Tamper resistant magnetic stripes

DOEpatents

Naylor, Richard Brian; Sharp, Donald J.

1999-01-01

This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.

Reinterpretation of Students' Ideas When Reasoning about Particle Model Illustrations

ERIC Educational Resources Information Center

Langbeheim, Elon

2015-01-01

The article, "Using Animations in Identifying General Chemistry Students' Misconceptions and Evaluating Their Knowledge Transfer Relating to Particle Position in Physical Changes" (Smith and Villarreal, 2015), reports that a substantial proportion of undergraduate students expressed misconceived ideas regarding the motion of particles in…

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.

Phase-factor-dependent symmetries and quantum phases in a three-level cavity QED system.

PubMed

Fan, Jingtao; Yu, Lixian; Chen, Gang; Jia, Suotang

2016-05-03

Unlike conventional two-level particles, three-level particles may support some unitary-invariant phase factors when they interact coherently with a single-mode quantized light field. To gain a better understanding of light-matter interaction, it is thus necessary to explore the phase-factor-dependent physics in such a system. In this report, we consider the collective interaction between degenerate V-type three-level particles and a single-mode quantized light field, whose different components are labeled by different phase factors. We mainly establish an important relation between the phase factors and the symmetry or symmetry-broken physics. Specifically, we find that the phase factors affect dramatically the system symmetry. When these symmetries are breaking separately, rich quantum phases emerge. Finally, we propose a possible scheme to experimentally probe the predicted physics of our model. Our work provides a way to explore phase-factor-induced nontrivial physics by introducing additional particle levels.

Particle Physics in the Sky and Astrophysics Underground: Connecting the Universe's Largest and Smallest Scales

NASA Astrophysics Data System (ADS)

Swanson, Molly E. C.

2008-08-01

Particles have tremendous potential as astronomical messengers, and conversely, studying the universe as a whole also teaches us about particle physics. This thesis encompasses both of these research directions. Many models predict a diffuse flux of high energy neutrinos from active galactic nuclei and other astrophysical sources. The "Astrophysics Underground" portion of this thesis describes a search for this neutrino flux performed by looking for very high energy upward-going muons using the Super-K detector. In addition to using particles to do astronomy, we can also use the universe itself as a particle physics lab. The "Particle Physics in the Sky" portion of this thesis focuses on extracting cosmological information from galaxy surveys. To overcome technical challenges faced by the latest galaxy surveys, we produced a comprehensive upgrade to mangle, a software package that processes the angular masks defining the survey area on the sky. We added dramatically faster algorithms and new useful features that are necessary for managing complex masks of current and next-generation galaxy surveys. With this software in hand, we utilized SDSS data to investigate the relation between galaxies and dark matter by studying relative bias, i.e., the relation between different types of galaxies. Separating galaxies by their luminosities and colors reveals a complicated picture: red galaxies are clustered more strongly than blue galaxies, with both the brightest and the faintest red galaxies showing the strongest clustering. Furthermore, red and blue galaxies tend to occupy different regions of space. In order to make precise measurements from the next generation of galaxy surveys, it will be essential to account for this complexity.

Using integral dispersion relations to extend the LHC reach for new physics

NASA Astrophysics Data System (ADS)

Denton, Peter B.; Weiler, Thomas J.

2014-02-01

Many models of electroweak symmetry breaking predict new particles with masses at or just beyond LHC energies. Even if these particles are too massive to be produced on-shell at the LHC, it may be possible to see evidence of their existence through the use of integral dispersion relations (IDRs). Making use of Cauchy's integral formula and the analyticity of the scattering amplitude, IDRs are sensitive in principle to changes in the cross section at arbitrarily large energies. We investigate some models of new physics. We find that a sudden, order-one increase in the cross section above new particle mass thresholds can be inferred well below the threshold energy. On the other hand, for two more physical models of particle production, we show that the reach in energy and the signal strength of the IDR technique is greatly reduced. The peak sensitivity for the IDR technique is shown to occur when the new particle masses are near the machine energy, an energy where direct production of new particles is kinematically disallowed, phase-space suppressed, or, if applicable, suppressed by the soft parton distribution functions. Thus, IDRs do extend the reach of the LHC, but only to a window around Mχ˜√sLHC .

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

History of the Bevatron

ScienceCinema

LBNL

2017-12-09

This 1993 documentary chronicles the Bevatron at Berkeley Lab. During its operation from 1954 until 1993, the Bevatron was among the world's leading particle accelerators, and during the 1950s and ... This 1993 documentary chronicles the Bevatron at Berkeley Lab. During its operation from 1954 until 1993, the Bevatron was among the world's leading particle accelerators, and during the 1950s and 1960s, four Nobel Prizes were awarded for work conducted in whole or in part there. The accelerator made major contributions in four distinct areas of research: high-energy particle physics, nuclear heavy-ion physics, medical research and therapy, and space-related studies of radiation damage and heavy particles in space.

A Particle Model Explaining Mass and Relativity in a Physical Way

NASA Astrophysics Data System (ADS)

Giese, Albrecht

Physicists' understanding of relativity and the way it is handled is up to present days dominated by the interpretation of Albert Einstein, who related relativity to specific properties of space and time. The principal alternative to Einstein's interpretation is based on a concept proposed by Hendrik A. Lorentz, which uses knowledge of classical physics alone to explain relativistic phenomena. In this paper, we will show that on the one hand the Lorentz-based interpretation provides a simpler mathematical way of arriving at the known results for both Special and General Relativity. On the other hand, it is able to solve problems which have remained open to this day. Furthermore, a particle model will be presented, based on Lorentzian relativity and the quantum mechanical concept of Louis de Broglie, which explains the origin of mass without the use of the Higgs mechanism. It is based on the finiteness of the speed of light and provides classical results for particle properties which are currently only accessible through quantum mechanics.

Effects Of Crystallographic Properties On The Ice Nucleation Properties Of Volcanic Ash Particles

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

Kulkarni, Gourihar R.; Nandasiri, Manjula I.; Zelenyuk, Alla

2015-04-28

Specific chemical and physical properties of volcanic ash particles that could affect their ability to induce ice formation are poorly understood. In this study, the ice nucleating properties of size-selected volcanic ash and mineral dust particles in relation to their surface chemistry and crystalline structure at temperatures ranging from –30 to –38 °C were investigated in deposition mode. Ice nucleation efficiency of dust particles was higher compared to ash particles at all temperature and relative humidity conditions. Particle characterization analysis shows that surface elemental composition of ash and dust particles was similar; however, the structural properties of ash samples weremore » different.« less

A Model for Generation of Martian Surface Dust, Soil and Rock Coatings: Physical vs. Chemical Interactions, and Palagonitic Plus Hydrothermal Alteration

NASA Technical Reports Server (NTRS)

Bishop, J. L.; Murchie, S.; Pieters, C.; Zent, A.

1999-01-01

This model is one of many possible scenarios to explain the generation of the current surface material on Mars using chemical, magnetic and spectroscopic data from Mars and geologic analogs from terrestrial sites. One basic premise is that there are physical and chemical interactions of the atmospheric dust particles and that these two processes create distinctly different results. Physical processes distribute dust particles on rocks, forming physical rock coatings, and on the surface between rocks forming soil units; these are reversible processes. Chemical reactions of the dust/soil particles create alteration rinds on rock surfaces or duricrust surface units, both of which are relatively permanent materials. According to this model the mineral components of the dust/soil particles are derived from a combination of "typical" palagonitic weathering of volcanic ash and hydrothermally altered components, primarily from steam vents or fumeroles. Both of these altered materials are composed of tiny particles, about 1 micron or smaller, that are aggregates of silicates and iron oxide/oxyhydroxide/sulfate phases. Additional information is contained in the original extended abstract.

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

Optical, physical, and chemical properties of springtime aerosol over Barrow Alaska in 2008

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

Shantz, Nicole C.; Gultepe, Ismail; Andrews, Elisabeth

2014-03-06

Airborne observations from four flights during the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) are used to examine some cloud-free optical, physical, and chemical properties of aerosol particles in the springtime Arctic troposphere. The number concentrations of particles larger than 0.12 μm (Na>120), important for light extinction and cloud droplet formation, ranged from 15 to 2260 cm -3, with the higher Na>120 cases dominated by measurements from two flights of long-range transported biomass burning (BB) aerosols. The two other flights examined here document a relatively clean aerosol and an Arctic Haze aerosol impacted by larger particles largely composed of dust.more » For observations from the cleaner case and the BB cases, the particle light scattering coefficients at low relative humidity (RH<20%) increased nonlinearly with increasing Na>120, driven mostly by an increase in mean sizes of particles with increasing Na>120 (BB cases). For those three cases, particle light absorption coefficients also increased nonlinearly with increasing Na>120 and linearly with increasing submicron particle volume concentration. In addition to black carbon, brown carbon was estimated to have increased light absorption coefficients by 27% (450 nm wavelength) and 14% (550 nm) in the BB cases. For the case with strong dust influence, the absorption relative to submicron particle volume was small compared with the other cases. There was a slight gradient of Passive Cavity Aerosol Spectrometer Probe (PCASP) mean volume diameter (MVD) towards smaller sizes with increasing height, which suggests more scavenging of the more elevated particles, consistent with a typically longer lifetime of particles higher in the atmosphere. However, in approximately 10% of the cases, the MVD increased (>0.4 μm) with increasing altitude, suggesting transport of larger fine particle mass (possibly coarse particle mass) at high levels over the Arctic. This may be because of transport of larger particles at higher elevations and relatively slow deposition to the surface.« less

Aspects of string phenomenology in particle physics and cosmology

NASA Astrophysics Data System (ADS)

Antoniadis, I.

2017-12-01

I discuss possible connections between several scales in particle physics and cosmology, such the the electroweak, inflation, dark energy and Planck scales. In particular, I discuss the physics of extra dimensions and low scale gravity that are motivated from the problem of mass hierarchy, providing an alternative to low energy supersymmetry. I describe their realization in type I string theory with D-branes and I present the main experimental predictions in particle accelerators and their implications in cosmology. I also show that low-mass-scale string compactifications, with a generic D-brane configuration that realizes the Standard Model by open strings, can explain the relatively broad peak in the diphoton invariant mass spectrum at 750 GeV recently reported by the ATLAS and CMS collaborations.

Acceleration technologies for charged particles: an introduction

NASA Astrophysics Data System (ADS)

Carter, Richard G.

2011-01-01

Particle accelerators have many important uses in scientific experiments, in industry and in medicine. This paper reviews the variety of technologies which are used to accelerate charged particles to high energies. It aims to show how the capabilities and limitations of these technologies are related to underlying physical principles. The paper emphasises the way in which different technologies are used together to convey energy from the electrical supply to the accelerated particles.

A Physics Finale.

ERIC Educational Resources Information Center

Haynes, Gail E.

1991-01-01

A third-semester physics course that covers the topics of atomic physics, the theory of relativity, and nuclear energy is described. Activities that include the phenomenon of radioactivity, field trips to a nuclear power plant, a simulation of a chain reaction, and comparing the size of atomic particles are presented. (KR)

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

Investigations in γ-Ray Astrophysics and Astroparticle Physics

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

Krennrich, Frank

This report describes the status of data analysis efforts, results and publications of research grant DE-SC0009917. The research is focused on TeV gamma-ray studies of astrophysical sources and related particle physics questions.

Project Physics Tests 6, The Nucleus.

ERIC Educational Resources Information Center

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

Test items relating to Project Physics Unit 6 are presented in this booklet. Included are 70 multiple-choice and 24 problem-and-essay questions. Nuclear physics fundamentals are examined with respect to the shell model, isotopes, neutrons, protons, nuclides, charge-to-mass ratios, alpha particles, Becquerel's discovery, gamma rays, cyclotrons,…

Measurement-induced-nonlocality for Dirac particles in Garfinkle-Horowitz-Strominger dilation space-time

NASA Astrophysics Data System (ADS)

He, Juan; Xu, Shuai; Ye, Liu

2016-05-01

We investigate the quantum correlation via measurement-induced-nonlocality (MIN) for Dirac particles in Garfinkle-Horowitz-Strominger (GHS) dilation space-time. It is shown that the physical accessible quantum correlation decreases as the dilation parameter increases monotonically. Unlike the case of scalar fields, the physical accessible correlation is not zero when the Hawking temperature is infinite owing to the Pauli exclusion principle and the differences between Fermi-Dirac and Bose-Einstein statistics. Meanwhile, the boundary of MIN related to Bell-violation is derived, which indicates that MIN is more general than quantum nonlocality captured by the violation of Bell-inequality. As a by-product, a tenable quantitative relation about MIN redistribution is obtained whatever the dilation parameter is. In addition, it is worth emphasizing that the underlying reason why the physical accessible correlation and mutual information decrease is that they are redistributed to the physical inaccessible regions.

Physical and Mechanical Properties of LoVAR: A New Lightweight Particle-Reinforced Fe-36Ni Alloy

NASA Technical Reports Server (NTRS)

Stephenson, Timothy; Tricker, David; Tarrant, Andrew; Michel, Robert; Clune, Jason

2015-01-01

Fe-36Ni is an alloy of choice for low thermal expansion coefficient (CTE) for optical, instrument and electrical applications in particular where dimensional stability is critical. This paper outlines the development of a particle-reinforced Fe-36Ni alloy that offers reduced density and lower CTE compared to the matrix alloy. A summary of processing capability will be given relating the composition and microstructure to mechanical and physical properties.

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming

NASA Astrophysics Data System (ADS)

Brown, Eric; Jaeger, Heinrich M.

2014-04-01

Shear thickening is a type of non-Newtonian behavior in which the stress required to shear a fluid increases faster than linearly with shear rate. Many concentrated suspensions of particles exhibit an especially dramatic version, known as Discontinuous Shear Thickening (DST), in which the stress suddenly jumps with increasing shear rate and produces solid-like behavior. The best known example of such counter-intuitive response to applied stresses occurs in mixtures of cornstarch in water. Over the last several years, this shear-induced solid-like behavior together with a variety of other unusual fluid phenomena has generated considerable interest in the physics of densely packed suspensions. In this review, we discuss the common physical properties of systems exhibiting shear thickening, and different mechanisms and models proposed to describe it. We then suggest how these mechanisms may be related and generalized, and propose a general phase diagram for shear thickening systems. We also discuss how recent work has related the physics of shear thickening to that of granular materials and jammed systems. Since DST is described by models that require only simple generic interactions between particles, we outline the broader context of other concentrated many-particle systems such as foams and emulsions, and explain why DST is restricted to the parameter regime of hard-particle suspensions. Finally, we discuss some of the outstanding problems and emerging opportunities.

On the contributions of astroparticle physics to cosmology

NASA Astrophysics Data System (ADS)

Falkenburg, Brigitte

2014-05-01

Studying astroparticle physics sheds new light on scientific explanation and on the ways in which cosmology is empirically underdetermined or not. Astroparticle physics extends the empirical domain of cosmology from purely astronomical data to "multi-messenger astrophysics", i.e., measurements of all kinds of cosmic rays including very high energetic gamma rays, neutrinos, and charged particles. My paper investigates the ways in which these measurements contribute to cosmology and compares them with philosophical views about scientific explanation, the relation between theory and data, and scientific realism. The "standard models" of cosmology and particle physics lack of unified foundations. Both are "piecemeal physics" in Cartwright's sense, but contrary to her metaphysics of a "dappled world" the work in both fields of research aims at unification. Cosmology proceeds "top-down", from models to data and from large scale to small-scale structures of the universe. Astroparticle physics proceeds "bottom-up", from data taking to models and from subatomic particles to large-scale structures of the universe. In order to reconstruct the causal stories of cosmic rays and the nature of their sources, several pragmatic unifying strategies are employed. Standard views about scientific explanation and scientific realism do not cope with these "bottom-up" strategies and the way in which they contribute to cosmology. In addition it has to be noted that the shift to "multi-messenger astrophysics" transforms the relation between cosmological theory and astrophysical data in a mutually holistic way.

Complete particle-pair annihilation as a dynamical signature of the spectral singularity

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

Li, G.R.; Zhang, X.Z.; Song, Z., E-mail: nkquantum@gmail.com

2014-10-15

Motivated by the physical relevance of a spectral singularity of interacting many-particle system, we explore the dynamics of two bosons as well as fermions in one-dimensional system with imaginary delta interaction strength. Based on the exact solution, it shows that the two-particle collision leads to amplitude-reduction of the wave function. For fermion pair, the amplitude-reduction depends on the spin configuration of two particles. In both cases, the residual amplitude can vanish when the relative group velocity of two single-particle Gaussian wave packets with equal width reaches the magnitude of the interaction strength, exhibiting complete particle-pair annihilation at the spectral singularity.more » - Highlights: • We investigate the physical relevance of a spectral singularity. • The two-particle collision leads to amplitude-reduction of the wave function. • There is a singularity spectrum which leads to complete particle-pair annihilation. • Complete particle-pair annihilation can only occur for two distinguishable bosons and singlet fermions. • Pair annihilation provides a detection method of the spectral singularity in the experiment.« less

The Relative Effectiveness of the Use of Static and Dynamic Mechanical Models in Teaching Elementary School Children the Theoretical Concept--The Particle Nature of Matter.

ERIC Educational Resources Information Center

Ziegler, Robert Edward

This study is concerned with determining the relative effectiveness of a static and dynamic theoretical model in teaching elementary school students to use the particle idea of matter when explaining certain physical phenomena. A clinical method of personal individual interview-testing, teaching, and retesting of a random sample population from…

THE USE OF STATIC AND DYNAMIC MECHANICAL MODELS IN TEACHING ASPECTS OF THE THEORETICAL CONCEPT, THE PARTICLE NATURE OF MATTER.

ERIC Educational Resources Information Center

PELLA, MILTON O.; ZIEGLER, ROBERT E.

THE RELATIVE EFFECTIVENESS OF TWO TYPES OF MECHANICAL MODELS FOR TEACHING ELEMENTARY SCHOOL STUDENTS TO USE THE PARTICLE IDEA OF MATTER TO EXPLAIN CERTAIN PHYSICAL PHENOMENA WAS INVESTIGATED. SUBJECTS WERE RANDOMLY SELECTED FROM STUDENTS ENROLLED IN GRADES TWO THROUGH SIX IN A SCHOOL SYSTEM. A SERIES OF DEMONSTRATIONS AND RELATED QUESTIONS WERE…

Oxford dictionary of Physics

NASA Astrophysics Data System (ADS)

Isaacs, Alan

The dictionary is derived from the Concise Science Dictionary, first published by Oxford University Press in 1984 (third edition, 1996). It consists of all the entries relating to physics in that dictionary, together with some of those entries relating to astronomy that are required for an understanding of astrophysics and many entries that relate to physical chemistry. It also contains a selection of the words used in mathematics that are relevant to physics, as well as the key words in metal science, computing, and electronics. For this third edition a number of words from quantum field physics and statistical mechanics have been added. Cosmology and particle physics have been updated and a number of general entries have been expanded.

Revealing the jet substructure in a compressed spectrum of new physics

NASA Astrophysics Data System (ADS)

Han, Chengcheng; Park, Myeonghun

2016-07-01

The physics beyond the Standard Model with parameters of the compressed spectrum is well motivated both in the theory side and with phenomenological reasons, especially related to dark matter phenomenology. In this letter, we propose a method to tag soft final state particles from a decaying process of a new particle in this parameter space. By taking a supersymmetric gluino search as an example, we demonstrate how the Large Hadron Collider experimental collaborations can improve sensitivity in these nontrivial search regions.

Relativity Based on Physical Processes Rather Than Space-Time

NASA Astrophysics Data System (ADS)

Giese, Albrecht

2013-09-01

Physicists' understanding of relativity and the way it is handled is at present dominated by the interpretation of Albert Einstein, who related relativity to specific properties of space and time. The principal alternative to Einstein's interpretation is based on a concept proposed by Hendrik A. Lorentz, which uses knowledge of classical physics to explain relativistic phenomena. In this paper, we will show that on the one hand the Lorentz-based interpretation provides a simpler mathematical way of arriving at the known results for both Special and General Relativity. On the other hand, it is able to solve problems which have remained open to this day. Furthermore, a particle model will be presented, based on Lorentzian relativity, which explains the origin of mass without the use of the Higgs mechanism, based on the finiteness of the speed of light, and which provides the classical results for particle properties that are currently only accessible through quantum mechanics.

Relationship between macrobenthos and physical habitat characters in tidal flat in eastern Seto Inland Sea, Japan.

PubMed

Otani, Sosuke; Kozuki, Yasunori; Kurata, Kengo; Ueda, Kaori; Nakai, Shigefumi; Murakami, Hitoshi

2008-01-01

The investigations were carried out at 6 tidal flats located on the eastern part of the Seto Inland Sea, Japan. This study was focused on physical characteristics of sediments, namely as particle size of sediment and difference in elevation, and generalizes the relationship between sediments and macrobenthos. A total of 192 species were collected at 187 stations at 6 tidal flats. Physical characteristics of sediment were classified into 9 groups by cluster analysis in relation to sediment particle size and difference in elevation. Those groups had also significant difference in physical characteristics of sediments, and were characterized by some specific macrobenthos species. Distribution of macrobenthos can be explained by the classification of physical characteristics of sediment. These findings show the possibility to predict the variety of macrobenthos community using the physical characteristics of sediment.

Finite grid instability and spectral fidelity of the electrostatic Particle-In-Cell algorithm

DOE PAGES

Huang, C. -K.; Zeng, Y.; Wang, Y.; ...

2016-10-01

The origin of the Finite Grid Instability (FGI) is studied by resolving the dynamics in the 1D electrostatic Particle-In-Cell (PIC) model in the spectral domain at the single particle level and at the collective motion level. The spectral fidelity of the PIC model is contrasted with the underlying physical system or the gridless model. The systematic spectral phase and amplitude errors from the charge deposition and field interpolation are quantified for common particle shapes used in the PIC models. Lastly, it is shown through such analysis and in simulations that the lack of spectral fidelity relative to the physical systemmore » due to the existence of aliased spatial modes is the major cause of the FGI in the PIC model.« less

Finite grid instability and spectral fidelity of the electrostatic Particle-In-Cell algorithm

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

Huang, C. -K.; Zeng, Y.; Wang, Y.

The origin of the Finite Grid Instability (FGI) is studied by resolving the dynamics in the 1D electrostatic Particle-In-Cell (PIC) model in the spectral domain at the single particle level and at the collective motion level. The spectral fidelity of the PIC model is contrasted with the underlying physical system or the gridless model. The systematic spectral phase and amplitude errors from the charge deposition and field interpolation are quantified for common particle shapes used in the PIC models. Lastly, it is shown through such analysis and in simulations that the lack of spectral fidelity relative to the physical systemmore » due to the existence of aliased spatial modes is the major cause of the FGI in the PIC model.« less

Novel dark matter phenomenology at colliders

NASA Astrophysics Data System (ADS)

Wardlow, Kyle Patrick

While a suitable candidate particle for dark matter (DM) has yet to be discovered, it is possible one will be found by experiments currently investigating physics on the weak scale. If discovered on that energy scale, the dark matter will likely be producible in significant quantities at colliders like the LHC, allowing the properties of and underlying physical model characterizing the dark matter to be precisely determined. I assume that the dark matter will be produced as one of the decay products of a new massive resonance related to physics beyond the Standard Model, and using the energy distributions of the associated visible decay products, develop techniques for determining the symmetry protecting these potential dark matter candidates from decaying into lighter Standard Model (SM) particles and to simultaneously measure the masses of both the dark matter candidate and the particle from which it decays.

Large underground, liquid based detectors for astro-particle physics in Europe: scientific case and prospects

NASA Astrophysics Data System (ADS)

Autiero, D.; Äystö, J.; Badertscher, A.; Bezrukov, L.; Bouchez, J.; Bueno, A.; Busto, J.; Campagne, J.-E.; Cavata, Ch; Chaussard, L.; de Bellefon, A.; Déclais, Y.; Dumarchez, J.; Ebert, J.; Enqvist, T.; Ereditato, A.; von Feilitzsch, F.; Fileviez Perez, P.; Göger-Neff, M.; Gninenko, S.; Gruber, W.; Hagner, C.; Hess, M.; Hochmuth, K. A.; Kisiel, J.; Knecht, L.; Kreslo, I.; Kudryavtsev, V. A.; Kuusiniemi, P.; Lachenmaier, T.; Laffranchi, M.; Lefievre, B.; Lightfoot, P. K.; Lindner, M.; Maalampi, J.; Maltoni, M.; Marchionni, A.; Marrodán Undagoitia, T.; Marteau, J.; Meregaglia, A.; Messina, M.; Mezzetto, M.; Mirizzi, A.; Mosca, L.; Moser, U.; Müller, A.; Natterer, G.; Oberauer, L.; Otiougova, P.; Patzak, T.; Peltoniemi, J.; Potzel, W.; Pistillo, C.; Raffelt, G. G.; Rondio, E.; Roos, M.; Rossi, B.; Rubbia, A.; Savvinov, N.; Schwetz, T.; Sobczyk, J.; Spooner, N. J. C.; Stefan, D.; Tonazzo, A.; Trzaska, W.; Ulbricht, J.; Volpe, C.; Winter, J.; Wurm, M.; Zalewska, A.; Zimmermann, R.

2007-11-01

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

Inertial microfluidic physics.

PubMed

Amini, Hamed; Lee, Wonhee; Di Carlo, Dino

2014-08-07

Microfluidics has experienced massive growth in the past two decades, and especially with advances in rapid prototyping researchers have explored a multitude of channel structures, fluid and particle mixtures, and integration with electrical and optical systems towards solving problems in healthcare, biological and chemical analysis, materials synthesis, and other emerging areas that can benefit from the scale, automation, or the unique physics of these systems. Inertial microfluidics, which relies on the unconventional use of fluid inertia in microfluidic platforms, is one of the emerging fields that make use of unique physical phenomena that are accessible in microscale patterned channels. Channel shapes that focus, concentrate, order, separate, transfer, and mix particles and fluids have been demonstrated, however physical underpinnings guiding these channel designs have been limited and much of the development has been based on experimentally-derived intuition. Here we aim to provide a deeper understanding of mechanisms and underlying physics in these systems which can lead to more effective and reliable designs with less iteration. To place the inertial effects into context we also discuss related fluid-induced forces present in particulate flows including forces due to non-Newtonian fluids, particle asymmetry, and particle deformability. We then highlight the inverse situation and describe the effect of the suspended particles acting on the fluid in a channel flow. Finally, we discuss the importance of structured channels, i.e. channels with boundary conditions that vary in the streamwise direction, and their potential as a means to achieve unprecedented three-dimensional control over fluid and particles in microchannels. Ultimately, we hope that an improved fundamental and quantitative understanding of inertial fluid dynamic effects can lead to unprecedented capabilities to program fluid and particle flow towards automation of biomedicine, materials synthesis, and chemical process control.

ASSESSMENT OF THE LIQUID WATER CONTENT OF SUMMERTIME AEROSOL IN THE SOUTHEAST UNITED STATES

EPA Science Inventory

The concentration of aerosol liquid water mass represents an important parameter for understanding the physical properties of PM2.5 in the atmosphere. Increases in ambient relative humidity can increase aerosol liquid water and thus the composite particle mass and particle volu...

Light as a Fundamental Particle

ERIC Educational Resources Information Center

Weinberg, Steven

1975-01-01

Presents two arguments concerning the role of the photon. One states that the photon is just another particle distinguished by a particular value of charge, spin, mass, lifetime, and interaction properties. The second states that the photon plays a fundamental role with a deep relation to ultimate formulas of physics. (GS)

Physical and environmental factors affecting the persistence of explosives particles (Conference Presentation)

NASA Astrophysics Data System (ADS)

Papantonakis, Michael R.; Nguyen, Viet K.; Furstenberg, Robert; White, Caitlyn; Shuey, Melissa; Kendziora, Christopher A.; McGill, R. Andrew

2017-05-01

Knowledge of the persistence of trace explosives materials is critical to aid the security community in designing detection methods and equipment. The physical and environmental factors affecting the lifetimes of particles include temperature, airflow, interparticle distance, adlayers, humidity, particle field size and vapor pressure. We are working towards a complete particle persistence model that captures the relative importance of these effects to allow the user, with known environmental conditions, to predict particle lifetimes for explosives or other chemicals. In this work, particles of explosives are sieved onto smooth glass substrates using particle sizes and loadings relevant to those deposited by fingerprint deposition. The coupon is introduced into a custom flow cell and monitored under controlled airflow, humidity and temperature. Photomicroscopy images of the sample taken at fixed time intervals are analyzed to monitor particle sublimation and characterized as a size-independent radial sublimation velocity for each particle in the ensemble. In this paper we build on previous work by comparing the relationship between sublimation of different materials and their vapor pressures. We also describe the influence of a sebum adlayer on particle sublimation, allowing us to better model `real world' samples.

Progress in understanding fission-product behaviour in coated uranium-dioxide fuel particles

NASA Astrophysics Data System (ADS)

Barrachin, M.; Dubourg, R.; Kissane, M. P.; Ozrin, V.

2009-03-01

Supported by results of calculations performed with two analytical tools (MFPR, which takes account of physical and chemical mechanisms in calculating the chemical forms and physical locations of fission products in UO2, and MEPHISTA, a thermodynamic database), this paper presents an investigation of some important aspects of the fuel microstructure and chemical evolutions of irradiated TRISO particles. The following main conclusions can be identified with respect to irradiated TRISO fuel: first, the relatively low oxygen potential within the fuel particles with respect to PWR fuel leads to chemical speciation that is not typical of PWR fuels, e.g., the relatively volatile behaviour of barium; secondly, the safety-critical fission-product caesium is released from the urania kernel but the buffer and pyrolytic-carbon coatings could form an important chemical barrier to further migration (i.e., formation of carbides). Finally, significant releases of fission gases from the urania kernel are expected even in nominal conditions.

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.

Physics of spacecraft-based interplanetary dust collection by impact into low-density media

NASA Technical Reports Server (NTRS)

Anderson, William W.; Ahrens, T. J.

1994-01-01

A spacecraft encountering an interplanetary dust particle (IDP) at a relative velocity of several kilometers per second may be used to capture that particle for in situ analysis or for analysis upon Earth return. In this paper we study the impact of a dust particle into a low-density medium (i.e., a foam) such that the foam dissipates the kinetic energy of impact over a sufficient distance to stop the particle without destroying it.

Twenty years of space radiation physics at the BNL AGS and NASA Space Radiation Laboratory.

PubMed

Miller, J; Zeitlin, C

2016-06-01

Highly ionizing atomic nuclei HZE in the GCR will be a significant source of radiation exposure for humans on extended missions outside low Earth orbit. Accelerators such as the LBNL Bevalac and the BNL AGS, designed decades ago for fundamental nuclear and particle physics research, subsequently found use as sources of GCR-like particles for ground-based physics and biology research relevant to space flight. The NASA Space Radiation Laboratory at BNL was constructed specifically for space radiation research. Here we review some of the space-related physics results obtained over the first 20 years of NASA-sponsored research at Brookhaven. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

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

What Is Physical Oceanography? A Learning Experience for Coastal and Oceanic Awareness Studies, No. 217. [Project COAST].

ERIC Educational Resources Information Center

Delaware Univ., Newark. Coll. of Education.

This unit is concerned with an overview of physical oceanography - the study of currents, tides, waves, and particle movements. The activities are designed for use by junior high school age students. Included in the unit are activities related to properties of sea water, physical phenomena of the ocean, and physical features of the ocean.…

Recent Improvements of Particle and Heavy Ion Transport code System: PHITS

NASA Astrophysics Data System (ADS)

Sato, Tatsuhiko; Niita, Koji; Iwamoto, Yosuke; Hashimoto, Shintaro; Ogawa, Tatsuhiko; Furuta, Takuya; Abe, Shin-ichiro; Kai, Takeshi; Matsuda, Norihiro; Okumura, Keisuke; Kai, Tetsuya; Iwase, Hiroshi; Sihver, Lembit

2017-09-01

The Particle and Heavy Ion Transport code System, PHITS, has been developed under the collaboration of several research institutes in Japan and Europe. This system can simulate the transport of most particles with energy levels up to 1 TeV (per nucleon for ion) using different nuclear reaction models and data libraries. More than 2,500 registered researchers and technicians have used this system for various applications such as accelerator design, radiation shielding and protection, medical physics, and space- and geo-sciences. This paper summarizes the physics models and functions recently implemented in PHITS, between versions 2.52 and 2.88, especially those related to source generation useful for simulating brachytherapy and internal exposures of radioisotopes.

A model for accretion of the terrestrial planets

NASA Technical Reports Server (NTRS)

Weidenschilling, S. J.

1974-01-01

One possible origin of the terrestrial planets involves their formation by gravitational accretion of particles originally in Keplerian orbits about the sun. Some implications of this theory are considered. A formal expression for the rate of mass accretion by a planet is developed. The formal singularity of the gravitational collision cross section for low relative velocities is shown to be without physical significance when the accreting bodies are in heliocentric orbits. The distribution of particle velocities relative to an accreting planet is considered; the mean velocity increases with time. The internal temperature of an accreting planet is shown to depend simply on the accretion rate. A simple and physically reasonable approximate expression for a planetary accretion rate is proposed.

Balloon and Button Spectroscopy: A Hands-On Approach to Light and Matter

ERIC Educational Resources Information Center

Ribaudo, Joseph

2016-01-01

Without question, one of the most useful tools an astronomer or physicist can employ to study the universe is spectroscopy. However, for students in introductory physics or astronomy classes, spectroscopy is a relatively abstract concept that combines new physics topics such as thermal radiation, atomic physics, and the wave and particle nature of…

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.

Center for Theoretical Underground Physics and Related Areas - CETUP*2013 Summer Program

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

Szczerbinska, Barbara

In response to an increasing interest in experiments conducted at deep underground facilities around the world, in 2010 the theory community has proposed a new initiative - a Center for Theoretical Underground Physics and Related Areas (CETUP*). The main goal of CETUP* is to bring together people with different talents and skills to address the most exciting questions in particle and nuclear physics, astrophysics, geosciences, and geomicrobiology. Scientists invited to participate in the program do not only provide theoretical support to the underground science, they also examine underlying universal questions of the 21 st century including: What is dark matter?,more » What are the masses of neutrinos?, How have neutrinos shaped the evolution of the universe?, How were the elements from iron to uranium made?, What is the origin and thermal history of the Earth? The mission of the CETUP* is to promote an organized research in physics, astrophysics, geoscience, geomicrobiology and other fields related to the underground science via individual and collaborative research in dynamic atmosphere of intense scientific interactions. Our main goal is to bring together scientists scattered around the world, promote the deep underground science and provide a stimulating environment for creative thinking and open communication between researches of varying ages and nationalities. CETUP*2014 included 5 week long program (June 24 – July 26, 2013) covering various theoretical and experimental aspects of Dark Matter, Neutrino Physics and Astrophysics. Two week long session focused on Dark Matter (June 24-July 6) was followed by two week long program on Neutrino Physics and Astrophysics (July 15-26). The VII th International Conference on Interconnections between Particle Physics and Cosmology (PPC) was sandwiched between these sessions (July 8-13) covering the subjects of dark matter, neutrino physics, gravitational waves, collider physics and other from both theoretical end experimental aspects. PPC was initiated at Texas A&M University in 2007 and travelled to many places which include Geneva, Turin, Seoul (S. Korea) etc. during the last 5 years before coming back to USA. The objectives of CETUP* and PPC 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, develop a theoretical understanding of the three-neutrino oscillation parameters, provide a stimulating venue for exchange of scientific ideas among experts in neutrino physics and unification, connect with venues for public education outreach to communicate the importance of dark matter, neutrino research, and support of investment in science education, support mission of the Snowmass meeting and allow for extensive discussions of the ideas crucial for the future of high energy physics. The selected subjects represented the forefront of research topics in particle and nuclear physics, for example: recent precise measurements of all the neutrino mixing angles (that necessitate a theoretical roadmap for future experiments) or understanding of the nature of dark matter (that allows us to comprehend the composition of the cosmos better). All the covered topics are considered as a base for new physics beyond the Standard Model of particle physics.« less

Experiment and simulation of the fabrication process of lithium-ion battery cathodes for determining microstructure and mechanical properties

NASA Astrophysics Data System (ADS)

Forouzan, Mehdi M.; Chao, Chien-Wei; Bustamante, Danilo; Mazzeo, Brian A.; Wheeler, Dean R.

2016-04-01

The fabrication process of Li-ion battery electrodes plays a prominent role in the microstructure and corresponding cell performance. Here, a mesoscale particle dynamics simulation is developed to relate the manufacturing process of a cathode containing Toda NCM-523 active material to physical and structural properties of the dried film. Particle interactions are simulated with shifted-force Lennard-Jones and granular Hertzian functions. LAMMPS, a freely available particle simulator, is used to generate particle trajectories and resulting predicted properties. To make simulations of the full film thickness feasible, the carbon binder domain (CBD) is approximated with μm-scale particles, each representing about 1000 carbon black particles and associated binder. Metrics for model parameterization and validation are measured experimentally and include the following: slurry viscosity, elasticity of the dried film, shrinkage ratio during drying, volume fraction of phases, slurry and dried film densities, and microstructure cross sections. Simulation results are in substantial agreement with experiment, showing that the simulations reasonably reproduce the relevant physics of particle arrangement during fabrication.

Random walk, diffusion and mixing in simulations of scalar transport in fluid flows

NASA Astrophysics Data System (ADS)

Klimenko, A. Y.

2008-12-01

Physical similarity and mathematical equivalence of continuous diffusion and particle random walk form one of the cornerstones of modern physics and the theory of stochastic processes. In many applied models used in simulation of turbulent transport and turbulent combustion, mixing between particles is used to reflect the influence of the continuous diffusion terms in the transport equations. We show that the continuous scalar transport and diffusion can be accurately specified by means of mixing between randomly walking Lagrangian particles with scalar properties and assess errors associated with this scheme. This gives an alternative formulation for the stochastic process which is selected to represent the continuous diffusion. This paper focuses on statistical errors and deals with relatively simple cases, where one-particle distributions are sufficient for a complete description of the problem.

Techniques for Measuring Liquid Water Content Along a Trajectory

DTIC Science & Technology

1981-03-12

a problem in the small snow or ice crystal regions. When particle sizes ex- ceed the range of the instrument, the spectral distribution is... distribution will remain relatively constant beyond the physical size limitatiom Therefore. the trend of the distribution should be established from...diaMeri in- milimoeter. he marmum particle size (D) has previously been found- e..i."----U to be related to the s.ove of the distribution by an expression

University Physics, Study Guide, Revised Edition

NASA Astrophysics Data System (ADS)

Benson, Harris

1996-01-01

Partial table of contents: Vectors. One-Dimensional Kinematics. Particle Dynamics II. Work and Energy. Linear Momentum. Systems of Particles. Angular Momentum and Statics. Gravitation. Solids and Fluids. Oscillations. Mechanical Waves. Sound. First Law of Thermodynamics. Kinetic Theory. Entropy and the Second Law of Thermodynamics. Electrostatics. The Electric Field. Gauss's Law. Electric Potential. Current and Resistance. The Magnetic Field. Sources of the Magnetic Field. Electromagnetic Induction. Light: Reflection and Refraction. Lenses and Optical Instruments. Wave Optics I. Special Relativity. Early Quantum Theory. Nuclear Physics. Appendices. Answers to Odd-Numbered Exercises and Problems. Index.

Aerosolization properties, surface composition and physical state of spray-dried protein powders.

PubMed

Bosquillon, Cynthia; Rouxhet, Paul G; Ahimou, François; Simon, Denis; Culot, Christine; Préat, Véronique; Vanbever, Rita

2004-10-19

Powder aerosols made of albumin, dipalmitoylphosphatidylcholine (DPPC) and a protein stabilizer (lactose, trehalose or mannitol) were prepared by spray-drying and analyzed for aerodynamic behavior, surface composition and physical state. The powders exited a Spinhaler inhaler as particle aggregates, the size of which depending on composition, spray-drying parameters and airflow rate. However, due to low bulk powder tap density (<0.15 g/cm3), the aerodynamic size of a large fraction of aggregates remained respirable (<5 microm). Fine particle fractions ranged between 21% and 41% in an Andersen cascade impactor operated at 28.3 l/min, with mannitol and lactose providing the most cohesive and free-flowing powders, respectively. Particle surface analysis by X-ray photoelectron spectroscopy (XPS) revealed a surface enrichment with DPPC relative to albumin for powders prepared under certain spray-drying conditions. DPPC self-organized in a gel phase in the particle and no sugar or mannitol crystals were detected by X-ray diffraction. Water sorption isotherms showed that albumin protected lactose from moisture-induced crystallization. In conclusion, a proper combination of composition and spray-drying parameters allowed to obtain dry powders with elevated fine particle fractions (FPFs) and a physical environment favorable to protein stability.

Laser-driven deflection arrangements and methods involving charged particle beams

DOEpatents

Plettner, Tomas [San Ramon, CA; Byer, Robert L [Stanford, CA

2011-08-09

Systems, methods, devices and apparatus are implemented for producing controllable charged particle beams. In one implementation, an apparatus provides a deflection force to a charged particle beam. A source produces an electromagnetic wave. A structure, that is substantially transparent to the electromagnetic wave, includes a physical structure having a repeating pattern with a period L and a tilted angle .alpha., relative to a direction of travel of the charged particle beam, the pattern affects the force of the electromagnetic wave upon the charged particle beam. A direction device introduces the electromagnetic wave to the structure to provide a phase-synchronous deflection force to the charged particle beam.

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

Modeling Gas-Particle Partitioning of SOA: Effects of Aerosol Physical State and RH

NASA Astrophysics Data System (ADS)

Zuend, A.; Seinfeld, J.

2011-12-01

Aged tropospheric aerosol particles contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. In liquid aerosol particles non-ideal mixing of all species determines whether the condensed phase undergoes liquid-liquid phase separation or whether it is stable in a single mixed phase, and whether it contains solid salts in equilibrium with their saturated solution. The extended thermodynamic model AIOMFAC is able to predict such phase states by representing the variety of organic components using functional groups within a group-contribution concept. The number and composition of different condensed phases impacts the diversity of reaction media for multiphase chemistry and the gas-particle partitioning of semivolatile species. Recent studies show that under certain conditions biogenic and other organic-rich particles can be present in a highly viscous, semisolid or amorphous solid physical state, with consequences regarding reaction kinetics and mass transfer limitations. We present results of new gas-particle partitioning computations for aerosol chamber data using a model based on AIOMFAC activity coefficients and state-of-the-art vapor pressure estimation methods. Different environmental conditions in terms of temperature, relative humidity (RH), salt content, amount of precursor VOCs, and physical state of the particles are considered. We show how modifications of absorptive and adsorptive gas-particle mass transfer affects the total aerosol mass in the calculations and how the results of these modeling approaches compare to data of aerosol chamber experiments, such as alpha-pinene oxidation SOA. For a condensed phase in a mixed liquid state containing ammonium sulfate, the model predicts liquid-liquid phase separation up to high RH in case of, on average, moderately hydrophilic organic compounds, such as first generation oxidation products of alpha-pinene. The computations also reveal that treating liquid phases as ideal mixtures substantially overestimates the SOA mass, especially at high relative humidity.

On the physics of the pressure and temperature gradients in the edge of tokamak plasmas

NASA Astrophysics Data System (ADS)

Stacey, Weston M.

2018-04-01

An extended plasma fluid theory including atomic physics, radiation, electromagnetic and themodynamic forces, external sources of particles, momentum and energy, and kinetic ion orbit loss is employed to derive theoretical expressions that display the role of the various factors involved in the determination of the pressure and temperature gradients in the edge of tokamak plasmas. Calculations for current experiments are presented to illustrate the magnitudes of various effects including strong radiative and atomic physics edge cooling effects and strong reduction in ion particle and energy fluxes due to ion orbit loss in the plasma edge. An important new insight is the strong relation between rotation and the edge pressure gradient.

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

Relative distance between tracers as a measure of diffusivity within moving aggregates

NASA Astrophysics Data System (ADS)

Pönisch, Wolfram; Zaburdaev, Vasily

2018-02-01

Tracking of particles, be it a passive tracer or an actively moving bacterium in the growing bacterial colony, is a powerful technique to probe the physical properties of the environment of the particles. One of the most common measures of particle motion driven by fluctuations and random forces is its diffusivity, which is routinely obtained by measuring the mean squared displacement of the particles. However, often the tracer particles may be moving in a domain or an aggregate which itself experiences some regular or random motion and thus masks the diffusivity of tracers. Here we provide a method for assessing the diffusivity of tracer particles within mobile aggregates by measuring the so-called mean squared relative distance (MSRD) between two tracers. We provide analytical expressions for both the ensemble and time averaged MSRD allowing for direct identification of diffusivities from experimental data.

Pesticide spray application, behavior, and assessment: workshop proceedings

Treesearch

Richard B. Roberts

1976-01-01

Experts from relevant disciplines exchanged information on three important problems of pesticide spray technology. The four papers presented are Physical Parameters Relating to Pesticide Applications by N. B. Akesson and W. E. Yates; The Micrometeorology and Physics of Spray Particle Behavior by H. E. Cramer and D. G. Boyle;

Self-Paced Physics, Segments 32-36.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Five study segments of the Self-Paced Physics Course materials are presented in this seventh problems and solutions book used as a part of student course work. The content is related to magnetic fields, magnetic moments, forces on charged particles in magnetic fields, electron volts, cyclotron, electronic charge to mass ratio, current-carrying…

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).

Quantification of black carbon mixing state from traffic: Implications for aerosol optical properties

DOE PAGES

Willis, Megan D.; Healy, Robert M.; Riemer, Nicole; ...

2016-04-14

The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) inmore » two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Lastly, significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.« less

Physical and chemical characterization of actinides in soil from Johnston Atoll

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

Wolf, S.F.; Bates, J.K.; Buck, E.C.

1997-02-01

Characterization of the actinide content of a sample of contaminated coral soil from Johnston Atoll, the site of three non-nuclear destructs of nuclear warhead-carrying THOR missiles in 1962, revealed that >99% of the total actinide content is associated with discrete bomb fragments. After removal of these fragments, there was an inverse correlation between actinide content and soil particle size in particles from 43 to 0.4 {mu}m diameter. Detailed analyses of this remaining soil revealed no discrete actinide phase in these soil particles, despite measurable actinide content. Observations indicate that exposure to the environment has caused the conversion of relatively insolublemore » actinide oxides to the more soluble actinyl oxides and actinyl carbonate coordinated complexes. This process has led to dissolution of actinides from discrete particles and migration to the surrounding soil surfaces, resulting in a dispersion greater than would be expected by physical transport of discrete particles alone. 26 refs., 4 figs., 1 tab.« less

On total noncommutativity in quantum mechanics

NASA Astrophysics Data System (ADS)

Lahti, Pekka J.; Ylinen, Kari

1987-11-01

It is shown within the Hilbert space formulation of quantum mechanics that the total noncommutativity of any two physical quantities is necessary for their satisfying the uncertainty relation or for their being complementary. The importance of these results is illustrated with the canonically conjugate position and momentum of a free particle and of a particle closed in a box.

Composition in the Quantum World

NASA Astrophysics Data System (ADS)

Hall, Edward Jonathan

This thesis presents a problem for the foundations of quantum mechanics. It arises from the way that theory describes the composition of larger systems in terms of smaller ones, and renders untenable a wide range of interpretations of quantum mechanics. That quantum mechanics is difficult to interpret is old news, given the well-known Measurement Problem. But the problem I raise is quite different, and in important respects more fundamental. In brief: The physical world exhibits mereological structure: physical objects have parts, which in turn have parts, and so on. A natural way to try to represent this structure is by means of a particle theory, according to which the physical world consists entirely enduring physical objects which themselves have no proper parts, but aggregates of which are, or compose, all physical objects. Elementary, non-relativistic quantum mechanics can be cast in this mold--at least, according to the usual expositions of that theory. But herein lies the problem: the standard attempt to give a systematic particle interpretation to elementary quantum mechanics results in nonsense, thanks to the well-established principle of Permutation Invariance, which constrains the quantum -mechanical description of systems containing identical particles. Specifically, it follows from the most minimal principles of a particle interpretation (much weaker than those needed to generate the Measurement Problem), together with Permutation Invariance, that systems identical in composition must have the same physical state. In other words, systems which merely have the same numbers of the same types of particles are therefore, at all times, perfect physical duplicates. This conclusion is absurd: e.g., it is quite plausible that some of those particles which compose my body make up a system identical in composition to some pepperoni pizza. Yet no part of me is a qualitative physical duplicate of any pepperoni pizza. Perhaps "you are what you eat" --but not in this sense! In what follows I develop the principles needed to explore this problem, contrast it with the Measurement Problem, and consider, finally, how it should influence our judgments of the relative merits of the many extant interpretations of quantum mechanics.

Computer simulation of surface and film processes

NASA Technical Reports Server (NTRS)

Tiller, W. A.; Halicioglu, M. T.

1983-01-01

Adequate computer methods, based on interactions between discrete particles, provide information leading to an atomic level understanding of various physical processes. The success of these simulation methods, however, is related to the accuracy of the potential energy function representing the interactions among the particles. The development of a potential energy function for crystalline SiO2 forms that can be employed in lengthy computer modelling procedures was investigated. In many of the simulation methods which deal with discrete particles, semiempirical two body potentials were employed to analyze energy and structure related properties of the system. Many body interactions are required for a proper representation of the total energy for many systems. Many body interactions for simulations based on discrete particles are discussed.

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.

Physical Explanation of Archie's Porosity Exponent in Granular Materials: A Process-Based, Pore-Scale Numerical Study

NASA Astrophysics Data System (ADS)

Niu, Qifei; Zhang, Chi

2018-02-01

The empirical Archie's law has been widely used in geosciences and engineering to explain the measured electrical resistivity of many geological materials, but its physical basis has not been fully understood yet. In this study, we use a pore-scale numerical approach combining discrete element-finite difference methods to study Archie's porosity exponent m of granular materials over a wide porosity range. Numerical results reveal that at dilute states (e.g., porosity ϕ > 65%), m is exclusively related to the particle shape and orientation. As the porosity decreases, the electric flow in pore space concentrates progressively near particle contacts and m increases continuously in response to the intensified nonuniformity of the local electrical field. It is also found that the increase in m is universally correlated with the volume fraction of pore throats for all the samples regardless of their particle shapes, particle size range, and porosities.

Physically adjusted NDF (paNDF) system for lactating dairy cow rations. I: Deriving equations that identify factors that influence effectiveness of fiber

USDA-ARS?s Scientific Manuscript database

Physically effective neutral detergent fiber (peNDF) is defined as the fraction of NDF that stimulates chewing activity and contributes to the floating mat of large particles in the rumen. The objective of this work was to re-evaluate the concept of peNDF by quantitatively relating physical and chem...

Cascade Outreach Competitions for schools - an efficient way to introduce Particle Physics to many students

NASA Astrophysics Data System (ADS)

Watkins, Peter; Long, Lynne

2016-04-01

The Particle Physics group at the University of Birmingham has tried many different formats for Outreach competitions over recent years. We have found that a Cascade competition is a very efficient way to introduce Particle Physics concepts and experiments to a wide range of students. Small groups of students research, prepare and deliver a short presentation to other students. We will describe variations on the format of this type of competition and include some examples from our winning entries. All the material that we have used for these competitions is freely available on the web which we hope will make it easier for more groups to try similar competitions in the future. The name Cascade emphasises that the competition aims to introduce and inform many students about Particle Physics. However relatively limited time is required from researchers and teachers to enable this. The students research the material themselves and give their presentations, which often include novel demonstrations well matched to the target age group, to younger students or students of their own age. The participants also gain valuable experience in teamwork from the challenge of producing and delivering a clear and interesting talk by all members of the team, as well as improving their own understanding of the subject during the process.

Anisotropic particle in viscous shear flow: Navier slip, reciprocal symmetry, and Jeffery orbit.

PubMed

Zhang, Jiaolong; Xu, Xinpeng; Qian, Tiezheng

2015-03-01

The hydrodynamic reciprocal theorem for Stokes flows is generalized to incorporate the Navier slip boundary condition, which can be derived from Onsager's variational principle of least energy dissipation. The hydrodynamic reciprocal relations and the Jeffery orbit, both of which arise from the motion of a slippery anisotropic particle in a simple viscous shear flow, are investigated theoretically and numerically using the fluid particle dynamics method [Phys. Rev. Lett. 85, 1338 (2000)]. For a slippery elliptical particle in a linear shear flow, the hydrodynamic reciprocal relations between the rotational torque and the shear stress are studied and related to the Jeffery orbit, showing that the boundary slip can effectively enhance the anisotropy of the particle. Physically, by replacing the no-slip boundary condition with the Navier slip condition at the particle surface, the cross coupling between the rotational torque and the shear stress is enhanced, as manifested through a dimensionless parameter in both of the hydrodynamic reciprocal relations and the Jeffery orbit. In addition, simulations for a circular particle patterned with portions of no-slip and Navier slip are carried out, showing that the particle possesses an effective anisotropy and follows the Jeffery orbit as well. This effective anisotropy can be tuned by changing the ratio of no-slip portion to slip potion. The connection of the present work to nematic liquid crystals' constitutive relations is discussed.

Detection of cancerous cervical cells using physical adhesion of fluorescent silica particles and centripetal force

PubMed Central

Gaikwad, Ravi M.; Dokukin, Maxim E.; Iyer, K. Swaminathan; Woodworth, Craig D.; Volkov, Dmytro O.; Sokolov, Igor

2012-01-01

Here we describe a non-traditional method to identify cancerous human cervical epithelial cells in a culture dish based on physical interaction between silica beads and cells. It is a simple optical fluorescence-based technique which detects the relative difference in the amount of fluorescent silica beads physically adherent to surfaces of cancerous and normal cervical cells. The method utilizes the centripetal force gradient that occurs in a rotating culture dish. Due to the variation in the balance between adhesion and centripetal forces, cancerous and normal cells demonstrate clearly distinctive distributions of the fluorescent particles adherent to the cell surface over the culture dish. The method demonstrates higher adhesion of silica particles to normal cells compared to cancerous cells. The difference in adhesion was initially observed by atomic force microscopy (AFM). The AFM data were used to design the parameters of the rotational dish experiment. The optical method that we describe is much faster and technically simpler than AFM. This work provides proof of the concept that physical interactions can be used to accurately discriminate normal and cancer cells. PMID:21305062

Detection of a human intracisternal A-type retroviral particle antigenically related to HIV

NASA Technical Reports Server (NTRS)

Garry, R. F.; Fermin, C. D.; Hart, D. J.; Alexander, S. S.; Donehower, L. A.; Luo-Zhang, H.

1990-01-01

Sjogren's syndrome is an autoimmune disease that is characterized by dryness of the mouth and eyes. The loss of salivary and lacrimal gland function is accompanied by lymphocytic infiltration. Because similar symptoms and glandular pathology are observed in certain persons infected with human immunodeficiency virus (HIV), a search was initiated for a possible retroviral etiology in this syndrome. A human intracisternal A-type retroviral particle that is antigenically related to HIV was detected in lymphoblastoid cells exposed to homogenates of salivary tissue from patients with Sjogren's syndrome. Comparison of this retroviral particle to HIV indicates that they are distinguishable by several ultrastructural, physical, and enzymatic criteria.

Inquiring Minds

Science.gov Websites

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Physical and Chemical Characterization of Particles in the Upper Troposphere and Lower Stratosphere: Microanalysis of Aerosol Impactor Samples

NASA Technical Reports Server (NTRS)

Sheridan, Patrick J.

1999-01-01

Herein is reported activities to support the characterization of the aerosol in the upper troposphere (UT) and lower stratosphere (LS) collected during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA) missions in 1994. Through a companion proposal, another group was to measure the size distribution of aerosols in the 0.008 to 2 micrometer diameter range and to collect for us impactor samples of particles larger than about 0.02 gm. In the first year, we conducted laboratory studies related to particulate deposition patterns on our collection substrates, and have performed the analysis of many ASHOE/MAESA aerosol samples from 1994 using analytical electron microscopy (AEM). We have been building an "aerosol climatology" with these data that documents the types and relative abundances of particles observed at different latitudes and altitudes. The second year (and non-funded extension periods) saw continued analyses of impactor aerosol samples, including more ASHOE/MAESA samples, some northern hemisphere samples from the NASA Stratospheric Photochemistry Aerosols and Dynamics Expedition (SPADE) program for comparison, and a few aerosol samples from the NASA Stratospheric TRacers of Atmospheric Transport (STRAT) program. A high-resolution field emission microscope was used for the analysis and re-analysis of a number of samples to determine if this instrument was superior in performance to our conventional electron microscope. In addition, some basic laboratory studies were conducted to determine the minimum detectable and analyzable particle size for different types of aerosols. In all, 61 aerosol samples were analyzed, with a total of over 30,000 individual particle analyses. In all analyzed samples, sulfate particles comprised the major aerosol number fraction. It must be stressed that particles composed of more than one species, for example sulfate and organic carbon, were classified according to the major fraction. Thus, many of the particles classified as sulfate may have contained significant mass fractions of carbonaceous or other material. These particles for the most part did not show two physical phases, however. Nonsulfate particles were classified according to the physical and chemical characteristics of each particle, and were grouped into the major nonsulfate particle classes, including C-rich, crustal, metallic, and salts. Our UT and LS sample analyses indicate a maximum for crustal and C-rich particle abundance in the Northern Hemisphere upper troposphere, and a salt particle maximum in the Southern Hemisphere upper troposphere. Metallic particles are clearly more prevalent in the troposphere than in the stratosphere, but interhemispheric differences appear small.

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.

Electrodynamic balance-mass spectrometry of single particles as a new platform for atmospheric chemistry research

NASA Astrophysics Data System (ADS)

Birdsall, Adam W.; Krieger, Ulrich K.; Keutsch, Frank N.

2018-01-01

New analytical techniques are needed to improve our understanding of the intertwined physical and chemical processes that affect the composition of aerosol particles in the Earth's atmosphere, such as gas-particle partitioning and homogenous or heterogeneous chemistry, and their ultimate relation to air quality and climate. We describe a new laboratory setup that couples an electrodynamic balance (EDB) to a mass spectrometer (MS). The EDB stores a single laboratory-generated particle in an electric field under atmospheric conditions for an arbitrarily long length of time. The particle is then transferred via gas flow to an ionization region that vaporizes and ionizes the analyte molecules before MS measurement. We demonstrate the feasibility of the technique by tracking evaporation of polyethylene glycol molecules and finding agreement with a kinetic model. Fitting data to the kinetic model also allows determination of vapor pressures to within a factor of 2. This EDB-MS system can be used to study fundamental chemical and physical processes involving particles that are difficult to isolate and study with other techniques. The results of such measurements can be used to improve our understanding of atmospheric particles.

Relational particle models: I. Reconciliation with standard classical and quantum theory

NASA Astrophysics Data System (ADS)

Anderson, Edward

2006-04-01

This paper concerns the absolute versus relative motion debate. The Barbour and Bertotti (1982) work may be viewed as an indirectly set up relational formulation of a portion of Newtonian mechanics. I consider further direct formulations of this and argue that the portion in question—universes with zero total angular momentum that are conservative and with kinetic terms that are (homogeneous) quadratic in their velocities—is capable of accommodating a wide range of classical physics phenomena. Furthermore, as I develop in paper II, this relational particle model is a useful toy model for canonical general relativity. I consider what happens if one quantizes relational rather than absolute mechanics, indeed whether the latter is misleading. By exploiting Jacobi coordinates, I show how to access many examples of quantized relational particle models and then interpret these from a relational perspective. By these means, previous suggestions of bad semiclassicality for such models can be eluded. I show how small (particle number) universe relational particle model examples display eigenspectrum truncation, gaps, energy interlocking and counterbalanced total angular momentum. These features mean that these small universe models make interesting toy models for some aspects of closed-universe quantum cosmology. Meanwhile, these features do not compromise the recovery of reality as regards the practicalities of experimentation in a large universe such as our own.

Temporal fluctuations in grain size, organic materials and iron concentrations in intertidal surface sediment of San Francisco Bay

USGS Publications Warehouse

Thomson-Becker, E. A.; Luoma, S.N.

1985-01-01

The physical and chemical characteristics of the oxidized surface sediment in an estuary fluctuate temporally in response to physical forces and apparently-fluctuating inputs. These characteristics, which include grain size and concentrations of organic materials and iron, will influence both trace-metal geochemistry and bioavailability. Temporal trends in the abundance of fine particles, total organic carbon content (TOC), absorbance of extractable organic material (EOM), and concentration of extractable iron in the sediment of San Francisco Bay were assessed using data sets containing approximately monthly samples for periods of two to seven years. Changes in wind velocity and runoff result in monthly changes in the abundance of fine particles in the intertidal zone. Fine-grained particles are most abundant in the late fall/early winter when runoff is elevated and wind velocities are low; particles are coarser in the summer when runoff is low and wind velocities are consistently high. Throughout the bay, TOC is linearly related to fine particle abundance (r = 0.61). Temporal variability occurs in this relationship, as particles are poor in TOC relative to percent of fine particles in the early rainy season. Iron-poor particles also appear to enter the estuary during high runoff periods; while iron is enriched on particle surfaces in the summer. Concentrations of extractable iron and absorbance of EOM vary strongly from year to year. Highest absorbances of EOM occurred in the first year following the drought in 1976-77, and in 1982 and 1983 when river discharge was unusually high. Extractable-iron concentrations were also highest in 1976-77, but were very low in 1982 and 1983. ?? 1985 Dr W. Junk Publishers.

The 5th Generation model of Particle Physics

NASA Astrophysics Data System (ADS)

Lach, Theodore

2009-05-01

The Standard model of Particle Physics is able to account for all known HEP phenomenon, yet it is not able to predict the masses of the quarks or leptons nor can it explain why they have their respective values. The Checker Board Model (CBM) predicts that there are 5 generation of quarks and leptons and shows a pattern to those masses, namely each three quarks or leptons (within adjacent generations or within a generation) are related to each other by a geometric mean relationship. A 2D structure of the nucleus can be imaged as 2D plate spinning on its axis, it would for all practical circumstances appear to be a 3D object. The masses of the hypothesized ``up'' and ``dn'' quarks determined by the CBM are 237.31 MeV and 42.392 MeV respectively. These new quarks in addition to a lepton of 7.4 MeV make up one of the missing generations. The details of this new particle physics model can be found at the web site: checkerboard.dnsalias.net. The only areas were this theory conflicts with existing dogma is in the value of the mass of the Top quark. The particle found at Fermi Lab must be some sort of composite particle containing Top quarks.

Self-Paced Physics, Segments 19-23.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Five study segments of the Self-Paced Physics Course materials are presented in this fourth problems and solutions book used as a part of student course work. The subject matter is related to electric charges, insulators, Coulomb's law, electric fields, lines of force, solid angles, conductors, motion of charged particles, dipoles, electric flux,…

Physical meaning of two-particle HBT measurements in case of correlated emission

NASA Astrophysics Data System (ADS)

Bialas, A.; Zalewski, K.

2004-07-01

It is shown that, in the presence of correlations in particle emission, the measured HBT radii are related to the correlation range rather than to the size of the interaction volume. Only in the case of weak correlations the standard interpretation may be applicable. The earlier discussion [Phys. Rev. Lett. 68 (1992) 1109; Phys. Rev. C 49 (1994) 2722] of the short-range correlations in configuration space is generalized to include also the correlations of particle momenta.

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

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Fermilab | Science at Fermilab | Experiments & Projects

Science.gov Websites

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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

Outstanding questions: physics beyond the Standard Model.

PubMed

Ellis, John

2012-02-28

The Standard Model of particle physics agrees very well with experiment, but many important questions remain unanswered, among them are the following. What is the origin of particle masses and are they due to a Higgs boson? How does one understand the number of species of matter particles and how do they mix? What is the origin of the difference between matter and antimatter, and is it related to the origin of the matter in the Universe? What is the nature of the astrophysical dark matter? How does one unify the fundamental interactions? How does one quantize gravity? In this article, I introduce these questions and discuss how they may be addressed by experiments at the Large Hadron Collider, with particular attention to the search for the Higgs boson and supersymmetry.

Lecturer on tour!

NASA Astrophysics Data System (ADS)

1998-11-01

Readers may recall the interview with Professor Peter Kalmus which appeared in the July issue of Physics Education and which indicated his latest role of lecturer for the 1998-9 Institute of Physics Schools and Colleges Lecture series. This year's lecture is entitled `Particles and the universe' and the tour was due to begin in St Andrews, Scotland, late in September. Professor Kalmus will be looking at various aspects of particle physics, quantum physics and relativity, and discussing how they reveal the secrets of the beginning of our universe. His own experience of working at CERN, the European centre for particle physics in Switzerland, as well as at other international research facilities will provide a unique insight into activity in one of the most exciting areas of physics. The talks are aimed at the 16-19 age group but members of the public are also welcome to attend. They will act as an opportunity to gain a sneak preview of the dynamic new topics that will soon feature in the A-level syllabus arising from the Institute's 16-19 project. Further details of attendance are available from the local organizers, a list of whom may be obtained from Catherine Wilson in the Education Department at the Institute of Physics, 76 Portland Place, London W1N 3DH (tel: 0171 470 4800, fax: 0171 470 4848). The published schedule (as of September) for the lecture series consists of the following: Dates

Fluid casting of particle-based articles

DOEpatents

Menchhofer, Paul

1995-01-01

A method for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets or hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product.

An inadvertent capture cell for orbital debris and micrometeorites - The main electronics box thermal blanket of the solar maximum satellite

NASA Technical Reports Server (NTRS)

Rietmeijer, F. J. M.; Schramm, L. S.; Barrett, R. A.; Mckay, D. S.; Zook, H. A.

1986-01-01

The physical properties of impact features in the Solar Max main electronics box thermal blanket are consistent with hypervelocity impacts of particles in the near-earth space environment. The majority of particles are orbital debris and include spacecraft paints and bismuth-rich particles. At least 30 percent of all impact features are caused by micrometeorites, which include silicates and sulfides. Some micrometeorites survive impact with only minor shock-metamorphic effects or chemical fractionation. Currently calibration experiments are under way to relate flux to particle diameter (or mass).

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

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

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

2009-08-07

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

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.

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).

Discrete Element Method Modeling of Bedload Transport: Towards a physics-based link between bed surface variability and particle entrainment statistics

NASA Astrophysics Data System (ADS)

Ghasemi, A.; Borhani, S.; Viparelli, E.; Hill, K. M.

2017-12-01

The Exner equation provides a formal mathematical link between sediment transport and bed morphology. It is typically represented in a discrete formulation where there is a sharp geometric interface between the bedload layer and the bed, below which no particles are entrained. For high temporally and spatially resolved models, this is strictly correct, but typically this is applied in such a way that spatial and temporal fluctuations in the bed surface (bedforms and otherwise) are not captured. This limits the extent to which the exchange between particles in transport and the sediment bed are properly represented, particularly problematic for mixed grain size distributions that exhibit segregation. Nearly two decades ago, Parker (2000) provided a framework for a solution to this dilemma in the form of a probabilistic Exner equation, partially experimentally validated by Wong et al. (2007). We present a computational study designed to develop a physics-based framework for understanding the interplay between physical parameters of the bed and flow and parameters in the Parker (2000) probabilistic formulation. To do so we use Discrete Element Method simulations to relate local time-varying parameters to long-term macroscopic parameters. These include relating local grain size distribution and particle entrainment and deposition rates to long- average bed shear stress and the standard deviation of bed height variations. While relatively simple, these simulations reproduce long-accepted empirically determined transport behaviors such as the Meyer-Peter and Muller (1948) relationship. We also find that these simulations reproduce statistical relationships proposed by Wong et al. (2007) such as a Gaussian distribution of bed heights whose standard deviation increases with increasing bed shear stress. We demonstrate how the ensuing probabilistic formulations provide insight into the transport and deposition of both narrow and wide grain size distribution.

Homologies in Physics and Astrophysics

NASA Astrophysics Data System (ADS)

Bartlett, David F.; Cumalat, J. P.

2012-01-01

The genes of humans and chimpanzees are homologs. These genes are - in large measure - identical. From this detailed observation, we naturally suppose that both species evolved from a common ancestor. In particle physics the ordinary observed particles and their superymmetric partners are thought to be homologs, generated by a common "ancestor” , the Higgs particle. Experiments at CERN currently are testing this comfortable analogy of physics with biology. Neither the Higgs boson nor any supersymmetric particle has yet been found. We speculate that a variety of objects are homologs - evidence of an as yet undeveloped quantum theory of gravity to replace Dark Matter. A purely astronomical homology is the Vc - σ o relation which places nearly spherical elliptical galaxies just above well-formed spirals (SA & SB). Here the asymptotically- flat, circular velocity Vc is observed to be between 1 and 2 times the central bulge velocity dispersion σo over the range 60 km/s< σo <400 km/s (Ferrarese 2002, Fig 3). The Vc - σ o relation is difficult to explain with self-consistent equilibrium galaxy models (Courteau et al 2007). Here we give an explanation based on the Sinusoidal Potential, a non-Newtonian potential in which φ =-GM Cos[ko r]/r and ko=2 π /400 pc. We relate the lower limit of 60 km/s to the thermal velocity of protons at the” Broadhurst/Hirano & Hartnett” lookback redshift Z=105.6. This is the redshift where what was 400 pc then expands to 128 h-1 Mpc today. Further, at this Z the temperature of the universe was close to the Hartree Energy of 2 times 13.6 eV, an energy where protons have an rms speed of about 60 km/s.

The Correlation Between Small Dense LDL and Reactive Oxygen Metabolites in a Physical Activity Intervention in Hyperlipidemic Subjects.

PubMed

Kotani, Kazuhiko; Tsuzaki, Kokoro; Sakane, Naoki; Taniguchi, Nobuyuki

2012-06-01

Small dense low-density lipoprotein (sdLDL), which has a small LDL particle size with a greater susceptibility to oxidation, is considered a risk marker for cardiovascular disease (CVD). The diacron reactive oxygen metabolites (d-ROMs) have recently been introduced as a clinically useful oxidative stress-related marker. Physical activity can reduce the CVD risk. The present study investigated the correlation between the changes of the mean LDL particle size and the oxidative stress status, as assessed by the d-ROMs, in a physical activity intervention in hyperlipidemic subjects. We performed a 6-month intervention study of 30 hyperlipidemic subjects (12 male/18 female, mean age 64 years), focusing on a moderate physical activity increase. The clinical data, including the atherosclerotic risk factors besides the mean LDL particle size measured with the gel electrophoresis and the d-ROMs, were evaluated pre- and post-intervention. The mean LDL particle size was significantly larger in the post-intervention than in the pre-intervention evaluation (26.9 ± 0.3 (SD) vs. 27.1 ± 0.4 nm, P < 0.01), while the d-ROMs levels were significantly reduced in the post-intervention period compared to those at pre-intervention (319 ± 77 vs. 290 ± 73 U. Carr., P < 0.05). A stepwise multiple regression analysis revealed that there was an independent, significant and inverse correlation between the pre- and post-intervention changes of the d-ROMs and the mean LDL particle size (β = -0.55, P < 0.01). The intervention study suggests that sdLDL and oxidative stress can concomitantly affect the risk of developing CVD and that both factors can improve by even a moderate increase in physical activity among hyperlipidemic subjects.

Influence of formulation excipients and physical characteristics of inhalation dry powders on their aerosolization performance.

PubMed

Bosquillon, C; Lombry, C; Préat, V; Vanbever, R

2001-02-23

The objective of this study was to determine the effects of formulation excipients and physical characteristics of inhalation particles on their in vitro aerosolization performance, and thereby to maximize their respirable fraction. Dry powders were produced by spray-drying using excipients that are FDA-approved for inhalation as lactose, materials that are endogenous to the lungs as albumin and dipalmitoylphosphatidylcholine (DPPC); and/or protein stabilizers as trehalose or mannitol. Dry powders suitable for deep lung deposition, i.e. with an aerodynamic diameter of individual particles <3 microm, were prepared. They presented 0.04--0.25 g/cm(3) bulk tap densities, 3--5 microm geometric particle sizes, up to 90% emitted doses and 50% respirable fractions in the Andersen cascade impactor using a Spinhaler inhaler device. The incorporation of lactose, albumin and DPPC in the formulation all improved the aerosolization properties, in contrast to trehalose and the mannitol which decreased powder flowability. The relative proportion of the excipients affected aerosol performance as well. The lower the bulk powder tap density, the higher the respirable fraction. Optimization of in vitro aerosolization properties of inhalation dry powders can be achieved by appropriately selecting composition and physical characteristics of the particles.

Fermilab | Science at Fermilab | Experiments & Projects | Intensity

Science.gov Websites

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

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.

Aggregation in particle rich environments: a textural study of examples from volcanic eruptions, meteorite impacts, and fluidized bed processing

NASA Astrophysics Data System (ADS)

Mueller, Sebastian B.; Kueppers, Ulrich; Huber, Matthew S.; Hess, Kai-Uwe; Poesges, Gisela; Ruthensteiner, Bernhard; Dingwell, Donald B.

2018-04-01

Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 μm). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

Aggregation in particle rich environments: a textural study of examples from volcanic eruptions, meteorite impacts, and fluidized bed processing.

PubMed

Mueller, Sebastian B; Kueppers, Ulrich; Huber, Matthew S; Hess, Kai-Uwe; Poesges, Gisela; Ruthensteiner, Bernhard; Dingwell, Donald B

2018-01-01

Aggregation is a common process occurring in many diverse particulate gas mixtures (e.g. those derived from explosive volcanic eruptions, meteorite impact events, and fluid bed processing). It results from the collision and sticking of particles suspended in turbulent gas/air. To date, there is no generalized model of the underlying physical processes. Here, we investigate aggregates from 18 natural deposits (16 volcanic deposits and two meteorite impact deposits) as well as aggregates produced experimentally via fluidized bed techniques. All aggregates were analyzed for their size, internal structuring, and constituent particle size distribution. Commonalities and differences between the aggregate types are then used to infer salient features of the aggregation process. Average core to rim ratios of internally structured aggregates (accretionary lapilli) is found to be similar for artificial and volcanic aggregates but up to an order of magnitude different than impact-related aggregates. Rim structures of artificial and volcanic aggregates appear to be physically similar (single, sub-spherical, regularly-shaped rims) whereas impact-related aggregates more often show multiple or irregularly shaped rims. The particle size distributions (PSDs) of all three aggregate types are similar (< 200 μm). This proves that in all three environments, aggregation occurs under broadly similar conditions despite the significant differences in source conditions (particle volume fraction, particle size distribution, particle composition, temperature), residence times, plume conditions (e.g., humidity and temperature), and dynamics of fallout and deposition. Impact-generated and volcanic aggregates share many similarities, and in some cases may be indistinguishable without their stratigraphic context.

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.

Large & Small: Exploring the Laws of Nature

ERIC Educational Resources Information Center

Creutz, E.

1976-01-01

Illustrates how both large entities (such as stars and galaxies) and small entities (such as fundamental particles) obey the same physical laws. Discusses quantum mechanics, Newton's laws, and general relativity. (MLH)

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…

Medium and high-energy neutrino physics from a lunar base

NASA Technical Reports Server (NTRS)

Wilson, Thomas L.

1990-01-01

Neutrino astronomy at high energy levels conducted from the moon is treated by considering 'particle astronomy' as a part of physics and the moon as a neutrino detector. The ability to observe the Galactic center is described by means of a 1-1000 TeV 'window' related to the drop in flux of atmospheric neutrinos from the earth. The long-baseline particle physics which are described in terms of a lunar observatory are found to be possible exclusively from a lunar station. The earth's neutrinos can be eliminated for the observations of astrophysical sources, and other potential areas of investigation include neutrino oscillation and the moon's interior. Neutrino exploration of the earth-moon and antineutrino radionuclide imaging are also considered. The moon is concluded to be a significantly more effective orbital platform for the study of neutrino physics than orbiting satellites developed on earth.

A Visual Aid for Teaching Basic Concepts of Soil-Water Physics.

ERIC Educational Resources Information Center

Eshel, Amram

1997-01-01

Presents a visual aid designed to generate an image of water movement among soil particles using an overhead projector to teach the physical phenomena related to water status and water movement in the soil. Utilizes a base plate of thin transparent plastic, opaque plastic sheets, a plate of glass, and a colored aqueous solution. (AIM)

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Effect of Rolling Massage on Particle Moving Behaviour in Blood Vessels

NASA Astrophysics Data System (ADS)

Yi, Hou-Hui; Fan, Li-Juan; Yang, Xiao-Feng; Chen, Yan-Yan

2008-09-01

The rolling massage manipulation is a classic Chinese massage, which is expected to eliminate many diseases. Here the effect of the rolling massage on the particle moving property in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that the particle moving behaviour depends on the rolling velocity, the distance between particle position and rolling position. The average values, including particle translational velocity and angular velocity, increase as the rolling velocity increases almost linearly. The result is helpful to understand the mechanism of the massage and develop the rolling techniques.

Effects of Machine Traffic on the Physical Properties of Ash-Cap Soils

Treesearch

Leonard R. Johnson; Debbie Page-Dumroese; Han-Sup Han

2007-01-01

With pressure and vibration on a soil, air spaces between soil particles can be reduced by displaced soil particles. Activity associated with heavy machine traffic increases the density of the soil and can also increase the resistance of the soil to penetration. This paper reviews research related to disturbance of forest soils with a primary focus on compaction in ash...

Hidden sector behind the CKM matrix

NASA Astrophysics Data System (ADS)

Okawa, Shohei; Omura, Yuji

2017-08-01

The small quark mixing, described by the Cabibbo-Kobayashi-Maskawa (CKM) matrix in the standard model, may be a clue to reveal new physics around the TeV scale. We consider a simple scenario that extra particles in a hidden sector radiatively mediate the flavor violation to the quark sector around the TeV scale and effectively realize the observed CKM matrix. The lightest particle in the hidden sector, whose contribution to the CKM matrix is expected to be dominant, is a good dark matter (DM) candidate. There are many possible setups to describe this scenario, so that we investigate some universal predictions of this kind of model, focusing on the contribution of DM to the quark mixing and flavor physics. In this scenario, there is an explicit relation between the CKM matrix and flavor violating couplings, such as four-quark couplings, because both are radiatively induced by the particles in the hidden sector. Then, we can explicitly find the DM mass region and the size of Yukawa couplings between the DM and quarks, based on the study of flavor physics and DM physics. In conclusion, we show that DM mass in our scenario is around the TeV scale, and the Yukawa couplings are between O (0.01 ) and O (1 ). The spin-independent DM scattering cross section is estimated as O (10-9) [pb]. An extra colored particle is also predicted at the O (10 ) TeV scale.

Aqueous foams: a field of investigation at the frontier between chemistry and physics.

PubMed

Langevin, Dominique

2008-03-14

This paper reviews the properties of aqueous foams. The current state of knowledge is summarized briefly and the interdisciplinary aspects of this field of investigation are emphasized. Many phenomena are controlled by physical laws, but they are highly dependent upon the chemicals used as foam stabilizers: surfactants, polymers, particles. Most of the existing work is related to surfactants and polymer foams, and little is known yet for particle foams although research in this field is becoming popular. This article presents the general concepts used to describe the monolayers and the films and also some of the recent advances being made in this area.

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 micrometer diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 micrometer diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands form the thermal black body radiation. Recorded flame images were digitized and employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishing as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

Challenges in 21st Century Physics

NASA Technical Reports Server (NTRS)

Wilson, Thomas L.

2007-01-01

We are truly fortunate to live in one of the great epochs of human discovery, a time when science is providing new visions and understanding about ourselves and the world in which we live. At last, we are beginning to explore the Universe itself. One particularly exciting area of advancement is high-energy physics where several existing concepts will be put to the test. A brief survey will be given of accomplishments in 20th Century physics. These include relativity and quantum physics which have produced breakthroughs in cosmology, astrophysics, and high-energy particle physics. The current situation is then assessed, combining the last 100 years of progress with new 21st Century challenges about unification and where to go next. Finally, the future is upon us. The next frontier in experimental high-energy physics, the Large Hadron Collider (LHC) at CERN in Geneva, is scheduled to begin coming online this year (2007). The potential for the LHC to address several of the significant problems in physics today will be discussed, as this great accelerator examines the predictions of the Standard Model of particle physics and even cosmology. New physics and new science will surely emerge and a better vision of the world will unfold.

Optical and physical requirements for fluid particles marking trailing vortices from aircraft

NASA Technical Reports Server (NTRS)

Back, L. H.

1976-01-01

A theoretical study of the optical and physical requirements of marking trailing vortices that emanate from aircraft wings was carried out by considering particulate light-scattering properties, ability of particles to follow trailing vortices, and survival time of particles to vortex dissipation. Liquid droplets undergoing evaporation and molecular dispersion were investigated. Droplets should have lifetimes of about 300 sec. Droplet size should be about 1 micron to maximize light scattering with the minimum mass of liquid required. Droplets of this small size would spiral outward very slowly and essentially remain in the vortex cores. Nontoxic hygroscopic liquids, having an affinity for moisture in the air, have been identified. These liquids have relatively low vapor pressures of order 10 to the -5 mm Hg that would insure droplet persistence long enough to mark trailing vortices.

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.

GPU acceleration of particle-in-cell methods

NASA Astrophysics Data System (ADS)

Cowan, Benjamin; Cary, John; Meiser, Dominic

2015-11-01

Graphics processing units (GPUs) have become key components in many supercomputing systems, as they can provide more computations relative to their cost and power consumption than conventional processors. However, to take full advantage of this capability, they require a strict programming model which involves single-instruction multiple-data execution as well as significant constraints on memory accesses. To bring the full power of GPUs to bear on plasma physics problems, we must adapt the computational methods to this new programming model. We have developed a GPU implementation of the particle-in-cell (PIC) method, one of the mainstays of plasma physics simulation. This framework is highly general and enables advanced PIC features such as high order particles and absorbing boundary conditions. The main elements of the PIC loop, including field interpolation and particle deposition, are designed to optimize memory access. We describe the performance of these algorithms and discuss some of the methods used. Work supported by DARPA contract W31P4Q-15-C-0061 (SBIR).

Detection of cancerous cervical cells using physical adhesion of fluorescent silica particles and centripetal force.

PubMed

Gaikwad, Ravi M; Dokukin, Maxim E; Iyer, K Swaminathan; Woodworth, Craig D; Volkov, Dmytro O; Sokolov, Igor

2011-04-07

Here we describe a non-traditional method to identify cancerous human cervical epithelial cells in a culture dish based on physical adhesion between silica beads and cells. It is a simple optical fluorescence-based technique which detects the relative difference in the amount of fluorescent silica beads physically adherent to surfaces of cancerous and normal cervical cells. The method utilizes the centripetal force gradient that occurs in a rotating culture dish. Due to the variation in the balance between adhesion and centripetal forces, cancerous and normal cells demonstrate clearly distinctive distributions of the fluorescent particles adherent to the cell surface over the culture dish. The method demonstrates higher adhesion of silica particles to normal cells compared to cancerous cells. The difference in adhesion was initially observed by atomic force microscopy (AFM). The AFM data were used to design the parameters of the rotational dish experiment. The optical method that we describe is much faster and technically simpler than AFM. This work provides proof of the concept that physical interactions can be used to accurately discriminate normal and cancer cells. © The Royal Society of Chemistry 2011

Relativity, Symmetry, and the Structure of Quantum Theory, Volume 2; Point form relativistic quantum mechanics

NASA Astrophysics Data System (ADS)

Klink, William H.; Schweiger, Wolfgang

2018-03-01

This book covers relativistic quantum theory from the point of view of a particle theory, based on the irreducible representations of the Poincaré group, the group that expresses the symmetry of Einstein relativity. There are several ways of formulating such a theory; this book develops what is called relativistic point form quantum mechanics, which, unlike quantum field theory, deals with a fixed number of particles in a relativistically invariant way. A chapter is devoted to applications of point form quantum mechanics to nuclear physics.

Time?

NASA Astrophysics Data System (ADS)

Amoroso, Richard L.

2013-09-01

The concept of time in the `clockwork' Newtonian world was irrelevant; and has generally been ignored until recently by several generations of physicists since the implementation of quantum mechanics. We will set aside the utility of time as a property relating to physical calculations of events relating to a metrics line element or as an aspect of the transformation of a particles motion/interaction in a coordinate system or in relation to thermodynamics etc., i.e. we will discard all the usual uses of time as a concept used to circularly define physical parameters in terms of other physical parameters; concentrating instead on time as an aspect of the fundamental cosmic topology of our virtual reality especially as it inseparably relates to the nature and role of the observer in natural science.

Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

NASA Astrophysics Data System (ADS)

Plionis, A. A.; Peterson, D. S.; Tandon, L.; LaMont, S. P.

2010-03-01

Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

Fluid casting of particle-based articles

DOEpatents

Menchhofer, P.

1995-03-28

A method is disclosed for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product. 1 figure.

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.

Key Role of Nitrate in Phase Transitions of Urban Particles: Implications of Important Reactive Surfaces for Secondary Aerosol Formation

NASA Astrophysics Data System (ADS)

Sun, Jiaxing; Liu, Lei; Xu, Liang; Wang, Yuanyuan; Wu, Zhijun; Hu, Min; Shi, Zongbo; Li, Yongjie; Zhang, Xiaoye; Chen, Jianmin; Li, Weijun

2018-01-01

Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS-AN containing haze particles. Here hygroscopic properties of laboratory-generated AS-AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS-AN particles showed a two-stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid-aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60-80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity-dependent phase transitions of nitrate-abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air.

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

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.

Mobilization and transport of metal-rich colloidal particles from mine tailings into soil under transient chemical and physical conditions.

PubMed

Lu, Cong; Wu, Yaoguo; Hu, Sihai; Raza, Muhammad Ali; Fu, Yilin

2016-04-01

Exposed mine tailing wastes with considerable heavy metals can release hazardous colloidal particles into soil under transient chemical and physical conditions. Two-layered packed columns with tailings above and soils below were established to investigate mobilization and transport of colloidal particles from metal-rich mine tailings into soil under transient infiltration ionic strength (IS: 100, 20, 2 mM) and flow rate (FR: 20.7, 41, and 62.3 mm h(-1)), with Cu and Pb as representatives of the heavy metals. Results show that the tailing particles within the colloidal size (below 2 μm) were released from the columns. A step-decrease in infiltration IS and FR enhanced, whereas a step-increase in the IS and FR restrained the release of tailing particles from the column. The effects of step-changing FR were unexpected due to the small size of the released tailing particles (220-342 nm, being not sensitive to hydrodynamic shear force), the diffusion-controlled particle release process and the relatively compact pore structure. The tailing particles present in the solution with tested IS were found negatively charged and more stable than soil particles, which provides favorable conditions for tailing particles to be transported over a long distance in the soil. The mobilization and transport of Cu and Pb from the tailings into soil were mediated by the tailing particles. Therefore, the inherent toxic tailing particles could be considerably introduced into soil under certain conditions (IS reduction or FR decrease), which may result in serious environmental pollution.

The feasibility of using explicit method for linear correction of the particle size variation using NIR Spectroscopy combined with PLS2regression method

NASA Astrophysics Data System (ADS)

Yulia, M.; Suhandy, D.

2018-03-01

NIR spectra obtained from spectral data acquisition system contains both chemical information of samples as well as physical information of the samples, such as particle size and bulk density. Several methods have been established for developing calibration models that can compensate for sample physical information variations. One common approach is to include physical information variation in the calibration model both explicitly and implicitly. The objective of this study was to evaluate the feasibility of using explicit method to compensate the influence of different particle size of coffee powder in NIR calibration model performance. A number of 220 coffee powder samples with two different types of coffee (civet and non-civet) and two different particle sizes (212 and 500 µm) were prepared. Spectral data was acquired using NIR spectrometer equipped with an integrating sphere for diffuse reflectance measurement. A discrimination method based on PLS-DA was conducted and the influence of different particle size on the performance of PLS-DA was investigated. In explicit method, we add directly the particle size as predicted variable results in an X block containing only the NIR spectra and a Y block containing the particle size and type of coffee. The explicit inclusion of the particle size into the calibration model is expected to improve the accuracy of type of coffee determination. The result shows that using explicit method the quality of the developed calibration model for type of coffee determination is a little bit superior with coefficient of determination (R2) = 0.99 and root mean square error of cross-validation (RMSECV) = 0.041. The performance of the PLS2 calibration model for type of coffee determination with particle size compensation was quite good and able to predict the type of coffee in two different particle sizes with relatively high R2 pred values. The prediction also resulted in low bias and RMSEP values.

Changes in concepts of time from Aristotle to Einstein

NASA Astrophysics Data System (ADS)

Sachs, Mendel

1996-03-01

The meaning of time and motion is discussed, at first tracing conceptual changes from Aristotle to Galileo/Newton to Einstein. Different views of ‘time’ in 20th century physics are then examined, with primary focus on the revolutionary changes that came with the theory of general relativity. Implications of its new view in all domains of physics are discussed — from elementary particles to cosmology. The special role of Hamilton's quaternion calculus in equations of motion in general relativity is shown.

Another look through Heisenberg’s microscope

NASA Astrophysics Data System (ADS)

Boughn, Stephen; Reginatto, Marcel

2018-05-01

Heisenberg introduced his famous uncertainty relations in a seminal 1927 paper entitled The Physical Content of Quantum Kinematics and Mechanics. He motivated his arguments with a gedanken experiment, a gamma ray microscope to measure the position of a particle. A primary result was that, due to the quantum nature of light, there is an inherent uncertainty in the determinations of the particle’s position and momentum dictated by an indeterminacy relation, δ qδ p∼ h. Heisenberg offered this demonstration as ‘a direct physical interpretation of the [quantum mechanical] equation {{pq}}-{{qp}}=-{{i}}{\\hslash }’ but considered the indeterminacy relation to be much more than this. He also argued that it implies limitations on the very meanings of position and momentum and emphasised that these limitations are the source of the statistical character of quantum mechanics. In addition, Heisenberg hoped but was unable to demonstrate that the laws of quantum mechanics could be derived directly from the uncertainty relation. In this paper, we revisit Heisenberg’s microscope and argue that the Schrödinger equation for a free particle does indeed follow from the indeterminacy relation together with reasonable statistical assumptions.

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.

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

Effect of plasma spray processing variations on particle melting and splat spreading of hydroxylapatite and alumina

NASA Astrophysics Data System (ADS)

Yankee, S. J.; Pletka, B. J.

1993-09-01

Splats of hydroxylapatite (HA) and alumina were obtained via plasma spraying using systematically varied combinations of plasma velocity and temperature, which were achieved by altering the primary plasma gas flow rate and plasma gas composition. Particle size was also varied in the case of alumina. Splat spreading was quantified via computer- aided image analysis as a function of processing variations. A comparison of the predicted splat dimensions from a model developed by Madejski with experimental observations of HA and alumina splats was performed. The model tended to underestimate the HA splat sizes, suggesting that evaporation of smaller particles occurred under the chosen experimental conditions, and to overestimate the observed alumina splat dimensions. Based on this latter result and on the surface appearance of the substrates, incomplete melting appeared to take place in all but the smaller alumina particles. Analysis of the spreading data as a function of the processing variations indicated that the particle size as well as the plasma temperature and velocity influenced the extent of particle melting. Based on these data and other considerations, a physical model was developed that described the degree of particle melting in terms of material and processing parameters. The physical model correctly predicted the relative splat spreading behavior of HA and alumina, assuming that spreading was directly linked to the extent of particle melting.

Properties of carbonate rocks related to SO2 reactivity

USGS Publications Warehouse

Borgwardt, R.H.; Harvey, R.D.

1972-01-01

Petrographic examination and grain size-distribution measurements were made on 11 specimens representing a broad spectrum of limestones and dolomites. The SO2 reaction kinetics of calcines prepared from each rock type were determined at 980??C. Stones of various geological types yield calcines of distinctly different physical structures that show correspondingly large differences in both rate of reaction and capacity for SO2 sorption. Pore size and particle size together determine the extent to which the interiors of individual particles react. Particles smaller than 0.01 cm with pores larger than 0.1 ?? react throughout their internal pore structure at a rate directly proportional to the BET surface. The rate decays exponentially as sulfation proceeds until the pores are filled with reaction product. The ultimate capacity of small particles is determined by the pore volume available for product accumulation, which is generally equivalent to about 50% conversion of the CaO in limestones. Variations in effectiveness of carbonate rocks for flue gas desulfurization are explained by the physical properties of their calcines, which are related to the crystal structure of the original rock. The high reaction rates achieved in the limestone injection process apparently result from the large surface area existing for short periods immediately following the dissociation of CaCO3.

Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles.

PubMed

Sawakuchi, Gabriel O; Yukihara, Eduardo G

2012-01-21

The objective of this work is to test analytical models to calculate the luminescence efficiency of Al(2)O(3):C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced by the heavy charged particle. We compared the relative luminescence efficiency calculated using seven different radial dose distribution models, including a modified model introduced in this work, with experimental data. The results obtained using the modified radial dose distribution function agreed within 20% with experimental data from Al(2)O(3):C OSLDs relative luminescence efficiency for particles with atomic number ranging from 1 to 54 and linear energy transfer in water from 0.2 up to 1368 keV µm(-1). In spite of the significant improvement over other radial dose distribution models, understanding of the underlying physical processes associated with these radial dose distribution models remain elusive and may represent a limitation of the track structure model.

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

Supergravity and the Unification of the Laws of Physics

ERIC Educational Resources Information Center

Freedman, Daniel Z.; van Nieuwenhuizen, Peter

1978-01-01

In this new theory the gravitational force arises from a symmetry relating particles with vastly different properties. The ultimate result may be a unified theory of all the basic forces in nature. (Author/BB)

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

Particle rings and astrophysical accretion discs

NASA Astrophysics Data System (ADS)

Lovelace, R. V. E.; Romanova, M. M.

2016-03-01

Norman Rostoker had a wide range of interests and significant impact on the plasma physics research at Cornell during the time he was a Cornell professor. His interests ranged from the theory of energetic electron and ion beams and strong particle rings to the related topics of astrophysical accretion discs. We outline some of the topics related to rings and discs including the Rossby wave instability which leads to formation of anticyclonic vortices in astrophysical discs. These vorticies are regions of high pressure and act to trap dust particles which in turn may facilitate planetesimals growth in proto-planetary disks and could be important for planet formation. Analytical methods and global 3D magneto-hydrodynamic simulations have led to rapid advances in our understanding of discs in recent years.

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

Giudice, Gian F.; McCullough, Matthew; Urbano, Alfredo

The LIGO observation of gravitational waves from a binary black hole merger has begun a new era in fundamental physics. If new dark sector particles, be they bosons or fermions, can coalesce into exotic compact objects (ECOs) of astronomical size, then the first evidence for such objects, and their underlying microphysical description, may arise in gravitational wave observations. In this work we study how the macroscopic properties of ECOs are related to their microscopic properties, such as dark particle mass and couplings. We then demonstrate the smoking gun exotic signatures that would provide observational evidence for ECOs, and hence newmore » particles, in terrestrial gravitational wave observatories. Finally, we discuss how gravitational waves can test a core concept in general relativity: Hawking’s area theorem.« less

Advancing the understanding of plasma transport in mid-size stellarators

NASA Astrophysics Data System (ADS)

Hidalgo, Carlos; Talmadge, Joseph; Ramisch, Mirko; TJ-II, the; HXS; TJ-K Teams

2017-01-01

The tokamak and the stellarator are the two main candidate concepts for magnetically confining fusion plasmas. The flexibility of the mid-size stellarator devices together with their unique diagnostic capabilities make them ideally suited to study the relation between magnetic topology, electric fields and transport. This paper addresses advances in the understanding of plasma transport in mid-size stellarators with an emphasis on the physics of flows, transport control, impurity and particle transport and fast particles. The results described here emphasize an improved physics understanding of phenomena in stellarators that complements the empirical approach. Experiments in mid-size stellarators support the development of advanced plasma scenarios in Wendelstein 7-X (W7-X) and, in concert with better physics understanding in tokamaks, may ultimately lead to an advance in the prediction of burning plasma behaviour.

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.

GRAVITATIONAL ACCRETION OF PARTICLES ONTO MOONLETS EMBEDDED IN SATURN's RINGS

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

Yasui, Yuki; Ohtsuki, Keiji; Daisaka, Hiroshi, E-mail: y.yasui@whale.kobe-u.ac.jp, E-mail: ohtsuki@tiger.kobe-u.ac.jp

2014-12-20

Using a local N-body simulation, we examine gravitational accretion of ring particles onto moonlet cores in Saturn's rings. We find that gravitational accretion of particles onto moonlet cores is unlikely to occur in the C ring and probably difficult in the inner B ring as well provided that the cores are rigid water ice. Dependence of particle accretion on ring thickness changes when the radial distance from the planet and/or the density of particles is varied: the former determines the size of the core's Hill radius relative to its physical size, while the latter changes the effect of self-gravity ofmore » accreted particles. We find that particle accretion onto high-latitude regions of the core surface can occur even if the rings' vertical thickness is much smaller than the core radius, although redistribution of particles onto the high-latitude regions would not be perfectly efficient in outer regions of the rings such as the outer A ring, where the size of the core's Hill sphere in the vertical direction is significantly larger than the core's physical radius. Our results suggest that large boulders recently inferred from observations of transparent holes in the C ring are not formed locally by gravitational accretion, while propeller moonlets in the A ring would be gravitational aggregates formed by particle accretion onto dense cores. Our results also imply that the main bodies of small satellites near the outer edge of Saturn's rings may have been formed in rather thin rings.« less

R&D of the CEPC scintillator-tungsten ECAL

NASA Astrophysics Data System (ADS)

Dong, M. Y.

2018-03-01

The circular electron and positron collider (CEPC) was proposed as a future Higgs factory. To meet the physics requirements, a particle flow algorithm-oriented calorimeter system with high energy resolution and precise reconstruction is considered. A sampling calorimeter with scintillator-tungsten sandwich structure is selected as one of the electromagnetic calorimeter (ECAL) options due to its good performance and relatively low cost. We present the design, the test and the optimization of the scintillator module read out by silicon photomultiplier (SiPM), including the design and the development of the electronics. To estimate the performance of the scintillator and SiPM module for particles with different energy, the beam test of a mini detector prototype without tungsten shower material was performed at the E3 beams in Institute of High Energy Physics (IHEP). The results are consistent with the expectation. These studies provide a reference and promote the development of particle flow electromagnetic calorimeter for the CEPC.

Heat transfer from nanoparticles: a corresponding state analysis.

PubMed

Merabia, Samy; Shenogin, Sergei; Joly, Laurent; Keblinski, Pawel; Barrat, Jean-Louis

2009-09-08

In this contribution, we study situations in which nanoparticles in a fluid are strongly heated, generating high heat fluxes. This situation is relevant to experiments in which a fluid is locally heated by using selective absorption of radiation by solid particles. We first study this situation for different types of molecular interactions, using models for gold particles suspended in octane and in water. As already reported in experiments, very high heat fluxes and temperature elevations (leading eventually to particle destruction) can be observed in such situations. We show that a very simple modeling based on Lennard-Jones (LJ) interactions captures the essential features of such experiments and that the results for various liquids can be mapped onto the LJ case, provided a physically justified (corresponding state) choice of parameters is made. Physically, the possibility of sustaining very high heat fluxes is related to the strong curvature of the interface that inhibits the formation of an insulating vapor film.

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.

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.

Interaction of Burning Metal Particles

NASA Technical Reports Server (NTRS)

Dreizin, Edward L.; Berman, Charles H.; Hoffmann, Vern K.

1999-01-01

Physical characteristics of the combustion of metal particle groups have been addressed in this research. The combustion behavior and interaction effects of multiple metal particles has been studied using a microgravity environment, which presents a unique opportunity to create an "aerosol" consisting of relatively large particles, i.e., 50-300 m diameter. Combustion behavior of such an aerosol could be examined using methods adopted from well-developed single particle combustion research. The experiment included fluidizing relatively large (order of 100 m diameter) uniform metal particles under microgravity and igniting such an "aerosol" using a hot wire igniter. The flame propagation and details of individual particle combustion and particle interaction have been studied using a high speed movie and video-imaging with cameras coupled with microscope lenses to resolve individual particles. Interference filters were used to separate characteristic metal and metal oxide radiation bands from the thermal black body radiation. Recorded flame images were digitized and various image processing techniques including flame position tracking, color separation, and pixel by pixel image comparison were employed to understand the processes occurring in the burning aerosol. The development of individual particle flames, merging or separation, and extinguishment as well as induced particle motion have been analyzed to identify the mechanisms governing these processes. Size distribution, morphology, and elemental compositions of combustion products were characterized and used to link the observed in this project aerosol combustion phenomena with the recently expanded mechanism of single metal particle combustion.

Physics through the 1990s: Gravitation, cosmology and cosmic-ray physics

NASA Technical Reports Server (NTRS)

1986-01-01

The volume contains recommendations for space-and ground-based programs in gravitational physics, cosmology, and cosmic-ray physics. The section on gravitation examines current and planned experimental tests of general relativity; the theory behind, and search for, gravitational waves, including sensitive laser-interferometric tests and other observations; and advances in gravitation theory (for example, incorporating quantum effects). The section on cosmology deals with the big-bang model, the standard model from elementary-particle theory, the inflationary model of the Universe. Computational needs are presented for both gravitation and cosmology. Finally, cosmic-ray physics theory (nucleosynthesis, acceleration models, high-energy physics) and experiment (ground and spaceborne detectors) are discussed.

Review of Particle Physics

NASA Astrophysics Data System (ADS)

Patrignani, C.; Particle Data Group

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, Probability and Statistics. Among the 117 reviews are many that are new or heavily revised, including those on Pentaquarks and Inflation. The complete Review is published online in a journal and on the website of the Particle Data Group (http://pdg.lbl.gov). The printed PDG Book contains the Summary Tables and all review articles but no longer includes the detailed tables from the Particle Listings. A Booklet with the Summary Tables and abbreviated versions of some of the review articles is also available. Contents Abstract, Contributors, Highlights and Table of ContentsAcrobat PDF (150 KB) IntroductionAcrobat PDF (456 KB) Particle Physics Summary Tables Gauge and Higgs bosonsAcrobat PDF (155 KB) LeptonsAcrobat PDF (134 KB) QuarksAcrobat PDF (84 KB) MesonsAcrobat PDF (871 KB) BaryonsAcrobat PDF (300 KB) Searches (Supersymmetry, Compositeness, etc.)Acrobat PDF (91 KB) Tests of conservation lawsAcrobat PDF (330 KB) Reviews, Tables, and Plots Detailed contents for this sectionAcrobat PDF (37 KB) Constants, Units, Atomic and Nuclear PropertiesAcrobat PDF (278 KB) Standard Model and Related TopicsAcrobat PDF (7.3 MB) Astrophysics and CosmologyAcrobat PDF (2.7 MB) Experimental Methods and CollidersAcrobat PDF (3.8 MB) Mathematical Tools or Statistics, Monte Carlo, Group Theory Acrobat PDF (1.3 MB) Kinematics, Cross-Section Formulae, and PlotsAcrobat PDF (3.9 MB) Particle Listings Illustrative key and abbreviationsAcrobat PDF (235 KB) Gauge and Higgs bosonsAcrobat PDF (2 MB) LeptonsAcrobat PDF (1.5 MB) QuarksAcrobat PDF (1.2 MB) Mesons: Light unflavored and strangeAcrobat PDF (4 MB) Mesons: Charmed and bottomAcrobat PDF (7.4 MB) Mesons: OtherAcrobat PDF (3.1 MB) BaryonsAcrobat PDF (3.97 MB) Miscellaneous searchesAcrobat PDF (2.4 MB) IndexAcrobat PDF (160 KB)

Modes of occurrence of potentially hazardous elements in coal: levels of confidence

USGS Publications Warehouse

Finkelman, R.B.

1994-01-01

The modes of occurrence of the potentially hazardous elements in coal will be of significance in any attempt to reduce their mobilization due to coal combustion. Antimony and selenium may be present in solid solution in pyrite, as minute accessory sulfides dispersed throughout the organic matrix, or in organic association. Because of these modes of occurrence it is anticipated that less than 50% of these elements will be routinely removed by conventional coal cleaning procedures. Arsenic and mercury occur primarily in late-stage coarse-grained pyrite therefore physical coal cleaning procedures should be successful in removing substantial proportions of these elements. Cadmium occurs in sphalerite and lead in galena. Both of these minerals exhibit a wide range of particle sizes and textural relations. Depending on the particle size and textural relations, physical coal cleaning may remove as little as 25% of these elements or as much as 75%. Manganese in bituminous coal occurs in carbonates, especially siderite. Physical coal cleaning should remove a substantial proportion of this element. More information is needed to elucidate the modes of occurrence of beryllium, chromium, cobalt, and nickel. ?? 1994.

Nonlinear theory of diffusive acceleration of particles by shock waves

NASA Astrophysics Data System (ADS)

Malkov, M. A.; Drury, L. O'C.

2001-04-01

Among the various acceleration mechanisms which have been suggested as responsible for the nonthermal particle spectra and associated radiation observed in many astrophysical and space physics environments, diffusive shock acceleration appears to be the most successful. We review the current theoretical understanding of this process, from the basic ideas of how a shock energizes a few reactionless particles to the advanced nonlinear approaches treating the shock and accelerated particles as a symbiotic self-organizing system. By means of direct solution of the nonlinear problem we set the limit to the test-particle approximation and demonstrate the fundamental role of nonlinearity in shocks of astrophysical size and lifetime. We study the bifurcation of this system, proceeding from the hydrodynamic to kinetic description under a realistic condition of Bohm diffusivity. We emphasize the importance of collective plasma phenomena for the global flow structure and acceleration efficiency by considering the injection process, an initial stage of acceleration and, the related aspects of the physics of collisionless shocks. We calculate the injection rate for different shock parameters and different species. This, together with differential acceleration resulting from nonlinear large-scale modification, determines the chemical composition of accelerated particles. The review concentrates on theoretical and analytical aspects but our strategic goal is to link the fundamental theoretical ideas with the rapidly growing wealth of observational data.

Exact symmetries in the velocity fluctuations of a hot Brownian swimmer

NASA Astrophysics Data System (ADS)

Falasco, Gianmaria; Pfaller, Richard; Bregulla, Andreas P.; Cichos, Frank; Kroy, Klaus

2016-09-01

Symmetries constrain dynamics. We test this fundamental physical principle, experimentally and by molecular dynamics simulations, for a hot Janus swimmer operating far from thermal equilibrium. Our results establish scalar and vectorial steady-state fluctuation theorems and a thermodynamic uncertainty relation that link the fluctuating particle current to its entropy production at an effective temperature. A Markovian minimal model elucidates the underlying nonequilibrium physics.

Spatial Variability of Organic Carbon in a Fractured Mudstone and Its Effect on the Retention and Release of Trichloroethene (TCE)

NASA Astrophysics Data System (ADS)

Sole-Mari, G.; Fernandez-Garcia, D.

2016-12-01

Random Walk Particle Tracking (RWPT) coupled with Kernel Density Estimation (KDE) has been recently proposed to simulate reactive transport in porous media. KDE provides an optimal estimation of the area of influence of particles which is a key element to simulate nonlinear chemical reactions. However, several important drawbacks can be identified: (1) the optimal KDE method is computationally intensive and thereby cannot be used at each time step of the simulation; (2) it does not take advantage of the prior information about the physical system and the previous history of the solute plume; (3) even if the kernel is optimal, the relative error in RWPT simulations typically increases over time as the particle density diminishes by dilution. To overcome these problems, we propose an adaptive branching random walk methodology that incorporates the physics, the particle history and maintains accuracy with time. The method allows particles to efficiently split and merge when necessary as well as to optimally adapt their local kernel shape without having to recalculate the kernel size. We illustrate the advantage of the method by simulating complex reactive transport problems in randomly heterogeneous porous media.

A new mechanism for relativistic particle acceleration via wave-particle interaction

NASA Astrophysics Data System (ADS)

Lapenta, Giovanni; Markidis, Stefano; Marocchino, Alberto

2006-10-01

Often in laboratory, space and astrophysical plasma, high energy populations are observed. Two puzzling factors still defy our understanding. First, such populations of high energy particles produce power law distributions that are not only ubiquitous but also persistent in time. Such persistence is in direct contradiction to the H theorem that states the ineluctable transition of physical systems towards thermodynamic equilibrium, and ergo Maxwellian distributions. Second, such high energy populations are efficiently produced, much more efficiently than processes that we know can produce. A classic example of such a situation is cosmic rays where power alws extend up to tremendolus energy ranges. In the present work, we identify a new mechanism for particle acceleration via wave-particle interaction. The mechanism is peculiar to special relativity and has no classical equivalent. That explains why it is not observed in most simulation studies of plasma processes, based on classical physics. The mechanism is likely to be active in systems undergoing streaming instabilities and in particular shocked systems. The new mechanism can produce energy increases vastly superior to previously known mechanisms (such as Fermi acceleration) and can hold the promise of explaining at least some of the observed power laws.

Locally adaptive methods for KDE-based random walk models of reactive transport in porous media

NASA Astrophysics Data System (ADS)

Sole-Mari, G.; Fernandez-Garcia, D.

2017-12-01

Random Walk Particle Tracking (RWPT) coupled with Kernel Density Estimation (KDE) has been recently proposed to simulate reactive transport in porous media. KDE provides an optimal estimation of the area of influence of particles which is a key element to simulate nonlinear chemical reactions. However, several important drawbacks can be identified: (1) the optimal KDE method is computationally intensive and thereby cannot be used at each time step of the simulation; (2) it does not take advantage of the prior information about the physical system and the previous history of the solute plume; (3) even if the kernel is optimal, the relative error in RWPT simulations typically increases over time as the particle density diminishes by dilution. To overcome these problems, we propose an adaptive branching random walk methodology that incorporates the physics, the particle history and maintains accuracy with time. The method allows particles to efficiently split and merge when necessary as well as to optimally adapt their local kernel shape without having to recalculate the kernel size. We illustrate the advantage of the method by simulating complex reactive transport problems in randomly heterogeneous porous media.

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)

Plato's TIMAIOσ (TIMAEUS) and Modern Particle Physics

NASA Astrophysics Data System (ADS)

Machleidt, Ruprecht

2005-04-01

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

Exact Descriptions of General Relativity Derived from Newtonian Mechanics within Curved Geometries

NASA Astrophysics Data System (ADS)

Savickas, David

2015-04-01

General relativity and Newtonian mechanics are shown to be exactly related when Newton's second law is written in a curved geometry by using the physical components of a vector as is defined in tensor calculus. By replacing length within the momentum's velocity by the vector metric in a curved geometry the second law can then be shown to be exactly identical to the geodesic equation of motion occurring in general relativity. When time's vector direction is constant, as similarly occurs in Newtonian mechanics, this equation can be reduced to a curved three-dimensional equation of motion that yields the the Schwarzschild equations of motion for an isolated particle. They can be used to describe gravitational behavior for any array of masses for which the Newtonian gravitational potential is known, and is shown to describe a mass particle's behavior in the gravitational field of a thin mass-rod. This use of Newton's laws allows relativistic behavior to be described in a physically comprehensible manner. D. Savickas, Int. J. Mod. Phys. D 23 1430018, (2014).

Ice nucleation activity of diesel soot particles at cirrus relevant temperature conditions: Effects of hydration, secondary organics coating, soot morphology, and coagulation

NASA Astrophysics Data System (ADS)

Kulkarni, Gourihar; China, Swarup; Liu, Shang; Nandasiri, Manjula; Sharma, Noopur; Wilson, Jacqueline; Aiken, Allison C.; Chand, Duli; Laskin, Alexander; Mazzoleni, Claudio; Pekour, Mikhail; Shilling, John; Shutthanandan, Vaithiyalingam; Zelenyuk, Alla; Zaveri, Rahul A.

2016-04-01

Ice formation by diesel soot particles was investigated at temperatures ranging from -40 to -50°C. Size-selected soot particles were physically and chemically aged in an environmental chamber, and their ice nucleating properties were determined using a continuous flow diffusion type ice nucleation chamber. Bare (freshly formed), hydrated, and compacted soot particles, as well as α-pinene secondary organic aerosol (SOA)-coated soot particles at high relative humidity conditions, showed ice formation activity at subsaturation conditions with respect to water but below the homogeneous freezing threshold conditions. However, SOA-coated soot particles at dry conditions were observed to freeze at homogeneous freezing threshold conditions. Overall, our results suggest that heterogeneous ice nucleation activity of freshly emitted diesel soot particles are sensitive to some of the aging processes that soot can undergo in the atmosphere.

Numerical Simulation of Transitional, Hypersonic Flows using a Hybrid Particle-Continuum Method

NASA Astrophysics Data System (ADS)

Verhoff, Ashley Marie

Analysis of hypersonic flows requires consideration of multiscale phenomena due to the range of flight regimes encountered, from rarefied conditions in the upper atmosphere to fully continuum flow at low altitudes. At transitional Knudsen numbers there are likely to be localized regions of strong thermodynamic nonequilibrium effects that invalidate the continuum assumptions of the Navier-Stokes equations. Accurate simulation of these regions, which include shock waves, boundary and shear layers, and low-density wakes, requires a kinetic theory-based approach where no prior assumptions are made regarding the molecular distribution function. Because of the nature of these types of flows, there is much to be gained in terms of both numerical efficiency and physical accuracy by developing hybrid particle-continuum simulation approaches. The focus of the present research effort is the continued development of the Modular Particle-Continuum (MPC) method, where the Navier-Stokes equations are solved numerically using computational fluid dynamics (CFD) techniques in regions of the flow field where continuum assumptions are valid, and the direct simulation Monte Carlo (DSMC) method is used where strong thermodynamic nonequilibrium effects are present. Numerical solutions of transitional, hypersonic flows are thus obtained with increased physical accuracy relative to CFD alone, and improved numerical efficiency is achieved in comparison to DSMC alone because this more computationally expensive method is restricted to those regions of the flow field where it is necessary to maintain physical accuracy. In this dissertation, a comprehensive assessment of the physical accuracy of the MPC method is performed, leading to the implementation of a non-vacuum supersonic outflow boundary condition in particle domains, and more consistent initialization of DSMC simulator particles along hybrid interfaces. The relative errors between MPC and full DSMC results are greatly reduced as a direct result of these improvements. Next, a new parameter for detecting rotational nonequilibrium effects is proposed and shown to offer advantages over other continuum breakdown parameters, achieving further accuracy gains. Lastly, the capabilities of the MPC method are extended to accommodate multiple chemical species in rotational nonequilibrium, each of which is allowed to equilibrate independently, enabling application of the MPC method to more realistic atmospheric flows.

NEWS: TRUMP resources

NASA Astrophysics Data System (ADS)

Swinbank, Elizabeth

2000-05-01

Support for astronomy in A-level physics aslogo Help is at hand for teachers and students choosing astronomy as part of A-level physics. The Teaching Resources Unit for Modern Physics (TRUMP) has produced a resource package covering all the astronomical options in the Edexcel, OCR and AQA (NEAB) syllabuses. The forerunner to TRUMP was the project that produced the highly successful Particle Physics Pack, sponsored by the Institute of Physics, which was instrumental in introducing particle physics into A-level syllabuses. The TRUMP Astrophysics Resource Package fills a gap between the colourful stimulus of popular materials on the one hand, and professional texts on the other. But this is not just another A-level textbook; the six-part resource pack has a similar structure and purpose to the Particle Physics Pack. It provides over 400 pages of comprehensive information for teachers, building on their existing subject knowledge and bringing them up to date as well as giving suggestions for teaching and notes on syllabus coverage. The package includes nearly 40 photocopiable sheets for students. The emphasis is on the physics that underpins the astronomy. There are details of student activities requiring no specialist equipment beyond that normally found in A-level labs, exercises using authentic data, and plenty of questions (all with worked solutions). The development of the TRUMP Astrophysics Package was funded by the Nuffield Foundation, the Particle Physics and Astronomy Research Council, the Institute of Physics and York University. The package is available by mail order, price £48 (inc. UK p&p) from the TRUMP Project, Science Education Group, University of York, Heslington, York YO10 5DD. Some parts may be purchased separately; for details contact the project's director, Elizabeth Swinbank (tel: 01904 434537, fax: 01904 434078, e-mail: es14@york.ac.uk) or consult the web page www.york.ac.uk/org/seg/trump. The BaBar experiment balogo In the spring of 1999, scientists began to collect data from the BaBar experiment - an international collaboration involving the UK, several other European countries and the USA. The experiment is designed to throw light on the puzzling question of why there is so little antimatter in the universe and so much matter. The TRUMP BaBar resource package brings the mystery of antimatter into schools. There are notes and colourful posters on the physics of BaBar, and photocopiable sheets supporting student activities. These include explorations of symmetry, templates for making a scale model of the BaBar detector, and a web-based research project. The pack is designed mainly for A-level physics (particularly those courses that include some particle physics) but parts also relate to GCSE science, Scottish Higher physics and Standard physics. The BaBar resource package is available free from the Particle Physics and Astronomy Research Council, which fully funded its development and production. Contact the Publicity Team, PPARC, Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1SZ (tel: 01973 442123, e-mail: pr_pus@pparc.ac.uk).

Relations between morning sector Pi 1 pulsation activity and particle and field characteristics observed by the DE 2 satellite

NASA Technical Reports Server (NTRS)

Engebretson, M. J.; Cahill, L. J., Jr.; Winningham, J. D.; Rosenberg, T. J.; Arnoldy, R. L.; Maynard, N. C.; Sugiura, M.

1986-01-01

Ground-based magnetometer, photometer, and riometer data are combined with low-altitude particle and electric and magnetic field data from the DE-2 spacecraft to provide a more complete characterization of the magnetospheric and tropospheric environment in which morning sector asymmetric Pi 1 pulsations are observed. The results of the study are in agreement with recent conclusions that morning sector asymmetric Pi 1 pulsations are physically related to pulsating aurorae. Precipitation of energetic electrons (E greater than 35 keV) coincides in every instance with the occurrence of these pulsations.

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…

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.

Dust coagulation in ISM

NASA Technical Reports Server (NTRS)

Chokshi, Arati; Tielens, Alexander G. G. M.; Hollenbach, David

1989-01-01

Coagulation is an important mechanism in the growth of interstellar and interplanetary dust particles. The microphysics of the coagulation process was theoretically analyzed as a function of the physical properties of the coagulating grains, i.e., their size, relative velocities, temperature, elastic properties, and the van der Waal interaction. Numerical calculations of collisions between linear chains provide the wave energy in individual particles and the spectrum of the mechanical vibrations set up in colliding particles. Sticking probabilities are then calculated using simple estimates for elastic deformation energies and for the attenuation of the wave energy due to absorption and scattering processes.

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.

The growth of astrophysical understanding

NASA Astrophysics Data System (ADS)

Harwit, Martin

2011-06-01

Since this symposium commemorated Galileo's discoveries and was concerned with astronomy and culture, I thought I might examine the extent to which culture affects how we view, depict, and ultimately come to understand the Universe around us. Twenty-five years ago, Andrew Pickering, wrote Constructing Quarks - A Sociological History of Particle Physics, (Pickering 1984) a book that enormously annoyed the high-energy physics community, perhaps because it contained a disquieting dose of truth. Pickering argued that the theory of fundamental particles, the particles that make up the atomic nucleus, and break up or fuse into myriad other particles when smashed into each other, was a construct that physicist had pieced together, through a process he termed a ``communally congenial representation of reality''. Physicists, he claimed, had arrived at a so-called ``standard theory'' of particle physics that was not an inherent description of Nature, but ``deeply rooted in common-sense intuitions about the world and our knowledge of it''. Instead, Pickering surmised that a better depiction of particle physics would eventually be found, which would appear unrecognizably different from what had come to be the accepted way of viewing Nature's fundamental particles. Today, many particle physicists would be more likely to agree with Pickering than they were then. Although the standard theory has successfully survived a quarter of a century of testing, its scope is known to be limited. It fails to properly accommodate gravity. And the string theories, brane theories, and other attempts of particle physicists to produce a coherent theory of all the known forces of nature have so different a structure from the standard theory, topologically, as well as in terms of numbers of spatial dimensions, that they share little recognizable resemblance. So, we may ask, was Pickering right? Are physicists and astronomers just constructing congenial representations that bear little relation to the inherent structure of the Universe we inhabit? In astronomy, we have by now embraced what we term the ``concordance model'' based on general relativity, which we assert has led to tremendous strides in understanding the evolution of the Universe. But we find ourselves forced to postulate a new form of matter, dark matter, the existence of which is supported by little independent evidence, and we find ourselves forced to postulate the existence of a new form of energy, dark energy, for which there is similarly little independent evidence. Perhaps both these postulates will someday soon be justified. But we may equally well find a need for viewing the Universe in a totally different way that encompasses general relativity only as a limiting case, but embraces dark matter and dark energy as a natural consequence. Such a depiction might then be just as mind-bogglingly different from what we conceive today, as Einstein's postulate was, when he first annunciated it, that the speed of light would always appear the same no matter how fast an observer was moving toward or away from its source. How could that be, it violated every conceivable human intuition?

Rapid MCNP simulation of DNA double strand break (DSB) relative biological effectiveness (RBE) for photons, neutrons, and light ions.

PubMed

Stewart, Robert D; Streitmatter, Seth W; Argento, David C; Kirkby, Charles; Goorley, John T; Moffitt, Greg; Jevremovic, Tatjana; Sandison, George A

2015-11-07

To account for particle interactions in the extracellular (physical) environment, information from the cell-level Monte Carlo damage simulation (MCDS) for DNA double strand break (DSB) induction has been integrated into the general purpose Monte Carlo N-particle (MCNP) radiation transport code system. The effort to integrate these models is motivated by the need for a computationally efficient model to accurately predict particle relative biological effectiveness (RBE) in cell cultures and in vivo. To illustrate the approach and highlight the impact of the larger scale physical environment (e.g. establishing charged particle equilibrium), we examined the RBE for DSB induction (RBEDSB) of x-rays, (137)Cs γ-rays, neutrons and light ions relative to γ-rays from (60)Co in monolayer cell cultures at various depths in water. Under normoxic conditions, we found that (137)Cs γ-rays are about 1.7% more effective at creating DSB than γ-rays from (60)Co (RBEDSB  =  1.017) whereas 60-250 kV x-rays are 1.1 to 1.25 times more efficient at creating DSB than (60)Co. Under anoxic conditions, kV x-rays may have an RBEDSB up to 1.51 times as large as (60)Co γ-rays. Fission neutrons passing through monolayer cell cultures have an RBEDSB that ranges from 2.6 to 3.0 in normoxic cells, but may be as large as 9.93 for anoxic cells. For proton pencil beams, Monte Carlo simulations suggest an RBEDSB of about 1.2 at the tip of the Bragg peak and up to 1.6 a few mm beyond the Bragg peak. Bragg peak RBEDSB increases with decreasing oxygen concentration, which may create opportunities to apply proton dose painting to help address tumor hypoxia. Modeling of the particle RBE for DSB induction across multiple physical and biological scales has the potential to aid in the interpretation of laboratory experiments and provide useful information to advance the safety and effectiveness of hadron therapy in the treatment of cancer.

Physics and biophysics experiments needed for improved risk assessment in space

NASA Astrophysics Data System (ADS)

Sihver, L.

To improve the risk assessment of radiation carcinogenesis, late degenerative tissue effects, acute syndromes, synergistic effects of radiation and microgravity or other spacecraft factors, and hereditary effects, on future LEO and interplanetary space missions, the radiobiological effects of cosmic radiation before and after shielding must be well understood. However, cosmic radiation is very complex and includes low and high LET components of many different neutral and charged particles. The understanding of the radiobiology of the heavy ions, from GCRs and SPEs, is still a subject of great concern due to the complicated dependence of their biological effects on the type of ion and energy, and its interaction with various targets both outside and within the spacecraft and the human body. In order to estimate the biological effects of cosmic radiation, accurate knowledge of the physics of the interactions of both charged and non-charged high-LET particles is necessary. Since it is practically impossible to measure all primary and secondary particles from all projectile-target-energy combinations needed for a correct risk assessment in space, accurate particle and heavy ion transport codes might be a helpful instrument to overcome those difficulties. These codes have to be carefully validated to make sure they fulfill preset accuracy criteria, e.g. to be able to predict particle fluence and energy distributions within a certain accuracy. When validating the accuracy of the transport codes, both space and ground-based accelerator experiments are needed. In this paper current and future physics and biophysics experiments needed for improved risk assessment in space will be discussed. The cyclotron HIRFL (heavy ion research facility in Lanzhou) and the new synchrotron CSR (cooling storage ring), which can be used to provide ion beams for space related experiments at the Institute of Modern Physics, Chinese Academy of Sciences (IMP-CAS), will be presented together with the physical and biomedical research performed at IMP-CAS.

Speed-limited particle-in-cell (SLPIC) simulation

NASA Astrophysics Data System (ADS)

Werner, Gregory; Cary, John; Jenkins, Thomas

2016-10-01

Speed-limited particle-in-cell (SLPIC) simulation is a new method for particle-based plasma simulation that allows increased timesteps in cases where the timestep is determined (e.g., in standard PIC) not by the smallest timescale of interest, but rather by an even smaller physical timescale that affects numerical stability. For example, SLPIC need not resolve the plasma frequency if plasma oscillations do not play a significant role in the simulation; in contrast, standard PIC must usually resolve the plasma frequency to avoid instability. Unlike fluid approaches, SLPIC retains a fully-kinetic description of plasma particles and includes all the same physical phenomena as PIC; in fact, if SLPIC is run with a PIC-compatible timestep, it is identical to PIC. However, unlike PIC, SLPIC can run stably with larger timesteps. SLPIC has been shown to be effective for finding steady-state solutions for 1D collisionless sheath problems, greatly speeding up computation despite a large ion/electron mass ratio. SLPIC is a relatively small modification of standard PIC, with no complexities that might degrade parallel efficiency (compared to PIC), and is similarly compatible with PIC field solvers and boundary conditions.

Inclined, collisional sediment transport

NASA Astrophysics Data System (ADS)

Berzi, Diego; Fraccarollo, Luigi

2013-10-01

We apply the constitutive relations of kinetic theory of granular gases to the transport of cohesionless sediments driven by a gravitational liquid turbulent stream in steady uniform conditions. The sediment-laden flow forms self-equilibrated mechanisms of resistance at the bed surface, below which the sediments are at rest. This geo-physical process takes place quite often in streams at moderate slope and may be interpreted through tools common to fluid mechanics and particle physics. Taking into account the viscous dissipation of the fluctuation energy of the particles, and using approximate methods of integration of the governing differential equations, permit to obtain a set of simple formulas for predicting how depths and flow rates adjust to the angle of inclination of the bed, without requiring additional tuning parameters besides the particle and fluid properties. The agreement with laboratory experiments performed with either plastic cylinders or gravel in water is remarkable. We also provide quantitative criteria to determine the range of validity of the theory, i.e., the values of the Shields number and the angle of inclination of the bed for which the particle stresses can be mostly ascribed to collisional exchange of momentum.

Gas-Grain Simulation Facility: Fundamental studies of particle formation and interactions. Volume 2: Abstracts, candidate experiments and feasibility study

NASA Technical Reports Server (NTRS)

Fogleman, Guy (Editor); Huntington, Judith L. (Editor); Schwartz, Deborah E. (Editor); Fonda, Mark L. (Editor)

1989-01-01

An overview of the Gas-Grain Simulation Facility (GGSF) project and its current status is provided. The proceedings of the Gas-Grain Simulation Facility Experiments Workshop are recorded. The goal of the workshop was to define experiments for the GGSF--a small particle microgravity research facility. The workshop addressed the opportunity for performing, in Earth orbit, a wide variety of experiments that involve single small particles (grains) or clouds of particles. Twenty experiments from the fields of exobiology, planetary science, astrophysics, atmospheric science, biology, physics, and chemistry were described at the workshop and are outlined in Volume 2. Each experiment description included specific scientific objectives, an outline of the experimental procedure, and the anticipated GGSF performance requirements. Since these experiments represent the types of studies that will ultimately be proposed for the facility, they will be used to define the general science requirements of the GGSF. Also included in the second volume is a physics feasibility study and abstracts of example Gas-Grain Simulation Facility experiments and related experiments in progress.

Astrophysics related programs at center for underground physics (CUP)

NASA Astrophysics Data System (ADS)

Kim, Yeongduk

2018-04-01

We are developing experimental programs related to particle astrophysics at the Center for Underground Physics (CUP); searching for neutrino-less double beta decay (0νββ) of 100Mo nuclei and sterile neutrinos in the mass range of eV using reactor neutrinos. Expected sensitivities of AMoRE double beta decay experiment and the results from recent NEOS experiment are described. Utilizing the facilities for ultra-low radioactivity measurement at the center, we are planning to measure the decay of 180mTa which is important to the nucleosynthesis of heavy nuclei.

Research in space physics at the University of Iowa

NASA Technical Reports Server (NTRS)

Vanallen, J. A.

1979-01-01

Current investigations relating to energetic particles and the electric, magnetic, and electromagnetic fields associated with the earth, the sun, the moon, the planets, comets, and the interplanetary medium are reported. Primary emphasis is on observational work using a wide diversity of intruments on satellites of the earth and the moon and on planetary and interplanetary spacecraft, and on phenomenological analysis and interpretation. Secondary emphasis is given to closely related observational work by ground based radio-astronomical and optical techniques, and to theoretical problems in plasma physics as relevant to solar, planetary, and interplanetary phenomena.

From black holes to quantum gravity

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

Sanchez, N.

1987-01-01

Since modern physics now deals simultaneously with quantum theory, general relativity, cosmology and elementary particle physics, this volume caters to the need for a book of such a wide scope of interest. Aspects of grand unification, the thermodynamics of space-time, the loss of quantum coherence and the problem of time are expertly treated within a unified presentation. Contents: Introduction; The Global Structure of Space-time in the Classical Theory of General Relativity; Connection between the Structure of the Space-time and the Propagation of Quantum Fields; The Different Approaches to Quantization; Outlook and Conclusions.

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.

Particle rings and astrophysical accretion discs

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

Lovelace, R. V. E., E-mail: RVL1@cornell.edu; Romanova, M. M., E-mail: romanova@astro.cornell.edu

Norman Rostoker had a wide range of interests and significant impact on the plasma physics research at Cornell during the time he was a Cornell professor. His interests ranged from the theory of energetic electron and ion beams and strong particle rings to the related topics of astrophysical accretion discs. We outline some of the topics related to rings and discs including the Rossby wave instability which leads to formation of anticyclonic vortices in astrophysical discs. These vorticies are regions of high pressure and act to trap dust particles which in turn may facilitate planetesimals growth in proto-planetary disks andmore » could be important for planet formation. Analytical methods and global 3D magneto-hydrodynamic simulations have led to rapid advances in our understanding of discs in recent years.« less

Hugoniot and refractive indices of bromoform under shock compression

NASA Astrophysics Data System (ADS)

Liu, Q. C.; Zeng, X. L.; Zhou, X. M.; Luo, S. N.

2018-01-01

We investigate physical properties of bromoform (liquid CHBr3) including compressibility and refractive index under dynamic extreme conditions of shock compression. Planar shock experiments are conducted along with high-speed laser interferometry. Our experiments and previous results establish a linear shock velocity-particle velocity relation for particle velocities below 1.77 km/s, as well as the Hugoniot and isentropic compression curves up to ˜21 GPa. Shock-state refractive indices of CHBr3 up to 2.3 GPa or ˜26% compression, as a function of density, can be described with a linear relation and follows the Gladstone-Dale relation. The velocity corrections for laser interferometry measurements at 1550 nm are also obtained.

High Energy Density Physics and Exotic Acceleration Schemes

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

Cowan, T.; /General Atomics, San Diego; Colby, E.

2005-09-27

The High Energy Density and Exotic Acceleration working group took as our goal to reach beyond the community of plasma accelerator research with its applications to high energy physics, to promote exchange with other disciplines which are challenged by related and demanding beam physics issues. The scope of the group was to cover particle acceleration and beam transport that, unlike other groups at AAC, are not mediated by plasmas or by electromagnetic structures. At this Workshop, we saw an impressive advancement from years past in the area of Vacuum Acceleration, for example with the LEAP experiment at Stanford. And wemore » saw an influx of exciting new beam physics topics involving particle propagation inside of solid-density plasmas or at extremely high charge density, particularly in the areas of laser acceleration of ions, and extreme beams for fusion energy research, including Heavy-ion Inertial Fusion beam physics. One example of the importance and extreme nature of beam physics in HED research is the requirement in the Fast Ignitor scheme of inertial fusion to heat a compressed DT fusion pellet to keV temperatures by injection of laser-driven electron or ion beams of giga-Amp current. Even in modest experiments presently being performed on the laser-acceleration of ions from solids, mega-amp currents of MeV electrons must be transported through solid foils, requiring almost complete return current neutralization, and giving rise to a wide variety of beam-plasma instabilities. As keynote talks our group promoted Ion Acceleration (plenary talk by A. MacKinnon), which historically has grown out of inertial fusion research, and HIF Accelerator Research (invited talk by A. Friedman), which will require impressive advancements in space-charge-limited ion beam physics and in understanding the generation and transport of neutralized ion beams. A unifying aspect of High Energy Density applications was the physics of particle beams inside of solids, which is proving to be a very important field for diverse applications such as muon cooling, fusion energy research, and ultra-bright particle and radiation generation with high intensity lasers. We had several talks on these and other subjects, and many joint sessions with the Computational group, the EM Structures group, and the Beam Generation group. We summarize our groups' work in the following categories: vacuum acceleration schemes; ion acceleration; particle transport in solids; and applications to high energy density phenomena.« less

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.

LHC@Home: a BOINC-based volunteer computing infrastructure for physics studies at CERN

NASA Astrophysics Data System (ADS)

Barranco, Javier; Cai, Yunhai; Cameron, David; Crouch, Matthew; Maria, Riccardo De; Field, Laurence; Giovannozzi, Massimo; Hermes, Pascal; Høimyr, Nils; Kaltchev, Dobrin; Karastathis, Nikos; Luzzi, Cinzia; Maclean, Ewen; McIntosh, Eric; Mereghetti, Alessio; Molson, James; Nosochkov, Yuri; Pieloni, Tatiana; Reid, Ivan D.; Rivkin, Lenny; Segal, Ben; Sjobak, Kyrre; Skands, Peter; Tambasco, Claudia; Veken, Frederik Van der; Zacharov, Igor

2017-12-01

The LHC@Home BOINC project has provided computing capacity for numerical simulations to researchers at CERN since 2004, and has since 2011 been expanded with a wider range of applications. The traditional CERN accelerator physics simulation code SixTrack enjoys continuing volunteers support, and thanks to virtualisation a number of applications from the LHC experiment collaborations and particle theory groups have joined the consolidated LHC@Home BOINC project. This paper addresses the challenges related to traditional and virtualized applications in the BOINC environment, and how volunteer computing has been integrated into the overall computing strategy of the laboratory through the consolidated LHC@Home service. Thanks to the computing power provided by volunteers joining LHC@Home, numerous accelerator beam physics studies have been carried out, yielding an improved understanding of charged particle dynamics in the CERN Large Hadron Collider (LHC) and its future upgrades. The main results are highlighted in this paper.

Nuclear and particle physics in the early universe

NASA Technical Reports Server (NTRS)

Schramm, D. N.

1981-01-01

Basic principles and implications of Big Bang cosmology are reviewed, noting the physical evidence of a previous universe temperature of 10,000 K and theoretical arguments such as grand unification decoupling indicating a primal temperature of 10 to the 15th eV. The Planck time of 10 to the -43rd sec after the Big Bang is set as the limit before which gravity was quantized and nothing is known. Gauge theories of elementary particle physics are reviewed for successful predictions of similarity in weak and electromagnetic interactions and quantum chromodynamic predictions for strong interactions. The large number of photons in the universe relative to the baryons is considered and the grand unified theories are cited as showing the existence of baryon nonconservation as an explanation. Further attention is given to quark-hadron phase transition, the decoupling for the weak interaction and relic neutrinos, and Big Bang nucleosynthesis.

Numerical study into the morphology and formation mechanisms of three-dimensional particle structures in vibrated cylindrical cavities with various heating conditions

NASA Astrophysics Data System (ADS)

Lappa, Marcello

2016-10-01

The present analysis extends the author's earlier work [Lappa, Phys. Fluids 26, 093301 (2014), 10.1063/1.4893078] on the properties of patterns formed by the spontaneous accumulation and ordering of solid particles in certain types of flow. It is shown that under certain conditions, when subjected to vibrations to induce natural flow, nonisothermal fluids with dispersed solid particles are characterized by intervals of solid-pattern-forming behavior due to particle rearrangements preceded by intervals in which no recognizable structures of solid matter can be detected. The dynamics of these systems are highly nonlinear in nature. Because this family of particle attractors is known to exhibit strong sensitivity to the symmetry properties of the considered vibrated system and related geometrical constraints, the present study attempts to clarify the related dynamics in a geometry with curved walls (cylindrical enclosure). In particular, by assuming vibrations always directed perpendicularly to the imposed temperature gradient, we show that the morphology, spatial extension (percentage of physical volume occupied), separation (spatial distance), and mechanisms responsible for the formation of the resulting particle structures change significantly according to whether the temperature gradient is parallel or perpendicular to the symmetry axis of the cylinder. This indicates that the physics is not invariant with respect to 90° rotations in space of the specific forcing considered (direction of the imposed temperature gradient and associated perpendicular vibrations). Additional insights into the problem are obtained by assessing separately the influence played by the time-averaged (mean) and oscillatory effects. According to the numerical results, the intriguing diversity of particle agglomerates results from the different role or importance played by (curved or straight) boundaries in constraining particles and from the different structure and topology of the resulting macroscopic (large-scale) thermovibrational flow oscillating in time at the same frequency of the imposed vibrations.

[Dynamics of soil physical properties and biological soil crust during the vegetation restoration process of abandoned croplands in the Ordos Plateau, China].

PubMed

Cai, Wen Tao; Li, He Yi; Lai, Li Ming; Zhang, Xiao Long; Guan, Tian Yu; Zhou, Ji Hua; Jiang, Lian He; Zheng, Yuan Run

2017-03-18

A series of typical abandoned croplands in the regions of Ruanliang and Yingliang in the Ordos Plateau, China, were selected, and dynamics of the surface litter, biological soil crust and soil bulk density, soil texture, and soil moisture in different soil layers were investigated. The results showed that in the abandoned cropland in Ruanliang, the clay particle content and surface litter of the surface soil layer (0-10 cm) increased during the restoration process, while that of soil bulk density substantially decreased and soil water content slightly increased in the surface soil. In the medium soil layer (10-30 cm), the clay particle content increased and the soil water content slightly decreased. In the deep soil layer (30-50 cm), there was a relatively large variation in the physical properties. In the abandoned cropland in Yingliang, the coverage of litter and the coverage and thickness of the biological soil crust increased during the abandonment process. The surface soil bulk density, soil clay particle content and soil water content remained constant in 0-10 cm soil layer, while the physical properties varied substantially in 10-40 cm soil layer. The shallow distribution of the soil water content caused by the accumulation of the litter and clay particles on the soil surface might be the key reason of the replacement of the semi-shrub Artemisia ordosica community with a perennial grass community over the last 20 years of the abandoned cropland in Ruanliang. The relatively high soil water content in the shallow layer and the development of the biological soil crust might explain why the abandoned cropland in Yingliang was not invaded by the semi-shrub A. ordosica during the restoration process.

Development of compact particle detectors for space based instruments

NASA Astrophysics Data System (ADS)

Barner, Lindsey; Grove, Andrew; Mohler, Jacob; Sisson, Caleb; Roth, Alex; Kryemadhi, Abaz

2017-01-01

The Silicon Photomultipliers (SiPMs) are new photon-detectors which have been increasingly used in particle physics. Their small size, good single photon resolution, simple readout, and immunity to magnetic fields offers benefits compared to traditional photomultipliers. LYSO and CeBr3 crystals are relatively new scintillators with high stopping power, very good light yield and fast decay time. The response of these detectors to low energy gamma rays will be presented. NASA Pennsylvania Space Grant Consortium.

Degradation Signatures of Open Ocean Microplastic Debris

NASA Astrophysics Data System (ADS)

Lavender Law, K. L.; Donohue, J. L.; Collins, T.; Proskurowsi, G.; Andrady, A. L.

2016-02-01

Microplastics collected from the open ocean offer few clues about their origin and history. There is currently no method to determine how long ocean plastic has undergone environmental weathering, how quickly fragmentation has occurred, or how small microplastic particles will ultimately become before (or if) they are fully degraded by microbial action. In the current absence of results from laboratory and field experiments designed to address these questions, we meticulously examined physical and chemical characteristics of open ocean microplastic particles collected over a 16-year period for clues about their weathering history. More than 1000 microplastic particles collected in the western North Atlantic between 1991 and 2007 were analyzed to determine polymer type, material density, mass and particle size, and were used to create a detailed catalogue of common microscopic surface features likely related to environmental exposure and weathering. Polyethylene and polypropylene, the two buoyant resins most commonly collected at the sea surface, can typically be distinguished by visual microscopy alone, and their particular characteristics lead us to hypothesize that these two resins weaken and fragment in different ways and on different time scales. A subset of resin pellets collected at sea were also analyzed using FTIR-ATR and/or FTIR microscopy for signatures of chemical degradation (e.g., carbonyl index) that are related to physical weathering characteristics such as color, quantified by the yellowness index.

[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.

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

A summary report on the search for current technologies and developers to develop depth profiling/physical parameter end effectors

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

Nguyen, Q.H.

1994-09-12

This report documents the search strategies and results for available technologies and developers to develop tank waste depth profiling/physical parameter sensors. Sources searched include worldwide research reports, technical papers, journals, private industries, and work at Westinghouse Hanford Company (WHC) at Richland site. Tank waste physical parameters of interest are: abrasiveness, compressive strength, corrosiveness, density, pH, particle size/shape, porosity, radiation, settling velocity, shear strength, shear wave velocity, tensile strength, temperature, viscosity, and viscoelasticity. A list of related articles or sources for each physical parameters is provided.

Space Applications of the FLUKA Monte-Carlo Code: Lunar and Planetary Exploration

NASA Technical Reports Server (NTRS)

Anderson, V.; Ballarini, F.; Battistoni, G.; Campanella, M.; Carboni, M.; Cerutti, F.; Elkhayari, N.; Empl, A.; Fasso, A.; Ferrari, A.;

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.

RELATING WEIGHT AND COUNT DISTRIBUTIONS OF STREAM BED GRAVEL

EPA Science Inventory

The size distribution of particles in a stream bed reflects the stream hydrology as well as its physical and chemical water quality characteristics. In environmental assessments, gravel distribution determines habitat quality for aquatic insects and stream suitability for spawnin...

Texas Symposium on Relativistic Astrophysics, 11th, Austin, TX, December 12-17, 1982, Proceedings

NASA Technical Reports Server (NTRS)

Evans, D. S. (Editor)

1984-01-01

Various papers on relativistic astrophysics are presented. The general subjects addressed include: particle physics and astrophysics, general relativity, large-scale structure, big bang cosmology, new-generation telescopes, pulsars, supernovae, high-energy astrophysics, and active galaxies.

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.

Fundamentals of Plasma Physics

NASA Astrophysics Data System (ADS)

Bellan, Paul M.

2008-07-01

Preface; 1. Basic concepts; 2. The Vlasov, two-fluid, and MHD models of plasma dynamics; 3. Motion of a single plasma particle; 4. Elementary plasma waves; 5. Streaming instabilities and the Landau problem; 6. Cold plasma waves in a magnetized plasma; 7. Waves in inhomogeneous plasmas and wave energy relations; 8. Vlasov theory of warm electrostatic waves in a magnetized plasma; 9. MHD equilibria; 10. Stability of static MHD equilibria; 11. Magnetic helicity interpreted and Woltjer-Taylor relaxation; 12. Magnetic reconnection; 13. Fokker-Planck theory of collisions; 14. Wave-particle nonlinearities; 15. Wave-wave nonlinearities; 16. Non-neutral plasmas; 17. Dusty plasmas; Appendix A. Intuitive method for vector calculus identities; Appendix B. Vector calculus in orthogonal curvilinear coordinates; Appendix C. Frequently used physical constants and formulae; Bibliography; References; Index.

1999 LDRD Laboratory Directed Research and Development

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

Rita Spencer; Kyle Wheeler

This is the FY 1999 Progress Report for the Laboratory Directed Research and Development (LDRD) Program at Los Alamos National Laboratory. It gives an overview of the LDRD Program, summarizes work done on individual research projects, relates the projects to major Laboratory program sponsors, and provides an index to the principal investigators. Project summaries are grouped by their LDRD component: Competency Development, Program Development, and Individual Projects. Within each component, they are further grouped into nine technical categories: (1) materials science, (2) chemistry, (3) mathematics and computational science, (4) atomic, molecular, optical, and plasma physics, fluids, and particle beams, (5)more » engineering science, (6) instrumentation and diagnostics, (7) geoscience, space science, and astrophysics, (8) nuclear and particle physics, and (9) bioscience.« less

Laboratory Directed Research and Development FY 1998 Progress Report

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

John Vigil; Kyle Wheeler

This is the FY 1998 Progress Report for the Laboratory Directed Research and Development (LDRD) Program at Los Alamos National Laboratory. It gives an overview of the LDRD Program, summarizes work done on individual research projects, relates the projects to major Laboratory program sponsors, and provides an index to the principle investigators. Project summaries are grouped by their LDRD component: Competency Development, Program Development, and Individual Projects. Within each component, they are further grouped into nine technical categories: (1) materials science, (2) chemistry, (3) mathematics and computational science, (4) atomic, molecular, optical, and plasma physics, fluids, and particle beams, (5)more » engineering science, (6) instrumentation and diagnostics, (7) geoscience, space science, and astrophysics, (8) nuclear and particle physics, and (9) bioscience.« less

Laboratory directed research and development: FY 1997 progress report

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

Vigil, J.; Prono, J.

1998-05-01

This is the FY 1997 Progress Report for the Laboratory Directed Research and Development (LDRD) program at Los Alamos National Laboratory. It gives an overview of the LDRD program, summarizes work done on individual research projects, relates the projects to major Laboratory program sponsors, and provides an index to the principal investigators. Project summaries are grouped by their LDRD component: Competency Development, Program Development, and Individual Projects. Within each component, they are further grouped into nine technical categories: (1) materials science, (2) chemistry, (3) mathematics and computational science, (4) atomic and molecular physics and plasmas, fluids, and particle beams, (5)more » engineering science, (6) instrumentation and diagnostics, (7) geoscience, space science, and astrophysics, (8) nuclear and particle physics, and (9) bioscience.« less

DOES A SCALING LAW EXIST BETWEEN SOLAR ENERGETIC PARTICLE EVENTS AND SOLAR FLARES?

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

Kahler, S. W., E-mail: AFRL.RVB.PA@kirtland.af.mil

2013-05-20

Among many other natural processes, the size distributions of solar X-ray flares and solar energetic particle (SEP) events are scale-invariant power laws. The measured distributions of SEP events prove to be distinctly flatter, i.e., have smaller power-law slopes, than those of the flares. This has led to speculation that the two distributions are related through a scaling law, first suggested by Hudson, which implies a direct nonlinear physical connection between the processes producing the flares and those producing the SEP events. We present four arguments against this interpretation. First, a true scaling must relate SEP events to all flare X-raymore » events, and not to a small subset of the X-ray event population. We also show that the assumed scaling law is not mathematically valid and that although the flare X-ray and SEP event data are correlated, they are highly scattered and not necessarily related through an assumed scaling of the two phenomena. An interpretation of SEP events within the context of a recent model of fractal-diffusive self-organized criticality by Aschwanden provides a physical basis for why the SEP distributions should be flatter than those of solar flares. These arguments provide evidence against a close physical connection of flares with SEP production.« less

A numerical study of bidisperse particles in cluster-induced turbulence

NASA Astrophysics Data System (ADS)

Patel, Ravi; Kong, Bo; Capecelatro, Jesse; Fox, Rodney; Desjardins, Olivier

2016-11-01

Particle-laden turbulent flow is an important feature of many diverse environmental and industrial systems. To elucidate the mechanics of these types of flows, we study cluster-induced turbulence (CIT), wherein momentum coupling between a carrier fluid and setting particles leads to turbulent-like fluctuations in various quantities of interest. In this work, simulations of CIT with bidisperse particles are presented. The flow of kinetic energy is tracked from its generation due to drag until its dissipation due to fluid viscosity and particle collisions. As suggested by Fox (2014), the particle kinetic energy is separated into a correlated turbulent kinetic energy and an uncorrelated granular energy. An overall energy balance is computed for various exchange terms to determine their relative importance and to understand the underlying physical mechanisms in bidisperse CIT. Additionally, volume fraction and velocity statistics for both particle types and the fluid are presented. From these results, the consequences on closures for Reynolds-averaged stress models of particle-laden flows are discussed. National Science Foundation.

Primordial Particles; Collisions of Inelastic Particles

NASA Astrophysics Data System (ADS)

Sagi, George

2011-03-01

Three-dimensional matter is not defined by Euclidian or Cartesian geometries. Newton's and Einstein's laws are related to the motions of elastic masses. The study of collisions of inelastic particles opens up new vistas in physics. The present article reveals how such particles create clusters composed of various numbers of particles. The Probability of each formation, duplets, triplets, etc. can be calculated. The particles are held together by a binding force, and depending upon the angles of collisions they may also rotate around their center of geometry. Because of these unique properties such inelastic particles are referred to as primordial particles, Pp. When a given density of Pp per cubic space is given, then random collisions create a field. The calculation of the properties of such primordial field is very complex and beyond the present study. However, the angles of collisions are infinite in principle, but the probabilities of various cluster sizes are quantum dependent. Consequently, field calculations will require new complex mathematical methods to be discovered yet.

Role of particle size and composition in metal adsorption by solids deposited on urban road surfaces.

PubMed

Gunawardana, Chandima; Egodawatta, Prasanna; Goonetilleke, Ashantha

2014-01-01

Despite common knowledge that the metal content adsorbed by fine particles is relatively higher compared to coarser particles, the reasons for this phenomenon have gained little research attention. The research study discussed in the paper investigated the variations in metal content for different particle sizes of solids associated with pollutant build-up on urban road surfaces. Data analysis confirmed that parameters favourable for metal adsorption to solids such as specific surface area, organic carbon content, effective cation exchange capacity and clay forming minerals content decrease with the increase in particle size. Furthermore, the mineralogical composition of solids was found to be the governing factor influencing the specific surface area and effective cation exchange capacity. There is high quartz content in particles >150 μm compared to particles <150 μm. As particle size reduces below 150 μm, the clay forming minerals content increases, providing favourable physical and chemical properties that influence adsorption. Copyright © 2013 Elsevier Ltd. All rights reserved.

Inertial focusing of spherical particles in rectangular microchannels over a wide range of Reynolds numbers.

PubMed

Liu, Chao; Hu, Guoqing; Jiang, Xingyu; Sun, Jiashu

2015-02-21

Inertial microfluidics has emerged as an important tool for manipulating particles and cells. For a better design of inertial microfluidic devices, we conduct 3D direct numerical simulations (DNS) and experiments to determine the complicated dependence of focusing behaviour on the particle size, channel aspect ratio, and channel Reynolds number. We find that the well-known focusing of the particles at the two centers of the long channel walls occurs at a relatively low Reynolds number, whereas additional stable equilibrium positions emerge close to the short walls with increasing Reynolds number. Based on the numerically calculated trajectories of particles, we propose a two-stage particle migration which is consistent with experimental observations. We further present a general criterion to secure good focusing of particles for high flow rates. This work thus provides physical insight into the multiplex focusing of particles in rectangular microchannels with different geometries and Reynolds numbers, and paves the way for efficiently designing inertial microfluidic devices.

Experimental Determination of Infrared Extinction Coefficients of Interplanetary Dust Particles

NASA Technical Reports Server (NTRS)

Spann, J. F., Jr.; Abbas, M. M.

1998-01-01

This technique is based on irradiating a single isolated charged dust particle suspended in balance by an electric field, and measuring the scattered radiation as a function of angle. The observed scattered intensity profile at a specific wavelength obtained for a dust particle of known composition is compared with Mie theory calculations, and the variable parameters relating to the particle size and complex refractive index are adjusted for a best fit between the two profiles. This leads to a simultaneous determination of the particle radius, the complex refractive index, and the scattering and extinction coefficients. The results of these experiments can be utilized to examine the IRAS and DIRBE (Diffuse Infrared Background Experiment) infrared data sets in order to determine the dust particle physical characteristics and distributions by using infrared models and inversion techniques. This technique may also be employed for investigation of the rotational bursting phenomena whereby large size cosmic and interplanetary particles are believed to fragment into smaller dust particles.

Gamma Rays at Very High Energies

NASA Astrophysics Data System (ADS)

Aharonian, Felix

This chapter presents the elaborated lecture notes on Gamma Rays at Very High Energies given by Felix Aharonian at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". Any coherent description and interpretation of phenomena related to gammarays requires deep knowledge of many disciplines of physics like nuclear and particle physics, quantum and classical electrodynamics, special and general relativity, plasma physics, magnetohydrodynamics, etc. After giving an introduction to gamma-ray astronomy the author discusses the astrophysical potential of ground-based detectors, radiation mechanisms, supernova remnants and origin of the galactic cosmic rays, TeV emission of young supernova remnants, gamma-emission from the Galactic center, pulsars, pulsar winds, pulsar wind nebulae, and gamma-ray loud binaries.

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…

Formulation and shelf life stability of water-borne lecithin nanoparticles for potential application in dietary supplements field.

PubMed

Edris, Amr E

2012-09-01

ABSTRACT The objective of the present investigation is to formulate commercial soybean lecithin as nanoparticles in solvent-free aqueous system for potential supplementary applications. A mechanical method, which involved two major steps, was used for that purpose. First, lecithin submicron particles (~ 0.5 μm) have been prepared by gradual hydration of lecithin powder using mechanical agitation. Finally, the size of these particles was further reduced to < 100 nm by using high-pressure microfluidization. The physical stability (appearance, particle size distribution, ζ-potential) and the chemical stability (lipid oxidation) of the dispersions carrying lecithin nanoparticles were assessed every 15 days during the 3-month shelf life period at two different temperatures. Results showed that the final particle size of lecithin in the freshly prepared aqueous dispersion was 79.8 ± 1.0 nm and the amount of peroxide detected was 3.5 ± 0.2 meq/kg lipid. At the end of the storage period, dispersions stored at 4°C exhibited physical and chemical stability as evident from the translucent appearance, the small change in particle size (84.1 ± 1.3 nm), and the small amount of generated peroxides (4.1 ± 0.2 meq/kg lipid). On the other hand, dispersions stored at 25°C were physically stable up to 60 days. Over that period, samples became turbid and the particle size increased to 145.0 ± 1.7 nm with a bimodal distribution pattern. This behavior was due to phospholipids (PLs) degradation and hydrolysis under acidic conditions, which proceeds faster at a relatively high temperature (25°C) than at (4°C). The outcome of this investigation may help in developing water-based dispersions carrying lecithin nanoparticles for dietary supplement of PLs.

Physical interactions of charged particles for radiotherapy and space applications.

PubMed

Zeitlin, Cary

2012-11-01

In this paper, the basic physics by which energetic charged particles deposit energy in matter is reviewed. Energetic charged particles are used for radiotherapy and are encountered in spaceflight, where they pose a health risk to astronauts. They interact with matter through nuclear and electromagnetic forces. Deposition of energy occurs mostly along the trajectory of the incoming particle, but depending on the type of incident particle and its energy, there is some nonzero probability for energy deposition relatively far from the nominal trajectory, either due to long-ranged knock-on electrons (sometimes called delta rays) or from the products of nuclear fragmentation, including neutrons. In the therapy setting, dose localization is of paramount importance, and the deposition of energy outside nominal treatment volumes complicates planning and increases the risk of secondary cancers as well as noncancer effects in normal tissue. Statistical effects are also important and will be discussed. In contrast to radiation therapy patients, astronauts in space receive comparatively small whole-body radiation doses from energetic charged particles and associated secondary radiation. A unique aspect of space radiation exposures is the high-energy heavy-ion component of the dose. This is not present in terrestrial exposures except in carbon-ion radiotherapy. Designers of space missions must limit exposures to keep risk within acceptable limits. These limits are, at present, defined for low-Earth orbit, but not for deep-space missions outside the geomagnetosphere. Most of the uncertainty in risk assessment for such missions comes from the lack of understanding of the biological effectiveness of the heavy-ion component, with a smaller component due to uncertainties in transport physics and dosimetry. These same uncertainties are also critical in the therapy setting.

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

Planck's constant and the three waves (TWs) of Einstein's covariant ether

NASA Astrophysics Data System (ADS)

Kostro, L.

1985-11-01

The implications of a three-wave model for elementary particles, satisfying the principles of both quantum mechanics and General Relativity (GR), are discussed. In GR, the ether is the fundamental source of all activity, where particles (waves) arise at singularities. Inertia and gravity are field properties of the ether. In flat regions of the space-time geodesic, wave excitations correspond to the presence of particles. A momentum-carrying excitation which occurs in the ether is a superluminal radiation (phase- or B-waves) which transports neither energy nor mass. Superposition of the B-waves produces soliton-like excitations on the ether to form C-waves, i.e., particles. The particle-waves travel through space-time on D-waves, and experience reflection, refraction and interference only where B-waves have interacted with the ether. The original particles, photons-maximons, existed at the Big Bang and had physical properties which are describable in terms of Planck's quantities.

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

Physical and chemical properties of ice residuals during the 2013 and 2014 CLACE campaigns

NASA Astrophysics Data System (ADS)

Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Hammer, Emanuel; Gysel, Martin; Färber, Raphael; Fuchs, Claudia; Schnaiter, Martin; Baltensperger, Urs; Schmidt, Susan; Schneider, Johannes; Bigi, Alessandro; Toprak, Emre; Linke, Claudia; Klimach, Thomas

2014-05-01

The shortcomings in our understanding and, thus, representation of aerosol-cloud interactions are one of the major sources of uncertainty in climate model projections. Among the poorly understood processes is mixed-phase cloud formation via heterogeneous nucleation, and the subsequent spatial and temporal evolution of such clouds. Cloud glaciation augments precipitation formation, resulting in decreased cloud cover and lifetime, and affects cloud radiative properties. Meanwhile, the physical and chemical properties of atmospherically relevant ice nuclei (IN), the sub-population of aerosol particles which enable heterogeneous nucleation, are not well known. Extraction of ice residuals (IR) in mixed-phase clouds is a difficult task, requiring separation of the few small, freshly formed ice crystals (the IR within such crystals can be deemed representative of the original IN) not only from interstitial particles, but also from the numerous supercooled droplets which have aerodynamic diameters similar to those of the ice crystals. In order to address the difficulties with ice crystal sampling and IR extraction in mixed-phase clouds, the new Ice Selective Inlet (ISI) has been designed and deployed at the Jungfraujoch field site. Small ice crystals are selectively sampled via the inlet with simultaneous counting, sizing and imaging of hydrometeors contained in the cloud by a set of optical particle spectrometers, namely Welas optical particle counters (OPC) and a Particle Phase Discriminator (PPD). The heart of the ISI is a droplet evaporation unit with ice-covered inner walls, resulting in removal of droplets using the Wegener-Bergeron-Findeisen process, while transmitting a relatively high fraction of small ice crystals. The ISI was deployed in the winters of 2013 and 2014 at the high alpine Jungfraujoch site (3580 m.a.s.l) during the intensive CLACE field campaigns. The measurements focused on analysis of the physical and chemical characteristics of IR and the microphysical properties of mixed-phase clouds. A host of aerosol instrumentation was deployed downstream of the ISI, including a Grimm OPC and a scanning mobility particle sizer (SMPS) for number size distribution measurements, as well as a single particle mass spectrometer (ALABAMA; 2013 only), single particle soot photometers (SP2) and a Wideband Integrated Bioaerosol Sensor (WIBS-4) for analysis of the chemical composition, with particular focus on the content of black carbon (BC) and biological particles in IR. Corresponding instrumentation sampled through a total aerosol inlet. By comparing observations from the ISI with those from the total inlet the characteristics of ice residuals relative to the total aerosol could be established. First results from these analyses will be presented.

Operational and design aspects of accelerators for medical applications

NASA Astrophysics Data System (ADS)

Schippers, Jacobus Maarten; Seidel, Mike

2015-03-01

Originally, the typical particle accelerators as well as their associated beam transport equipment were designed for particle and nuclear physics research and applications in isotope production. In the past few decades, such accelerators and related equipment have also been applied for medical use. This can be in the original physics laboratory environment, but for the past 20 years also in hospital-based or purely clinical environments for particle therapy. The most important specific requirements of accelerators for radiation therapy with protons or ions will be discussed. The focus will be on accelerator design, operational, and formal aspects. We will discuss the special requirements to reach a high reliability for patient treatments as well as an accurate delivery of the dose at the correct position in the patient using modern techniques like pencil beam scanning. It will be shown that the technical requirements, safety aspects, and required reliability of the accelerated beam differ substantially from those in a nuclear physics laboratory. It will be shown that this difference has significant implications on the safety and interlock systems. The operation of such a medical facility should be possible by nonaccelerator specialists at different operating sites (treatment rooms). The organization and role of the control and interlock systems can be considered as being the most crucially important issue, and therefore a special, dedicated design is absolutely necessary in a facility providing particle therapy.

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

Design of Magnetic Charged Particle Lens Using Analytical Potential Formula

NASA Astrophysics Data System (ADS)

Al-Batat, A. H.; Yaseen, M. J.; Abbas, S. R.; Al-Amshani, M. S.; Hasan, H. S.

2018-05-01

In the current research was to benefit from the potential of the two cylindrical electric lenses to be used in the product a mathematical model from which, one can determine the magnetic field distribution of the charged particle objective lens. With aid of simulink in matlab environment, some simulink models have been building to determine the distribution of the target function and their related axial functions along the optical axis of the charged particle lens. The present study showed that the physical parameters (i.e., the maximum value, Bmax, and the half width W of the field distribution) and the objective properties of the charged particle lens have been affected by varying the main geometrical parameter of the lens named the bore radius R.

On small beams with large topological charge: II. Photons, electrons and gravitational waves

NASA Astrophysics Data System (ADS)

Krenn, Mario; Zeilinger, Anton

2018-06-01

Beams of light with a large topological charge significantly change their spatial structure when they are focused strongly. Physically, it can be explained by an emerging electromagnetic field component in the direction of propagation, which is neglected in the simplified scalar wave picture in optics. Here we ask: is this a specific photonic behavior, or can similar phenomena also be predicted for other species of particles? We show that the same modification of the spatial structure exists for relativistic electrons as well as for focused gravitational waves. However, this is for different physical reasons: for electrons, which are described by the Dirac equation, the spatial structure changes due to a spin–orbit coupling in the relativistic regime. In gravitational waves described with linearized general relativity, the curvature of space–time between the transverse and propagation direction leads to the modification of the spatial structure. Thus, this universal phenomenon exists for both massive and massless elementary particles with spin 1/2, 1 and 2. It would be very interesting whether other types of particles such as composite systems (neutrons or C60) or neutrinos show a similar behavior and how this phenomenon can be explained in a unified physical way.

Future HEP Accelerators: The US Perspective

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

Bhat, Pushpalatha; Shiltsev, Vladimir

2015-11-02

Accelerator technology has advanced tremendously since the introduction of accelerators in the 1930s, and particle accelerators have become indispensable instruments in high energy physics (HEP) research to probe Nature at smaller and smaller distances. At present, accelerator facilities can be classified into Energy Frontier colliders that enable direct discoveries and studies of high mass scale particles and Intensity Frontier accelerators for exploration of extremely rare processes, usually at relatively low energies. The near term strategies of the global energy frontier particle physics community are centered on fully exploiting the physics potential of the Large Hadron Collider (LHC) at CERN throughmore » its high-luminosity upgrade (HL-LHC), while the intensity frontier HEP research is focused on studies of neutrinos at the MW-scale beam power accelerator facilities, such as Fermilab Main Injector with the planned PIP-II SRF linac project. A number of next generation accelerator facilities have been proposed and are currently under consideration for the medium- and long-term future programs of accelerator-based HEP research. In this paper, we briefly review the post-LHC energy frontier options, both for lepton and hadron colliders in various regions of the world, as well as possible future intensity frontier accelerator facilities.« less

Particle Theory & Cosmology

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

Shafi, Qaisar; Barr, Steven; Gaisser, Thomas

1. Executive Summary (April 1, 2012 - March 31, 2015) Title: Particle Theory, Particle Astrophysics and Cosmology Qaisar Shafi University of Delaware (Principal Investigator) Stephen M. Barr, University of Delaware (Co-Principal Investigator) Thomas K. Gaisser, University of Delaware (Co-Principal Investigator) Todor Stanev, University of Delaware (Co-Principal Investigator) The proposed research was carried out at the Bartol Research included Professors Qaisar Shafi Stephen Barr, Thomas K. Gaisser, and Todor Stanev, two postdoctoral fellows (Ilia Gogoladze and Liucheng Wang), and several graduate students. Five students of Qaisar Shafi completed their PhD during the period August 2011 - August 2014. Measures of themore » group’s high caliber performance during the 2012-2015 funding cycle included pub- lications in excellent refereed journals, contributions to working groups as well as white papers, and conference activities, which together provide an exceptional record of both individual performance as well as overall strength. Another important indicator of success is the outstanding quality of the past and current cohort of graduate students. The PhD students under our supervision regularly win the top departmental and university awards, and their publications records show excellence both in terms of quality and quantity. The topics covered under this grant cover the frontline research areas in today’s High Energy Theory & Phenomenology. For Professors Shafi and Barr they include LHC related topics including supersymmetry, collider physics, fl vor physics, dark matter physics, Higgs boson and seesaw physics, grand unifi and neutrino physics. The LHC two years ago discovered the Standard Model Higgs boson, thereby at least partially unlocking the secrets behind electroweak symmetry breaking. We remain optimistic that new and exciting physics will be found at LHC 14, which explain our focus on physics beyond the Standard Model. Professors Shafi continued his investigations in cosmology, specifically on supergravity and GUT infl models, primordial gravity waves, dark matter models. The origin of baryon and dark matter in the universe has been explored by Professors Barr and Shafi The research program of Professors Gaisser and Stanev address current research topics in Particle Astrophysics, in particular atmospheric and cosmogenic neutrinos and ultra-high energy cosmic rays. Work also included use of LHC data to improve tools for interpreting cascades generated in the atmosphere by high-energy particles from the cosmos. Cosmogenic neutrinos produced by interactions of ultra-high energy cosmic rays as they propagate through the cosmic microwave background radiation provides insight into the origin of the highest energy particles in nature. Overall, the research covered topics in the energy, cosmic and intensity frontiers.« less

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).

On general features of warm dark matter with reduced relativistic gas

NASA Astrophysics Data System (ADS)

Hipólito-Ricaldi, W. S.; vom Marttens, R. F.; Fabris, J. C.; Shapiro, I. L.; Casarini, L.

2018-05-01

Reduced relativistic gas (RRG) is a useful approach to describe the warm dark matter (WDM) or the warmness of baryonic matter in the approximation when the interaction between the particles is irrelevant. The use of Maxwell distribution leads to the complicated equation of state of the Jüttner model of relativistic ideal gas. The RRG enables one to reproduce the same physical situation but in a much simpler form. For this reason RRG can be a useful tool for the theories with some sort of a "new Physics". On the other hand, even without the qualitatively new physical implementations, the RRG can be useful to describe the general features of WDM in a model-independent way. In this sense one can see, in particular, to which extent the cosmological manifestations of WDM may be dependent on its Particle Physics background. In the present work RRG is used as a complementary approach to derive the main observational features for the WDM in a model-independent way. The only assumption concerns a non-negligible velocity v for dark matter particles which is parameterized by the warmness parameter b. The relatively high values of b ( b^2˜ 10^{-6}) erase the radiation (photons and neutrinos) dominated epoch and cause an early warm matter domination after inflation. Furthermore, RRG approach enables one to quantify the lack of power in linear matter spectrum at small scales and in particular, reproduces the relative transfer function commonly used in context of WDM with accuracy of ≲ 1%. A warmness with b^2≲ 10^{-6} (equivalent to v≲ 300 km/s) does not alter significantly the CMB power spectrum and is in agreement with the background observational tests.

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.

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

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.

Einstein’s Clocks

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

Lincoln, Don

One of the most non-intuitive physics theories ever devised is Einstein’s Theory of Special Relativity, which claim such crazy-sounding things as two people disagreeing on such familiar concepts as length and time. In this video, Fermilab’s Dr. Don Lincoln shows that every single day particle physicists prove that moving clocks tick more slowly than stationary ones. He uses an easy to understand example of particles that move for far longer distances than you would expect from combining their velocity and stationary lifetime.

Physical Principles of Development of the State Standard of Biological Cell Polarizability

NASA Astrophysics Data System (ADS)

Shuvalov, G. V.; Generalov, K. V.; Generalov, V. M.; Kruchinina, M. V.; Koptev, E. S.; Minin, O. V.; Minin, I. V.

2018-03-01

A new state standard of biological cell polarizability based on micron-size latex particles has been developed. As a standard material, it is suggested to use polystyrene. Values of the polarizability calculated for erythrocytes and values of the polarizability of micron-size spherical latex particles measured with measuring-computing complexes agree within the limits of satisfactory relative error. The Standard allows one the unit of polarizability measurements [m3] to be assigned to cells and erythrocytes for the needs of medicine.

Photoacoustic Doppler effect from flowing small light-absorbing particles.

PubMed

Fang, Hui; Maslov, Konstantin; Wang, Lihong V

2007-11-02

From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

The Role of Substorms in Storm-time Particle Acceleration

NASA Astrophysics Data System (ADS)

Daglis, Ioannis A.; Kamide, Yohsuke

The terrestrial magnetosphere has the capability to rapidly accelerate charged particles up to very high energies over relatively short times and distances. Acceleration of charged particles is an essential ingredient of both magnetospheric substorms and space storms. In the case of space storms, the ultimate result is a bulk flow of electric charge through the inner magnetosphere, commonly known as the ring current. Syun-Ichi Akasofu and Sydney Chapman, two of the early pioneers in space physics, postulated that the bulk acceleration of particles during storms is rather the additive result of partial acceleration during consecutive substorms. This paradigm has been heavily disputed during recent years. The new case is that substorm acceleration may be sufficient to produce individual high-energy particles that create auroras and possibly harm spacecraft, but it cannot produce the massive acceleration that constitutes a storm. This paper is a critical review of the long-standing issue of the storm-substorm relationship, or—in other words—the capability or necessity of substorms in facilitating or driving the build-up of the storm-time ring current. We mainly address the physical effect itself, i.e. the bulk acceleration of particles, and not the diagnostic of the process, i.e. the Dst index, which is rather often the case. Within the framework of particle acceleration, substorms retain their storm-importance due to the potential of substorm-induced impulsive electric fields in obtaining the massive ion acceleration needed for the storm-time ring current buildup.

Self-consistent discharge growing model of helicon plasma

NASA Astrophysics Data System (ADS)

Isayama, Shogo; Hada, Tohru; Shinohara, Shunjiro; Tanikawa, Takao

2015-11-01

Helicon plasma is a high-density and low-temperature plasma generated by the electromagnetic (Helicon) wave excited in the plasma. It is thought to be useful for various applications including electric thrusters. Physics of helicon plasma production involves such fundamental processes as the wave propagation (dispersion relation), collisional and non-collisional wave damping, plasma heating, ionization/recombination of neutral particles, and modification of the dispersion relation by newly ionized plasma. There remain a number of unsolved physical issues such as, how the Helicon and the TG modes influence the plasma density, electron temperature and their spatial profiles. While the Helicon mode is absorbed in the bulk plasma, the TG mode is mostly absorbed near the edge of the plasma. The local power deposition in the helicon plasma is mostly balanced by collisional loss. This local power balance can give rise to the inhomogeneous electron temperature profile that leads to time evolution of density profile and dispersion relation. In our study, we construct a self-consistent model of the discharge evolution that includes the wave excitation, electron heat transfer, and diffusion of charged particles.

All-loop Mondrian diagrammatics and 4-particle amplituhedron

NASA Astrophysics Data System (ADS)

An, Yang; Li, Yi; Li, Zhinan; Rao, Junjie

2018-06-01

Based on 1712.09990 which handles the 4-particle amplituhedron at 3-loop, we have found an extremely simple pattern, yet far more non-trivial than one might naturally expect: the all-loop Mondrian diagrammatics. By further simplifying and rephrasing the key relation of positivity in the amplituhedron setting, remarkably, we find a completeness relation unifying all diagrams of the Mondrian types for the 4-particle integrand of planar N = 4 SYM to all loop orders, each of which can be mapped to a simple product following a few plain rules designed for this relation. The explicit examples we investigate span from 3-loop to 7-loop order, and based on them, we classify the basic patterns of Mondrian diagrams into four types: the ladder, cross, brick-wall and spiral patterns. Interestingly, for some special combinations of ordered subspaces (a concept defined in the previous work), we find failed exceptions of the completeness relation which are called "anomalies", nevertheless, they substantially give hints on the all-loop recursive proof of this relation. These investigations are closely related to the combinatoric knowledge of separable permutations and Schröder numbers, and go even further from a diagrammatic perspective. For physical relevance, we need to further consider dual conformal invariance for two basic diagrammatic patterns to correct the numerator for a local integrand involving one or both of such patterns, while the denominator encoding its pole structure and also the sign factor, are already fixed by rules of the completeness relation. With this extra treatment to ensure the integrals are dual conformally invariant, each Mondrian diagram can be exactly translated to its corresponding physical loop integrand after being summed over all ordered subspaces that admit it.

From the necessary to the possible: the genesis of the spin-statistics theorem

NASA Astrophysics Data System (ADS)

Blum, Alexander

2014-12-01

The spin-statistics theorem, which relates the intrinsic angular momentum of a single particle to the type of quantum statistics obeyed by a system of many such particles, is one of the central theorems in quantum field theory and the physics of elementary particles. It was first formulated in 1939/40 by Wolfgang Pauli and his assistant Markus Fierz. This paper discusses the developments that led up to this first formulation, starting from early attempts in the late 1920s to explain why charged matter particles obey Fermi-Dirac statistics, while photons obey Bose-Einstein statistics. It is demonstrated how several important developments paved the way from such general philosophical musings to a general (and provable) theorem, most notably the use of quantum field theory, the discovery of new elementary particles, and the generalization of the notion of spin. It is also discussed how the attempts to prove a spin-statistics connection were driven by Pauli from formal to more physical arguments, culminating in Pauli's 1940 proof. This proof was a major success for the beleaguered theory of quantum field theory and the methods Pauli employed proved essential for the renaissance of quantum field theory and the development of renormalization techniques in the late 1940s.

How an interacting many-body system tunnels through a potential barrier to open space

PubMed Central

Lode, Axel U.J.; Streltsov, Alexej I.; Sakmann, Kaspar; Alon, Ofir E.; Cederbaum, Lorenz S.

2012-01-01

The tunneling process in a many-body system is a phenomenon which lies at the very heart of quantum mechanics. It appears in nature in the form of α-decay, fusion and fission in nuclear physics, and photoassociation and photodissociation in biology and chemistry. A detailed theoretical description of the decay process in these systems is a very cumbersome problem, either because of very complicated or even unknown interparticle interactions or due to a large number of constituent particles. In this work, we theoretically study the phenomenon of quantum many-body tunneling in a transparent and controllable physical system, an ultracold atomic gas. We analyze a full, numerically exact many-body solution of the Schrödinger equation of a one-dimensional system with repulsive interactions tunneling to open space. We show how the emitted particles dissociate or fragment from the trapped and coherent source of bosons: The overall many-particle decay process is a quantum interference of single-particle tunneling processes emerging from sources with different particle numbers taking place simultaneously. The close relation to atom lasers and ionization processes allows us to unveil the great relevance of many-body correlations between the emitted and trapped fractions of the wave function in the respective processes. PMID:22869703

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

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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…

Inerton fields: very new ideas on fundamental physics

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

Krasnoholovets, Volodymyr

2010-12-22

Modern theories of everything, or theories of the grand unification of all physical interactions, try to describe the whole world starting from the first principles of quantum theory. However, the first principles operate with undetermined notions, such as the wave {psi}-function, particle, lepton and quark, de Broglie and Compton wavelengths, mass, electric charge, spin, electromagnetic field, photon, gravitation, physical vacuum, space, etc. From a logical point of view this means that such modern approach to the theory of everything is condemned to failure... Thus, what should we suggest to improve the situation? It seems quite reasonable to develop initially amore » theory of something, which will be able to clarify the major fundamental notions (listed above) that physics operates with every day. What would be a starting point in such approach? Of course a theory of space as such, because particles and all physical fields emerge just from space. After that, when a particle and fields (and hence the fields' carriers) are well defined and introduced in the well defined physical space, different kinds of interactions can be proposed and investigated. Moreover, we must also allow for a possible interaction of a created particle with the space that generated the appearance of the particle. The mathematical studies of Michel Bounias and the author have shown what the real physical space is, how the space is constituted, how it is arranged and what its elements are. Having constructed the real physical space we can then derive whatever we wish, in particular, such basic notions as mass, particle and charge. How are mechanics of such objects (a massive particle, a charged massive particle) organised? The appropriate theory of motion has been called a sub microscopic mechanics of particles, which is developed in the real physical space, not an abstract phase space, as conventional quantum mechanics does. A series of questions arise: can these two mechanics (submicroscopic and conventional quantum mechanics) be unified?, what can such unification bring new for us?, can such submicroscopic mechanics be a starting point for the derivation of the phenomenon of gravity?, can this new theory be a unified physical theory?, does the theory allow experimental verification? These major points have been clarified in detail. And, perhaps, the most intriguing aspect of the theory is the derivation of a new physical field associated with the notion of mass (or rather inertia of a particle, which has been called the inerton field and which represents a real sense of the particle's wave {psi}-function). This field emerges by analogy with the electromagnetic field associated with the notion of the electric charge. Yes, the postulated inerton field has being tested in a series of different experiments. Even more, the inerton field might have a number of practical applications...« less

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.

Heat transfer from nanoparticles: A corresponding state analysis

PubMed Central

Merabia, Samy; Shenogin, Sergei; Joly, Laurent; Keblinski, Pawel; Barrat, Jean-Louis

2009-01-01

In this contribution, we study situations in which nanoparticles in a fluid are strongly heated, generating high heat fluxes. This situation is relevant to experiments in which a fluid is locally heated by using selective absorption of radiation by solid particles. We first study this situation for different types of molecular interactions, using models for gold particles suspended in octane and in water. As already reported in experiments, very high heat fluxes and temperature elevations (leading eventually to particle destruction) can be observed in such situations. We show that a very simple modeling based on Lennard–Jones (LJ) interactions captures the essential features of such experiments and that the results for various liquids can be mapped onto the LJ case, provided a physically justified (corresponding state) choice of parameters is made. Physically, the possibility of sustaining very high heat fluxes is related to the strong curvature of the interface that inhibits the formation of an insulating vapor film. PMID:19571000

Iterants, Fermions and Majorana Operators

NASA Astrophysics Data System (ADS)

Kauffman, Louis H.

Beginning with an elementary, oscillatory discrete dynamical system associated with the square root of minus one, we study both the foundations of mathematics and physics. Position and momentum do not commute in our discrete physics. Their commutator is related to the diffusion constant for a Brownian process and to the Heisenberg commutator in quantum mechanics. We take John Wheeler's idea of It from Bit as an essential clue and we rework the structure of that bit to a logical particle that is its own anti-particle, a logical Marjorana particle. This is our key example of the amphibian nature of mathematics and the external world. We show how the dynamical system for the square root of minus one is essentially the dynamics of a distinction whose self-reference leads to both the fusion algebra and the operator algebra for the Majorana Fermion. In the course of this, we develop an iterant algebra that supports all of matrix algebra and we end the essay with a discussion of the Dirac equation based on these principles.

Final Technical Report for Award SC0008613

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

Knopf, Daniel A.

Discovering how aerosol particles, present in the atmosphere in sizes of a few nanometers to hundred micrometers, initiate ice crystal formation represents a great challenge. Atmospheric ice nucleation is important because ice crystals alter the radiative properties of clouds and thus climate, and impact precipitation and thus the hydrological cycle. The difficulty in predicting atmospheric ice formation is attributable at least in part, to the diversity of ice nucleation pathways, the physical and chemical complexity of the ice nucleating particles (INPs), and the relatively small numbers of INPs (compared with all other aerosol particles), sometimes less than one in 100000.more » These factors in turn makes constraining ice nucleation parameterizations for modeling applications challenging. The majority of airborne particles are known to be organic in nature or contain organic biogenic material. The presence of organic material adds to the complexity of the particles and therefore the predictability of ice nucleation events since the organic species can display different phase states, e.g. liquid or solid, in response to temperature and humidity. The award DE-SC0008613 to PI Prof. Daniel Knopf at Stony Brook University, “Relating the Chemical and Physical Properties of Aerosols to the Water Uptake and Ice Nucleation Potential of Particles Collected During the Carbonaceous Aerosols and Radiative Effects Study (CARES)”, allowed examination of laboratory generated aerosol particles and field-collected particles for their propensity to nucleate ice under typical tropospheric conditions and relate ice nucleation to the physicochemical properties of the particles including their morphology and chemical composition. This in turn allowed for development of ice nucleation parameterizations for implementation in cloud models. The award resulted in 10 peer-reviewed publications and more than 20 seminar and conference presentations. We demonstrated that the rate of immersion freezing, when a particle immersed in an aqueous droplet acts as an ice nucleus (IN), can be predicted by knowledge of the IN particle type present and the droplet’s water activity which is equal to ambient relative humidity. Our water activity based immersion freezing model is successful in predicting freezing data including INPs such as mineral dusts, marine biological material, organic species, and surfactant molecules. Its mathematical simplicity makes it an ideal candidate for implementation in cloud and climate models. Furthermore, we could show that this model can reproduce many past laboratory measurements which were generated using a variety of instruments to study immersion freezing. Lastly, we have demonstrated that this model can also be applied to field collected particles. Currently, this novel physical parameterization of immersion freezing is being implemented in a cloud model. We examined the physicochemical properties and the ice nucleation potential of particles collected during CARES applying a novel experimental method that allows identification of the individual INPs within a large population of particles sampled from an ambient environment. Taking advantage of a variety of micro-spectroscopic techniques, we characterized the composition and morphology of IN and non-IN particles present in the airborne population. We developed a new parameterization for quantifying the mixing state of the entire aerosol populations by introducing a mixing state index. We found that the identified INPs belong to the most common particle-type classes observed in the CARES field samples and as such are not special or rare particles. In other words, the INPs can be shown not to be unique in contrast to the common paradigm of being rare and exceptional. Either there are differences between particles acting as IN and particles not acting as IN which are beyond our current detection limit or nucleation occurs randomly on the surface of any one of these compositionally equivalent particles. These results suggest that total particle surface area of the different particle types present in the aerosol population is also a crucial factor when predicting ice nucleation in an air mass. We also observed that ambient organic aerosol particles can initiate ice nucleation and corroborated these findings using laboratory generated organic particles. These experiments demonstrated that information of the organic phase state is important for predicting the ice nucleation pathway and the ability of an organic particle to participate in atmospheric ice crystal formation. This award resulted in substantial new insights in the processes governing immersion freezing, the role of organic aerosol particles in ice cloud formation, and the importance of the ambient aerosol population for prediction of ice nucleation in an air parcel. These findings have significant implications for modeling and field measurement strategies of atmospheric ice nucleation.« less

Mass spectrometric analysis and aerodynamic properties of various types of combustion-related aerosol particles

NASA Astrophysics Data System (ADS)

Schneider, J.; Weimer, S.; Drewnick, F.; Borrmann, S.; Helas, G.; Gwaze, P.; Schmid, O.; Andreae, M. O.; Kirchner, U.

2006-12-01

Various types of combustion-related particles in the size range between 100 and 850 nm were analyzed with an aerosol mass spectrometer and a differential mobility analyzer. The measurements were performed with particles originating from biomass burning, diesel engine exhaust, laboratory combustion of diesel fuel and gasoline, as well as from spark soot generation. Physical and morphological parameters like fractal dimension, effective density, bulk density and dynamic shape factor were derived or at least approximated from the measurements of electrical mobility diameter and vacuum aerodynamic diameter. The relative intensities of the mass peaks in the mass spectra obtained from particles generated by a commercial diesel passenger car, by diesel combustion in a laboratory burner, and by evaporating and re-condensing lubrication oil were found to be very similar. The mass spectra from biomass burning particles show signatures identified as organic compounds like levoglucosan but also others which are yet unidentified. The aerodynamic behavior yielded a fractal dimension (Df) of 2.09 +/- 0.06 for biomass burning particles from the combustion of dry beech sticks, but showed values around three, and hence more compact particle morphologies, for particles from combustion of more natural oak. Scanning electron microscope images confirmed the finding that the beech combustion particles were fractal-like aggregates, while the oak combustion particles displayed a much more compact shape. For particles from laboratory combusted diesel fuel, a Df value of 2.35 was found, for spark soot particles, Df [approximate] 2.10. The aerodynamic properties of fractal-like particles from dry beech wood combustion indicate an aerodynamic shape factor [chi] that increases with electrical mobility diameter, and a bulk density of 1.92 g cm-3. An upper limit of [chi] [approximate] 1.2 was inferred for the shape factor of the more compact particles from oak combustion.

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.

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.

Multi-Hadron Observables from Lattice Quantum Chromodynamics

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

Hansen, Maxwell

2014-01-01

We describe formal work that relates the nite-volume spectrum in a quantum eld theory to scattering and decay amplitudes. This is of particular relevance to numerical calculations performed using Lattice Quantum Chromodynamics (LQCD). Correlators calculated using LQCD can only be determined on the Euclidean time axis. For this reason the standard method of determining scattering amplitudes via the Lehmann-Symanzik-Zimmermann reduction formula cannot be employed. By contrast, the nite-volume spectrum is directly accessible in LQCD calculations. Formalism for relating the spectrum to physical scattering observables is thus highly desirable. In this thesis we develop tools for extracting physical information from LQCDmore » for four types of observables. First we analyze systems with multiple, strongly-coupled two-scalar channels. Here we accommodate both identical and nonidentical scalars, and in the latter case allow for degenerate as well as nondegenerate particle masses. Using relativistic eld theory, and summing to all orders in perturbation theory, we derive a result relating the nite-volume spectrum to the two-to-two scattering amplitudes of the coupled-channel theory. This generalizes the formalism of Martin L uscher for the case of single-channel scattering. Second we consider the weak decay of a single particle into multiple, coupled two-scalar channels. We show how the nite-volume matrix element extracted in LQCD is related to matrix elements of asymptotic two-particle states, and thus to decay amplitudes. This generalizes work by Laurent Lellouch and Martin L uscher. Third we extend the method for extracting matrix elements by considering currents which insert energy, momentum and angular momentum. This allows one to extract transition matrix elements and form factors from LQCD. Finally we look beyond two-particle systems to those with three-particles in asymptotic states. Working again to all orders in relativistic eld theory, we derive a relation between the spectrum and an in nite-volume three-to-three scattering quantity. This nal analysis is the most complicated of the four, because the all-orders summation is more di cult for this system, and also because a number of new technical issues arise in analyzing the contributing diagrams.« less

The collisional Penrose process

NASA Astrophysics Data System (ADS)

Schnittman, Jeremy D.

2018-06-01

Shortly after the discovery of the Kerr metric in 1963, it was realized that a region existed outside of the black hole's event horizon where no time-like observer could remain stationary. In 1969, Roger Penrose showed that particles within this ergosphere region could possess negative energy, as measured by an observer at infinity. When captured by the horizon, these negative energy particles essentially extract mass and angular momentum from the black hole. While the decay of a single particle within the ergosphere is not a particularly efficient means of energy extraction, the collision of multiple particles can reach arbitrarily high center-of-mass energy in the limit of extremal black hole spin. The resulting particles can escape with high efficiency, potentially serving as a probe of high-energy particle physics as well as general relativity. In this paper, we briefly review the history of the field and highlight a specific astrophysical application of the collisional Penrose process: the potential to enhance annihilation of dark matter particles in the vicinity of a supermassive black hole.

Press Room

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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.

Science Fiction Stories with Reasonable Astronomy.

ERIC Educational Resources Information Center

Fraknoi, Andrew

1990-01-01

This resource list contains stories on the following topics: antimatter, asteroids, astronomers, black holes, comets, cosmology, jupiter, life elsewhere, mars, mercury, meteors, the moon, particle physics, pluto, quantum mechanics, quasars and active galaxies, relativity, saturn, stars, the sun, supernovae and neutron stars, time travel, uranus,…

Role of magnetic fields in physics and astrophysics; Proceedings of the Conference, Copenhagen, Denmark, June 5-7, 1974

NASA Technical Reports Server (NTRS)

Canuto, V.

1975-01-01

The papers deal with the role of magnetism in astrophysics and the properties of matter in the presence of unusually large magnetic fields. Topics include a quantum-mechanical treatment of high-energy charged particles radiating in a homogeneous magnetic field, the solution and properties of the Dirac equation for magnetic fields of any strength up to 10 to the 13th power gauss, experimental difficulties encountered and overcome in generating megagauss fields, the effect of strong radiation damping for an ultrarelativistic charge in an external electromagnetic field, magnetic susceptibilities of nuclei and elementary particles, and Compton scattering in strong external electromagnetic fields. Other papers examine static uniform electric and magnetic polarizabilities of the vacuum in arbitrarily strong magnetic fields, quantum-mechanical processes in neutron stars, basic ideas of mean-field magnetohydrodynamics, helical MHD turbulence, relations between cosmic and laboratory plasma physics, and insights into the nature of magnetism provided by relativity and cosmology. Individual items are announced in this issue.

Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest

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

Bateman, Adam P.; Gong, Zhaoheng; Harder, Tristan H.

The occurrence of nonliquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Measurements were conducted during two intensive operating periods (IOP1 and IOP2) that took place during the wet and dry seasons of the GoAmazon2014/5 campaign. Air masses representing variable influences of background conditions, urban pollution, and regional- and continental-scale biomass burning passed over the research site. As the air masses varied, particle rebound fraction, an indicator of physical state, was measured in real time at ground level using an impactor apparatus. Micrographs collected by transmission electron microscopymore » confirmed that liquid particles adhered, while nonliquid particles rebounded. Relative humidity (RH) was scanned to collect rebound curves. When the apparatus RH matched ambient RH, 95 % of the particles adhered as a campaign average. Secondary organic material, produced for the most part by the oxidation of volatile organic compounds emitted from the forest, produces liquid PM over this tropical forest. During periods of anthropogenic influence, by comparison, the rebound fraction dropped to as low as 60 % at 95 % RH. Analyses of the mass spectra of the atmospheric PM by positive-matrix factorization (PMF) and of concentrations of carbon monoxide, total particle number, and oxides of nitrogen were used to identify time periods affected by anthropogenic influences, including both urban pollution and biomass burning. The occurrence of nonliquid PM at high RH correlated with these indicators of anthropogenic influence. A linear model having as output the rebound fraction and as input the PMF factor loadings explained up to 70 % of the variance in the observed rebound fractions. Anthropogenic influences can contribute to the presence of nonliquid PM in the atmospheric particle population through the combined effects of molecular species that increase viscosity when internally mixed with background PM and increased concentrations of nonliquid anthropogenic particles in external mixtures of anthropogenic and biogenic PM.« less

Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest

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

Bateman, Adam P.; Gong, Zhaoheng; Harder, Tristan H.

The occurrence of non-liquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Measurements were conducted during two Intensive Operating Periods (IOP1 and IOP2) that took place during the wet and dry seasons, respectively, of the GoAmazon2014/5 campaign. Air masses representing variable influences of background conditions, urban pollution, and regional and continental scale biomass burning passed over the research site. As the air masses varied, particle rebound fraction, which is an indicator of the mix of physical states in a sampled particle population, was measured in real time atmore » ground level using an impactor apparatus. Micrographs collected by transmission electron microscopy confirmed that liquid particles adhered while non-liquid particles rebounded. Relative humidity (RH) was scanned to collect rebound curves. When the apparatus RH matched ambient RH, 95% of the particles were liquid as a campaign average, although this percentage dropped to as low as 60% during periods of anthropogenic influence. Secondary organic material, produced for the most part by the oxidation of volatile organic compounds emitted from the forest, was the largest source of liquid PM. Analyses of the mass spectra of the atmospheric PM by positive-matrix factorization (PMF) and of concentrations of carbon monoxide, total particle number, and oxides of nitrogen were used to identify time periods affected by anthropogenic influences, including both urban pollution and biomass burning. The occurrence of non-liquid PM correlated with these indicators of anthropogenic influence. A linear model having as output the rebound fraction and as input the PMF factor loadings explained up to 70% of the variance in the observed rebound fractions. Lastly, anthropogenic influences appear to favor non-liquid PM by providing molecular species that increase viscosity when internally mixed with background PM, by contributing non-liquid particles in external mixtures of PM, and a by combination of these effects under real-world conditions.« less

Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest

DOE PAGES

Bateman, Adam P.; Gong, Zhaoheng; Harder, Tristan H.; ...

2016-08-17

The occurrence of non-liquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Measurements were conducted during two Intensive Operating Periods (IOP1 and IOP2) that took place during the wet and dry seasons, respectively, of the GoAmazon2014/5 campaign. Air masses representing variable influences of background conditions, urban pollution, and regional and continental scale biomass burning passed over the research site. As the air masses varied, particle rebound fraction, which is an indicator of the mix of physical states in a sampled particle population, was measured in real time atmore » ground level using an impactor apparatus. Micrographs collected by transmission electron microscopy confirmed that liquid particles adhered while non-liquid particles rebounded. Relative humidity (RH) was scanned to collect rebound curves. When the apparatus RH matched ambient RH, 95% of the particles were liquid as a campaign average, although this percentage dropped to as low as 60% during periods of anthropogenic influence. Secondary organic material, produced for the most part by the oxidation of volatile organic compounds emitted from the forest, was the largest source of liquid PM. Analyses of the mass spectra of the atmospheric PM by positive-matrix factorization (PMF) and of concentrations of carbon monoxide, total particle number, and oxides of nitrogen were used to identify time periods affected by anthropogenic influences, including both urban pollution and biomass burning. The occurrence of non-liquid PM correlated with these indicators of anthropogenic influence. A linear model having as output the rebound fraction and as input the PMF factor loadings explained up to 70% of the variance in the observed rebound fractions. Lastly, anthropogenic influences appear to favor non-liquid PM by providing molecular species that increase viscosity when internally mixed with background PM, by contributing non-liquid particles in external mixtures of PM, and a by combination of these effects under real-world conditions.« less

Anthropogenic influences on the physical state of submicron particulate matter over a tropical forest

DOE PAGES

Bateman, Adam P.; Gong, Zhaoheng; Harder, Tristan H.; ...

2017-02-06

The occurrence of nonliquid and liquid physical states of submicron atmospheric particulate matter (PM) downwind of an urban region in central Amazonia was investigated. Measurements were conducted during two intensive operating periods (IOP1 and IOP2) that took place during the wet and dry seasons of the GoAmazon2014/5 campaign. Air masses representing variable influences of background conditions, urban pollution, and regional- and continental-scale biomass burning passed over the research site. As the air masses varied, particle rebound fraction, an indicator of physical state, was measured in real time at ground level using an impactor apparatus. Micrographs collected by transmission electron microscopymore » confirmed that liquid particles adhered, while nonliquid particles rebounded. Relative humidity (RH) was scanned to collect rebound curves. When the apparatus RH matched ambient RH, 95 % of the particles adhered as a campaign average. Secondary organic material, produced for the most part by the oxidation of volatile organic compounds emitted from the forest, produces liquid PM over this tropical forest. During periods of anthropogenic influence, by comparison, the rebound fraction dropped to as low as 60 % at 95 % RH. Analyses of the mass spectra of the atmospheric PM by positive-matrix factorization (PMF) and of concentrations of carbon monoxide, total particle number, and oxides of nitrogen were used to identify time periods affected by anthropogenic influences, including both urban pollution and biomass burning. The occurrence of nonliquid PM at high RH correlated with these indicators of anthropogenic influence. A linear model having as output the rebound fraction and as input the PMF factor loadings explained up to 70 % of the variance in the observed rebound fractions. Anthropogenic influences can contribute to the presence of nonliquid PM in the atmospheric particle population through the combined effects of molecular species that increase viscosity when internally mixed with background PM and increased concentrations of nonliquid anthropogenic particles in external mixtures of anthropogenic and biogenic PM.« less

Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Kim, Jaeseok; Yoon, Young Jun; Gim, Yeontae; Kang, Hyo Jin; Choi, Jin Hee; Park, Ki-Tae; Lee, Bang Yong

2017-11-01

Seasonal variability in the physical characteristics of aerosol particles sampled from the King Sejong Station in the Antarctic Peninsula was investigated over the period between March 2009 and February 2015. Clear seasonal cycles for the total particle concentration (CN) were observed. The mean monthly concentration of particles larger than 2.5 nm (CN2.5) was highest during the austral summer, with an average value of 1080.39 ± 595.05 cm-3, and lowest during the austral winter, with a mean value of 197.26 ± 71.71 cm-3. The seasonal patterns in the concentrations of cloud condensation nuclei (CCN) and CN coincide, with both concentrations being at a minimum in winter and maximum in summer. The measured CCN spectra were approximated by fitting a power-law function relating the number of CCN for a given supersaturation (SS) to each SS value, with fitting coefficients C and kT. The values for C varied from 6.35 to 837.24 cm-3, with a mean of 171.48 ± 62.00 cm-3. The values for kT ranged from 0.07 to 2.19, with a mean of 0.41 ± 0.10. In particular, the kT values during the austral summer were higher than those during the winter, indicating that aerosol particles are more sensitive to SS changes during summer. Furthermore, the annual mean hygroscopicity parameter, κ, was estimated as 0.15 ± 0.05, for a SS of 0.4 %. The effects of the origin and pathway travelled by the air mass on the physical characteristics of the aerosol particles were also determined. The modal diameter of aerosol particles originating in the South Pacific Ocean showed a seasonal variation varying from 0.023 µm in winter to 0.034 µm in summer for the Aitken mode, and from 0.086 µm in winter to 0.109 µm in summer for the accumulation mode.

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.

Effect of New Physics in Astrophysical Neutrino Flavor.

PubMed

Argüelles, Carlos A; Katori, Teppei; Salvado, Jordi

2015-10-16

Astrophysical neutrinos are powerful tools for investigating the fundamental properties of particle physics through their flavor content. In this Letter, we perform the first general new physics study on ultrahigh energy neutrino flavor content by introducing effective operators. We find that, at the current limits on these operators, new physics terms cause maximal effects on the flavor content; however, the flavor content on the Earth is confined to a region related to the assumed initial flavor content. Furthermore, we conclude that a precise measure of the flavor content on the Earth will provide orders of magnitude improvement on new physics bounds. Finally, we discuss the current best fits of flavor content of the IceCube data and their interplay with new physics scenarios.

Software-aided discussion about classical picture of Mach-Zehnder interferometer

NASA Astrophysics Data System (ADS)

Cavalcanti, C. J. H.; Ostermann, F.; Lima, N. W.; Netto, J. S.

2017-11-01

The Mach-Zehnder interferometer has played an important role both in quantum and classical physics research over the years. In physics education, it has been used as a didactic tool for quantum physics teaching, allowing fundamental concepts, such as particle-wave duality, to be addressed from the very beginning. For a student to understand the novelties of the quantum scenario, it is first worth introducing the classical picture. In this paper, we introduce a new version of the software developed by our research group to deepen the discussion on the classical picture of the Mach-Zehnder interferometer. We present its equivalence with the double slit experiment and we derive the mathematical expressions relating to the interference pattern. We also explore the concept of visibility (which is very important for understanding wave-particle complementarity in quantum physics) to help students become familiar with this experiment and to enhance their knowledge of its counterintuitive aspects. We use the software articulated by the mathematical formalism and phenomenological features. We also present excerpts of the discursive interactions of students using the software in didactic situations.

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

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.

Implications of the {{\\boldsymbol{R}}}_{K} and {{\\boldsymbol{R}}}_{{K}^{* }} anomalies

NASA Astrophysics Data System (ADS)

Wang, Wei; Zhao, Shuai

2018-01-01

We discuss the implications of the recently reported {R}{{K}} and {R}{{{K}}* } anomalies, the lepton flavor non-universality in the {{B}}\\to {Kl}}+{{{l}}}- and {{B}}\\to {{{K}}}* {{{l}}}+{{{l}}}- decay channels. Using two sets of hadronic inputs of form factors, we perform a fit of new physics to the {R}{{K}} and {R}{{{K}}* } data, and significant new physics contributions are found. We suggest the study of lepton flavor universality in a number of related rare {{B}},{{{B}}}s,{{{B}}}c and {{{Λ }}}{{b}} decay channels, and in particular we give predictions for the {{μ }}-to-e ratios of decay widths with different polarizations of the final state particles, and of the {{b}}\\to {dl}}+{{{l}}}- processes, which are presumably more sensitive to the structure of the underlying new physics. With the new physics contributions embedded in the Wilson coefficients, we present theoretical predictions for lepton flavor non-universality in these processes. Supported by National Natural Science Foundation of China (11575110, 11655002, 11735010), Natural Science Foundation of Shanghai (15DZ2272100, 15ZR1423100), Young Thousand Talents Plan and Key Laboratory for Particle Physics, Astrophysics and Cosmology, Ministry of Education

Statistical physics of vehicular traffic and some related systems

NASA Astrophysics Data System (ADS)

Chowdhury, Debashish; Santen, Ludger; Schadschneider, Andreas

2000-05-01

In the so-called “microscopic” models of vehicular traffic, attention is paid explicitly to each individual vehicle each of which is represented by a “particle”; the nature of the “interactions” among these particles is determined by the way the vehicles influence each others’ movement. Therefore, vehicular traffic, modeled as a system of interacting “particles” driven far from equilibrium, offers the possibility to study various fundamental aspects of truly nonequilibrium systems which are of current interest in statistical physics. Analytical as well as numerical techniques of statistical physics are being used to study these models to understand rich variety of physical phenomena exhibited by vehicular traffic. Some of these phenomena, observed in vehicular traffic under different circumstances, include transitions from one dynamical phase to another, criticality and self-organized criticality, metastability and hysteresis, phase-segregation, etc. In this critical review, written from the perspective of statistical physics, we explain the guiding principles behind all the main theoretical approaches. But we present detailed discussions on the results obtained mainly from the so-called “particle-hopping” models, particularly emphasizing those which have been formulated in recent years using the language of cellular automata.

Source and Health Implication of Diurnal Atmospheric PM Mass and Number Concentrations

NASA Astrophysics Data System (ADS)

Li, W.; Olvera, H. A.; Garcia, J. H.; Pingitore, N. E.

2007-12-01

Exposure to atmospheric PM has been known to be associated with adverse health effects, decreased heart-rate variability, and respiratory and cardiopulmonary related morbidity and mortality. New evidence suggests that physical characteristics (mass, size, number, surface area, and morphology) of particles are strongly associated with mortality and morbidity through acute exposure. In particular, as reported in the literature, fine or ultrafine particles are more toxic than coarse particles on an equivalent mass basis while particles of less than 30 nm or greater than 2.5 um in diameter deposit more effectively (approximately 80 percent) in lung versus approximately 18 percent for particles in the range of 100 nm and 1 um. In addition, positive association has been observed between day to day variation in PM2.5 and hospital admissions, mortality and particle surface area, or particle number concentration and oxidative stress-induced DNA damage. This presentation shows the results of a study characterizing the physical properties of PM in El Paso, Texas. Diurnal PM mass concentration peaks previously observed at several other cities along the U.S.-Mexico border and elsewhere in the world were observed in El Paso. The hourly PM particle count varied from less than 10,000 particles/cm3 to greater than 80,000 particles/cm3 during the diurnal PM mass peaks. The total number of PM particles peaked in the morning and in the evening while the mode of the particle size changed from 20 nm to 50 nm, indicating different PM sources may be responsible for the mass and number concentrations and agglomeration of particles in the atmosphere during the day may possibly plays a role. A multivariate regression analysis was performed to correlate the PM mass and number concentrations to environmental variables. Real- time wind statistics were used in conjunction with traffic data at a nearby highway for identifying sources of the PM mass and number concentration peaks. Evaluation of the diurnal variation of PM physical properties and a recent study on PM mass and mortality implies that particle number may be a better environmental indicator for mortality than PM2.5 mass. This publication was made possible by grant number 1 S11 ES013339-01A1 from the National Institute of Environmental Health Sciences (NIEHS), NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS, NIH.

The effect of gas physics on the halo mass function

NASA Astrophysics Data System (ADS)

Stanek, R.; Rudd, D.; Evrard, A. E.

2009-03-01

Cosmological tests based on cluster counts require accurate calibration of the space density of massive haloes, but most calibrations to date have ignored complex gas physics associated with halo baryons. We explore the sensitivity of the halo mass function to baryon physics using two pairs of gas-dynamic simulations that are likely to bracket the true behaviour. Each pair consists of a baseline model involving only gravity and shock heating, and a refined physics model aimed at reproducing the observed scaling of the hot, intracluster gas phase. One pair consists of billion-particle resimulations of the original 500h-1Mpc Millennium Simulation of Springel et al., run with the smoothed particle hydrodynamics (SPH) code GADGET-2 and using a refined physics treatment approximated by pre-heating (PH) at high redshift. The other pair are high-resolution simulations from the adaptive-mesh refinement code ART, for which the refined treatment includes cooling, star formation and supernova feedback (CSF). We find that, although the mass functions of the gravity-only (GO) treatments are consistent with the recent calibration of Tinker et al. (2008), both pairs of simulations with refined baryon physics show significant deviations. Relative to the GO case, the masses of ~1014h-1Msolar haloes in the PH and CSF treatments are shifted by the averages of -15 +/- 1 and +16 +/- 2 per cent, respectively. These mass shifts cause ~30 per cent deviations in number density relative to the Tinker function, significantly larger than the 5 per cent statistical uncertainty of that calibration.

Quantum Consciousness - The Road to Reality

NASA Astrophysics Data System (ADS)

Goradia, Shantilal

Per Einstein's theory mass tells space how to curve and space tells mass how to move. How do they tell\\x9D? The question boils down to information created by quantum particles blinking ON and OFF analogous to 'Ying and Yang' or some more complex ways that may include dark matter. Consciousness, dark matter, quantum physics, uncertainty principle, constants of nature like strong coupling, fine structure constant, cosmological constant introduced by Einstein, information, gravitation etc. are fundamentally consequences of that ONE TOE. Vedic philosophers, who impressed Schrodinger so much, called it ATMA split in the categories of AnuAtma (particle soul), JivAtma (life soul) and ParamAtma (Omnipresent soul) which we relate to quantum physics, biology and cosmology. There is no separate TOE (Theory of Everything) for any one thing.

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

NASA Astrophysics Data System (ADS)

Machleidt, Ruprecht

2006-05-01

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

Ontic structural realism and quantum field theory: Are there intrinsic properties at the most fundamental level of reality?

NASA Astrophysics Data System (ADS)

Berghofer, Philipp

2018-05-01

Ontic structural realism refers to the novel, exciting, and widely discussed basic idea that the structure of physical reality is genuinely relational. In its radical form, the doctrine claims that there are, in fact, no objects but only structure, i.e., relations. More moderate approaches state that objects have only relational but no intrinsic properties. In its most moderate and most tenable form, ontic structural realism assumes that at the most fundamental level of physical reality there are only relational properties. This means that the most fundamental objects only possess relational but no non-reducible intrinsic properties. The present paper will argue that our currently best physics refutes even this most moderate form of ontic structural realism. More precisely, I will claim that 1) according to quantum field theory, the most fundamental objects of matter are quantum fields and not particles, and show that 2) according to the Standard Model, quantum fields have intrinsic non-relational properties.

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.

Composition and mixing states of brown haze particle over the Himalayas along two transboundary south-north transects

NASA Astrophysics Data System (ADS)

Dong, Zhiwen; Kang, Shichang; Guo, Junming; Zhang, Qianggong; Wang, Xuejia; Qin, Dahe

2017-05-01

Pollutants that are usually transported from southern Asia to the Tibetan Plateau deposit on the Plateau surface, change snow albedo and thereby surface radiative flux. This results numerous climatic implications like as erratic monsoon, perturbation in hydrological cycle, etc. However, the accurate estimation of these climatic implications is not well understood, because the atmospheric pollution is a heterogeneous mixture of various particle types. Therefore, this part of climate research requires a detailed investigation of physical and chemical properties of atmospheric pollutants. This study aimed to examine the physical and chemical properties of atmospheric pollutants across the Himalayan regions along two transboundary south-north transects. The information of individual-particles was obtained using microscopy-based techniques that comprises transmission electron microscope (TEM) and Energy-dispersive X-ray spectrometer (EDX). Study capture the signatures of various types of atmospheric species such as black carbon (BC), mineral dust, fly ash, organic matter, sulfate, nitrite, ammonium, and NaCl. Microscopy-based techniques confirm that these particles were generally in mixing state, for example salt-coated particles accounting for 25-56% of the total particles in sampled locations. Our analysis shows that urban and rural locations are characterized with atmospheric particles which sourced from anthropogenic activities, whereas remote locations with those released from natural crustal. However, the relative contributions of anthropogenic particles were higher than that of particles released from natural crustal. The presence of such particles over remote locations of Himalayan region provides an evidence of prevailing atmospheric transport processes, which further need to be well understood. It is expected that this work would be helpful in understanding the regional atmospheric conditions and the transboundary transport process of haze particles. As these informations are of great importance in modeling studies, which further lead to improve understanding of haze particles climate effects.

Detectors for Linear Colliders: Calorimetry at a Future Electron-Positron Collider (3/4)

ScienceCinema

Thomson, Mark

2018-04-16

Calorimetry will play a central role in determining the physics reach at a future e+e- collider. The requirements for calorimetry place the emphasis on achieving an excellent jet energy resolution. The currently favoured option for calorimetry at a future e+e- collider is the concept of high granularity particle flow calorimetry. Here granularity and a high pattern recognition capability is more important than the single particle calorimetric response. In this lecture I will describe the recent progress in understanding the reach of high granularity particle flow calorimetry and the related R&D; efforts which concentrate on test beam demonstrations of the technological options for highly granular calorimeters. I will also discuss alternatives to particle flow, for example the technique of dual readout calorimetry.

A 3D particle Monte Carlo approach to studying nucleation

NASA Astrophysics Data System (ADS)

Köhn, Christoph; Enghoff, Martin Bødker; Svensmark, Henrik

2018-06-01

The nucleation of sulphuric acid molecules plays a key role in the formation of aerosols. We here present a three dimensional particle Monte Carlo model to study the growth of sulphuric acid clusters as well as its dependence on the ambient temperature and the initial particle density. We initiate a swarm of sulphuric acid-water clusters with a size of 0.329 nm with densities between 107 and 108 cm-3 at temperatures between 200 and 300 K and a relative humidity of 50%. After every time step, we update the position of particles as a function of size-dependent diffusion coefficients. If two particles encounter, we merge them and add their volumes and masses. Inversely, we check after every time step whether a polymer evaporates liberating a molecule. We present the spatial distribution as well as the size distribution calculated from individual clusters. We also calculate the nucleation rate of clusters with a radius of 0.85 nm as a function of time, initial particle density and temperature. The nucleation rates obtained from the presented model agree well with experimentally obtained values and those of a numerical model which serves as a benchmark of our code. In contrast to previous nucleation models, we here present for the first time a code capable of tracing individual particles and thus of capturing the physics related to the discrete nature of particles.

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.

Millikan Award Lecture, 2006: Physics For All

NASA Astrophysics Data System (ADS)

Hobson, Art

2006-12-01

We physics teachers must broaden our focus from physics for physicists and other scientists to physics for all. The reason, as the American Association for the Advancement of Science puts it, is that "[w]ithout a scientifically literate population, the outlook for a better world is not promising." Physics for all (including the first course for scientists) should be conceptual, not technical. It should describe the universe as we understand it today, including special and general relativity, quantum physics, modern cosmology, nuclear physics, the standard model of particles and interactions, and quantum fields. Many science writers have shown that this description is possible. It should emphasize the scientific process and include such societal topics as global warming, nuclear weapons, and pseudoscience, because citizens need to vote intelligently on such issues.

Effects of compressibility on turbulent relative particle dispersion

NASA Astrophysics Data System (ADS)

Shivamoggi, Bhimsen K.

2016-08-01

In this paper, phenomenological developments are used to explore the effects of compressibility on the relative particle dispersion (RPD) in three-dimensional (3D) fully developed turbulence (FDT). The role played by the compressible FDT cascade physics underlying this process is investigated. Compressibility effects are found to lead to reduction of RPD, development of the ballistic regime and particle clustering, corroborating the laboratory experiment and numerical simulation results (Cressman J. R. et al., New J. Phys., 6 (2004) 53) on the motion of Lagrangian tracers on a surface flow that constitutes a 2D compressible subsystem. These formulations are developed from the scaling relations for compressible FDT and are validated further via an alternative dimensional/scaling development for compressible FDT similar to the one given for incompressible FDT by Batchelor and Townsend (Surveys in Mechanics (Cambridge University Press) 1956, p. 352). The rationale for spatial intermittency effects is legitimized via the nonlinear scaling dependence of RPD on the kinetic-energy dissipation rate.

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.

Precise measurement of the {sup 19}Ne half-life

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

Triambak, S.; TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3

2011-11-30

We describe a high-precision measurement of the half-life of the T = 1/2 nucleus {sup 19}Ne, performed at TRIUMF, Canada's National Laboratory for Nuclear and Particle Physics, Vancouver, Canada. Some implications of this measurement related to tests of the Standard Model are discussed.

Project Physics Handbook 6, The Nucleus.

ERIC Educational Resources Information Center

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

Five experiments and nine activities are presented in this Unit 6 handbook. The experiments are related to random events, ranges of alpha and beta particles, half-lives, and radioactive tracers. The activities are concerned with the energy measurement in beta radiation, demonstration with sugar cubes, ionization by radioactivity, magnetic…

PARTICIPATION IN HIGH ENERGY PHYSICS

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

White, Christopher

2012-12-20

This grant funded experimental and theoretical activities in elementary particles physics at the Illinois Institute of Technology (IIT). The experiments in which IIT faculty collaborated included the Daya Bay Reactor Neutrino Experiment, the MINOS experiment, the Double Chooz experiment, and FNAL E871 - HyperCP experiment. Funds were used to support summer salary for faculty, salary for postdocs, and general support for graduate and undergraduate students. Funds were also used for travel expenses related to these projects and general supplies.

Morphology and mixing state of individual freshly emitted wildfire carbonaceous particles.

PubMed

China, Swarup; Mazzoleni, Claudio; Gorkowski, Kyle; Aiken, Allison C; Dubey, Manvendra K

2013-01-01

Biomass burning is one of the largest sources of carbonaceous aerosols in the atmosphere, significantly affecting earth's radiation budget and climate. Tar balls, abundant in biomass burning smoke, absorb sunlight and have highly variable optical properties, typically not accounted for in climate models. Here we analyse single biomass burning particles from the Las Conchas fire (New Mexico, 2011) using electron microscopy. We show that the relative abundance of tar balls (80%) is 10 times greater than soot particles (8%). We also report two distinct types of tar balls; one less oxidized than the other. Furthermore, the mixing of soot particles with other material affects their optical, chemical and physical properties. We quantify the morphology of soot particles and classify them into four categories: ~50% are embedded (heavily coated), ~34% are partly coated, ~12% have inclusions and~4% are bare. Inclusion of these observations should improve climate model performances.

Jamming and Localization of Interacting Run-and-Tumble Particles

NASA Astrophysics Data System (ADS)

Blythe, Richard; Evans, Martin; Slowman, Alexander

Certain species of bacteria, notably Escherichia coli, exhibit a characteristic run-and-tumble motion comprising a sequence of straight-line runs at constant velocity interspersed with tumble events that randomize the direction of motion. In a many-body setting, this nonequilibrium dynamics can generate the phenomenon of motility-induced phase separation, which is also seen for a wide variety of self-propelled particles more generally. Whilst the propensity of self-propelled particles to phase separate is understood at a mesoscopic level, the origin of this behaviour in the inelastic collisions between particles implied by the microscopic dynamics is not. Here we present exact results for run-and-tumble particles in one dimension that reveal a richly-structured stationary state that comprises a superposition of three distinct physical states whose relative weights vary with the run and tumble rates, namely a jammed state, a localized state and a delocalized state.

Actinide migration in Johnston Atoll soil

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

Wolf, S. F.; Bates, J. K.; Buck, E. C.

1997-02-01

Characterization of the actinide content of a sample of contaminated coral soil from Johnston Atoll, the site of three non-nuclear destructs of nuclear warhead-carrying THOR missiles in 1962, revealed that >99% of the total actinide content is associated with discrete bomb fragments. After removal of these fragments, there was an inverse correlation between actinide content and soil particle size in particles from 43 to 0.4 {micro}m diameter. Detailed analyses of this remaining soil revealed no discrete actinide phase in these soil particles, despite measurable actinide content. Observations indicate that exposure to the environment has caused the conversion of relatively insolublemore » actinide oxides to the more soluble actinyl oxides and actinyl carbonate coordinated complexes. This process has led to dissolution of actinides from discrete particles and migration to the surrounding soil surfaces, resulting in a dispersion greater than would be expected by physical transport of discrete particles alone.« less

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.

Thermodynamics Of Common Atmospheric Particles On The Nanoscale

NASA Astrophysics Data System (ADS)

Onasch, T.; Han, J.; Oatis, S.; Brechtel, F.; Imre, D. G.

2002-12-01

A significant fraction of atmospheric particles are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence. Recent field studies have observed large nucleation events of hygroscopic particles and note discrepancies between predicted and observed particle growth rates after nucleation. These growth rates are governed, in part, by the thermodynamic properties of particles only a few nanometers in diameter. However, little thermodynamic information is currently available for nanometer?sized particles. The Kelvin relation indicates that the surface tension of a particle less than 100nm in diameter can dramatically affect the thermodynamics, and surface states may begin to influence the bulk physical properties in these small particles with high surface to volume ratios. In this context, we are investigating the thermodynamic properties, including pre-deliquescence water adsorption, deliquescence, efflorescence, and supersaturated particle compositions of nanoparticles with mobility diameters in the range of 5 to 50 nm. We have developed a temperature and humidity-controlled laboratory-based Nano Differential Mobility Analyzer (NDMA) system to characterize the hygroscopic properties of the common atmospheric salt particles as a function of size. Two different aerosol generation systems have been used to cover the full size range. The first system (less than 20nm diameter) relies on an Atomizer (TSI 3076) to produce particles which are size?selected using an initial DMA. For particle sizes smaller than 20 nm, the Electrospray Aerosol Generator (EAG, TSI 3480) has been employed as a particle source. The EAG characteristically provides narrow size distributions, comparable to the monodisperse size distribution from a DMA, but with higher number concentrations. Once generated, the monodisperse aerosol flow is then conditioned with respect to humidity at a constant temperature and subsequently analyzed using a TSI Ultrafine CPC (Model 3010) modified for Pulse-Height Analysis. The dry particle sizes are also continually monitored by an external SMPS system (TSI 3936) to rectify errors in the calculated growth factor resulting from any drift in the dry particle size. The size changes of the humidified particles are directly correlated with the relative humidity and temperature. Our results of ammonium sulfate particles from 5 - 50 nm in diameter are consistent with those predicted from the Kelvin relation. The particle size affects both deliquescence and efflorescence of the homogeneous salt particles: the deliquescence relative humidity increases and the efflorescence decreases as particles become smaller. In addition, although the smaller the particle size the more significant water adsorption, the sharp deliquescence phase transition was obvious regardless of the particle sizes. The implications with respect to these observations will be further discussed at the presentation.

Gyrokinetic Particle Simulation of Turbulent Transport in Burning Plasmas (GPS - TTBP) Final Report

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

Chame, Jacqueline

2011-05-27

The goal of this project is the development of the Gyrokinetic Toroidal Code (GTC) Framework and its applications to problems related to the physics of turbulence and turbulent transport in tokamaks,. The project involves physics studies, code development, noise effect mitigation, supporting computer science efforts, diagnostics and advanced visualizations, verification and validation. Its main scientific themes are mesoscale dynamics and non-locality effects on transport, the physics of secondary structures such as zonal flows, and strongly coherent wave-particle interaction phenomena at magnetic precession resonances. Special emphasis is placed on the implications of these themes for rho-star and current scalings and formore » the turbulent transport of momentum. GTC-TTBP also explores applications to electron thermal transport, particle transport; ITB formation and cross-cuts such as edge-core coupling, interaction of energetic particles with turbulence and neoclassical tearing mode trigger dynamics. Code development focuses on major initiatives in the development of full-f formulations and the capacity to simulate flux-driven transport. In addition to the full-f -formulation, the project includes the development of numerical collision models and methods for coarse graining in phase space. Verification is pursued by linear stability study comparisons with the FULL and HD7 codes and by benchmarking with the GKV, GYSELA and other gyrokinetic simulation codes. Validation of gyrokinetic models of ion and electron thermal transport is pursed by systematic stressing comparisons with fluctuation and transport data from the DIII-D and NSTX tokamaks. The physics and code development research programs are supported by complementary efforts in computer sciences, high performance computing, and data management.« less

A Hybrid Physics-Based Data-Driven Approach for Point-Particle Force Modeling

NASA Astrophysics Data System (ADS)

Moore, Chandler; Akiki, Georges; Balachandar, S.

2017-11-01

This study improves upon the physics-based pairwise interaction extended point-particle (PIEP) model. The PIEP model leverages a physical framework to predict fluid mediated interactions between solid particles. While the PIEP model is a powerful tool, its pairwise assumption leads to increased error in flows with high particle volume fractions. To reduce this error, a regression algorithm is used to model the differences between the current PIEP model's predictions and the results of direct numerical simulations (DNS) for an array of monodisperse solid particles subjected to various flow conditions. The resulting statistical model and the physical PIEP model are superimposed to construct a hybrid, physics-based data-driven PIEP model. It must be noted that the performance of a pure data-driven approach without the model-form provided by the physical PIEP model is substantially inferior. The hybrid model's predictive capabilities are analyzed using more DNS. In every case tested, the hybrid PIEP model's prediction are more accurate than those of physical PIEP model. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1315138 and the U.S. DOE, NNSA, ASC Program, as a Cooperative Agreement under Contract No. DE-NA0002378.

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

Acoustic impedance properties of seafloor sediments off the coast of Southeastern Hainan, South China Sea

NASA Astrophysics Data System (ADS)

Hou, Zhengyu; Chen, Zhong; Wang, Jingqiang; Zheng, Xufeng; Yan, Wen; Tian, Yuhang; Luo, Yun

2018-04-01

Geoacoustic parameters are essential inputs to sediment wave propagation theories and are vital to underwater acoustic environment and explorations of the sea bottom. In this study, 21 seafloor sediment samples were collected off the coast of southeastern Hainan in the South China Sea. The sound speed was measured using a portable WSD-3 digital sonic instrument and the coaxial differential distance measurement method. Based on the measured sound speed and physical properties, the acoustic impedance and the pore-water-independent index of impedance (IOI) were calculated in this study. Similar to the sound speed, the IOI values are closely related to the sediment physical properties and change gradually from the northwest to the southeast. The relations between IOI and physical properties were studied and compared to the relations between the sound speed and physical properties. IOI is better correlated to physical properties than sound speed. This study also uses an error norm method to analyze the sensitivity of IOI to the physical parameters in the double-parameter equations and finds that the most influential physical parameters are as follows: wet bulk density > porosity > clay content > mean particle size.

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.

Optofluidics incorporating actively controlled micro- and nano-particles

PubMed Central

Kayani, Aminuddin A.; Khoshmanesh, Khashayar; Ward, Stephanie A.; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2012-01-01

The advent of optofluidic systems incorporating suspended particles has resulted in the emergence of novel applications. Such systems operate based on the fact that suspended particles can be manipulated using well-appointed active forces, and their motions, locations and local concentrations can be controlled. These forces can be exerted on both individual and clusters of particles. Having the capability to manipulate suspended particles gives users the ability for tuning the physical and, to some extent, the chemical properties of the suspension media, which addresses the needs of various advanced optofluidic systems. Additionally, the incorporation of particles results in the realization of novel optofluidic solutions used for creating optical components and sensing platforms. In this review, we present different types of active forces that are used for particle manipulations and the resulting optofluidic systems incorporating them. These systems include optical components, optofluidic detection and analysis platforms, plasmonics and Raman systems, thermal and energy related systems, and platforms specifically incorporating biological particles. We conclude the review with a discussion of future perspectives, which are expected to further advance this rapidly growing field. PMID:23864925

Comparison of GEANT4 Physics Models with Measured Beta Particle Data in Aluminum using a Strontium-90 Source

NASA Astrophysics Data System (ADS)

Everett, Samantha

2010-10-01

A transmission curve experiment was carried out to measure the range of beta particles in aluminum in the health physics laboratory located on the campus of Texas Southern University. The transmission count rate through aluminum for varying radiation lengths was measured using beta particles emitted from a low activity (˜1 μCi) Sr-90 source. The count rate intensity was recorded using a Geiger Mueller tube (SGC N210/BNC) with an active volume of 61 cm^3 within a systematic detection accuracy of a few percent. We compared these data with a realistic simulation of the experimental setup using the Geant4 Monte Carlo toolkit (version 9.3). The purpose of this study was to benchmark our Monte Carlo for future experiments as part of a more comprehensive research program. Transmission curves were simulated based on the standard and low-energy electromagnetic physics models, and using the radioactive decay module for the electrons primary energy distribution. To ensure the validity of our measurements, linear extrapolation techniques were employed to determine the in-medium beta particle range from the measured data and was found to be 1.87 g/cm^2 (˜0.693 cm), in agreement with literature values. We found that the general shape of the measured data and simulated curves were comparable; however, a discrepancy in the relative count rates was observed. The origin of this disagreement is still under investigation.

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.

Three-body correlations and conditional forces in suspensions of active hard disks

NASA Astrophysics Data System (ADS)

Härtel, Andreas; Richard, David; Speck, Thomas

2018-01-01

Self-propelled Brownian particles show rich out-of-equilibrium physics, for instance, the motility-induced phase separation (MIPS). While decades of studying the structure of liquids have established a deep understanding of passive systems, not much is known about correlations in active suspensions. In this work we derive an approximate analytic theory for three-body correlations and forces in systems of active Brownian disks starting from the many-body Smoluchowski equation. We use our theory to predict the conditional forces that act on a tagged particle and their dependence on the propulsion speed of self-propelled disks. We identify preferred directions of these forces in relation to the direction of propulsion and the positions of the surrounding particles. We further relate our theory to the effective swimming speed of the active disks, which is relevant for the physics of MIPS. To test and validate our theory, we additionally run particle-resolved computer simulations, for which we explicitly calculate the three-body forces. In this context, we discuss the modeling of active Brownian swimmers with nearly hard interaction potentials. We find very good agreement between our simulations and numerical solutions of our theory, especially for the nonequilibrium pair-distribution function. For our analytical results, we carefully discuss their range of validity in the context of the different levels of approximation we applied. This discussion allows us to study the individual contribution of particles to three-body forces and to the emerging structure. Thus, our work sheds light on the collective behavior, provides the basis for further studies of correlations in active suspensions, and makes a step towards an emerging liquid state theory.

Gravity beyond Einstein? Part I: Physics and the Trouble with Experiments

NASA Astrophysics Data System (ADS)

Hauser, Jochem; Dröscher, Walter

2017-05-01

This article provides a review of the latest experimental results in quantum physics and astrophysics, discussing their repercussions on the advanced physical theories that go beyond both the SMs (standard models) of particle physics and cosmology. It will be shown that many of the essential concepts of the advanced theoretical models developed over the past 40 years are no longer tenable because they are contradicting the novel data. Most recent results (December 2016) from the Large Hadron Collider revealed no new matter particles up to particle masses of 1.6 TeV/c2, which is in accordance with recent ACME experimental data (2014) that saw no electric dipole moment for the electron as predicted by these theories. Moreover, the LUX experiment (since 2013) did not see any dark matter particles either, thus independently supporting LHC and ACME measurements. Furthermore, experimental particle physics seems to be telling us that dark matter particles (LHC results) do not exist, suggesting that dark matter particles either are more exotic or are more difficult to detect than had been predicted in the past decades (less likely with recent LHC results). Astrophysical observations since 1933, starting with Caltech astronomer Zwicky, however, have provided irrefutable evidence for the existence of dark matter, for instance, based on the phenomenon of gravitational lensing as well as observed rotational velocities of stars orbiting the galactic center that are deviating from Newton's law. Surprisingly, recent astronomical observations by Bidin, ESO (2010, 2012, 2014), seem to indicate the absence of dark matter within galaxies. In addition, cosmology at present has no explanation for about 68 % of the energy in the Universe that comes in the form of dark energy. Recently, measured data from three entirely different types of experiments both on earth and in space (2006-2011) are hinting at completely novel features of gravity that, if confirmed, must be outside Einstein's general relativity. Extreme gravitomagnetic and gravity-like fields may have been observed at cryogenic temperatures generated by a rotating ring or disk. However, these experimental results are not conclusive so far. The strength of these extreme fields has been calculated and, according to the respective equations, should be sufficient to serve as a basis for a gravitational technology that, for example, could establish long sought field propulsion (i.e. propulsion without fuel), actively researched by physicists and rocket engineers in the 1960s and 1990s. This article concludes with an outlook on the novel technology of gravitational engineering that might follow from gravity-like fields and discusses the novel physical concepts resulting from the existence of these extreme gravitomagnetic fields.

A Physical Model to Estimate Snowfall over Land using AMSU-B Observations

NASA Technical Reports Server (NTRS)

Kim, Min-Jeong; Weinman, J. A.; Olson, W. S.; Chang, D.-E.; Skofronick-Jackson, G.; Wang, J. R.

2008-01-01

In this study, we present an improved physical model to retrieve snowfall rate over land using brightness temperature observations from the National Oceanic and Atmospheric Administration's (NOAA) Advanced Microwave Sounder Unit-B (AMSU-B) at 89 GHz, 150 GHz, 183.3 +/- 1 GHz, 183.3 +/- 3 GHz, and 183.3 +/- 7 GHz. The retrieval model is applied to the New England blizzard of March 5, 2001 which deposited about 75 cm of snow over much of Vermont, New Hampshire, and northern New York. In this improved physical model, prior retrieval assumptions about snowflake shape, particle size distributions, environmental conditions, and optimization methodology have been updated. Here, single scattering parameters for snow particles are calculated with the Discrete-Dipole Approximation (DDA) method instead of assuming spherical shapes. Five different snow particle models (hexagonal columns, hexagonal plates, and three different kinds of aggregates) are considered. Snow particle size distributions are assumed to vary with air temperature and to follow aircraft measurements described by previous studies. Brightness temperatures at AMSU-B frequencies for the New England blizzard are calculated using these DDA calculated single scattering parameters and particle size distributions. The vertical profiles of pressure, temperature, relative humidity and hydrometeors are provided by MM5 model simulations. These profiles are treated as the a priori data base in the Bayesian retrieval algorithm. In algorithm applications to the blizzard data, calculated brightness temperatures associated with selected database profiles agree with AMSU-B observations to within about +/- 5 K at all five frequencies. Retrieved snowfall rates compare favorably with the near-concurrent National Weather Service (NWS) radar reflectivity measurements. The relationships between the NWS radar measured reflectivities Z(sub e) and retrieved snowfall rate R for a given snow particle model are derived by a histogram matching technique. All of these Z(sub e)-R relationships fall in the range of previously established Z(sub e)-R relationships for snowfall. This suggests that the current physical model developed in this study can reliably estimate the snowfall rate over land using the AMSU-B measured brightness temperatures.

TU-G-BRB-04: Digital Phantoms for Developing Protocols in Particle Therapy

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

Lee, C.

2015-06-15

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

TU-G-BRB-02: Clinical Trials in Particle Therapy - Open Questions

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

Choy, H.

2015-06-15

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

TU-G-BRB-00: Clinical Trials in Proton and Particle Therapy

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

NONE

2015-06-15

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

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.

Regular threshold-energy increase with charge for neutral-particle emission in collisions of electrons with oligonucleotide anions.

PubMed

Tanabe, T; Noda, K; Saito, M; Starikov, E B; Tateno, M

2004-07-23

Electron-DNA anion collisions were studied using an electrostatic storage ring with a merging electron-beam technique. The rate of neutral particles emitted in collisions started to increase from definite threshold energies, which increased regularly with ion charges in steps of about 10 eV. These threshold energies were almost independent of the length and sequence of DNA, but depended strongly on the ion charges. Neutral particles came from breaks of DNAs, rather than electron detachment. The step of the threshold energy increase approximately agreed with the plasmon excitation energy. It is deduced that plasmon excitation is closely related to the reaction mechanism. Copyright 2004 The American Physical Society

Rocket effluent: Its ice nucleation activity and related properties

NASA Technical Reports Server (NTRS)

Parungo, F. P.; Allee, P. A.

1978-01-01

To investigate the possibility of inadvertent weather modification from rocket effluent, aerosol samples were collected from an instrumented aircraft subsequent to the Voyager 1 and 2 launches. The aerosol's morphology, concentration, and size distribution were examined with an electron microscope. The elemental compositions of individual particles were analyzed with an X-ray energy spectrometer. Ice nucleus concentration was measured with a thermal diffusion chamber. The particles' physical and chemical properties were related to their ice nucleation activity. A laboratory experiment on rocket propellant exhaust was conducted under controlled conditions. Both laboratory and field experimental results indicated that rocket propellant exhaust can produce active ice nuclei and modify local weather in suitable meteorological conditions.

Bounds on an energy-dependent and observer-independent speed of light from violations of locality.

PubMed

Hossenfelder, Sabine

2010-04-09

We show that models with deformations of special relativity that have an energy-dependent speed of light have nonlocal effects. The requirement that the arising nonlocality is not in conflict with known particle physics allows us to derive strong bounds on deformations of special relativity and rule out a modification to first order in energy over the Planck mass.

Particle drag history in a subcritical post-shock flow - data analysis method and uncertainty

NASA Astrophysics Data System (ADS)

Ding, Liuyang; Bordoloi, Ankur; Adrian, Ronald; Prestridge, Kathy; Arizona State University Team; Los Alamos National Laboratory Team

2017-11-01

A novel data analysis method for measuring particle drag in an 8-pulse particle tracking velocimetry-accelerometry (PTVA) experiment is described. We represented the particle drag history, CD(t) , using polynomials up to the third order. An analytical model for continuous particle position history was derived by integrating an equation relating CD(t) with particle velocity and acceleration. The coefficients of CD(t) were then calculated by fitting the position history model to eight measured particle locations in the sense of least squares. A preliminary test with experimental data showed that the new method yielded physically more reasonable particle velocity and acceleration history compared to conventionally adopted polynomial fitting. To fully assess and optimize the performance of the new method, we performed a PTVA simulation by assuming a ground truth of particle motion based on an ensemble of experimental data. The results indicated a significant reduction in the RMS error of CD. We also found that for particle locating noise between 0.1 and 3 pixels, a range encountered in our experiment, the lowest RMS error was achieved by using the quadratic CD(t) model. Furthermore, we will also discuss the optimization of the pulse timing configuration.

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.

Recent progress in the physics of microfluidics and related biotechnological applications.

PubMed

Tabeling, Patrick

2014-02-01

Since the mid-nineties, the physical understanding of microfluidic flows has reached a level sufficiently elaborate for envisaging applications in all sorts of domains. As the domain expanded, the existence of new situations where fluid dynamics at small or moderate Reynolds numbers combines with confinement, interfaces, transport, particles along with disordered substrates raised new challenges. The present review is restricted to three domains in which progress in the physical description has been made recently (droplet-based, inertial and paper-based microfluidics) and for which biotechnological applications are foreseeable. Copyright © 2013 Elsevier Ltd. All rights reserved.

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

Direct measurement of wall slip and slip layer thickness of non-Brownian hard-sphere suspensions in rectangular channel flows

NASA Astrophysics Data System (ADS)

Jesinghausen, Steffen; Weiffen, Rene; Schmid, Hans-Joachim

2016-09-01

Wall slip is a long-known phenomenon in the field of rheology. Nevertheless, the origin and the evolution are not completely clear yet. Regarding suspensions, the effect becomes even more complicated, because different mechanisms like pure slip or slip due to particle migration have to be taken into account. Furthermore, suspensions themselves show many flow anomalies and the isolation of slip is complicated. In order to develop working physical models, further insight is necessary. In this work, we measured experimentally the wall slip velocities of different highly filled suspensions in a rectangular slit die directly with respect to the particle concentration and the particle size. The slip velocities were obtained using a particle image velocimetry (PIV) system. The suspensions consisting of a castor oil-cinnamon oil blend and PMMA particles were matched in terms of refractive indexes to appear transparent. Hereby, possible optical path lengths larger than 15 mm were achieved. The slip velocities were found to be in a quadratic relation to the wall shear stress. Furthermore, the overall flow rate as well as the particle concentration has a direct influence on the slip. Concerning the shear stress, there seem to be two regions of slip with different physical characteristics. Furthermore, we estimated the slip layer thickness directly from the velocity profiles and propose a new interpretation. The PIV technique is used to investigate the viscosity and implicit the concentration profile in the slit die. It is shown that the particle migration process is quite fast.

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.

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.

Local random configuration-tree theory for string repetition and facilitated dynamics of glass

NASA Astrophysics Data System (ADS)

Lam, Chi-Hang

2018-02-01

We derive a microscopic theory of glassy dynamics based on the transport of voids by micro-string motions, each of which involves particles arranged in a line hopping simultaneously displacing one another. Disorder is modeled by a random energy landscape quenched in the configuration space of distinguishable particles, but transient in the physical space as expected for glassy fluids. We study the evolution of local regions with m coupled voids. At a low temperature, energetically accessible local particle configurations can be organized into a random tree with nodes and edges denoting configurations and micro-string propagations respectively. Such trees defined in the configuration space naturally describe systems defined in two- or three-dimensional physical space. A micro-string propagation initiated by a void can facilitate similar motions by other voids via perturbing the random energy landscape, realizing path interactions between voids or equivalently string interactions. We obtain explicit expressions of the particle diffusion coefficient and a particle return probability. Under our approximation, as temperature decreases, random trees of energetically accessible configurations exhibit a sequence of percolation transitions in the configuration space, with local regions containing fewer coupled voids entering the non-percolating immobile phase first. Dynamics is dominated by coupled voids of an optimal group size, which increases as temperature decreases. Comparison with a distinguishable-particle lattice model (DPLM) of glass shows very good quantitative agreements using only two adjustable parameters related to typical energy fluctuations and the interaction range of the micro-strings.

Characterization of the Particle Size and Polydispersity of Dicumarol Using Solid-State NMR Spectroscopy.

PubMed

Dempah, Kassibla Elodie; Lubach, Joseph W; Munson, Eric J

2017-03-06

A variety of particle sizes of a model compound, dicumarol, were prepared and characterized in order to investigate the correlation between particle size and solid-state NMR (SSNMR) proton spin-lattice relaxation ( 1 H T 1 ) times. Conventional laser diffraction and scanning electron microscopy were used as particle size measurement techniques and showed crystalline dicumarol samples with sizes ranging from tens of micrometers to a few micrometers. Dicumarol samples were prepared using both bottom-up and top-down particle size control approaches, via antisolvent microprecipitation and cryogrinding. It was observed that smaller particles of dicumarol generally had shorter 1 H T 1 times than larger ones. Additionally, cryomilled particles had the shortest 1 H T 1 times encountered (8 s). SSNMR 1 H T 1 times of all the samples were measured and showed as-received dicumarol to have a T 1 of 1500 s, whereas the 1 H T 1 times of the precipitated samples ranged from 20 to 80 s, with no apparent change in the physical form of dicumarol. Physical mixtures of different sized particles were also analyzed to determine the effect of sample inhomogeneity on 1 H T 1 values. Mixtures of cryoground and as-received dicumarol were clearly inhomogeneous as they did not fit well to a one-component relaxation model, but could be fit much better to a two-component model with both fast-and slow-relaxing regimes. Results indicate that samples of crystalline dicumarol containing two significantly different particle size populations could be deconvoluted solely based on their differences in 1 H T 1 times. Relative populations of each particle size regime could also be approximated using two-component fitting models. Using NMR theory on spin diffusion as a reference, and taking into account the presence of crystal defects, a model for the correlation between the particle size of dicumarol and its 1 H T 1 time was proposed.

Flocking ferromagnetic colloids

PubMed Central

Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S.

2017-01-01

Assemblages of microscopic colloidal particles exhibit fascinating collective motion when energized by electric or magnetic fields. The behaviors range from coherent vortical motion to phase separation and dynamic self-assembly. Although colloidal systems are relatively simple, understanding their collective response, especially under out-of-equilibrium conditions, remains elusive. We report on the emergence of flocking and global rotation in the system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms, leading to the emergence of large-scale collective motion: spontaneous symmetry breaking of the clockwise/counterclockwise particle rotation, collisional alignment of particle velocities, and random particle reorientations due to shape imperfections. We have also shown that hydrodynamic interactions between the particles do not have a qualitative effect on the collective dynamics. Our findings shed light on the onset of spatial and temporal coherence in a large class of active systems, both synthetic (colloids, swarms of robots, and biopolymers) and living (suspensions of bacteria, cell colonies, and bird flocks). PMID:28246633

Flocking ferromagnetic colloids

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

Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S.

Assemblages of microscopic colloidal particles exhibit fascinating collective motion when energized by electric or magnetic fields. The behaviors range from coherent vortical motion to phase separation and dynamic self-assembly. While colloidal systems are relatively simple, understanding their collective response, especially in out of equilibrium conditions, remains elusive. Here, we report on the emergence of flocking and global rotation in the system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms leading to the emergence of largescale collective motion: spontaneous symmetry breaking of the clock /more » counterclockwise particle rotation, collisional alignment of particle velocities, and random particle re-orientations due to shape imperfections. We have also shown that hydrodynamic interactions between the particles do not have a qualitative effect on the collective dynamics. Lastly, our findings shed light on the onset of spatial and temporal coherence in a large class of active systems, both synthetic (colloids, swarms of robots, biopolymers) and living (suspensions of bacteria, cell colonies, bird flocks).« less

Flocking ferromagnetic colloids

DOE PAGES

Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S.

2017-02-15

Assemblages of microscopic colloidal particles exhibit fascinating collective motion when energized by electric or magnetic fields. The behaviors range from coherent vortical motion to phase separation and dynamic self-assembly. While colloidal systems are relatively simple, understanding their collective response, especially in out of equilibrium conditions, remains elusive. Here, we report on the emergence of flocking and global rotation in the system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms leading to the emergence of largescale collective motion: spontaneous symmetry breaking of the clock /more » counterclockwise particle rotation, collisional alignment of particle velocities, and random particle re-orientations due to shape imperfections. We have also shown that hydrodynamic interactions between the particles do not have a qualitative effect on the collective dynamics. Lastly, our findings shed light on the onset of spatial and temporal coherence in a large class of active systems, both synthetic (colloids, swarms of robots, biopolymers) and living (suspensions of bacteria, cell colonies, bird flocks).« less

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.

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

Phenomenology of pure-gauge hidden valleys at hadron colliders

NASA Astrophysics Data System (ADS)

Juknevich, Jose E.

Expectations for new physics at the LHC have been greatly influenced by the Hierarchy problem of electroweak symmetry breaking. However, there are reasons to believe that the LHC may still discover new physics, but not directly related to the resolution of the Hierarchy problem. To ensure that such a physics does not go undiscovered requires precise understanding of how new phenomena will reveal themselves in the current and future generation of particle-physics experiments. Given this fact it seems sensible to explore other approaches to this problem; we study three alternatives here. In this thesis I argue for the plausibility that the standard model is coupled, through new massive charged or colored particles, to a hidden sector whose low energy dynamics is controlled by a pure Yang-Mills theory, with no light matter. Such a sector would have numerous metastable "hidden glueballs" built from the hidden gluons. These states would decay to particles of the standard model. I consider the phenomenology of this scenario, and find formulas for the lifetimes and branching ratios of the most important of these states. The dominant decays are to two standard model gauge bosons or to fermion-antifermion pairs, or by radiative decays with photon or Higgs emission, leading to jet- and photon-rich signals, and some occasional leptons. The presence of effective operators of different mass dimensions, often competing with each other, together with a great diversity of states, leads to a great variability in the lifetimes and decay modes of the hidden glueballs. I find that most of the operators considered in this work are not heavily constrained by precision electroweak physics, therefore leaving plenty of room in the parameter space to be explored by the future experiments at the LHC. Finally, I discuss several issues on the phenomenology of the new massive particles as well as an outlook for experimental searches.

Book review: Modern Plasma Physics, Vol. I: Physical Kinetics of Turbulent Plasmas, by Patrick H. Diamond, Sanae-I. Itoh and Kimitaka Itoh, Cambridge University Press, Cambridge (UK), 2010, IX, 417 p., ISBN 978-0-521-86920-1 (Hardback)

NASA Astrophysics Data System (ADS)

Somov, B. V.

If you want to learn not only the most fundamental things about the physics of turbulent plasmas but also the current state of the problem including the most recent results in theoretical and experimental investigations - and certainly many physicists and astrophysicists do - this series of three excellent monographs is just for you. The first volume "Physical Kinetics of Turbulent Plasmas" develops the kinetic theory of turbulence through a focus on quasi-particle models and dynamics. It discusses the concepts and theoretical methods for describing weak and strong fluid and phase space turbulence in plasma systems far from equilibrium. The core material includes fluctuation theory, self-similar cascades and transport, mean field theory, resonance broadening and nonlinear wave-particle interaction, wave-wave interaction and wave turbulence, strong turbulence theory and renormalization. The book gives readers a deep understanding of the fields under consideration and builds a foundation for future applications to multi-scale processes of self-organization in tokamaks and other confined plasmas. In spite of a short pedagogical introduction, the book is addressed mainly to well prepared readers with a serious background in plasma physics, to researchers and advanced graduate students in nonlinear plasma physics, controlled fusions and related fields such as cosmic plasma physics

Dynamics of a spherical particle in an acoustic field: A multiscale approach

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

Xie, Jin-Han, E-mail: J.H.Xie@ed.ac.uk; Vanneste, Jacques

2014-10-15

A rigid spherical particle in an acoustic wave field oscillates at the wave period but has also a mean motion on a longer time scale. The dynamics of this mean motion is crucial for numerous applications of acoustic microfluidics, including particle manipulation and flow visualisation. It is controlled by four physical effects: acoustic (radiation) pressure, streaming, inertia, and viscous drag. In this paper, we carry out a systematic multiscale analysis of the problem in order to assess the relative importance of these effects depending on the parameters of the system that include wave amplitude, wavelength, sound speed, sphere radius, andmore » viscosity. We identify two distinguished regimes characterised by a balance among three of the four effects, and we derive the equations that govern the mean particle motion in each regime. This recovers and organises classical results by King [“On the acoustic radiation pressure on spheres,” Proc. R. Soc. A 147, 212–240 (1934)], Gor'kov [“On the forces acting on a small particle in an acoustical field in an ideal fluid,” Sov. Phys. 6, 773–775 (1962)], and Doinikov [“Acoustic radiation pressure on a rigid sphere in a viscous fluid,” Proc. R. Soc. London A 447, 447–466 (1994)], clarifies the range of validity of these results, and reveals a new nonlinear dynamical regime. In this regime, the mean motion of the particle remains intimately coupled to that of the surrounding fluid, and while viscosity affects the fluid motion, it plays no part in the acoustic pressure. Simplified equations, valid when only two physical effects control the particle motion, are also derived. They are used to obtain sufficient conditions for the particle to behave as a passive tracer of the Lagrangian-mean fluid motion.« less

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.

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.

Einstein’s Clocks

ScienceCinema

Lincoln, Don

2018-01-16

One of the most non-intuitive physics theories ever devised is Einstein’s Theory of Special Relativity, which claim such crazy-sounding things as two people disagreeing on such familiar concepts as length and time. In this video, Fermilab’s Dr. Don Lincoln shows that every single day particle physicists prove that moving clocks tick more slowly than stationary ones. He uses an easy to understand example of particles that move for far longer distances than you would expect from combining their velocity and stationary lifetime.

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

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…

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

Physics Division progress report, January 1, 1984-September 30, 1986

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

Keller, W.E.

1987-10-01

This report provides brief accounts of significant progress in development activities and research results achieved by Physics Division personnel during the period January 1, 1984, through September 31, 1986. These efforts are representative of the three main areas of experimental research and development in which the Physics Division serves Los Alamos National Laboratory's and the Nation's needs in defense and basic sciences: (1) defense physics, including the development of diagnostic methods for weapons tests, weapon-related high-energy-density physics, and programs supporting the Strategic Defense Initiative; (2) laser physics and applications, especially to high-density plasmas; and (3) fundamental research in nuclear andmore » particle physics, condensed-matter physics, and biophysics. Throughout the report, emphasis is placed on the design, construction, and application of a variety of advanced, often unique, instruments and instrument systems that maintain the Division's position at the leading edge of research and development in the specific fields germane to its mission. A sampling of experimental systems of particular interest would include the relativistic electron-beam accelerator and its applications to high-energy-density plasmas; pulsed-power facilities; directed energy weapon devices such as free-electron lasers and neutral-particle-beam accelerators; high-intensity ultraviolet and x-ray beam lines at the National Synchrotron Light Source (at Brookhaven National Laboratory); the Aurora KrF ultraviolet laser system for projected use as an inertial fusion driver; antiproton physics facility at CERN; and several beam developments at the Los Alamos Meson Physics Facility for studying nuclear, condensed-matter, and biological physics, highlighted by progress in establishing the Los Alamos Neutron Scattering Center.« less

Measurement of limiter particle fluxes and carbon erosion in the helical scrape-off layer of startup plasmas at W7-X

NASA Astrophysics Data System (ADS)

Winters, V.; Biedermann, C.; Brezinsek, S.; Effenberg, F.; Frerichs, H.; Harris, J.; Schmitz, O.; Stephey, L.; Unterberg, E.; Wurden, G.; W7-X Team

2016-10-01

Measurement of the 2D recycling flux and calculations of the carbon erosion from the limiter in startup plasmas of W7-X provides a first insight into neutral particle release and impurity inflow into the helical scrape-off layer. H-alpha, C-II (514.5nm) and C-III (465.1nm) line emissions were collected with filter-scopes and a visible camera aimed at limiter 3 of W7-X. Local plasma parameters are considered to estimate physical and chemical sputtering contributions. The analytical model for chemical sputtering by Roth is used to convert the measured particle flux into a chemically eroded C flux. The particle flux as well as the extracted C erosion pattern deviates from the measured heat flux distribution and also from the predicted particle flux distribution from EMC3-EIRENE. Candidates to resolve this discrepancy are measurement uncertainties and physics related (e.g. asymmetry in the last closed flux surface position). Post-mortem analysis of the limiter will be taken into account and compared to these in-situ measurements to gather first detailed insight on the net C erosion distribution and the impurity sourcing into the helical scrape-off layer. This work was funded by DE-SC0014210, DE-AC5206NA25396, DE-AC05-00OR22725 and by EUROfusion under Grant No 633053.

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.

Structure and Dynamics of Interacting Nanoparticles in Semidilute Polymer Solutions

DOE PAGES

Pollng-Skutvik, Ryan; Mongcopa, Katrina Irene S.; Faraone, Antonio; ...

2016-08-17

We investigate the structure and dynamics of silica nanoparticles and polymer chains in semidilute solutions of high molecular weight polystyrene in 2-butanone to determine the effect of long-range interparticle interactions on the coupling between particle and polymer dynamics. Particles at concentrations of 1–10 wt % are well dispersed in the semidilute polymer solutions and exhibit long-range electrostatic repulsions between particles. Because the particles are comparably sized to the radius of gyration of the polymer, the particle dynamics is predicted to couple to that of the polymer. We verify that the polymer structure and dynamics are not significantly affected by themore » particles, indicating that the particle–polymer coupling does not change with increasing particle loading. We find that the coupling between the dynamics of comparably sized particles and polymer results in subdiffusive particle dynamics, as expected. Over the interparticle distance, however, the particle dynamics is hindered and not fully described by the relaxation of the surrounding polymer chains. Instead, the particle dynamics is inversely related to the structure factor, suggesting that physical particle–polymer coupling on short length scales and interparticle interactions on long length scales both present energetic barriers to particle motion that lead to subdiffusive dynamics and de Gennes narrowing, respectively.« less

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.

The legacy of uncertainty

NASA Technical Reports Server (NTRS)

Brown, Laurie M.

1993-01-01

An historical account is given of the circumstances whereby the uncertainty relations were introduced into physics by Heisenberg. The criticisms of QED on measurement-theoretical grounds by Landau and Peierls are then discussed, as well as the response to them by Bohr and Rosenfeld. Finally, some examples are given of how the new freedom to advance radical proposals, in part the result of the revolution brought about by 'uncertainty,' was implemented in dealing with the new phenomena encountered in elementary particle physics in the 1930's.

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine

PubMed Central

2012-01-01

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered. PMID:22348683

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.

Analysis of the physical properties of black carbon coatings from near-road to remote aging scales

NASA Astrophysics Data System (ADS)

Krasowsky, T. S.; McMeeking, G. R.; Sioutas, C.; Ban-Weiss, G. A.

2017-12-01

As black carbon (BC) particles are transported in the atmosphere, they acquire soluble coatings with important environmental implications. However, there is still vast uncertainty associated with "how" and "when" coatings accumulate on BC particles, including at rapid time-scales (e.g., adjacent to major roadways) and at more remote locations. A Single-Particle Soot Photometer (SP2) was used to measure refractory BC during the summer months in Los Angeles, California. BC physical properties were compared near a major freeway and at a remote receptor site in Redlands, California, approximately 100 km east of the downtown Los Angeles area. We have attempted to reduce uncertainty associated with the mechanisms that govern the procurement of soluble coatings on BC by investigating various meteorological regimes and comparing weekday to weekend BC properties. BC coatings were quantified using the "Lag-Time" and "Leading-Edge-Only" methods. Results reported here show an increased fraction of thickly-coated BC particles up to 115 meters from the roadway where competing partial pressure and vapor pressure causes various species to condense on BC as distance from the roadway increases. However, the median coating thickness for all BC particles measured near the roadway on August 4, 2016 was approximately 0 nm indicating BC particles near major roads are mostly uncoated. Despite ever-changing meteorological regimes at the receptor site, BC at the receptor site exhibited remarkably similar properties to BC measured 115 meters from the roadway. Although the overall mixing states were not vastly different at the roadway source and receptor sites, there were systematic mixing state dependencies based on changes in meteorological regimes and the day of week measured. On weekends, a higher relative portion of gasoline vehicles than diesel trucks may be leading to relatively more secondary organic aerosols to coat proportionately less BC mass.

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.

The properties and behavior of α-pinene secondary organic aerosol particles exposed to ammonia under dry conditions

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

Bell, David M.; Imre, Dan; T. Martin, Scot

Chemical transformations and aging of secondary organic aerosol (SOA) particles can alter their physical and chemical properties, including particle morphology. Ammonia, one of the common atmospheric reactive constituents, can react with SOA particles, changing their properties and behavior. At low relative humidity NH3 uptake by α-pinene SOA particles appears to be limited to the particle surface, which suggests that the reacted particles might not be homogeneous and have complex morphology. Here, we present a study aimed at detailed characterization of the effect of ammonia on the composition, density, morphology, shape, and evaporation kinetics of α-pinene SOA particles. We find thatmore » a small amount of NH3 diffuses and reacts throughout the particles bulk, while most of the ammoniated products result from the reaction of NH3 with carboxylic acids on the particle surface, leading to a slight increase in particle size. We show that the reaction products form a solid semi-volatile coating that is a few nanometers thick. This solid coating prevents coagulating particles from coalescing for over two days. However, when the gas phase is diluted this semi-volatile coating evaporates in minutes, which is ensued by rapid coalescence. The ammoniated products in the particle bulk affect particles evaporation kinetics, more so for the smaller particles that contain higher fraction of ammoniated products.« less

Statistical theory on the analytical form of cloud particle size distributions

NASA Astrophysics Data System (ADS)

Wu, Wei; McFarquhar, Greg

2017-11-01

Several analytical forms of cloud particle size distributions (PSDs) have been used in numerical modeling and remote sensing retrieval studies of clouds and precipitation, including exponential, gamma, lognormal, and Weibull distributions. However, there is no satisfying physical explanation as to why certain distribution forms preferentially occur instead of others. Theoretically, the analytical form of a PSD can be derived by directly solving the general dynamic equation, but no analytical solutions have been found yet. Instead of using a process level approach, the use of the principle of maximum entropy (MaxEnt) for determining the analytical form of PSDs from the perspective of system is examined here. Here, the issue of variability under coordinate transformations that arises using the Gibbs/Shannon definition of entropy is identified, and the use of the concept of relative entropy to avoid these problems is discussed. Focusing on cloud physics, the four-parameter generalized gamma distribution is proposed as the analytical form of a PSD using the principle of maximum (relative) entropy with assumptions on power law relations between state variables, scale invariance and a further constraint on the expectation of one state variable (e.g. bulk water mass). DOE ASR.

Silage review: Silage feeding management: Silage characteristics and dairy cow feeding behavior.

PubMed

Grant, R J; Ferraretto, L F

2018-05-01

Feeding environment and feed accessibility influence the dairy cow's response to the ration and forage composition. Fiber content, physical form, and fermentability influence feeding behavior, feed intake, and overall cow metabolic and lactational responses to forage. It is possible to vary eating time of lactating dairy cattle by over 1 h/d by changing dietary silage fiber content, digestibility, and particle size. Optimizing silage particle size is important because excessively long particles increase the necessary chewing to swallow a bolus of feed, thereby increasing eating time. Under competitive feeding situations, excessively coarse or lower fiber digestibility silages may limit DMI of lactating dairy cows due to eating time requirements that exceed available time at the feed bunk. Additionally, greater silage particle size, especially the particles retained on the 19-mm sieve using the Penn State Particle Separator, are most likely to be sorted. Silage starch content and fermentability may influence ruminal propionate production and thereby exert substantial control over meal patterns and feed consumption. Compared with silage fiber characteristics, relatively little research has assessed how silage starch content and fermentability interact with the feeding environment to influence dairy cow feeding behavior. Finally, voluminous literature exists on the potential effects that silage fermentation end products have on feeding behavior and feed intake. However, the specific mechanisms of how these end products influence behavior and intake are poorly understood in some cases. The compounds shown to have the greatest effect on feeding behavior are lactate, acetate, propionate, butyrate, ammonia-N, and amines. Any limitation in the feeding environment will likely accentuate the negative response to poor silage fermentation. In the future, to optimize feeding behavior and dry matter intake of silage-based diets fed to dairy cattle, we will need to consider the chemical and physical properties of silage, end products of silage fermentation, and the social and physical components of the feeding environment. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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).

Relation between leaching characteristics of heavy metals and physical properties of fly ashes from typical municipal solid waste incinerators.

PubMed

Ni, Peng; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

2017-09-01

Due to the alkalinity and high concentration of potentially hazardous heavy metals, fly ash from a municipal solid waste (MSW) incinerator is classified as hazardous waste, which should be of particular concern. Physical and chemical characterizations of the contrasted fly ashes were investigated to explore the relation between leaching characteristics of heavy metals and physical properties of fly ashes. The results showed that CaClOH, NaCl, Ca(OH) 2 , KCl and SiO 2 were primary mineral compositions in the MSWI fly ashes, and the particle size distribution of fly ash ranged between 10 μm and 300 μm. The smaller the particle size distribution of fly ash, the larger the BET-specific surface area, which was beneficial to the leaching of heavy metals. As a result of various pores, it easily accumulated heavy metals as well. The leaching tests exhibited a high leachability of heavy metals and the leaching concentration of Pb in almost all of the fly ash samples went far beyond the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Thereupon, it is necessary to establish proper disposal systems and management strategies for environmental protection based on the characteristics of MSW incineration (MSWI) fly ash in China.

Study of erosion characterization of carbon fiber reinforced composite material

NASA Astrophysics Data System (ADS)

Debnath, Uttam Kumar; Chowdhury, Mohammad Asaduzzaman; Kowser, Md. Arefin; Mia, Md. Shahin

2017-06-01

Carbon fiber composite materials are widely used at different engineering and industrial applications there are good physical, mechanical, chemical properties and light weight. Erosion behavior of materials depends on various factors such as impact angle, particle velocity, particle size, particle shape, particle type, particle flux, temperature of the tested materials. Among these factors impact angle and particle velocity have been recognized as two parameters that noticeably influence the erosion rates of all tested materials. Irregular shaped sand (SiO2) particles of various sizes (200-300 µm, 400-500 µm, and 500-600 µm) were selected erosive element. Tested conditions such as impingement angles between 15 degree to 90 degree, impact velocities between 30-50 m/sec, and stand-off distances 15-25 mm at surrounding room temperature were maintained. The highest level of erosion of the tested composite is obtained at 60° impact angle, which signifies the semi-ductile behavior of this material. Erosion showed increasing trend with impact velocity and decreasing nature in relation to stand-off distance. Surface damage was analyzed using SEM to examine the nature of the erosive wear mechanism.

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.

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.

Very special conformal field theories and their holographic duals

NASA Astrophysics Data System (ADS)

Nakayama, Yu

2018-03-01

Cohen and Glashow introduced the notion of very special relativity as viable space-time symmetry of elementary particle physics. As a natural generalization of their idea, we study the subgroup of the conformal group, dubbed very special conformal symmetry, which is an extension of the very special relativity. We classify all of them and construct field theory examples as well as holographic realization of the very special conformal field theories.

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.

Tests and prospects of new physics at very high energy. Beyond the standard basic principles, and beyond conventional matter and space-time. On the possible origin of Quantum Mechanics.

NASA Astrophysics Data System (ADS)

Gonzalez-Mestres, Luis

2015-05-01

Recent results and announcements by Planck and BICEP2 have led to important controversies in the fields of Cosmology and Particle Physics. As new ideas and alternative approaches can since then more easily emerge, the link between the Mathematical Physics aspects of theories and the interpretation of experimental results becomes more direct. This evolution is also relevant for Particle Physics experiments at very high energy, where the interpretation of data on the highest-energy cosmic rays remains a major theoretical and phenomenological challenge. Alternative particle physics and cosmology can raise fundamental questions such as that of the structure of vacuum and space-time. In particular, the simplified description of the physical vacuum contained in standard quantum field theory does not necessarily correspond to reality at a deeper level, and similarly for the relativistic space-time based on four real variables. In a more general approach, the definition itself of vacuum can be a difficult task. The spinorial space-time (SST) we suggested in 1996-97 automatically incorporates a local privileged space direction (PSD) for each comoving observer, possibly leading to a locally anisotropic vacuum structure. As the existence of the PSD may have been confirmed by Planck, and a possible discovery of primordial B-modes in the polarization of the cosmic microwave background radiation (CMB) may turn out to contain new evidence for the SST, we explore other possible implications of this approach to space-time. The SST structure can naturally be at the origin of Quantum Mechanics at distance scales larger than the fundamental one if standard particles are dealt with as vacuum excitations. We also discuss possible implications of our lack of knowledge of the structure of vacuum, as well as related theoretical, phenomenological and cosmological uncertainties. Pre-Big Bang scenarios and new ultimate constituents of matter (including superbradyons) are crucial open subjects, together with vacuum structure and the interaction between vacuum and standard matter.

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

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

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.

Evidence-Based Nanoscopic and Molecular Framework for Excipient Functionality in Compressed Orally Disintegrating Tablets

PubMed Central

Al-khattawi, Ali; Alyami, Hamad; Townsend, Bill; Ma, Xianghong; Mohammed, Afzal R.

2014-01-01

The work investigates the adhesive/cohesive molecular and physical interactions together with nanoscopic features of commonly used orally disintegrating tablet (ODT) excipients microcrystalline cellulose (MCC) and D-mannitol. This helps to elucidate the underlying physico-chemical and mechanical mechanisms responsible for powder densification and optimum product functionality. Atomic force microscopy (AFM) contact mode analysis was performed to measure nano-adhesion forces and surface energies between excipient-drug particles (6-10 different particles per each pair). Moreover, surface topography images (100 nm2–10 µm2) and roughness data were acquired from AFM tapping mode. AFM data were related to ODT macro/microscopic properties obtained from SEM, FTIR, XRD, thermal analysis using DSC and TGA, disintegration testing, Heckel and tabletability profiles. The study results showed a good association between the adhesive molecular and physical forces of paired particles and the resultant densification mechanisms responsible for mechanical strength of tablets. MCC micro roughness was 3 times that of D-mannitol which explains the high hardness of MCC ODTs due to mechanical interlocking. Hydrogen bonding between MCC particles could not be established from both AFM and FTIR solid state investigation. On the contrary, D-mannitol produced fragile ODTs due to fragmentation of surface crystallites during compression attained from its weak crystal structure. Furthermore, AFM analysis has shown the presence of extensive micro fibril structures inhabiting nano pores which further supports the use of MCC as a disintegrant. Overall, excipients (and model drugs) showed mechanistic behaviour on the nano/micro scale that could be related to the functionality of materials on the macro scale. PMID:25025427

DEM Solutions Develops Answers to Modeling Lunar Dust and Regolith

NASA Technical Reports Server (NTRS)

Dunn, Carol Anne; Calle, Carlos; LaRoche, Richard D.

2010-01-01

With the proposed return to the Moon, scientists like NASA-KSC's Dr. Calle are concerned for a number of reasons. We will be staying longer on the planet's surface, future missions may include dust-raising activities, such as excavation and handling of lunar soil and rock, and we will be sending robotic instruments to do much of the work for us. Understanding more about the chemical and physical properties of lunar dust, how dust particles interact with each other and with equipment surfaces and the role of static electricity build-up on dust particles in the low-humidity lunar environment is imperative to the development of technologies for removing and preventing dust accumulation, and successfully handling lunar regolith. Dr. Calle is currently working on the problems of the electrostatic phenomena of granular and bulk materials as they apply to planetary surfaces, particularly to those of Mars and the Moon, and is heavily involved in developing instrumentation for future planetary missions. With this end in view, the NASA Kennedy Space Center's Innovative Partnerships Program Office partnered with OEM Solutions, Inc. OEM Solutions is a global leader in particle dynamics simulation software, providing custom solutions for use in tackling tough design and process problems related to bulk solids handling. Customers in industries such as pharmaceutical, chemical, mineral, and materials processing as well as oil and gas production, agricultural and construction, and geo-technical engineering use OEM Solutions' EDEM(TradeMark) software to improve the design and operation of their equipment while reducing development costs, time-to-market and operational risk. EDEM is the world's first general-purpose computer-aided engineering (CAE) tool to use state-of-the-art discrete element modeling technology for the simulation and analysis of particle handling and manufacturing operations. With EDEM you'can quickly and easily create a parameterized model of your granular solids system. Computer-aided design (CAD) models of real particles can be imported to obtain an accurate representation of their shape. EDEM(TradeMark) uses particle-scale behavior models to simulate bulk solids behavior. In addition to particle size and shape, the models can account for physical properties of particles along with interaction between particles and with equipment surfaces and surrounding media, as needed to define the physics of a particular process.

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.

Effect of photochemical aging on the ice nucleation properties of diesel and wood burning particles

NASA Astrophysics Data System (ADS)

Chou, C.; Stetzer, O.; Tritscher, T.; Chirico, R.; Heringa, M. F.; Kanji, Z. A.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.; Lohmann, U.

2012-06-01

A measurement campaign (IMBALANCE) was conducted in 2009 and aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro with no emission after-treatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, -30 °C, -35 °C and -40 °C. Freshly emitted diesel particles showed ice formation only at -40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical aging did not play a role in modifying their ice nucleation behavior. Only one diesel experiment where α-pinene was added, showed an ice nucleation enhancement after the aging at -35 °C. Wood burning particles also act as ice nuclei (IN) at -40 °C in the deposition mode at the same conditions as for diesel particles and photochemical aging did also not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at -35 °C with no ice nucleation observed at -30 °C for wood burning particles. Photochemical aging did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below -30 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical aging on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

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.

On relativistic motion of a pair of particles having opposite signs of masses

NASA Astrophysics Data System (ADS)

Ivanov, Pavel B.

2012-12-01

In this methodological note, we consider, in a weak-fleld limit, the relativistic linear motion of two particles with masses of opposite signs and a small difference between their absolute values: m_{1,2}=+/- (\\mu+/- \\Delta \\mu) , \\mu \\gt 0, \\vert\\Delta \\mu \\vert \\ll\\mu. In 1957, H Bondi showed in the framework of both Newtonian analysis and General Relativity that, when the relative motion of particles is absent, such a pair can be accelerated indefinitely. We generalize the results of his paper to account for the small nonzero difference between the velocities of the particles. Assuming that the weak-field limit holds and the dynamical system is conservative, an elementary treatment of the problem based on the laws of energy and momentum conservation shows that the system can be accelerated indefinitely, or attain very large asymptotic values of the Lorentz factor \\gamma. The system experiences indefinite acceleration when its energy-momentum vector is null and the mass difference \\Delta \\mu \\le 0. When the modulus of the square of the norm of the energy-momentum vector, \\vert N^{\\,2}\\vert, is sufficiently small, the system can be accelerated to very large \\gamma \\propto \\vert N^{\\,2}\\vert^{-1}. It is stressed that, when only leading terms in the ratio of a characteristic gravitational radius to the distance between the particles are retained, our elementary analysis leads to equations of motion equivalent to those derived from relativistic weak-field equations of motion by Havas and Goldberg in 1962. Thus, in the weak-field approximation it is possible to bring the system to the state with extremely high values of \\gamma. The positive energy carried by the particle with positive mass may be conveyed to other physical bodies, say by intercepting this particle with a target. If we suppose that there is a process of production of such pairs and the particles with positive mass are intercepted, while the negative mass particles are expelled from the region of space occupied by the physical bodies of interest, this scheme could provide a persistent transfer of positive energy to the bodies, which may be classified as `perpetual motion of the third kind'. Additionally, we critically evaluate some recent claims regarding the problem.

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

Particle Number Conserving Approach to the Collective States in a Small Fermi-System

NASA Astrophysics Data System (ADS)

Glick, Jennifer; Zelevinsky, Vladimir

2014-03-01

The standard Bardeen-Cooper-Schrieffer (BCS) description of pairing theory, random phase approximation (RPA) and Hartree-Fock-Bogoliubov (HFB) methods, routinely used in macroscopic many-body physics when the dimension of the Hamiltonian matrix is prohibitively large, include features which are not well suited to describe mesoscopic systems such as nuclei or cold atoms in traps. Two important disadvantages are the non-conservation of exact particle number through the introduction of quasiparticles, and the absence of a non-trivial paired solution in the discrete spectrum with weak pairing. We develop the pairing theory based on the exact particle number conservation, whose first applications to the ground state physics presented in [A. Volya and V. Zelevinsky, in 50 Years of Nuclear BCS, World Scientific, 2012] demonstrated that such an approach avoids well known deficiencies of the standard treatment, especially in the region of weak pairing. Now, we use the method for low-lying collective excitations which in many cases are even more sensitive to conservation laws. We show that the RPA version based on solving the operator equations of motion is reduced to the set of recurrence relations for neighboring systems which precisely conserve the exact particle number. Supported by the NSF grant PHY-1068217.

A fresh look at crater scaling laws for normal and oblique hypervelocity impacts

NASA Technical Reports Server (NTRS)

Watts, A. J.; Atkinson, D. R.; Rieco, S. R.; Brandvold, J. B.; Lapin, S. L.; Coombs, C. R.

1993-01-01

With the concomitant increase in the amount of man-made debris and an ever increasing use of space satellites, the issue of accidental collisions with particles becomes more severe. While the natural micrometeoroid population is unavoidable and assumed constant, continued launches increase the debris population at a steady rate. Debris currently includes items ranging in size from microns to meters which originated from spent satellites and rocket cases. To understand and model these environments, impact damage in the form of craters and perforations must be analyzed. Returned spacecraft materials such as those from LDEF and Solar Max have provided such a testbed. From these space-aged samples various impact parameters (i.e., particle size, particle and target material, particle shape, relative impact speed, etc.) may be determined. These types of analyses require the use of generic analytic scaling laws which can adequately describe the impact effects. Currently, most existing analytic scaling laws are little more than curve-fits to limited data and are not based on physics, and thus are not generically applicable over a wide range of impact parameters. During this study, a series of physics-based scaling laws for normal and oblique crater and perforation formation has been generated into two types of materials: aluminum and Teflon.

Flow properties and chemical composition of carob (Ceratonia siliqua L.) flours as related to particle size and seed presence.

PubMed

Benković, Maja; Belščak-Cvitanović, Ana; Bauman, Ingrid; Komes, Draženka; Srečec, Siniša

2017-10-01

Due to abundance in carbohydrates, dietary fibres and bioactive compounds, as well as for its outspread and low prices, carob (Ceratonia siliqua L.) flour has a great potential of use as a functional ingredient. The aim of this study was to analyse this potential by physical and chemical properties assessment of different particle sizes of carob flour with and without seeds. The influence of seed presence on physical and chemical properties of flour was also investigated. Seed presence in carob flour led to higher cohesivity and cake strength. It also affected the extraction efficiency of polyphenols, which was confirmed by the ranking of samples according to their procyanidin and tannins contents. With regard to the carbohydrate content, significant differences (P<0.05) between the contents of fructose and glucose was established in samples differing by the presence of carob seeds. Spearman rank order correlations revealed a significant difference (P<0.05) between physical and chemical properties of carob flours. These findings confirm the importance of understanding physical and chemical properties of carob flours in order to use them efficiently as a functional food ingredient. Copyright © 2017 Elsevier Ltd. All rights reserved.

General Relativistic Smoothed Particle Hydrodynamics code developments: A progress report

NASA Astrophysics Data System (ADS)

Faber, Joshua; Silberman, Zachary; Rizzo, Monica

2017-01-01

We report on our progress in developing a new general relativistic Smoothed Particle Hydrodynamics (SPH) code, which will be appropriate for studying the properties of accretion disks around black holes as well as compact object binary mergers and their ejecta. We will discuss in turn the relativistic formalisms being used to handle the evolution, our techniques for dealing with conservative and primitive variables, as well as those used to ensure proper conservation of various physical quantities. Code tests and performance metrics will be discussed, as will the prospects for including smoothed particle hydrodynamics codes within other numerical relativity codebases, particularly the publicly available Einstein Toolkit. We acknowledge support from NSF award ACI-1550436 and an internal RIT D-RIG grant.

Adhesion of Lunar Dust

NASA Astrophysics Data System (ADS)

Walton, Otis R.

2007-04-01

This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

Comment on ;Acceleration of particles to high energy via gravitational repulsion in the Schwarzschild field; [Astropart. Phys. 86 (2017) 18-20

NASA Astrophysics Data System (ADS)

Spallicci, Alessandro D. A. M.

2017-09-01

Comments are due on a recent paper by McGruder III (2017) in which the author deals with the concept of gravitational repulsion in the context of the Schwarzschild-Droste solution. Repulsion (deceleration) for ingoing particles into a black hole is a concept proposed several times starting from Droste himself in 1916. It is a coordinate effect appearing to an observer at a remote distance from the black hole and when coordinate time is employed. Repulsion has no bearing and relation to the local physics of the black hole, and moreover it cannot be held responsible for accelerating outgoing particles. Thereby, the energy boost of cosmic rays cannot be produced by repulsion.

Adhesion of Lunar Dust

NASA Technical Reports Server (NTRS)

Walton, Otis R.

2007-01-01

This paper reviews the physical characteristics of lunar dust and the effects of various fundamental forces acting on dust particles on surfaces in a lunar environment. There are transport forces and adhesion forces after contact. Mechanical forces (i.e., from rover wheels, astronaut boots and rocket engine blast) and static electric effects (from UV photo-ionization and/or tribo-electric charging) are likely to be the major contributors to the transport of dust particles. If fine regolith particles are deposited on a surface, then surface energy-related (e.g., van der Walls) adhesion forces and static-electric-image forces are likely to be the strongest contributors to adhesion. Some measurement techniques are offered to quantify the strength of adhesion forces. And finally some dust removal techniques are discussed.

Neutrinos as Probes of Lorentz Invariance

DOE PAGES

Díaz, Jorge S.

2014-01-01

Neutrinos can be used to search for deviations from exact Lorentz invariance. The worldwide experimental program in neutrino physics makes these particles a remarkable tool to search for a variety of signals that could reveal minute relativity violations. This paper reviews the generic experimental signatures of the breakdown of Lorentz symmetry in the neutrino sector.

Suggestions for Evaluating the Quality of the Army’s Science and Technology Program: The Portfolio and Its Execution

DTIC Science & Technology

2013-01-01

definition of 6.1 research apply. Namely, the work is curiosity work with no specific application in mind. The two extramural categories include...direct interest in relativity and gravitation, cosmology , elementary particles, nuclear physics, astronomy, or astrophysics, since they generally have

Improving Metallic Thermal Protection System Hypervelocity Impact Resistance Through Design of Experiments Approach

NASA Technical Reports Server (NTRS)

Poteet, Carl C.; Blosser, Max L.

2001-01-01

A design of experiments approach has been implemented using computational hypervelocity impact simulations to determine the most effective place to add mass to an existing metallic Thermal Protection System (TPS) to improve hypervelocity impact protection. Simulations were performed using axisymmetric models in CTH, a shock-physics code developed by Sandia National Laboratories, and validated by comparison with existing test data. The axisymmetric models were then used in a statistical sensitivity analysis to determine the influence of five design parameters on degree of hypervelocity particle dispersion. Several damage metrics were identified and evaluated. Damage metrics related to the extent of substructure damage were seen to produce misleading results, however damage metrics related to the degree of dispersion of the hypervelocity particle produced results that corresponded to physical intuition. Based on analysis of variance results it was concluded that the most effective way to increase hypervelocity impact resistance is to increase the thickness of the outer foil layer. Increasing the spacing between the outer surface and the substructure is also very effective at increasing dispersion.

Results of heavy ion radiotherapy

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

Castro, J.R.

1994-04-01

The potential of heavy ion therapy for clinical use in cancer therapy stems from the biological parameters of heavy charged particles, and their precise dose localization. Biologically, carbon, neon and other heavy ion beams (up to about silicon) are clinically useful in overcoming the radioresistance of hypoxic tumors, thus increasing biological effectiveness relative to low-LET x-ray or electron beams. Cells irradiated by heavy ions show less variation in cell-cycle related radiosensitivity and decreased repair of radiation injury. The physical parameters of these heavy charged particles allow precise delivery of high radiation doses to tumors while minimizing irradiation of normal tissues.more » Clinical use requires close interaction between radiation oncologists, medical physicists, accelerator physicists, engineers, computer scientists and radiation biologists.« less

Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

DOEpatents

Harris, M.T.; Basaran, O.A.; Sisson, W.G.; Brunson, R.R.

1997-02-18

The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity. 3 figs.

Estimation of the R134a gas refractive index for use as a Cherenkov radiator, using a high energy charged particle beam

NASA Astrophysics Data System (ADS)

Charitonidis, N.; Karyotakis, Y.; Gatignon, L.

2017-11-01

Gases with relatively high refractive index, n - 1 ≥ 500 ×10-6 at atmospheric pressure, giving a satisfactory photoelectron yield at relatively low pressures (≤ 5 bar) are rare. These gases are often the only practical solution for low momentum particle identification in conventional secondary beam lines. The refractive index of R134a, one of the most common gases available to the physics community, has never been measured or reported. In the present note, the results of a dedicated experiment to estimate the refractive index of R134a, using mixed hadron/electron beams in the range 0.5-10 GeV are presented.

Particle transport and deposition: basic physics of particle kinetics.

PubMed

Tsuda, Akira; Henry, Frank S; Butler, James P

2013-10-01

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. The particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic. Conversely, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drugs. 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 article. A large portion of this article deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: (i) the physical characteristics of particles, (ii) particle behavior in gas flow, and (iii) 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 article concludes with a summary and a brief discussion of areas of future research. © 2013 American Physiological Society. Compr Physiol 3:1437-1471, 2013.

A pedagogical derivation of the matrix element method in particle physics data analysis

NASA Astrophysics Data System (ADS)

Sumowidagdo, Suharyo

2018-03-01

The matrix element method provides a direct connection between the underlying theory of particle physics processes and detector-level physical observables. I am presenting a pedagogically-oriented derivation of the matrix element method, drawing from elementary concepts in probability theory, statistics, and the process of experimental measurements. The level of treatment should be suitable for beginning research student in phenomenology and experimental high energy physics.

Instrumentation for Applied Physics and Industrial Applications

NASA Astrophysics Data System (ADS)

Hillemanns, H.; Le Goff, J.-M.

This document is part of Part 2 'Principles and Methods' of Subvolume B 'Detectors for Particles and Radiation' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Section '7.3 Instrumentation for Applied Physics and Industrial Applications' of Chapter '7 Applications of Detectors in Technology; Medicine and Other Fields' with the content:

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

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

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.

Design evaluations for a flight cloud physics holocamera. [holographic/photographic camera for low-g Atmospheric Cloud Physics Laboratory

NASA Technical Reports Server (NTRS)

Moore, W. W., Jr.; Kurtz, R. L.; Lemons, J. F.

1976-01-01

The paper describes a holographic/photographic camera to be used with the zero-g or low-g Atmospheric Cloud Physics Laboratory. The flight prototype holocamera is intended to record particles from 0.01 to 5 microns for an optimum two-dimensional plane only in the microscopic photography mode, particles on a volume basis in the in-line holography mode from 5 microns up, and all particle sizes possible on a volume basis in the acute sideband holography mode.

Reduction in biomass burning aerosol light absorption upon humidification: roles of inorganically-induced hygroscopicity, particle collapse, and photoacoustic heat and mass transfer

NASA Astrophysics Data System (ADS)

Lewis, K. A.; Arnott, W. P.; Moosmüller, H.; Chakrabarty, R. K.; Carrico, C. M.; Kreidenweis, S. M.; Day, D. E.; Malm, W. C.; Laskin, A.; Jimenez, J. L.; Ulbrich, I. M.; Huffman, J. A.; Onasch, T. B.; Trimborn, A.; Liu, L.; Mishchenko, M. I.

2009-07-01

Smoke particle emissions from the combustion of biomass fuels typical for the western and southeastern United States were studied and compared under high humidity and ambient conditions in the laboratory. The fuels used are Montana ponderosa pine (Pinus ponderosa), southern California chamise (Adenostoma fasciculatum), and Florida saw palmetto (Serenoa repens). Information on the non-refractory chemical composition of biomass burning aerosol from each fuel was obtained with an aerosol mass spectrometer and through estimation of the black carbon concentration from light absorption measurements at 870 nm. Changes in the optical and physical particle properties under high humidity conditions were observed for hygroscopic smoke particles containing substantial inorganic mass fractions that were emitted from combustion of chamise and palmetto fuels. Light scattering cross sections increased under high humidity for these particles, consistent with the hygroscopic growth measured for 100 nm particles in HTDMA measurements. Photoacoustic measurements of aerosol light absorption coefficients reveal a 20% reduction with increasing relative humidity, contrary to the expectation of light absorption enhancement by the liquid coating taken up by hygroscopic particles. This reduction is hypothesized to arise from two mechanisms: 1. Shielding of inner monomers after particle consolidation or collapse with water uptake; 2. The contribution of mass transfer through evaporation and condensation at high relative humidity to the usual heat transfer pathway for energy release by laser-heated particles in the photoacoustic measurement of aerosol light absorption. The mass transfer contribution is used to evaluate the fraction of aerosol surface covered with liquid water solution as a function of RH.

In situ real-time measurement of physical characteristics of airborne bacterial particles

NASA Astrophysics Data System (ADS)

Jung, Jae Hee; Lee, Jung Eun

2013-12-01

Bioaerosols, including aerosolized bacteria, viruses, and fungi, are associated with public health and environmental problems. One promising control method to reduce the harmful effects of bioaerosols is thermal inactivation via a continuous-flow high-temperature short-time (HTST) system. However, variations in bioaerosol physical characteristics - for example, the particle size and shape - during the continuous-flow inactivation process can change the transport properties in the air, which can affect particle deposition in the human respiratory system or the filtration efficiency of ventilation systems. Real-time particle monitoring techniques are a desirable alternative to the time-consuming process of microscopic analysis that is conventionally used in sampling and particle characterization. Here, we report in situ real-time optical scattering measurements of the physical characteristics of airborne bacteria particles following an HTST process in a continuous-flow system. Our results demonstrate that the aerodynamic diameter of bacterial aerosols decreases when exposed to a high-temperature environment, and that the shape of the bacterial cells is significantly altered. These variations in physical characteristics using optical scattering measurements were found to be in agreement with the results of scanning electron microscopy analysis.

Effect of particle hardness on the penetration behavior of fabrics intercalated with dry particles and concentrated particle-fluid suspensions.

PubMed

Kalman, Dennis P; Merrill, Richard L; Wagner, Norman J; Wetzel, Eric D

2009-11-01

The penetration behavior of Kevlar fabric intercalated with dry particles and shear thickening fluids (STF), highly concentrated fluid-particle suspensions, is presented. In particular, the role of particle hardness is explored by comparing fabric treatments containing SiO(2) particles, which are significantly harder than Kevlar, to treatments containing softer poly(methyl methacrylate) (PMMA) particles. The fabric testing includes yarn pull-out, quasi-static spike puncture, and ballistic penetration resistance, performed on single fabric layers. It was found that both dry particle and STF treatments resulted in improvements in fabric properties relative to neat or poly(ethylene glycol) (PEG) treated fabrics. On comparison of treatments with different particle hardness, the SiO(2) materials performed better in all tests than comparable PMMA materials, although the SiO(2) treatments caused yarn failure in pull-out testing, reducing the total pull-out energy. In addition, resistance to yarn pull-out was found to be substantially higher for STF-treated fabrics than for dry particle treated fabrics. However, both dry particle addition and STF treatments exhibited comparable enhancements in puncture and ballistic resistance. These observations suggest that viscous stress transfer, friction, and physical entrainment of hard particles into filaments contribute to the demonstrated improvements in the properties of protective fabrics treated with shear thickening fluids.

Formation of correlated states and tunneling for a low energy and controlled pulsed action on particles

NASA Astrophysics Data System (ADS)

Vysotskii, V. I.; Vysotskyy, M. V.

2017-08-01

We consider a method for optimizing the tunnel effect for low-energy particles by using coherent correlated states formed under controllable pulsed action on these particles. Typical examples of such actions are the effect of a pulsed magnetic field on charged particles in a gas or plasma. Coherent correlated states are characterized most comprehensively by the correlation coefficient r( t); an increase of this factor elevates the probability of particle tunneling through a high potential barrier by several orders of magnitude without an appreciable increase in their energy. It is shown for the first time that the formation of coherent correlated states, as well as maximal | r( t)|max and time-averaged 〈| r( t)|〉 amplitudes of the correlation coefficient and the corresponding tunneling probability are characterized by a nonmonotonic (oscillating) dependence on the forming pulse duration and amplitude. This result makes it possible to optimize experiments on the realization of low-energy nuclear fusion and demonstrates the incorrectness of the intuitive idea that the tunneling probability always increases with the amplitude of an external action on a particle. Our conclusions can be used, in particular, for explaining random (unpredictable and low-repeatability) experimental results on optimization of energy release from nuclear reactions occurring under a pulsed action with fluctuations of the amplitude and duration. We also consider physical premises for the observed dependences and obtain optimal relations between the aforementioned parameters, which ensure the formation of an optimal coherent correlated state and optimal low-energy tunneling in various physical systems with allowance for the dephasing action of a random force. The results of theoretical analysis are compared with the data of successful experiments on the generation of neutrons and alpha particles in an electric discharge in air and gaseous deuterium.

Application of the Junge- and Pankow-equation for estimating indoor gas/particle distribution and exposure to SVOCs

NASA Astrophysics Data System (ADS)

Salthammer, Tunga; Schripp, Tobias

2015-04-01

In the indoor environment, distribution and dynamics of an organic compound between gas phase, particle phase and settled dust must be known for estimating human exposure. This, however, requires a detailed understanding of the environmentally important compound parameters, their interrelation and of the algorithms for calculating partitioning coefficients. The parameters of major concern are: (I) saturation vapor pressure (PS) (of the subcooled liquid); (II) Henry's law constant (H); (III) octanol/water partition coefficient (KOW); (IV) octanol/air partition coefficient (KOA); (V) air/water partition coefficient (KAW) and (VI) settled dust properties like density and organic content. For most of the relevant compounds reliable experimental data are not available and calculated gas/particle distributions can widely differ due to the uncertainty in predicted Ps and KOA values. This is not a big problem if the target compound is of low (<10-6 Pa) or high (>10-2 Pa) volatility, but in the intermediate region even small changes in Ps or KOA will have a strong impact on the result. Moreover, the related physical processes might bear large uncertainties. The KOA value can only be used for particle absorption from the gas phase if the organic portion of the particle or dust is high. The Junge- and Pankow-equation for calculating the gas/particle distribution coefficient KP do not consider the physical and chemical properties of the particle surface area. It is demonstrated by error propagation theory and Monte-Carlo simulations that parameter uncertainties from estimation methods for molecular properties and variations of indoor conditions might strongly influence the calculated distribution behavior of compounds in the indoor environment.

Performance study for a set of BLUE based Filters applied to amplitude estimation using as a reference the single photoelectron signal of the ν-Angra Experiment

NASA Astrophysics Data System (ADS)

Souza, D. M.; Costa, I. A.; Nóbrega, R. A.

2017-10-01

This document presents a detailed study of the performance of a set of digital filters whose implementations are based on the best linear unbiased estimator theory interpreted as a constrained optimization problem that could be relaxed depending on the input signal characteristics. This approach has been employed by a number of recent particle physics experiments for measuring the energy of particle events interacting with their detectors. The considered filters have been designed to measure the peak amplitude of signals produced by their detectors based on the digitized version of such signals. This study provides a clear understanding of the characteristics of those filters in the context of particle physics and, additionally, it proposes a phase related constraint based on the second derivative of the Taylor expansion in order to make the estimator less sensitive to phase variation (phase between the analog signal shaping and its sampled version), which is stronger in asynchronous experiments. The asynchronous detector developed by the ν-Angra Collaboration is used as the basis for this work. Nevertheless, the proposed analysis goes beyond, considering a wide range of conditions related to signal parameters such as pedestal, phase, sampling rate, amplitude resolution, noise and pile-up; therefore crossing the bounds of the ν-Angra Experiment to make it interesting and useful for different asynchronous and even synchronous experiments.

A data transmission method for particle physics experiments based on Ethernet physical layer

NASA Astrophysics Data System (ADS)

Huang, Xi-Ru; Cao, Ping; Zheng, Jia-Jun

2015-11-01

Due to its advantages of universality, flexibility and high performance, fast Ethernet is widely used in readout system design for modern particle physics experiments. However, Ethernet is usually used together with the TCP/IP protocol stack, which makes it difficult to implement readout systems because designers have to use the operating system to process this protocol. Furthermore, TCP/IP degrades the transmission efficiency and real-time performance. To maximize the performance of Ethernet in physics experiment applications, a data readout method based on the physical layer (PHY) is proposed. In this method, TCP/IP is replaced with a customized and simple protocol, which makes it easier to implement. On each readout module, data from the front-end electronics is first fed into an FPGA for protocol processing and then sent out to a PHY chip controlled by this FPGA for transmission. This kind of data path is fully implemented by hardware. From the side of the data acquisition system (DAQ), however, the absence of a standard protocol causes problems for the network related applications. To solve this problem, in the operating system kernel space, data received by the network interface card is redirected from the traditional flow to a specified memory space by a customized program. This memory space can easily be accessed by applications in user space. For the purpose of verification, a prototype system has been designed and implemented. Preliminary test results show that this method can meet the requirements of data transmission from the readout module to the DAQ with an efficient and simple manner. Supported by National Natural Science Foundation of China (11005107) and Independent Projects of State Key Laboratory of Particle Detection and Electronics (201301)

Evidence for surface nucleation: efflorescence of ammonium sulfate and coated ammonium sulfate aerosol particles

NASA Astrophysics Data System (ADS)

Ciobanu, V. Gabriela; Marcolli, Claudia; Krieger, Ulrich K.; Zuend, Andreas; Peter, Thomas

2010-05-01

Aerosol particles are ubiquitous in the atmosphere and can undergo different phase transitions, such as deliquescence and efflorescence. Using optical microscopy, we investigated the efflorescence of ammonium sulfate (AS) in supersaturated AS and 1:1 and 8:1 (by weight) poly(ethylene glycol)-400 (PEG-400)/AS particles, which were deposited as droplets with diameters in the 16 - 35 μm range on a hydrophobically coated slide. The PEG-400/AS particles that are exposed to decreasing relative humidity (RH) exhibit a liquid-liquid phase separation below 90 % RH with the PEG-400 phase surrounding the aqueous AS inner phase (Marcolli and Krieger, 2006; Ciobanu et al., 2009). Pure AS particles effloresced in the RH range from 36.3 to 43.7 % RH, in agreement with literature data (31 - 48 % RH). In contrast, 1:1 PEG-400/AS particles with diameters of the AS phase from 7.2 - 19.2 μm effloresced between 26.8 - 33.9 % RH and 8:1 PEG-400/AS particles with diameters of the AS phase from 1.8 - 7.3 μm between 24.3 - 29.3 % RH. Such low efflorescence relative humidity (ERH) values have never been reached before for AS particles of this size range. We show that neither a potential inhibition of water evaporation via anomalously slow diffusion through the PEG coating, nor the presence of low amounts of PEG-400 in the AS phase, nor different timescales between various experimental techniques could possibly explain the low AS ERH values of PEG-400/AS particles in our setup. High-speed photography of the efflorescence process allowed to monitor the proceeding of the AS crystallization fronts within the particles with millisecond time resolution. The nucleation locations were deduced based on the initial crystals growth locations. Statistical analysis of 31 and 19 efflorescence events for pure AS and 1:1 PEG-400/AS particles, respectively, identified the air/droplet/substrate contact line and the air/droplet interface as preferred nucleation locations in the case of pure AS particles, whereas for 1:1 PEG-400/AS particles preferential AS nucleation in the PEG phase and at the PEG/AS/substrate contact line can be excluded. Based on this statistical analysis of efflorescence events together with the AS ERH values of pure AS and PEG-400/AS particles aforementioned, we suggest that in pure AS particles nucleation starts at the surface of the particles and attribute the lower ERH values observed for PEG-400/AS particles, to the suppression of the surface-induced nucleation process. Our results indicate that surface nucleation may indeed occur in the atmosphere, during AS efflorescence, and might constitute an important, possibly even dominating nucleation pathway. References: Marcolli C. and Krieger U. K., (2006), Journal of Physical Chemistry A, 110(5), 1881-1893. Ciobanu V. G., Marcolli C., Krieger U. K., Weers U., Peter T., (2009), Journal of Physical Chemistry A, 113(41), 10966-10978.

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.

Physics Accomplishments and Future Prospects of the BES Experiments at the Beijing Electron-Positron Collider

NASA Astrophysics Data System (ADS)

Briere, Roy A.; Harris, Frederick A.; Mitchell, Ryan E.

2016-10-01

The cornerstone of the Chinese experimental particle physics program is a series of experiments performed in the τ-charm energy region. China began building e+e- colliders at the Institute for High Energy Physics in Beijing more than three decades ago. Beijing Electron Spectrometer (BES) is the common root name for the particle physics detectors operated at these machines. We summarize the development of the BES program and highlight the physics results across several topical areas.

Rapid, topology-based particle tracking for high-resolution measurements of large complex 3D motion fields.

PubMed

Patel, Mohak; Leggett, Susan E; Landauer, Alexander K; Wong, Ian Y; Franck, Christian

2018-04-03

Spatiotemporal tracking of tracer particles or objects of interest can reveal localized behaviors in biological and physical systems. However, existing tracking algorithms are most effective for relatively low numbers of particles that undergo displacements smaller than their typical interparticle separation distance. Here, we demonstrate a single particle tracking algorithm to reconstruct large complex motion fields with large particle numbers, orders of magnitude larger than previously tractably resolvable, thus opening the door for attaining very high Nyquist spatial frequency motion recovery in the images. Our key innovations are feature vectors that encode nearest neighbor positions, a rigorous outlier removal scheme, and an iterative deformation warping scheme. We test this technique for its accuracy and computational efficacy using synthetically and experimentally generated 3D particle images, including non-affine deformation fields in soft materials, complex fluid flows, and cell-generated deformations. We augment this algorithm with additional particle information (e.g., color, size, or shape) to further enhance tracking accuracy for high gradient and large displacement fields. These applications demonstrate that this versatile technique can rapidly track unprecedented numbers of particles to resolve large and complex motion fields in 2D and 3D images, particularly when spatial correlations exist.

Particle Sorting and Motility Out of Equilibrium

NASA Astrophysics Data System (ADS)

Sandford, Cato

The theory of equilibrium statistical physics, formulated over a century ago, provides an excellent description of physical systems which have reached a static, relaxed state. Such systems can be loosely thought of as maximally disordered, in keeping with the Second Law of Thermodynamics which states that a thermal system in equilibrium has reached a state of highest entropy. However, many entities in the world around us maintain themselves in an remarkably ordered and dynamic state, and must pay for this by producing entropy in their surroundings. Organisms, for example, convert chemical energy (food) into heat, which is then dumped into the environment, raising its entropy. Systems which produce entropy through any mechanism must be described by theories of non-equilibrium statistical physics, for which there currently exists no unified framework or ontology. Here we examine two specific cases of non-equilibrium phenomena from a theoretical perspective. First, we explore the behaviour of microscopic particles which continually dissipate energy to propel themselves through their environment. Second, we consider how devices which distinguish between different types of particles can exploit non-equilibrium processes to enhance their performance. For the case of self-propelled particles, we consider a theoretical model where the particle's propulsion force has "memory"--it is a random process whose instantaneous value depends on its past evolution. This introduces a persistence in the particle's motion, and requires the dissipation of energy into its surroundings. These particles are found to exhibit a variety of behaviours forbidden in equilibrium systems: for instance they may cluster around barriers, exert unbalanced forces, and sustain steady flows through space. We develop the understanding of these particles' dynamics through a combination of explicit calculations, approximations and numerical simulation which characterise and quantify their non-equilibrium behaviour. The second situation investigated concerns the physics of particle-sorting, which is fundamental to biological systems. We introduce a number of model devices designed to distinguish between and segregate two species of particles, and analyse how the quality and speed of their operation may be influenced by providing them with an energy source which pushes them out of equilibrium. We identify different physical regimes, where our devices may consume energy to deliver better results or deliver them faster or both; and we furthermore connect the broader theory of particle sorting to the fundamental theoretical framework of statistical physics.

Scholarly literature and the press: scientific impact and social perception of physics computing

NASA Astrophysics Data System (ADS)

Pia, M. G.; Basaglia, T.; Bell, Z. W.; Dressendorfer, P. V.

2014-06-01

The broad coverage of the search for the Higgs boson in the mainstream media is a relative novelty for high energy physics (HEP) research, whose achievements have traditionally been limited to scholarly literature. This paper illustrates the results of a scientometric analysis of HEP computing in scientific literature, institutional media and the press, and a comparative overview of similar metrics concerning representative particle physics measurements. The picture emerging from these scientometric data documents the relationship between the scientific impact and the social perception of HEP physics research versus that of HEP computing. The results of this analysis suggest that improved communication of the scientific and social role of HEP computing via press releases from the major HEP laboratories would be beneficial to the high energy physics community.

Transcending matter: physics and ultimate meaning.

PubMed

Paulson, Steve; Frank, Adam; Kaiser, David; Maudlin, Tim; Natarajan, Priyamvada

2015-12-01

From the discovery of new galaxies and nearly undetectable dark energy to the quantum entanglement of particles across the universe, new findings in physics naturally elicit a sense of awe and wonder. For the founders of modern physics-from Einstein and Bohr to Heisenberg, Pauli, and Bohm-a fascination with deeper questions of meaning and ultimate reality led some of them to explore esoteric traditions and metaphysics. More recently, however, physicists have largely shunned such philosophical and spiritual associations. What can contemporary physics offer us in the quest to understand our place in the universe? Has physics in some ways become a religion unto itself that rejects the search for existential meaning? Discussion of these and related questions is presented in this paper. © 2015 New York Academy of Sciences.

Theoretical physics: Quarks fuse to release energy

NASA Astrophysics Data System (ADS)

Miller, Gerald A.

2017-11-01

In nuclear fusion, energy is produced by the rearrangement of protons and neutrons. The discovery of an analogue of this process involving particles called quarks has implications for both nuclear and particle physics. See Letter p.89

A Bubble Chamber Simulator: A New Tool for the Physics Classroom

ERIC Educational Resources Information Center

Gagnon, Michel

2011-01-01

Mainly used in the 1960s, bubble chambers played a major role in particle physics. Now replaced with modern electronic detectors, we believe they remain an important didactic tool to introduce particle physics as they provide visual, appealing and insightful pictures. Sadly, this rare type of detector is mostly accessible through open-door events…

Donald Glaser, the Bubble Chamber, and Elementary Particles

Science.gov Websites

Effects of Ionizing Radiation on the Formation of Bubbles in Liquids Physical Review, Vol. 87, Issue 4 , 665, August 15, 1952 Characteristics of Bubble Chambers Physical Review, Vol. 97, Issue 2, 474-479 Chambers Physical Review, Vol. 102, Issue 6, 1653-1658, June 15, 1956 Methods of Particle Detection for

Hands on CERN: A Well-Used Physics Education Project

ERIC Educational Resources Information Center

Johansson, K. E.

2006-01-01

The "Hands on CERN" education project makes it possible for students and teachers to get close to the forefront of scientific research. The project confronts the students with contemporary physics at its most fundamental level with the help of particle collisions from the DELPHI particle physics experiment at CERN. It now exists in 14 languages…

Integration of process diagnostics and three dimensional simulations in thermal spraying

NASA Astrophysics Data System (ADS)

Zhang, Wei

Thermal spraying is a group of processes in which the metallic or ceramic materials are deposited in a molten or semi-molten state on a prepared substrate. In atmospheric plasma spray process, a thermal plasma jet is used to heat up and accelerate loading particles. The process is inherently complex due to the deviation from equilibrium conditions, three dimensional nature, multitude of interrelated variables involved, and stochastic variability at different stages. This dissertation is aimed at understanding the in-flight particle state and plasma plume characteristics in atmospheric plasma spray process through the integration of process diagnostics and three-dimensional simulation. Effects of injection angle and carrier gas flow rate on in-flight particle characteristics are studied experimentally and interpreted through numerical simulation. Plasma jet perturbation by particle injection angle, carrier gas, and particle loading are also identified. Maximum particle average temperature and velocity at any given spray distance is systematically quantified. Optimum plasma plume position for particle injection which was observed in experiments was verified numerically along with description of physical mechanisms. Correlation of spray distance with in-flight particle behavior for various kinds of materials is revealed. A new strategy for visualization and representation of particle diagnostic results for thermal spray processes has been presented. Specifically, 1 st order process maps (process-particle interactions) have been addressed by converting the Temperature-Velocity of particles obtained via diagnostics into non-dimensional group parameters [Melting Index-Reynolds number]. This approach provides an improved description of the thermal and kinetic energy of particles and allows for cross-comparison of diagnostic data within a given process for different materials, comparison of a single material across different thermal spray processes, and detailed assessment of the melting behavior through recourse to analysis of the distributions. An additional group parameter, Oxidation Index, has been applied to relatively track the oxidation extent of metallic particles under different operating conditions. The new mapping strategies have also been proposed in circumstances where only ensemble particle diagnostics are available. Through the integration of process diagnostics and numerical simulation, key issues concerning in-flight particle status as well as the controlling physical mechanisms have been analyzed. A scientific and intellectual strategy for universal description of particle characteristics has been successfully developed.

Particle Fluxes and Bulk Geochemical Characterization of the Cabo Frio Upwelling System in Southeastern Brazil: Sediment Trap Experiments between Spring 2010 and Summer 2012.

PubMed

Albuquerque, Ana Luiza S; Belém, André L; Zuluaga, Francisco J B; Cordeiro, Livia G M; Mendoza, Ursula; Knoppers, Bastiaan A; Gurgel, Marcio H C; Meyers, Philip A; Capilla, Ramsés

2014-05-14

Physical and biogeochemical processes in continental shelves act synergistically in both transporting and transforming suspended material, and ocean dynamics control the dispersion of particles by the coastal zone and their subsequent mixing and dilution within the shelf area constrained by oceanic boundary currents, followed by their gradual settling in a complex sedimentary scenario. One of these regions is the Cabo Frio Upwelling System located in a significantly productive area of Southeastern Brazil, under the control of the nutrient-poor western boundary Brazil Current but also with a wind-driven coastal upwelling zone, inducing cold-water intrusions of South Atlantic Central Water on the shelf. To understand these synergic interactions among physical and biogeochemical processes in the Cabo Frio shelf, a series of four experiments with a total of 98 discrete samples using sediment traps was performed from November 2010 to March 2012, located on the 145 m isobath on the edge of the continental shelf. The results showed that lateral transport might be relevant in some cases, especially in deep layers, although no clear seasonal cycle was detected. Two main physical-geochemical coupling scenarios were identified: singular downwelling events that can enhance particles fluxes and are potentially related to the Brazil Current oscillations; and events of significant fluxes related to the intrusion of the 18°C isotherm in the euphotic zone. The particulate matter settling in the Cabo Frio shelf area seems to belong to multiple marine and terrestrial sources, in which both Paraiba do Sul River and Guanabara Bay could be potential land-sources, although the particulate material might subject intense transformation (diagenesis) during its trajectory to the shelf edge.

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

Developing an in vitro technology to study the inflammation potential of ambient particle types

NASA Astrophysics Data System (ADS)

Haddrell, Allen E.

Elevated levels of suspended particles in the troposphere, termed particulate matter, elicit a myriad of adverse health effects in humans, ranging from shortness of breath and wheezing to myocardial infarction and death. It is currently believed that the adverse health effects associated with particulate matter are mediated by the inflammatory response initiated by the lung following particulate matter inhalation. What remains an area of much interest is elucidating the specific properties of particulate matter, physical or chemical, that cause the upregulation of proinflammatory mediators. The basic premise of this thesis was to identify the specific chemical components of particulate matter responsible for its adverse health effects. To address this issue, instrumentation and methodology were developed wherein one could design, create, levitate and deposit particles of both known chemical composition and size onto lung cells, in vitro, followed by the monitoring of the downstream biological response. An initial study focused on the role of the endotoxin component in particulate matter toxicity. Through a series of blocking studies we found that endotoxin acted synergistically with the particle core to elicit upregulation of proinflammatory mediators, including IL-1beta, TNF-alpha and ICAM-1; all of which are associated with the NF-kappaB pathway. Through characterizing this relatively simple system, one observation became apparent: the presence of the insoluble particle core had a profound effect on the cellular response; that is to say, the particle core was not simply a delivery vector, but a determinant factor in the final intracellular location of the toxic chemical. The latter observation held true as other particle types were studied and in addition, it was found that the nature of the actual chemical species itself plays a dual role in particle toxicity; first by retaining its toxic properties and second by altering the physical properties of the particle. It stems from these findings that the toxicity of the chemical components must be studied in concert and not as individual entities.

Modelling and Dosimetry for Alpha-Particle Therapy

PubMed Central

Sgouros, George; Hobbs, Robert F.; Song, Hong

2015-01-01

As a consequence of the high potency and short range of alpha-particles, radiopharmaceutical therapy with alpha-particle emitting radionuclides is a promising treatment approach that is under active pre-clinical and clinical investigation. To understand and predict the biological effects of alpha-particle radiopharmaceuticals, dosimetry is required at the micro or multi-cellular scale level. At such a scale, highly non-uniform irradiation of the target volume may be expected and the utility of a single absorbed dose value to predict biological effects comes into question. It is not currently possible to measure the pharmacokinetic input required for micro scale dosimetry in humans. Accordingly, pre-clinical studies are required to provide the pharmacokinetic data for dosimetry calculations. The translation of animal data to the human requires a pharmacokinetic model that links macro- and micro-scale pharmacokinetics thereby enabling the extrapolation of micro-scale kinetics from macroscopic measurements. These considerations along with a discussion of the appropriate physical quantity and related units for alpha-particle radiopharmaceutical therapy are examined in this review. PMID:22201712

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.

Noise and diffusion of a vibrated self-propelled granular particle

NASA Astrophysics Data System (ADS)

Walsh, Lee; Wagner, Caleb G.; Schlossberg, Sarah; Olson, Christopher; Baskaran, Aparna; Menon, Narayanan

Granular materials are an important physical realization of active matter. In vibration-fluidized granular matter, both diffusion and self-propulsion derive from the same collisional forcing, unlike many other active systems where there is a clean separation between the origin of single-particle mobility and the coupling to noise. Here we present experimental studies of single-particle motion in a vibrated granular monolayer, along with theoretical analysis that compares grain motion at short and long time scales to the assumptions and predictions, respectively, of the active Brownian particle (ABP) model. The results demonstrate that despite the unique relation between noise and propulsion, granular media do show the generic features predicted by the ABP model and indicate that this is a valid framework to predict collective phenomena. Additionally, our scheme of analysis for validating the inputs and outputs of the model can be applied to other granular and non-granular systems.

Energy-dependent etching-related impacts on CR-39 alpha detection efficiency for the Rn-222 and Rn-220 decay chains

NASA Astrophysics Data System (ADS)

Tan, Y.; Yuan, H.; Kearfott, K. J.

2018-04-01

CR-39 detectors are widely used to measure environmental levels of Rn-222, Rn-220 and their progeny. Prior research reported the CR-39 detection efficiency for alpha particles from Rn-222, Rn-220 and their progeny under a variety of etching conditions. This paper provides an explanation for interesting observations included in that work, namely that the critical incidence angle decreases with the increasing particle energy and the detection efficiency for 8.78 MeV alpha particles is zero. This paper explains these phenomena from a consideration of the interaction of alpha particles with the CR-39 detectors and the physics of etching dynamics. The proposed theory provides a rationale for an approach to optimizing the etching conditions of CR-39 detector for measuring Rn-222, Rn-220 and their progenies.

Dissipative particle dynamics of diffusion-NMR requires high Schmidt-numbers

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

Azhar, Mueed; Greiner, Andreas; Korvink, Jan G., E-mail: jan.korvink@kit.edu, E-mail: david.kauzlaric@imtek.uni-freiburg.de

We present an efficient mesoscale model to simulate the diffusion measurement with nuclear magnetic resonance (NMR). On the level of mesoscopic thermal motion of fluid particles, we couple the Bloch equations with dissipative particle dynamics (DPD). Thereby we establish a physically consistent scaling relation between the diffusion constant measured for DPD-particles and the diffusion constant of a real fluid. The latter is based on a splitting into a centre-of-mass contribution represented by DPD, and an internal contribution which is not resolved in the DPD-level of description. As a consequence, simulating the centre-of-mass contribution with DPD requires high Schmidt numbers. Aftermore » a verification for fundamental pulse sequences, we apply the NMR-DPD method to NMR diffusion measurements of anisotropic fluids, and of fluids restricted by walls of microfluidic channels. For the latter, the free diffusion and the localisation regime are considered.« less

Charged particle concepts for fog dispersion

NASA Technical Reports Server (NTRS)

Frost, W.; Collins, F. G.; Koepf, D.

1981-01-01

Charged particle techniques hold promise for dispersing warm fog in the terminal area of commercial airports. This report focuses on features of the charged particle technique which require further study. The basic physical principles of the technique and the major verification experiments carried out in the past are described. The fundamentals of the nozzle operation are given. The nozzle characteristics and the theory of particle charging in the nozzle are discussed, including information from extensive literature on electrostatic precipitation relative to environmental pollution control and a description of some preliminary reported analyses on the jet characteristics and interaction with neighboring jets. The equation governing the transfer of water substances and of electrical charge is given together with a brief description of several semi-empirical, mathematical expressions necessary for the governing equations. The necessary ingredients of a field experiment to verify the system once a prototype is built are described.

Dust-wall and dust-plasma interaction in the MIGRAINe code

NASA Astrophysics Data System (ADS)

Vignitchouk, L.; Tolias, P.; Ratynskaia, S.

2014-09-01

The physical models implemented in the recently developed dust dynamics code MIGRAINe are described. A major update of the treatment of secondary electron emission, stemming from models adapted to typical scrape-off layer temperatures, is reported. Sputtering and plasma species backscattering are introduced from fits of available experimental data and their relative importance to dust charging and heating is assessed in fusion-relevant scenarios. Moreover, the description of collisions between dust particles and plasma-facing components, based on the approximation of elastic-perfectly plastic adhesive spheres, has been upgraded to take into account the effects of particle size and temperature.

Order of magnitude smaller limit on the electric dipole moment of the electron.

PubMed

Baron, J; Campbell, W C; DeMille, D; Doyle, J M; Gabrielse, G; Gurevich, Y V; Hess, P W; Hutzler, N R; Kirilov, E; Kozyryev, I; O'Leary, B R; Panda, C D; Parsons, M F; Petrik, E S; Spaun, B; Vutha, A C; West, A D

2014-01-17

The Standard Model of particle physics is known to be incomplete. Extensions to the Standard Model, such as weak-scale supersymmetry, posit the existence of new particles and interactions that are asymmetric under time reversal (T) and nearly always predict a small yet potentially measurable electron electric dipole moment (EDM), d(e), in the range of 10(-27) to 10(-30) e·cm. The EDM is an asymmetric charge distribution along the electron spin (S(→)) that is also asymmetric under T. Using the polar molecule thorium monoxide, we measured d(e) = (-2.1 ± 3.7stat ± 2.5syst) × 10(-29) e·cm. This corresponds to an upper limit of |d(e)| < 8.7 × 10(-29) e·cm with 90% confidence, an order of magnitude improvement in sensitivity relative to the previous best limit. Our result constrains T-violating physics at the TeV energy scale.

Fifteen symposia on microdosimetry: implications for modern particle-beam cancer radiotherapy.

PubMed

Wambersie, A; Menzel, H; Gueulette, J; Pihet, P

2015-09-01

The objective of microdosimetry was, and still is, to identify physical descriptions of the initial physical processes of ionising radiation interacting with biological matter which correlate with observed radiobiological effects with a view to improve the understanding of radiobiological mechanisms and effects. The introduction of therapy with particles starting with fast neutrons followed by negative pions, protons and light ions necessitated the application of biological weighting factors for absorbed dose in order to account for differences of the relative biological effectiveness (RBE). Dedicated radiobiological experiments in therapy beams with mammalian cells and with laboratory animals provided sets of RBE values which are used to evaluate empirical 'clinical RBE values'. The combination of such experiments with microdosimetric measurements in identical conditions offered the possibility to establish semi-empirical relationships between microdosimetric parameters and results of RBE studies. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

High-fidelity plasma codes for burn physics

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

Cooley, James; Graziani, Frank; Marinak, Marty

Accurate predictions of equation of state (EOS), ionic and electronic transport properties are of critical importance for high-energy-density plasma science. Transport coefficients inform radiation-hydrodynamic codes and impact diagnostic interpretation, which in turn impacts our understanding of the development of instabilities, the overall energy balance of burning plasmas, and the efficacy of self-heating from charged-particle stopping. Important processes include thermal and electrical conduction, electron-ion coupling, inter-diffusion, ion viscosity, and charged particle stopping. However, uncertainties in these coefficients are not well established. Fundamental plasma science codes, also called high-fidelity plasma codes, are a relatively recent computational tool that augments both experimental datamore » and theoretical foundations of transport coefficients. This paper addresses the current status of HFPC codes and their future development, and the potential impact they play in improving the predictive capability of the multi-physics hydrodynamic codes used in HED design.« less

What Will the Neighbors Think? Building Large-Scale Science Projects Around the World

ScienceCinema

Jones, Craig; Mrotzek, Christian; Toge, Nobu; Sarno, Doug

2017-12-22

Public participation is an essential ingredient for turning the International Linear Collider into a reality. Wherever the proposed particle accelerator is sited in the world, its neighbors -- in any country -- will have something to say about hosting a 35-kilometer-long collider in their backyards. When it comes to building large-scale physics projects, almost every laboratory has a story to tell. Three case studies from Japan, Germany and the US will be presented to examine how community relations are handled in different parts of the world. How do particle physics laboratories interact with their local communities? How do neighbors react to building large-scale projects in each region? How can the lessons learned from past experiences help in building the next big project? These and other questions will be discussed to engage the audience in an active dialogue about how a large-scale project like the ILC can be a good neighbor.

Effect of photochemical ageing on the ice nucleation properties of diesel and wood burning particles

NASA Astrophysics Data System (ADS)

Chou, C.; Kanji, Z. A.; Stetzer, O.; Tritscher, T.; Chirico, R.; Heringa, M. F.; Weingartner, E.; Prévôt, A. S. H.; Baltensperger, U.; Lohmann, U.

2013-01-01

A measurement campaign (IMBALANCE) conducted in 2009 was aimed at characterizing the physical and chemical properties of freshly emitted and photochemically aged combustion particles emitted from a log wood burner and diesel vehicles: a EURO3 Opel Astra with a diesel oxidation catalyst (DOC) but no particle filter and a EURO2 Volkswagen Transporter TDI Syncro without emission aftertreatment. Ice nucleation experiments in the deposition and condensation freezing modes were conducted with the Portable Ice Nucleation Chamber (PINC) at three nominal temperatures, -30 °C, -35 °C and -40 °C. Freshly emitted diesel particles showed ice formation only at -40 °C in the deposition mode at 137% relative humidity with respect to ice (RHi) and 92% relative humidity with respect to water (RHw), and photochemical ageing did not play a role in modifying their ice nucleation behaviour. Only one diesel experiment where α-pinene was added for the ageing process, showed an ice nucleation enhancement at -35 °C. Wood burning particles also act as ice nuclei (IN) at -40 °C in the deposition mode at the same conditions as for diesel particles and photochemical ageing also did not alter the ice formation properties of the wood burning particles. Unlike diesel particles, wood burning particles form ice via condensation freezing at -35 °C whereas no ice nucleation was observed at -30 °C. Photochemical ageing did not affect the ice nucleation ability of the diesel and wood burning particles at the three different temperatures investigated but a broader range of temperatures below -40 °C need to be investigated in order to draw an overall conclusion on the effect of photochemical ageing on deposition/condensation ice nucleation across the entire temperature range relevant to cold clouds.

Individual Aerosol Particle Types Produced by Savanna Burning

NASA Astrophysics Data System (ADS)

Posfai, M.; Simonics, R.; Li, J.; Hobbs, P. V.; Buseck, P. R.; Buseck, P. R.

2001-12-01

We used analytical transmission electron microscopy (TEM) to study individual aerosol particles that were collected on the University of Washington Convair-580 research aircraft over southern Africa during the Safari2000 Dry Season Experiment. Our goals were to study the compositions, morphologies, and mixing states of carbonaceous particles, in order to better understand the physical and chemical properties of biomass smoke on the individual-particle level. The compositions of single particles were determined using energy-dispersive x-ray spectrometry (EDS) and electron energy-loss spectroscopy (EELS). Energy-loss maps obtained with the TEM are useful for studying the spatial distribution of light elements such as carbon within the particles; thus, they provide a detailed picture of complex particles. Carbonaceous particles were assigned into three main groups on the basis of morphology and composition: "organic particles with inorganic inclusions," "tar balls," and "soot." Soot is recognized by its characteristic morphology and microstructure. The distinction between "organic particles with inorganic inclusions" and "tar balls" is somewhat arbitrary, since the two criteria that are used for their distinction (composition and aspect ratio) change continually. The relative concentrations of the three major particle types vary with the type of fire and distance from fire. In the plume of a smoldering fire west of Beria (August 31) the relative concentration of tar balls increased with aging of the plume. Tar balls have a fairly narrow size distribution with a maximum between 100 and 200 nm (diameter). The inorganic K-salt inclusions (KCl, K2SO4, KNO3) within "organic particles" should make these particles hygroscopic, regardless of the properties of the organic compounds. Aging causes the conversion of KCl into K2SO4, KNO3. Aerosol production from flaming and smoldering fires was compared over Kruger National Park on August 17; more soot and more Cl-rich inclusions in organic particles were produced by the flaming fire than by the smoldering fire. Further sets of samples from other flights of Safari2000 are being studied.

The Multiverse and Particle Physics

NASA Astrophysics Data System (ADS)

Donoghue, John F.

2016-10-01

The possibility of fundamental theories with very many ground states, each with different physical parameters, changes the way that we approach the major questions of particle physics. Most importantly, it raises the possibility that these different parameters could be realized in different domains in the larger universe. In this review, I survey the motivations for the multiverse and the impact of the idea of the multiverse on the search for new physics beyond the Standard Model.

Scaling effects in direct shear tests

USGS Publications Warehouse

Orlando, A.D.; Hanes, D.M.; Shen, H.H.

2009-01-01

Laboratory experiments of the direct shear test were performed on spherical particles of different materials and diameters. Results of the bulk friction vs. non-dimensional shear displacement are presented as a function of the non-dimensional particle diameter. Simulations of the direct shear test were performed using the Discrete Element Method (DEM). The simulation results show Considerable differences with the physical experiments. Particle level material properties, such as the coefficients of static friction, restitution and rolling friction need to be known a priori in order to guarantee that the simulation results are an accurate representation of the physical phenomenon. Furthermore, laboratory results show a clear size dependency on the results, with smaller particles having a higher bulk friction than larger ones. ?? 2009 American Institute of Physics.

Comparisons of physical experiment and discrete element simulations of sheared granular materials in an annular shear cell

USGS Publications Warehouse

Ji, S.; Hanes, D.M.; Shen, H.H.

2009-01-01

In this study, we report a direct comparison between a physical test and a computer simulation of rapidly sheared granular materials. An annular shear cell experiment was conducted. All parameters were kept the same between the physical and the computational systems to the extent possible. Artificially softened particles were used in the simulation to reduce the computational time to a manageable level. Sensitivity study on the particle stiffness ensured such artificial modification was acceptable. In the experiment, a range of normal stress was applied to a given amount of particles sheared in an annular trough with a range of controlled shear speed. Two types of particles, glass and Delrin, were used in the experiment. Qualitatively, the required torque to shear the materials under different rotational speed compared well with those in the physical experiments for both the glass and the Delrin particles. However, the quantitative discrepancies between the measured and simulated shear stresses were nearly a factor of two. Boundary conditions, particle size distribution, particle damping and friction, including a sliding and rolling, contact force model, were examined to determine their effects on the computational results. It was found that of the above, the rolling friction between particles had the most significant effect on the macro stress level. This study shows that discrete element simulation is a viable method for engineering design for granular material systems. Particle level information is needed to properly conduct these simulations. However, not all particle level information is equally important in the study regime. Rolling friction, which is not commonly considered in many discrete element models, appears to play an important role. ?? 2009 Elsevier Ltd.

The Space Time Asymmetry Research Mission

NASA Astrophysics Data System (ADS)

Scargle, Jeffrey; Goebel, John; Buchman, Sasha; Byer, Robert; Sun, Ke-Xun; Lipa, John; Chu-Thielbar, Lisa; Hall, John

We will use precision molecular iodine stabilized Nd:YAG laser interferometers to search for small deviations from Lorentz Invariance, a cornerstone of relativity and particle physics, and thus our understanding of the Universe. A Lorentz violation would have profound implications for cosmology and particle physics. An improved null result will constrain theories attempting to unite particle physics and gravity. Science Objectives: Measure the absolute anisotropy of the velocity of light to 10-18 (100-fold improvement) Derive the Michelson-Morley coefficient to 10-12 (100-fold improvement) Derive the Kennedy-Thorndyke coefficient to 7x10-10 (400-fold improvement) Derive the coefficients of Lorentz violation in the Standard Model Extension, in the range 7x10-18 to 10-14 (50 to 500-fold improvement) Thermal control, stabilization and uniformitization are great concerns, so new technology has been devised that keeps these parameters within strict specified limits. Thereby STAR is able to operate effectively in all possible orbits. The spacecraft is based on a bus development by NASA Ames Research Center. STAR is designed to fly as a secondary payload on a Delta IV launch vehicle with an ESPA ring into an 850 km circular orbit. It will have a one-year mission and is capable of even longer duration. Other orbit options are possible depending on the launch opportunities available. The STAR project is a partnership between Stanford University, NASA Ames Research Center and NASA Goddard Space Flight Center.

Novel Quantum Criticality in Two Dimensional Topological Phase transitions

PubMed Central

Cho, Gil Young; Moon, Eun-Gook

2016-01-01

Topological quantum phase transitions intrinsically intertwine self-similarity and topology of many-electron wave-functions, and divining them is one of the most significant ways to advance understanding in condensed matter physics. Our focus is to investigate an unconventional class of the transitions between insulators and Dirac semimetals whose description is beyond conventional pseudo relativistic Dirac Hamiltonian. At the transition without the long-range Coulomb interaction, the electronic energy dispersion along one direction behaves like a relativistic particle, linear in momentum, but along the other direction it behaves like a non-relativistic particle, quadratic in momentum. Various physical systems ranging from TiO2-VO2 heterostructure to organic material α-(BEDT-TTF)2I3 under pressure have been proposed to have such anisotropic dispersion relation. Here, we discover a novel quantum criticality at the phase transition by incorporating the long range Coulomb interaction. Unique interplay between the Coulomb interaction and electronic critical modes enforces not only the anisotropic renormalization of the Coulomb interaction but also marginally modified electronic excitation. In connection with experiments, we investigate several striking effects in physical observables of our novel criticality. PMID:26791803

The effect of a radial electric field on ripple-trapped ions observed by neutral particle fluxes

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

Heikkinen, J.A.; Herrmann, W.; Kurki-Suonio, T.

1997-10-01

The effect of a radial electric field on nonthermal ripple-trapped ions is investigated using toroidal Monte Carlo simulations for edge tokamak plasmas. The increase in the neutral particle flux from the ions trapped in local magnetic wells observed by the charge exchange (CX) detector at a low confinement to high confinement transition at ASDEX (Axially Symmetric Divertor Experiment). Upgrade tokamak [{ital Proceedings of the 20th European Conference on Controlled Fusion and Plasma Physics}, Lisbon (European Physical Society, Petit-Lancy, Switzerland, 1993), Vol. 17C, Part I, p. 267] is reproduced in the simulations by turning on a radial electric field near themore » plasma periphery. The poloidal and toroidal angles at which the CX detector signal is most sensitive to the radial electric field are determined. A fast response time of the signal in the range of 50{endash}100 {mu}s to the appearance of the electric field can be found in the simulations with a relatively large half-width of the negative electric field region. {copyright} {ital 1997 American Institute of Physics.}« less

Physical cleaning by bubbly streaming flow in an ultrasound field

NASA Astrophysics Data System (ADS)

Yamashita, Tatsuya; Ando, Keita

2017-11-01

Low-intensity ultrasonic cleaning with gas-supersaturated water is a promising method of physical cleaning without erosion; we are able to trigger cavitation bubble nucleation by weak ultrasound under gas supersaturation and thus clean material surfaces by mild bubble dynamics. Here, we perform particle image velocimetry (PIV) measurement of liquid flow and cavitation bubble translation in an ultrasonic cleaning bath driven at 28 kHz and then relate it to cleaning tests using glass slides at which silica particles are attached. The ultrasound pressure amplitude at the cleaning spot is set at 1.4 atm. We select the supersaturation level of dissolved oxygen (DO) as a parameter and control it by oxygen microbubble aeration. It follows from the PIV measurement that the liquid flow is enhanced by the cavitation bubble translation driven by acoustic radiation force; this trend becomes clearer when the bubbles appear more densely as the DO supersaturation increases. In the cleaning tests, the cleaned areas appear as straight streaks. This suggests that physical cleaning is achieved mainly by cavitation bubbles that translate in ultrasound fields.

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

PubMed

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Bartusik, Dorota; Greer, Alexander; Lyons, Alan M

2014-11-13

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon-phthalocyanine (Pc) particles are immobilized. Singlet oxygen ((1)O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV-vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid-gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

LiNbO{sub 3}: A photovoltaic substrate for massive parallel manipulation and patterning of nano-objects

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

Carrascosa, M.; García-Cabañes, A.; Jubera, M.

The application of evanescent photovoltaic (PV) fields, generated by visible illumination of Fe:LiNbO{sub 3} substrates, for parallel massive trapping and manipulation of micro- and nano-objects is critically reviewed. The technique has been often referred to as photovoltaic or photorefractive tweezers. The main advantage of the new method is that the involved electrophoretic and/or dielectrophoretic forces do not require any electrodes and large scale manipulation of nano-objects can be easily achieved using the patterning capabilities of light. The paper describes the experimental techniques for particle trapping and the main reported experimental results obtained with a variety of micro- and nano-particles (dielectricmore » and conductive) and different illumination configurations (single beam, holographic geometry, and spatial light modulator projection). The report also pays attention to the physical basis of the method, namely, the coupling of the evanescent photorefractive fields to the dielectric response of the nano-particles. The role of a number of physical parameters such as the contrast and spatial periodicities of the illumination pattern or the particle deposition method is discussed. Moreover, the main properties of the obtained particle patterns in relation to potential applications are summarized, and first demonstrations reviewed. Finally, the PV method is discussed in comparison to other patterning strategies, such as those based on the pyroelectric response and the electric fields associated to domain poling of ferroelectric materials.« less

Fast Particle Methods for Multiscale Phenomena Simulations

NASA Technical Reports Server (NTRS)

Koumoutsakos, P.; Wray, A.; Shariff, K.; Pohorille, Andrew

2000-01-01

We are developing particle methods oriented at improving computational modeling capabilities of multiscale physical phenomena in : (i) high Reynolds number unsteady vortical flows, (ii) particle laden and interfacial flows, (iii)molecular dynamics studies of nanoscale droplets and studies of the structure, functions, and evolution of the earliest living cell. The unifying computational approach involves particle methods implemented in parallel computer architectures. The inherent adaptivity, robustness and efficiency of particle methods makes them a multidisciplinary computational tool capable of bridging the gap of micro-scale and continuum flow simulations. Using efficient tree data structures, multipole expansion algorithms, and improved particle-grid interpolation, particle methods allow for simulations using millions of computational elements, making possible the resolution of a wide range of length and time scales of these important physical phenomena.The current challenges in these simulations are in : [i] the proper formulation of particle methods in the molecular and continuous level for the discretization of the governing equations [ii] the resolution of the wide range of time and length scales governing the phenomena under investigation. [iii] the minimization of numerical artifacts that may interfere with the physics of the systems under consideration. [iv] the parallelization of processes such as tree traversal and grid-particle interpolations We are conducting simulations using vortex methods, molecular dynamics and smooth particle hydrodynamics, exploiting their unifying concepts such as : the solution of the N-body problem in parallel computers, highly accurate particle-particle and grid-particle interpolations, parallel FFT's and the formulation of processes such as diffusion in the context of particle methods. This approach enables us to transcend among seemingly unrelated areas of research.

Basics of particle therapy I: physics

PubMed Central

Park, Seo Hyun

2011-01-01

With the advance of modern radiation therapy technique, radiation dose conformation and dose distribution have improved dramatically. However, the progress does not completely fulfill the goal of cancer treatment such as improved local control or survival. The discordances with the clinical results are from the biophysical nature of photon, which is the main source of radiation therapy in current field, with the lower linear energy transfer to the target. As part of a natural progression, there recently has been a resurgence of interest in particle therapy, specifically using heavy charged particles, because these kinds of radiations serve theoretical advantages in both biological and physical aspects. The Korean government is to set up a heavy charged particle facility in Korea Institute of Radiological & Medical Sciences. This review introduces some of the elementary physics of the various particles for the sake of Korean radiation oncologists' interest. PMID:22984664

Characterisation of particle emissions from the driving car fleet and the contribution to ambient and indoor particle concentrations

NASA Astrophysics Data System (ADS)

Palmgren, Finn; Wåhlin, Peter; Kildesø, Jan; Afshari, Alireza; Fogh, Christian L.

The population is mainly exposed to high air pollution concentrations in the urban environment, where motor vehicle emissions constitute the main source of fine and ultrafine particles. These particles can penetrate deep into the respiratory system, and studies indicate that the smaller the particle, the larger the health impacts. The chemical composition, surface reactivity and physical properties are also important. However, the knowledge about chemical and physical properties of particles and the temporal and spatial variability of the smallest particles is still very limited. The present study summarises the first results of a larger project with the aims to improve the knowledge. The concentration and the emissions of ultrafine particles from petrol and diesel vehicles, respectively, have been quantified using Scanning Mobility Particle Sizer of ultrafine particles in the size range 6-700 nm and routine monitoring data from urban streets and urban background in Denmark. The quantification was carried out using receptor modelling. The number size distributions of petrol and diesel emissions showed a maximum at 20-30 nm and non-traffic at ≈100 nm. The contribution of ultrafine particles from diesel vehicles is dominating in streets. The same technique has been applied on PM 10, and ≈50% contribution from non-traffic. The technique has also been introduced in relation to elemental and organic carbon, and the first data showed strong correlation between traffic pollution and elemental carbon. The outdoor air quality has a significant effect on indoor pollution levels, and we spend most of the time indoors. Knowledge about the influence of ambient air pollution on the concentrations in the indoor environment is therefore crucial for assessment of human health effects of traffic pollution. The results of our studies will be included in air quality models for calculation of human exposure. Preliminary results from our first campaign showed, that the deposition rate of particles in the apartment is negligible in the particle size range 100-500 nm. In the size range below 100 nm the deposition rate increases with decreasing particle diameter to a value of approximately 1 h -1 at 10 nm. The penetration efficiency shows a maximum of 60% at 100 nm. More detailed studies of exchange of particles in outdoor/indoor air and the transformation are planned to take place during three next campaigns.

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.

A square-force cohesion model and its extraction from bulk measurements

NASA Astrophysics Data System (ADS)

Liu, Peiyuan; Lamarche, Casey; Kellogg, Kevin; Hrenya, Christine

2017-11-01

Cohesive particles remain poorly understood, with order of magnitude differences exhibited for prior, physical predictions of agglomerate size. A major obstacle lies in the absence of robust models of particle-particle cohesion, thereby precluding accurate prediction of the behavior of cohesive particles. Rigorous cohesion models commonly contain parameters related to surface roughness, to which cohesion shows extreme sensitivity. However, both roughness measurement and its distillation into these model parameters are challenging. Accordingly, we propose a ``square-force'' model, where cohesive force remains constant until a cut-off separation. Via DEM simulations, we demonstrate validity of the square-force model as surrogate of more rigorous models, when its two parameters are selected to match the two key quantities governing dense and dilute granular flows, namely maximum cohesive force and critical cohesive energy, respectively. Perhaps more importantly, we establish a method to extract the parameters in the square-force model via defluidization, due to its ability to isolate the effects of the two parameters. Thus, instead of relying on complicated scans of individual grains, determination of particle-particle cohesion from simple bulk measurements becomes feasible. Dow Corning Corporation.

Extension of a coarse grained particle method to simulate heat transfer in fluidized beds

DOE PAGES

Lu, Liqiang; Morris, Aaron; Li, Tingwen; ...

2017-04-18

The heat transfer in a gas-solids fluidized bed is simulated with computational fluid dynamic-discrete element method (CFD-DEM) and coarse grained particle method (CGPM). In CGPM fewer numerical particles and their collisions are tracked by lumping several real particles into a computational parcel. Here, the assumption is that the real particles inside a coarse grained particle (CGP) are made from same species and share identical physical properties including density, diameter and temperature. The parcel-fluid convection term in CGPM is calculated using the same method as in DEM. For all other heat transfer mechanisms, we derive in this study mathematical expressions thatmore » relate the new heat transfer terms for CGPM to those traditionally derived in DEM. This newly derived CGPM model is verified and validated by comparing the results with CFD-DEM simulation results and experiment data. The numerical results compare well with experimental data for both hydrodynamics and temperature profiles. Finally, the proposed CGPM model can be used for fast and accurate simulations of heat transfer in large scale gas-solids fluidized beds.« less

Extension of a coarse grained particle method to simulate heat transfer in fluidized beds

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

Lu, Liqiang; Morris, Aaron; Li, Tingwen

The heat transfer in a gas-solids fluidized bed is simulated with computational fluid dynamic-discrete element method (CFD-DEM) and coarse grained particle method (CGPM). In CGPM fewer numerical particles and their collisions are tracked by lumping several real particles into a computational parcel. Here, the assumption is that the real particles inside a coarse grained particle (CGP) are made from same species and share identical physical properties including density, diameter and temperature. The parcel-fluid convection term in CGPM is calculated using the same method as in DEM. For all other heat transfer mechanisms, we derive in this study mathematical expressions thatmore » relate the new heat transfer terms for CGPM to those traditionally derived in DEM. This newly derived CGPM model is verified and validated by comparing the results with CFD-DEM simulation results and experiment data. The numerical results compare well with experimental data for both hydrodynamics and temperature profiles. Finally, the proposed CGPM model can be used for fast and accurate simulations of heat transfer in large scale gas-solids fluidized beds.« less

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

Schulte, R.

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

TU-G-BRB-05: Panel Discussion: Clinical Trials in Proton and Ion Therapy - Are We Ready?

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

Schulte, R.

2015-06-15

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

TU-G-BRB-03: IROC Houston’s Proton Beam Validation for Clinical Trials

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

Taylor, P.

2015-06-15

Proton therapy, in particular, and ion therapy, just beginning, are becoming an increasing focus of attention in clinical radiation oncology and medical physics. Both modalities have been criticized of lacking convincing evidence from randomized trials proving their efficacy, justifying the higher costs involved in these therapies. This session will provide an overview of the current status of clinical trials in proton therapy, including recent developments in ion therapy. As alluded to in the introductory talk by Dr. Schulte, opinions are diverging widely as to the usefulness and need for clinical trials in particle therapy and the challenge of equipoise. Themore » lectures will highlight some of the challenges that surround clinical trials in particle therapy. One, presented by Dr. Choy from UT Southwestern, is that new technology and even different types of particles such as helium and carbon ions are introduced into this environment, increasing the phase space of clinical variables. The other is the issue of medical physics quality assurance with physical phantoms, presented by Mrs. Taylor from IROC Houston, which is more challenging because 3D and 4D image guidance and active delivery techniques are in relatively early stages of development. The role of digital phantoms in developing clinical treatment planning protocols and as a QA tool will also be highlighted by Dr. Lee from NCI. The symposium will be rounded off by a panel discussion among the Symposium speakers, arguing pro or con the need and readiness for clinical trials in proton and ion therapy. Learning Objectives: To get an update on the current status of clinical trials allowing or mandating proton therapy. Learn about the status of planned clinical trials in the U.S. and worldwide involving ion therapy. Discuss the challenges in the design and QA of clinical trials in particle therapy. Learn about existing and future physical and computational anthropomorphic phantoms for charged particle clinical trial development and support. Research reported in this presentation is supported by the National Cancer Institute of the National; Institutes of Health under Award Number P20CA183640.« less

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.

Constraints on Particle Sizes in Saturn's G Ring from Ring Plane Crossing Observations

NASA Astrophysics Data System (ADS)

Throop, H. B.; Esposito, L. W.

1996-09-01

The ring plane crossings in 1995--96 allowed earth-based observations of Saturn's diffuse rings (Nicholson et al., Nature 272, 1996; De Pater et al. Icarus 121, 1996) at a phase angle of alpha ~ 5 deg . We calculate the G ring reflectance for steady state distributions of dust to km-sized bodies from a range of physical models which track the evolution of the G ring from its initial formation following the disruption of a progenitor satellite (Canup & Esposito 1996, \\ Icarus,\\ in press). We model scattering from the ring's small particles using an exact T-matrix method for nonspherical, absorptive particles (Mishchenko et al. 1996, \\ JGR Atmo., in press), large particles using the phase function and spectrum of Europa, and intermediate particles using a linear combination of the small and large limits. Two distinct particle size distributions from the CE96 model fit the observed spectrum. The first is that of a dusty ring, with the majority of ring reflectance in dust particles of relatedly shallow power law size distribution exponent q ~ 2.5. The second has equal reflectances from a) dust in the range q ~ 3.5 -- 6.5 and b) macroscopic bodies > 1 mm. In this second case, the respective slightly blue and red components combine to form the observed relatively flat spectrum. Although light scattering in backscatter is not sufficient to completely constrain the G ring size distribution, the distributions predicted by the CE96 model can explain the earth-based observations.

Specification of the near-Earth space environment with SHIELDS

DOE PAGES

Jordanova, Vania Koleva; Delzanno, Gian Luca; Henderson, Michael Gerard; ...

2017-11-26

Here, predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure is one example of “space weather” and a big space physics challenge. A project recently funded through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- andmore » micro-scale. Important physics questions related to particle injection and acceleration associated with magnetospheric storms and substorms, as well as plasma waves, are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. A full two-way coupling of physics-based models across multiple scales, including a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D) and an inner magnetosphere (RAM-SCB) codes, is achieved. New data assimilation techniques employing in situ satellite data are developed; these provide an order of magnitude improvement in the accuracy in the simulation of the SCE. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code that can be used for reanalysis of satellite failures or for satellite design.« less

Specification of the near-Earth space environment with SHIELDS

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

Jordanova, Vania Koleva; Delzanno, Gian Luca; Henderson, Michael Gerard

Here, predicting variations in the near-Earth space environment that can lead to spacecraft damage and failure is one example of “space weather” and a big space physics challenge. A project recently funded through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program aims at developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to understand the dynamics of the surface charging environment (SCE), the hot (keV) electrons representing the source and seed populations for the radiation belts, on both macro- andmore » micro-scale. Important physics questions related to particle injection and acceleration associated with magnetospheric storms and substorms, as well as plasma waves, are investigated. These challenging problems are addressed using a team of world-class experts in the fields of space science and computational plasma physics, and state-of-the-art models and computational facilities. A full two-way coupling of physics-based models across multiple scales, including a global MHD (BATS-R-US) embedding a particle-in-cell (iPIC3D) and an inner magnetosphere (RAM-SCB) codes, is achieved. New data assimilation techniques employing in situ satellite data are developed; these provide an order of magnitude improvement in the accuracy in the simulation of the SCE. SHIELDS also includes a post-processing tool designed to calculate the surface charging for specific spacecraft geometry using the Curvilinear Particle-In-Cell (CPIC) code that can be used for reanalysis of satellite failures or for satellite design.« less

Reviews Book: Nucleus Book: The Wonderful World of Relativity Book: Head Shot Book: Cosmos Close-Up Places to Visit: Physics DemoLab Book: Quarks, Leptons and the Big Bang EBook: Shooting Stars Equipment: Victor 70C USB Digital Multimeter Web Watch

NASA Astrophysics Data System (ADS)

2012-09-01

WE RECOMMEND Nucleus: A Trip into the Heart of Matter A coffee-table book for everyone to dip into and learn from The Wonderful World of Relativity A charming, stand-out introduction to relativity The Physics DemoLab, National University of Singapore A treasure trove of physics for hands-on science experiences Quarks, Leptons and the Big Bang Perfect to polish up on particle physics for older students Victor 70C USB Digital Multimeter Equipment impresses for usability and value WORTH A LOOK Cosmos Close-Up Weighty tour of the galaxy that would make a good display Shooting Stars Encourage students to try astrophotography with this ebook HANDLE WITH CARE Head Shot: The Science Behind the JKF Assassination Exploration of the science behind the crime fails to impress WEB WATCH App-lied science for education: a selection of free Android apps are reviewed and iPhone app options are listed

Protocol for Direct Counterfactual Quantum Communication

NASA Astrophysics Data System (ADS)

Salih, Hatim; Li, Zheng-Hong; Al-Amri, M.; Zubairy, M. Suhail

2013-04-01

It has long been assumed in physics that for information to travel between two parties in empty space, “Alice” and “Bob,” physical particles have to travel between them. Here, using the “chained” quantum Zeno effect, we show how, in the ideal asymptotic limit, information can be transferred between Alice and Bob without any physical particles traveling between them.

Particle-fluid interactions for flow measurements

NASA Technical Reports Server (NTRS)

Berman, N. S.

1973-01-01

Study has been made of the motion of single particle and of group of particles, emphasizing solid particles in gaseous fluid. Velocities of fluid and particle are compared for several conditions of physical interest. Mean velocity and velocity fluctuations are calculated for single particle, and some consideration is given to multiparticle systems.

Matter and Interactions: A Particle Physics Perspective

ERIC Educational Resources Information Center

Organtini, Giovanni

2011-01-01

In classical mechanics, matter and fields are completely separated; matter interacts with fields. For particle physicists this is not the case; both matter and fields are represented by particles. Fundamental interactions are mediated by particles exchanged between matter particles. In this article we explain why particle physicists believe in…

Long Pulse Operation on Tore-Supra: Towards Steady State

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

Moreau, P.; Bucalossi, J.; Brosset, C.

The experimental programme of Tore Supra is devoted to the study of technology and physics issues associated to long-duration high performance discharges. This new domain of operation requires simultaneously and in steady state: heat removal capability, particle exhaust, fully non-inductive current drive, advanced technology integration and real time plasma control. The long discharge allows for addressing new time scale physic such as the wall particle retention and erosion. Moreover, the physics of fully non-inductive discharges is full of novelty, namely: the MHD stability, the slow spontaneous oscillation of the central electron temperature or the outstanding inward particle pinch.

Exploring the SCOAP3 Research Contributions of the United States

NASA Astrophysics Data System (ADS)

Marsteller, Matthew

2016-03-01

The Sponsoring Consortium for Open Access Publishing in Particle Physics (SCOAP3) is a successful global partnership of libraries, funding agencies and research centers. This presentation will inform the audience about SCOAP3 and also delve into descriptive statistics of the United States' intellectual contribution to particle physics via these open access journals. Exploration of the SCOAP3 particle physics literature using a variety of metrics tools such as Web of Science™, InCites™, Scopus® and SciVal will be shared. ORA or Sci2 will be used to visualize author collaboration networks.

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

LAGASSE,ROBERT R.; THOMPSON,KYLE R.

The goal of this work is to develop techniques for measuring gradients in particle concentration within filled polymers, such as encapsulant. A high concentration of filler particles is added to such materials to tailor physical properties such as thermal expansion coefficient. Sedimentation and flow-induced migration of particles can produce concentration gradients that are most severe near material boundaries. Therefore, techniques for measuring local particle concentration should be accurate near boundaries. Particle gradients in an alumina-filled epoxy resin are measured with a spatial resolution of 0.2 mm using an x-ray beam attenuation technique, but an artifact related to the finite diametermore » of the beam reduces accuracy near the specimen's edge. Local particle concentration near an edge can be measured more reliably using microscopy coupled with image analysis. This is illustrated by measuring concentration profiles of glass particles having 40 {micro}m median diameter using images acquired by a confocal laser fluorescence microscope. The mean of the measured profiles of volume fraction agrees to better than 3% with the expected value, and the shape of the profiles agrees qualitatively with simple theory for sedimentation of monodisperse particles. Extending this microscopy technique to smaller, micron-scale filler particles used in encapsulant for microelectronic devices is illustrated by measuring the local concentration of an epoxy resin containing 0.41 volume fraction of silica.« less

Scale relativity: from quantum mechanics to chaotic dynamics.

NASA Astrophysics Data System (ADS)

Nottale, L.

Scale relativity is a new approach to the problem of the origin of fundamental scales and of scaling laws in physics, which consists in generalizing Einstein's principle of relativity to the case of scale transformations of resolutions. We recall here how it leads one to the concept of fractal space-time, and to introduce a new complex time derivative operator which allows to recover the Schrödinger equation, then to generalize it. In high energy quantum physics, it leads to the introduction of a Lorentzian renormalization group, in which the Planck length is reinterpreted as a lowest, unpassable scale, invariant under dilatations. These methods are successively applied to two problems: in quantum mechanics, that of the mass spectrum of elementary particles; in chaotic dynamics, that of the distribution of planets in the Solar System.

On biofouling of microplastic particles of different shapes - some mathematics

NASA Astrophysics Data System (ADS)

Bagaeva, Margarita; Chubarenko, Irina

2016-04-01

Transport of microplastic particles in marine environment is difficult to quantify because their physical properties may vary with time. We made an attempt to analyse the behaviour of slightly buoyant particles (e.g., polyethylene, polypropylene), most critical process for which is their fouling: it leads to an increase in the mean particle density and its sinking. Fouling covers the surface of a relatively light particle by a denser growing film; thus, the rate of increase in the total mass is directly proportional to the surface area, and the faster the fouling process is - the sooner the mean particle density reaches the water density; the particle begins sinking, leaves the surface layer with stronger currents and can no longer be transported too far. A simplified model of biofouling in marine environment of a slightly buoyant microplastics (ρp < ρw) is applied to particles of different shapes - spheres, films and fibres. It is supposed that the thickness of biofouling cover (of density ρb > ρw) increases with time at constant rate, and thus it can be considered as time. Geometrical considerations link surface area of particles of different shapes with time rate of increase in its mass due to fouling up to the water density. Geometrical calculations demonstrate that, for the same mass of plastic material, many small particles have larger surface area than one single large particle, and this way - macroplastics will stay longer at the water surface than microplastics. For spherical particles, the time of fouling up to the water density is directly proportional to the radius of a sphere: τsink ˜ R0/ 3n, where n = R0/ R, i.e., if the particle of radius R0reaches the water density in time τsink, the particle of radius R0/3 requires only τsink/9. Spherical shape has (for the given mass m0) the minimum surface area among all other possible shapes in 3-d space. The calculations performed for the same mass m0 have shown that the ratio of surface areas of a sphere (diameter 5 mm), a film (thickness of 15-30 microns) and a fibre (diameter of 30-100 microns) is about 1 / (50- 100) / (30-110) and thus, fibres appear to have the largest surface area for the given mass, immediately followed by films. Correspondingly, time of fouling up to sinking is of the same order of magnitude for films and fibres, and almost two orders of magnitude larger for spherical particles (of the same mass m0). More generally speaking, time of fouling is linearly dependent on the characteristic length scale of a particle (radius of sphere, thickness of the film, or radius of a fibre): the smaller the scale of the particle is - the faster it is fouled up to the water density. The conclusions are important for proper physical setting of the problem of microplastics transport in marine environment and for developing of physically-based parameterisations of microplastics particles properties in numerical models. The investigations are supported by Russian Science Foundation, project number 15-17-10020.

Real-time monitoring of particles, PAH, and CO in an occupied townhouse.

PubMed

Wallace, L

2000-01-01

Beginning in October 1996, indoor and sometimes outdoor air at an occupied house in a suburban area of Virginia has been monitored continuously for particles, PAH, and CO. Two Climet monitors have been used to count particles in six size ranges between 0.3 and > 10 microns, with 1-minute averages being collected every 5 minutes. Two Ecochem PAH monitors have been used to sample for particle-bound PAHs once every minute. Also, two Langan CO monitor-data loggers have measured CO once each minute while logging the PAH data. Two Aethalometers measure black carbon. A single Scanning Mobility Particle Sizer (SMPS) measures ultrafine particles. The pairs of monitors are set up either to provide an indoor/outdoor or an upstairs office/downstairs kitchen comparison. Air exchange is occasionally measured using a Bruel & Kjaer 1302 SF6 monitor, as a parameter necessary for estimating deposition rates for particles and PAH. Results from the first 16 months of monitoring (approximately 10 M observations) include: neighborhood woodburning and morning rush hour traffic are the most important sources of PAH and black carbon outdoors; candles, matches, incense, and frying, sauteeing, broiling, deep-frying, and stir-frying are additional important indoor sources of PM. One citronella candle was an extremely powerful PAH source. Neither woodburning nor vehicles appears to be an important source of particles indoors, but frying, grilling, and sauteeing are extremely strong indoor sources, together with combustion events such as use of matches and candles. Physical movement was an important source of coarse but not fine particles. Use of the gas stove for extended periods of time led to increased CO concentrations--vehicles and woodburning were relatively minor sources in comparison. The gas oven, gas burners, and electric toaster oven were important sources of ultrafine particles (< 0.1 micron). A source-proximity effect was noted with the kitchen monitor reading two to five times higher than the upstairs monitor for particles from kitchen events, while the upstairs monitor often read higher than the kitchen monitor for events caused by physical activity alone.

Lattice QCD and physics beyond the Standar Model: an experimentalist perspective

NASA Astrophysics Data System (ADS)

Artuso, Marina

2017-01-01

The new frontier in elementary particle physics is to find evidence for new physics that may lead to a deeper understanding of observations such as the baryon-antibaryon asymmetry of the universe, mass hierarchy, dark matter, or dark energy to name a few. Flavor physics provides a wealth of opportunities to find such signatures, and a vast body of data taken at e+e- b-factories and at hadron machines has provided valuable information, and a few tantalizing ``tensions'' with respect to the Standard Model predictions. While the window for new physics is still open, the chance that its manifestations will be subtle is very real. A vibrant experimental program is ongoing, and significant upgrades, such as the upgraded LHCb experiment at LHC and Belle 2 at KEKb, are imminent. One of the challenges in extracting new physics from flavor physics data is the need to relate observed hadron decays to fundamental particles and interactions. The continuous improvement of Lattice QCD predictions is a key element to achieve success in this quest. Improvements in algorithms and hardware have led to predictions of increasing precision on several fundamental matrix elements, and the continuous breaking of new grounds, thus allowing a broader spectrum of measurements to become relevant to this quest. An important aspect of the experiment-lattice synergy is a comparison between lattice predictions with experiment for a variety of hadronic quantities. This talk summarizes current synergies between lattice QCD theory and flavor physics experiments, and gives some highlights of expectations from future upgrades. this work was supported by NSF.

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.

Unscrambling the Omlette: a New Bubble and Crystal Clustering Mechanism in Chaotically Mixed Magma Flows

NASA Astrophysics Data System (ADS)

Robertson, J.; Metcalfe, G.; Wang, S.; Barnes, S. J.

2014-12-01

The concentration of bubbles, crystals or droplets into small volumes of magma is a key trigger for many interesting magmatic processes. For example, gas slugs driving Strombolian eruptions form from the coalesence of exsolved bubbles within a volcanic conduit, while Ni-Cu-PGE magmatic sulfide deposits require a concentration of dense sulfide droplets from a large volume of magma to form a massive ore body. However the physical mechanism for this clustering remains unresolved - especially since small particles in active magma flows are expected to mostly track flow streamlines rather than clustering. We have uncovered a previously unreported clustering mechanism which is applicable to magmatic flows. This mechanism involves the interaction of particles with two kinds of chaotic flow structure: (a) high-strain regions within the well-mixed chaotic zones of the flow, and (b) unmixed islands of stability within the chaotic flow, known as Kolmogorov-Arnold-Moser (KAM) regions. The first figure shows the difference between chaotic and KAM regions in a chaotic laminar pipe flow. Trapping occurs when particles are scattered from high-strain regions in the chaotic zones and become trapped in the KAM regions, leading to a rapid concentration of particles relative to their original distribution (shown in the second series of figures). Using a combination of these analogue experiments and theoretical analysis we outline the conditions under which this clustering process can occur. We examine the onset of secondary density-related instabilities and the effects of increased particle-particle interaction within the clustered particles, and highlight the impact of particle clustering on the dynamics of magma ascent and emplacement.

Attrition-enhanced sulfur capture by limestone particles in fluidized beds

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

Saastamoinen, J.J.; Shimizu, T.

2007-02-14

Sulfur capture by limestone particles in fluidized beds is a well-established technology. The underlying chemical and physical phenomena of the process have been extensively studied and modeled. However, most of the studies have been focused on the relatively brief initial stage of the process, which extends from a few minutes to hours, yet the residence time of the particles in the boiler is much longer. Following the initial stage, a dense product layer will be formed on the particle surface, which decreases the rate of sulfur capture and the degree of utilization of the sorbent. Attrition can enhance sulfur capturemore » by removing this layer. A particle model for sulfur capture has been incorporated with an attrition model. After the initial stage, the rate of sulfur capture stabilizes, so that attrition removes the surface at the same rate as diffusion and chemical reaction produces new product in a thin surface layer of a particle. An analytical solution for the conversion of particles for this regime is presented. The solution includes the effects of the attrition rate, diffusion, chemical kinetics, pressure, and SO{sub 2} concentration, relative to conversion-dependent diffusivity and the rate of chemical reaction. The particle model results in models that describe the conversion of limestone in both fly ash and bottom ash. These are incorporated with the residence time (or reactor) models to calculate the average conversion of the limestone in fly ash and bottom ash, as well as the efficiency of sulfur capture. Data from a large-scale pressurized fluidized bed are compared with the model results.« less

Space physics educational outreach

NASA Technical Reports Server (NTRS)

Copeland, Richard A.

1995-01-01

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

Cirrus cloud model parameterizations: Incorporating realistic ice particle generation

NASA Technical Reports Server (NTRS)

Sassen, Kenneth; Dodd, G. C.; Starr, David OC.

1990-01-01

Recent cirrus cloud modeling studies have involved the application of a time-dependent, two dimensional Eulerian model, with generalized cloud microphysical parameterizations drawn from experimental findings. For computing the ice versus vapor phase changes, the ice mass content is linked to the maintenance of a relative humidity with respect to ice (RHI) of 105 percent; ice growth occurs both with regard to the introduction of new particles and the growth of existing particles. In a simplified cloud model designed to investigate the basic role of various physical processes in the growth and maintenance of cirrus clouds, these parametric relations are justifiable. In comparison, the one dimensional cloud microphysical model recently applied to evaluating the nucleation and growth of ice crystals in cirrus clouds explicitly treated populations of haze and cloud droplets, and ice crystals. Although these two modeling approaches are clearly incompatible, the goal of the present numerical study is to develop a parametric treatment of new ice particle generation, on the basis of detailed microphysical model findings, for incorporation into improved cirrus growth models. For example, the relation between temperature and the relative humidity required to generate ice crystals from ammonium sulfate haze droplets, whose probability of freezing through the homogeneous nucleation mode are a combined function of time and droplet molality, volume, and temperature. As an example of this approach, the results of cloud microphysical simulations are presented showing the rather narrow domain in the temperature/humidity field where new ice crystals can be generated. The microphysical simulations point out the need for detailed CCN studies at cirrus altitudes and haze droplet measurements within cirrus clouds, but also suggest that a relatively simple treatment of ice particle generation, which includes cloud chemistry, can be incorporated into cirrus cloud growth.

Scaling relations of halo cores for self-interacting dark matter

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

Lin, Henry W.; Loeb, Abraham, E-mail: henrylin@college.harvard.edu, E-mail: aloeb@cfa.harvard.edu

2016-03-01

Using a simple analytic formalism, we demonstrate that significant dark matter self-interactions produce halo cores that obey scaling relations nearly independent of the underlying particle physics parameters such as the annihilation cross section and the mass of the dark matter particle. For dwarf galaxies, we predict that the core density ρ{sub c} and the core radius r{sub c} should obey ρ{sub c} r{sub c} ≈ 41 M{sub ⊙} pc{sup −2} with a weak mass dependence ∼ M{sup 0.2}. Remarkably, such a scaling relation has recently been empirically inferred. Scaling relations involving core mass, core radius, and core velocity dispersion are predicted and agree well with observationalmore » data. By calibrating against numerical simulations, we predict the scatter in these relations and find them to be in excellent agreement with existing data. Future observations can test our predictions for different halo masses and redshifts.« less

Biological Physics major as a means to stimulate an undergraduate physics program

NASA Astrophysics Data System (ADS)

Jaeger, Herbert; Eid, Khalid; Yarrison-Rice, Jan

2013-03-01

In an effort to stress the cross-disciplinary nature of modern physics we added a Biological Physics major. Drawing from coursework in physics, biology, chemistry, mathematics, and related disciplines, it combines a broad curriculum with physical and mathematical rigor in preparation for careers in biophysics, medical physics, and biomedical engineering. Biological Physics offers a new path of studies to a large pool of life science students. We hope to grow our physics majors from 70-80 to more than 100 students and boost our graduation rate from the mid-teens to the mid-twenties. The new major brought about a revision of our sophomore curriculum to make room for modern topics without sidelining fundamentals. As a result, we split our 1-semester long Contemporary Physics course (4 cr hrs) into a year-long sequence Contemporary Physics Foundations and Contemporary Physics Frontiers (both 3 cr hrs). Foundations starts with relativity, then focuses on 4 quantum mechanics topics: wells, spin 1/2, oscillators, and hydrogen. Throughout the course applications are woven in whenever the opportunity arises, e.g. magnetism and NMR with spin 1/2. The following semester Frontiers explores scientific principles and technological advances that make quantum science and resulting technologies different from the large scale. Frontiers covers enabling techniques from atomic, molecular, condensed matter, and particle physics, as well as advances in nanotechnology, quantum optics, and biophysics.

Cosmology of Universe Particles and Beyond

NASA Astrophysics Data System (ADS)

Xu, Wei

2016-06-01

For the first time in history, all properties of cosmology particles are uncovered and described concisely and systematically, known as the elementary particles in contemporary physics.Aligning with the synthesis of the virtual and physical worlds in a hierarchical taxonomy of the universe, this theory refines the topology framework of cosmology, and presents a new perspective of the Yin Yang natural laws that, through the processes of creation and reproduction, the fundamental elements generate an infinite series of circular objects and a Yin Yang duality of dynamic fields that are sequenced and transformed states of matter between the virtual and physical worlds.Once virtual objects are transformed, they embody various enclaves of energy states, known as dark energy, quarks, leptons, bosons, protons, and neutrons, characterized by their incentive oscillations of timestate variables in a duality of virtual realities: energy and time, spin and charge, mass and space, symmetry and antisymmetry.As a consequence, it derives the fully-scaled quantum properties of physical particles in accordance with numerous historical experiments, and has overcome the limitations of uncertainty principle and the Standard Model, towards concisely exploring physical nature and beyond...

Precision Crystal Calorimeters in High Energy Physics

ScienceCinema

Ren-Yuan Zhu

2017-12-09

Precision crystal calorimeters traditionally play an important role in high energy physics experiments. In the last two decades, it faces a challenge to maintain its precision in a hostile radiation environment. This paper reviews the performance of crystal calorimeters constructed for high energy physics experiments and the progress achieved in understanding crystal’s radiation damage as well as in developing high quality scintillating crystals for particle physics. Potential applications of new generation scintillating crystals of high density and high light yield, such as LSO and LYSO, in particle physics experiments is also discussed.