitive impairment. The health effects of HZE particles are difficult to predict and unfeasible to prevent. This underscores the importance of estimating radiation risks to the central nervous system as a whole as well as to specific brain regions like the hippocampus, which is central to learning and memory. Given that neurogenesis in the hippocampus has been linked to learning and memory, we investigated the response and recovery of neurogenesis and neural stem cells in the adult mouse hippocampal dentate gyrus after HZE particle exposure using two nestin transgenic reporter mouse lines to label and track radial glia stem cells (Nestin-GFP and Nestin-CreERT2/R26R:YFP mice, respectively). Mice were subjected to 56Fe particle exposure (0 or 1 Gy, at either 300 or 1000 MeV/n) and brains were harvested at early (24 h), intermediate (7 d), and/or long time points (2-3 mo) post-irradiation. 56Fe particle exposure resulted in a robust increase in 53BP1+ foci at both the intermediate and long time points post-irradiation, suggesting long-term genomic instability in the brain. However, 56Fe particle exposure only produced a transient decrease in immature neuron number at the intermediate time point, with no significant decrease at the long time point post-irradiation. 56Fe particle exposure similarly produced a transient decrease in dividing progenitors, with fewer progenitors labeled at the early time point but equal number labeled at the intermediate time point, suggesting a recovery of neurogenesis. Notably, 56Fe particle exposure did not change the total number of nestin-expressing neural stem cells. These results highlight that despite the persistence of an index of genomic instability, 56Fe particle-induced deficits in adult hippocampal neurogenesis may be transient. These data support the regenerative capacity of the adult SGZ after HZE particle exposure and encourage additional inquiry into the relationship between radial glia stem cells and cognitive function after HZE particle exposure.

A point particle model of lightly bound skyrmions

NASA Astrophysics Data System (ADS)

Gillard, Mike; Harland, Derek; Kirk, Elliot; Maybee, Ben; Speight, Martin

2017-04-01

A simple model of the dynamics of lightly bound skyrmions is developed in which skyrmions are replaced by point particles, each carrying an internal orientation. The model accounts well for the static energy minimizers of baryon number 1 ≤ B ≤ 8 obtained by numerical simulation of the full field theory. For 9 ≤ B ≤ 23, a large number of static solutions of the point particle model are found, all closely resembling size B subsets of a face centred cubic lattice, with the particle orientations dictated by a simple colouring rule. Rigid body quantization of these solutions is performed, and the spin and isospin of the corresponding ground states extracted. As part of the quantization scheme, an algorithm to compute the symmetry group of an oriented point cloud, and to determine its corresponding Finkelstein-Rubinstein constraints, is devised.

The phase transition of methane caused by pressure change during its seeping up from seepage, revealed by video observation and acoustic reflection data

NASA Astrophysics Data System (ADS)

Aoyama, C.

2017-12-01

Methane plumes often exist in the vicinity sea area where shallow type methane hydrates are extracted and they are observed as images displayed on monitors of multi-beam sonar and echo sounder onboard, where methane hydrates are expected at sea bottom on ROV observation data. The hydrates are generally considered to be generated in shallow depths below the sea floor. In this study, author examined annual amount of methane dissolving into seawater by measuring the amount of plume in order to make a quantification of dissolving methane from seafloor. Measurement procedure is plume exploration using multi-beam and quantitative echo sounder , submerge ROV to gushing point at seafloor , calculate the rising speed of methane plumes and examine the phases by monitoring seeping plumes from seafloor with high-definition camera. Components of seeping plumes were defined as methane hydrate particles based on the result by measuring water temperature. From this procedure, it can be concluded that the minimum rising speed of methane hydrate particles from gushing point is 1.6×10-1(m/s) and the maximum of 2.0×10-1(m/s) indicating a difference of more than ten times the gaseous theoretical value of 2.74(m/s). This speed is theoretically closer to the solid speed of the material with physical property similar to hydrates, which is 3.05×10-1 (m/s). Therefore, it can be determined that those particles are in the solid state, immediately above seafloor. To measure the amount of plumes seeping from gushing points funnel-shaped instruments with 20cm diameter opening were used to collect methane plumes in this sea area. This was performed in three different gushing points. As a result, 300ml of methane plume was collected in 643 seconds. Assuming that gushing points exist evenly in the sea area, the annual amount of methane gas seeping from these points will be 7.7×105m3 /per m2. Result shows a large quantity of methane seeping from seafloor into the water. This data is an important factor when considering carbon cycle and future development the shallow methane hydrate resources.

Measurement and Modeling of Electromagnetic Scattering by Particles and Particle Groups. Chapter 3

NASA Technical Reports Server (NTRS)

Mishchenko, Michael I.

2015-01-01

Small particles forming clouds of interstellar and circumstellar dust, regolith surfaces of many solar system bodies, and cometary atmospheres have a strong and often controlling effect on many ambient physical and chemical processes. Similarly, aerosol and cloud particles exert a strong influence on the regional and global climates of the Earth, other planets of the solar system, and exoplanets. Therefore, detailed and accurate knowledge of physical and chemical characteristics of such particles has the utmost scientific importance.

The Distribution of Interplanetary Dust between 0.96 and 1.04 au as Inferred from Impacts on the STEREO Spacecraft Observed by the Heliospheric Imagers

NASA Technical Reports Server (NTRS)

Davis, C. J.; Davis, J. A.; Meyer-Vernet, Nicole; Crothers, S.; Lintott, C.; Smith, A.; Bamford, S.; Baeten, E. M. L.; SaintCyr, O. C.; Campbell-Brown, M.;

Foam injection molding of elastomers with iron microparticles

NASA Astrophysics Data System (ADS)

Volpe, Valentina; D'Auria, Marco; Sorrentino, Luigi; Davino, Daniele; Pantani, Roberto

2015-12-01

In this work, a preliminary study of foam injection molding of a thermoplastic elastomer, Engage 8445, and its microcomposite loaded with iron particles was carried out, in order to evaluate the effect of the iron microparticles on the foaming process. In particular, reinforced samples have been prepared by using nanoparticles at 2% by volume. Nitrogen has been used as physical blowing agent. Foamed specimens consisting of neat and filled elastomer were characterized by density measurements and morphological analysis. While neat Engage has shown a well developed cellular morphology far from the injection point, the addition of iron microparticles considerably increased the homogeneity of the cellular morphology. Engage/iron foamed samples exhibited a reduction in density greater than 32%, with a good and homogeneous cellular morphology, both in the transition and in the core zones, starting from small distances from the injection point.

Short time propagation of a singular wave function: Some surprising results

NASA Astrophysics Data System (ADS)

Marchewka, A.; Granot, E.; Schuss, Z.

2007-08-01

The Schrödinger evolution of an initially singular wave function was investigated. First it was shown that a wide range of physical problems can be described by initially singular wave function. Then it was demonstrated that outside the support of the initial wave function the time evolution is governed to leading order by the values of the wave function and its derivatives at the singular points. Short-time universality appears where it depends only on a single parameter—the value at the singular point (not even on its derivatives). It was also demonstrated that the short-time evolution in the presence of an absorptive potential is different than in the presence of a nonabsorptive one. Therefore, this dynamics can be harnessed to the determination whether a potential is absorptive or not simply by measuring only the transmitted particles density.

Quantum Optics, Diffraction Theory, and Elementary Particle Physics

ScienceCinema

Glauber, Roy

2018-05-22

Physical optics has expanded greatly in recent years. Though it remains part of the ancestry of elementary particle physics, there are once again lessons to be learned from it. I shall discuss several of these, including some that have emerged at CERN and Brookhaven.

Latex-protein complexes from an acute phase recombinant antigen of Toxoplasma gondii for the diagnosis of recently acquired toxoplasmosis.

PubMed

Peretti, Leandro E; Gonzalez, Verónica D G; Marcipar, Iván S; Gugliotta, Luis M

2014-08-01

The synthesis and characterization of latex-protein complexes (LPC), from the acute phase recombinant antigen P35 (P35Ag) of Toxoplasma gondii and "core-shell" carboxylated or polystyrene (PS) latexes (of different sizes and charge densities) are considered, with the aim of producing immunoagglutination reagents able to detect recently acquired toxoplasmosis. Physical adsorption (PA) and chemical coupling (CC) of P35Ag onto latex particles at different pH were investigated. Greater amounts of adsorbed protein were obtained on PS latexes than on carboxylated latexes, indicating that hydrophobic forces govern the interactions between the protein and the particle surface. In the CC experiments, the highest amount of bound protein was obtained at pH 6, near the isoelectric point of the protein (IP=6.27). At this pH, it decreased both the repulsion between particle surface and protein, and the repulsion between neighboring molecules. The LPC were characterized and the antigenicity of the P35Ag protein coupled on the particles surface was evaluated by Enzyme-Linked ImmunoSorbent Assay (ELISA). Results from ELISA showed that the P35Ag coupled to the latex particles surface was not affected during the particles sensitization by PA and CC and the produced LPC were able to recognize specific anti-P35Ag antibodies present in the acute phase of the disease. Copyright © 2014 Elsevier B.V. All rights reserved.

Understanding large SEP events with the PATH code: Modeling of the 13 December 2006 SEP event

NASA Astrophysics Data System (ADS)

Verkhoglyadova, O. P.; Li, G.; Zank, G. P.; Hu, Q.; Cohen, C. M. S.; Mewaldt, R. A.; Mason, G. M.; Haggerty, D. K.; von Rosenvinge, T. T.; Looper, M. D.

2010-12-01

The Particle Acceleration and Transport in the Heliosphere (PATH) numerical code was developed to understand solar energetic particle (SEP) events in the near-Earth environment. We discuss simulation results for the 13 December 2006 SEP event. The PATH code includes modeling a background solar wind through which a CME-driven oblique shock propagates. The code incorporates a mixed population of both flare and shock-accelerated solar wind suprathermal particles. The shock parameters derived from ACE measurements at 1 AU and observational flare characteristics are used as input into the numerical model. We assume that the diffusive shock acceleration mechanism is responsible for particle energization. We model the subsequent transport of particles originated at the flare site and particles escaping from the shock and propagating in the equatorial plane through the interplanetary medium. We derive spectra for protons, oxygen, and iron ions, together with their time-intensity profiles at 1 AU. Our modeling results show reasonable agreement with in situ measurements by ACE, STEREO, GOES, and SAMPEX for this event. We numerically estimate the Fe/O abundance ratio and discuss the physics underlying a mixed SEP event. We point out that the flare population is as important as shock geometry changes during shock propagation for modeling time-intensity profiles and spectra at 1 AU. The combined effects of seed population and shock geometry will be examined in the framework of an extended PATH code in future modeling efforts.

Nano-Dust Analyzer for the detection and chemical composition measurement particles originating from near the Sun

NASA Astrophysics Data System (ADS)

OBrien, L. E.; Gemer, A.; Gruen, E.; Collette, A.; Horanyi, M.; Moebius, E.; Auer, S.; Juhasz, A.; Srama, R.; Sternovsky, Z.

2012-12-01

We report the development of the Nano-Dust Analyzer (NDA) instrument and the results from the first laboratory testing and calibration. The two STEREO spacecrafts have indicated that nano-sized dust particles, potentially with very high flux, are delivered to 1 AU from the inner solar system [Meyer-Vernet, N. et al., Solar Physics, 256, 463, 2009]. These particles are generated by collisional grinding or evaporation near the Sun and subsequently accelerated outward by the solar wind. The temporal variability and directionality are governed by conditions in the inner heliosphere and the mass analysis of the particles reveals the chemical differentiation of solid matter near the Sun. NDA is a highly sensitive dust analyzer that is developed under NASA's Heliophysics program. NDA is a linear time-of-flight mass analyzer that modeled after Cosmic Dust Analyzer (CDA) on Cassini and the more recent Lunar Dust EXperiment (LDEX) for the upcoming LADEE mission to the Moon. The ion optics of the instrument is optimized through numerical modeling. By applying technologies implemented in solar wind instruments and coronagraphs, the highly sensitive dust analyzer will be able to be pointed towards the solar direction. A laboratory prototype is built and tested and calibrated at the dust accelerator facility at the University of Colorado, Boulder, using particles with from 1 to over 50 km/s velocity.

Finite Density Condensation and Scattering Data: A Study in ϕ4 Lattice Field Theory

NASA Astrophysics Data System (ADS)

Gattringer, Christof; Giuliani, Mario; Orasch, Oliver

2018-06-01

We study the quantum field theory of a charged ϕ4 field in lattice regularization at finite density and low temperature in 2 and 4 dimensions with the goal of analyzing the connection of condensation phenomena to scattering data in a nonperturbative way. The sign problem of the theory at nonzero chemical potential μ is overcome by using a worldline representation for the Monte Carlo simulation. At low temperature we study the particle number as a function of μ and observe the steps for 1-, 2-, and 3-particle condensation. We determine the corresponding critical values μncrit , n =1 , 2, 3 and analyze their dependence on the spatial extent L of the lattice. Linear combinations of the μncrit give the interaction energies in the 2- and 3-particle sectors and their dependence on L is related to scattering data by Lüscher's formula and its generalizations to three particles. For two dimensions we determine the scattering phase shift and for four dimensions the scattering length. We cross-check our results with a determination of the mass and the 2- and 3-particle energies from conventional 2-, 4-, and 6-point correlators at zero chemical potential. The letter demonstrates that the physics of condensation at finite density and low temperature is closely related to scattering data of a quantum field theory.

Combining Newton's second law and de Broglie's particle-wave duality

NASA Astrophysics Data System (ADS)

Hill, James M.

2018-03-01

All matter can exhibit wave-like behaviour, and Louis de Broglie first predicted light to display the dual characteristics as both a collection of particles, called photons, or in some respects as a wave. The particle velocity is the group velocity of the wave, and if the particle velocity ug is subluminal then the associated wave or phase velocity up through the de Broglie relation ugup =c2 is necessarily superluminal. This is believed not to contradict the fact that information cannot be carried faster than the velocity of light c because the wave phase is supposed to carry no energy. However, the superluminal phase velocity may well be physically significant, and here we propose that the sub particle world and the super wave world might be equally important, and that each might exert an influence on the other, such that any mechanical equations must not only be Lorentz invariant but they must also be invariant under the transformation connecting the sub and super worlds. Following this approach, Einstein's equation E =mc2 becomes simply E = (m +m‧)c2 , where m and m‧ are masses given by Einstein expressions arising from the perceived sub and superluminal velocities ug and up respectively. This modification, although superficially simple, results from non-conventional physics and gives rise to an extension of Newton's second law, that might well account for the extra energy and mass that is known to exist in the universe, and referred to as dark energy and dark matter. An explicit solution for photons and light predicts a non-zero photon rest-mass m0 = hν / 2c2 , where h is Planck's constant and ν is the light frequency. Interestingly, the associated energy of this mass is the zero-point energy, believed to be the lowest energy that a quantum mechanical system may possess.

Elementary particle physics

NASA Technical Reports Server (NTRS)

Perkins, D. H.

1986-01-01

Elementary particle physics is discussed. Status of the Standard Model of electroweak and strong interactions; phenomena beyond the Standard Model; new accelerator projects; and possible contributions from non-accelerator experiments are examined.

A proposed physical analog for a quantum probability amplitude

NASA Astrophysics Data System (ADS)

Boyd, Jeffrey

What is the physical analog of a probability amplitude? All quantum mathematics, including quantum information, is built on amplitudes. Every other science uses probabilities; QM alone uses their square root. Why? This question has been asked for a century, but no one previously has proposed an answer. We will present cylindrical helices moving toward a particle source, which particles follow backwards. Consider Feynman's book QED. He speaks of amplitudes moving through space like the hand of a spinning clock. His hand is a complex vector. It traces a cylindrical helix in Cartesian space. The Theory of Elementary Waves changes direction so Feynman's clock faces move toward the particle source. Particles follow amplitudes (quantum waves) backwards. This contradicts wave particle duality. We will present empirical evidence that wave particle duality is wrong about the direction of particles versus waves. This involves a paradigm shift; which are always controversial. We believe that our model is the ONLY proposal ever made for the physical foundations of probability amplitudes. We will show that our ``probability amplitudes'' in physical nature form a Hilbert vector space with adjoints, an inner product and support both linear algebra and Dirac notation.

Three-Dimensional Stereoscopic Tracking Velocimetry and Experimental/Numerical Comparison of Directional Solidification

NASA Technical Reports Server (NTRS)

Lee, David; Ge, Yi; Cha, Soyoung Stephen; Ramachandran, Narayanan; Rose, M. Franklin (Technical Monitor)

2001-01-01

Measurement of three-dimensional (3-D) three-component velocity fields is of great importance in both ground and space experiments for understanding materials processing and fluid physics. The experiments in these fields most likely inhibit the application of conventional planar probes for observing 3-D phenomena. Here, we present the investigation results of stereoscopic tracking velocimetry (STV) for measuring 3-D velocity fields, which include diagnostic technology development, experimental velocity measurement, and comparison with analytical and numerical computation. STV is advantageous in system simplicity for building compact hardware and in software efficiency for continual near-real-time monitoring. It has great freedom in illuminating and observing volumetric fields from arbitrary directions. STV is based on stereoscopic observation of particles-Seeded in a flow by CCD sensors. In the approach, part of the individual particle images that provide data points is likely to be lost or cause errors when their images overlap and crisscross each other especially under a high particle density. In order to maximize the valid recovery of data points, neural networks are implemented for these two important processes. For the step of particle overlap decomposition, the back propagation neural network is utilized because of its ability in pattern recognition with pertinent particle image feature parameters. For the step of particle tracking, the Hopfield neural network is employed to find appropriate particle tracks based on global optimization. Our investigation indicates that the neural networks are very efficient and useful for stereoscopically tracking particles. As an initial assessment of the diagnostic technology performance, laminar water jets with and without pulsation are measured. The jet tip velocity profiles are in good agreement with analytical predictions. Finally, for testing in material processing applications, a simple directional solidification apparatus is built for experimenting with a metal analog of succinonitrile. Its 3-D velocity field at the liquid phase is then measured to be compared with those from numerical computation. Our theoretical, numerical, and experimental investigations have proven STV to be a viable candidate for reliably measuring 3-D flow velocities. With current activities are focused on further improving the processing efficiency, overall accuracy, and automation, the eventual efforts of broad experimental applications and concurrent numerical modeling validation will be vital to many areas in fluid flow and materials processing.

HIGH ENERGY PHYSICS: CERN Link Breathes Life Into Russian Physics.

PubMed

Stone, R

2000-10-13

Without fanfare, 600 Russian scientists here at CERN, the European particle physics laboratory, are playing key roles in building the Large Hadron Collider (LHC), a machine that will explore fundamental questions such as why particles have mass, as well as search for exotic new particles whose existence would confirm supersymmetry, a popular theory that aims to unify the four forces of nature. In fact, even though Russia is not one of CERN's 20 member states, most top high-energy physicists in Russia are working on the LHC. Some say their work could prove the salvation of high-energy physics back home.

Inflation scenario driven by a low energy physics inflaton

NASA Astrophysics Data System (ADS)

Ferreira, J. G.; Pires, C. A. de S.; Rodrigues, J. G.; Rodrigues da Silva, P. S.

2017-11-01

It is a longstanding desire of cosmologists, and particle physicists as well, to connect inflation to low energy physics, culminating, for instance, in what is known as Higgs inflation. The condition for the standard Higgs boson playing the role of the inflaton, and driving sucessfully inflation, is that it couples nonminimally with gravity. Nevertheless, cosmological constraints impose that the nonminimal coupling be large. This causes the loss of perturbative unitarity in a scale of energy far below the Planck one. Our aim in this work is to point out that inflaton potential containing a particular type of trilinear coupling involving the inflaton may circumvent this problem by realizing Higgs inflation with tiny nonminimal coupling of the inflaton with gravity. We then develop the idea within a toy model and implement it in the inverse type-II seesaw mechanism for small neutrinos masses.

BOOK REVIEW: The Legacy of Albert Einstein: A Collection of Essays in Celebration of the Year of Physics

NASA Astrophysics Data System (ADS)

Straumann, Norbert

2007-10-01

During the 'World Year of Physics' much has been written on the epoch-making 1905 papers of Albert Einstein and his later great contributions to physics. Why another book on the enormous impact of Einstein's work on 20th-century physics? The short answer is that the present collection of 13 relatively short essays on the legacy of Einstein by outstanding scientists is very pleasant to read and should be of interest to physicists of all branches. Beside looking back, most articles present later and topical developments, whose initiation began with the work of Einstein. During the year 2005, the growing recognition among physicists, historians, and philosophers of Einstein's revolutionary role in quantum theory was often emphasized. It is truly astonishing that most active physicists were largely unaware of this before. Fortunately, the article 'Einstein and the quantum' by V Singh puts the subject in perspective and describes all the main steps, beginning with the truly revolutionary 1905 paper on the light-quantum hypothesis and ending with Einstein's extension of the particle-wave duality to atoms and other particles in 1924 1925. The only point which, in my opinion, is not sufficiently emphasized in the discussion of the 1916 1917 papers on absorption and emission of radiation is the part on the momentum transfer in each elementary process. Einstein's result that there is a directed recoil hν/c—also for spontaneous emission—in complete contrast to classical theory, was particularly important to him. I enjoyed reading the articles on Brownian motion (S Majumdar), Bose Einstein condensation (N Kumar) and strongly correlated electrons (T Ramakrishnan), which are all written for non-experts. Connected with Einstein's most lasting work—general relativity—there are two articles on cosmology. The one by J Narlikar gives a brief historical account of the development that was initiated by the 1917 paper of Einstein. S Sarkar's essay emphasizes the remarkable recent observational progress in cosmology and the emergence of the 'cosmic concordance model', with dark matter and dark energy as the dominant components of the current universe. Their discovery is widely considered as the most direct evidence for fundamental physics beyond the standard model of particle physics. In an introductory section Sarkar recalls the main reasons why the cosmological constant (vacuum energy) problem is of a very profound nature. In spite of some interesting ideas, no satisfactory solution is in sight. The article by B Sathyapakhash on gravitational radiation provides a readable introduction to the status of current detectors and astronomical sources of gravitational radiation. Of great cosmological interest are planned searches for a stochastic background of gravitational waves that is expected to have been produced by quantum processes in the very early universe. More than the first third of the book is devoted to current speculative attempts at creating a quantum theory of gravity, possibly within a unified coherent description of the known four fundamental interactions. Thanks to the enormously large value of the Planck energy in comparison to elementary particle masses, physicists may maintain for a long time, with success, a schizophrenic attitude in working within the framework of our present understanding, based on quantum field theory and classical general relativity. That physics cannot stay with that was already pointed out by Einstein in 1916, as A Ashtekar recalls in his essay. 'Einstein and the search for unification' by D Gross is the first article of the present book. In this he describes the reasons why, for those working in speculative areas, 'Einstein remains an inspiration for his foresight, and his unyielding determination and courage'. This inspiration is also manifest in the essays by M Atiyah, A Sen, and A Dabholkar on string theory. Hopefully, this book will find many readers, especially among graduate students, who can get valuable impressions of what is interesting in physics and what some of the main open problems for future research are.

News Teaching: The epiSTEMe project: KS3 maths and science improvement Field trip: Pupils learn physics in a stately home Conference: ShowPhysics welcomes fun in Europe Student numbers: Physics numbers increase in UK Tournament: Physics tournament travels to Singapore Particle physics: Hadron Collider sets new record Astronomy: Take your classroom into space Forthcoming Events

NASA Astrophysics Data System (ADS)

2010-05-01

Teaching: The epiSTEMe project: KS3 maths and science improvement Field trip: Pupils learn physics in a stately home Conference: ShowPhysics welcomes fun in Europe Student numbers: Physics numbers increase in UK Tournament: Physics tournament travels to Singapore Particle physics: Hadron Collider sets new record Astronomy: Take your classroom into space Forthcoming Events

Fact Sheets and Brochures | News

Science.gov Websites

Illinois Accelerator Research Center Economic Impact Particle Physics: Benefits to Society The Fermilab Saturday Morning Physics What are neutrinos? What are neutrinos? (large format) What is a Higgs boson? U.S Public Outreach America's particle physics and accelerator laboratory LBNF/DUNE - An international mega

Design Considerations for High Energy Electron -- Positron Storage Rings

DOE R&D Accomplishments Database

Richter, B.

1966-11-01

High energy electron-positron storage rings give a way of making a new attack on the most important problems of elementary particle physics. All of us who have worked in the storage ring field designing, building, or using storage rings know this. The importance of that part of storage ring work concerning tests of quantum electrodynamics and mu meson physics is also generally appreciated by the larger physics community. However, I do not think that most of the physicists working tin the elementary particle physics field realize the importance of the contribution that storage ring experiments can make to our understanding of the strongly interacting particles. I would therefore like to spend the next few minutes discussing the sort of things that one can do with storage rings in the strongly interacting particle field.

Particle Detectors

NASA Astrophysics Data System (ADS)

Grupen, Claus; Shwartz, Boris

2011-09-01

Preface to the first edition; Preface to the second edition; Introduction; 1. Interactions of particles and radiation with matter; 2. Characteristic properties of detectors; 3. Units of radiation measurements and radiation sources; 4. Accelerators; 5. Main physical phenomena used for particle detection and basic counter types; 6. Historical track detectors; 7. Track detectors; 8. Calorimetry; 9. Particle identification; 10. Neutrino detectors; 11. Momentum measurement and muon detection; 12. Ageing and radiation effects; 13. Example of a general-purpose detector: Belle; 14. Electronics; 15. Data analysis; 16. Applications of particle detectors outside particle physics; 17. Glossary; 18. Solutions; 19. Resumé; Appendixes; Index.

Belle2VR: A Virtual-Reality Visualization of Subatomic Particle Physics in the Belle II Experiment.

PubMed

Duer, Zach; Piilonen, Leo; Glasson, George

2018-05-01

Belle2VR is an interactive virtual-reality visualization of subatomic particle physics, designed by an interdisciplinary team as an educational tool for learning about and exploring subatomic particle collisions. This article describes the tool, discusses visualization design decisions, and outlines our process for collaborative development.

Lithium Gadolinium Borate in Plastic Scintillator as an Antineutrino Detection Material

DTIC Science & Technology

2010-06-01

advancement of fundamental particle physics, development of the standard model of particle physics and our understanding many cosmological processes...MeVee). Where the light produced by by a 1MeV electron is 1 MeVee by definition , but a heavy charged particle would have a kinetic energy of several

Teaching Particle Physics in the Open University's Science Foundation Course.

ERIC Educational Resources Information Center

Farmelo, Graham

1992-01-01

Discusses four topics presented in the science foundation course of the Open University that exemplify current developments in particle physics, in particular, and that describe important issues about the nature of science, in general. Topics include the omega minus particle, the diversity of quarks, the heavy lepton, and the discovery of the W…

Future particle-physics projects in the United States

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

Denisov, D. S., E-mail: denisovd@fnal.gov

2015-07-15

Basic proposals of experiments aimed at precision measurements of Standard Model parameters and at searches for new particles, including dark-matter particles, are described along with future experimental projects considered by American Physical Society at the meeting in the summer of 2013 and intended for implementation within the next ten to twenty years.

Future particle-physics projects in the United States

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

Denisov, D. S.

2015-08-25

Basic proposals of experiments aimed at precision measurements of Standard Model parameters and at searches for new particles, including dark-matter particles, are described along with future experimental projects considered by American Physical Society at the meeting in the summer of 2013 and intended for implementation within the next ten to twenty years.

Comprehensive model for predicting elemental composition of coal pyrolysis products

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

Ricahrds, Andrew P.; Shutt, Tim; Fletcher, Thomas H.

Large-scale coal combustion simulations depend highly on the accuracy and utility of the physical submodels used to describe the various physical behaviors of the system. Coal combustion simulations depend on the particle physics to predict product compositions, temperatures, energy outputs, and other useful information. The focus of this paper is to improve the accuracy of devolatilization submodels, to be used in conjunction with other particle physics models. Many large simulations today rely on inaccurate assumptions about particle compositions, including that the volatiles that are released during pyrolysis are of the same elemental composition as the char particle. Another common assumptionmore » is that the char particle can be approximated by pure carbon. These assumptions will lead to inaccuracies in the overall simulation. There are many factors that influence pyrolysis product composition, including parent coal composition, pyrolysis conditions (including particle temperature history and heating rate), and others. All of these factors are incorporated into the correlations to predict the elemental composition of the major pyrolysis products, including coal tar, char, and light gases.« less

Behavior of micro-particles in monolith ceramic membrane filtration with pre-coagulation.

PubMed

Yonekawa, H; Tomita, Y; Watanabe, Y

2004-01-01

This paper is intended to clarify the characteristics unique to monolith ceramic membranes with pre-coagulation by referring to the behavior of micro-particles. Flow analysis and experiments have proved that monolith ceramic membranes show a unique flow pattern in the channels within the element, causing extremely rapid flocculation in the channel during dead-end filtration. It was assumed that charge-neutralized micro-particles concentrated near the membrane surface grow in size due to flocculation, and as a result, coarse micro-particles were taken up by the shearing force to flow out. As the dead end points of flow in all the channels are located near the end of the channels with higher filterability, most of the flocculated coarse particles are formed to a columnar cake intensively at the dead end point. Therefore cake layer forming on the membrane other than around the dead end point is alleviated. This behavior of particle flocculation and cake formation at the dead end point within the channels are unique characteristics of monolith ceramic membranes. This is why all monolith ceramic membrane water purification systems operating in Japan do not have pretreatment equipment for flocculation and sedimentation.

Learning about a Level Physics Students' Understandings of Particle Physics Using Concept Mapping

ERIC Educational Resources Information Center

Gourlay, H.

2017-01-01

This paper describes a small-scale piece of research using concept mapping to elicit A level students' understandings of particle physics. Fifty-nine year 12 (16- and 17 year-old) students from two London schools participated. The exercise took place during school physics lessons. Students were instructed how to make a concept map and were…

EDITORIAL: Focus on Dark Matter and Particle Physics

NASA Astrophysics Data System (ADS)

Aprile, Elena; Profumo, Stefano

2009-10-01

The quest for the nature of dark matter has reached a historical point in time, with several different and complementary experiments on the verge of conclusively exploring large portions of the parameter space of the most theoretically compelling particle dark matter models. This focus issue on dark matter and particle physics brings together a broad selection of invited articles from the leading experimental and theoretical groups in the field. The leitmotif of the collection is the need for a multi-faceted search strategy that includes complementary experimental and theoretical techniques with the common goal of a sound understanding of the fundamental particle physical nature of dark matter. These include theoretical modelling, high-energy colliders and direct and indirect searches. We are confident that the works collected here present the state of the art of this rapidly changing field and will be of interest to both experts in the topic of dark matter as well as to those new to this exciting field. Focus on Dark Matter and Particle Physics Contents DARK MATTER AND ASTROPHYSICS Scintillator-based detectors for dark matter searches I S K Kim, H J Kim and Y D Kim Cosmology: small-scale issues Joel R Primack Big Bang nucleosynthesis and particle dark matter Karsten Jedamzik and Maxim Pospelov Particle models and the small-scale structure of dark matter Torsten Bringmann DARK MATTER AND COLLIDERS Dark matter in the MSSM R C Cotta, J S Gainer, J L Hewett and T G Rizzo The role of an e+e- linear collider in the study of cosmic dark matter M Battaglia Collider, direct and indirect detection of supersymmetric dark matter Howard Baer, Eun-Kyung Park and Xerxes Tata INDIRECT PARTICLE DARK MATTER SEARCHES:EXPERIMENTS PAMELA and indirect dark matter searches M Boezio et al An indirect search for dark matter using antideuterons: the GAPS experiment C J Hailey Perspectives for indirect dark matter search with AMS-2 using cosmic-ray electrons and positrons B Beischer, P von Doetinchem, H Gast, T Kirn and S Schael Axion searches with helioscopes and astrophysical signatures for axion(-like) particles K Zioutas, M Tsagri, Y Semertzidis, T Papaevangelou, T Dafni and V Anastassopoulos The indirect search for dark matter with IceCube Francis Halzen and Dan Hooper DIRECT DARK MATTER SEARCHES:EXPERIMENTS Gaseous dark matter detectors G Sciolla and C J Martoff Search for dark matter with CRESST Rafael F Lang and Wolfgang Seidel DIRECT AND INDIRECT PARTICLE DARK MATTER SEARCHES:THEORY Dark matter annihilation around intermediate mass black holes: an update Gianfranco Bertone, Mattia Fornasa, Marco Taoso and Andrew R Zentner Update on the direct detection of dark matter in MSSM models with non-universal Higgs masses John Ellis, Keith A Olive and Pearl Sandick Dark stars: a new study of the first stars in the Universe Katherine Freese, Peter Bodenheimer, Paolo Gondolo and Douglas Spolyar Determining the mass of dark matter particles with direct detection experiments Chung-Lin Shan The detection of subsolar mass dark matter halos Savvas M Koushiappas Neutrino coherent scattering rates at direct dark matter detectors Louis E Strigari Gamma rays from dark matter annihilation in the central region of the Galaxy Pasquale Dario Serpico and Dan Hooper DARK MATTER MODELS The dark matter interpretation of the 511 keV line Céline Boehm Axions as dark matter particles Leanne D Duffy and Karl van Bibber Sterile neutrinos Alexander Kusenko Dark matter candidates Lars Bergström Minimal dark matter: model and results Marco Cirelli and Alessandro Strumia Shedding light on the dark sector with direct WIMP production Partha Konar, Kyoungchul Kong, Konstantin T Matchev and Maxim Perelstein Axinos as dark matter particles Laura Covi and Jihn E Kim

Particle transport and deposition: basic physics of particle kinetics

PubMed Central

Tsuda, Akira; Henry, Frank S.; Butler, James P.

2015-01-01

The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. Whereas the particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drug. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this chapter. A large portion of this chapter deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: 1) the physical characteristics of particles, 2) particle behavior in gas flow, and 3) gas flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The chapter concludes with a summary and a brief discussion of areas of future research. PMID:24265235

36th International Conference on High Energy Physics

NASA Astrophysics Data System (ADS)

The Australian particle physics community was honoured to host the 36th ICHEP conference in 2012 in Melbourne. This conference has long been the reference event for our international community. The announcement of the discovery of the Higgs boson at the LHC was a major highlight, with huge international press coverage. ICHEP2012 was described by CERN Director-General, Professor Rolf Heuer, as a landmark conference for our field. In additional to the Higgs announcement, important results from neutrino physics, from flavour physics, and from physics beyond the standard model also provided great interest. There were also updates on key accelerator developments such as the new B-factories, plans for the LHC upgrade, neutrino facilities and associated detector developments. ICHEP2012 exceeded the promise expected of the key conference for our field, and really did provide a reference point for the future. Many thanks to the contribution reviewers: Andy Bakich, Csaba Balazs, Nicole Bell, Catherine Buchanan, Will Crump, Cameron Cuthbert, Ben Farmer, Sudhir Gupta, Elliot Hutchison, Paul Jackson, Geng-Yuan Jeng, Archil Kobakhidze, Doyoun Kim, Tong Li, Antonio Limosani (Head Editor), Kristian McDonald, Nikhul Patel, Aldo Saavedra, Mark Scarcella, Geoff Taylor, Ian Watson, Graham White, Tony Williams and Bruce Yabsley.

Solution of effective Hamiltonian of impurity hopping between two sites in a metal

NASA Astrophysics Data System (ADS)

Ye, Jinwu

1998-03-01

We analyze in detail all the possible fixed points of the effective Hamiltonian of a non-magnetic impurity hopping between two sites in a metal obtained by Moustakas and Fisher(MF). We find a line of non-fermi liquid fixed points which continuously interpolates between the 2-channel Kondo fixed point(2CK) and the one channel, two impurity Kondo (2IK) fixed point. There is one relevant direction with scaling dimension 1/2 and one leading irrelevant operator with dimension 3/2. There is also one marginal operator in the spin sector moving along this line. The additional non-fermi liquid fixed point found by MF has the same symmetry as the 2IK, it has two relevant directions with scaling dimension 1/2, therefore also unstable. The system is shown to flow to a line of fermi-liquid fixed points which continuously interpolates between the non-interacting fixed point and the 2 channel spin-flavor Kondo fixed point (2CSFK) discussed by the author previously. The effect of particle-hole symmetry breaking is discussed. The effective Hamiltonian in the external magnetic field is analysed. The scaling functions for the physical measurable quantities are derived in the different regimes; their predictions for the experiments are given. Finally the implications are given for a non-magnetic impurity hopping around three sites with triangular symmetry discussed by MF.

Application of particle swarm optimization in path planning of mobile robot

NASA Astrophysics Data System (ADS)

Wang, Yong; Cai, Feng; Wang, Ying

2017-08-01

In order to realize the optimal path planning of mobile robot in unknown environment, a particle swarm optimization algorithm based on path length as fitness function is proposed. The location of the global optimal particle is determined by the minimum fitness value, and the robot moves along the points of the optimal particles to the target position. The process of moving to the target point is done with MATLAB R2014a. Compared with the standard particle swarm optimization algorithm, the simulation results show that this method can effectively avoid all obstacles and get the optimal path.

Cryogenic techniques for large superconducting magnets in space

NASA Technical Reports Server (NTRS)

Green, M. A.

1989-01-01

A large superconducting magnet is proposed for use in a particle astrophysics experiment, ASTROMAG, which is to be mounted on the United States Space Station. This experiment will have a two-coil superconducting magnet with coils which are 1.3 to 1.7 meters in diameter. The two-coil magnet will have zero net magnetic dipole moment. The field 15 meters from the magnet will approach earth's field in low earth orbit. The issue of high Tc superconductor will be discussed in the paper. The reasons for using conventional niobium-titanium superconductor cooled with superfluid helium will be presented. Since the purpose of the magnet is to do particle astrophysics, the superconducting coils must be located close to the charged particle detectors. The trade off between the particle physics possible and the cryogenic insulation around the coils is discussed. As a result, the ASTROMAG magnet coils will be operated outside of the superfluid helium storage tank. The fountain effect pumping system which will be used to cool the coil is described in the report. Two methods for extending the operating life of the superfluid helium dewar are discussed. These include: operation with a third shield cooled to 90 K with a sterling cycle cryocooler, and a hybrid cryogenic system where there are three hydrogen-cooled shields and cryostat support heat intercept points.

Movement and collision of Lagrangian particles in hydro-turbine intakes: a case study

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

Romero-Gomez, Pedro; Richmond, Marshall C.

Studies of the stress/survival of migratory fish during downstream passage through operating hydro-turbines are normally conducted to determine the fish-friendliness of units. One field approach consisting of recording extreme hydraulics with autonomous sensors is largely sensitive to the conditions of sensor release and the initial trajectories at the turbine intake. This study applies a modelling strategy based on flow simulations using computational fluid dynamics and Lagrangian particle tracking to represent the travel of live fish and autonomous sensor devices through hydro-turbine intakes. For the flow field calculation, the simulations were conducted with both a time-averaging turbulence model and an eddy-resolvingmore » technique. For the particle tracking calculation, different modelling assumptions for turbulence forcing, mass formulation, buoyancy, and release condition were tested. The modelling assumptions are evaluated with respect to data sets collected using a laboratory physical model and an autonomous sensor device deployed at Ice Harbor Dam (Snake River, State of Washington, U.S.A.) at the same discharge and release point as in the present computer simulations. We found an acceptable agreement between the simulated results and observed data and discuss relevant features of Lagrangian particle movement that are critical in turbine design and in the experimental design of field studies.« less

Susceptibility of contrail ice crystal numbers to aircraft soot particle emissions

NASA Astrophysics Data System (ADS)

Kärcher, B.; Voigt, C.

2017-08-01

We develop an idealized, physically based model describing combined effects of ice nucleation and sublimation on ice crystal number during persistent contrail formation. Our study represents the first effort to predict ice numbers at the point where contrails transition into contrail cirrus—several minutes past formation—by connecting them to aircraft soot particle emissions and atmospheric supersaturation with respect to ice. Results averaged over an observed exponential distribution of ice supersaturation (mean value 15%) indicate that large reductions in soot particle numbers are needed to lower contrail ice crystal numbers significantly for soot emission indices around 1015 (kg fuel)-1, because reductions in nucleated ice number are partially compensated by sublimation losses. Variations in soot particle (-50%) and water vapor (+10%) emission indices at threefold lower soot emissions resulting from biofuel blending cause ice crystal numbers to change by -35% and <5%, respectively. The efficiency of reduction depends on ice supersaturation and the size distribution of nucleated ice crystals in jet exhaust plumes and on atmospheric ice supersaturation, making the latter another key factor in contrail mitigation. We expect our study to have important repercussions for planning airborne measurements targeting contrail formation, designing parameterization schemes for use in large-scale models, reducing uncertainties in predicting contrail cirrus, and mitigating the climate impact of aviation.

Synthesis of sub-10 nm solid lipid nanoparticles for topical and biomarker detection applications

NASA Astrophysics Data System (ADS)

Calderón-Colón, Xiomara; Patchan, Marcia W.; Theodore, Mellisa L.; Le, Huong T.; Sample, Jennifer L.; Benkoski, Jason J.; Patrone, Julia B.

2014-02-01

Solid lipid nanoparticles (SLNs) are a promising platform for sensing in vivo biomarkers due to their biocompatibility, stability, and their ability to carry a wide range of active ingredients. The skin is a prominent target organ for numerous inflammatory and stress-related biomarkers, making it an excellent site for early detection of physiological imbalance and application of sensory nanoparticles. Though smaller particle size has generally been correlated with increased penetration of skin models, there has been little attention paid to the significance of other nanoparticle synthesis parameters with respect to their physical properties. In this study, we demonstrate the synthesis of sub-10 nm SLNs by the phase inversion temperature (PIT) method. These particles were specifically designed for topical delivery of hydrogen peroxide-detecting chemiluminescent dyes. A systematic design of experiments approach was used to investigate the role of the processing variables on SLN form and properties. The processing variables were correlated with the SLN properties (e.g., dye solubility, phase inversion temperature, particle size, polydispersity, melting point, and latent heat of melting). Statistical analysis revealed that the PIT method, while allowing total control over the thermal properties, resulted in well-controlled synthesis of ultra-small particles, while allowing great flexibility in the processing conditions and incorporated compounds.

Scientific program and abstracts

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

Gerich, C.

1983-01-01

The Fifth International Conference on High-Power Particle Beams is organized jointly by the Lawrence Livermore National Laboratory and Physics International Company. As in the previous conferences in this series, the program includes the following topics: high-power, electron- and ion-beam acceleration and transport; diode physics; high-power particle beam interaction with plasmas and dense targets; particle beam fusion (inertial confinement); collective ion acceleration; particle beam heating of magnetically confined plasmas; and generation of microwave/free-electron lasers.

The Learning Reconstruction of Particle System and Linear Momentum Conservation in Introductory Physics Course

NASA Astrophysics Data System (ADS)

Karim, S.; Saepuzaman, D.; Sriyansyah, S. P.

2016-08-01

This study is initiated by low achievement of prospective teachers in understanding concepts in introductory physics course. In this case, a problem has been identified that students cannot develop their thinking skills required for building physics concepts. Therefore, this study will reconstruct a learning process, emphasizing a physics concept building. The outcome will design physics lesson plans for the concepts of particle system as well as linear momentum conservation. A descriptive analysis method will be used in order to investigate the process of learning reconstruction carried out by students. In this process, the students’ conceptual understanding will be evaluated using essay tests for concepts of particle system and linear momentum conservation. The result shows that the learning reconstruction has successfully supported the students’ understanding of physics concept.

Statistical Physics Experiments Using Dusty Plasmas

NASA Astrophysics Data System (ADS)

Goree, John

2016-10-01

Compared to other areas of physics research, Statistical Physics is heavily dominated by theory, with comparatively little experiment. One reason for the lack of experiments is the impracticality of tracking of individual atoms and molecules within a substance. Thus, there is a need for a different kind of experimental system, one where individual particles not only move stochastically as they collide with one another, but also are large enough to allow tracking. A dusty plasma can meet this need. A dusty plasma is a partially ionized gas containing small particles of solid matter. These micron-size particles gain thousands of electronic charges by collecting more electrons than ions. Their motions are dominated by Coulomb collisions with neighboring particles. In this so-called strongly coupled plasma, the dust particles self-organize in much the same way as atoms in a liquid or solid. Unlike atoms, however, these particles are large and slow, so that they can be tracked easily by video microscopy. Advantages of dusty plasma for experimental statistical physics research include particle tracking, lack of frictional contact with solid surfaces, and avoidance of overdamped motion. Moreover, the motion of a collection of dust particles can mimic an equilibrium system with a Maxwellian velocity distribution, even though the dust particles themselves are not truly in thermal equilibrium. Nonequilibrium statistical physics can be studied by applying gradients, for example by imposing a shear flow. In this talk I will review some of our recent experiments with shear flow. First, we performed the first experimental test to verify the Fluctuation Theorem for a shear flow, showing that brief violations of the Second Law of Thermodynamics occur with the predicted probabilities, for a small system. Second, we discovered a skewness of a shear-stress distribution in a shear flow. This skewness is a phenomenon that likely has wide applicability in nonequilibrium steady states. Third, we performed the first experimental test of a statistical physics theory (the Green-Kubo model) that is widely used by physical chemists to compute viscosity coefficients, and we found that it fails. Work supported by the U.S. Department of Energy, NSF, and NASA.

Bell violation in the sky

NASA Astrophysics Data System (ADS)

Choudhury, Sayantan; Panda, Sudhakar; Singh, Rajeev

2017-02-01

In this work, we have studied the possibility of setting up Bell's inequality violating experiment in the context of cosmology, based on the basic principles of quantum mechanics. First we start with the physical motivation of implementing the Bell inequality violation in the context of cosmology. Then to set up the cosmological Bell violating test experiment we introduce a model independent theoretical framework using which we have studied the creation of new massive particles by implementing the WKB approximation method for the scalar fluctuations in the presence of additional time-dependent mass contribution in the cosmological perturbation theory. Here for completeness we compute the total number density and the energy density of the newly created particles in terms of the Bogoliubov coefficients using the WKB approximation method. Next using the background scalar fluctuation in the presence of a new time-dependent mass contribution, we explicitly compute the expression for the one point and two point correlation functions. Furthermore, using the results for a one point function we introduce a new theoretical cosmological parameter which can be expressed in terms of the other known inflationary observables and can also be treated as a future theoretical probe to break the degeneracy amongst various models of inflation. Additionally, we also fix the scale of inflation in a model-independent way without any prior knowledge of primordial gravitational waves. Also using the input from a newly introduced cosmological parameter, we finally give a theoretical estimate for the tensor-to-scalar ratio in a model-independent way. Next, we also comment on the technicalities of measurements from isospin breaking interactions and the future prospects of newly introduced massive particles in a cosmological Bell violating test experiment. Further, we cite a precise example of this setup applicable in the context of string theory motivated axion monodromy model. Then we comment on the explicit role of the decoherence effect and high spin on cosmological Bell violating test experiment. Finally, we provide a theoretical bound on the heavy particle mass parameter for scalar fields, gravitons and other high spin fields from our proposed setup.

Mechanisms for the clustering of inertial particles in the inertial range of isotropic turbulence

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

Bragg, Andrew D.; Ireland, Peter J.; Collins, Lance R.

2015-08-27

In this study, we consider the physical mechanism for the clustering of inertial particles in the inertial range of isotropic turbulence. We analyze the exact, but unclosed, equation governing the radial distribution function (RDF) and compare the mechanisms it describes for clustering in the dissipation and inertial ranges. We demonstrate that in the limit St r <<1, where St r is the Stokes number based on the eddy turnover time scale at separation r, the clustering in the inertial range can be understood to be due to the preferential sampling of the coarse-grained fluid velocity gradient tensor at that scale.more » When St r≳O(1) this mechanism gives way to a nonlocal clustering mechanism. These findings reveal that the clustering mechanisms in the inertial range are analogous to the mechanisms that we identified for the dissipation regime. Further, we discuss the similarities and differences between the clustering mechanisms we identify in the inertial range and the “sweep-stick” mechanism developed by Coleman and Vassilicos. We show that the idea that initial particles are swept along with acceleration stagnation points is only approximately true because there always exists a finite difference between the velocity of the acceleration stagnation points and the local fluid velocity. This relative velocity is sufficient to allow particles to traverse the average distance between the stagnation points within the correlation time scale of the acceleration field. We also show that the stick part of the mechanism is only valid for St r<<1 in the inertial range. We emphasize that our clustering mechanism provides the more fundamental explanation since it, unlike the sweep-stick mechanism, is able to explain clustering in arbitrary spatially correlated velocity fields. We then consider the closed, model equation for the RDF given in Zaichik and Alipchenkov and use this, together with the results from our analysis, to predict the analytic form of the RDF in the inertial range for St r<<1, which, unlike that in the dissipation range, is not scale invariant. Finally, the results are in good agreement with direct numerical simulations, provided the separations are well within the inertial range.« less

Coarse-graining to the meso and continuum scales with molecular-dynamics-like models

NASA Astrophysics Data System (ADS)

Plimpton, Steve

Many engineering-scale problems that industry or the national labs try to address with particle-based simulations occur at length and time scales well beyond the most optimistic hopes of traditional coarse-graining methods for molecular dynamics (MD), which typically start at the atomic scale and build upward. However classical MD can be viewed as an engine for simulating particles at literally any length or time scale, depending on the models used for individual particles and their interactions. To illustrate I'll highlight several coarse-grained (CG) materials models, some of which are likely familiar to molecular-scale modelers, but others probably not. These include models for water droplet freezing on surfaces, dissipative particle dynamics (DPD) models of explosives where particles have internal state, CG models of nano or colloidal particles in solution, models for aspherical particles, Peridynamics models for fracture, and models of granular materials at the scale of industrial processing. All of these can be implemented as MD-style models for either soft or hard materials; in fact they are all part of our LAMMPS MD package, added either by our group or contributed by collaborators. Unlike most all-atom MD simulations, CG simulations at these scales often involve highly non-uniform particle densities. So I'll also discuss a load-balancing method we've implemented for these kinds of models, which can improve parallel efficiencies. From the physics point-of-view, these models may be viewed as non-traditional or ad hoc. But because they are MD-style simulations, there's an opportunity for physicists to add statistical mechanics rigor to individual models. Or, in keeping with a theme of this session, to devise methods that more accurately bridge models from one scale to the next.

PEOPLE IN PHYSICS: Interview with Peter Higgs

NASA Astrophysics Data System (ADS)

Fancey, Conducted by Norman

1998-01-01

Peter Higgs, FRSE, FRS held until recently a personal chair in theoretical physics at the University of Edinburgh and is now an emeritus professor. Peter is well known for predicting the existence of a new particle, the Higgs boson - as yet unconfirmed. He has been awarded a number of prizes in recognition of his work, most recently the Paul Dirac Medal and Prize for outstanding contributions to theoretical physics from the Institute of Physics and the 1997 High Energy and Particle Physics Prize by the European Physical Society.

Physics with a High Intensity Proton Source at Fermilab: Project X Golden Book

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

Appel, Jeffrey; /Fermilab; Asner, David

2008-02-03

Within the next ten years the Standard Model will likely have to be modified to encompass a wide range of newly discovered phenomena, new elementary particles, new symmetries, and new dynamics. These phenomena will be revealed through experiment with high energy particle accelerators, mainly the LHC. This will represent a revolution in our understanding of nature, and will either bring us closer to an understanding of all phenomena, through existing ideas such as supersymmetry to superstrings, or will cause us to scramble to find new ideas and a new sense of direction. We are thus entering a dramatic and importantmore » time in the quest to understand the fundamental laws of nature and their role in shaping the universe. The energy scales now probed by the Tevatron, of order hundreds of GeV, will soon be subsumed by the LHC and extended up to a few TeV. We expect the unknown structure of the mysterious symmetry breaking of the Standard Model to be revealed. We will then learn the answer to a question that has a fundamental bearing upon our own existence: 'What is the origin of mass?' All modern theories of 'electroweak symmetry breaking' involve many new particles, mainly to provide a 'naturalness' rationale for the weak scale. Supersymmetry (SUSY) represents extra (fermionic) dimensions of space, leading to a doubling of the number of known elementary particles and ushering in many additional new particles and phenomena associated with the various symmetry breaking sectors. The possibility of additional bosonic dimensions of space would likewise usher in an even greater multitude of new states and new phenomena. Alternatively, any new spectroscopy may indicate new principles we have not yet anticipated, and we may see new strong forces and/or a dynamical origin of mass. The wealth of new particles, parameters, CP-phases, and other phenomena carries important implications for precision quark flavor physics experiments that are uniquely sensitive probes of new phenomena. We have already begun to see the enlargement of the Standard Model in the leptonic sector. Neutrino masses and mixing angles, which in the early 1990's were unknown, must now be incorporated into our full description of nature. In a minimal scenario of Majorana masses and mixings amongst the three known left-handed neutrinos, we see a strong hint of a new and very large mass scale, possibly associated with grand unification or the scale of quantum gravity, the Planck mass. We are not yet sure what the proper description of neutrino masses and mixing angles will be. Experiments may reveal additional unexpected particles coupled to the neutrino sector. New phenomena, such as leptonic CP-violation, will be major focal points of our expanding understanding of the lepton sector. There is much to be done with experiment to attack the issues that neutrinos now present. Already, developments in neutrino physics and the possibility of a novel source of CP-violation in the lepton sector have spawned hopes that the cosmic matter-antimatter asymmetry may be explained through leptogenesis. Neutrino physics, together with the search for new energy frontier physics, offers the possibility of experimental handles on the questions of dark matter and dark energy. Without the discovery of new particles in accelerator experiments, the telescope-based cosmological observations of the early universe would remain unexplained puzzles. The process of understanding the laws of physics in greater detail through accelerator-based high energy physics will potentially have incisive impact on our understanding of dark matter and dark energy. Precision flavor physics in both the quark and the lepton sectors offers a window on the sensitive entanglement of beyond-the-Standard-Model physics with rare processes, through quantum loop effects involving known or new states. Flavor physics offers sensitive indirect probes and may be the first place to reveal additional key components of the post-Standard Model physics. The main arenas for quark flavor physics include strange, charm and beauty, hence kaons, D-mesons, B-mesons and heavy baryons. A remarkable historical paradigm for the importance of flavor physics is the well known suppression of flavor-changing neutral currents. The analysis of the K{sub L}-K{sub S} mass difference by Gaillard and Lee, 35 years ago in the Fermilab Theory Group, led to the confirmation of the GIM mechanism and predicted the mass of the charm quark, m{sub c} {approx} 1.5 GeV, definitively and prior to its discovery. This, today, implies an astonishing constraint on SUSY models, e.g., that the down and strange squarks are mass degenerate to 1:10{sup 5}. This, in turn, has spawned a new working hypothesis called 'Minimal Flavor Violation' (MFV). But is MFV really a true principle operating in nature and, if so, where does it come from? Such questions can only be addressed in precision flavor physics experiments.« less

Elastohydrodynamic lubrication in point contact on the surfaces of particle-reinforced composite

NASA Astrophysics Data System (ADS)

Chen, Keying; Zeng, Liangcai; Wu, Zhenpeng; Zheng, Feilong

2018-04-01

Appreciable friction and serious wear are common challenges in the operation of advanced manufacturing equipment, and friction pairs may be susceptible to damage even with oil lubrication when point contact exists. In this study, a type of particle-reinforced composite material is introduced for one of the components of a heavy-load contact pair, and the performance improvement of elastohydrodynamic lubrication (EHL) is analyzed considering the rheological properties of non-Newtonian fluids. The Ree-Eyring EHL model is used considering the surface of the particle-reinforced composite, in which the film thickness includes the particle-induced elastic deformation. The problem of inclusions with different eigenstrains is solved by using Galerkin vectors. The influences of particle properties, size, burial depth, and interparticle distance on point-contact EHL are investigated. Furthermore, using several cases, the structural parameters of the particles in the composites are optimized, and an appropriate parameter range is obtained with the goal of reducing friction. Finally, the results for the EHL traction coefficient demonstrate that appropriate particle properties, size, burial depth, and interparticle distance can effectively reduce the traction coefficient in heavy-load contact.

An Integrated Higgs Force Theory

NASA Astrophysics Data System (ADS)

Colella, Antonio

2016-03-01

An Integrated Higgs force theory (IHFT) was based on 2 key requirement amplifications: a matter particle/Higgs force was one and inseparable; a matter particle/Higgs force bidirectionally condensed/evaporated from/to super force. These were basis of 5 theories: particle creation, baryogenesis, superpartner/quark decays, spontaneous symmetry breaking, and stellar black holes. Our universe's 129 matter/force particles contained 64 supersymmetric Higgs particles; 9 transient matter particles/Higgs forces decayed to 8 permanent matter particles/Higgs forces; mass was given to a matter particle by its Higgs force and gravitons; and sum of 8 Higgs force energies of 8 permanent matter particles was dark energy. An IHFT's essence is the intimate physical relationships between 8 theories. These theories are independent because physicists in one theory worked independently of physicists in the other seven. An IHFT's premise is without sacrificing their integrities, 8 independent existing theories are replaced by 8 interrelated amplified theories. Requirement amplifications provide interfaces between the 8 theories. Intimate relationships between 8 theories including the above 5 and string, Higgs forces, and Super Universe are described. The sorting category selected was F. PARTICLES AND FIELDS (e.g., F1 Higgs Physics, F10 Alternative Beyond the Standard Model Physics, F11 Dark Sector Theories and Searches, and F12 Particle Cosmology).

Topics in Theoretical Physics

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

Cohen, Andrew; Schmaltz, Martin; Katz, Emmanuel

This award supported a broadly based research effort in theoretical particle physics, including research aimed at uncovering the laws of nature at short (subatomic) and long (cosmological) distances. These theoretical developments apply to experiments in laboratories such as CERN, the facility that operates the Large Hadron Collider outside Geneva, as well as to cosmological investigations done using telescopes and satellites. The results reported here apply to physics beyond the so-called Standard Model of particle physics; physics of high energy collisions such as those observed at the Large Hadron Collider; theoretical and mathematical tools and frameworks for describing the laws ofmore » nature at short distances; cosmology and astrophysics; and analytic and computational methods to solve theories of short distance physics. Some specific research accomplishments include + Theories of the electroweak interactions, the forces that give rise to many forms of radioactive decay; + Physics of the recently discovered Higgs boson. + Models and phenomenology of dark matter, the mysterious component of the universe, that has so far been detected only by its gravitational effects. + High energy particles in astrophysics and cosmology. + Algorithmic research and Computational methods for physics of and beyond the Standard Model. + Theory and applications of relativity and its possible limitations. + Topological effects in field theory and cosmology. + Conformally invariant systems and AdS/CFT. This award also supported significant training of students and postdoctoral fellows to lead the research effort in particle theory for the coming decades. These students and fellows worked closely with other members of the group as well as theoretical and experimental colleagues throughout the physics community. Many of the research projects funded by this grant arose in response to recently obtained experimental results in the areas of particle physics and cosmology. We describe a few of these below. Relativity is founded on a symmetry property of nature called "Lorentz Invariance". Like all symmetry properties, it is essential to determine precisely how symmetric nature actually is; that is, do the laws of nature fully respect the symmetry or is there room for tiny symmetry violating effects? An important consequence of Lorentz invariance is the existence of a universal limiting velocity for all physical particles. Light travels at this limiting velocity so it is frequently referred to as simply "the speed of light", but relativity requires that ALL particles travel more slowly than this speed. Once the Higgs particle was discovered in 2012 a natural question was whether or not this particle's speed was consistent with relativity. Although the speed of the Higgs particle is not measurable directly, Cohen has shown that, if the maximal speed of the Higgs particle was not precisely the same as the speed of light, then the Higgs would have some unusual properties. In some cases the Higgs would be unstable to some unusual decay modes; in other cases the interactions of the Higgs with other particles would change the properties of these other particles in ways that could be observed in so-called cosmic rays, very energetic particles (such as photons, protons and other atomic nuclei) coming from space. Once these particles hit the upper atmosphere they produce a "shower" of particles that can be seen by ground-based instruments. If the Higgs has a maximal speed that differs even a tiny bit from the speed of light these showers would look quite different from what is observed. In this way Cohen was able to establish that the Higgs travels with a maximal speed that cannot differ from the speed of light by more than one part in a thousand-trillion. This is by far the most precisely determined property of the Higgs particle. Cohen and Schmaltz reviewed evidence from the Large Hadron Collider (LHC), a particle physics experiment operating at the CERN laboratory near Geneva, for a new particle sometimes called a W'. This evidence included certain unexpected by-products in collisions of protons at very high energy. While the evidence was not significant enough to claim a discovery, it was sufficiently intriguing that many particle theorists worked to construct explanations for this signal. Cohen and Schmaltz were able to determine that such explanations are highly constrained by previous experiments involving collisions of very energetic particles. Nevertheless they were able to construct a theory that adequately explains the LHC data and remain consistent with prior experiments. Their explanation predicts the existence of yet another new particle, called a Z', with a mass slightly greater than that of the W'. This additional particle, if it exists, should be seen as more data is collected from the LHC. Amusingly, there is one collision by-product that has already been seen by the CMS experiment at the LHC that supports the existence of this new particle; however, it is not unlikely that this single event is a so-called "background" event, that is a somewhat atypical by-product of a conventional Standard Model process. This theory for the anomalous LHC data will either be confirmed or excluded with further data-taking at the LHC. The ratio of the number of electrons produced in bottom quark decays over the number of muons produced has been measured at the LHC. This ratio is interesting because it can be predicted very precisely from a basic property of the Standard Model: lepton universality. If lepton universality is correct, the ratio of electrons to muons is predicted to be equal to 1. The first measurements of this ratio find a value different from 1 with a statistical significance of about 3 standard deviations. Schmaltz and collaborator proposed a new extension of the Standard Model which can explain the new data. In addition, Schmaltz and collaborators proposed several new measurements of ratios of decay rates which can confirm or rule out the surprising results from the earlier LHC data. The most recent and precise measurements of the cosmic microwave background from the Planck satellite, from a combination of measurements of the dark matter distribution in the universe, and from a measurement of the expansion rate of the universe today show some disagreement when interpreted in terms of the so-called LambdaCDM model. Schmaltz and collaborators proposed an alternative model to LambdaCDM in which the usual cold dark matter is replaced by a new ``dark sector". This sector consists of a cold dark matter particle which interacts with a newly postulated dark radiation component of the universe. The dark radiation can help explain the discrepancy in measurements of the expansion rate, and the dark matter interactions subtly modify the clumping of dark matter at large scales, thus potentially explaining both kinds of tensions in the data. In two publications Schmaltz described the new model and then performed a precision comparison of the predictions of the model with all currently available cosmological data. The results favor the new model at the level of three standard deviations with current data. Quantum Field Theory (QFT) is the language we use to describe quantum systems which are consistent with Einstein’s theory of Special Relativity. In particular, the requirement of Einstein’s theory that signals not travel faster than the speed of light constrains the types of interactions which particles can engage in. One consequence of relativity is that these interactions cannot preserve particle number. The stronger the interactions, the more severe the particle number violation in a given Relativistic QFT. When particle number violation is strong, it becomes very difficult to adequately parameterize the quantum wave function (which characterizes the state of a quantum system). For example, though we can formulate the QFT which describes the strong force as a set of interactions between quark and gluon particles, we have no clear idea how to express the proton state in terms of these quarks and gluons. This is because the proton, though a bound state of quarks and gluons, is not a state of a fixed number of particles due to strong interactions. Yet, understanding the proton state is very important in order to theoretically predict the reaction rates observed at the LHC in Geneva, which is a proton-proton collider. Katz has formulated a new approach to QFT, which among other things offers a way to adequately approximate the quantum wave function of a bound state at strong coupling. The approximation scheme is related to the fact that any sensible QFT (including that of the strong interactions) is at short distances approximately self-similar upon rescaling of space and time. It turns out that keeping track of the response upon this rescaling is important in efficiently parameterizing the state. Katz and collaborators have used this observation to approximate the state of the proton in toy versions of the strong force. In the late 60s Sheldon Glashow, Abdus Salam and Steven Weinberg (1979 Nobel Prize awardees) proposed a theory unifying weak and electromagnetic interaction which assumed the existence of new particles, the W and Z bosons. The W and Z bosons were eventually detected in high-energy collision in a particle accelerator at CERN, and the recent discovery of the Higgs meson at the Large Hadron Collider (LHC), always at CERN, completed the picture. However, deep theoretical considerations indicate that the theory by Glashow, Weinberg and Salam, often referred to as "the standard model" cannot be the whole story: the existence of new particles and new interactions at yet higher energies is widely anticipated. The experiments at the LHC are looking for these, while theorists, like Brower, Rebbi and collaborators, are investigating models for these new interactions. Working in a large national collaboration with access to the most powerful DOE computers Brower, Rebbi and colleagues have been using calculational techniques, similar to those successfully employed for many years to investigate the interactions among quarks in nucleons, to study theories that can describe the expected "beyond the standard model" (BSM) interactions. Their results, which include also a model for dark matter, have been published in several refereed papers in prestigious journals. Various ideas in topologically interesting field theories predict hypothetical objects such as fractional charges and Majorana excitations. However, such fascinating objects have not been seen in particle physics. Nevertheless, these objects demonstrate possible phenomena that quantum field theory can support. Pi used condensed matter physics as a laboratory to study possible realizations and observable effects of these objects predicted by quantum field theory. In recent times there has developed considerable interest among condensed matter field theorists in precisely the same geometrical and topological structures, which were first discovered in particle physics field theories. From particle physicists' point of view, this is an interesting development, since condensed matter provides an arena in which one can concretely realize particle physics ideas. Moreover, particle physicists can learn new ideas from condensed matter physics. Higgs phenomenon is precisely an important particle physics realization of condensed matter ideas. In contrast to the small distance characterizing condensed matter systems, field theory also describes large distance physics characterizing cosmology. Pi worked on various geometrical effects in the standard theory of cosmology, viz general relativity.« less

Elastic collisions of classical point particles on a finite frictionless linear track with perfectly reflecting endpoints

NASA Astrophysics Data System (ADS)

DeLuca, R.

2006-03-01

Repeated elastic collisions of point particles on a finite frictionless linear track with perfectly reflecting endpoints are considered. The problem is analysed by means of an elementary linear algebra approach. It is found that, starting with a state consisting of a projectile particle in motion at constant velocity and a target particle at rest in a fixed known position, the points at which collisions occur on track, when plotted versus progressive numerals, corresponding to the collisions themselves, show periodic patterns for a rather large choice of values of the initial position x(0) and on the mass ratio r. For certain values of these parameters, however, only regular behaviour over a large number of collisions is detected.

An LES-PBE-PDF approach for modeling particle formation in turbulent reacting flows

NASA Astrophysics Data System (ADS)

Sewerin, Fabian; Rigopoulos, Stelios

2017-10-01

Many chemical and environmental processes involve the formation of a polydispersed particulate phase in a turbulent carrier flow. Frequently, the immersed particles are characterized by an intrinsic property such as the particle size, and the distribution of this property across a sample population is taken as an indicator for the quality of the particulate product or its environmental impact. In the present article, we propose a comprehensive model and an efficient numerical solution scheme for predicting the evolution of the property distribution associated with a polydispersed particulate phase forming in a turbulent reacting flow. Here, the particulate phase is described in terms of the particle number density whose evolution in both physical and particle property space is governed by the population balance equation (PBE). Based on the concept of large eddy simulation (LES), we augment the existing LES-transported probability density function (PDF) approach for fluid phase scalars by the particle number density and obtain a modeled evolution equation for the filtered PDF associated with the instantaneous fluid composition and particle property distribution. This LES-PBE-PDF approach allows us to predict the LES-filtered fluid composition and particle property distribution at each spatial location and point in time without any restriction on the chemical or particle formation kinetics. In view of a numerical solution, we apply the method of Eulerian stochastic fields, invoking an explicit adaptive grid technique in order to discretize the stochastic field equation for the number density in particle property space. In this way, sharp moving features of the particle property distribution can be accurately resolved at a significantly reduced computational cost. As a test case, we consider the condensation of an aerosol in a developed turbulent mixing layer. Our investigation not only demonstrates the predictive capabilities of the LES-PBE-PDF model but also indicates the computational efficiency of the numerical solution scheme.

Gastroretentive extended-release floating granules prepared using a novel fluidized hot melt granulation (FHMG) technique.

PubMed

Zhai, H; Jones, D S; McCoy, C P; Madi, A M; Tian, Y; Andrews, G P

2014-10-06

The objective of this work was to investigate the feasibility of using a novel granulation technique, namely, fluidized hot melt granulation (FHMG), to prepare gastroretentive extended-release floating granules. In this study we have utilized FHMG, a solvent free process in which granulation is achieved with the aid of low melting point materials, using Compritol 888 ATO and Gelucire 50/13 as meltable binders, in place of conventional liquid binders. The physicochemical properties, morphology, floating properties, and drug release of the manufactured granules were investigated. Granules prepared by this method were spherical in shape and showed good flowability. The floating granules exhibited sustained release exceeding 10 h. Granule buoyancy (floating time and strength) and drug release properties were significantly influenced by formulation variables such as excipient type and concentration, and the physical characteristics (particle size, hydrophilicity) of the excipients. Drug release rate was increased by increasing the concentration of hydroxypropyl cellulose (HPC) and Gelucire 50/13, or by decreasing the particle size of HPC. Floating strength was improved through the incorporation of sodium bicarbonate and citric acid. Furthermore, floating strength was influenced by the concentration of HPC within the formulation. Granules prepared in this way show good physical characteristics, floating ability, and drug release properties when placed in simulated gastric fluid. Moreover, the drug release and floating properties can be controlled by modification of the ratio or physical characteristics of the excipients used in the formulation.

Fermilab | About Fermilab | Photo and Video Gallery

Science.gov Websites

LHC Dark matter and dark energy ADMX Muons More fundamental particles and forces Theory Scientific society Particle Physics 101 Science of matter, energy, space and time How particle physics discovery rarely interact with matter. thumb Med-Res Hi-Res A view of Fermilab's MINERvA detector with the MINOS

Meta-Analysis inside and outside Particle Physics: Two Traditions That Should Converge?

ERIC Educational Resources Information Center

Baker, Rose D.; Jackson, Dan

2013-01-01

The use of meta-analysis in medicine and epidemiology really took off in the 1970s. However, in high-energy physics, the Particle Data Group has been carrying out meta-analyses of measurements of particle masses and other properties since 1957. Curiously, there has been virtually no interaction between those working inside and outside particle…

Nuclear physics in particle therapy: a review

NASA Astrophysics Data System (ADS)

Durante, Marco; Paganetti, Harald

2016-09-01

Charged particle therapy has been largely driven and influenced by nuclear physics. The increase in energy deposition density along the ion path in the body allows reducing the dose to normal tissues during radiotherapy compared to photons. Clinical results of particle therapy support the physical rationale for this treatment, but the method remains controversial because of the high cost and of the lack of comparative clinical trials proving the benefit compared to x-rays. Research in applied nuclear physics, including nuclear interactions, dosimetry, image guidance, range verification, novel accelerators and beam delivery technologies, can significantly improve the clinical outcome in particle therapy. Measurements of fragmentation cross-sections, including those for the production of positron-emitting fragments, and attenuation curves are needed for tuning Monte Carlo codes, whose use in clinical environments is rapidly increasing thanks to fast calculation methods. Existing cross sections and codes are indeed not very accurate in the energy and target regions of interest for particle therapy. These measurements are especially urgent for new ions to be used in therapy, such as helium. Furthermore, nuclear physics hardware developments are frequently finding applications in ion therapy due to similar requirements concerning sensors and real-time data processing. In this review we will briefly describe the physics bases, and concentrate on the open issues.

Nuclear physics in particle therapy: a review.

PubMed

Durante, Marco; Paganetti, Harald

2016-09-01

Charged particle therapy has been largely driven and influenced by nuclear physics. The increase in energy deposition density along the ion path in the body allows reducing the dose to normal tissues during radiotherapy compared to photons. Clinical results of particle therapy support the physical rationale for this treatment, but the method remains controversial because of the high cost and of the lack of comparative clinical trials proving the benefit compared to x-rays. Research in applied nuclear physics, including nuclear interactions, dosimetry, image guidance, range verification, novel accelerators and beam delivery technologies, can significantly improve the clinical outcome in particle therapy. Measurements of fragmentation cross-sections, including those for the production of positron-emitting fragments, and attenuation curves are needed for tuning Monte Carlo codes, whose use in clinical environments is rapidly increasing thanks to fast calculation methods. Existing cross sections and codes are indeed not very accurate in the energy and target regions of interest for particle therapy. These measurements are especially urgent for new ions to be used in therapy, such as helium. Furthermore, nuclear physics hardware developments are frequently finding applications in ion therapy due to similar requirements concerning sensors and real-time data processing. In this review we will briefly describe the physics bases, and concentrate on the open issues.

CERN launches high-school internship programme

NASA Astrophysics Data System (ADS)

Johnston, Hamish

2017-07-01

The CERN particle-physics lab has hosted 22 high-school students from Hungary in a pilot programme designed to show teenagers how science, technology, engineering and mathematics is used at the particle-physics lab.

Quarked! - Adventures in Particle Physics Education

NASA Astrophysics Data System (ADS)

MacDonald, Teresa; Bean, Alice

2009-01-01

Particle physics is a subject that can send shivers down the spines of students and educators alike-with visions of long mathematical equations and inscrutable ideas. This perception, along with a full curriculum, often leaves this topic the road less traveled until the latter years of school. Particle physics, including quarks, is typically not introduced until high school or university.1,2 Many of these concepts can be made accessible to younger students when presented in a fun and engaging way. Informal science institutions are in an ideal position to communicate new and challenging science topics in engaging and innovative ways and offer a variety of educational enrichment experiences for students that support and enhance science learning.3 Quarked!™ Adventures in the Subatomic Universe, a National Science Foundation EPSCoR-funded particle physics education program, provides classroom programs and online educational resources.

Detectors for Particle Radiation

NASA Astrophysics Data System (ADS)

Kleinknecht, Konrad

1999-01-01

This textbook provides a clear, concise and comprehensive review of the physical principles behind the devices used to detect charged particles and gamma rays, and the construction and performance of these many different types of detectors. Detectors for high-energy particles and radiation are used in many areas of science, especially particle physics and nuclear physics experiments, nuclear medicine, cosmic ray measurements, space sciences and geological exploration. This second edition includes all the latest developments in detector technology, including several new chapters covering micro-strip gas chambers, silicion strip detectors and CCDs, scintillating fibers, shower detectors using noble liquid gases, and compensating calorimeters for hadronic showers. This well-illustrated textbook contains examples from the many areas in science in which these detectors are used. It provides both a coursebook for students in physics, and a useful introduction for researchers in other fields.

Nuclear and particle physics, astrophysics and cosmology (NPAC) capability review

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

Redondo, Antonio

2010-01-01

The present document represents a summary self-assessment of the status of the Nuclear and Particle Physics, Astrophysics and Cosmology (NPAC) capability across Los Alamos National Laboratory (LANL). For the purpose of this review, we have divided the capability into four theme areas: Nuclear Physics, Particle Physics, Astrophysics and Cosmology, and Applied Physics. For each theme area we have given a general but brief description of the activities under the area, a list of the Laboratory divisions involved in the work, connections to the goals and mission of the Laboratory, a brief description of progress over the last three years, ourmore » opinion of the overall status of the theme area, and challenges and issues.« less

Hexagonalization of correlation functions II: two-particle contributions

NASA Astrophysics Data System (ADS)

Fleury, Thiago; Komatsu, Shota

2018-02-01

In this work, we compute one-loop planar five-point functions in N=4 super-Yang-Mills using integrability. As in the previous work, we decompose the correlation functions into hexagon form factors and glue them using the weight factors which depend on the cross-ratios. The main new ingredient in the computation, as compared to the four-point functions studied in the previous paper, is the two-particle mirror contribution. We develop techniques to evaluate it and find agreement with the perturbative results in all the cases we analyzed. In addition, we consider next-to-extremal four-point functions, which are known to be protected, and show that the sum of one-particle and two-particle contributions at one loop adds up to zero as expected. The tools developed in this work would be useful for computing higher-particle contributions which would be relevant for more complicated quantities such as higher-loop corrections and non-planar correlators.

Evidence that Hsc70 Is Associated with Cucumber Necrosis Virus Particles and Plays a Role in Particle Disassembly

PubMed Central

Alam, Syed Benazir

2016-01-01

ABSTRACT Uncoating of a virus particle to expose its nucleic acid is a critical aspect of the viral multiplication cycle, as it is essential for the establishment of infection. In the present study, we investigated the role of plant HSP70 homologs in the uncoating process of Cucumber necrosis virus (CNV), a nonenveloped positive-sense single-stranded RNA [(+)ssRNA] virus having a T=3 icosahedral capsid. We have found through Western blot analysis and mass spectrometry that the HSP70 homolog Hsc70-2 copurifies with CNV particles. Virus overlay and immunogold labeling assays suggest that Hsc70-2 is physically bound to virions. Furthermore, trypsin digestion profiles suggest that the bound Hsc70-2 is partially protected by the virus, indicating an intimate association with particles. In investigating a possible role of Hsc70-2 in particle disassembly, we showed that particles incubated with Hsp70/Hsc70 antibody produce fewer local lesions than those incubated with prebleed control antibody on Chenopodium quinoa. In conjunction, CNV virions purified using CsCl and having undetectable amounts of Hsc70-2 produce fewer local lesions. We also have found that plants with elevated levels of HSP70/Hsc70 produce higher numbers of local lesions following CNV inoculation. Finally, incubation of recombinant Nicotiana benthamiana Hsc70-2 with virus particles in vitro leads to conformational changes or partial disassembly of capsids as determined by transmission electron microscopy, and particles are more sensitive to chymotrypsin digestion. This is the first report suggesting that a cellular Hsc70 chaperone is involved in disassembly of a plant virus. IMPORTANCE Virus particles must disassemble and release their nucleic acid in order to establish infection in a cell. Despite the importance of disassembly in the ability of a virus to infect its host, little is known about this process, especially in the case of nonenveloped spherical RNA viruses. Previous work has shown that host HSP70 homologs play multiple roles in the CNV infection cycle. We therefore examined the potential role of these cellular components in the CNV disassembly process. We show that the HSP70 family member Hsc70-2 is physically associated with CNV virions and that HSP70 antibody reduces the ability of CNV to establish infection. Statistically significantly fewer lesions are produced when virions having undetectable HSc70-2 are used as an inoculum. Finally incubation of Hsc70-2 with CNV particles results in conformational changes in particles. Taken together, our data point to an important role of the host factor Hsc70-2 in CNV disassembly. PMID:27807229

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

Parker, Scott; Chen, Yang

This is the Final Technical Report for University of Colorado's portion of the SciDAC project 'Center for Gyrokinetic Particle Simulation of Turbulent Transport.' This is funded as a multi-institutional SciDAC Center and W.W. Lee at the Princeton Plasma Physics Laboratory is the lead Principal Investigator. Scott Parker is the local Principal Investigator for University of Colorado and Yang Chen is a Co-Principal Investigator. This is Cooperative Agreement DE-FC02-05ER54816. Research personnel include Yang Chen (Senior Research Associate), Jianying Lang (Graduate Research Associate, Ph.D. Physics Student) and Scott Parker (Associate Professor). Research includes core microturbulence studies of NSTX, simulation of trapped electronmore » modes, development of efficient particle-continuum hybrid methods and particle convergence studies of electron temperature gradient driven turbulence simulations. Recently, the particle-continuum method has been extended to five-dimensions in GEM. We find that actually a simple method works quite well for the Cyclone base case with either fully kinetic or adiabatic electrons. Particles are deposited on a 5D phase-space grid using nearest-grid-point interpolation. Then, the value of delta-f is reset, but not the particle's trajectory. This has the effect of occasionally averaging delta-f of nearby (in the phase space) particles. We are currently trying to estimate the dissipation (or effective collision operator). We have been using GEM to study turbulence and transport in NSTX with realistic equilibrium density and temperature profiles, including impurities, magnetic geometry and ExB shear flow. Greg Rewoldt, PPPL, has developed a TRANSP interface for GEM that specifies the equilibrium profiles and parameters needed to run realistic NSTX cases. Results were reported at the American Physical Society - Division of Plasma Physics, and we are currently running convergence studies to ensure physical results. We are also studying the effect of parallel shear flows, which can be quite strong in NSTX. Recent long-time simulations of electron temperature gradient driven turbulence, show that zonal flows slowly grow algebraically via the Rosenbluth-Hinton random walk mechanism. Eventually, the zonal flow gets to a level where it shear suppresses the turbulence. We have demonstrated this behavior with Cyclone base-case parameters, except with a 30% lower temperature gradient. We can demonstrate the same phenomena at higher gradients, but so far, have been unable to get a converged result at the higher temperature gradient. We find that electron ion collisions cause the zonal flows to grow at a slower rate and results in a higher heat flux. So, far all ETG simulations that come to a quasi-steady state show continued build up of zonal flow, see it appears to be a universal phenomena (for ETG). Linear and nonlinear simulations of Collisional and Collisionless trapped electron modes are underway. We find that zonal flow is typically important. We can, however, reproduce the Tannert and Jenko result (that zonal flow is unimportant) using their parameters with the electron temperature three times the ion temperature. For a typical weak gradient core value of density gradient and no temperature gradient, the CTEM is dominant. However, for a steeper density gradient (and still no temperature gradient), representative of the edge, higher k drift-waves are dominant. For the weaker density gradient core case, nonlinear simulations using GEM are routine. For the steeper gradient edge case, the nonlinear fluctuations are very high and a stationary state has not been obtained. This provides motivation for the particle-continuum algorithm. We also note that more physics, e.g. profile variation and equilibrium ExB shear flow should be significantly stabilizing, making such simulations feasible using standard delta-f techniques. This research is ongoing.« less

Particle Physics at the Cosmic, Intensity, and Energy Frontiers

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

Essig, Rouven

Major efforts at the Intensity, Cosmic, and Energy frontiers of particle physics are rapidly furthering our understanding of the fundamental constituents of Nature and their interactions. The overall objectives of this research project are (1) to interpret and develop the theoretical implications of the data collected at these frontiers and (2) to provide the theoretical motivation, basis, and ideas for new experiments and for new analyses of experimental data. Within the Intensity Frontier, an experimental search for a new force mediated by a GeV-scale gauge boson will be carried out with the $A'$ Experiment (APEX) and the Heavy Photon Searchmore » (HPS), both at Jefferson Laboratory. Within the Cosmic Frontier, contributions are planned to the search for dark matter particles with the Fermi Gamma-ray Space Telescope and other instruments. A detailed exploration will also be performed of new direct detection strategies for dark matter particles with sub-GeV masses to facilitate the development of new experiments. In addition, the theoretical implications of existing and future dark matter-related anomalies will be examined. Within the Energy Frontier, the implications of the data from the Large Hadron Collider will be investigated. Novel search strategies will be developed to aid the search for new phenomena not described by the Standard Model of particle physics. By combining insights from all three particle physics frontiers, this research aims to increase our understanding of fundamental particle physics.« less

News Particle Physics: ATLAS unveils mural at CERN Prize: Corti Trust invites essay entries Astrophysics: CERN holds cosmic-ray conference Researchers in Residence: Lord Winston returns to school Music: ATLAS scientists record physics music Conference: Champagne flows at Reims event Competition: Students triumph at physics olympiad Teaching: Physics proves popular in Japanese schools Forthcoming Events

NASA Astrophysics Data System (ADS)

2011-01-01

Particle Physics: ATLAS unveils mural at CERN Prize: Corti Trust invites essay entries Astrophysics: CERN holds cosmic-ray conference Researchers in Residence: Lord Winston returns to school Music: ATLAS scientists record physics music Conference: Champagne flows at Reims event Competition: Students triumph at physics olympiad Teaching: Physics proves popular in Japanese schools Forthcoming Events

Chiral anomaly, Berry phase, and chiral kinetic theory from worldlines in quantum field theory

NASA Astrophysics Data System (ADS)

Mueller, Niklas; Venugopalan, Raju

2018-03-01

In previous work, we outlined a worldline framework that can be used for systematic computations of the chiral magnetic effect (CME) in ultrarelativistic heavy-ion collisions. Towards this end, we first expressed the real part of the fermion determinant in the QCD effective action as a supersymmetric worldline action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. The chiral anomaly, in contrast, arises from the phase of the fermion determinant. Remarkably, the latter too can be expressed as a point particle worldline path integral, which can be employed to derive the anomalous axial vector current. We will show here how Berry's phase can be obtained in a consistent nonrelativistic adiabatic limit of the real part of the fermion determinant. Our work provides a general first principles demonstration that the topology of Berry's phase is distinct from that of the chiral anomaly confirming prior arguments by Fujikawa in specific contexts. This suggests that chiral kinetic treatments of the CME in heavy-ion collisions that include Berry's phase alone are incomplete. We outline the elements of a worldline covariant relativistic chiral kinetic theory that captures the physics of how the chiral current is modified by many-body scattering and topological fluctuations.

Physical characterization of aerosol particles during the Chinese New Year’s firework events

NASA Astrophysics Data System (ADS)

Zhang, Min; Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Wang, Tao; Yang, Xin; Gong, Youguo; Geng, Fuhai; Chen, Changhong

2010-12-01

Measurements for particles 10 nm to 10 μm were taken using a Wide-range Particle Spectrometer during the Chinese New Year (CNY) celebrations in 2009 in Shanghai, China. These celebrations provided an opportunity to study the number concentration and size distribution of particles in an especial atmospheric pollution situation due to firework displays. The firework activities had a clear contribution to the number concentration of small accumulation mode particles (100-500 nm) and PM 1 mass concentration, with a maximum total number concentration of 3.8 × 10 4 cm -3. A clear shift of particles from nucleation and Aitken mode to small accumulation mode was observed at the peak of the CNY firework event, which can be explained by reduced atmospheric lifetimes of smaller particles via the concept of the coagulation sink. High particle density (2.7 g cm -3) was identified as being particularly characteristic of the firework aerosols. Recalculated fine particles PM 1 exhibited on average above 150 μg m -3 for more than 12 hours, which was a health risk to susceptible individuals. Integral physical parameters of firework aerosols were calculated for understanding their physical properties and further model simulation.

Fluorescence labeling of colloidal core-shell particles with defined isoelectric points for in vitro studies.

PubMed

Daberkow, Timo; Meder, Fabian; Treccani, Laura; Schowalter, Marco; Rosenauer, Andreas; Rezwan, Kurosch

2012-02-01

In the light of in vitro nanotoxicological studies fluorescence labeling has become standard for particle localization within the cell environment. However, fluorescent labeling is also known to significantly alter the particle surface chemistry and therefore potentially affect the outcome of cell studies. Hence, fluorescent labeling is ideally carried out without changing, for example, the isoelectric point. A simple and straightforward method for obtaining fluorescently labeled spherical metal oxide particles with well-defined isoelectric points and a narrow size distribution is presented in this study. Spherical amorphous silica (SiO2, 161 nm diameter) particles were used as the substrate material and were coated with silica, alumina (Al2O3), titania (TiO2), or zirconia (ZrO2) using sol-gel chemistry. Fluorescent labeling was achieved by directly embedding rhodamine 6G dye in the coating matrix without affecting the isoelectric point of the metal oxide coatings. The coating quality was confirmed by high resolution transmission electron microscopy, energy filtered transmission electron microscopy and electrochemical characterization. The coatings were proven to be stable for at least 240 h under different pH conditions. The well-defined fluorescent particles can be directly used for biomedical investigations, e.g. elucidation of particle-cell interactions in vitro. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

FMR thermomagnetic studies up to 900 C of lunar soils and potential magnetic analogues. [Ferromagnetic Resonance studies

NASA Technical Reports Server (NTRS)

Morris, R. V.; Gibbons, R. V.; Hoerz, F.

1975-01-01

Using a recently developed furnace, ferromagnetic resonance (FMR) thermomagnetic studies up to 900 C were employed to measure the Curie points of the superparamagnetic (SP) and single domain (SD) particles in lunar soils and potential magnetic analogue materials. Based on measured Curie points of 775 C, the SP and SD particles in lunar soils 10084-853, 12070-29, 14161-46, and 67010-4 are essentially pure metallic Fe. Synthetic and terrestrial samples containing magnetite, titanomaghemites, and magnetite-like particles have measured Curie points below 600 C are thus not magnetic analogues of lunar soils.

Characterizing physical properties and heterogeneous chemistry of single particles in air using optical trapping-Raman spectroscopy

NASA Astrophysics Data System (ADS)

Gong, Z.; Wang, C.; Pan, Y. L.; Videen, G.

2017-12-01

Heterogeneous reactions of solid particles in a gaseous environment are of increasing interest; however, most of the heterogeneous chemistry studies of airborne solids were conducted on particle ensembles. A close examination on the heterogeneous chemistry between single particles and gaseous-environment species is the key to elucidate the fundamental mechanisms of hydroscopic growth, cloud nuclei condensation, secondary aerosol formation, etc., and reduce the uncertainty of models in radiative forcing, climate change, and atmospheric chemistry. We demonstrate an optical trapping-Raman spectroscopy (OT-RS) system to study the heterogeneous chemistry of the solid particles in air at single-particle level. Compared to other single-particle techniques, optical trapping offers a non-invasive, flexible, and stable method to isolate single solid particle from substrates. Benefited from two counter-propagating hollow beams, the optical trapping configuration is adaptive to trap a variety of particles with different materials from inorganic substitution (carbon nanotubes, silica, etc.) to organic, dye-doped polymers and bioaerosols (spores, pollen, etc.), with different optical properties from transparent to strongly absorbing, with different sizes from sub-micrometers to tens of microns, or with distinct morphologies from loosely packed nanotubes to microspheres and irregular pollen grains. The particles in the optical trap may stay unchanged, surface degraded, or optically fragmented according to different laser intensity, and their physical and chemical properties are characterized by the Raman spectra and imaging system simultaneously. The Raman spectra is able to distinguish the chemical compositions of different particles, while the synchronized imaging system can resolve their physical properties (sizes, shapes, morphologies, etc.). The temporal behavior of the trapped particles also can be monitored by the OT-RS system at an indefinite time with a resolution from 10 ms to 5 min, which can be further applied to monitor the dynamics of heterogeneous reactions. The OT-RS system provides a flexible method to characterize and monitor the physical properties and heterogeneous chemistry of optically trapped solid particles in gaseous environment at single-particle level.

Particle Physics, 2nd Edition

NASA Astrophysics Data System (ADS)

Martin, B. R.; Shaw, G.

1998-01-01

Particle Physics, Second Edition is a concise and lucid account of the fundamental constituents of matter. The standard model of particle physics is developed carefully and systematically, without heavy mathematical formalism, to make this stimulating subject accessible to undergraduate students. Throughout, the emphasis is on the interpretation of experimental data in terms of the basic properties of quarks and leptons, and extensive use is made of symmetry principles and Feynman diagrams, which are introduced early in the book. The Second Edition brings the book fully up to date, including the discovery of the top quark and the search for the Higgs boson. A final short chapter is devoted to the continuing search for new physics beyond the standard model. Particle Physics, Second Edition features: * A carefully structured and written text to help students understand this exciting and demanding subject. * Many worked examples and problems to aid student learning. Hints for solving the problems are given in an Appendix. * Optional "starred" sections and appendices, containing more specialised and advanced material for the more ambitious reader.

Decoupling the Role of Inertia and Gravity on Particle Dispersion

NASA Technical Reports Server (NTRS)

Rogers, Chris; Squires, Kyle

1996-01-01

Turbulent gas flows laden with small, dense particles are encountered in a wide number of important applications in both industrial settings and aerodynamics applications. Particle interactions with the underlying turbulent flow are exceedingly complex and, consequently, difficult to accurately model. The difficulty arises primarily due to the fact that response of a particle to the local environment is dictated by turbulence properties in the reference frame moving with the particle (particle-Lagrangian). The particle-Lagrangian reference frame is in turn dependent upon the particle relaxation time (time constant) as well as gravitational drift. The combination of inertial and gravitational effects in this frame complicates our ability to accurately predict particle-laden flows since measurements in the particle-Lagrangian reference frame are difficult to obtain. Therefore, in this work we will examine separately the effects of inertia and gravitational drift on particle dispersion through a combination of physical and numerical experiments. In this study, particle-Lagrangian measurements will be obtained in physical experiments using stereo image velocimetry. Gravitational drift will be varied in the variable-g environments of the NASA DC-9 and in the zero-g environment at the drop tower at NASA-Lewis. Direct numerical simulations will be used to corroborate the measurements from the variable-g experiments. We expect that this work will generate new insight into the underlying physics of particle dispersion and will, in turn, lead to more accurate models of particle transport in turbulent flows.

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

Quigg, C.

The author sketches some pressing questions in several active areas of particle physics and outline the challenges they present for the design and operation of detectors. His assignment at the 1999 ICFA Instrumentation School is to survey some current developments in particle physics, and to describe the kinds of experiments they would like to do in the near future and illustrate the demands their desires place on detectors and data analysis. Like any active science, particle physics is in a state of continual renewal. Many of the subjects that seem most fascinating and most promising today simply did not existmore » as recently as twenty-five years ago. Other topics that have preoccupied physicists for many years have been reshaped by recent discoveries and insights, and transformed by new techniques in accelerator science and detector technology. To provide some context for the courses and laboratories at this school, he has chosen three topics that are of high scientific interest, and that place very different demands on instrumental techniques. He hopes that you will begin to see the breadth of opportunities in particle physics, and that you will also look beyond the domain of particle physics for opportunities to apply the lessons you learn here in Istanbul.« less

Chemically Reacting One-Dimensional Gas-Particle Flows

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Penny, M. M.

1975-01-01

The governing equations for the one-dimensional flow of a gas-particle system are discussed. Gas-particle effects are coupled via the system momentum and energy equations with the gas assumed to be chemically frozen or in chemical equilibrium. A computer code for calculating the one-dimensional flow of a gas-particle system is discussed and a user's input guide presented. The computer code provides for the expansion of the gas-particle system from a specified starting velocity and nozzle inlet geometry. Though general in nature, the final output of the code is a startline for initiating the solution of a supersonic gas-particle system in rocket nozzles. The startline includes gasdynamic data defining gaseous startline points from the nozzle centerline to the nozzle wall and particle properties at points along the gaseous startline.

Particle physics meets cosmology - The search for decaying neutrinos

NASA Technical Reports Server (NTRS)

Henry, R. C.

1982-01-01

The fundamental physical implications of the possible detection of massive neutrinos are discussed, with an emphasis on the Grand Unified Theories (GUTs) of matter. The Newtonian and general-relativistic pictures of the fundamental forces are compared, and the reduction of electromagnetic and weak forces to one force in the GUTs is explained. The cosmological consequences of the curved-spacetime gravitation concept are considered. Quarks, leptons, and neutrinos are characterized in a general treatment of elementary quantum mechanics. The universe is described in terms of quantized fields, the noninteractive 'particle' fields and the force fields, and cosmology becomes the study of the interaction of gravitation with the other fields, of the 'freezing out' of successive fields with the expansion and cooling of the universe. While the visible universe is the result of the clustering of the quark and electron fields, the distribution of the large number of quanta in neutrino field, like the mass of the neutrino, are unknown. Cosmological models which attribute anomalies in the observed motions of galaxies and stars to clusters or shells of massive neutrinos are shown to be consistent with a small but nonzero neutrino mass and a universe near the open/closed transition point, but direct detection of the presence of massive neutrinos by the UV emission of their decay is required to verify these hypotheses.

The ideal neutrino beams

NASA Astrophysics Data System (ADS)

Lindroos, Mats

2009-06-01

The advance in neutrino oscillation physics is driven by the availability of well characterized and high flux neutrino beams. The three present options for the next generation neutrino oscillation facility are super beams, neutrino factories and beta-beams. A super-beam is a very high intensity classical neutrino beam generated by protons impinging on a target where the neutrinos are generated by the secondary particles decaying in a tunnel down streams of the target. In a neutrino factory the neutrinos are generated from muons decaying in a storage ring with long straight sections pointing towards the detectors. In a beta-beam the neutrinos are also originating from decay in a storage ring but the decaying particles are radioactive ions rather than muons. I will in this presentation review the three options and discuss the pros and cons of each. The present joint design effort for a future high intensity neutrino oscillation in Europe within a common EU supported design study, EURONU, will also be presented. The design study will explore the physics reach, the detectors, the feasibility, the safety issues and the cost for each of the options so that the the community can take a decision on what to build when the facilities presently under exploitation and construction have to be replaced.

Photons, photon jets, and dark photons at 750 GeV and beyond.

PubMed

Dasgupta, Basudeb; Kopp, Joachim; Schwaller, Pedro

2016-01-01

In new physics searches involving photons at the LHC, one challenge is to distinguish scenarios with isolated photons from models leading to "photon jets". For instance, in the context of the 750 GeV diphoton excess, it was pointed out that a true diphoton resonance [Formula: see text] can be mimicked by a process of the form [Formula: see text], where S is a new scalar with a mass of 750 GeV and a is a light pseudoscalar decaying to two collinear photons. Photon jets can be distinguished from isolated photons by exploiting the fact that a large fraction of photons convert to an [Formula: see text] pair inside the inner detector. In this note, we quantify this discrimination power, and we study how the sensitivity of future searches differs for photon jets compared to isolated photons. We also investigate how our results depend on the lifetime of the particle(s) decaying to the photon jet. Finally, we discuss the extension to [Formula: see text], where there are no photons at all but the dark photon [Formula: see text] decays to [Formula: see text] pairs. Our results will be useful in future studies of the putative 750 GeV signal, but also more generally in any new physics search involving hard photons.

Making the universe safe for historians: Time travel and the laws of physics

NASA Astrophysics Data System (ADS)

Woodward, James F.

1995-02-01

The study of the hypothetical activities of arbitrarily advanced cultures, particularly in the area of space and time travel, as a means of investigating fundamental issues in physics is briefly discussed. Hawking's chronology protection conjecture as it applies to wormhole spacetimes is considered. The nature of time, especially regarding the viability of time travel, as it appears in several “interpretations” of quantum mechanics is investigated. A conjecture on the plausibility of theories of reality that admit relativistically invariant interactions and irreducibly stochastic processes is advanced. A transient inertial reaction effect that makes it technically feasible, fleetingly, to induce large concentrations of negative mass-energy is presented and discussed in the context of macroscopic wormhole formation. Other candidates for chronology protection are examined. It is pointed out that if the strong version of Mach's principle (the gravitational induction of mass) is correct, then wormhole formation employing negative mass-energy is impossible. But if the bare masses of elementary particles are large, finite and negative, as is suggested by a heuristic general relativistic model of elementary particles, then, using the transient effect, it is technically feasible to trigger a non-linear process that may lead to macroscopic wormhole formation. Such wormholes need not be destroyed by the Hawking protection mechanism.

Geometrically unrestricted, topologically constrained control of liquid crystal defects using simultaneous holonomic magnetic and holographic optical manipulation.

PubMed

Varney, Michael C M; Jenness, Nathan J; Smalyukh, Ivan I

2014-02-01

Despite the recent progress in physical control and manipulation of various condensed matter, atomic, and particle systems, including individual atoms and photons, our ability to control topological defects remains limited. Recently, controlled generation, spatial translation, and stretching of topological point and line defects have been achieved using laser tweezers and liquid crystals as model defect-hosting systems. However, many modes of manipulation remain hindered by limitations inherent to optical trapping. To overcome some of these limitations, we integrate holographic optical tweezers with a magnetic manipulation system, which enables fully holonomic manipulation of defects by means of optically and magnetically controllable colloids used as "handles" to transfer forces and torques to various liquid crystal defects. These colloidal handles are magnetically rotated around determined axes and are optically translated along three-dimensional pathways while mechanically attached to defects, which, combined with inducing spatially localized nematic-isotropic phase transitions, allow for geometrically unrestricted control of defects, including previously unrealized modes of noncontact manipulation, such as the twisting of disclination clusters. These manipulation capabilities may allow for probing topological constraints and the nature of defects in unprecedented ways, providing the foundation for a tabletop laboratory to expand our understanding of the role defects play in fields ranging from subatomic particle physics to early-universe cosmology.