Science.gov

Sample records for granularity scintillator-based hadron

  1. Prototype tests for a highly granular scintillator-based hadron calorimeter

    NASA Astrophysics Data System (ADS)

    Krüger, K.; CALICE Collaboration

    2015-02-01

    Within the CALICE collaboration, several concepts for the hadronic calorimeter of a future linear collider detector are studied. After having demonstrated the capabilities of the measurement methods in "physics prototypes", the focus now lies on improving their implementation in"technological prototypes", that are scalable to the full linear collider detector. The Analog Hadron Calorimeter (AHCAL) concept is a sampling calorimeter of tungsten or steel absorber plates and plastic scintillator tiles read out by silicon photomultipliers as active material. In the AHCAL technological prototype, the front-end chips are integrated into the active layers of the calorimeter and are designed for minimal power consumption. The versatile electronics allows the prototype to be equipped with different types of scintillator tiles and SiPMs. The current status of the AHCAL engineering prototype is shown and recent beam test measurements as well as plans for future hadron beam tests with a larger prototype will be discussed.

  2. Highly granular hadron calorimeter: software compensation and shower decomposition

    NASA Astrophysics Data System (ADS)

    Chadeeva, M.; CALICE Collaboration

    2016-02-01

    The highly granular analogue hadron calorimeter was developed and constructed by the CALICE collaboration. The active layers of the calorimeter are assembled from scintillator tiles with individual readout by silicon photomultipliers and are interleaved with absorber plates. The response and resolution of the calorimeter equipped with steel absorber was intensively tested in single particle beams. The application of software compensation techniques developed for the scintillator-steel prototype allows for reduction of the stochastic term of the single particle resolution from 58%/ √E/GeV to 45%/ √E/GeV. The detailed study and decomposition of the longitudinal and radial profiles of hadron-induced showers in the energy range from 10 to 80 GeV are presented and compared to GEANT4 simulations.

  3. Hadronic models validation in GEANT4 with CALICE highly granular calorimeters

    NASA Astrophysics Data System (ADS)

    Ramilli, Marco; CALICE Collaboration

    2012-12-01

    The CALICE collaboration has constructed highly granular hadronic and electromagnetic calorimeter prototypes to evaluate technologies for the use in detector systems at a future Linear Collider, and to validate hadronic shower models with unprecedented spatial segmentation. The electromagnetic calorimeter is a sampling structure of tungsten and silicon with 9720 readout channels. The hadron calorimeter uses 7608 small plastic scintillator cells individually read out with silicon photomultipliers. This high granularity opens up the possibility for precise three-dimensional shower reconstructions and for software compensation techniques to improve the energy resolution of the detector. We discuss the latest results on the studies of shower shapes and shower properties and the comparison to the latest developed GEANT4 models for hadronic showers. A satisfactory agreement at better than 5% is found between data and simulations for most of the investigated variables. We show that applying software compensation methods based on reconstructed clusters the energy resolution for hadrons improves by a factor of 15%. The next challenge for CALICE calorimeters will be to validate the 4th dimension of hadronic showers, namely their time evolution.

  4. Hadron shower decomposition in the highly granular CALICE analogue hadron calorimeter

    NASA Astrophysics Data System (ADS)

    Eigen, G.; Price, T.; Watson, N. K.; Marshall, J. S.; Thomson, M. A.; Ward, D. R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Dotti, A.; Folger, G.; Ivantchenko, V.; Ribon, A.; Uzhinskiy, V.; Hostachy, J.-Y.; Morin, L.; Brianne, E.; Ebrahimi, A.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Irles, A.; Krivan, F.; Krüger, K.; Kvasnicka, J.; Lu, S.; Lutz, B.; Morgunov, V.; Neubüser, C.; Provenza, A.; Reinecke, M.; Sefkow, F.; Schuwalow, S.; Tran, H. L.; Garutti, E.; Laurien, S.; Matysek, M.; Ramilli, M.; Schröder, S.; Briggl, K.; Eckert, P.; Munwes, Y.; Schultz-Coulon, H.-Ch.; Shen, W.; Stamen, R.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; van Doren, B.; Wilson, G. W.; Kawagoe, K.; Hirai, H.; Sudo, Y.; Suehara, T.; Sumida, H.; Takada, S.; Tomita, T.; Yoshioka, T.; Wing, M.; Bonnevaux, A.; Combaret, C.; Caponetto, L.; Grenier, G.; Han, R.; Ianigro, J. C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Steen, A.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Marin, J.; Puerta-Pelayo, J.; Verdugo, A.; Bobchenko, B.; Markin, O.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kirikova, N.; Kozlov, V.; Smirnov, P.; Soloviev, Y.; Besson, D.; Buzhan, P.; Chadeeva, M.; Danilov, M.; Drutskoy, A.; Ilyin, A.; Mironov, D.; Mizuk, R.; Popova, E.; Gabriel, M.; Goecke, P.; Kiesling, C.; van der Kolk, N.; Simon, F.; Szalay, M.; Bilokin, S.; Bonis, J.; Cornebise, P.; Pöschl, R.; Richard, F.; Thiebault, A.; Zerwas, D.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J.-C.; Cizel, J.-B.; Clerc, C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Magniette, F.; Mora de Freitas, P.; Musat, G.; Pavy, S.; Rubio-Roy, M.; Ruan, M.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; Raux, L.; Seguin-Moreau, N.; de la Taille, Ch.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Kotera, K.; Ono, H.; Takeshita, T.; Ieki, S.; Kamiya, Y.; Ootani, W.; Shibata, N.; Jeans, D.; Komamiya, S.; Nakanishi, H.

    2016-06-01

    The spatial development of hadronic showers in the CALICE scintillator-steel analogue hadron calorimeter is studied using test beam data collected at CERN and FNAL for single positive pions and protons with initial momenta in the range of 10–80 GeV/c. Both longitudinal and radial development of hadron showers are parametrised with two-component functions. The parametrisation is fit to test beam data and simulations using the QGSP_BERT and FTFP_BERT physics lists from GEANT4 version 9.6. The parameters extracted from data and simulated samples are compared for the two types of hadrons. The response to pions and the ratio of the non-electromagnetic to the electromagnetic calorimeter response, h/e, are estimated using the extrapolation and decomposition of the longitudinal profiles.

  5. Construction and commissioning of a technological prototype of a high-granularity semi-digital hadronic calorimeter

    NASA Astrophysics Data System (ADS)

    Baulieu, G.; Bedjidian, M.; Belkadhi, K.; Berenguer, J.; Boudry, V.; Calabria, P.; Callier, S.; Calvo Almillo, E.; Cap, S.; Caponetto, L.; Combaret, C.; Cornat, R.; Cortina Gil, E.; de Callatay, B.; Davin, F.; de la Taille, C.; Dellanegra, R.; Delaunay, D.; Doizon, F.; Dulucq, F.; Eynard, A.; Fouz, M.-C.; Gastaldi, F.; Germani, L.; Grenier, G.; Haddad, Y.; Han, R.; Ianigro, J.-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Manai, K.; Mannai, S.; Mathez, H.; Mirabito, L.; Prast, J.; Puerta Pelayo, J.; Ruan, M.; Schirra, F.; Seguin-Moreau, N.; Steen, A.; Tromeur, W.; Tytgat, M.; Vander Donckt, M.; Vouters, G.; Zaganidis, N.

    2015-10-01

    A large prototype of 1.3 m3 was designed and built as a demonstrator of the semi-digital hadronic calorimeter (SDHCAL) concept proposed for the future ILC experiments. The prototype is a sampling hadronic calorimeter of 48 units. Each unit is built of an active layer made of 1 m2 Glass Resistive Plate Chamber (GRPC) detector placed inside a cassette whose walls are made of stainless steel. The cassette contains also the electronics used to read out the GRPC detector. The lateral granularity of the active layer is provided by the electronics pick-up pads of 1 cm2 each. The cassettes are inserted into a self-supporting mechanical structure built also of stainless steel plates which, with the cassettes walls, play the role of the absorber. The prototype was designed to be very compact and important efforts were made to minimize the number of services cables to optimize the efficiency of the Particle Flow Algorithm techniques to be used in the future ILC experiments. The different components of the SDHCAL prototype were studied individually and strict criteria were applied for the final selection of these components. Basic calibration procedures were performed after the prototype assembling. The prototype is the first of a series of new-generation detectors equipped with a power-pulsing mode intended to reduce the power consumption of this highly granular detector. A dedicated acquisition system was developed to deal with the output of more than 440000 electronics channels in both trigger and triggerless modes. After its completion in 2011, the prototype was commissioned using cosmic rays and particles beams at CERN.

  6. Radioactive threat detection using scintillant-based detectors

    NASA Astrophysics Data System (ADS)

    Chalmers, Alex

    2004-09-01

    An update to the performance of AS&E's Radioactive Threat Detection sensor technology. A model is presented detailing the components of the scintillant-based RTD system employed in AS&E products aimed at detecting radiological WMD. An overview of recent improvements in the sensors, electrical subsystems and software algorithms are presented. The resulting improvements in performance are described and sample results shown from existing systems. Advanced and future capabilities are described with an assessment of their feasibility and their application to Homeland Defense.

  7. Studies of silicon photodetectors for scintillator-based Hadron Calorimetry at the International Linear Collider

    NASA Astrophysics Data System (ADS)

    Beznosko, D.; Blazey, G.; Chakraborty, D.; Dyshkant, A.; Francis, K.; Kubik, D.; Lima, J. G.; Rykalin, V.; Zutshi, V.

    2006-11-01

    We present results on the operation and performance characteristics of the Metal/Resistor/Semiconductor (MRS) photodiode. These include measurements of threshold characteristics, noise frequency, dependence of signal amplitude on the applied voltage and temperature, and stability as a function of time and radiation dose. The single photoelectron separation for this photosensor is demonstrated with a light-emitting diode. The response of the photodetector to light produced in scintillator is studied with cosmic ray muons and a 106Ru source. In addition, fiber-sensor alignment issues were evaluated. The results are promising and illustrate the potential use of MRS as photosensors in high energy physics detectors.

  8. Atmospheric Neutron Measurements using a Small Scintillator Based Detector

    NASA Astrophysics Data System (ADS)

    Kole, Merlin; Pearce, Mark; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Yanagida, Takayuki; Chauvin, Maxime; Mikhalev, Victor; Rydstrom, Stefan; Takahashi, Hiromitsu

    PoGOLino is a standalone scintillator-based neutron detector designed for balloon-borne missions. Its main purpose is to provide data of the neutron flux in 2 different energy ranges in the high altitude / high latitude region where the highest neutron flux in the atmosphere is found. Furthermore the influence of the Solar activity upon the neutron environment in this region is relatively strong. As a result both short and long term time fluctuations are strongest in this region. At high altitudes neutrons can form a source of background for balloon-borne scientific measurements. They can furthermore form a major source for single event upsets in electronics. A good understanding of the high altitude / high latitude neutron environment is therefore important. Measurements of the neutron environment in this region are however lacking. PoGOLino contains two 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillators used for neutron detection. The LiCAF crystals are sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. The veto system makes measurements of the neutron flux possible even in high radiation environments. One LiCAF detector is shielded with polyethylene while the second remains unshielded, making the detectors sensitive in different energy ranges. The choice of a scintillator crystals as the detection material ensures a high detection efficiency while keeping the instrument small, robust and light weight. The full standalone cylindrical instrument has a radius of 120 mm, a height of 670 mm and a total mass of 13 kg, making it suitable as a piggy back mission. PoGOLino was successfully launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A detailed description of the detector design is presented, along with results of of the flight. The neutron flux measured during flight is compared to predictions based

  9. Clustering of Hadronic Showers with a Structural Algorithm

    SciTech Connect

    Charles, M.J.; /SLAC

    2005-12-13

    The internal structure of hadronic showers can be resolved in a high-granularity calorimeter. This structure is described in terms of simple components and an algorithm for reconstruction of hadronic clusters using these components is presented. Results from applying this algorithm to simulated hadronic Z-pole events in the SiD concept are discussed.

  10. Hadron-hadron colliders

    SciTech Connect

    Month, M.; Weng, W.T.

    1983-06-21

    The objective is to investigate whether existing technology might be extrapolated to provide the conceptual framework for a major hadron-hadron collider facility for high energy physics experimentation for the remainder of this century. One contribution to this large effort is to formalize the methods and mathematical tools necessary. In this report, the main purpose is to introduce the student to basic design procedures. From these follow the fundamental characteristics of the facility: its performance capability, its size, and the nature and operating requirements on the accelerator components, and with this knowledge, we can determine the technology and resources needed to build the new facility.

  11. A plastic scintillator-based 2D thermal neutron mapping system for use in BNCT studies.

    PubMed

    Ghal-Eh, N; Green, S

    2016-06-01

    In this study, a scintillator-based measurement instrument is proposed which is capable of measuring a two-dimensional map of thermal neutrons within a phantom based on the detection of 2.22MeV gamma rays generated via nth+H→D+γ reaction. The proposed instrument locates around a small rectangular water phantom (14cm×15cm×20cm) used in Birmingham BNCT facility. The whole system has been simulated using MCNPX 2.6. The results confirm that the thermal flux peaks somewhere between 2cm and 4cm distance from the system entrance which is in agreement with previous studies. PMID:26986813

  12. Survey on granularity clustering.

    PubMed

    Ding, Shifei; Du, Mingjing; Zhu, Hong

    2015-12-01

    With the rapid development of uncertain artificial intelligent and the arrival of big data era, conventional clustering analysis and granular computing fail to satisfy the requirements of intelligent information processing in this new case. There is the essential relationship between granular computing and clustering analysis, so some researchers try to combine granular computing with clustering analysis. In the idea of granularity, the researchers expand the researches in clustering analysis and look for the best clustering results with the help of the basic theories and methods of granular computing. Granularity clustering method which is proposed and studied has attracted more and more attention. This paper firstly summarizes the background of granularity clustering and the intrinsic connection between granular computing and clustering analysis, and then mainly reviews the research status and various methods of granularity clustering. Finally, we analyze existing problem and propose further research. PMID:26557926

  13. Hadron interactions

    SciTech Connect

    K. Orginos

    2011-12-01

    In this talk I am reviewing recent calculations of properties of multi-hadron systems in lattice QCD. In particular, I am reviewing results of elastic scattering phase shifts in meson-meson, meson-baryon and baryon-baryon systems, as well as discussing results indicating possible existence of bound states in two baryon systems. Finally, calculations of properties of systems with more than two hadrons are presented.

  14. Granular temperature field of monodisperse granular flows

    NASA Astrophysics Data System (ADS)

    Gollin, Devis; Bowman, Elisabeth; Shepley, Paul

    2015-04-01

    For dry granular flows as well as solid-fluid mixtures such as debris avalanches, the momentum transfer is carried by frictional and collisional stresses. The latter may be described by the granular temperature, which provides a measure of the energy contained within the fluctuating nature of the granular motion. Thus, granular temperature can be used as a valuable means to infer the ability of a granular system to flow. Granular materials are known for the difficulties they pose in obtaining accurate microscale laboratory measurements. This is why many theories, such as the kinetic theory of granular gases, are primarily compared to numerical simulations. However, thanks to recent advancements in optical techniques along with high-speed recording systems, experimentalists are now able to obtain robust measurements of granular temperature. At present, the role of granular temperature in granular flows still entails conjecture. As a consequence, it is extremely important to provide experimental data against which theories and simulations can be judged. This investigation focuses on dry granular flows of sand and spherical beads performed on a simple inclined chute geometry. Fluctuation velocity, granular temperature and velocity patterns are obtained by means of particle image velocimetry (PIV). Flow behaviour is probed for different spatial (interrogation sizes) and temporal (frame rates) resolutions. Through the variation of these parameters an attempt to demonstrate the consistency of the degree of unsteadiness within the flow is made. In many studies a uniform stationary flow state is usually sought or preferably assumed for the simplicity it provides in the calculations. If one tries to measure microscale fields such as granular temperature, this assumption may be inappropriate. Thus, a proper definition of the flow regime should be made in order to estimate the correct flow properties. In addition, PIV analysis is compared against particle tracking velocimetry

  15. Scintillator based energetic ion loss diagnostic for the National Spherical Torus Experiment

    SciTech Connect

    Darrow, D. S.

    2008-02-15

    A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) [Synakowski et al., Nucl. Fusion 43, 1653 (2000)] to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss in several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.

  16. Light collection optimization in scintillator-based gamma-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Hull, G.; Du, S.; Niedermayr, T.; Payne, S.; Cherepy, N.; Drobshoff, A.; Fabris, L.

    2008-04-01

    Scintillator-based gamma-ray detectors are being actively pursued for homeland security applications. A key property of such detectors is their energy resolution which enables faster detection and more precise identification of gamma-ray sources. In order to obtain the best energy resolution with a given scintillator material, it is crucial to collect the largest fraction possible of the light emitted after gamma-ray absorption. Different techniques to maximize the light collection efficiency were investigated and tested experimentally. In particular, the effect of the scintillator geometry has been simulated with Detect2000. Also, a number of wrapping materials have been tested for their reflectivity and their performance in terms of improving the energy resolution in a BGO-based gamma-ray detector. The best results were obtained with a tapered cylinder geometry and the GORE DRP tape.

  17. Near midplane scintillator-based fast ion loss detector on DIII-D

    SciTech Connect

    Chen, X.; Heidbrink, W. W.; Fisher, R. K.; Pace, D. C.; Chavez, J. A.; Van Zeeland, M. A.; Garcia-Munoz, M.

    2012-10-15

    A new scintillator-based fast-ion loss detector (FILD) installed near the outer midplane of the plasma has been commissioned on DIII-D. This detector successfully measures coherent fast ion losses produced by fast-ion driven instabilities ({<=}500 kHz). Combined with the first FILD at {approx}45 Degree-Sign below the outer midplane [R. K. Fisher, et al., Rev. Sci. Instrum. 81, 10D307 (2010)], the two-detector system measures poloidal variation of losses. The phase space sensitivity of the new detector (gyroradius r{sub L}{approx}[1.5-8] cm and pitch angle {alpha}{approx}[35 Degree-Sign -85 Degree-Sign ]) is calibrated using neutral beam first orbit loss measurements. Since fast ion losses are localized poloidally, having two FILDs at different poloidal locations allows for the study of losses over a wider range of plasma shapes and types of loss orbits.

  18. Scintillator Based Energetic Ion Loss Diagnostic for the National Spherical Torus Experiment

    SciTech Connect

    D.S. Darrow

    2007-07-02

    A scintillator based energetic ion loss detector has been built and installed on the National Spherical Torus Experiment (NSTX) to measure the loss of neutral beam ions. The detector is able to resolve the pitch angle and gyroradius of the lost energetic ions. It has a wide acceptance range in pitch angle and energy, and is able to resolve the full, one-half, and one-third energy components of the 80 keV D neutral beams up to the maximum toroidal magnetic field of NSTX. Multiple Faraday cups have been embedded behind the scintillator to allow easy absolute calibration of the diagnostic and to measure the energetic ion loss to several ranges of pitch angle with good time resolution. Several small, vacuum compatible lamps allow simple calibration of the scintillator position within the field of view of the diagnostic's video camera.

  19. Scintillator-based diagnostic for fast ion loss measurements on DIII-D.

    PubMed

    Fisher, R K; Pace, D C; García-Muñoz, M; Heidbrink, W W; Muscatello, C M; Van Zeeland, M A; Zhu, Y B

    2010-10-01

    A new scintillator-based fast ion loss detector has been installed on DIII-D with the time response (>100 kHz) needed to study energetic ion losses induced by Alfvén eigenmodes and other MHD instabilities. Based on the design used on ASDEX Upgrade, the diagnostic measures the pitch angle and gyroradius of ion losses based on the position of the ions striking the two-dimensional scintillator. For fast time response measurements, a beam splitter and fiberoptics couple a portion of the scintillator light to a photomultiplier. Reverse orbit following techniques trace the lost ions to their possible origin within the plasma. Initial DIII-D results showing prompt losses and energetic ion loss due to MHD instabilities are discussed. PMID:21033833

  20. Wet granular materials

    NASA Astrophysics Data System (ADS)

    Mitarai, Namiko; Nori, Franco

    2006-04-01

    Most studies on granular physics have focused on dry granular media, with no liquids between the grains. However, in geology and many real world applications (e.g. food processing, pharmaceuticals, ceramics, civil engineering, construction, and many industrial applications), liquid is present between the grains. This produces inter-grain cohesion and drastically modifies the mechanical properties of the granular media (e.g. the surface angle can be larger than 90 degrees). Here we present a review of the mechanical properties of wet granular media, with particular emphasis on the effect of cohesion. We also list several open problems that might motivate future studies in this exciting but mostly unexplored field.

  1. Hadron spectroscopy

    SciTech Connect

    Cooper, S.

    1985-10-01

    Heavy quark systems and glueball candidates, the particles which are relevant to testing QCD, are discussed. The review begins with the heaviest spectroscopically observed quarks, the b anti-b bound states, including the chi state masses, spins, and hadronic widths and the non-relativistic potential models. Also, P states of c anti-c are mentioned. Other heavy states are also discussed in which heavy quarks combine with lighter ones. The gluonium candidates iota(1460), theta(1700), and g/sub T/(2200) are then covered. The very lightest mesons, pi-neutral and eta, are discussed. 133 refs., 24 figs., 16 tabs. (LEW)

  2. On granular elasticity

    PubMed Central

    Sun, Qicheng; Jin, Feng; Wang, Guangqian; Song, Shixiong; Zhang, Guohua

    2015-01-01

    Mesoscopic structures form in dense granular materials due to the self-organisation of the constituent particles. These structures have internal structural degrees of freedom in addition to the translational degree of freedom. The resultant granular elasticity, which exhibits intrinsic variations and inevitable relaxation, is a key quantity that accounts for macroscopic solid- or fluid-like properties and the transitions between them. In this work, we propose a potential energy landscape (PEL) with local stable basins and low elastic energy barriers to analyse the nature of granular elasticity. A function for the elastic energy density is proposed for stable states and is further calibrated with ultrasonic measurements. Fluctuations in the elastic energy due to the evolution of internal structures are proposed to describe a so-called configuration temperature Tc as a counterpart of the classical kinetic granular temperature Tk that is attributed to the translational degrees of freedom. The two granular temperatures are chosen as the state variables, and a fundamental equation is established to develop non-equilibrium thermodynamics for granular materials. Due to the relatively low elastic energy barrier in the PEL, granular elasticity relaxes more under common mechanical loadings, and a simple model based on mean-field theory is developed to account for this behaviour. PMID:25951049

  3. Granular flow: Dry and wet

    NASA Astrophysics Data System (ADS)

    Mitarai, N.; Nakanishi, H.

    2012-04-01

    Granular material is a collection of macroscopic particles that are visible with naked eyes. The non-equilibrium nature of the granular materials makes their rheology quite different from that of molecular systems. In this minireview, we present the unique features of granular materials focusing on the shear flow of dry granular materials and granule-liquid mixture.

  4. Gravity and Granular Materials

    NASA Technical Reports Server (NTRS)

    Behringer, R. P.; Hovell, Daniel; Kondic, Lou; Tennakoon, Sarath; Veje, Christian

    1999-01-01

    We describe experiments that probe a number of different types of granular flow where either gravity is effectively eliminated or it is modulated in time. These experiments include the shaking of granular materials both vertically and horizontally, and the shearing of a 2D granular material. For the shaken system, we identify interesting dynamical phenomena and relate them to standard simple friction models. An interesting application of this set of experiments is to the mixing of dissimilar materials. For the sheared system we identify a new kind of dynamical phase transition.

  5. Dynamics of Granular Materials

    NASA Technical Reports Server (NTRS)

    Behringer, Robert P.

    1996-01-01

    Granular materials exhibit a rich variety of dynamical behavior, much of which is poorly understood. Fractal-like stress chains, convection, a variety of wave dynamics, including waves which resemble capillary waves, l/f noise, and fractional Brownian motion provide examples. Work beginning at Duke will focus on gravity driven convection, mixing and gravitational collapse. Although granular materials consist of collections of interacting particles, there are important differences between the dynamics of a collections of grains and the dynamics of a collections of molecules. In particular, the ergodic hypothesis is generally invalid for granular materials, so that ordinary statistical physics does not apply. In the absence of a steady energy input, granular materials undergo a rapid collapse which is strongly influenced by the presence of gravity. Fluctuations on laboratory scales in such quantities as the stress can be very large-as much as an order of magnitude greater than the mean.

  6. Vibrheology of Granular Matter

    NASA Astrophysics Data System (ADS)

    Dijksman, Joshua; Wortel, Geert; van Hecke, Martin

    2009-03-01

    We show how weak agitations substantially modify the rheology of granular materials. We experimentally probe dry granular flows in a weakly vibrated split bottom shear cell -- the weak vibrations act as the agitation source. By tuning the applied stress and vibration strength, and monitoring the resulting strain, we uncover a rich phase diagram in which non-trivial transitions separate a jammed phase, a creep flow case, and a steady flow case.

  7. Advanced Scintillator-Based Compton Telescope for Solar Flare Gamma-Ray Measurements

    NASA Astrophysics Data System (ADS)

    Ryan, James Michael; Bloser, Peter; McConnell, Mark; Legere, Jason; Bancroft, Christopher; Murphy, Ronald; de Nolfo, Georgia

    2015-04-01

    A major goal of future Solar and Heliospheric Physics missions is the understanding of the particle acceleration processes taking place on the Sun. Achieving this understanding will require detailed study of the gamma-ray emission lines generated by accelerated ions in solar flares. Specifically, it will be necessary to study gamma-ray line ratios over a wide range of flare intensities, down to small C-class flares. Making such measurements over such a wide dynamic range, however, is a serious challenge to gamma-ray instrumentation, which must deal with large backgrounds for faint flares and huge counting rates for bright flares. A fast scintillator-based Compton telescope is a promising solution to this instrumentation challenge. The sensitivity of Compton telescopes to solar flare gamma rays has already been demonstrated by COMPTEL, which was able to detect nuclear emission from a C4 flare, the faintest such detection to date. Modern fast scintillators, such as LaBr3, and CeBr3, are efficient at stopping MeV gamma rays, have sufficient energy resolution (4% or better above 0.5 MeV) to resolve nuclear lines, and are fast enough (~15 ns decay times) to record at very high rates. When configured as a Compton telescope in combination with a modern organic scintillator, such as p-terphenyl, sub-nanosecond coincidence resolving time allows dramatic suppression of background via time-of-flight (ToF) measurements, allowing both faint and bright gamma-ray line flares to be measured. The use of modern light readout devices, such as silicon photomultipliers (SiPMs), eliminates passive mass and permits a more compact, efficient instrument. We have flown a prototype Compton telescope using modern fast scintillators with SiPM readouts on a balloon test flight, achieving good ToF and spectroscopy performance. A larger balloon-borne instrument is currently in development. We present our test results and estimates of the solar flare sensitivity of a possible full-scale instrument

  8. High energy hadron-hadron collisions

    SciTech Connect

    Chou, T.T.

    1991-12-01

    Results of a study on high energy collision with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) the e{sup +}e{sup {minus}} annihilation. More recent studies are highlighted below. For elastic scattering, a modified form for the hadronic matter form factor of the proton was proposed which remains to be dipole in form but contains an energy-dependent range parameter. This new expression of the opacity function fits the elastic {bar p}p scattering very well from the ISR to S{bar p}pS energies. Extrapolation of this theory also yielded results in good agreement with the {bar p}p differential cross section measured at the Tevatron. For inelastic hadron-hadron collisions, we have made a systematic investigation of the single-particle momentum spectra in the entire S{bar p}pS energy region. Results are useful for the extrapolation of angular distribution to the higher SSC energies. In e{sup +}e{sup {minus}} annihilation, a detailed analysis of all available experimental multiplicity data from PETRA to LEP energies has been performed. We discovered that the cluster size of emitted hadrons increases steadily with energy and is close to 2 as we predicted.

  9. QCD in hadron-hadron collisions

    SciTech Connect

    Albrow, M.

    1997-03-01

    Quantum Chromodynamics provides a good description of many aspects of high energy hadron-hadron collisions, and this will be described, along with some aspects that are not yet understood in QCD. Topics include high E{sub T} jet production, direct photon, W, Z and heavy flavor production, rapidity gaps and hard diffraction.

  10. Modeling Granular Materials

    NASA Astrophysics Data System (ADS)

    Brackbill, J. U.

    2000-11-01

    Granular materials are often cited as examples of systems with complex and unusual properties. Much of this complexity is captured by computational models in which the actual material properties of individual grains are idealized and simplified. Because material properties can be important under extreme conditions, we consider assemblies of grains with more realistic properties. Our model grains may deform, their resulting stresses are computed from elastic / plastic constitutive models, and their interactions with each other include Coulomb friction and bonding. Our model equations are solved using a particle-in-cell (PIC) method, which combines a Lagrangian representation of the materials with an adaptive grid [1]. Our contact model between grains is linear in the number of grains, and we model assemblies with statistically significant numbers of grains. With our model, we have studied the response of dense granular material to shear, with especial attention to the probability density function governing the volume distribution of stress for mono- and poly-disperse samples, circular and polygonal grains, and various values of microscopic friction coefficients, yield stresses, and packing fractions [2]. Remarkably, PDF's are similar in form for all cases simulated, and similar to those observed in experiments with granular materials under both compression and shear. Namely, the simulations yield an exponential probability of large stresses above the mean, and there is a finite chance that a few grains in a large assembly are subjected to extreme stresses at any given time, even at low strain rates. For energetic materials, such as explosives, this is a signficant finding. We have also studied the relationship between distributions of boundary tractions and volume distributions of stress. The ratio of normal and tangential components of traction on the boundary defines a bulk frictional response, which we find increases with the inter-granular friction coefficient

  11. High energy hadron-hadron collisions

    SciTech Connect

    Chou, T.T.

    1990-11-01

    Results of a study on high energy collision with the geometrical model are summarized in three parts: (i) the elastic hadron-hadron collision, (ii) the inelastic hadron-hadron collision, and (iii) the e{sup +}e{sup {minus}} annihilation. For elastic collisions, a simple expression for the proton matter distribution is proposed which fits well the elastic {bar p}p scattering from ISR to S{bar p}pS energies within the geometrical model. The proton form factor is of the dipole form with an energy-dependent range parameter. The {bar p}p elastic differential cross section at Tevatron energies obtained by extrapolation is in good agreement with experiments. For multiparticle emission processes a unified physical picture for hadron-hadron and e{sup +}e{sup {minus}} collisions was proposed. A number of predictions were made, including the one that KNO-scaling does not obtain for e{sup +}e{sup {minus}} two-jet events. An extension of the considerations within the geometrical model led to a theory of the momentum distributions of the outgoing particles which are found in good agreement with current experimental data. Extrapolations of results to higher energies have been made. The cluster size of hadrons produced in e{sup +}e{sup {minus}} annihilation is found to increase slowly with energy.

  12. Granular convection in microgravity.

    PubMed

    Murdoch, N; Rozitis, B; Nordstrom, K; Green, S F; Michel, P; de Lophem, T-L; Losert, W

    2013-01-01

    We investigate the role of gravity on convection in a dense granular shear flow. Using a microgravity-modified Taylor-Couette shear cell under the conditions of parabolic flight microgravity, we demonstrate experimentally that secondary, convective-like flows in a sheared granular material are close to zero in microgravity and enhanced under high-gravity conditions, though the primary flow fields are unaffected by gravity. We suggest that gravity tunes the frictional particle-particle and particle-wall interactions, which have been proposed to drive the secondary flow. In addition, the degree of plastic deformation increases with increasing gravitational forces, supporting the notion that friction is the ultimate cause. PMID:23383851

  13. A Chiral Granular Gas

    NASA Astrophysics Data System (ADS)

    Tsai, J.-C.; Ye, Fangfu; Rodriguez, Juan; Gollub, J. P.; Lubensky, T. C.

    2005-05-01

    Inspired by rattleback toys, we created small chiral wires that rotate in a preferred direction on a vertically oscillating platform and quantified their motion with experiment and simulation. We demonstrate experimentally that angular momentum of rotation about particle centers of mass is converted to collective angular momentum of center-of-mass motion in a granular gas of these wires, and we introduce a continuum model that explains our observations.

  14. A chiral granular gas.

    PubMed

    Tsai, J-C; Ye, Fangfu; Rodriguez, Juan; Gollub, J P; Lubensky, T C

    2005-06-01

    Inspired by rattleback toys, we created small chiral wires that rotate in a preferred direction on a vertically oscillating platform and quantified their motion with experiment and simulation. We demonstrate experimentally that angular momentum of rotation about particle centers of mass is converted to collective angular momentum of center-of-mass motion in a granular gas of these wires, and we introduce a continuum model that explains our observations. PMID:16090323

  15. Spatiotemporally resolved granular acoustics

    NASA Astrophysics Data System (ADS)

    Owens, Eli; Daniels, Karen

    2011-03-01

    Acoustic techniques provide a non-invasive method of characterizing granular material properties; however, there are many challenges in formulating accurate models of sound propagation due to the inherently heterogeneous nature of granular materials. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of the amplitude of the acoustic wave. We observe that the average wave amplitude is largest within particles experiencing the largest forces. The force-dependence of this amplitude is in qualitative agreement with a simple Hertzian-like model for contact area. In addition, we investigate the power spectrum of the propagating signal using the piezoelectric sensors. For a Gaussian wave packet input, we observe a broad spectrum of transmitted frequencies below the driving frequency, and we quantify the characteristic frequencies and corresponding length scales of our material as the system pressure is varied.

  16. Hadron Physics at FAIR

    SciTech Connect

    Wiedner, Ulrich

    2011-10-24

    The new FAIR facility in Darmstadt has a broad program in the field of hadron and nuclear physics utilizing ion beams with unprecedented intensity and accuracy. The hadron physics program centers around the the high-energy storage ring HESR for antiprotons and the PANDA experiment that is integrated in it. The physics program includes among others topics like hadron spectroscopy in the charmonium mass region and below, hyperon physics, electromagnetic processes and charm in nuclei.

  17. Holographic model of hadronization.

    PubMed

    Evans, Nick; Tedder, Andrew

    2008-04-25

    We study hadronization of the final state in a particle-antiparticle annihilation using a holographic gravity dual description of QCD. At the point of hadronization we match the events to a simple (Gaussian) energy distribution in the five dimensional theory. The final state multiplicities are then modeled by calculating the overlap between the Gaussian and a set of functions in the fifth dimension which represent each hadron. We compare our results to those measured in e(+)e(-) collisions. Hadron production numbers over a range of 4 orders of magnitude are reproduced well. PMID:18518189

  18. Holographic Model of Hadronization

    SciTech Connect

    Evans, Nick; Tedder, Andrew

    2008-04-25

    We study hadronization of the final state in a particle-antiparticle annihilation using a holographic gravity dual description of QCD. At the point of hadronization we match the events to a simple (Gaussian) energy distribution in the five dimensional theory. The final state multiplicities are then modeled by calculating the overlap between the Gaussian and a set of functions in the fifth dimension which represent each hadron. We compare our results to those measured in e{sup +}e{sup -} collisions. Hadron production numbers over a range of 4 orders of magnitude are reproduced well.

  19. Granular mechanics and rifting

    NASA Astrophysics Data System (ADS)

    Reber, Jacqueline E.; Hayman, Nicholas W.; Lavier, Luc L.

    2013-04-01

    Numerical models have proved useful in the interpretation of seismic-scale images of rifted margins. In an effort to both test and further illuminate predictions of numerical models, workers have made some strides using map-scale field relations, microstructures, and strain analyses. Yet, fundamental predictions of modeling and tectonic restorations are not able to capture critical observations. For example, many models and interpretations call on continuous faults with restorable kinematic histories. In contrast, s-reflectors and other interpreted shear fabrics in the middle crust tend to be discontinuous and non-planar across a margin. Additionally, most rift-evolution models and interpretations call on end-member ductile flow laws over a range of mechanical and thermal conditions. In contrast, field observations have found that a range of "brittle" fault rocks (e.g., cataclasites and breccias) form in the deeper crust. Similarly, upper crustal materials in deep basins and fault zones can deform through both distributed and localized deformation. Altogether, there appears to be reason to bring a new perspective to aspects of the structural evolution of rifted margins. A granular mechanics approach to crustal deformation studies has several important strengths. Granular materials efficiently localize shear and exhibit a range of stick-slip behaviors, including quasi-viscous rheological responses. These behaviors emerge in discrete element models, analog-materials experiments, and natural and engineered systems regardless of the specific micromechanical flow law. Yet, strictly speaking, granular deformation occurs via failure of frictional contacts between elastic grains. Here, we explore how to relate granular-mechanics models to mesoscale (outcrop) structural evolution, in turn providing insight into basin- and margin- scale evolution. At this stage we are focusing on analog-materials experiments and micro-to-mesoscale observations linking theoretical predictions

  20. Subsurface Explosions in Granular Media

    NASA Astrophysics Data System (ADS)

    Lai, Shuyue; Houim, Ryan; Oran, Elaine

    2015-11-01

    Numerical simulations of coupled gas-granular flows are used to study properties of shock formation and propagation in media, such as sand or regolith on the moon, asteroids, or comets. The simulations were performed with a multidimensional fully compressible model, GRAF, which solves two sets of coupled Navier-Stokes equations, one for the gas and one for the granular medium. The specific case discussed here is for a subsurface explosion in a granular medium initiated by an equivalent of 200g of TNT in depths ranging from 0.1m to 3m. The background conditions of 100K, 10 Pa and loose initial particle volume fraction of 25% are consistent with an event on a comet. The initial blast creates a cavity as a granular shock expands outwards. Since the gas-phase shock propagates faster than the granular shock in loose, granular material, some gas and particles are ejected before the granular shock arrives. When the granular shock reaches the surface, a cap-like structure forms. This cap breaks and may fall back on the surface and in this process, relatively dense particle clusters form. At lower temperatures, the explosion timescales are increased and entrained particles are more densely packed.

  1. Heterogeneities in granular dynamics.

    PubMed

    Mehta, A; Barker, G C; Luck, J M

    2008-06-17

    The absence of Brownian motion in granular media is a source of much complexity, including the prevalence of heterogeneity, whether static or dynamic, within a given system. Such strong heterogeneities can exist as a function of depth in a box of grains; this is the system we study here. First, we present results from three-dimensional, cooperative and stochastic Monte Carlo shaking simulations of spheres on heterogeneous density fluctuations. Next, we juxtapose these with results obtained from a theoretical model of a column of grains under gravity; frustration via competing local fields is included in our model, whereas the effect of gravity is to slow down the dynamics of successively deeper layers. The combined conclusions suggest that the dynamics of a real granular column can be divided into different phases-ballistic, logarithmic, activated, and glassy-as a function of depth. The nature of the ground states and their retrieval (under zero-temperature dynamics) is analyzed; the glassy phase shows clear evidence of its intrinsic ("crystalline") states, which lie below a band of approximately degenerate ground states. In the other three phases, by contrast, the system jams into a state chosen randomly from this upper band of metastable states. PMID:18541918

  2. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak.

    PubMed

    García-Muñoz, M; Fahrbach, H-U; Zohm, H

    2009-05-01

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)]. PMID:19499603

  3. Development of a prototype scintillator-based portable γ-ray imager with coded aperture for intraoperative applications

    NASA Astrophysics Data System (ADS)

    Shimazoe, K.; Horiki, K.; Takahashi, H.

    2015-06-01

    In surgical treatment, the intraoperative detection of tissues is becoming important in order to localize malignant functionality. Visual inspection, which is mostly used, results in lower contrast whereas dual inspection with radio and optical sensors is more promising for accurate detection. A scintillator-based portable gamma-ray imager with a coded aperture has been designed and fabricated for exploring the use of coded-aperture imaging in intraoperative applications. The gamma-ray detector is composed of a 12×12 array of 2×2×10 mm3 Ce:GAGG (Ce doped Gd3Al2Ga3O12) crystals individually coupled to a 12×12 avalanche photodiode (APD) array. The APDs are individually read out using a custom-designed readout system using a time-over-threshold application-specific integrated circuit and field-programmable gate array. The coded aperture consists of M-array based holes of 0.5 mm size on a 0.3-mm thickness tungsten collimator. The imaging performance in the x, y, and z directions is measured and characterized for 122-keV gamma rays.

  4. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak

    SciTech Connect

    Garcia-Munoz, M.; Fahrbach, H.-U.; Zohm, H.; Collaboration: ASDEX Upgrade Team

    2009-05-15

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].

  5. Scintillator based detector for fast-ion losses induced by magnetohydrodynamic instabilities in the ASDEX upgrade tokamak

    NASA Astrophysics Data System (ADS)

    García-Muñoz, M.; Fahrbach, H.-U.; Zohm, H.; ASDEX Upgrade Team

    2009-05-01

    A scintillator based detector for fast-ion losses has been designed and installed on the ASDEX upgrade (AUG) tokamak [A. Herrmann and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. The detector resolves in time the energy and pitch angle of fast-ion losses induced by magnetohydrodynamics (MHD) fluctuations. The use of a novel scintillator material with a very short decay time and high quantum efficiency allows to identify the MHD fluctuations responsible for the ion losses through Fourier analysis. A Faraday cup (secondary scintillator plate) has been embedded behind the scintillator plate for an absolute calibration of the detector. The detector is mounted on a manipulator to vary its radial position with respect to the plasma. A thermocouple on the inner side of the graphite protection enables the safety search for the most adequate radial position. To align the scintillator light pattern with the light detectors a system composed by a lens and a vacuum-compatible halogen lamp has been allocated within the detector head. In this paper, the design of the scintillator probe, as well as the new technique used to analyze the data through spectrograms will be described. A last section is devoted to discuss the diagnosis prospects of this method for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)].

  6. Hadrons in Nuclei

    SciTech Connect

    Mosel, Ulrich

    2004-08-30

    Changes of hadronic properties in dense nuclear matter as predicted by theory have usually been investigated by means of relativistic heavy-ion reactions. In this talk I show that observable consequences of such changes can also be seen in more elementary reactions on nuclei. Particular emphasis is put on a discussion of photonuclear reactions; examples are the dilepton production at {approx_equal} 1 GeV and the hadron production in nuclei at 10-20 GeV photon energies. The observable effects are expected to be as large as in relativistic heavy-ion collisions and can be more directly related to the underlying hadronic changes.

  7. Swirling granular solidlike clusters

    NASA Astrophysics Data System (ADS)

    Scherer, Michael A.; Kötter, Karsten; Markus, Mario; Goles, Eric; Rehberg, Ingo

    2000-04-01

    Experiments and three-dimensional numerical simulations are presented to elucidate the dynamics of granular material in a cylindrical dish driven by a horizontal, periodic motion. The following phenomena are obtained both in the experiments and in the simulations: First, for large particle numbers N the particles describe hypocycloidal trajectories. In this state the particles are embedded in a solidlike cluster (``pancake'') which counter-rotates with respect to the external driving (reptation). Self-organization within the cluster occurs such that the probability distribution of the particles consists of concentric rings. Second, the system undergoes phase transitions. These can be identified by changes of the quantity dEkin/dN (Ekin is the mean kinetic energy) between zero (rotation), positive (reptation), and negative values (appearance of the totality of concentric rings).

  8. Granular Materials Research at NASA-Glenn

    NASA Technical Reports Server (NTRS)

    Agui, Juan H.; Daidzic, Nihad; Green, Robert D.; Nakagawa, Masami; Nayagam, Vedha; Rame, Enrique; Wilkinson, Allen

    2002-01-01

    This paper presents viewgraphs of granular materials research at NASA-Glenn. The topics include: 1) Impulse dispersion of a tapered granular chain; 2) High Speed Digital Images of Tapered Chain Dynamics; 3) Impulse Dispersion; 4) Three Dimensional Granular Bed Experimental Setup; 5) Magnetic Resonance Imaging of Fluid Flow in Porous Media; and 6) Net Charge on Granular Materials (NCharG).

  9. Congenital granular-cell myoblastoma.

    PubMed

    Cussen, L J; MacMahon, R A

    1975-04-01

    The clinical and pathologic features of congenital granular-cell myoblastoma in five infant girls are reported. One lesion, treated expectantly, progressively decreased in size and after 3 yr and 9 mo could not be detected, while two lesions which were imcompletely excised did not recur. It is suggested that congenital granular-cell myoblastoma is caused by an intrauterine stimulus, and that this stimulus may possible be production of estrogen by the fetus. Congential granular-cell myoblastoma should be treated expectantly or by limited excision, and has an excellent prognosis. PMID:164527

  10. Granular temperature profiles in three-dimensional vibrofluidized granular beds

    SciTech Connect

    Wildman, R. D.; Huntley, J. M.; Parker, D. J.

    2001-06-01

    The motion of grains in a three-dimensional vibrofluidized granular bed has been measured using the technique of positron emission particle tracking, to provide three-dimensional packing fraction and granular temperature distributions. The mean square fluctuation velocity about the mean was calculated through analysis of the short time mean squared displacement behavior, allowing measurement of the granular temperature at packing fractions of up to {eta}{similar_to}0.15. The scaling relationship between the granular temperature, the number of layers of grains, and the base velocity was determined. Deviations between the observed scaling exponents and those predicted by recent theories are attributed to the influence of dissipative grain-sidewall collisions.

  11. Topics in Hadronic Physics

    SciTech Connect

    Alfred Tang

    2002-08-01

    Hadron production cross sections are calculated in the perturbative QCD frame work. Parton distribution functions are obtained from a strip-soliton model. The fragmentation functions are derived from the Lund model of string breaking.

  12. Melting hadrons, boiling quarks

    NASA Astrophysics Data System (ADS)

    Rafelski, Johann

    2015-09-01

    In the context of the Hagedorn temperature half-centenary I describe our understanding of the hot phases of hadronic matter both below and above the Hagedorn temperature. The first part of the review addresses many frequently posed questions about properties of hadronic matter in different phases, phase transition and the exploration of quark-gluon plasma (QGP). The historical context of the discovery of QGP is shown and the role of strangeness and strange antibaryon signature of QGP illustrated. In the second part I discuss the corresponding theoretical ideas and show how experimental results can be used to describe the properties of QGP at hadronization. The material of this review is complemented by two early and unpublished reports containing the prediction of the different forms of hadron matter, and of the formation of QGP in relativistic heavy ion collisions, including the discussion of strangeness, and in particular strange antibaryon signature of QGP.

  13. Renormdynamics and Hadronization

    NASA Astrophysics Data System (ADS)

    Makhaldiani, Nugzar

    2016-01-01

    Independently radiating valence quarks and corresponding negative binomial distribution presents phenomenologically preferable mechanism of hadronization in multiparticle production processes. Main properties of the renormdynamics, corresponding motion equations and their solutions are considered.

  14. Jets in hadronic reactions

    SciTech Connect

    Paige, F.E.

    1983-01-01

    Recent experimental data on the properties of jets in hadronic reactions are reviewed and compared with theoretical expectations. Jets are clearly established as the dominant process for high E/sub T/ events in hadronic reactions. The cross section and the other properties of these events are in qualitative and even semiquantitative agreement with expectations based on perturbative QCD. However, we can not yet make precise tests of QCD, primarily because there are substantial uncertainties in the theoretical calculations. 45 references. (WHK)

  15. Hadron spectroscopy---Conclusions

    SciTech Connect

    Landua, R.

    1995-07-10

    The session on hadron spectroscopy covered a wide range of new results on the light and heavy meson spectrum. The discovery of three new scalar mesons at LEAR may be crucial for our understanding of the scalar nonet and the possible existence of exotic scalar states. An outlook on the prospects of hadron spectroscopy is given. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  16. Intermittency in dilute granular flows

    NASA Astrophysics Data System (ADS)

    Guo, Wenxuan; Zhang, Qiang; Wylie, Jonathan J.

    2016-07-01

    In this letter, we show that dilute granular systems can exhibit a type of intermittency that has no analogue in gas dynamics. We consider a simple system in which a very dilute set of granular particles falls under gravity through a nozzle. This setting is analogous to the classical problem of high-speed nozzle flow in the study of compressible gases. It is well known that very dilute granular systems exhibit behavior qualitatively similar to gases, and that gas flowing through a nozzle does not exhibit intermittency. Nevertheless, we show that the intermittency in dilute granular nozzle flows can occur and corresponds to complicated transitions between supersonic and subsonic regimes. We also provide detailed explanations of the mechanism underlying this phenomenon.

  17. Optimized Simulation of Granular Materials

    NASA Astrophysics Data System (ADS)

    Holladay, Seth

    Visual effects for film and animation often require simulated granular materials, such as sand, wheat, or dirt, to meet a director's needs. Simulating granular materials can be time consuming, in both computation and labor, as these particulate materials have complex behavior and an enormous amount of small-scale detail. Furthermore, a single cubic meter of granular material, where each grain is a cubic millimeter, would contain a billion granules, and simulating all such interacting granules would take an impractical amount of time for productions. This calls for a simplified model for granular materials that retains high surface detail and granular behavior yet requires significantly less computational time. Our proposed method simulates a minimal number of individual granules while retaining particulate detail on the surface by supporting surface particles with simplified interior granular models. We introduce a multi-state model where, depending on the material state of the interior granules, we replace interior granules with a simplified simulation model for the state they are in and automate the transitions between those states. The majority of simulation time can thus be focused on visible portions of the material, reducing the time spent on non-visible portions, while maintaining the appearance and behavior of the mass as a whole.

  18. Granular Superconductors and Gravity

    NASA Technical Reports Server (NTRS)

    Noever, David; Koczor, Ron

    1999-01-01

    As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (approx. 10(exp -6) g cu cm). Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating Type II, YBCO superconductor, with a relatively high percentage change (0.05-2.1%) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 104 was reported above a stationary (non-rotating) superconductor. In experiments using a sensitive gravimeter, bulk YBCO superconductors were stably levitated in a DC magnetic field and exposed without levitation to low-field strength AC magnetic fields. Changes in observed gravity signals were measured to be less than 2 parts in 108 of the normal gravitational acceleration. Given the high sensitivity of the test, future work will examine variants on the basic magnetic behavior of granular superconductors, with particular focus on quantifying their proposed importance to gravity.

  19. [Large granular lymphocyte leukemia].

    PubMed

    Lazaro, Estibaliz; Caubet, Olivier; Menard, Fanny; Pellegrin, Jean-Luc; Viallard, Jean-François

    2007-11-01

    Large granular lymphocyte (LGL) leukemia is a clonal proliferation of cytotoxic cells, either CD3(+) (T-cell) or CD3(-) (natural killer, or NK). Both subtypes can manifest as indolent or aggressive disorders. T-LGL leukemia is associated with cytopenias and autoimmune diseases and most often has an indolent course and good prognosis. Rheumatoid arthritis and Felty syndrome are frequent. NK-LGL leukemias can be more aggressive. LGL expansion is currently hypothesized to be a virus (Ebstein Barr or human T-cell leukemia viruses) antigen-driven T-cell response that involves disruption of apoptosis. The diagnosis of T-LGL is suggested by flow cytometry and confirmed by T-cell receptor gene rearrangement studies. Clonality is difficult to determine in NK-LGL but use of monoclonal antibodies specific for killer cell immunoglobulin-like receptor (KIR) has improved this process. Treatment is required when T-LGL leukemia is associated with recurrent infections secondary to chronic neutropenia. Long-lasting remission can be obtained with immunosuppressive treatments such as methotrexate, cyclophosphamide, and cyclosporine A. NK-LGL leukemias may be more aggressive and refractory to conventional therapy. PMID:17596907

  20. Structure of hadrons and hadronic matter. Proceedings.

    NASA Astrophysics Data System (ADS)

    Scholten, O.; Koch, J. H.

    The lectures at the summer school were focussed on the dynamics and structure of hadronic systems. This theme was examined from various perspectives. For nuclear matter close to normal densities and for relatively low excitation energies, a description in terms of nucleon degrees of freedom is appropriate. As the density increases, but in some case already under normal conditions, relativistic effects become important and a relativistic approach is necessary. For the description of heavy ion scattering at high energies or to understand the dynamics governing neutron stars, one must explicitly take into account also the non-nucleon degrees of freedom.

  1. Development of the scintillator-based probe for fast-ion losses in the HL-2A tokamak

    SciTech Connect

    Zhang, Y. P. Liu, Yi; Yuan, G. L.; Song, X. Y.; Yang, J. W.; Li, X.; Chen, W.; Li, Y.; Yan, L. W.; Song, X. M.; Yang, Q. W.; Duan, X. R.; Luo, X. B.; Liu, Y. Q.; Hua, Y.; Isobe, M.

    2014-05-15

    A new scintillator-based lost fast-ion probe (SLIP) has been developed and operated in the HL-2A tokamak [L. W. Yan, X. R. Duan, X. T. Ding, J. Q. Dong, Q. W. Yang, Yi Liu, X. L. Zou, D. Q. Liu, W. M. Xuan, L. Y. Chen, J. Rao, X. M. Song, Y. Huang, W. C. Mao, Q. M. Wang, Q. Li, Z. Cao, B. Li, J. Y. Cao, G. J. Lei, J. H. Zhang, X. D. Li, W. Chen, J. Chen, C. H. Cui, Z. Y. Cui, Z. C. Deng, Y. B. Dong, B. B. Feng, Q. D. Gao, X. Y. Han, W. Y. Hong, M. Huang, X. Q. Ji, Z. H. Kang, D. F. Kong, T. Lan, G. S. Li, H. J. Li, Qing Li, W. Li, Y. G. Li, A. D. Liu, Z. T. Liu, C. W. Luo, X. H. Mao, Y. D. Pan, J. F. Peng, Z. B. Shi, S. D. Song, X. Y. Song, H. J. Sun, A. K. Wang, M. X. Wang, Y. Q. Wang, W. W. Xiao, Y. F. Xie, L. H. Yao, D. L. Yu, B. S. Yuan, K. J. Zhao, G. W. Zhong, J. Zhou, J. C. Yan, C. X. Yu, C. H. Pan, Y. Liu, and the HL-2A Team , Nucl. Fusion 51, 094016 (2011)] to measure the losses of neutral beam ions. The design of the probe is based on the concept of the α-particle detectors on Tokamak Fusion Test Reactor (TFTR) using scintillator plates. The probe is capable of traveling across an equatorial plane port and sweeping the aperture angle rotationally with respect to the axis of the probe shaft by two step motors, in order to optimize the radial position and the collimator angle. The energy and the pitch angle of the lost fast ions can be simultaneously measured if the two-dimensional image of scintillation light intensity due to the impact of the lost fast ions is detected. Measurements of the fast-ion losses using the probe have been performed during HL-2A neutral beam injection discharges. The clear experimental evidence of enhanced losses of beam ions during disruptions has been obtained by means of the SLIP system. A detailed description of the probe system and the first experimental results are reported.

  2. Development of the scintillator-based probe for fast-ion losses in the HL-2A tokamak

    NASA Astrophysics Data System (ADS)

    Zhang, Y. P.; Liu, Yi; Luo, X. B.; Isobe, M.; Yuan, G. L.; Liu, Y. Q.; Hua, Y.; Song, X. Y.; Yang, J. W.; Li, X.; Chen, W.; Li, Y.; Yan, L. W.; Song, X. M.; Yang, Q. W.; Duan, X. R.

    2014-05-01

    A new scintillator-based lost fast-ion probe (SLIP) has been developed and operated in the HL-2A tokamak [L. W. Yan, X. R. Duan, X. T. Ding, J. Q. Dong, Q. W. Yang, Yi Liu, X. L. Zou, D. Q. Liu, W. M. Xuan, L. Y. Chen, J. Rao, X. M. Song, Y. Huang, W. C. Mao, Q. M. Wang, Q. Li, Z. Cao, B. Li, J. Y. Cao, G. J. Lei, J. H. Zhang, X. D. Li, W. Chen, J. Chen, C. H. Cui, Z. Y. Cui, Z. C. Deng, Y. B. Dong, B. B. Feng, Q. D. Gao, X. Y. Han, W. Y. Hong, M. Huang, X. Q. Ji, Z. H. Kang, D. F. Kong, T. Lan, G. S. Li, H. J. Li, Qing Li, W. Li, Y. G. Li, A. D. Liu, Z. T. Liu, C. W. Luo, X. H. Mao, Y. D. Pan, J. F. Peng, Z. B. Shi, S. D. Song, X. Y. Song, H. J. Sun, A. K. Wang, M. X. Wang, Y. Q. Wang, W. W. Xiao, Y. F. Xie, L. H. Yao, D. L. Yu, B. S. Yuan, K. J. Zhao, G. W. Zhong, J. Zhou, J. C. Yan, C. X. Yu, C. H. Pan, Y. Liu, and the HL-2A Team, Nucl. Fusion 51, 094016 (2011)] to measure the losses of neutral beam ions. The design of the probe is based on the concept of the α-particle detectors on Tokamak Fusion Test Reactor (TFTR) using scintillator plates. The probe is capable of traveling across an equatorial plane port and sweeping the aperture angle rotationally with respect to the axis of the probe shaft by two step motors, in order to optimize the radial position and the collimator angle. The energy and the pitch angle of the lost fast ions can be simultaneously measured if the two-dimensional image of scintillation light intensity due to the impact of the lost fast ions is detected. Measurements of the fast-ion losses using the probe have been performed during HL-2A neutral beam injection discharges. The clear experimental evidence of enhanced losses of beam ions during disruptions has been obtained by means of the SLIP system. A detailed description of the probe system and the first experimental results are reported.

  3. Development of the scintillator-based probe for fast-ion losses in the HL-2A tokamak.

    PubMed

    Zhang, Y P; Liu, Yi; Luo, X B; Isobe, M; Yuan, G L; Liu, Y Q; Hua, Y; Song, X Y; Yang, J W; Li, X; Chen, W; Li, Y; Yan, L W; Song, X M; Yang, Q W; Duan, X R

    2014-05-01

    A new scintillator-based lost fast-ion probe (SLIP) has been developed and operated in the HL-2A tokamak [L. W. Yan, X. R. Duan, X. T. Ding, J. Q. Dong, Q. W. Yang, Yi Liu, X. L. Zou, D. Q. Liu, W. M. Xuan, L. Y. Chen, J. Rao, X. M. Song, Y. Huang, W. C. Mao, Q. M. Wang, Q. Li, Z. Cao, B. Li, J. Y. Cao, G. J. Lei, J. H. Zhang, X. D. Li, W. Chen, J. Chen, C. H. Cui, Z. Y. Cui, Z. C. Deng, Y. B. Dong, B. B. Feng, Q. D. Gao, X. Y. Han, W. Y. Hong, M. Huang, X. Q. Ji, Z. H. Kang, D. F. Kong, T. Lan, G. S. Li, H. J. Li, Qing Li, W. Li, Y. G. Li, A. D. Liu, Z. T. Liu, C. W. Luo, X. H. Mao, Y. D. Pan, J. F. Peng, Z. B. Shi, S. D. Song, X. Y. Song, H. J. Sun, A. K. Wang, M. X. Wang, Y. Q. Wang, W. W. Xiao, Y. F. Xie, L. H. Yao, D. L. Yu, B. S. Yuan, K. J. Zhao, G. W. Zhong, J. Zhou, J. C. Yan, C. X. Yu, C. H. Pan, Y. Liu, and the HL-2A Team, Nucl. Fusion 51, 094016 (2011)] to measure the losses of neutral beam ions. The design of the probe is based on the concept of the α-particle detectors on Tokamak Fusion Test Reactor (TFTR) using scintillator plates. The probe is capable of traveling across an equatorial plane port and sweeping the aperture angle rotationally with respect to the axis of the probe shaft by two step motors, in order to optimize the radial position and the collimator angle. The energy and the pitch angle of the lost fast ions can be simultaneously measured if the two-dimensional image of scintillation light intensity due to the impact of the lost fast ions is detected. Measurements of the fast-ion losses using the probe have been performed during HL-2A neutral beam injection discharges. The clear experimental evidence of enhanced losses of beam ions during disruptions has been obtained by means of the SLIP system. A detailed description of the probe system and the first experimental results are reported. PMID:24880364

  4. Hadron Resonances from QCD

    NASA Astrophysics Data System (ADS)

    Dudek, Jozef J.

    2016-03-01

    I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study ππ elastic scattering, including the ρ resonance, as well as coupled-channel πK, ηK scattering. The very recent extension to the case where an external current acts is also presented, considering the reaction πγ* → ππ, from which the unstable ρ → πγ transition form factor is extracted. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  5. Aspects of hadron physics.

    SciTech Connect

    Bhagwat, M. S.; Hoell, A.; Roberts, C. D.; Wright, S. V.; Physics; Univ. Rostock

    2007-01-01

    Detailed investigations of the structure of hadrons are essential for understanding how matter is constructed from the quarks and gluons of Quantum chromodynamics (QCD), and amongst the questions posed to modern hadron physics, three stand out. What is the rigorous, quantitative mechanism responsible for confinement? What is the connection between confinement and dynamical chiral symmetry breaking? And are these phenomena together sufficient to explain the origin of more than 98% of the mass of the observable universe? Such questions may only be answered using the full machinery of nonperturbative relativistic quantum field theory. This contribution provides a perspective on progress toward answering these key questions. In so doing it will provide an overview of the contemporary application of Dyson-Schwinger equations in Hadron Physics, additional information on which may be found in Refs. [1, 2, 3, 4, 5, 6]. The presentation assumes that the reader is familiar with the concepts and notation of relativistic quantum mechanics, with the functional integral formulation of quantum field theory and with regularization and renormalization in its perturbative formulation. For these topics, in order of appearance, Refs. [7, 8, 9, 10] are useful. In addition, Chaps. 1 and 2 of Ref. [5] review the bulk of the necessary concepts. Hadron physics is a key part of the international effort in basic science. For example, in the USA we currently have the Thomas Jefferson National Accelerator Facility (JLab) and the Relativistic Heavy Ion Collider (RHIC) while in Europe hadron physics is studied at the Frascati National Laboratory and is an important part of a forthcoming pan-European initiative; namely, the Facility for Antiproton and Ion Research (FAIR) at GSI-Darmstadt. Progress in this field is gauged via the successful completion of precision measurements of fundamental properties of hadrons; e.g., the pion, proton and neutron, and simple nuclei, for comparison with

  6. High intensity hadron accelerators

    SciTech Connect

    Teng, L.C.

    1989-05-01

    This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics.

  7. Hadron Physics with Antiprotons

    SciTech Connect

    Wiedner, Ulrich

    2005-10-26

    The new FAIR facility which comes into operation at GSI in the upcoming years has a dedicated program of utilizing antiprotons for hadron physics. In particular, the planned PANDA experiment belongs to the group of core experiments at the new FAIR facility in Darmstadt/Germany. PANDA will be a universal detector to study the strong interaction by utilizing the annihilation process of antiprotons with protons and nuclear matter. The current paper gives an introduction into the hadron physics with antiprotons and part of the planned physics program with PANDA.

  8. Dynamic granularity of imaging systems

    NASA Astrophysics Data System (ADS)

    Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; Porter, John L.

    2015-11-01

    Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the "dynamic granularity" G dyn as a standardized, objective relation between a detector's spatial resolution (granularity) and dynamic range for complex imaging systems in a given environment rather than the widely found characterization of detectors such as cameras or films by themselves. This relation can partly be explained through consideration of the signal's photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging system's performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. This article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandia's Z-Backlighter facility.

  9. Silo collapse under granular discharge.

    PubMed

    Gutiérrez, G; Colonnello, C; Boltenhagen, P; Darias, J R; Peralta-Fabi, R; Brau, F; Clément, E

    2015-01-01

    We investigate, at a laboratory scale, the collapse of cylindrical shells of radius R and thickness t induced by a granular discharge. We measure the critical filling height for which the structure fails upon discharge. We observe that the silos sustain filling heights significantly above an estimation obtained by coupling standard shell-buckling and granular stress distribution theories. Two effects contribute to stabilize the structure: (i) below the critical filling height, a dynamical stabilization due to granular wall friction prevents the localized shell-buckling modes to grow irreversibly; (ii) above the critical filling height, collapse occurs before the downward sliding motion of the whole granular column sets in, such that only a partial friction mobilization is at play. However, we notice also that the critical filling height is reduced as the grain size d increases. The importance of grain size contribution is controlled by the ratio d/√[Rt]. We rationalize these antagonist effects with a novel fluid-structure theory both accounting for the actual status of granular friction at the wall and the inherent shell imperfections mediated by the grains. This theory yields new scaling predictions which are compared with the experimental results. PMID:25615503

  10. Granular fountains: Convection cascade in a compartmentalized granular gas

    NASA Astrophysics Data System (ADS)

    van der Meer, Devaraj; van der Weele, Ko; Reimann, Peter

    2006-06-01

    This paper extends the two-compartment granular fountain [D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse, Phys. Rev. Lett. 92, 184301 (2004)] to an arbitrary number of compartments: The tendency of a granular gas to form clusters is exploited to generate spontaneous convective currents, with particles going down in the well-filled compartments and going up in the diluted ones. We focus upon the bifurcation diagram of the general K -compartment system, which is constructed using a dynamical flux model and which proves to agree quantitatively with results from molecular dynamics simulations.

  11. Hadron Therapy for Cancer Treatment

    SciTech Connect

    Lennox, Arlene

    2003-09-10

    The biological and physical rationale for hadron therapy is well understood by the research community, but hadron therapy is not well established in mainstream medicine. This talk will describe the biological advantage of neutron therapy and the dose distribution advantage of proton therapy, followed by a discussion of the challenges to be met before hadron therapy can play a significant role in treating cancer. A proposal for a new research-oriented hadron clinic will be presented.

  12. Weibull model of multiplicity distribution in hadron-hadron collisions

    NASA Astrophysics Data System (ADS)

    Dash, Sadhana; Nandi, Basanta K.; Sett, Priyanka

    2016-06-01

    We introduce the use of the Weibull distribution as a simple parametrization of charged particle multiplicities in hadron-hadron collisions at all available energies, ranging from ISR energies to the most recent LHC energies. In statistics, the Weibull distribution has wide applicability in natural processes that involve fragmentation processes. This provides a natural connection to the available state-of-the-art models for multiparticle production in hadron-hadron collisions, which involve QCD parton fragmentation and hadronization. The Weibull distribution describes the multiplicity data at the most recent LHC energies better than the single negative binomial distribution.

  13. Interfacial Instability during Granular Erosion

    NASA Astrophysics Data System (ADS)

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-01

    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results.

  14. Granular Rayleigh-Taylor instability

    SciTech Connect

    Vinningland, Jan Ludvig; Johnsen, Oistein; Flekkoey, Eirik G.; Maaloey, Knut Joergen; Toussaint, Renaud

    2009-06-18

    A granular instability driven by gravity is studied experimentally and numerically. The instability arises as grains fall in a closed Hele-Shaw cell where a layer of dense granular material is positioned above a layer of air. The initially flat front defined by the grains subsequently develops into a pattern of falling granular fingers separated by rising bubbles of air. A transient coarsening of the front is observed right from the start by a finger merging process. The coarsening is later stabilized by new fingers growing from the center of the rising bubbles. The structures are quantified by means of Fourier analysis and quantitative agreement between experiment and computation is shown. This analysis also reveals scale invariance of the flow structures under overall change of spatial scale.

  15. Interfacial Instability during Granular Erosion.

    PubMed

    Lefebvre, Gautier; Merceron, Aymeric; Jop, Pierre

    2016-02-12

    The complex interplay between the topography and the erosion and deposition phenomena is a key feature to model granular flows such as landslides. Here, we investigated the instability that develops during the erosion of a wet granular pile by a dry dense granular flow. The morphology and the propagation of the generated steps are analyzed in relation to the specific erosion mechanism. The selected flowing angle of the confined flow on a dry heap appears to play an important role both in the final state of the experiment, and for the shape of the structures. We show that the development of the instability is governed by the inertia of the flow through the Froude number. We model this instability and predict growth rates that are in agreement with the experiment results. PMID:26919014

  16. Shear Instabilities in Granular Flows

    NASA Astrophysics Data System (ADS)

    Shinbrot, Troy

    2003-03-01

    Unstable waves have long been studied in fluid shear layers. These waves affect transport in the atmosphere and oceans as well as slipstream stability behind ships, planes, and heat transfer devices. Corresponding instabilities in granular flows have not previously been documented, despite the importance of these flows in geophysical and industrial systems. We report here that breaking waves can form at the interface between two streams of identical grains downstream of a splitter plate. These waves appear abruptly in flow down an inclined plane as either shear rate or angle of incline is changed, and we analyze a granular flow model that qualitatively agrees with our experimental data. The waves appear from the model to be a manifestation of a competition between shear and extensional strains in the flowing granular bed, and we propose a dimensionless group to govern the transition between steady and wavy flows.

  17. Shear instabilities in granular flows

    NASA Astrophysics Data System (ADS)

    Goldfarb, David J.; Glasser, Benjamin J.; Shinbrot, Troy

    2002-01-01

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows.

  18. Shear instabilities in granular flows.

    PubMed

    Goldfarb, David J; Glasser, Benjamin J; Shinbrot, Troy

    2002-01-17

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows. PMID:11797003

  19. Hierarchical Structures in Granular Matter

    NASA Astrophysics Data System (ADS)

    González-Gutiérrez, J.; Carrillo-Estrada, J. L.; Ruiz-Suárez, J. C.

    2013-12-01

    Granular matter, under the proper conditions of vibration, exhibits a behavior that closely resembles that of gases, liquids or solids. In a vibrated mix of glass particles and magnetic steel particles, it is also possible to observe aggregation phenomena, as well as, processes of reconstruction of the generated clusters. In this work we discuss the effects of the so called granular temperature on the evolution of the agglomerates generated by the magnetic interactions. On the basis of a fractal analysis and the measured mass distribution, we analyze experimental results on the static structural aspects of the aggregates originated by two methods we call: granular diffusion limited aggregation (GDLA) and growth limited by concentration (GLC).

  20. Electroweak and hadron studies

    SciTech Connect

    Rau, R.R.

    1988-01-01

    Some final results are presented on ..mu mu.., /tau//tau/, and hadron production, obtained by the MARK J collaboration at PETRA, over the cm energy band 22 GeV to 46.8 GeV. The MARK J results agree with world averaged data. They constitute powerful tests of the predictions of the Standard Model. 29 refs., 8 figs., 3 tabs.

  1. Hadron collider physics

    SciTech Connect

    Pondrom, L.

    1991-10-03

    An introduction to the techniques of analysis of hadron collider events is presented in the context of the quark-parton model. Production and decay of W and Z intermediate vector bosons are used as examples. The structure of the Electroweak theory is outlined. Three simple FORTRAN programs are introduced, to illustrate Monte Carlo calculation techniques. 25 refs.

  2. Initiation of immersed granular avalanches

    NASA Astrophysics Data System (ADS)

    Mutabaruka, Patrick; Delenne, Jean-Yves; Soga, Kenichi; Radjai, Farhang

    2014-05-01

    By means of coupled molecular dynamics-computational fluid dynamics simulations, we analyze the initiation of avalanches in a granular bed of spherical particles immersed in a viscous fluid and inclined above its angle of repose. In quantitative agreement with experiments, we find that the bed is unstable for a packing fraction below 0.59 but is stabilized above this packing fraction by negative excess pore pressure induced by the effect of dilatancy. From detailed numerical data, we explore the time evolution of shear strain, packing fraction, excess pore pressures, and granular microstructure in this creeplike pressure redistribution regime, and we show that they scale excellently with a characteristic time extracted from a model based on the balance of granular stresses in the presence of a negative excess pressure and its interplay with dilatancy. The cumulative shear strain at failure is found to be ≃0.2, in close agreement with the experiments, irrespective of the initial packing fraction and inclination angle. Remarkably, the avalanche is triggered when dilatancy vanishes instantly as a result of fluctuations while the average dilatancy is still positive (expanding bed) with a packing fraction that declines with the initial packing fraction. Another nontrivial feature of this creeplike regime is that, in contrast to dry granular materials, the internal friction angle of the bed at failure is independent of dilatancy but depends on the inclination angle, leading therefore to a nonlinear dependence of the excess pore pressure on the inclination angle. We show that this behavior may be described in terms of the contact network anisotropy, which increases with a nearly constant connectivity and levels off at a value (critical state) that increases with the inclination angle. These features suggest that the behavior of immersed granular materials is controlled not only directly by hydrodynamic forces acting on the particles but also by the influence of the

  3. Initiation of immersed granular avalanches.

    PubMed

    Mutabaruka, Patrick; Delenne, Jean-Yves; Soga, Kenichi; Radjai, Farhang

    2014-05-01

    By means of coupled molecular dynamics-computational fluid dynamics simulations, we analyze the initiation of avalanches in a granular bed of spherical particles immersed in a viscous fluid and inclined above its angle of repose. In quantitative agreement with experiments, we find that the bed is unstable for a packing fraction below 0.59 but is stabilized above this packing fraction by negative excess pore pressure induced by the effect of dilatancy. From detailed numerical data, we explore the time evolution of shear strain, packing fraction, excess pore pressures, and granular microstructure in this creeplike pressure redistribution regime, and we show that they scale excellently with a characteristic time extracted from a model based on the balance of granular stresses in the presence of a negative excess pressure and its interplay with dilatancy. The cumulative shear strain at failure is found to be ≃ 0.2, in close agreement with the experiments, irrespective of the initial packing fraction and inclination angle. Remarkably, the avalanche is triggered when dilatancy vanishes instantly as a result of fluctuations while the average dilatancy is still positive (expanding bed) with a packing fraction that declines with the initial packing fraction. Another nontrivial feature of this creeplike regime is that, in contrast to dry granular materials, the internal friction angle of the bed at failure is independent of dilatancy but depends on the inclination angle, leading therefore to a nonlinear dependence of the excess pore pressure on the inclination angle. We show that this behavior may be described in terms of the contact network anisotropy, which increases with a nearly constant connectivity and levels off at a value (critical state) that increases with the inclination angle. These features suggest that the behavior of immersed granular materials is controlled not only directly by hydrodynamic forces acting on the particles but also by the influence of the

  4. Density waves in granular flow

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Flekkøy, E.; Nagel, K.; Peng, G.; Ristow, G.

    Ample experimental evidence has shown the existence of spontaneous density waves in granular material flowing through pipes or hoppers. Using Molecular Dynamics Simulations we show that several types of waves exist and find that these density fluctuations follow a 1/f spectrum. We compare this behaviour to deterministic one-dimensional traffic models. If positions and velocities are continuous variables the model shows self-organized criticality driven by the slowest car. We also present Lattice Gas and Boltzmann Lattice Models which reproduce the experimentally observed effects. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow.

  5. DUNE - a granular flow code

    SciTech Connect

    Slone, D M; Cottom, T L; Bateson, W B

    2004-11-23

    DUNE was designed to accurately model the spectrum of granular. Granular flow encompasses the motions of discrete particles. The particles are macroscopic in that there is no Brownian motion. The flow can be thought of as a dispersed phase (the particles) interacting with a fluid phase (air or water). Validation of the physical models proceeds in tandem with simple experimental confirmation. The current development team is working toward the goal of building a flexible architecture where existing technologies can easily be integrated to further the capability of the simulation. We describe the DUNE architecture in some detail using physics models appropriate for an imploding liner experiment.

  6. Extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements

    NASA Technical Reports Server (NTRS)

    Franco, V.

    1977-01-01

    A method is presented for extracting hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements within the framework of the Glauber approximation. This method, which involves the solution of a linear integral equation, is applied to pn collisions between 15 and 275 GeV/c. Effects arising from inelastic intermediate states are estimated.

  7. Dynamic granularity of imaging systems

    DOE PAGESBeta

    Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; Porter, John L.

    2015-11-04

    Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the “dynamic granularity” Gdyn as a standardized, objective relation between a detector’s spatial resolution (granularity) and dynamic range for complex imaging systems in a given environment rathermore » than the widely found characterization of detectors such as cameras or films by themselves. We found that this relation can partly be explained through consideration of the signal’s photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging system’s performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. Our article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandia’s Z-Backlighter facility.« less

  8. Dynamic granularity of imaging systems

    SciTech Connect

    Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; Porter, John L.

    2015-11-04

    Imaging systems that include a specific source, imaging concept, geometry, and detector have unique properties such as signal-to-noise ratio, dynamic range, spatial resolution, distortions, and contrast. Some of these properties are inherently connected, particularly dynamic range and spatial resolution. It must be emphasized that spatial resolution is not a single number but must be seen in the context of dynamic range and consequently is better described by a function or distribution. We introduce the “dynamic granularity” Gdyn as a standardized, objective relation between a detector’s spatial resolution (granularity) and dynamic range for complex imaging systems in a given environment rather than the widely found characterization of detectors such as cameras or films by themselves. We found that this relation can partly be explained through consideration of the signal’s photon statistics, background noise, and detector sensitivity, but a comprehensive description including some unpredictable data such as dust, damages, or an unknown spectral distribution will ultimately have to be based on measurements. Measured dynamic granularities can be objectively used to assess the limits of an imaging system’s performance including all contributing noise sources and to qualify the influence of alternative components within an imaging system. Our article explains the construction criteria to formulate a dynamic granularity and compares measured dynamic granularities for different detectors used in the X-ray backlighting scheme employed at Sandia’s Z-Backlighter facility.

  9. Mechanics of granular materials (MGM)

    NASA Astrophysics Data System (ADS)

    Alshibli, Khalid A.; Costes, Nicholas C.; Porter, Ronald F.

    1996-07-01

    The constitutive behavior of uncemented granular materials such as strength, stiffness, and localization of deformations are to a large extent derived from interparticle friction transmitted between solid particles and particle groups. Interparticle forces are highly dependent on gravitational body forces. At very low effective confining pressures, the true nature of the Mohr envelope, which defines the Mohr-Coulomb failure criterion for soils, as well as the relative contribution of each of non-frictional components to soil's shear strength cannot be evaluated in terrestrial laboratories. Because of the impossibility of eliminating gravitational body forces on earth, the weight of soil grains develops interparticle compressive stresses which mask true soil constitutive behavior even in the smallest samples of models. Therefore the microgravity environment induced by near-earth orbits of spacecraft provides unique experimental opportunities for testing theories related to the mechanical behavior of terrestrial granular materials. Such materials may include cohesionless soils, industrial powders, crushed coal, etc. This paper will describe the microgravity experiment, 'Mechanics of Granular Materials (MGM)', scheduled to be flown on Space Shuttle-MIR missions. The paper will describe the experiment's hardware, instrumentation, specimen preparation procedures, testing procedures in flight, as well as a brief summary of the post-mission analysis. It is expected that the experimental results will significantly improve the understanding of the behavior of granular materials under very low effective stress levels.

  10. Mechanics of Granular Materials (MGM)

    NASA Technical Reports Server (NTRS)

    Alshibli, Khalid A.; Costes, Nicholas C.; Porter, Ronald F.

    1996-01-01

    The constitutive behavior of uncemented granular materials such as strength, stiffness, and localization of deformations are to a large extend derived from interparticle friction transmitted between solid particles and particle groups. Interparticle forces are highly dependent on gravitational body forces. At very low effective confining pressures, the true nature of the Mohr envelope, which defines the Mohr-Coulomb failure criterion for soils, as well as the relative contribution of each of non-frictional components to soil's shear strength cannot be evaluated in terrestrial laboratories. Because of the impossibility of eliminating gravitational body forces on earth, the weight of soil grains develops interparticle compressive stresses which mask true soil constitutive behavior even in the smallest samples of models. Therefore the microgravity environment induced by near-earth orbits of spacecraft provides unique experimental opportunities for testing theories related to the mechanical behavior of terrestrial granular materials. Such materials may include cohesionless soils, industrial powders, crushed coal, etc. This paper will describe the microgravity experiment, 'Mechanics of Granular Materials (MGM)', scheduled to be flown on Space Shuttle-MIR missions. The paper will describe the experiment's hardware, instrumentation, specimen preparation procedures, testing procedures in flight, as well as a brief summary of the post-mission analysis. It is expected that the experimental results will significantly improve the understanding of the behavior of granular materials under very low effective stress levels.

  11. Particle deposition in granular media: Progress report

    SciTech Connect

    Tien, Chi

    1987-01-01

    This paper discusses topics on particle deposition in granular media. The six topics discussed are: experimental determination of initial collection efficiency in granular beds - an assessment of the effect of instrument sensitivity and the extent of particle bounce-off; deposition of polydispersed aerosols in granular media; in situ observation of aerosol deposition in a two-dimensional model filter; solid velocity in cross-flow granular moving bed; aerosol deposition in granular moving bed; and aerosol deposition in a magnetically stabilized fluidized bed. (LSP)

  12. Charmed Hadron Interactions

    SciTech Connect

    Liu, Liuming

    2009-07-01

    We calculate the scattering lengths of the scattering processes where one or both hadrons contain charm quarks in full lattice QCD. We use relativistic Fermilab formulation for the charm quark. For the light quark, we use domain-wall fermions in the valence sector and improved Kogut- Susskind sea quarks. In J = Psi - N and D - K channels, we observe attractive interactions. In D - D* channel, the sign of the scattering length changes, which suggests a bound state.

  13. Spin in Hadron Reactions

    SciTech Connect

    Aidala, Christine A.

    2009-08-04

    The Relativistic Heavy Ion Collider (RHIC) has brought the study of spin effects in hadronic collisions to a new energy regime. In conjunction with other experiments at facilities around the world, much can be learned from the high-energy polarized proton collisions RHIC provides, allowing the collider to serve as a powerful tool to continue to understand the rich subtleties and surprises of spin effects in QCD, some of which were originally discovered more than three decades ago.

  14. QCD and Hadron Physics

    SciTech Connect

    Brodsky, Stanley J.; Deshpande, Abhay L.; Gao, Haiyan; McKeown, Robert D.; Meyer, Curtis A.; Meziani, Zein-Eddine; Milner, Richard G.; Qiu, Jianwei; Richards, David G.; Roberts, Craig D.

    2015-02-26

    This White Paper presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. The meeting was held in coordination with the Town Meeting on Phases of QCD and included a full day of joint plenary sessions of the two meetings. The goals of the meeting were to report and highlight progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and present a vision for the future by identifying the key questions and plausible paths to solutions which should define the next decade. The introductory summary details the recommendations and their supporting rationales, as determined at the Town Meeting on QCD and Hadron Physics, and the endorsements that were voted upon. The larger document is organized as follows. Section 2 highlights major progress since the 2007 LRP. It is followed, in Section 3, by a brief overview of the physics program planned for the immediate future. Finally, Section 4 provides an overview of the physics motivations and goals associated with the next QCD frontier: the Electron-Ion-Collider.

  15. Hadron Spin Dynamics

    SciTech Connect

    Brodsky, Stanley J.

    2002-01-09

    Spin effects in exclusive and inclusive reactions provide an essential new dimension for testing QCD and unraveling hadron structure. Remarkable new experiments from SLAC, HERMES (DESY), and Jefferson Lab present many challenges to theory, including measurements at HERMES and SMC of the single spin asymmetries in ep {yields} e{prime}{pi}X where the proton is polarized normal to the scattering plane. This type of single spin asymmetry may be due to the effects of rescattering of the outgoing quark on the spectators of the target proton, an effect usually neglected in conventional QCD analyses. Many aspects of spin, such as single-spin asymmetries and baryon magnetic moments are sensitive to the dynamics of hadrons at the amplitude level, rather than probability distributions. I will illustrate the novel features of spin dynamics for relativistic systems by examining the explicit form of the light-front wavefunctions for the two-particle Fock state of the electron in QED, thus connecting the Schwinger anomalous magnetic moment to the spin and orbital momentum carried by its Fock state constituents and providing a transparent basis for understanding the structure of relativistic composite systems and their matrix elements in hadronic physics. I also present a survey of outstanding spin puzzles in QCD, particularly A{sub NN} in elastic pp scattering, the J/{psi} {yields} {rho}{pi} puzzle, and J/{psi} polarization at the Tevatron.

  16. HYPERELASTIC MODELS FOR GRANULAR MATERIALS

    SciTech Connect

    Humrickhouse, Paul W; Corradini, Michael L

    2009-01-29

    A continuum framework for modeling of dust mobilization and transport, and the behavior of granular systems in general, has been reviewed, developed and evaluated for reactor design applications. The large quantities of micron-sized particles expected in the international fusion reactor design, ITER, will accumulate into piles and layers on surfaces, which are large relative to the individual particle size; thus, particle-particle, rather than particle-surface, interactions will determine the behavior of the material in bulk, and a continuum approach is necessary and justified in treating the phenomena of interest; e.g., particle resuspension and transport. The various constitutive relations that characterize these solid particle interactions in dense granular flows have been discussed previously, but prior to mobilization their behavior is not even fluid. Even in the absence of adhesive forces between particles, dust or sand piles can exist in static equilibrium under gravity and other forces, e.g., fluid shear. Their behavior is understood to be elastic, though not linear. The recent “granular elasticity” theory proposes a non-linear elastic model based on “Hertz contacts” between particles; the theory identifies the Coulomb yield condition as a requirement for thermodynamic stability, and has successfully reproduced experimental results for stress distributions in sand piles. The granular elasticity theory is developed and implemented in a stand- alone model and then implemented as part of a finite element model, ABAQUS, to determine the stress distributions in dust piles subjected to shear by a fluid flow. We identify yield with the onset of mobilization, and establish, for a given dust pile and flow geometry, the threshold pressure (force) conditions on the surface due to flow required to initiate it. While the granular elasticity theory applies strictly to cohesionless granular materials, attractive forces are clearly important in the interaction of

  17. Hadronization processes in neutrino interactions

    NASA Astrophysics Data System (ADS)

    Katori, Teppei; Mandalia, Shivesh

    2015-10-01

    Next generation neutrino oscillation experiments utilize details of hadronic final states to improve the precision of neutrino interaction measurements. The hadronic system was often neglected or poorly modelled in the past, but they have significant effects on high precision neutrino oscillation and cross-section measurements. Among the physics of hadronic systems in neutrino interactions, the hadronization model controls multiplicities and kinematics of final state hadrons from the primary interaction vertex. For relatively high invariant mass events, many neutrino experiments rely on the PYTHIA program. Here, we show a possible improvement of this process in neutrino event generators, by utilizing expertise from the HERMES experiment. Finally, we estimate the impact on the systematics of hadronization models for neutrino mass hierarchy analysis using atmospheric neutrinos such as the PINGU experiment.

  18. Hadronization processes in neutrino interactions

    SciTech Connect

    Katori, Teppei; Mandalia, Shivesh

    2015-10-15

    Next generation neutrino oscillation experiments utilize details of hadronic final states to improve the precision of neutrino interaction measurements. The hadronic system was often neglected or poorly modelled in the past, but they have significant effects on high precision neutrino oscillation and cross-section measurements. Among the physics of hadronic systems in neutrino interactions, the hadronization model controls multiplicities and kinematics of final state hadrons from the primary interaction vertex. For relatively high invariant mass events, many neutrino experiments rely on the PYTHIA program. Here, we show a possible improvement of this process in neutrino event generators, by utilizing expertise from the HERMES experiment. Finally, we estimate the impact on the systematics of hadronization models for neutrino mass hierarchy analysis using atmospheric neutrinos such as the PINGU experiment.

  19. High energy hadron-hadron collisions. [Dept. of Physics and Astronomy, Univ. of Georgia, Athens, Georgia

    SciTech Connect

    Chou, T.T.

    1992-01-01

    Results of a study on high energy collisions with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) e[sup +]e[sup [minus

  20. Stop and restart of granular clock in a vibrated compartmentalized bidisperse granular system

    NASA Astrophysics Data System (ADS)

    Liu, Qi-Yi; Hu, Mao-Bin; Jiang, Rui; Wu, Yong-Hong

    2013-01-01

    This paper studies a bidisperse granular mixture consisting of two species of stainless steel spheres in a vertically vibrated compartmentalized container. The experiments show that with proper vibration acceleration, the granular clock stops when horizontal segregation of the large spheres residing in the far end from the barrier wall occurs. When the segregation is broken, the granular clock restarts. We present the phase diagrams of vibration acceleration versus container width and small particle number, which exhibits three different regions, namely, clustering state, stop-restart of the granular clock, and the granular clock. A generalized flux model is proposed to reproduce the phenomenon of stop and restart of the granular clock.

  1. Mott transition in granular aluminum

    NASA Astrophysics Data System (ADS)

    Bachar, N.; Lerer, S.; Levy, A.; Hacohen-Gourgy, S.; Almog, B.; Saadaoui, H.; Salman, Z.; Morenzoni, E.; Deutscher, G.

    2015-01-01

    A Mott transition in granular Al films is observed by probing the increase of the spin-flip scattering rate of conduction electrons as the nanosize metallic grains are being progressively decoupled. The presence of free spins in granular Al films is directly demonstrated by μ SR measurements. Analysis of the magnetoresistance in terms of an effective Fermi energy shows that it becomes of the order of the grains electrostatic charging energy at a room temperature resistivity ρ300 K≈50000 μ Ω cm , at which a metal to insulator transition is known to exist. As this transition is approached the magnetoresistance exhibits a heavy-fermion-like behavior, consistent with an increased electron effective mass.

  2. Electrification of Shaken Granular Media

    NASA Astrophysics Data System (ADS)

    Kara, Onur; Nordsiek, Freja; Lathrop, Daniel

    2015-11-01

    Granular charging of particle laden flows are widespread and has long been observed. Volcanic ash clouds, desert sandstorms, dust devils, thunderstorms and snowstorms all undergo electrification at large scale. However the mechanism by which such processes occur, is not yet well understood. We confine granular particles to an oscillating cylindrical chamber which is enclosed and sealed by two conducting plates. The primary measurement obtained is the voltage between the two plates. We find that collective effects occurring in the bulk of the material play a significant role in the electrification process. We extend the previous results by the addition of photodectection capabilities to the experimental chamber. We present simultaneous measurements of voltage and light emission.

  3. Dilatancy in Slow Granular Flows

    NASA Astrophysics Data System (ADS)

    Kabla, Alexandre J.; Senden, Tim J.

    2009-06-01

    When walking on wet sand, each footstep leaves behind a temporarily dry impression. This counterintuitive observation is the most common illustration of the Reynolds principle of dilatancy: that is, a granular packing tends to expand as it is deformed, therefore increasing the amount of porous space. Although widely called upon in areas such as soil mechanics and geotechnics, a deeper understanding of this principle is constrained by the lack of analytical tools to study this behavior. Using x-ray radiography, we track a broad variety of granular flow profiles and quantify their intrinsic dilatancy behavior. These measurements frame Reynolds dilatancy as a kinematic process. Closer inspection demonstrates, however, the practical importance of flow induced compaction which competes with dilatancy, leading more complex flow properties than expected.

  4. Dilatancy in slow granular flows.

    PubMed

    Kabla, Alexandre J; Senden, Tim J

    2009-06-01

    When walking on wet sand, each footstep leaves behind a temporarily dry impression. This counterintuitive observation is the most common illustration of the Reynolds principle of dilatancy: that is, a granular packing tends to expand as it is deformed, therefore increasing the amount of porous space. Although widely called upon in areas such as soil mechanics and geotechnics, a deeper understanding of this principle is constrained by the lack of analytical tools to study this behavior. Using x-ray radiography, we track a broad variety of granular flow profiles and quantify their intrinsic dilatancy behavior. These measurements frame Reynolds dilatancy as a kinematic process. Closer inspection demonstrates, however, the practical importance of flow induced compaction which competes with dilatancy, leading more complex flow properties than expected. PMID:19658906

  5. Compaction Behavior of Granular Materials

    NASA Astrophysics Data System (ADS)

    Endicott, Mark R.; Kenkre, V. M.; Glass, S. Jill; Hurd, Alan J.

    1996-03-01

    We report the results of our recent study of compaction of granular materials. A theoretical model is developed for the description of the compaction of granular materials exemplified by granulated ceramic powders. Its predictions are compared to observations of uniaxial compaction tests of ceramic granules of PMN-PT, spray dried alumina and rutile. The theoretical model employs a volume-based statistical mechanics treatment and an activation analogy. Results of a computer simulation of random packing of discs in two dimensions are also reported. The effect of type of particle size distribution and other parameters of that distribution on the calculated quantities are discussed. We examine the implications of the results of the simulation for the theoretical model.

  6. Shear deformation in granular materials

    SciTech Connect

    Bardenhagen, S.G.; Brackbill, J.U.; Sulsky, D.L.

    1998-12-31

    An investigation into the properties of granular materials is undertaken via numerical simulation. These simulations highlight that frictional contact, a defining characteristic of dry granular materials, and interfacial debonding, an expected deformation mode in plastic bonded explosives, must be properly modeled. Frictional contact and debonding algorithms have been implemented into FLIP, a particle in cell code, and are described. Frictionless and frictional contact are simulated, with attention paid to energy and momentum conservation. Debonding is simulated, with attention paid to the interfacial debonding speed. A first step toward calculations of shear deformation in plastic bonded explosives is made. Simulations are performed on the scale of the grains where experimental data is difficult to obtain. Two characteristics of deformation are found, namely the intermittent binding of grains when rotation and translation are insufficient to accommodate deformation, and the role of the binder as a lubricant in force chains.

  7. Dynamic compaction of granular materials

    PubMed Central

    Favrie, N.; Gavrilyuk, S.

    2013-01-01

    An Eulerian hyperbolic multiphase flow model for dynamic and irreversible compaction of granular materials is constructed. The reversible model is first constructed on the basis of the classical Hertz theory. The irreversible model is then derived in accordance with the following two basic principles. First, the entropy inequality is satisfied by the model. Second, the corresponding ‘intergranular stress’ coming from elastic energy owing to contact between grains decreases in time (the granular media behave as Maxwell-type materials). The irreversible model admits an equilibrium state corresponding to von Mises-type yield limit. The yield limit depends on the volume fraction of the solid. The sound velocity at the yield surface is smaller than that in the reversible model. The last one is smaller than the sound velocity in the irreversible model. Such an embedded model structure assures a thermodynamically correct formulation of the model of granular materials. The model is validated on quasi-static experiments on loading–unloading cycles. The experimentally observed hysteresis phenomena were numerically confirmed with a good accuracy by the proposed model. PMID:24353466

  8. Bipedal locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Kingsbury, Mark; Zhang, Tingnan; Goldman, Daniel

    Bipedal walking, locomotion characterized by alternating swing and double support phase, is well studied on ground where feet do not penetrate the substrate. On granular media like sand however, intrusion and extrusion phases also occur. In these phases, relative motion of the two feet requires that one or both feet slip through the material, degrading performance. To study walking in these phases, we designed and studied a planarized bipedal robot (1.6 kg, 42 cm) that walked in a fluidized bed of poppy seeds. We also simulated the robot in a multibody software environment (Chrono) using granular resistive force theory (RFT) to calculate foot forces. In experiment and simulation, the robot experienced slip during the intrusion phase, with the experiment presenting additional slip due to motor control error during the double support phase. This exaggerated slip gave insight (through analysis of ground reaction forces in simulation) into how slip occurs when relative motion exists between the two feet in the granular media, where the foot with higher relative drag forces (from its instantaneous orientation, rotation, relative direction of motion, and depth) remains stationary. With this relationship, we generated walking gaits for the robot to walk with minimal slip.

  9. High energy hadron-hadron collisions. Annual progress report

    SciTech Connect

    Chou, T.T.

    1992-12-31

    Results of a study on high energy collisions with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) e{sup +}e{sup {minus}} annihilation. For elastic scattering, a modified form for the hadronic matter form factor of the proton was proposed which is still dipole in form but contains an energy--dependent range parameter. This new expression of the opacity function fits the elastic {bar p}p scattering very well from the ISR to S{bar p}pS energies. Extrapolation of this theory also yielded results {bar p}p in good agreement with the {bar p}p differential cross section measured at the Tevatron. For inelastic hadron-hadron collisions, we have made a systematic investigation of the single-particle momentum spectra in the entire S{bar p}pS energy region. Results are useful for the extrapolation of angular distribution to the higher SSC energies. In e{sup +}e{sup {minus}} annihilation, a detailed analysis of all available experimental multiplicity data from PETRA to LEP energies has been performed. The cluster size of emitted hadrons increases gradually with energy. Aside from high-energy collisions, the giant fullerene molecules were studied and precise algebraic eigenvalue expressions of the Hueckel problem for carbon-240 were obtained.

  10. High energy hadron-hadron collisions. Annual progress report

    SciTech Connect

    Chou, T.T.

    1991-12-01

    Results of a study on high energy collision with the geometrical model are summarized in three parts: (1) the elastic hadron-hadron collision, (2) the inelastic hadron-hadron collision, and (3) the e{sup +}e{sup {minus}} annihilation. More recent studies are highlighted below. For elastic scattering, a modified form for the hadronic matter form factor of the proton was proposed which remains to be dipole in form but contains an energy-dependent range parameter. This new expression of the opacity function fits the elastic {bar p}p scattering very well from the ISR to S{bar p}pS energies. Extrapolation of this theory also yielded results in good agreement with the {bar p}p differential cross section measured at the Tevatron. For inelastic hadron-hadron collisions, we have made a systematic investigation of the single-particle momentum spectra in the entire S{bar p}pS energy region. Results are useful for the extrapolation of angular distribution to the higher SSC energies. In e{sup +}e{sup {minus}} annihilation, a detailed analysis of all available experimental multiplicity data from PETRA to LEP energies has been performed. We discovered that the cluster size of emitted hadrons increases steadily with energy and is close to 2 as we predicted.

  11. Monte Carlo event generators for hadron-hadron collisions

    SciTech Connect

    Knowles, I.G.; Protopopescu, S.D.

    1993-06-01

    A brief review of Monte Carlo event generators for simulating hadron-hadron collisions is presented. Particular emphasis is placed on comparisons of the approaches used to describe physics elements and identifying their relative merits and weaknesses. This review summarizes a more detailed report.

  12. Quarkonia production with leptons and hadrons

    SciTech Connect

    V. Papadimitriou

    2004-06-09

    We discuss current issues and present the latest measurements on quarkonia production from experiments monitoring hadron-hadron and lepton-hadron collisions. These measurements include cross section and polarization results for charmonium and bottomonium states.

  13. Gamma-hadron families and scaling violation

    NASA Technical Reports Server (NTRS)

    Gaisser, T. K.; Stanev, T.; Wrotniak, J. A.

    1985-01-01

    For three different interaction models we have simulated gamma-hadron families, including the detector (Pamir emulsion chamber) response. Rates of gamma families, hadrons, and hadron-gamma ratios were compared with experiments.

  14. Confinement and hadron-hadron interactions by general relativistic methods

    NASA Astrophysics Data System (ADS)

    Recami, Erasmo

    By postulating covariance of physical laws under global dilations, one can describe gravitational and strong interactions in a unified way. Namely, in terms of the new discrete dilational degree of freedom, our cosmos and hadrons can be regarded as finite, similar systems. And a discrete hierarchy of finite ``universes'' may be defined, which are governed by fields with strengths inversally proportional to their radii; in each universe an Equivalence Principle holds, so that the relevant field can be there geometrized. Scaled-down Einstein equations -with cosmological term- are assumed to hold inside hadrons (= strong micro-cosmoses); and they yield in a natural way classical confinement, as well as ``asymptotic freedom'', of the hadron constituents. In other words, the association of strong micro-universes of Friedmann type with hadrons (i.e., applying the methods of General Relativity to subnuclear particle physics) allows avoiding recourse to phenomenological models such as the Bag Model. Inside hadrons we have to deal with a tensorial field (= strong gravity), and hadron constituents are supposed to exchange spin-2 ``gluons''. Our approach allows us also to write down a tensorial, bi-scale field theory of hadron-hadron interactions, based on modified Einstein-type equations here proposed for strong interactions in our space. We obtain in particular: (i) the correct Yukawa behaviour of the strong scalar potential at the static limit and for r>~l fm; (ii) the value of hadron radii. As a byproduct, we derive a whole ``numerology'', connecting our gravitational cosmos with the strong micro-cosmoses (hadrons), such that it does imply no variation of G with the epoch. Finally, since a structute of the ``micro-universe'' type seems to be characteristic even of leptons, a hope for the future is including also weak interactions in our classical unification of the fundamental forces.

  15. Anisotropy of weakly vibrated granular flows.

    PubMed

    Wortel, Geert H; van Hecke, Martin

    2015-10-01

    We experimentally probe the anisotropy of weakly vibrated flowing granular media. Depending on the driving parameters-flow rate and vibration strength-this anisotropy varies significantly. We show how the anisotropy collapses when plotted as a function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggest that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a crucial role in determining the rheology of granular flows. PMID:26565148

  16. Anisotropy of weakly vibrated granular flows

    NASA Astrophysics Data System (ADS)

    Wortel, Geert H.; van Hecke, Martin

    2015-10-01

    We experimentally probe the anisotropy of weakly vibrated flowing granular media. Depending on the driving parameters—flow rate and vibration strength—this anisotropy varies significantly. We show how the anisotropy collapses when plotted as a function of the driving stresses, uncovering a direct link between stresses and anisotropy. Moreover, our data suggest that for small anisotropies, the shear stresses vanish. Anisotropy of the fabric of granular media thus plays a crucial role in determining the rheology of granular flows.

  17. Modelling Hadronic Matter

    NASA Astrophysics Data System (ADS)

    Menezes, Débora P.

    2016-04-01

    Hadron physics stands somewhere in the diffuse intersection between nuclear and particle physics and relies largely on the use of models. Historically, around 1930, the first nuclear physics models known as the liquid drop model and the semi-empirical mass formula established the grounds for the study of nuclei properties and nuclear structure. These two models are parameter dependent. Nowadays, around 500 hundred non-relativistic (Skyrme-type) and relativistic models are available in the literature and largely used and the vast majority are parameter dependent models. In this review I discuss some of the shortcomings of using non-relativistic models and the advantages of using relativistic ones when applying them to describe hadronic matter. I also show possible applications of relativistic models to physical situations that cover part of the QCD phase diagram: I mention how the description of compact objects can be done, how heavy-ion collisions can be investigated and particle fractions obtained and show the relation between liquid-gas phase transitions and the pasta phase.

  18. Results from hadron colliders

    SciTech Connect

    Pondrom, L.G. )

    1990-12-14

    The present status of hadron collider physics is reviewed. The total cross section for {bar p} + p has been measured at 1.8 TeV: {sigma}{sub tot} = 72.1 {plus minus} 3.3 mb. New data confirm the UA2 observation of W/Z {yields} {bar q}q. Precision measurements of M{sub W} by UA2 and CDF give an average value M{sub W} = 80.13 {plus minus} 0.30 GeV/c{sup 2}. When combined with measurements of M{sub Z} from LEP and SLC this number gives sin{sup 2}{theta}{sub W} = 0.227 {plus minus} 0.006, or m{sub top} = 130{sub {minus}60}{sup +40} GeV/c{sup 2} from the EWK radiative correction term {Delta}r. Evidence for hadron colliders as practical sources of b quarks has been strengthened, while searches for t quarks have pushed the mass above M{sub W}: m{sub top} > 89 GeV/c{sup 2} 95% cl (CDF Preliminary). Searches beyond the standard model based on the missing E{sub T} signature have not yet produced any positive results. Future prospects for the discovery of the top quark in the range m{sub top} < 200 GeV/c{sup 2} look promising. 80 refs., 35 figs., 7 tabs.

  19. A new hadron spectroscopy

    NASA Astrophysics Data System (ADS)

    Olsen, Stephen Lars

    2015-04-01

    QCD-motivated models for hadrons predict an assortment of "exotic" hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons, the six-quark H-dibaryon, and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed-anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD-inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states -the proton-antiproton state and the so-called XY Z mesons- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.

  20. On the Hadronic Mass Spectrum

    NASA Astrophysics Data System (ADS)

    Hagedorn, Rolf

    We argue that the sole requirement of a self-consistent bootstrap including all hadrons up to infinite mass leads to asymptotically exponential laws for the hadron mass spectrum, for momentum distributions, and for form factors (and to a highest temperature).

  1. Quarkonium production in hadronic collisions

    SciTech Connect

    Gavai, R.; Schuler, G.A.; Sridhar, K.

    1995-07-01

    We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.

  2. Current Status of Exotic Hadrons

    SciTech Connect

    Saeed, M.A.; Ahmed, Maqsood; Fazal-e-Aleem

    2005-03-17

    Physics of exotic hadrons is in the limelight these days. The models for these baryons are discussed as well as their production and decay processes and methods of their identification. The results of recent experiments in this field are presented, in which some unusual states are observed. These states are candidates for exotic hadrons.

  3. Dynamics of Sheared Granular Materials

    NASA Astrophysics Data System (ADS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-11-01

    This work focuses on the properties of sheared granular materials near the jamming transition. The project currently involves two aspects. The first of these is an experiment that is a prototype for a planned ISS (International Space Station) flight. The second is discrete element simulations (DES) that can give insight into the behavior one might expect in a reduced-g environment. The experimental arrangement consists of an annular channel that contains the granular material. One surface, say the upper surface, rotates so as to shear the material contained in the annulus. The lower surface controls the mean density/mean stress on the sample through an actuator or other control system. A novel feature under development is the ability to 'thermalize' the layer, i.e. create a larger amount of random motion in the material, by using the actuating system to provide vibrations as well control the mean volume of the annulus. The stress states of the system are determined by transducers on the non-rotating wall. These measure both shear and normal components of the stress on different size scales. Here, the idea is to characterize the system as the density varies through values spanning dense almost solid to relatively mobile granular states. This transition regime encompasses the regime usually thought of as the glass transition, and/or the jamming transition. Motivation for this experiment springs from ideas of a granular glass transition, a related jamming transition, and from recent experiments. In particular, we note recent experiments carried out by our group to characterize this type of transition and also to demonstrate/ characterize fluctuations in slowly sheared systems. These experiments give key insights into what one might expect in near-zero g. In particular, they show that the compressibility of granular systems diverges at a transition or critical point. It is this divergence, coupled to gravity, that makes it extremely difficult if not impossible to

  4. Dynamics of Sheared Granular Materials

    NASA Technical Reports Server (NTRS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-01-01

    This work focuses on the properties of sheared granular materials near the jamming transition. The project currently involves two aspects. The first of these is an experiment that is a prototype for a planned ISS (International Space Station) flight. The second is discrete element simulations (DES) that can give insight into the behavior one might expect in a reduced-g environment. The experimental arrangement consists of an annular channel that contains the granular material. One surface, say the upper surface, rotates so as to shear the material contained in the annulus. The lower surface controls the mean density/mean stress on the sample through an actuator or other control system. A novel feature under development is the ability to 'thermalize' the layer, i.e. create a larger amount of random motion in the material, by using the actuating system to provide vibrations as well control the mean volume of the annulus. The stress states of the system are determined by transducers on the non-rotating wall. These measure both shear and normal components of the stress on different size scales. Here, the idea is to characterize the system as the density varies through values spanning dense almost solid to relatively mobile granular states. This transition regime encompasses the regime usually thought of as the glass transition, and/or the jamming transition. Motivation for this experiment springs from ideas of a granular glass transition, a related jamming transition, and from recent experiments. In particular, we note recent experiments carried out by our group to characterize this type of transition and also to demonstrate/ characterize fluctuations in slowly sheared systems. These experiments give key insights into what one might expect in near-zero g. In particular, they show that the compressibility of granular systems diverges at a transition or critical point. It is this divergence, coupled to gravity, that makes it extremely difficult if not impossible to

  5. Hadron accelerators for radiotherapy

    NASA Astrophysics Data System (ADS)

    Owen, Hywel; MacKay, Ranald; Peach, Ken; Smith, Susan

    2014-04-01

    Over the last twenty years the treatment of cancer with protons and light nuclei such as carbon ions has moved from being the preserve of research laboratories into widespread clinical use. A number of choices now exist for the creation and delivery of these particles, key amongst these being the adoption of pencil beam scanning using a rotating gantry; attention is now being given to what technologies will enable cheaper and more effective treatment in the future. In this article the physics and engineering used in these hadron therapy facilities is presented, and the research areas likely to lead to substantive improvements. The wider use of superconducting magnets is an emerging trend, whilst further ahead novel high-gradient acceleration techniques may enable much smaller treatment systems. Imaging techniques to improve the accuracy of treatment plans must also be developed hand-in-hand with future sources of particles, a notable example of which is proton computed tomography.

  6. Hadron production experiments

    NASA Astrophysics Data System (ADS)

    Popov, Boris A.

    2013-02-01

    The HARP and NA61/SHINE hadroproduction experiments as well as their implications for neutrino physics are discussed. HARP measurements have already been used for predictions of neutrino beams in K2K and MiniBooNE/SciBooNE experiments and are also being used to improve the atmospheric neutrino flux predictions and to help in the optimization of neutrino factory and super-beam designs. First measurements released recently by the NA61/SHINE experiment are of significant importance for a precise prediction of the J-PARC neutrino beam used for the T2K experiment. Both HARP and NA61/SHINE experiments provide also a large amount of input for validation and tuning of hadron production models in Monte-Carlo generators.

  7. Inter/intra granular exchange and thermal activation in nanoscale granular magnetic materials

    NASA Astrophysics Data System (ADS)

    Morrison, C.; Saharan, L.; Hrkac, G.; Schrefl, T.; Ikeda, Y.; Takano, K.; Miles, J. J.; Thomson, T.

    2011-09-01

    We explain the effect of inter/intra granular exchange coupling and thermal activation on the switching behavior of nano-scale granular magnetic materials. For an ideal, non-interacting granular system, the minimum switching field occurs at 45° from the easy axis of the grains. We show through simulation and measurements, using a CoCrPt oxide-segregated granular film as a model system, that there is a clear shift in the angle of applied field at which the minimum switching field occurs. This arises solely due to incoherent reversal induced by inter-granular exchange coupling or incoherency within larger grains, rather than thermal activation.

  8. Aging in humid granular media.

    PubMed

    Restagno, Frédéric; Ursini, Cécile; Gayvallet, Hervé; Charlaix, Elisabeth

    2002-08-01

    Aging behavior is an important effect in the friction properties of solid surfaces. In this paper we investigate the temporal evolution of the static properties of a granular medium by studying the aging over time of the maximum stability angle of submillimetric glass beads. We report the effect of several parameters on these aging properties, such as the wear on the beads, the stress during the resting period, and the humidity content of the atmosphere. Aging effects in an ethanol atmosphere are also studied. These experimental results are discussed at the end of the paper. PMID:12241167

  9. Theoretical model of granular compaction

    SciTech Connect

    Ben-Naim, E.; Knight, J.B.; Nowak, E.R. |; Jaeger, H.M.; Nagel, S.R.

    1997-11-01

    Experimental studies show that the density of a vibrated granular material evolves from a low density initial state into a higher density final steady state. The relaxation towards the final density follows an inverse logarithmic law. As the system approaches its final state, a growing number of beads have to be rearranged to enable a local density increase. A free volume argument shows that this number grows as N = {rho}/(1 {minus} {rho}). The time scale associated with such events increases exponentially e{sup {minus}N}, and as a result a logarithmically slow approach to the final state is found {rho} {infinity} {minus}{rho}(t) {approx_equal} 1/lnt.

  10. Hydrodynamic modes for granular gases.

    PubMed

    Dufty, James W; Brey, J Javier

    2003-09-01

    The eigenfunctions and eigenvalues of the linearized Boltzmann equation for inelastic hard spheres (d=3) or disks (d=2) corresponding to d+2 hydrodynamic modes are calculated in the long wavelength limit for a granular gas. The transport coefficients are identified and found to agree with those from the Chapman-Enskog solution. The dominance of hydrodynamic modes at long times and long wavelengths is studied via an exactly solvable kinetic model. A collisional continuum is bounded away from the hydrodynamic spectrum, assuring a hydrodynamic description at long times. The bound is closely related to the power law decay of the velocity distribution in the reference homogeneous cooling state. PMID:14524742

  11. Thermoelectric performance of granular semiconductors.

    SciTech Connect

    Glatz, A.; Beloborodov, I. S.; Materials Science Division; California State Univ.

    2009-01-01

    We study the effects of doping and confinement on the thermoelectric properties of nanocrystalline semiconductors. We calculate the thermopower and figure of merit for temperatures less than the charging energy. For weakly coupled semiconducting grains it is shown that the figure of merit is optimized for grain sizes of order 5 nm for typical materials, and that its value can be larger than one. Using the similarities between granular semiconductors and electron or Coulomb glasses allows for a quantitative description of inhomogeneous semiconducting thermoelectrics.

  12. Where the Granular Flows Bend

    NASA Astrophysics Data System (ADS)

    Khomenko, E.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.; Gandorfer, A.; Bonet, J. A.; Domingo, V.; Schmidt, W.; Barthol, P.; Knölker, M.

    2010-11-01

    Based on IMaX/SUNRISE data, we report on a previously undetected phenomenon in solar granulation. We show that in a very narrow region separating granules and intergranular lanes, the spectral line width of the Fe I 5250.2 Å line becomes extremely small. We offer an explanation of this observation with the help of magneto-convection simulations. These regions with extremely small line widths correspond to the places where the granular flows bend from upflow in granules to downflow in intergranular lanes. We show that the resolution and image stability achieved by IMaX/SUNRISE are important requisites to detect this interesting phenomenon.

  13. Heavy quarks in hadronic collisions

    SciTech Connect

    Brodsky, S.J.; Peterson, C.

    1982-03-01

    It is suggested that the presence of c anti c-pairs on the 1 to 2% level in the hadron Fock state decomposition (intrinsic charm) gives a natural description of the ISR data for charm hadron production. The theoretical foundations of the intrinsic charm hypothesis together with its consequences for lepton- and hadron-induced reactions are discussed in some detail. There is no contradiction with the EMC data on F/sub 2//sup c/ provided the appropriate threshold dependence is taken into account.

  14. Hadron collider physics at UCR

    SciTech Connect

    Kernan, A.; Shen, B.C.

    1997-07-01

    This paper describes the research work in high energy physics by the group at the University of California, Riverside. Work has been divided between hadron collider physics and e{sup +}-e{sup {minus}} collider physics, and theoretical work. The hadron effort has been heavily involved in the startup activities of the D-Zero detector, commissioning and ongoing redesign. The lepton collider work has included work on TPC/2{gamma} at PEP and the OPAL detector at LEP, as well as efforts on hadron machines.

  15. Centrifuge modelling of granular flows

    NASA Astrophysics Data System (ADS)

    Cabrera, Miguel Angel; Wu, Wei

    2015-04-01

    A common characteristic of mass flows like debris flows, rock avalanches and mudflows is that gravity is their main driving force. Gravity defines the intensity and duration of the main interactions between particles and their surrounding media (particle-particle, particle-fluid, fluid-fluid). At the same time, gravity delimits the occurrence of phase separation, inverse segregation, and mass consolidation, among other phenomena. Therefore, in the understanding of the flow physics it is important to account for the scaling of gravity in scaled models. In this research, a centrifuge model is developed to model free surface granular flows down an incline at controlled gravity conditions. Gravity is controlled by the action of an induced inertial acceleration field resulting from the rotation of the model in a geotechnical centrifuge. The characteristics of the induced inertial acceleration field during flow are discussed and validated via experimental data. Flow heights, velocity fields, basal pressure and impact forces are measured for a range of channel inclinations and gravity conditions. Preliminary results enlighten the flow characteristics at variable gravity conditions and open a discussion on the simulation of large scale processes at a laboratory scale. Further analysis on the flow physics brings valuable information for the validation of granular flows rheology.

  16. Compaction Waves in Granular HMX

    SciTech Connect

    E. Kober; R. Menikoff

    1999-01-01

    Piston driven compaction waves in granular HMX are simulated with a two-dimensional continuum mechanics code in which individual grains are resolved. The constitutive properties of the grains are modeled with a hydrostatic pressure and a simple elastic-plastic model for the shear stress. Parameters are chosen to correspond to inert HMX. For a tightly packed random grain distribution (with initial porosity of 19%) we varied the piston velocity to obtain weak partly compacted waves and stronger fully compacted waves. The average stress and wave speed are compatible with the porous Hugoniot locus for uni- axial strain. However, the heterogeneities give rise to stress concentrations, which lead to localized plastic flow. For weak waves, plastic deformation is the dominant dissipative mechanism and leads to dispersed waves that spread out in time. In addition to dispersion, the granular heterogeneities give rise to subgrain spatial variation in the thermodynamic variables. The peaks in the temperature fluctuations, known as hot spots, are in the range such that they are the critical factor for initiation sensitivity.

  17. Modeling Size Polydisperse Granular Flows

    NASA Astrophysics Data System (ADS)

    Lueptow, Richard M.; Schlick, Conor P.; Isner, Austin B.; Umbanhowar, Paul B.; Ottino, Julio M.

    2014-11-01

    Modeling size segregation of granular materials has important applications in many industrial processes and geophysical phenomena. We have developed a continuum model for granular multi- and polydisperse size segregation based on flow kinematics, which we obtain from discrete element method (DEM) simulations. The segregation depends on dimensionless control parameters that are functions of flow rate, particle sizes, collisional diffusion coefficient, shear rate, and flowing layer depth. To test the theoretical approach, we model segregation in tri-disperse quasi-2D heap flow and log-normally distributed polydisperse quasi-2D chute flow. In both cases, the segregated particle size distributions match results from full-scale DEM simulations and experiments. While the theory was applied to size segregation in steady quasi-2D flows here, the approach can be readily generalized to include additional drivers of segregation such as density and shape as well as other geometries where the flow field can be characterized including rotating tumbler flow and three-dimensional bounded heap flow. Funded by The Dow Chemical Company and NSF Grant CMMI-1000469.

  18. Extensional Rheology of Granular Staples

    NASA Astrophysics Data System (ADS)

    Franklin, Scott

    2013-03-01

    Collections of U-shaped granular materials (e.g. staples) show a surprising resistance to being pulled apart. We conduct extensional stress-strain experiments on staple piles with vary arm/spine (barb) ratio. The elongation is not smooth, with the pile growing in bursts, reminiscent of intruder motion through ordinary and rod-like granular materials. The force-distance curve shows a power-law scaling, consistent with previous intruder experiments. Surprisingly, there is significant plastic creep of the pile as particles rearrange slightly in response to the increasing force. There is a broad distribution of yield forces that does not seem to evolve as the pile lengthens, suggesting that each yield event is independent of the pile's history. The distribution of yield forces can be interpreted in the context of a Weibullian weakest-link theory that predicts the maximum pile strength to decrease sharply with increasing pile length. From this interpretation arise length and force scales that may be used to characterize the sample. This research supported in part by the NSF (CBET-#1133722) and ACS-PRF (#51438-UR10).

  19. Hadron-Quark Phase Transition

    SciTech Connect

    Cavagnoli, Rafael; Menezes, Debora P.; Providencia, Constanca

    2009-06-03

    In the present work we study the hadron-quarkphase transition with boson condensation by investigating the binodal surface and extending it to finite temperature in order to mimic the QCD phase diagram.

  20. The CMS central hadron calorimeter

    SciTech Connect

    Freeman, J.

    1998-11-01

    The CMS central hadron calorimeter is a brass absorber/scintillator sampling structure. We describe details of the mechanical and optical structure. We also discuss calibration techniques, and finally the anticipated construction schedule. {copyright} {ital 1998 American Institute of Physics.}

  1. Numerical Simulations of Granular Processes

    NASA Astrophysics Data System (ADS)

    Richardson, Derek C.; Michel, Patrick; Schwartz, Stephen R.; Ballouz, Ronald-Louis; Yu, Yang; Matsumura, Soko

    2014-11-01

    Spacecraft images and indirect observations including thermal inertia measurements indicate most small bodies have surface regolith. Evidence of granular flow is also apparent in the images. This material motion occurs in very low gravity, therefore in a completely different gravitational environment than on the Earth. Understanding and modeling these motions can aid in the interpretation of imaged surface features that may exhibit signatures of constituent material properties. Also, upcoming sample-return missions to small bodies, and possible future manned missions, will involve interaction with the surface regolith, so it is important to develop tools to predict the surface response. We have added new capabilities to the parallelized N-body gravity tree code pkdgrav [1,2] that permit the simulation of granular dynamics, including multi-contact physics and friction forces, using the soft-sphere discrete-element method [3]. The numerical approach has been validated through comparison with laboratory experiments (e.g., [3,4]). Ongoing and recently completed projects include: impacts into granular materials using different projectile shapes [5]; possible tidal resurfacing of asteroid Apophis during its 2029 encounter [6]; the Brazil-nut effect in low gravity [7]; and avalanche modeling.Acknowledgements: DCR acknowledges NASA (grants NNX08AM39G, NNX10AQ01G, NNX12AG29G) and NSF (AST1009579). PM acknowledges the French agency CNES. SRS works on the NEOShield Project funded under the European Commission’s FP7 program agreement No. 282703. SM acknowledges support from the Center for Theory and Computation at U Maryland and the Dundee Fellowship at U Dundee. Most simulations were performed using the YORP cluster in the Dept. of Astronomy at U Maryland and on the Deepthought High-Performance Computing Cluster at U Maryland.References: [1] Richardson, D.C. et al. 2000, Icarus 143, 45; [2] Stadel, J. 2001, Ph.D. Thesis, U Washington; [3] Schwartz, S.R. et al. 2012, Gran

  2. Late effects from hadron therapy

    SciTech Connect

    Blakely, Eleanor A.; Chang, Polly Y.

    2004-06-01

    Successful cancer patient survival and local tumor control from hadron radiotherapy warrant a discussion of potential secondary late effects from the radiation. The study of late-appearing clinical effects from particle beams of protons, carbon, or heavier ions is a relatively new field with few data. However, new clinical information is available from pioneer hadron radiotherapy programs in the USA, Japan, Germany and Switzerland. This paper will review available data on late tissue effects from particle radiation exposures, and discuss its importance to the future of hadron therapy. Potential late radiation effects are associated with irradiated normal tissue volumes at risk that in many cases can be reduced with hadron therapy. However, normal tissues present within hadron treatment volumes can demonstrate enhanced responses compared to conventional modes of therapy. Late endpoints of concern include induction of secondary cancers, cataract, fibrosis, neurodegeneration, vascular damage, and immunological, endocrine and hereditary effects. Low-dose tissue effects at tumor margins need further study, and there is need for more acute molecular studies underlying late effects of hadron therapy.

  3. Aerofractures in Confined Granular Media

    NASA Astrophysics Data System (ADS)

    Eriksen, Fredrik K.; Turkaya, Semih; Toussaint, Renaud; Måløy, Knut J.; Flekkøy, Eirik G.

    2015-04-01

    We will present the optical analysis of experimental aerofractures in confined granular media. The study of this generic process may have applications in industries involving hydraulic fracturing of tight rocks, safe construction of dams, tunnels and mines, and in earth science where phenomena such as mud volcanoes and sand injectites are results of subsurface sediment displacements driven by fluid overpressure. It is also interesting to increase the understanding the flow instability itself, and how the fluid flow impacts the solid surrounding fractures and in the rest of the sample. Such processes where previously studied numerically [Niebling 2012a, Niebling 2012b] or in circular geometries. We will here explore experimentally linear geometries. We study the fracturing patterns that form when air flows into a dense, non-cohesive porous medium confined in a Hele-Shaw cell - i.e. into a packing of dry 80 micron beads placed between two glass plates separated by ~1mm. The cell is rectangular and fitted with a semi-permeable boundary to the atmosphere - blocking beads but not air - on one short edge, while the other three edges are impermeable. The porous medium is packed inside the cell between the semi-permeable boundary and an empty volume at the sealed side where the air pressure can be set and kept at a constant overpressure (1-2bar). Thus, for the air trapped inside the cell to release the overpressure it has to move through the solid. At high enough overpressures the air flow deforms the solid and increase permeability in some regions along the air-solid interface, which results in unstable flow and aerofracturing. Aerofractures are thought to be an analogue to hydrofractures, and an advantage of performing aerofracturing experiments in a Hele-Shaw cell is that the fracturing process can easily be observed in the lab. Our experiments are recorded with a high speed camera with a framerate of 1000 frames per second. In the analysis, by using various image

  4. Quantitative DEM of granular packings

    NASA Astrophysics Data System (ADS)

    Brodu, Nicolas; Dijksman, Joshua; Behringer, Robert

    2014-03-01

    We introduce a new model for simulating granular assemblies. This model explicitely accounts for the cross-influence of multiple contacts on grains. It maintains the surface deformations of the grains induced by the contacts, improving on the classical non-deformable interpenetrable spheres model, for a reasonable computational cost. We show that both multiple contacts and surface deformations are necessary for reproducing quantitatively the 3D force measurements we recently demonstrated. We also show that friction has a dramatic effect on the forces and number of contacts, so it cannot be ignored even for very small values. This work was funded by NASA grant NNX10AU01G, NSF grant DMR12-06351 and ARO grant W911NF-1-11-0110.

  5. Granular metamaterials for vibration mitigation

    NASA Astrophysics Data System (ADS)

    Gantzounis, G.; Serra-Garcia, M.; Homma, K.; Mendoza, J. M.; Daraio, C.

    2013-09-01

    Acoustic metamaterials that allow low-frequency band gaps are interesting for many practical engineering applications, where vibration control and sound insulation are necessary. In most prior studies, the mechanical response of these structures has been described using linear continuum approximations. In this work, we experimentally and theoretically address the formation of low-frequency band gaps in locally resonant granular crystals, where the dynamics of the system is governed by discrete equations. We investigate the quasi-linear behavior of such structures. The analysis shows that a stopband can be introduced at about one octave lower frequency than in materials without local resonances. Broadband and multi-frequency stopband characteristics can also be achieved by strategically tailoring the non-uniform local resonance parameters.

  6. 21 CFR 133.145 - Granular cheese for manufacturing.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Granular cheese for manufacturing. 133.145 Section... Standardized Cheese and Related Products § 133.145 Granular cheese for manufacturing. Granular cheese for manufacturing conforms to the definition and standard of identity prescribed for granular cheese by §...

  7. 21 CFR 133.145 - Granular cheese for manufacturing.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 2 2013-04-01 2013-04-01 false Granular cheese for manufacturing. 133.145 Section... Standardized Cheese and Related Products § 133.145 Granular cheese for manufacturing. Granular cheese for manufacturing conforms to the definition and standard of identity prescribed for granular cheese by §...

  8. 21 CFR 133.145 - Granular cheese for manufacturing.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Granular cheese for manufacturing. 133.145 Section... Standardized Cheese and Related Products § 133.145 Granular cheese for manufacturing. Granular cheese for manufacturing conforms to the definition and standard of identity prescribed for granular cheese by §...

  9. 21 CFR 133.145 - Granular cheese for manufacturing.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Granular cheese for manufacturing. 133.145 Section... Standardized Cheese and Related Products § 133.145 Granular cheese for manufacturing. Granular cheese for manufacturing conforms to the definition and standard of identity prescribed for granular cheese by §...

  10. 21 CFR 133.145 - Granular cheese for manufacturing.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Granular cheese for manufacturing. 133.145 Section... Standardized Cheese and Related Products § 133.145 Granular cheese for manufacturing. Granular cheese for manufacturing conforms to the definition and standard of identity prescribed for granular cheese by §...

  11. Force distributions in granular materials

    NASA Astrophysics Data System (ADS)

    Jaeger, Heinrich M.

    2002-03-01

    A fundamental problem in the study of disordered materials concerns the propagation of forces. Static granular media, such as sand particles inside a rigid container, have emerged as an important model system as they embody the zero temperature limit of disordered materials comprised of hardsphere repulsive particles. In this talk, I will review recent results on the distribution forces along the boundaries of granular material subjected to an applied load. While the spatial distribution of mean forces sensitively reflects the (macroscopic) packing structure of the material, the ensemble-averaged probability distribution of force fluctuations around the mean value, P(f), exhibits universal behavior. The shape of P(f) is found to be independent not only of the macroscopic packing arrangement but also of the inter-particle friction and, over a wide range, of the applied external stress. This shape is characterized by an exponential decay in the probability density for fluctuations above the mean force and only a small reduction, by no more than a factor two, for fluctuations below the mean [1]. Surprisingly, the exponential, non-Gaussian behavior appears to hold up even in the case of highly compressible grains, and it also has been observed in simulations of supercooled liquids [2]. I will discuss the implications of these findings on our current understanding of stress transmission in disordered media in general, and on glassy behavior in particular. [1] D. L. Blair, N. W. Mueggenburg, A. H. Marshall, H. M. Jaeger, and S. R. Nagel, Phys. Rev. E 63, 041304 (2001). [2] S. O’Hern, S. A. Langer, A. J. Liu, and S. R. Nagel, Phys. Rev. Lett. 86, 111 (2001). * Work performed in collaboration with D. L. Blair, J. M. Erikson, A. H. Marshall, N. W. Mueggenburg, and S. R. Nagel.

  12. Continuum description of avalanches in granular media.

    SciTech Connect

    Aranson, I. S.; Tsimring, L. S.

    2000-12-05

    A continuum theory of partially fluidized granular flows is proposed. The theory is based on a combination of the mass and momentum conservation equations with the order parameter equation which describes the transition between flowing and static components of the granular system. We apply this model to the dynamics of avalanches in chutes. The theory provides a quantitative description of recent observations of granular flows on rough inclined planes (Daerr and Douady 1999): layer bistability, and the transition from triangular avalanches propagating downhill at small inclination angles to balloon-shaped avalanches also propagating uphill for larger angles.

  13. Impact compaction of a granular material

    SciTech Connect

    Fenton, Gregg; Asay, Blaine; Dalton, Devon

    2015-05-19

    The dynamic behavior of granular materials has importance to a variety of engineering applications. Structural seismic coupling, planetary science, and earth penetration mechanics, are just a few of the application areas. Although the mechanical behavior of granular materials of various types have been studied extensively for several decades, the dynamic behavior of such materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This study will describe how an instrumented plunger impact system can be used to measure pressure-density relationships for model materials at high and controlled strain rates and subsequently used for computational modeling.

  14. Hadron particle theory

    SciTech Connect

    Alonso, J.R.

    1995-05-01

    Radiation therapy with ``hadrons`` (protons, neutrons, pions, ions) has accrued a 55-year track record, with by now over 30,000 patients having received treatments with one of these particles. Very good, and in some cases spectacular results are leading to growth in the field in specific well-defined directions. The most noted contributor to success has been the ability to better define and control the radiation field produced with these particles, to increase the dose delivered to the treatment volume while achieving a high degree of sparing of normal tissue. An additional benefit is the highly-ionizing, character of certain beams, leading to creater cell-killing potential for tumor lines that have historically been very resistant to radiation treatments. Until recently these treatments have been delivered in laboratories and research centers whose primary, or original mission was physics research. With maturity in the field has come both the desire to provide beam facilities more accessible to the clinical setting, of a hospital, as well as achieving, highly-efficient, reliable and economical accelerator and beam-delivery systems that can make maximum advantage of the physical characteristics of these particle beams. Considerable work in technology development is now leading, to the implementation of many of these ideas, and a new generation of clinically-oriented facilities is beginning to appear. We will discuss both the physical, clinical and technological considerations that are driving these designs, as well as highlighting, specific examples of new facilities that are either now treating, patients or that will be doing so in the near future.

  15. Identifying Multiquark Hadrons from Heavy Ion Collisions

    SciTech Connect

    Cho, Sungtae; Furumoto, Takenori; Yazaki, Koichi; Hyodo, Tetsuo; Jido, Daisuke; Ohnishi, Akira; Ko, Che Ming; Lee, Su Houng; Nielsen, Marina; Sekihara, Takayasu; Yasui, Shigehiro

    2011-05-27

    Identifying hadronic molecular states and/or hadrons with multiquark components either with or without exotic quantum numbers is a long-standing challenge in hadronic physics. We suggest that studying the production of these hadrons in relativistic heavy ion collisions offers a promising resolution to this problem as yields of exotic hadrons are expected to be strongly affected by their structures. Using the coalescence model for hadron production, we find that, compared to the case of a nonexotic hadron with normal quark numbers, the yield of an exotic hadron is typically an order of magnitude smaller when it is a compact multiquark state and a factor of 2 or more larger when it is a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured in these experiments.

  16. Capillary Movement in Granular Beds in Microgravity

    NASA Technical Reports Server (NTRS)

    Yendler, Boris S.; Bula, Ray J.; Kliss, Mark (Technical Monitor)

    1996-01-01

    Understanding the dynamics of capillary flow through unsaturated porous media is very important for the development of an effective water and nutrient delivery system for growing plants in microgravity and chemical engineering applications. Experiments were conducted on the Space Shuttle during the STS-63 mission using three experimental cuvettes called "Capillary Testbed-M." These experiments studied the effect of bead diameter on capillary flow by comparing the capillary flow in three different granular beds. It was observed that the speed of water propagation in the granular bed consisting of 1.5 mm diameter particles was less than that in the bed consisting of 1.0 mm. diameter particles. Such results contradict the existing theory of capillary water propagation in granular beds. It was found also that in microgravity water propagates independently in adjacent layers of a layered granular bed .

  17. Mechanisms for slow strengthening in granular materials

    PubMed

    Losert; Geminard; Nasuno; Gollub

    2000-04-01

    Several mechanisms cause a granular material to strengthen over time at low applied stress. The strength is determined from the maximum frictional force F(max) experienced by a shearing plate in contact with wet or dry granular material after the layer has been at rest for a waiting time tau. The layer strength increases roughly logarithmically with tau only if a shear stress is applied during the waiting time. The mechanisms of strengthening are investigated by sensitive displacement measurements, and by imaging of particle motion in the shear zone. Granular matter can strengthen due to a slow shift in the particle arrangement under shear stress. Humidity also leads to strengthening, but is found not to be its sole cause. In addition to these time dependent effects, the static friction coefficient can also be increased by compaction of the granular material under some circumstances, and by a cycling of the applied shear stress. PMID:11088198

  18. NMR Measurements of Granular Flow and Compaction

    NASA Astrophysics Data System (ADS)

    Fukushima, Eiichi

    1998-03-01

    Nuclear magnetic resonance (NMR) can be used to measure statistical distributions of granular flow velocity and fluctuations of velocity, as well as spatial distributions of particulate concentration, flow velocity, its fluctuations, and other parameters that may be derived from these. All measurements have been of protons in liquid-containing particles such as mustard seeds or pharmaceutical pills. Our favorite geometry has been the slowly rotating partially filled rotating drum with granular flow taking place along the free surface of the particles. All the above-mentioned parameters have been studied as well as a spatial distribution of particulate diffusion coefficients, energy dissipation due to collisions, as well as segregation of non-uniform mixtures of granular material. Finally, we describe some motions of granular material under periodic vibrations.

  19. Tunable magneto-granular phononic crystals

    NASA Astrophysics Data System (ADS)

    Allein, F.; Tournat, V.; Gusev, V. E.; Theocharis, G.

    2016-04-01

    This paper reports on the study of the dynamics of 1D magneto-granular phononic crystals composed of a chain of spherical steel beads inside a properly designed magnetic field. This field is induced by an array of permanent magnets, located in a holder at a given distance from the chain. The theoretical and experimental results of the band gap structure are displayed, including all six degrees of freedom for the beads, i.e., three translations and three rotations. Experimental evidence of transverse-rotational modes of propagation is presented; moreover, by changing the strength of the magnetic field, the dynamic response of the granular chain is tuned. The combination of non-contact tunability with the potentially strong nonlinear behavior of granular systems ensures the suitability of magneto-granular phononic crystals as nonlinear, tunable mechanical metamaterials for use in controlling elastic wave propagation.

  20. Granular crystals: Nonlinear dynamics meets materials engineering

    SciTech Connect

    Porter, Mason A.; Kevrekidis, Panayotis G.; Daraio, Chiara

    2015-11-01

    In this article, the freedom to choose the size, stiffness, and spatial distribution of macroscopic particles in a lattice makes granular crystals easily tailored building blocks for shock-absorbing materials, sound-focusing devices, acoustic switches, and other exotica.

  1. Acoustical properties of double porosity granular materials.

    PubMed

    Venegas, Rodolfo; Umnova, Olga

    2011-11-01

    Granular materials have been conventionally used for acoustic treatment due to their sound absorptive and sound insulating properties. An emerging field is the study of the acoustical properties of multiscale porous materials. An example of these is a granular material in which the particles are porous. In this paper, analytical and hybrid analytical-numerical models describing the acoustical properties of these materials are introduced. Image processing techniques have been employed to estimate characteristic dimensions of the materials. The model predictions are compared with measurements on expanded perlite and activated carbon showing satisfactory agreement. It is concluded that a double porosity granular material exhibits greater low-frequency sound absorption at reduced weight compared to a solid-grain granular material with similar mesoscopic characteristics. PMID:22087905

  2. QCD thermodynamics and missing hadron states

    NASA Astrophysics Data System (ADS)

    Petreczky, Peter

    2016-03-01

    Equation of State and fluctuations of conserved charges in hot strongly interacting matter are being calculated with increasing accuracy in lattice QCD, and continuum results at physical quark masses become available. At sufficiently low temperature the thermodynamic quantities can be understood in terms of hadron resonance gas model that includes known hadrons and hadronic resonances from Particle Data Book. However, for some quantities it is necessary to include undiscovered hadronic resonances (missing states) that are, however, predicted by quark model and lattice QCD study of hadron spectrum. Thus, QCD thermodynamics can provide indications for the existence of yet undiscovered hadron states.

  3. Rheology of weakly vibrated granular materials

    NASA Astrophysics Data System (ADS)

    Dijksman, J. A.; Wortel, G.; van Hecke, M.

    2009-06-01

    We show how weak vibrations substantially modify the rheology of granular materials. We experimentally probe dry granular flows in a weakly vibrated split bottom shear cell—the weak vibrations modulate gravity and act as an agitation source. By tuning the applied stress and vibration strength, and monitoring the resulting strain as a function of time, we uncover a rich phase diagram in which non-trivial transitions separate a jammed phase, a creep flow case, and a steady flow case.

  4. Rheology of weakly vibrated granular media

    NASA Astrophysics Data System (ADS)

    Wortel, Geert H.; Dijksman, Joshua A.; van Hecke, Martin

    2014-01-01

    We probe the rheology of weakly vibrated granular flows as function of flow rate, vibration strength, and pressure by performing experiments in a vertically vibrated split-bottom shear cell. For slow flows, we establish the existence of a vibration-dominated granular flow regime, where the driving stresses smoothly vanish as the driving rate is diminished. We distinguish three qualitatively different vibration-dominated rheologies, most strikingly a regime where the shear stresses no longer are proportional to the pressure.

  5. Shear dispersion in dense granular flows

    DOE PAGESBeta

    Christov, Ivan C.; Stone, Howard A.

    2014-04-18

    We formulate and solve a model problem of dispersion of dense granular materials in rapid shear flow down an incline. The effective dispersivity of the depth-averaged concentration of the dispersing powder is shown to vary as the Péclet number squared, as in classical Taylor–Aris dispersion of molecular solutes. An extension to generic shear profiles is presented, and possible applications to industrial and geological granular flows are noted.

  6. Granular Cell Tumor: An Uncommon Benign Neoplasm

    PubMed Central

    Gayen, Tirthankar; Das, Anupam; Shome, Kaushik; Bandyopadhyay, Debabrata; Das, Dipti; Saha, Abanti

    2015-01-01

    Granular cell tumor is a distinctly rare neoplasm of neural sheath origin. It mainly presents as a solitary asymptomatic swelling in the oral cavity, skin, and rarely internal organs in the middle age. Histopathology is characteristic, showing polyhedral cells containing numerous fine eosinophilic granules with indistinct cell margins. We present a case of granular cell tumor on the back of a 48-year-old woman which was painful, mimicking an adnexal tumor. PMID:26120181

  7. Aerobic granular processes: Current research trends.

    PubMed

    Zhang, Quanguo; Hu, Jianjun; Lee, Duu-Jong

    2016-06-01

    Aerobic granules are large biological aggregates with compact interiors that can be used in efficient wastewater treatment. This mini-review presents new researches on the development of aerobic granular processes, extended treatments for complicated pollutants, granulation mechanisms and enhancements of granule stability in long-term operation or storage, and the reuse of waste biomass as renewable resources. A discussion on the challenges of, and prospects for, the commercialization of aerobic granular process is provided. PMID:26873285

  8. Contact micromechanics in granular media with clay

    SciTech Connect

    Ita, S.L.

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  9. Impact phenomena in fluidized granular matter

    NASA Astrophysics Data System (ADS)

    Mayor, Patrick; Katsuragi, Hiroaki; Durian, Douglas

    2009-03-01

    Projectiles dropped into granular media form a crater and come to rest in a particular way that has been actively investigated in numerous studies. These impact phenomena illustrate how particulate materials respond to externally applied forces. Several recent experiments have focused on the penetration of projectiles impacting granular materials at relatively low speeds, and measured the dynamics of the impact process, yielding force laws accounting for the observations. We present results showing how granular impacts are affected when the load on the grains is modified using a vertical gas flow. Balls or cylinders are dropped into a dry, noncohesive granular medium and we measure the penetration depth when gas is flown upward (thus unloading the contacts) or downward (loading the contacts). We observe that the frictional drag decreases linearly with the flow rate, and vanishes completely once the system is fluidized. Different projectile geometries allow us to separate the effect of normal and tangential frictional forces. We also consider the case of objects that are lowered quasistatically into the granular medium and measure the net vertical force exerted by the granular system on the objects at each immersion depth. We then discuss how this resistance force compares with the forces observed in actual impacts experiments.

  10. Steady flow dynamics during granular impact

    NASA Astrophysics Data System (ADS)

    Clark, Abram H.; Kondic, Lou; Behringer, Robert P.

    2016-05-01

    We study experimentally and computationally the dynamics of granular flow during impacts where intruders strike a collection of disks from above. In the regime where granular force dynamics are much more rapid than the intruder motion, we find that the particle flow near the intruder is proportional to the instantaneous intruder speed; it is essentially constant when normalized by that speed. The granular flow is nearly divergence free and remains in balance with the intruder, despite the latter's rapid deceleration. Simulations indicate that this observation is insensitive to grain properties, which can be explained by the separation of time scales between intergrain force dynamics and intruder dynamics. Assuming there is a comparable separation of time scales, we expect that our results are applicable to a broad class of dynamic or transient granular flows. Our results suggest that descriptions of static-in-time granular flows might be extended or modified to describe these dynamic flows. Additionally, we find that accurate grain-grain interactions are not necessary to correctly capture the granular flow in this regime.

  11. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32{sup 3} {times} 64 lattice volume at {beta} = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the {triangle} masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  12. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong.

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32[sup 3] [times] 64 lattice volume at [beta] = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the [triangle] masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  13. Hadronic EDMs in SUSY GUTs

    SciTech Connect

    Kakizaki, Mitsuru

    2005-12-02

    We investigate the constraints from the null results of the hadronic electric dipole moment (EDM) searches on supersymmetric grand unified theories (SUSY GUTs). Especially we focus on (i) SUSY SU(5) GUTs with right-handed neutrinos and (ii) orbifold GUTs, where the GUT symmetry and SUSY are both broken by boundary conditions in the compactified extra dimensions. We demonstrate that the hadronic EDM experiments severely constrain SUSY GUT models. The interplay between future EDM and LFV experiments will probe the structures of the GUTs and the SUSY breaking mediation mechanism.

  14. Microfluidics of soft granular gels

    NASA Astrophysics Data System (ADS)

    Nixon, Ryan; Bhattacharjee, Tapomoy; Sawyer, W. Gregory; Angelini, Thomas E.

    Microfluidic methods for encapsulating cells and particles typically involve drop making with two immiscible fluids. The main materials constraint in this approach is surface tension, creating inherent instability between the two fluids. We can eliminate this instability by using miscible inner and outer phases. This is achieved by using granular micro gels which are chemically miscible but physically do not mix. These microgels are yield stress materials, so they flow as solid plugs far from shear gradients, and fluidize where gradients are generated - near an injection nozzle for example. We have found that tuning the yield stress of the material by varying polymer concentration, device performance can be controlled. The solid like behavior of the gel allows us to produces infinitely stable jets that maintain their integrity and configuration over long distances and times. These properties can be combined and manipulated to produce discrete particulate bunches of an inner phase, flowing inside of an outer phase, well enough even to print a Morse code message suspended within flow chambers about a millimeter in diameter moving at millimeters a second.

  15. Vortices in vibrated granular rods

    NASA Astrophysics Data System (ADS)

    Neicu, Toni; Kudrolli, Arshad

    2002-03-01

    We report the first experimental observation of vortex patterns in granular rods inside a container that is vibrated vertically . The experiments were carried out with an anodized aluminum circular container which is rigidly attached to an electromagnetic shaker and the patterns are imaged using a high-frame rate digital camera. At low rod numbers and driving amplitudes, the rods are observed to lie horizontally. Above a critical number or packing fraction of rods, moving domains of vertical rods are spontaneously observed to form which coexist with horizontal rods. These small domains of vertical rods coarsen over time to form a few large vortices. The size of the vortices increases with the number of rods. We are able to track the ends of the vertical rods and obtain the velocity fields of the vortices. The mean azimuthal velocity as a function of distance from the center of the vortex is obtained as a function of the packing fraction. We will report the phase diagram of the various patterns observed as function of number of rods and driving amplitude. The mechanism for the formation and motion of the domains of vertical rods will be also discussed.

  16. Shear jamming in granular materials

    NASA Astrophysics Data System (ADS)

    Zhang, Jie

    2013-03-01

    For frictionless particles with purely repulsive interactions, there is a critical packing fraction ϕJ below which no jammed states exist. Frictional granular particles in the regime of ϕ <ϕJ act differently under shear: early experiments by Zhang & Behringer at Duke University show jammed states can be created by the application of shear stress. Compared to the states above ϕJ, the shear-jammed states (SJS) are mechanically more fragile, but they can resist shear. Formation of these states requires the anisotropic contact network as a backbone and these new states must be incorporated into a more general jamming picture (Bi et al Nature 2011). If time permits, I will present some new results from recent experiments at SJTU aimed towards understanding the more detailed nature of SJS and the transition from unjammed states to SJS. This work is in collaboration with Bob Behringer at Duke University, Dapeng Bi (now at Syracuse) and Bulbul Chakraborty at Brandeis University. The work at SJTU is in collaboration with Ling Zhang and several undergrads in the physics department.

  17. Mechanics of Granular Materials (MGM)

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The packing of particles can change radically during cyclic loading such as in an earthquake or when shaking a container to compact a powder. A large hole (1) is maintained by the particles sticking to each other. A small, counterclockwise strain (2) collapses the hole, and another large strain (3) forms more new holes which collapse when the strain reverses (4). Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. MGM experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (after T.L. Youd, Packing Changes and Liquefaction Susceptibility, Journal of the Geotechnical Engieering Division, 103: GT8,918-922, 1977)(Credit: NASA/Marshall Space Flight Center.)(Credit: University of Colorado at Boulder).

  18. Smarticles: smart, active granular matter

    NASA Astrophysics Data System (ADS)

    Savoie, Will; Pazouki, Arman; Negrut, Dan; Goldman, Daniel

    We investigate a granular medium composed of smart, active particles, or ``smarticles''. Previously, we discovered that ensembles of ``u''-shaped particles exhibited geometrically-induced cohesion by mechanically entangling via particle interpenetration [Gravish et al., PRL, 2012]; the strength and/or extent of entanglement could be varied by changing particle level entanglement by changes in arm-to-base length of the u-particle. Since changing this parameter on demand is inconvenient, we develop a power-autonomous programmable robot composed of two motors and three links with an on-board microcontroller. This smarticle can be activated to change its configuration (specified by its two joint angles) through audio communication. To complement these experiments, since study large ensembles of smarticles is cost and labor prohibitive, we also develop a simulated smarticle in the Chrono multibody simulation environment. We systematically study ensemble cohesiveness and compaction as a function of shape changes of the smarticles. We find that suitable activation of smarticles allows ensembles to become cohesive to ``grip'' rigid objects and lose cohesion to release on command. Work supported by ARO.

  19. Chemotaxis of large granular lymphocytes

    SciTech Connect

    Pohajdak, B.; Gomez, J.; Orr, F.W.; Khalil, N.; Talgoy, M.; Greenberg, A.H.

    1986-01-01

    The hypothesis that large granular lymphocytes (LGL) are capable of directed locomotion (chemotaxis) was tested. A population of LGL isolated from discontinuous Percoll gradients migrated along concentration gradients of N-formyl-methionyl-leucyl-phenylalanine (f-MLP), casein, and C5a, well known chemoattractants for polymorphonuclear leukocytes and monocytes, as well as interferon-..beta.. and colony-stimulating factor. Interleukin 2, tuftsin, platelet-derived growth factor, and fibronectin were inactive. Migratory responses were greater in Percoll fractions with the highest lytic activity and HNK-1/sup +/ cells. The chemotactic response to f-MLP, casein, and C5a was always greater when the chemoattractant was present in greater concentration in the lower compartment of the Boyden chamber. Optimum chemotaxis was observed after a 1 hr incubation that made use of 12 ..mu..m nitrocellulose filters. LGL exhibited a high degree of nondirected locomotion when allowed to migrate for longer periods (> 2 hr), and when cultured in vitro for 24 to 72 hr in the presence or absence of IL 2 containing phytohemagluttinin-conditioned medium. LGL chemotaxis to f-MLP could be inhibited in a dose-dependent manner by the inactive structural analog CBZ-phe-met, and the RNK tumor line specifically bound f-ML(/sup 3/H)P, suggesting that LGL bear receptors for the chemotactic peptide.

  20. Discrete Element Modeling of Complex Granular Flows

    NASA Astrophysics Data System (ADS)

    Movshovitz, N.; Asphaug, E. I.

    2010-12-01

    Granular materials occur almost everywhere in nature, and are actively studied in many fields of research, from food industry to planetary science. One approach to the study of granular media, the continuum approach, attempts to find a constitutive law that determines the material's flow, or strain, under applied stress. The main difficulty with this approach is that granular systems exhibit different behavior under different conditions, behaving at times as an elastic solid (e.g. pile of sand), at times as a viscous fluid (e.g. when poured), or even as a gas (e.g. when shaken). Even if all these physics are accounted for, numerical implementation is made difficult by the wide and often discontinuous ranges in continuum density and sound speed. A different approach is Discrete Element Modeling (DEM). Here the goal is to directly model every grain in the system as a rigid body subject to various body and surface forces. The advantage of this method is that it treats all of the above regimes in the same way, and can easily deal with a system moving back and forth between regimes. But as a granular system typically contains a multitude of individual grains, the direct integration of the system can be very computationally expensive. For this reason most DEM codes are limited to spherical grains of uniform size. However, spherical grains often cannot replicate the behavior of real world granular systems. A simple pile of spherical grains, for example, relies on static friction alone to keep its shape, while in reality a pile of irregular grains can maintain a much steeper angle by interlocking force chains. In the present study we employ a commercial DEM, nVidia's PhysX Engine, originally designed for the game and animation industry, to simulate complex granular flows with irregular, non-spherical grains. This engine runs as a multi threaded process and can be GPU accelerated. We demonstrate the code's ability to physically model granular materials in the three regimes

  1. Physics at hadron colliders: Experimental view

    SciTech Connect

    Siegrist, J.L.

    1987-08-01

    The physics of the hadron-hadron collider experiment is considered from an experimental point of view. The problems encountered in determination of how well the standard model describes collider results are discussed. 53 refs., 58 figs.

  2. Quark-Hadron Duality in Electron Scattering

    SciTech Connect

    W. Melnitchouk

    2000-09-01

    Quark-hadron duality addresses some of the most fundamental issues in strong interaction physics, in particular the nature of the transition from the perturbative to non-perturbative regions of QCD. I summarize recent developments in quark-hadron duality in lepton-hadron scattering, and outline how duality can be studied at future high-luminosity facilities such as Jefferson Lab at 12 GeV, or an electron-hadron collider such as EPIC.

  3. Numerical calculation of granular entropy: counting the uncountable

    NASA Astrophysics Data System (ADS)

    Frenkel, Daan

    In 1989, Sir Sam Edwards introduced the concept of `granular entropy', defined as the logarithm of the number of distinct packings of N granular particles in a fixed volume V. The proposal was rather controversial but much of the debate was sterile because the granular entropy could not even be computed for systems as small as 20 particles - hardly a good approximation of the thermodynamic limit. In my talk I will describe how granular entropies of much larger systems can now be computed, using a novel algorithm. Interestingly, it turns out the definition of granular entropy will have to be modified to guarantee that granular entropy is extensive.

  4. Dimensional Reduction and Hadronic Processes

    SciTech Connect

    Signer, Adrian; Stoeckinger, Dominik

    2008-11-23

    We consider the application of regularization by dimensional reduction to NLO corrections of hadronic processes. The general collinear singularity structure is discussed, the origin of the regularization-scheme dependence is identified and transition rules to other regularization schemes are derived.

  5. Hadron Spectroscopy at Jefferson Laboratory

    SciTech Connect

    Dennis P. Weygand

    2004-08-01

    Recent results on hadron spectroscopy from Jefferson Laboratory's CEBAF Large Acceptance Spectrometer (CLAS) are presented. In particular we present results from the baryon resonance program for both electro- and photo- production. Also, we present very preliminary results on meson spectroscopy in p interactions, and new results on the observation of the exotic baryon, the Theta +.

  6. B physics at hadron colliders

    SciTech Connect

    Butler, J.N.; /Fermilab

    2005-09-01

    This paper discusses the physics opportunity and challenges for doing high precision B physics experiments at hadron colliders. It describes how these challenges have been addressed by the two currently operating experiments, CDF and D0, and how they are addressed by three experiments, ATLAS, CMS, and LHCb, at the LHC.

  7. The very large hadron collider

    SciTech Connect

    1998-09-01

    This paper reviews the purposes to be served by a very large hadron collider and the organization and coordination of efforts to bring it about. There is some discussion of magnet requirements and R&D and the suitability of the Fermilab site.

  8. Key Issues in Hadronic Physics

    SciTech Connect

    Simon Capstick; et. Al.

    2000-12-01

    A group of fifty physicists met in Duck, NC, Nov. 6-9 to discuss the current status and future goals of hadronic physics. The main purpose of the meeting was to define the field by identifying its key issues, challenges, and opportunities. The conclusions, incorporating considerable input from the community at large, are presented in this white paper.

  9. CERN's Large Hadron Collider project

    NASA Astrophysics Data System (ADS)

    Fearnley, Tom A.

    1997-03-01

    The paper gives a brief overview of CERN's Large Hadron Collider (LHC) project. After an outline of the physics motivation, we describe the LHC machine, interaction rates, experimental challenges, and some important physics channels to be studied. Finally we discuss the four experiments planned at the LHC: ATLAS, CMS, ALICE and LHC-B.

  10. Future hadron physics at Fermilab

    SciTech Connect

    Appel, Jeffrey A.; /Fermilab

    2005-09-01

    Today, hadron physics research occurs at Fermilab as parts of broader experimental programs. This is very likely to be the case in the future. Thus, much of this presentation focuses on our vision of that future--a future aimed at making Fermilab the host laboratory for the International Linear Collider (ILC). Given the uncertainties associated with the ILC--the level of needed R&D, the ILC costs, and the timing--Fermilab is also preparing for other program choices. I will describe these latter efforts, efforts focused on a Proton Driver to increase the numbers of protons available for experiments. As examples of the hadron physics which will be coming from Fermilab, I summarize three experiments: MIPP/E907 which is running currently, and MINERvA and Drell-Yan/E906 which are scheduled for future running periods. Hadron physics coming from the Tevatron Collider program will be summarized by Arthur Maciel in another talk at Hadron05.

  11. Theoretical predictions for exotic hadrons

    SciTech Connect

    Barnes, T. |

    1996-12-31

    In this contribution the authors discuss current theoretical expectations for the properties of light meson exotica, which are meson resonances outside the q{anti q} quark model. Specifically they discuss expectations for gluonic hadrons (glueballs and hybrids) and multiquark systems (molecules). Experimental candidates for these states are summarized, and the relevance of a TCF to these studies is stressed.

  12. Hadronic Interactions from Lattice QCD

    SciTech Connect

    Konstantinos Orginos

    2006-03-19

    In this talk I discuss a few recent results on lattice calculations of scattering lengths in hadronic processes. In particular, I present the scattering length of the pion-pion scattering in the I=2 channel and the nucleon-nucleon {sup 1}S{sub 0} channel and {sup 3}S{sub 1}-{sup 3}D{sub 1} coupled channels.

  13. Composite leptoquarks in hadronic colliders

    SciTech Connect

    Eboli, O.J.P.; Olinto, A.V.

    1988-12-01

    We study the production of composite scalar leptoquarks in hadronic colliders (CERN p-barp, Fermilab Tevatron p-barp, and the Superconducting Super Collider pp). We examine its direct single production via qg..-->..l+leptoquark, and its effect on the production of lepton pairs (p/sup (-)/p..-->..l/sup +/l/sup -/).

  14. The CMS central hadron calorimeter

    SciTech Connect

    Freeman, J.; E892 Collaboration

    1996-12-31

    The CMS central hadron calorimeter is a copper absorber/ scintillator sampling structure. We describe design choices that led us to this concept, details of the mechanical and optical structure, and test beam results. We discuss calibration techniques, and finally the anticipated construction schedule.

  15. Anomalous correlation between hadron and electromagnetic particles in hadron and gamma-ray families

    NASA Technical Reports Server (NTRS)

    Tamada, M.

    1985-01-01

    Correlations between hadrons and electromagnetic particles were studied in the hadron-gamma families observed in the Chacaltaya emulsion chamber experiment. It is found that there exist a number of hadrons which associate electromagnetic showers in extraordinarily close vicinity. The probability to have such a large number of hadrons associating electromagnetic showers, expected from background calculation, is found to be negligibly small and it means there exists anomalous correlation between hadrons and electromagnetic particles in the characteristic spread of atmospheric electromagnetic cascade.

  16. Granular Materials and Risks in ISRU

    NASA Technical Reports Server (NTRS)

    Behringer, Robert P.; Wilki8nson, R. Allen

    2004-01-01

    Working with soil, sand, powders, ores, cement and sintered bricks, excavating, grading construction sites, driving off-road, transporting granules in chutes and pipes, sifting gravel, separating solids from gases, and using hoppers are so routine that it seems straightforward to execute these operations on the Moon and Mars as we do on Earth. We discuss how little these processes are understood and point out the nature of trial-and-error practices that are used in today s massive over-design. Nevertheless, such designs have a high failure rate. Implementation and extensive incremental scaling up of industrial processes are routine because of the inadequate predictive tools for design. We present a number of pragmatic scenarios where granular materials play a role, the risks involved, what some of the basic issues are, and what understanding is needed to greatly reduce the risks. This talk will focus on a particular class of granular flow issues, those that pertain to dense materials, their physics, and the failure problems associated with them. In particular, key issues where basic predictability is lacking include stability of soils for the support of vehicles and facilities, ability to control the flow of dense materials (jamming and flooding/unjamming at the wrong time), the ability to predict stress profiles (hence create reliable designs) for containers such as bunkers or silos. In particular, stress fluctuations, which are not accounted for in standard granular design models, can be very large as granular materials flows, and one result is frequent catastrophic failure of granular devices.

  17. Granular Materials and Risks In ISRU

    NASA Technical Reports Server (NTRS)

    Behringer, Robert P.; Wilkinson, R. Allen

    2004-01-01

    Working with soil, sand, powders, ores, cement and sintered bricks, excavating, grading construction sites, driving off-road, transporting granules in chutes and pipes, sifting gravel, separating solids from gases, and using hoppers are so routine that it seems straightforward to execute these operations on the Moon and Mars as we do on Earth. We discuss how little these processes are understood and point out the nature of trial-and-error practices that are used in today's massive over-design. Nevertheless, such designs have a high failure rate. Implementation and extensive incremental scaling up of industrial processes are routine because of the inadequate predictive tools for design. We present a number of pragmatic scenarios where granular materials play a role, the risks involved, what some of the basic issues are, and what understanding is needed to greatly reduce the risks. This talk will focus on a particular class of granular flow issues, those that pertain to dense materials, their physics, and the failure problems associated with them. In particular, key issues where basic predictability is lacking include stability of soils for the support of vehicles and facilities, ability to control the flow of dense materials (jamming and flooding/unjamming at the wrong time), the ability to predict stress profiles (hence create reliable designs) for containers such as bunkers or silos. In particular, stress fluctuations, which are not accounted for in standard granular design models, can be very large as granular materials flows, and one result is frequent catastrophic failure of granular devices.

  18. Characteristics of undulatory locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn J.

    2016-03-01

    Undulatory locomotion is ubiquitous in nature and observed in different media, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Despite the similarity in the undulating pattern, the swimming characteristics depend on the rheological properties of different media. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but recently a resistive force theory in granular media has been proposed and shown useful in studying the locomotion of a sand-swimming lizard. Here we employ the proposed model to investigate the swimming characteristics of a slender filament, of both finite and infinite length, undulating in a granular medium and compare the results with swimming in viscous fluids. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. We also find that, similar to Lighthill's results using resistive force theory in viscous fluids, the sawtooth swimmer is the optimal waveform for propulsion speed at a given power consumption in granular media. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  19. Plastic deformation in a metallic granular chain

    NASA Astrophysics Data System (ADS)

    Musson, Ryan W.; Carlson, William

    2016-03-01

    Solitary wave response was investigated in a metallic granular chain-piston system using LS-DYNA. A power law hardening material model was used to show that localized plastic deformation is present in a metallic granular chain for an impact velocity of 0.5 m/s. This loss due to plastic deformation was quantified via impulse, and it was shown that the loss scales nearly linearly with impact velocity. Therefore, metallic grains may not be suitable for devices that require high-amplitude solitary waves. There would be too much energy lost to plastic deformation. One can assume that ceramics will behave elastically; therefore, the response of an aluminum oxide granular chain was compared to that of a steel chain.

  20. Convection in vibrated annular granular beds

    NASA Astrophysics Data System (ADS)

    Wildman, R. D.; Martin, T. W.; Krouskop, P. E.; Talbot, J.; Huntley, J. M.; Parker, D. J.

    2005-06-01

    The response to vibration of a granular bed, consisting of a standard cylindrical geometry but with the addition of a dissipative cylindrical inner wall, has been investigated both experimentally (using positron emission particle tracking) and numerically (using hard sphere molecular dynamics simulation). The packing fraction profiles and granular temperature distributions (in both vertical and horizontal directions) were determined as a function of height and distance from the axis. The two sets of results were in reasonable agreement. The molecular dynamics simulations were used to explore the behavior of the granular bed in the inner wall-outer wall coefficient of restitution phase space. It was observed that one could control the direction of the toroidal convection rolls by manipulating the relative dissipation at the inner and outer walls via the coefficients of restitution, and with several layers of grains it was seen that double convection rolls could also be formed, a result that was subsequently confirmed experimentally.

  1. Unsteady granular flows down an inclined plane.

    PubMed

    Parez, Stanislav; Aharonov, Einat; Toussaint, Renaud

    2016-04-01

    The continuum description of granular flows is still a challenge despite their importance in many geophysical and industrial applications. We extend previous works, which have explored steady flow properties, by focusing on unsteady flows accelerating or decelerating down an inclined plane in the simple shear configuration. We solve the flow kinematics analytically, including predictions of evolving velocity and stress profiles and the duration of the transient stage. The solution shows why and how granular materials reach steady flow on slopes steeper than the angle of repose and how they decelerate on shallower slopes. The model might facilitate development of natural hazard assessment and may be modified in the future to explore unsteady granular flows in different configurations. PMID:27176375

  2. Unsteady granular flows down an inclined plane

    NASA Astrophysics Data System (ADS)

    Parez, Stanislav; Aharonov, Einat; Toussaint, Renaud

    2016-04-01

    The continuum description of granular flows is still a challenge despite their importance in many geophysical and industrial applications. We extend previous works, which have explored steady flow properties, by focusing on unsteady flows accelerating or decelerating down an inclined plane in the simple shear configuration. We solve the flow kinematics analytically, including predictions of evolving velocity and stress profiles and the duration of the transient stage. The solution shows why and how granular materials reach steady flow on slopes steeper than the angle of repose and how they decelerate on shallower slopes. The model might facilitate development of natural hazard assessment and may be modified in the future to explore unsteady granular flows in different configurations.

  3. Statistical mechanics of dense granular media

    NASA Astrophysics Data System (ADS)

    Nicodemi, M.; Coniglio, A.; de Candia, A.; Fierro, A.; Ciamarra, M. Pica; Tarzia, M.

    2005-12-01

    We discuss some recent results on Statistical Mechanics approach to dense granular media. In particular, by analytical mean field investigation we derive the phase diagram of monodisperse and bydisperse granular assemblies. We show that "jamming" corresponds to a phase transition from a "fluid" to a "glassy" phase, observed when crystallization is avoided. The nature of such a "glassy" phase turns out to be the same found in mean field models for glass formers. This gives quantitative evidence to the idea of a unified description of the "jamming" transition in granular media and thermal systems, such as glasses. We also discuss mixing/segregation transitions in binary mixtures and their connections to phase separation and "geometric" effects.

  4. Statistical mechanics of dense granular media

    NASA Astrophysics Data System (ADS)

    Coniglio, A.; Fierro, A.; Nicodemi, M.; Pica Ciamarra, M.; Tarzia, M.

    2005-06-01

    We discuss some recent results on the statistical mechanics approach to dense granular media. In particular, by analytical mean field investigation we derive the phase diagram of monodisperse and bidisperse granular assemblies. We show that 'jamming' corresponds to a phase transition from a 'fluid' to a 'glassy' phase, observed when crystallization is avoided. The nature of such a 'glassy' phase turns out to be the same as found in mean field models for glass formers. This gives quantitative evidence for the idea of a unified description of the 'jamming' transition in granular media and thermal systems, such as glasses. We also discuss mixing/segregation transitions in binary mixtures and their connections to phase separation and 'geometric' effects.

  5. Creep and aging in jammed granular materials

    NASA Astrophysics Data System (ADS)

    Srivastava, Ishan; Fisher, Timothy

    Granular materials flow (or unjam) when stressed above the Coulomb yield stress, but a slow creep is observed when the applied stresses are low. In this work, using a recently introduced enthalpy-based variable-cell simulation method, we will present results on the creep and slow aging dynamics in granular systems comprised of soft particles of varying shape that are hydrostatically jammed and subjected to an external stress. We observe a two-stage creep with an initial fast exponential evolution followed by a slow logarithmic evolution over long time scales. We correlate the slow creeping dynamics with micromechanical evolution at the grain scale, such as increasing dynamical heterogeneity and force-chain rearrangements. Results will also be presented on the effect of grain shape (faceted vs. spherical) on the creep and aging dynamics. Finally, a continuum granular fluidity model is developed to rationalize these observations.

  6. Impact compaction of a granular material

    DOE PAGESBeta

    Fenton, Gregg; Asay, Blaine; Dalton, Devon

    2015-05-19

    The dynamic behavior of granular materials has importance to a variety of engineering applications. Structural seismic coupling, planetary science, and earth penetration mechanics, are just a few of the application areas. Although the mechanical behavior of granular materials of various types have been studied extensively for several decades, the dynamic behavior of such materials remains poorly understood. High-quality experimental data are needed to improve our general understanding of granular material compaction physics. This study will describe how an instrumented plunger impact system can be used to measure pressure-density relationships for model materials at high and controlled strain rates and subsequentlymore » used for computational modeling.« less

  7. Theoretical study of EAS hadronic structure

    NASA Technical Reports Server (NTRS)

    Popova, L.

    1985-01-01

    The structure of extensive air showers (EAS) is determined mainly by the energetic hadrons. They are strongly collimated in the core of the shower and essential difficulties are encountered for resolution of individual hadrons. The properties for resolution are different from the variety of hadron detectors used in EAS experiments. This is the main difficulty in obtaining a general agreement between actually registered data with different detectors. The most plausible source for disagreement is the uncertainty in determination of the energy of individual hadrons. This research demonstrates that a better agreement can be obtained with the average tendency of hadronic measurements if one assumes a larger coefficient of inelasticity and stronger energy increase of the total inelastic cross section in high energy pion interactions. EAS data above 10 to the 5th power GeV are revealing a faster development of hadronic cascades in the air then can be expected by extrapolating the parameters of hadron interactions obtained in accelerator measurements.

  8. Energy Conservation for Granular Coal Injection into a Blast Furnace

    NASA Astrophysics Data System (ADS)

    Guo, Hongwei; Su, Buxin; Zhang, Jianliang; Shao, Jiugang; Zuo, Haibin; Ren, Shan

    2012-08-01

    Due to the lack of knowledge regarding the combustion of granular coal injected into a blast furnace, injection characteristics of granular coal were first studied through proximate analysis, element analysis, and research of explosivity, ignition point, meltability of ash, grindability, calorific value, etc. Using a sampling device in the raceway combined with petrographic analysis, during the combustion process of granular coal with high crystal water and volatile in raceway, cracks and bursts were found, leading to a reduction of particle size. Based on a model of mass control and dynamic theory of particle combustion, the transition dynamic model for cracking in combustion of granular coal was found, and the critical value of cracking ratio (ΩP) for granular coal combustion in the raceway was calculated. Finally, the utilization ratio and energy efficiency of granular coal used in the blast furnace were discussed, offering theoretical foundation and technical support for intensifying granular coal combustion and promoting granular coal injection.

  9. Future Electron-Hadron Colliders

    SciTech Connect

    Litvinenko, V.

    2010-05-23

    Outstanding research potential of electron-hadron colliders (EHC) was clearly demonstrated by first - and the only - electron-proton collider HERA (DESY, Germany). Physics data from HERA revealed new previously unknown facets of Quantum Chromo-Dynamics (QCD). EHC is an ultimate microscope probing QCD in its natural environment, i.e. inside the hadrons. In contrast with hadrons, electrons are elementary particles with known initial state. Hence, scattering electrons from hadrons provides a clearest pass to their secrets. It turns EHC into an ultimate machine for high precision QCD studies and opens access to rich physics with a great discovery potential: solving proton spin puzzle, observing gluon saturation or physics beyond standard model. Access to this physics requires high-energy high-luminosity EHCs and a wide reach in the center-of-mass (CM) energies. This paper gives a brief overview of four proposed electron-hadron colliders: ENC at GSI (Darmstadt, Germany), ELIC/MEIC at TJNAF (Newport News, VA, USA), eRHIC at BNL (Upton, NY, USA) and LHeC at CERN (Geneva, Switzerland). Future electron-hadron colliders promise to deliver very rich physics not only in the quantity but also in the precision. They are aiming at very high luminosity two-to-four orders of magnitude beyond the luminosity demonstrated by the very successful HERA. While ENC and LHeC are on opposite side of the energy spectrum, eRHIC and ELIC are competing for becoming an electron-ion collider (EIC) in the U.S. Administrations of BNL and Jlab, in concert with US DoE office of Nuclear Physics, work on the strategy for down-selecting between eRHIC and ELIC. The ENC, EIC and LHeC QCD physics programs to a large degree are complimentary to each other and to the LHC physics. In last decade, an Electron Ion Collider (EIC) collaboration held about 25 collaboration meetings to develop physics program for EIC with CM energy {approx}100 GeV. One of these meetings was held at GSI, where ENC topic was in the

  10. Axisymmetric collapses of granular columns

    NASA Astrophysics Data System (ADS)

    Lube, Gert; Huppert, Herbert E.; Sparks, R. Stephen J.; Hallworth, Mark A.

    2004-06-01

    Experimental observations of the collapse of initially vertical columns of small grains are presented. The experiments were performed mainly with dry grains of salt or sand, with some additional experiments using couscous, sugar or rice. Some of the experimental flows were analysed using high-speed video. There are three different flow regimes, dependent on the value of the aspect ratio a {=} h_i/r_i, where h_i and r_i are the initial height and radius of the granular column respectively. The differing forms of flow behaviour are described for each regime. In all cases a central, conically sided region of angle approximately 59(°) , corresponding to an aspect ratio of 1.7, remains undisturbed throughout the motion. The main experimental results for the final extent of the deposit and the time for emplacement are systematically collapsed in a quantitative way independent of any friction coefficients. Along with the kinematic data for the rate of spread of the front of the collapsing column, this is interpreted as indicating that frictional effects between individual grains in the bulk of the moving flow only play a role in the last instant of the flow, as it comes to an abrupt halt. For a {<} 1.7, the measured final runout radius, r_infty, is related to the initial radius by r_infty {=} r_i(1 {+} 1.24a); while for 1.7 {<} a the corresponding relationship is r_infty {=} r_i(1 {+} 1.6a(1/2) ). The time, t_infty, taken for the grains to reach r_infty is given by t_infty {=} 3(h_i/g)(1/2} {=} 3(r_i/g)({1/2}a^{1/2)) , where g is the gravitational acceleration. The insights and conclusions gained from these experiments can be applied to a wide range of industrial and natural flows of concentrated particles. For example, the observation of the rapid deposition of the grains can help explain details of the emplacement of pyroclastic flows resulting from the explosive eruption of volcanoes.

  11. Characterizing the rheology of fluidized granular matter.

    PubMed

    Desmond, Kenneth W; Villa, Umberto; Newey, Mike; Losert, Wolfgang

    2013-09-01

    In this study we characterize the rheology of fluidized granular matter subject to secondary forcing. Our approach consists of first fluidizing granular matter in a drum half filled with grains via simple rotation and then superimposing oscillatory shear perpendicular to the downhill flow direction. The response of the system is mostly linear, with a phase lag between the grain motion and the oscillatory forcing. The rheology of the system can be well characterized by the GDR MiDi model if the system is forced with slow oscillations. The model breaks down when the forcing time scale becomes comparable to the characteristic time for energy dissipation in the flow. PMID:24125256

  12. Cluster Instability in Freely Evolving Granular Gases

    NASA Astrophysics Data System (ADS)

    Brey, J. Javier

    A granular medium is formed by a large number of macroscopic particles or grains. Here large must be understood at a macroscopic level, i.e. a few thousands or even a few hundreds is already a large number in the present context, as compared with molecular systems which contain a number of atoms or molecules of the order of the Avogadro number. In this lecture, we will restrict ourselves to dry granular systems in which there is not any other fluid around the grains. Also, electrical effects are not considered. Under these circumstances, the grain-grain interaction can be taken as purely repulsive with no attractive part.

  13. Challenges in Predicting Planetary Granular Mechanics

    NASA Technical Reports Server (NTRS)

    Metzger, Philip T.

    2005-01-01

    Through the course of human history, our needs in agriculture, habitat construction, and resource extraction have driven us to gain more experience working with the granular materials of planet Earth than with any other type of substance in nature, with the possible exception being water. Furthermore, throughout the past two centuries we have seen a dramatic and ever growing interest among scientists and engineers to understand and predict both its static and rheological properties. Ironically, however, despite this wealth of experience we still do not have a fundamental understanding of the complex physical phenomena that emerge even as just ordinary sand is shaken, squeezed or poured. As humanity is now reaching outward through the solar system, not only robotic ally but also with our immediate human presence, the need to understand and predict granular mechanics has taken on a new dimension. We must learn to farm, build and mine the regoliths of other planets where the environmental conditions are different than on Earth, and we are rapidly discovering that the effects of these environmental conditions are not trivial. Some of the relevant environmental features include the regolith formation processes throughout a planet's geologic and hydrologic history, the unknown mixtures of volatiles residing within the soil, the relative strength of gravitation, d the atm9spheric pressure and its seasonal variations. The need to work with soils outside our terrestrial experience base provides us with both a challenge and an opportunity. The challenge is to learn how to extrapolate our experience into these new planetary conditions, enabling the engineering decisions that are needed right now as we take the next few steps in solar system exploration. The opportunity is to use these new planetary environments as laboratories that will help us to see granular mechanics in new ways, to challenge our assumptions, and to help us finally unravel the elusive physics that lie

  14. How granularity issues concern biomedical ontology integration.

    PubMed

    Schulz, Stefan; Boeker, Martin; Stenzhorn, Holger

    2008-01-01

    The application of upper ontologies has been repeatedly advocated for supporting interoperability between domain ontologies in order to facilitate shared data use both within and across disciplines. We have developed BioTop as a top-domain ontology to integrate more specialized ontologies in the biomolecular and biomedical domain. In this paper, we report on concrete integration problems of this ontology with the domain-independent Basic Formal Ontology (BFO) concerning the issue of fiat and aggregated objects in the context of different granularity levels. We conclude that the third BFO level must be ignored in order not to obviate cross-granularity integration. PMID:18487840

  15. The PHENIX Hadron Blind Detector

    SciTech Connect

    Durham, J. M.

    2009-03-10

    Dielectron measurements by the PHENIX Experiment at RHIC are limited by the combinatorial background from electrons and positrons which are not produced in the same pair. The Hadron Blind Detector will allow a substantial reduction of this background by correctly identifying dielectrons from photon conversions and pion Dalitz decays which dominate the signal in the low mass region of the spectrum. Triple GEM stacks, with a CsI photocathode deposited on the uppermost GEM, detect Cherenkov light produced by electrons in a CF{sub 4} radiator. The transparency of CF{sub 4}, high quantum efficiency of CsI in the UV, and absence of a window between the gas radiator and the GEMs allow a large photoelectron yield, while minimizing the hadron signal. Results from the HBD in RHIC's Run-7 and preparations for upcoming runs are discussed.

  16. Hadron therapy information sharing prototype

    PubMed Central

    Roman, Faustin Laurentiu; Abler, Daniel; Kanellopoulos, Vassiliki; Amoros, Gabriel; Davies, Jim; Dosanjh, Manjit; Jena, Raj; Kirkby, Norman; Peach, Ken; Salt, Jose

    2013-01-01

    The European PARTNER project developed a prototypical system for sharing hadron therapy data. This system allows doctors and patients to record and report treatment-related events during and after hadron therapy. It presents doctors and statisticians with an integrated view of adverse events across institutions, using open-source components for data federation, semantics, and analysis. There is a particular emphasis upon semantic consistency, achieved through intelligent, annotated form designs. The system as presented is ready for use in a clinical setting, and amenable to further customization. The essential contribution of the work reported here lies in the novel data integration and reporting methods, as well as the approach to software sustainability achieved through the use of community-supported open-source components. PMID:23824127

  17. Lifetime measurements for bottom hadrons

    SciTech Connect

    Wolf, G.

    1984-09-01

    The review of lifetime measurements of bottom hadrons begins with a first measurement by JADE, followed by similar measurements by MAC and MKII groups. New MAC data are reviewed based on a total of 75,000 multihadron events taken at a c.m. energy of 29 GeV. According to Monte Carlo calculations, 18% of the lepton candidates stem from charm decay and roughly 30% were misidentified hadrons. DELCO studied electrons obtained from 42,000 multihadron events at 29 GeV. The electrons were identified by means of Cerenkov counters. JADE analayzed 22,000 multihadron events at 35 GeV. Data were analyzed using two methods - one using a sample of b-enriched events, and the other using weighted distributions. The TASSO results were obtained with two different configurations of the detector - one of which used a drift chamber and the other a vertex detector. (LEW)

  18. Hadronic resonances enhanced by thresholds

    NASA Astrophysics Data System (ADS)

    Caramés, T. F.; Valcarce, A.

    2016-07-01

    We present a neat example of a meson-baryon system where the vicinity of two different thresholds enhances the binding of a hadronic resonance, a pentaquark. As a consequence the pattern of states may change when moving among different flavor sectors, what poses a warning on naive extrapolations to heavy flavor sectors based on systematic expansions. For this purpose we simultaneously analyze the N D bar and NB two-hadron systems looking for possible bound states or resonances. When a resonance is controlled by a coupled-channel effect, going to a different flavor sector may enhance or diminish the binding. This effect may, for example, generate significant differences between the charmonium and bottomonium spectra above open-flavor thresholds or pentaquark states in the open-charm and open-bottom sectors.

  19. Modeling QCD for Hadron Physics

    NASA Astrophysics Data System (ADS)

    Tandy, P. C.

    2011-10-01

    We review the approach to modeling soft hadron physics observables based on the Dyson-Schwinger equations of QCD. The focus is on light quark mesons and in particular the pseudoscalar and vector ground states, their decays and electromagnetic couplings. We detail the wide variety of observables that can be correlated by a ladder-rainbow kernel with one infrared parameter fixed to the chiral quark condensate. A recently proposed novel perspective in which the quark condensate is contained within hadrons and not the vacuum is mentioned. The valence quark parton distributions, in the pion and kaon, as measured in the Drell Yan process, are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter equations.

  20. Modeling QCD for Hadron Physics

    SciTech Connect

    Tandy, P. C.

    2011-10-24

    We review the approach to modeling soft hadron physics observables based on the Dyson-Schwinger equations of QCD. The focus is on light quark mesons and in particular the pseudoscalar and vector ground states, their decays and electromagnetic couplings. We detail the wide variety of observables that can be correlated by a ladder-rainbow kernel with one infrared parameter fixed to the chiral quark condensate. A recently proposed novel perspective in which the quark condensate is contained within hadrons and not the vacuum is mentioned. The valence quark parton distributions, in the pion and kaon, as measured in the Drell Yan process, are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter equations.

  1. Hard processes in hadronic interactions

    SciTech Connect

    Satz, H. |; Wang, X.N.

    1995-07-01

    Quantum chromodynamics is today accepted as the fundamental theory of strong interactions, even though most hadronic collisions lead to final states for which quantitative QCD predictions are still lacking. It therefore seems worthwhile to take stock of where we stand today and to what extent the presently available data on hard processes in hadronic collisions can be accounted for in terms of QCD. This is one reason for this work. The second reason - and in fact its original trigger - is the search for the quark-gluon plasma in high energy nuclear collisions. The hard processes to be considered here are the production of prompt photons, Drell-Yan dileptons, open charm, quarkonium states, and hard jets. For each of these, we discuss the present theoretical understanding, compare the resulting predictions to available data, and then show what behaviour it leads to at RHIC and LHC energies. All of these processes have the structure mentioned above: they contain a hard partonic interaction, calculable perturbatively, but also the non-perturbative parton distribution within a hadron. These parton distributions, however, can be studied theoretically in terms of counting rule arguments, and they can be checked independently by measurements of the parton structure functions in deep inelastic lepton-hadron scattering. The present volume is the work of Hard Probe Collaboration, a group of theorists who are interested in the problem and were willing to dedicate a considerable amount of their time and work on it. The necessary preparation, planning and coordination of the project were carried out in two workshops of two weeks` duration each, in February 1994 at CERn in Geneva andin July 1994 at LBL in Berkeley.

  2. Hadronic Resonances from Lattice QCD

    SciTech Connect

    Lichtl, Adam C.; Bulava, John; Morningstar, Colin; Edwards, Robert; Mathur, Nilmani; Richards, David; Fleming, George; Juge, K. Jimmy; Wallace, Stephen J.

    2007-10-26

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  3. Hadron Properties with FLIC Fermions

    SciTech Connect

    James Zanotti; Wolodymyr Melnitchouk; Anthony Williams; J Zhang

    2003-07-01

    The Fat-Link Irrelevant Clover (FLIC) fermion action provides a new form of nonperturbative O(a)-improvement in lattice fermion actions offering near continuum results at finite lattice spacing. It provides computationally inexpensive access to the light quark mass regime of QCD where chiral nonanalytic behavior associated with Goldstone bosons is revealed. The motivation and formulation of FLIC fermions, its excellent scaling properties and its low-lying hadron mass phenomenology are presented.

  4. Physics with low energy hadrons

    SciTech Connect

    Guttierez, G.; Littenberg, L.

    1997-10-01

    The prospects for low energy hadron physics at the front end of a muon collider (FMC) are discussed. The FMC, as conceived for the purposes of this workshop, is pretty close to a classical idea of a koan factory. There is an order of magnitude advantage of the FMC front end over the AGS for K{sup {minus}} and {anti p} production below 5 GeV/c.

  5. Hadronic Resonances from Lattice QCD

    SciTech Connect

    John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace

    2007-06-16

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  6. Cross sections at hadron colliders

    SciTech Connect

    Paige, F.E.

    1982-01-01

    The predicted cross sections are given for new Z'/sup 0/ bosons, for the Drell-Yan continuum of ..mu../sup +/..mu../sup -/ pairs, for high p/sub T/ hadron jets, for high p/sub T/ single photons, and for the associated production of heavy quarks. These processes have been selected not to cover the most interesting physics, but to provide a representative selection of cross sections for which to compare various energies and luminosities.

  7. Cosmic rays and hadronic interactions

    NASA Astrophysics Data System (ADS)

    Lipari, Paolo

    2015-08-01

    The study of cosmic rays, and more in general of the "high energy universe" is at the moment a vibrant field that, thanks to the observations by several innovative detectors for relativistic charged particles, gamma-rays, and neutrinos continue to generate surprising and exciting results. The progress in the field is rapid but many fundamental problems remain open. There is an intimate relation between the study of the high energy universe and the study of the properties of hadronic interactions. High energy cosmic rays can only be studied detecting the showers they generate in the atmosphere, and for the interpretation of the data one needs an accurate modeling of the collisions between hadrons. Also the study of cosmic rays inside their sources and in the Galaxy requires a precise description of hadronic interactions. A program of experimental studies at the LHC and at lower energy, designed to address the most pressing problems, could significantly reduce the existing uncertainties and is very desirable. Such an experimental program would also have a strong intrinsic scientific interest, allowing the broadening and deepening of our understanding of Quantum Chromo Dynamics in the non-perturbative regime, the least understood sector of the Standard Model of particle physics. It should also be noted that the cosmic ray spectrum extends to particles with energy E ˜ 1020 eV, or a nucleon-nucleon c.m. energy √s ≃ 430 TeV, 30 times higher than the current LHC energy. Cosmic ray experiments therefore offer the possibility to perform studies on the properties of hadronic interactions that are impossible at accelerators.

  8. Theory of hadronic nonperturbative models

    SciTech Connect

    Coester, F.; Polyzou, W.N.

    1995-08-01

    As more data probing hadron structure become available hadron models based on nonperturbative relativistic dynamics will be increasingly important for their interpretation. Relativistic Hamiltonian dynamics of few-body systems (constituent-quark models) and many-body systems (parton models) provides a precisely defined approach and a useful phenomenology. However such models lack a quantitative foundation in quantum field theory. The specification of a quantum field theory by a Euclidean action provides a basis for the construction of nonperturbative models designed to maintain essential features of the field theory. For finite systems it is possible to satisfy axioms which guarantee the existence of a Hilbert space with a unitary representation of the Poincare group and the spectral condition which ensures that the spectrum of the four-momentum operator is in the forward light cone. The separate axiom which guarantees locality of the field operators can be weakened for the construction for few-body models. In this context we are investigating algebraic and analytic properties of model Schwinger functions. This approach promises insight into the relations between hadronic models based on relativistic Hamiltonian dynamics on one hand and Bethe-Salpeter Green`s-function equations on the other.

  9. Three Lectures on Hadron Physics

    NASA Astrophysics Data System (ADS)

    Roberts, Craig D.

    2016-04-01

    These lectures explain that comparisons between experiment and theory can expose the impact of running couplings and masses on hadron observables and thereby aid materially in charting the momentum dependence of the interaction that underlies strong-interaction dynamics. The series begins with a primer on continuum QCD, which introduces some of the basic ideas necessary in order to understand the use of Schwinger functions as a nonperturbative tool in hadron physics. It continues with a discussion of confinement and dynamical symmetry breaking (DCSB) in the Standard Model, and the impact of these phenomena on our understanding of condensates, the parton structure of hadrons, and the pion electromagnetic form factor. The final lecture treats the problem of grand unification; namely, the contemporary use of Schwinger functions as a symmetry-preserving tool for the unified explanation and prediction of the properties of both mesons and baryons. It reveals that DCSB drives the formation of diquark clusters in baryons and sketches a picture of baryons as bound-states with Borromean character. Planned experiments are capable of validating the perspectives outlined in these lectures.

  10. Hadron Production Measurements at CERN

    NASA Astrophysics Data System (ADS)

    Catanesi, M. G.

    2007-03-01

    Hadron production measurements for neutrino experiments is a well established field at CERN since the '70s. Precise prediction of atmospheric neutrino fluxes, characterization of accelerator neutrino beams, quantification of pion production and capture for neutrino factory designs, all of these would profit from hadron production measurements. In recent years, interest in such studies was revived and new generation of low-energy (from 3 to 400 GeV) hadron production experiments were built or proposed. Such experiments all share a basic design, consisting in the presence of open-geometry spectrometers, as close as possible to full angular coverage, and aiming at full particle identification. New results are now provided by Harp in the very low energy range (3 to 15 GeV/c) and by NA49 at 158 GeV/c. In the next years NA49- future will explore the medium energy range (30 to 400 GeV/c) and at LHC energies for the first time thanks to the TOTEM experiment, it will be possible to measure with unprecedented precision the total cross section beyond 1 TeV/c.

  11. Performance of Anammox granular sludge bed reactor started up with nitrifying granular sludge.

    PubMed

    Zheng, Ping; Lin, Feng-mei; Hu, Bao-lan; Chen, Jian-song

    2004-01-01

    The anaerobic ammonia oxidation (Anammox) granular sludge bed reactor was started up successfully with nitrifying granular sludge. During the operation, the nitrifying granular sludge was gradually converted into Anammox granular sludge with good settling property and high conversion activity. The Anammox reactor worked well with the shortest HRT of 2.43 h. Under the condition that HRT was 6.39 h and influent concentration of ammonia and nitrite was 10 mmol/L, the removal of ammonia and nitrite was 97.17% and 100.00%, respectively. Corresponding volumetric total nitrogen loading rate and volumetric total nitrogen conversion rate were 100.83 mmol/(L x d) and 98.95 mmol/(L x d). The performance of Anammox reactor was efficient and stable. PMID:15137666

  12. Granular Elasticity’ and the loss of elastic stability in granular materials

    SciTech Connect

    P. W. Humrickhouse

    2009-07-01

    A recently proposed hyperelastic model for granular materials, called "granular elasticity", identifies a yield angle as a result of thermodynamic instability. GE gives yield angles that are smaller than those found in real materials; a generalization of the theory is considered here that includes dependence on the third strain invariant. This generalization proves unsuccessful, as it gives smaller, not larger, yield angles. Fully convex hyperelastic models are identified as a point for future investigation.

  13. DOWNFLOW GRANULAR FILTRATION OF ACTIVATED SLUDGE EFFLUENTS

    EPA Science Inventory

    The performance of downflow granular filters subjected to effluents from activated sludge processes was investigated at the EPA-DC Pilot Plant in Washington, D.C. Several media combinations were investigated, including both single anthracite and dual anthracite-sand configuration...

  14. Granular Gas in a Periodic Lattice

    ERIC Educational Resources Information Center

    Dorbolo, S.; Brandenbourger, M.; Damanet, F.; Dister, H.; Ludewig, F.; Terwagne, D.; Lumay, G.; Vandewalle, N.

    2011-01-01

    Glass beads are placed in the compartments of a horizontal square grid. This grid is then vertically shaken. According to the reduced acceleration [image omitted] of the system, the granular material exhibits various behaviours. By counting the number of beads in each compartment after shaking, it is possible to define three regimes. At low…

  15. Multi-scale modelling of granular avalanches

    NASA Astrophysics Data System (ADS)

    Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves

    2013-06-01

    Avalanches, debris flows, and landslides are geophysical hazards, which involve rapid mass movement of granular solids, water and air as a single-phase system. The dynamics of a granular flow involve at least three distinct scales: the micro-scale, meso-scale, and the macro-scale. This study aims to understand the ability of continuum models to capture the micro-mechanics of dry granular collapse. Material Point Method (MPM), a hybrid Lagrangian and Eulerian approach, with Mohr-Coulomb failure criterion is used to describe the continuum behaviour of granular column collapse, while the micromechanics is captured using Discrete Element Method (DEM) with tangential contact force model. The run-out profile predicted by the continuum simulations matches with DEM simulations for columns with small aspect ratios (`h/r' < 2), however MPM predicts larger run-out distances for columns with higher aspect ratios (`h/r' > 2). Energy evolution studies in DEM simulations reveal higher collisional dissipation in the initial free-fall regime for tall columns. The lack of a collisional energy dissipation mechanism in MPM simulations results in larger run-out distances. Micro-structural effects, such as shear band formations, were observed both in DEM and MPM simulations. A sliding flow regime is observed above the distinct passive zone at the core of the column. Velocity profiles obtained from both the scales are compared to understand the reason for a slow flow run-out mobilization in MPM simulations.

  16. Complex flows in granular and quantum systems

    NASA Astrophysics Data System (ADS)

    Herrera, Mark Richard

    In this thesis we investigate three problems involving complex flows in granular and quantum systems. (a) We first study the dynamics of granular particles in a split-bottom shear cell experiment. We utilize network theory to quantify the dynamics of the granular system at the mesoscopic scale. We find an apparent phase transition in the formation of a giant component of broken links as a function of applied shear. These results are compared to a numerical model where breakages are based on the amount of local stretching in the granular pile. (b) Moving to quantum mechanical systems, we study revival and echo phenomena in systems of anharmonically confined atoms, and find a novel phenomena we call the "pre-revival echo". We study the effect of size and symmetry of the perturbations on the various echoes and revivals, and form a perturbative model to describe the phenomena. We then model the effect of interactions using the Gross-Pitaevskii Equation and study interactions' effect on the revivals. (c) Lastly, we continue to study the effect of interactions on particles in weakly anharmonic traps. We numerically observe a "dynamical localization" phenomena in the presence of both anharmonicity and interactions. States may remain localized or become spread out in the potential depending on the strength and sign of the anharmonicity and interactions. We formulate a model for this phenomena in terms of a classical phase space.

  17. Granular materials interacting with thin flexible rods

    NASA Astrophysics Data System (ADS)

    Neto, Alfredo Gay; Campello, Eduardo M. B.

    2016-01-01

    In this work, we develop a computational model for the simulation of problems wherein granular materials interact with thin flexible rods. We treat granular materials as a collection of spherical particles following a discrete element method (DEM) approach, while flexible rods are described by a large deformation finite element (FEM) rod formulation. Grain-to-grain, grain-to-rod, and rod-to-rod contacts are fully permitted and resolved. A simple and efficient strategy is proposed for coupling the motion of the two types (discrete and continuum) of materials within an iterative time-stepping solution scheme. Implementation details are shown and discussed. Validity and applicability of the model are assessed by means of a few numerical examples. We believe that robust, efficiently coupled DEM-FEM schemes can be a useful tool to the simulation of problems wherein granular materials interact with thin flexible rods, such as (but not limited to) bombardment of grains on beam structures, flow of granular materials over surfaces covered by threads of hair in many biological processes, flow of grains through filters and strainers in various industrial segregation processes, and many others.

  18. Bipotential continuum models for granular mechanics

    NASA Astrophysics Data System (ADS)

    Goddard, Joe

    2014-03-01

    Most currently popular continuum models for granular media are special cases of a generalized Maxwell fluid model, which describes the evolution of stress and internal variables such as granular particle fraction and fabric,in terms of imposed strain rate. It is shown how such models can be obtained from two scalar potentials, a standard elastic free energy and a ``dissipation potential'' given rigorously by the mathematical theory of Edelen. This allows for a relatively easy derivation of properly invariant continuum models for granular media and fluid-particle suspensions within a thermodynamically consistent framework. The resulting continuum models encompass all the prominent regimes of granular flow, ranging from the quasi-static to rapidly sheared, and are readily extended to include higher-gradient or Cosserat effects. Models involving stress diffusion, such as that proposed recently by Kamrin and Koval (PRL 108 178301), provide an alternative approach that is mentioned in passing. This paper provides a brief overview of a forthcoming review articles by the speaker (The Princeton Companion to Applied Mathematics, and Appl. Mech. Rev.,in the press, 2013).

  19. Granular dynamics under shear with deformable boundaries

    NASA Astrophysics Data System (ADS)

    Geller, Drew; Backhaus, Scott; Ecke, Robert

    2015-03-01

    Granular materials under shear develop complex patterns of stress as the result of granular positional rearrangements under an applied load. We consider the simple planar shear of a quasi two-dimensional granular material consisting of bi-dispersed nylon cylinders confined between deformable boundaries. The aspect ratio of the gap width to total system length is 50, and the ratio of particle diameter to gap width is about 10. This system, designed to model a long earthquake fault with long range elastic coupling through the plates, is an interesting model system for understanding effective granular friction because it essentially self tunes to the jamming condition owing to the hardness of the grains relative to that of the boundary material, a ratio of more than 1000 in elastic moduli. We measure the differential strain displacements of the plates, the inhomogeneous stress distribution in the plates, the positions and angular orientations of the individual grains, and the shear force, all as functions of the applied normal stress. There is significant stick-slip motion in this system that we quantify through our quantitative measurements of both the boundary and the grain motion, resulting in a good characterization of this sheared 2D hard sphere system.

  20. Drag on intruder in dense granular flows

    NASA Astrophysics Data System (ADS)

    Zheng, Hu; Bares, Jonathan; Wang, Dong; Behringer, Robert

    2015-11-01

    We perform an experimental study on an intruder dragged at a constant force in a quasi-statically cyclic-sheared granular medium. A Teflon disk is embedded in a layer of bidisperse photoelastic disks. The granular medium is contained in a horizontal square cell, which can be deformed into a parallelogram with the same area to produce simple shear. We find that the forward motion of the intruder happens at the fragile state during shear reversals, while only reversible affine motion could be found at the Jammed state. There is a burst of non-affine motion for the granular particles at each shear reversal. For a range of packing fractions, the cumulative intruder displacement shows a linear increase proportional to the number of cycles of shear. To explain the behavior of intruder motion, we analyze the coordination number, density, affine and non-affine motion of disk-granular system variations as the shear strain. We acknowledge support from NSF Grant No. DMR1206351, NASA Grant No. NNX15AD38G and the W.M. Keck Foundation.

  1. Urea phosphate as granular or fluid fertilizers

    SciTech Connect

    Blouin, G.M.

    1984-01-01

    Studies are being conducted of the production and agronomic characteristics of the phosphoric acid-urea adduct, urea phosphate, and of the various granular and fluid fertilizers that can be produced from it. Flowsheets are given for the production of urea phosphate. Characteristics of unpurified and purified urea phosphate are also given. (DLC)

  2. A numerical laboratory for granular solids

    SciTech Connect

    Trent, B.C.; Margolin, L.G.; Lawrence Livermore National Lab., CA )

    1989-01-01

    The behavior of cemented granular material is complex and difficult to characterize. Physical tests on laboratory-size specimens are time consuming and often inconclusive, due to the variable nature of the bulk material. As an alternate approach, we have used the distinct element method to construct numerical samples of cemented granular material. The model allows us to verify which are the important microphysical processes determining material behavior. We can do parameter studies, continuously varying the material properties of the bonding material and the topology of the bonds themselves, to see how the macroscopic properties depend upon the microscopic structure. We illustrate our program with two types of calculations. The first series consists of measuring the macroscopic p-wave and the s-wave speeds of the numerical sample, and using them to infer elastic properties of the bulk material. We also investigate how the number and size of the bonds influence bulk response. In the second series, we look at crack growth in granular materials. The Griffith theory of crack growth assumes an ideally flat crack. In granular materials and in our simulation, the crack is formed when many consecutive bonds in the material are broken.

  3. Testing ergodicity in dense granular systems

    NASA Astrophysics Data System (ADS)

    Gao, Guo-Jie; Blawzdziewicz, Jerzy; O'Hern, Corey

    2008-03-01

    The Edwards' entropy formalism provides a statistical mechanical framework for describing dense granular systems. Experiments on vibrated granular columns and numerical simulations of quasi- static shear flow of dense granular systems have provided indirect evidence that the Edwards' theory may accurately describe certain aspects of these systems. However, a fundamental assumption of the Edwards' description---that all mechanically stable (MS) granular packings at a given packing fraction and externally imposed stress are equally accessible---has not been explicitly tested. We investigate this assumption by generating all mechanically stable hard disk packings in small bidisperse systems using a protocol where we successively compress or decompress the system followed by energy minimization. We then apply quasi-static shear flow at zero pressure to these MS packings and record the MS packings that occur during the shear flow. We generate a complete library of the allowed MS packings at each value of shear strain and determine the frequency with which each MS packing occurs. We find that the MS packings do not occur with equal probability at any value of shear strain. In fact, in small systems we find that the evolution becomes periodic with a period that grows with system-size. Our studies show that ergodicity can be improved by either adding random fluctuations to the system or increasing the system size.

  4. EPA'S RESEARCH PROGRAM IN GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Research into Granular Activated Carbon (GAC) for use in drinking water treatment has a long history in the Drinking Water Research Division and its predecessor organizations. tudies were conducted by the U.S. Public Health Service in the late fifties and early sixties to examine...

  5. Motile Fluids: Granular, Colloidal and Living

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Sriram

    2014-03-01

    My talk will present our recent results from theory, simulation and experiment on flocking, swarming and instabilities in diverse realizations of active systems. The findings I will report include: flocking at a distance in vibrated granular monolayers; the active hydrodynamics of self-propelled solids; clusters, asters and oscillations in colloidal chemotaxis. Supported by a J C Bose Fellowship.

  6. Measuring the configurational temperature of granular media

    NASA Astrophysics Data System (ADS)

    Schröter, Matthias

    2009-03-01

    Twenty years ago Edwards and Oakeshott suggested developing a statistical mechanics of static granular media based on the idea that the logarithm of the number of mechanically stable states of a specific sample constitutes the relevant entropy [1]. From this entropy then, a configurational temperature, named compactivity, could be derived. However, in the absence of an appropriate thermometer to measure compactivity, the question if it is indeed a relevant state variable remained untested. Only recently it was shown that the steady state volume fluctuations of a periodically driven sample can be used to measure the compactivity of a granular sample including its dependence on volume fraction and surface friction of the particles [2]. This opens up the possibility of studying questions like the existence of a zeroth law of granular thermodynamics or the relationship between compactivity and other forms of granular temperature. [1] Edwards and Oakeshott, Physica A 157, 1080 (1989). [2] M. Schr"oter, D. Goldman, and H. L. Swinney Phys. Rev. E 71, 030301(R) (2005)

  7. Rheology of Dense Granular Mixtures and Slurries

    NASA Astrophysics Data System (ADS)

    Tewoldebrhan, Bereket Yohannes

    Dense granular flows, characterized by multiple contacts between grains, are common in many industrial processes and natural events, such as debris flows. Understanding the characteristics of these flows is crucial to predict quantities such as bedrock erosion and distance traveled by debris flows. However, the rheological properties of these flows are complicated due to wide particle size distribution and presence of interstitial fluids. Models for dense sheared granular materials indicate that their rheological properties depend on particle size, but the representative particle size for mixtures is not obvious. Using the discrete element method (DEM) we study sheared granular binary mixtures in a Couette cell to determine the relationship and rheological parameters such as stress and effective coefficient of friction and particle size distribution. The results indicate that the stress does not depend monotonically on the average particle size as it does in models derived from simple dimensional consideration. The stress has an additional dependence on a measure of the effective free volume per particle that is adapted from an expression for packing of monosized particles near the jammed state. The effective friction also has a complicated dependence on particle size distribution. For these systems of relatively hard particles, these relationships are governed largely by the ratio between average collision times and mean-free-path times. The characteristics of shallow free surface flows, important for applications such as debris flows, are different from confined systems. To address this, we also study shallow granular flows in a rotating drum. The stress at the boundary, height profiles and segregation patterns from DEM simulations are quantitatively similar to the results obtained from physical experiments of shallow granular flows in rotating drums. Individual particle-bed impacts rather than enduring contacts dominate the largest forces on the drum bed, which

  8. Granular Mechanics in the Asteroid Regime

    NASA Astrophysics Data System (ADS)

    Sanchez, Paul; Swift, M. R.; Scheeres, D. J.

    2009-09-01

    We study the granular mechanics properties of asteroid regolith and of asteroids modeled as gravitational aggregates using soft-sphere molecular simulation codes. For definiteness we assume parameters similar to the asteroid Itokawa, for which we have detailed observational data. Essential questions that can be studied using the techniques of granular mechanics are why large blocks dominate 80% of the surface of Itokawa and why the remaining 20% is uniformly covered with smaller particles, indicating global segregation mechanisms at work on this body. The prime energy source proposed for the segregation of granular materials on asteroids has been seismic shaking due to hypervelocity impacts with asteroids much smaller than the target body. We analyze the detailed mechanics of segregation physics in the asteroid environment due to such interactions. First we analyze the so-called Brazil Nut Effect (BNE), which preferentially causes larger particles to rise to the highest potential energy in a granular material. We note that the regions of highest potential on Itokawa are dominated by larger blocks, while the potential lows are dominated by smaller blocks. We verify and characterise the BNE effect in an asteroid environment under a variety of boundary and shaking conditions. We also extend our analyses to a global-scale simulation of aggregates, modeling the response of self-gravitating granules of a mixture of sizes to impacts. Analysis of such global-scale systems show additional mechanics that may account for the exposure of large blocks on the surface. Specifically we find that hypervelocity impacts are more effective in removing and transporting smaller regolith, exposing sub-surface larger blocks that might otherwise be covered in finer grained material. We discuss the scaling of granular mechanics effects from local regolith to global aggregate scale.

  9. Supporting user-defined granularities in a spatiotemporal conceptual model

    USGS Publications Warehouse

    Khatri, V.; Ram, S.; Snodgrass, R.T.; O'Brien, G. M.

    2002-01-01

    Granularities are integral to spatial and temporal data. A large number of applications require storage of facts along with their temporal and spatial context, which needs to be expressed in terms of appropriate granularities. For many real-world applications, a single granularity in the database is insufficient. In order to support any type of spatial or temporal reasoning, the semantics related to granularities needs to be embedded in the database. Specifying granularities related to facts is an important part of conceptual database design because under-specifying the granularity can restrict an application, affect the relative ordering of events and impact the topological relationships. Closely related to granularities is indeterminacy, i.e., an occurrence time or location associated with a fact that is not known exactly. In this paper, we present an ontology for spatial granularities that is a natural analog of temporal granularities. We propose an upward-compatible, annotation-based spatiotemporal conceptual model that can comprehensively capture the semantics related to spatial and temporal granularities, and indeterminacy without requiring new spatiotemporal constructs. We specify the formal semantics of this spatiotemporal conceptual model via translation to a conventional conceptual model. To underscore the practical focus of our approach, we describe an on-going case study. We apply our approach to a hydrogeologic application at the United States Geologic Survey and demonstrate that our proposed granularity-based spatiotemporal conceptual model is straightforward to use and is comprehensive.

  10. Unsolved problems in hadronic charm decay

    SciTech Connect

    Browder, T.E.

    1989-08-01

    This paper describes several outstanding problems in the study of hadronic decays of charmed mesons where further experimental work and theoretical understanding is needed. Four topics are stressed: double Cabibbo suppressed decays (DCSD) of D/sup +/ mesons, hadronic D/sub s/ decays, weak hadronic quasi-two-body decays to pairs of vector mesons, and penguin decays of D mesons. 24 refs., 10 figs., 5 tabs.

  11. Hadron Physics with PANDA at FAIR

    SciTech Connect

    Wiedner, Ulrich

    2011-10-21

    The recently established FAIR facility in Darmstadt has a broad program in the field of hadron and nuclear physics utilizing ion beams with unprecedented intensity and accuracy. The PANDA experiment, which is integrated in the HESR storage ring for antiprotons is at the center of the hadron physics program. It includes among others topics like hadron spectroscopy in the charmonium mass region and below, hyperon physics and electromagnetic processes.

  12. Heavy flavor production from photons and hadrons

    SciTech Connect

    Heusch, C.A.

    1982-01-01

    The present state of the production and observation of hadrons containing heavy quarks or antiquarks as valence constituents, in reactions initiated by real and (space-like) virtual photon or by hadron beams is discussed. Heavy flavor production in e/sup +/e/sup -/ annihilation, which is well covered in a number of recent review papers is not discussed, and similarly, neutrino production is omitted due to the different (flavor-changing) mechanisms that are involved in those reactions. Heavy flavors from spacelike photons, heavy flavors from real photons, and heavy flavors from hadron-hadron collisions are discussed. (WHK)

  13. Hadronization measurements in cold nuclear matter

    SciTech Connect

    Dupre, Raphael

    2015-05-01

    Hadronization is the non-perturbative process of QCD by which partons become hadrons. It has been studied at high energies through various processes, we focus here on the experiments of lepto-production of hadrons in cold nuclear matter. By studying the dependence of observables to the atomic number of the target, these experimentscan give information on the dynamic of the hadronization at the femtometer scale. In particular, we will present preliminary results from JLab Hall B (CLAS collaboration), which give unprecedented statistical precision. Then, we will present results of a phenomenological study showing how HERMES data can be described with pure energyloss models.

  14. Constitutive relations for steady, dense granular flows

    NASA Astrophysics Data System (ADS)

    Vescovi, D.; Berzi, D.; di Prisco, C. G.

    2011-12-01

    In the recent past, the flow of dense granular materials has been the subject of many scientific works; this is due to the large number of natural phenomena involving solid particles flowing at high concentration (e.g., debris flows and landslides). In contrast with the flow of dilute granular media, where the energy is essentially dissipated in binary collisions, the flow of dense granular materials is characterized by multiple, long-lasting and frictional contacts among the particles. The work focuses on the mechanical response of dry granular materials under steady, simple shear conditions. In particular, the goal is to obtain a complete rheology able to describe the material behavior within the entire range of concentrations for which the flow can be considered dense. The total stress is assumed to be the linear sum of a frictional and a kinetic component. The frictional and the kinetic contribution are modeled in the context of the critical state theory [8, 10] and the kinetic theory of dense granular gases [1, 3, 7], respectively. In the critical state theory, the granular material approaches a certain attractor state, independent on the initial arrangement, characterized by the capability of developing unlimited shear strains without any change in the concentration. Given that a disordered granular packing exists only for a range of concentration between the random loose and close packing [11], a form for the concentration dependence of the frictional normal stress that makes the latter vanish at the random loose packing is defined. In the kinetic theory, the particles are assumed to interact through instantaneous, binary and uncorrelated collisions. A new state variable of the problem is introduced, the granular temperature, which accounts for the velocity fluctuations. The model has been extended to account for the decrease in the energy dissipation due to the existence of correlated motion among the particles [5, 6] and to deal with non

  15. LHC: The Large Hadron Collider

    SciTech Connect

    Lincoln, Don

    2015-03-04

    The Large Hadron Collider (or LHC) is the world’s most powerful particle accelerator. In 2012, scientists used data taken by it to discover the Higgs boson, before pausing operations for upgrades and improvements. In the spring of 2015, the LHC will return to operations with 163% the energy it had before and with three times as many collisions per second. It’s essentially a new and improved version of itself. In this video, Fermilab’s Dr. Don Lincoln explains both some of the absolutely amazing scientific and engineering properties of this modern scientific wonder.

  16. Hadronic Structure from Perturbative Dressing

    NASA Astrophysics Data System (ADS)

    Arash, Firooz

    2005-09-01

    Perturbative dressing of a valence quark in QCD produces the internal structure of an extended object, the so-called Valon. The valon structure is universal and independent of the hosting hadron. Polarized and unpolarized proton and pion structure functions are calculated in the valon representation. One finds that although all the available data on g1p,n,d are easily reproduced, a sizable orbital angular momentum associated with the partonic structure of the valon is required in order to have a spin 1/2 valon.

  17. Charmed hadron photoproduction at COMPASS

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Yun; Guskov, Alexey

    2016-06-01

    Photoproduction of the charmonium-like state Zc(4200) and the charmed baryon Λ_c^* (2940) is investigated with an effective Lagrangian approach and the Regge trajectories applying to the COMPASS experiment. Combining the experimental data from COMPASS and our theoretical model we estimate the upper limit of ΓZc(4200)→J/ψπ to be of about 37 MeV. Moreover, the possibility to produce Λ_c^* (2940) at COMPASS is discussed. It seems one can try to search for this hadron in the missing mass spectrum since the t-channel is dominating for the Λ_c^* (2940) photoproduction.

  18. Opportunities with Polarized Hadron Beams

    NASA Astrophysics Data System (ADS)

    Lorenzon, Wolfgang

    2016-02-01

    Spin physics at future hadron facilities provide unique opportunities for the study of QCD well beyond those available at existing facilities. Opportunities with polarized protons in the Fermilab Main Injector are discussed that encompass polarized Drell-Yan scattering of unprecedented precision and also enable measurements of transversity, helicty and other transverse momentum dependent distributions. Forthcoming measurements at COMPASS-II that aim to test fundamental predictions of non-perturbative QCD, and complementary studies at RHIC-Spin that address, among others, open puzzles such as the sharing of the nucleon spin among its constituents are also discussed.

  19. Hadron physics in holographic QCD

    NASA Astrophysics Data System (ADS)

    Santra, A. B.; Lombardo, U.; Bonanno, A.

    2012-07-01

    Hadron physics deals with the study of strongly interacting subatomic particles such as neutrons, protons, pions and others, collectively known as baryons and mesons. Physics of strong interaction is difficult. There are several approaches to understand it. However, in the recent years, an approach called, holographic QCD, based on string theory (or gauge-gravity duality) is becoming popular providing an alternative description of strong interaction physics. In this article, we aim to discuss development of strong interaction physics through QCD and string theory, leading to holographic QCD.

  20. Heavy Hadron Spectroscopy at CDF

    SciTech Connect

    Fernandez Ramos, Juan Pablo

    2010-12-22

    We present recent CDF results on the properties of hadrons containing heavy quarks. These include measurements of charm and {Sigma}{sub b}{sup -{Sigma}}{sub b}*{sup -} baryon's masses, lifetimes and masses of {Omega}{sub b}{sup -,} {Xi}{sub b}{sup -} and B{sub c}{sup -} and a measurement of exclusive B{sup +}, B{sup 0} and {Lambda}{sub b} lifetimes as well as lifetime ratios (charge conjugate modes are implied throughout the text). We also summarize new measurements of exotic particles X(3872) and Y(4140).

  1. The theory of hadronic systems

    SciTech Connect

    Gibbs, W.R.

    1995-03-16

    This report briefly discusses progress on the following topics: isospin breaking in the pion-nucleon system; subthreshold amplitudes in the {pi}N system; neutron-proton charge-exchange; transparency in pion production; energy dependence of pion DCX; direct capture of pions into deeply bound atomic states; knock out of secondary components in the nucleus; radii of neutron distributions in nuclei; the hadronic double scattering operator; pion scattering and charge exchange from polarized nuclei; pion absorption in nuclei; modification of nucleon structure in nuclei; and antiproton annihilation in nuclei.

  2. Hadronic atoms and leptonic conservations

    SciTech Connect

    Kunselman, R.

    1989-01-01

    The major 1989 efforts have been mainly on two experiments at TRIUMF. One was a search for events where the leptonic flavor number conservation law would be violated. The second was an attempt to produce muonic hydrogen and muonic deuterium into a vacuum, and if there are found a adequate number of muons in the 2s state to measure precision energies. The minor efforts have been on the LAMPF experiment on lepton conservations which has consumed effort only in fabricating equipment, and on the completion of analyses from the experiments with hadronic atoms at LAMPF (pionic atoms) and BNL (kaonic and sigmonic atoms).

  3. Identified hadron spectra from PHOBOS

    NASA Astrophysics Data System (ADS)

    Veres, Gábor I.; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wyslouch, B.; Zhang, J.

    2004-08-01

    Transverse momentum spectra of pions, kaons and protons, as well as antiparticle to particle ratios near mid-rapidity from d+Au collisions at \\sqrt{s_{{\\rm NN}}} = 200\\,{\\rm GeV} have been measured by the PHOBOS experiment at RHIC. The transverse momentum range of particle identification was extended to beyond 3 GeV/c using the TOF detector and a new trigger system. The pseudorapidity dependence of the nuclear modification factor for charged hadrons in d+Au collisions is presented.

  4. Heavy hadron spectroscopy at CDF

    SciTech Connect

    Fernandez Ramos, Juan Pablo; /Madrid, CIEMAT

    2011-01-01

    We present recent CDF results on the properties of hadrons containing heavy quarks. These include measurements of charm and {Sigma}{sub b}{sup -}{Sigma}*{sub b}{sup -} baryon's masses, lifetimes and masses of {Omega}{sub b}{sup -}, {Xi}{sub b}{sup -} and B{sub c}{sup -} and a measurement of exclusive B{sup +}, B{sup 0} and {Lambda}{sub b} lifetimes as well as lifetime ratios (charge conjugate modes are implied throughout the text). We also summarize new measurements of exotic particles X(3872) and Y(4140).

  5. CALOCUBE: an approach to high-granularity and homogenous calorimetry for space based detectors

    NASA Astrophysics Data System (ADS)

    Bongi, M.; Adriani, O.; Albergo, S.; Auditore, L.; Bagliesi, M. G.; Berti, E.; Bigongiari, G.; Boezio, M.; Bonechi, L.; Bonechi, S.; Bonvicini, V.; Bottai, S.; Brogi, P.; Carotenuto, G.; Cassese, A.; Castellini, G.; Cattaneo, P. W.; Cauz, D.; Cumani, P.; D'Alessandro, R.; Detti, S.; Fasoli, M.; Gregorio, A.; Lamberto, A.; Lenzi, P.; Maestro, P.; Marrocchesi, P. S.; Mezzasalma, A.; Miritello, M.; Mori, N.; Papini, P.; Pauletta, G.; Rappazzo, G. F.; Rappoldi, A.; Ricciarini, S.; Spillantini, P.; Starodubtsev, O.; Sulaj, A.; Tiberio, A.; Trifirò, A.; Trimarchi, M.; Vannuccini, E.; Vedda, A.; Zampa, G.; Zampa, N.; Zerbo, B.

    2015-02-01

    Future space experiments dedicated to the observation of high-energy gamma and cosmic rays will increasingly rely on a highly performing calorimetry apparatus, and their physics performance will be primarily determined by the geometrical dimensions and the energy resolution of the calorimeter deployed. Thus it is extremely important to optimize its geometrical acceptance, the granularity, and its absorption depth for the measurement of the particle energy with respect to the total mass of the apparatus which is the most important constraint for a space launch. The proposed design tries to satisfy these criteria while staying within a total mass budget of about 1.6 tons. Calocube is a homogeneous calorimeter instrumented with Cesium iodide (CsI) crystals, whose geometry is cubic and isotropic, so as to detect particles arriving from every direction in space, thus maximizing the acceptance; granularity is obtained by filling the cubic volume with small cubic CsI crystals. The total radiation length in any direction is more than adequate for optimal electromagnetic particle identification and energy measurement, whilst the interaction length is at least suficient to allow a precise reconstruction of hadronic showers. Optimal values for the size of the crystals and spacing among them have been studied. The design forms the basis of a three-year R&D activity which has been approved and financed by INFN. An overall description of the system, as well as results from preliminary tests on particle beams will be described.

  6. The design of free structure granular mappings: the use of the principle of justifiable granularity.

    PubMed

    Pedrycz, Witold; Al-Hmouz, Rami; Morfeq, Ali; Balamash, Abdullah

    2013-12-01

    The study introduces a concept of mappings realized in presence of information granules and offers a design framework supporting the formation of such mappings. Information granules are conceptually meaningful entities formed on a basis of a large number of experimental input–output numeric data available for the construction of the model. We develop a conceptually and algorithmically sound way of forming information granules. Considering the directional nature of the mapping to be formed, this directionality aspect needs to be taken into account when developing information granules. The property of directionality implies that while the information granules in the input space could be constructed with a great deal of flexibility, the information granules formed in the output space have to inherently relate to those built in the input space. The input space is granulated by running a clustering algorithm; for illustrative purposes, the focus here is on fuzzy clustering realized with the aid of the fuzzy C-means algorithm. The information granules in the output space are constructed with the aid of the principle of justifiable granularity (being one of the underlying fundamental conceptual pursuits of Granular Computing). The construct exhibits two important features. First, the constructed information granules are formed in the presence of information granules already constructed in the input space (and this realization is reflective of the direction of the mapping from the input to the output space). Second, the principle of justifiable granularity does not confine the realization of information granules to a single formalism such as fuzzy sets but helps form the granules expressed any required formalism of information granulation. The quality of the granular mapping (viz. the mapping realized for the information granules formed in the input and output spaces) is expressed in terms of the coverage criterion (articulating how well the experimental data are

  7. State of hadron collider physics

    SciTech Connect

    Grannis, P.D. |

    1993-12-01

    The 9th Topical Workshop on Proton-Antiproton Collider Physics in Tsukuba Japan demonstrated clearly the enormous breadth of physics accessible in hadron cowders. Although no significant chinks were reported in the armor of the Standard Model, new results presented in this meeting have expanded our knowledge of the electroweak and strong interactions and have extended the searches for non-standard phenomena significantly. Much of the new data reported came from the CDF and D0 experiments at the Fermilab cowder. Superb operation of the Tevatron during the 1992-1993 Run and significant advances on the detector fronts -- in particular, the emergence of the new D0 detector as a productive physics instrument in its first outing and the addition of the CDF silicon vertex detector -- enabled much of this advance. It is noteworthy however that physics from the CERN collider experiments UA1 and UA4 continued to make a large impact at this meeting. In addition, very interesting summary talks were given on new results from HERA, cosmic ray experiments, on super-hadron collider physics, and on e{sup +}e{sup {minus}} experiments at LEP and TRISTAN. These summaries are reported in elsewhere in this volume.

  8. Novel Perspectives for Hadron Physics

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2012-03-09

    I discuss several novel and unexpected aspects of quantum chromodynamics. These include: (a) the nonperturbative origin of intrinsic strange, charm and bottom quarks in the nucleon at large x; the breakdown of pQCD factorization theorems due to the lensing effects of initial- and final-state interactions; (b) important corrections to pQCD scaling for inclusive reactions due to processes in which hadrons are created at high transverse momentum directly in the hard processes and their relation to the baryon anomaly in high-centrality heavy-ion collisions; and (c) the nonuniversality of quark distributions in nuclei. I also discuss some novel theoretical perspectives in QCD: (a) light-front holography - a relativistic color-confining first approximation to QCD based on the AdS/CFT correspondence principle; (b) the principle of maximum conformality - a method which determines the renormalization scale at finite order in perturbation theory yielding scheme independent results; (c) the replacement of quark and gluon vacuum condensates by 'in-hadron condensates' and how this helps to resolve the conflict between QCD vacuum and the cosmological constant.

  9. Drag and lift forces in granular media

    NASA Astrophysics Data System (ADS)

    Guillard, F.; Forterre, Y.; Pouliquen, O.

    2013-09-01

    Forces exerted on obstacles moving in granular media are studied. The experiment consists in a horizontal cylinder rotating around the vertical axis in a granular medium. Both drag forces and lift forces experienced by the cylinder are measured. The first striking result is obtained during the first half rotation, before the cylinder crosses its wake. Despite the symmetry of the object, a strong lift force is measured, about 20 times the buoyancy. The scaling of this force is studied experimentally. The second remarkable observation is made after several rotations. The drag force dramatically drops and becomes independent of depth, showing that it no longer scales with the hydrostatic pressure. The rotation of the cylinder induces a structure in the packing, which screens the weight of the grains above

  10. Spreading granular material with a blade

    NASA Astrophysics Data System (ADS)

    Dressaire, Emilie; Singh, Vachitar; Grimaldi, Emma; Sauret, Alban

    2015-11-01

    The spreading of a complex fluid with a blade is encountered in applications that range from the bulldozing of granular material in construction projects to the coating of substrates with fluids in industrial applications. This spreading process is also present in everyday life, when we use a knife to turn a lump of peanut butter into a thin layer over our morning toast. In this study, we rely on granular media in a model experiment to describe the three-dimensional spreading of the material. Our experimental set-up allows tracking the spreading of a sandpile on a translating flat surface as the blade remains fixed. We characterize the spreading dynamics and the shape of the spread fluid layer when varying the tilt of the blade, its spacing with the surface and its speed. Our findings suggest that it is possible to tune the spreading parameters to optimize the coating.

  11. Water drop dynamics on a granular layer

    NASA Astrophysics Data System (ADS)

    Llorens, Coraline; Biance, Anne-Laure; Ybert, Christophe; Pirat, Christophe; Liquids; Interfaces Team

    2015-11-01

    Liquid drop impacts, either on a solid surface or a liquid bath, have been studied for a while and are still subject of intense research. Less is known concerning impacts on granular layers that are shown to exhibit an intermediate situation between solid and liquid. In this study, we focus on water drop impacts on granular matter made of micrometer-sized spherical glass beads. In particular, we investigate the overall dynamics arising from the interplay between liquid and grains throughout the impact. Depending on the relevant parameters (impact velocity, drop and grain sizes, as well as their wetting properties), various behaviors are evidenced. In particular, the behavior of the beads at the liquid-gas interface (ball-bearing vs imbibition) is shown to greatly affect the spreading dynamics of the drop, as well as satellite droplets formation, beads ejection, and the final crater morphology.

  12. Nonlocal Constitutive Relation for Steady Granular Flow

    NASA Astrophysics Data System (ADS)

    Kamrin, Ken; Koval, Georg

    2012-04-01

    Extending recent modeling efforts for emulsions, we propose a nonlocal fluidity relation for flowing granular materials, capturing several known finite-size effects observed in steady flow. We express the local Bagnold-type granular flow law in terms of a fluidity ratio and then extend it with a particular Laplacian term that is scaled by the grain size. The resulting model is calibrated against a sequence of existing discrete element method data sets for two-dimensional annular shear, where it is shown that the model correctly describes the divergence from a local rheology due to the grain size as well as the rate-independence phenomenon commonly observed in slowly flowing zones. The same law is then applied in two additional inhomogeneous flow geometries, and the predicted velocity profiles are compared against corresponding discrete element method simulations utilizing the same grain composition as before, yielding favorable agreement in each case.

  13. Brownian motor in a granular medium

    NASA Astrophysics Data System (ADS)

    Balzan, R.; Dalton, F.; Loreto, V.; Petri, A.; Pontuale, G.

    2011-03-01

    In this work we experimentally study the behavior of a freely rotating asymmetric probe immersed in a vibrated granular medium. For a wide variety of vibration conditions the probe exhibits a steady rotation whose direction is constant with respect to the asymmetry. By changing the vibration amplitude and by filtering the noise in different frequency bands we show that the velocity of rotation depends not only on the RMS acceleration Γ, but also on the amount of energy provided to two separate frequency bands, which are revealed to be important for the dynamics of the granular medium: The first band governs the transfer of energy from the grains to the probe, and the second affects the dynamics by altering the viscosity of the vibro-fluidized material.

  14. Heat flux in a granular gas

    NASA Astrophysics Data System (ADS)

    Brey, J. J.; Ruiz-Montero, M. J.

    2012-11-01

    A peculiarity of the hydrodynamic Navier-Stokes equations for a granular gas is the modification of the Fourier law, with the presence of an additional contribution to the heat flux that is proportional to the density gradient. Consequently, the constitutive relation involves, in the case of a one-component granular gas, two transport coefficients: the usual (thermal) heat conductivity and a diffusive heat conductivity. A very simple physical interpretation of this effect, in terms of the mean free path and the mean free time is provided. It leads to the modified Fourier law with an expression for the diffusive Fourier coefficient that differs in a factor of the order of unity from the expression obtained by means of the inelastic Boltzmann equation. Also, some aspects of the Chapman-Enskog computation of the new transport coefficients as well as of the comparison between simulation results and theory are discussed.

  15. Writing in the granular gel medium

    PubMed Central

    Bhattacharjee, Tapomoy; Zehnder, Steven M.; Rowe, Kyle G.; Jain, Suhani; Nixon, Ryan M.; Sawyer, W. Gregory; Angelini, Thomas E.

    2015-01-01

    Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies. PMID:26601274

  16. Impact of liquid droplets on granular media

    NASA Astrophysics Data System (ADS)

    Delon, G.; Terwagne, D.; Dorbolo, S.; Vandewalle, N.; Caps, H.

    2011-10-01

    The crater formation due to the impact of a water droplet onto a granular bed has been experimentally investigated. Three parameters were tuned: the impact velocity, the size of the droplet, and the size of the grains. The aim is to determine the influence of the kinetic energy on the droplet pattern. The shape of the crater depends on the kinetic energy at the moment the droplet starts to impact the bed. The spreading and recession of the liquid during the impact were carefully analyzed from the dynamical point of view, using image analysis of high-speed video recordings. The different observed regimes are characterized by the balance between the impregnation time of the water by the granular bed by the water and the capillary time responsible for the recession of the drop.

  17. Erosion and flow of hydrophobic granular materials

    NASA Astrophysics Data System (ADS)

    Utter, Brian; Benns, Thomas; Mahler, Joseph

    2013-11-01

    We experimentally investigate submerged granular flows of hydrophobic and hydrophilic grains both in a rotating drum geometry and under erosion by a surface water flow. While slurry and suspension flows are common in nature and industry, effects of surface chemistry on flow behavior have received relatively little attention. In the rotating drum , we use varying concentrations of hydrophobic and hydrophilic grains of sand submerged in water rotated at a constant angular velocity. Sequential images of the resulting avalanches are taken and analyzed. High concentrations of hydrophobic grains result in an effectively cohesive interaction between the grains forming aggregates, with aggregate size and repose angle increasing with hydrophobic concentration. However, the formation and nature of the aggregates depends significantly on the presence of air in the system. We present results from a related experiment on erosion by a surface water flow designed to characterize the effects of heterogeneous granular surfaces on channelization and erosion. Supported by NSF CBET Award 1067598.

  18. Erosion and flow of hydrophobic granular materials

    NASA Astrophysics Data System (ADS)

    Utter, Brian; Benns, Thomas; Foltz, Benjamin; Mahler, Joseph

    2015-03-01

    We experimentally investigate submerged granular flows of hydrophobic and hydrophilic grains both in a rotating drum geometry and under erosion by a surface water flow. While slurry and suspension flows are common in nature and industry, effects of surface chemistry on flow behavior have received relatively little attention. In the rotating drum, we use varying concentrations of hydrophobic and hydrophilic grains of sand submerged in water rotated at a constant angular velocity. Sequential images of the resulting avalanches are taken and analyzed. High concentrations of hydrophobic grains result in an effectively cohesive interaction between the grains forming aggregates, with aggregate size and repose angle increasing with hydrophobic concentration. However, the formation and nature of the aggregates depends significantly on the presence of air in the system. We present results from a related experiment on erosion by a surface water flow designed to characterize the effects of heterogeneous granular surfaces on channelization and erosion.

  19. Writing in the granular gel medium.

    PubMed

    Bhattacharjee, Tapomoy; Zehnder, Steven M; Rowe, Kyle G; Jain, Suhani; Nixon, Ryan M; Sawyer, W Gregory; Angelini, Thomas E

    2015-09-01

    Gels made from soft microscale particles smoothly transition between the fluid and solid states, making them an ideal medium in which to create macroscopic structures with microscopic precision. While tracing out spatial paths with an injection tip, the granular gel fluidizes at the point of injection and then rapidly solidifies, trapping injected material in place. This physical approach to creating three-dimensional (3D) structures negates the effects of surface tension, gravity, and particle diffusion, allowing a limitless breadth of materials to be written. With this method, we used silicones, hydrogels, colloids, and living cells to create complex large aspect ratio 3D objects, thin closed shells, and hierarchically branched tubular networks. We crosslinked polymeric materials and removed them from the granular gel, whereas uncrosslinked particulate systems were left supported within the medium for long times. This approach can be immediately used in diverse areas, contributing to tissue engineering, flexible electronics, particle engineering, smart materials, and encapsulation technologies. PMID:26601274

  20. Transport Coefficients of Interacting Hadrons

    NASA Astrophysics Data System (ADS)

    Wiranata, Anton

    A detailed quantitative comparison between the results of shear viscosities from the Chapman-Enskog and Relaxation Time methods is performed for the following test cases with specified elastic differential cross sections between interacting hadrons: (1) The non-relativistic, relativistic and ultra-relativistic hard sphere gas with angle and energy independent differential cross section sigma = a2/4, where a is the hard sphere radius, (2) The Maxwell gas with sigma(g, theta) = mGamma(theta)/2g, where m is the mass of the heat bath particles, Gamma(theta) is an arbitrary function of theta, and g is the relative velocity, (3) Chiral pions for which the t-averaged cross section sigma = s/(64pi2 f4p ) x (1 + 1/3 x cos2 theta), where s and t are the usual Mandelstam variables and fpi is the pion-decay constant, and (4) Massive pions for which the differential elastic cross section is taken from experiments. Quantitative results of the comparative study conducted revealed that • the extent of agreement (or disagreement) depends very sensitively on the energy dependence of the differential cross sections employed, stressing the need to combine all available experimental knowledge concerning differential cross sections for low mass hadrons and to supplement it with theoretical guidance for the as yet unknown cross sections so that the temperature dependent shear viscosity to entropy ratio can be established for use in viscous hydordynamics. • The result found for the ultra-relativistic hard sphere gas for which the shear viscosity etas = 1.2676 k BT c--1/(pia 2) offers the opportunity to validate ultra-relativistic quantum molecular dynamical (URQMD) codes that employ Green-Kubo techniques. • shear viscosity receives only small contributions from number changing inelastic processes. The dependence of the bulk viscosity on the adiabatic speed of sound is studied in depth highlighting why only hadrons in the intermediate relativistic regime contribute the most to the

  1. Critical Phase Transitions in Vibrated Granular Media

    NASA Astrophysics Data System (ADS)

    Wortel, Geert; Dauchot, Olivier; van Hecke, Martin

    2013-03-01

    Granular media, such as sand, jam under low stresses but yield and flow when stressed sufficiently. We present experiments that uncover that weak vibrations qualitatively modify the nature of this yielding transition from 1st to 2nd order: when the vibration strength, which plays a role similar to temperature, is raised sufficiently, the yielding transition becomes continuous. At the critical point, we find diverging fluctuations, growing timescales and the emergence of a length scale: hallmarks of criticality never seen before in sand.

  2. Swimming in a granular frictional fluid

    NASA Astrophysics Data System (ADS)

    Goldman, Daniel

    2012-02-01

    X-ray imaging reveals that the sandfish lizard swims within granular media (sand) using axial body undulations to propel itself without the use of limbs. To model the locomotion of the sandfish, we previously developed an empirical resistive force theory (RFT), a numerical sandfish model coupled to an experimentally validated Discrete Element Method (DEM) model of the granular medium, and a physical robot model. The models reveal that only grains close to the swimmer are fluidized, and that the thrust and drag forces are dominated by frictional interactions among grains and the intruder. In this talk I will use these models to discuss principles of swimming within these granular ``frictional fluids". The empirical drag force laws are measured as the steady-state forces on a small cylinder oriented at different angles relative to the displacement direction. Unlike in Newtonian fluids, resistive forces are independent of speed. Drag forces resemble those in viscous fluids while the ratio of thrust to drag forces is always larger in the granular media than in viscous fluids. Using the force laws as inputs, the RFT overestimates swimming speed by approximately 20%. The simulation reveals that this is related to the non-instantaneous increase in force during reversals of body segments. Despite the inaccuracy of the steady-state assumption, we use the force laws and a recently developed geometric mechanics theory to predict optimal gaits for a model system that has been well-studied in Newtonian fluids, the three-link swimmer. The combination of the geometric theory and the force laws allows us to generate a kinematic relationship between the swimmer's shape and position velocities and to construct connection vector field and constraint curvature function visualizations of the system dynamics. From these we predict optimal gaits for forward, lateral and rotational motion. Experiment and simulation are in accord with the theoretical prediction, and demonstrate that

  3. On vibrational diffusion segregation in granular media

    NASA Astrophysics Data System (ADS)

    Blekhman, I. I.; Blekhman, L. I.; Vaisberg, L. A.; Vasilkov, V. B.; Yakimova, K. S.

    2016-01-01

    In this paper, the definition and description of vibrational diffusion (gradient) segregation of the bulk materials have been provided. The results of the experimental studies of this kind of segregation are described. This technique can be very useful for creation of entirely new high effective machines for granular separation. The results of theoretical investigation are presented. In this investigation, the diffusion equation, in which random and deterministic parameters are taken into consideration, has been used.

  4. Full-scale granular sludge Anammox process.

    PubMed

    Abma, W R; Schultz, C E; Mulder, J W; van der Star, W R L; Strous, M; Tokutomi, T; van Loosdrecht, M C M

    2007-01-01

    The start-up of the first full scale Anammox reactor is complete. The reactor shows stable operation, even at loading rates of 10 kg N/m3.d. This performance is the result of the formation of Anammox granules, which have a high density and settling velocities exceeding 100 m/h. With this performance, the Anammox granular sludge technology has been proven on full scale. PMID:17546966

  5. Freely evolving self gravitating granular gas

    NASA Astrophysics Data System (ADS)

    Kumari, Shikha; Ahmad, Syed Rashid

    2016-05-01

    Granular Materials are composed of large number of discrete solid particles. They can be considered solid, liquid or gas depending on movement of the constituting particles and are characterized by loss of energy whenever grains come in contact. We are studying the dynamics of such materials using computer simulations. In particular, we are studying systems that interact with long-range gravitational force in addition to dissipative contact forces. Our focus is on evolution morphology and clustering of particles in this system.

  6. Di-hadron production at Jefferson Lab

    SciTech Connect

    Anefalos Pereira, Sergio; et. al.,

    2014-10-01

    Semi-inclusive deep inelastic scattering (SIDIS) has been used extensively in recent years as an important testing ground for QCD. Studies so far have concentrated on better determination of parton distribution functions, distinguishing between the quark and antiquark contributions, and understanding the fragmentation of quarks into hadrons. Hadron pair (di-hadron) SIDIS provides information on the nucleon structure and hadronization dynamics that complement single hadron SIDIS. Di-hadrons allow the study of low- and high-twist distribution functions and Dihadron Fragmentation Functions (DiFF). Together with the twist-2 PDFs ( f1, g1, h1), the Higher Twist (HT) e and hL functions are very interesting because they offer insights into the physics of the largely unexplored quark-gluon correlations, which provide access into the dynamics inside hadrons. The CLAS spectrometer, installed in Hall-B at Jefferson Lab, has collected data using the CEBAF 6 GeV longitudinally polarized electron beam on longitudinally polarized solid NH3 targets. Preliminary results on di-hadron beam-, target- and double-spin asymmetries will be presented.

  7. Status and Prospects for Hadron Production Experiments

    SciTech Connect

    Schroeter, Raphaeel

    2010-03-30

    The latest results from the HARP, MIPP and NA61 Hadron Production Experiments are reviewed and their implications for neutrinos physics experiments are discussed. We emphasize three neutrino sources: accelerator-based neutrino beams, advanced neutrino sources and atmospheric neutrinos. Finally, prospects from additional forthcoming hadron production measurements are presented.

  8. Hadron production at PEP/PETRA

    SciTech Connect

    Yamamoto, H.

    1985-12-01

    Recent results on hadron production in e/sup +/e/sup -/ annihilation at PEP and PETRA are summarized. The topics included are: (1) inclusive hadron production, (2) gluon vs quark jet, (3) analysis of 3 jet events and (4) p - anti p correlations. Experimental data are compared with predictions of several models to reveal underlying physics. 47 refs., 18 figs.

  9. Variation of transverse momentum in hadronic collisions

    NASA Technical Reports Server (NTRS)

    Saint Amand, J.; Uritam, R. A.

    1975-01-01

    The paper presents a detailed parameterization of the transverse momentum in hadronic collisions on multiplicity and on beam momentum. Hadronic collisions are considered at energies below the ultra-high energy domain, on the basis of an uncertainty relation and a naive eikonal model with an impact-parameter-dependent multiplicity.

  10. A Survey of Hadron Therapy Accelerator Technologies.

    SciTech Connect

    PEGGS,S.; SATOGATA, T.; FLANZ, J.

    2007-06-25

    Hadron therapy has entered a new age [1]. The number of facilities grows steadily, and 'consumer' interest is high. Some groups are working on new accelerator technology, while others optimize existing designs by reducing capital and operating costs, and improving performance. This paper surveys the current requirements and directions in accelerator technology for hadron therapy.

  11. Legged-locomotion on inclined granular media

    NASA Astrophysics Data System (ADS)

    Rieser, Jennifer; Qian, Feifei; Goldman, Daniel

    Animals traverse a wide variety of complex environments, including situations in which the ground beneath them can yield (e.g. dry granular media in desert dunes). Locomotion strategies that are effective on level granular media can fail when traversing a granular slope. Taking inspiration from successful legged-locomotors in sandy, uneven settings, we explore the ability of a small (15 cm long, 100 g), six-c-shaped legged robot to run uphill in a bed of 1-mm-diameter poppy seeds, using an alternating tripod gait. Our fully automated experiments reveal that locomotor performance can depend sensitively on both environmental parameters such as the inclination angle and volume fraction of the substrate, and robot morphology and control parameters like leg shape, step frequency, and the friction between the feet of the robot and the substrate. We assess performance by measuring the average speed of the robot, and we find that the robot tends to perform better at higher step frequency and lower inclination angles, and that average speed decreases more rapidly with increasing angle for higher step frequency.

  12. Wet granular materials submitted to thermal cycling

    NASA Astrophysics Data System (ADS)

    Lumay, Geoffroy; Ludewig, Francois; Fiscina, Jorge; Pakpour, Maryam; Vandewalle, Nicolas; Dorbolo, Stephane

    2015-03-01

    Many phenomenons observed in nature are related to the particular behavior of wet granular materials submitted to temperature cycling: ice-lens formation in soil leading to frost heaving, landslides, structures formation in permafrost, stone heave and possibly some geological formations observed on Mars. We present experimental results concerning the effect of thermal cycling on the packing fraction of equal spheres with the presence of water. First, the case corresponding to completely immersed granular piles is considered. Afterward, the effect of thermal cycling on unsaturated granular piles is discussed. The pile is submitted to temperature cycling ranging from T1 to T2. If the temperature is always higher than 4°C, the temperature increase (or decrease) induces a dilatation (or contraction) of the grains and of the water. We show that the packing fraction variation is mainly related to water dilatation and contraction. If the temperature decreases under 0°C during a cycle, the water situated between the grains experiences a strong dilatation during the freezing step and a contraction during the ice melting step. In this case, we show how the freeze-thaw transition affects the packing fraction of the pile.

  13. Oblique impact of dense granular sheets

    NASA Astrophysics Data System (ADS)

    Ellowitz, Jake; Guttenberg, Nicholas; Jaeger, Heinrich M.; Nagel, Sidney R.; Zhang, Wendy W.

    2013-11-01

    Motivated by experiments showing impacts of granular jets with non-circular cross sections produce thin ejecta sheets with anisotropic shapes, we study what happens when two sheets containing densely packed, rigid grains traveling at the same speed collide asymmetrically. Discrete particle simulations and a continuum frictional fluid model yield the same steady-state solution of two exit streams emerging from incident streams. When the incident angle Δθ is less than Δθc =120° +/-10° , the exit streams' angles differ from that measured in water sheet experiments. Below Δθc , the exit angles from granular and water sheet impacts agree. This correspondence is surprising because 2D Euler jet impact, the idealization relevant for both situations, is ill posed: a generic Δθ value permits a continuous family of solutions. Our finding that granular and water sheet impacts evolve into the same member of the solution family suggests previous proposals that perturbations such as viscous drag, surface tension or air entrapment select the actual outcome are not correct. Currently at Department of Physics, University of Oregon, Eugene, OR 97403.

  14. Characterization of undulatory locomotion in granular media

    NASA Astrophysics Data System (ADS)

    Peng, Zhiwei; Pak, On Shun; Elfring, Gwynn

    2015-11-01

    Undulatory locomotion is ubiquitous in nature, from the swimming of flagellated microorganisms in biological fluids, to the slithering of snakes on land, or the locomotion of sandfish lizards in sand. Analysis of locomotion in granular materials is relatively less developed compared with fluids partially due to a lack of validated force models but a recently proposed resistive force theory (RFT) in granular media has been shown useful in studying the locomotion of a sand-swimming lizard. Here we employ this model to investigate the swimming characteristics of an undulating slender filament of both finite and infinite length. For infinite swimmers, similar to results in viscous fluids, the sawtooth waveform is found to be optimal for propulsion speed at a given power consumption. We also compare the swimming characteristics of sinusoidal and sawtooth swimmers with swimming in viscous fluids. More complex swimming dynamics emerge when the assumption of an infinite swimmer is removed. In particular, we characterize the effects of drifting and pitching in terms of propulsion speed and efficiency for a finite sinusoidal swimmer. The results complement our understanding of undulatory locomotion and provide insights into the effective design of locomotive systems in granular media.

  15. Dynamic shear jamming in granular suspensions

    NASA Astrophysics Data System (ADS)

    Peters, Ivo; Majumdar, Sayantan; Jaeger, Heinrich

    2014-11-01

    Jamming by shear allows a frictional granular packing to transition from an unjammed state into a jammed state while keeping the system volume and average packing fraction constant. Shear jamming of dry granular media can occur quasi-statically, but boundaries are crucial to confine the material. We perform experiments in aqueous starch suspension where we apply shear using a rheometer with a large volume (400 ml) cylindrical Couette cell. In our suspensions the packing fraction is sufficiently low that quasi-static deformation does not induce a shear jammed state. Applying a shock-like deformation however, will turn the suspension into a jammed solid. A fully jammed state is reached within tens of microseconds, and can be sustained for at least several seconds. High speed imaging of the initial process reveals a jamming front propagating radially outward through the suspension, while the suspension near the outer boundary remains quiescent. This indicates that granular suspensions can be shear jammed without the need of confining solid boundaries. Instead, confinement is most likely provided by the dynamics in the front region.

  16. Unified force law for granular impact cratering

    NASA Astrophysics Data System (ADS)

    Katsuragi, Hiroaki; Durian, Douglas J.

    2007-06-01

    Experiments on the low-speed impact of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter. Observations have been interpreted in terms of conflicting stopping forces: product of powers of projectile depth and speed; linear in speed; constant, proportional to the initial impact speed; and proportional to depth. This is reminiscent of high-speed ballistics impact in the nineteenth and twentieth centuries, when a plethora of empirical rules were proposed. To make progress, we developed a means to measure projectile dynamics with 100nm and 20μs precision. For a 1-inch-diameter steel sphere dropped from a wide range of heights into non-cohesive glass beads, we reproduce previous observations either as reasonable approximations or as limiting behaviours. Furthermore, we demonstrate that the interaction between the projectile and the medium can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction. Thus, we achieve a unified description of low-speed impact phenomena and show that the complex response of granular materials to impact, although fundamentally different from that of liquids and solids, can be simply understood.

  17. Mechanics of Granular Materials (MGM) Test Cell

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A test cell for Mechanics of Granular Materials (MGM) experiment is tested for long-term storage with water in the system as plarned for STS-107. This view shows the compressed sand column with the protective water jacket removed. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that cannot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: University of Colorado at Boulder

  18. Mechanics of Granular Materials (MGM) Test Cell

    NASA Technical Reports Server (NTRS)

    2000-01-01

    A test cell for Mechanics of Granular Materials (MGM) experiment is tested for long-term storage with water in the system as plarned for STS-107. This view shows the top of the sand column with the metal platten removed. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that cannot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: University of Colorado at Boulder

  19. Mechanics of Granular Materials (MGM) Test Cell

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A test cell for Mechanics of Granular Materials (MGM) experiment is shown approximately 20 and 60 minutes after the start of an experiment on STS-89. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: NASA/Marshall Space Flight Center (MSFC)

  20. Mechanics of Granular Materials (MGM) Cell

    NASA Technical Reports Server (NTRS)

    1996-01-01

    One of three Mechanics of Granular Materials (MGM) test cells after flight on STS-79 and before impregnation with resin. Note that the sand column has bulged in the middle, and that the top of the column is several inches lower than the top of the plastic enclosure. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: University of Colorado at Boulder

  1. Mechanics of Granular Materials (MGM) Flight Hardware

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A test cell for the Mechanics of Granular Materials (MGM) experiment is shown in its on-orbit configuration in Spacehab during preparations for STS-89. The twin locker to the left contains the hydraulic system to operate the experiment. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Note: Because the image on the screen was muted in the original image, its brightness and contrast are boosted in this rendering to make the test cell more visible. Credit: NASA/Marshall Space Flight Center (MSFC)

  2. Mechanics of Granular Materials Test Cell

    NASA Technical Reports Server (NTRS)

    1998-01-01

    A test cell for Mechanics of Granular Materials (MGM) experiment is shown from all three sides by its video camera during STS-89. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. Mechanics of Granular Materials (MGM) experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditons that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. Credit: NASA/Marshall Space Flight Center (MSFC)

  3. Force transmission in cohesive granular media

    NASA Astrophysics Data System (ADS)

    Radjai, Farhang; Topin, Vincent; Richefeu, Vincent; Voivret, Charles; Delenne, Jean-Yves; Azéma, Emilien; El Youssoufi, Said

    2010-05-01

    We use numerical simulations to investigate force and stress transmission in cohesive granular media covering a wide class of materials encountered in nature and industrial processing. The cohesion results either from capillary bridges between particles or from the presence of a solid binding matrix filling fully or partially the interstitial space. The liquid bonding is treated by implementing a capillary force law within a debonding distance between particles and simulated by the discrete element method. The solid binding matrix is treated by means of the Lattice Element Method (LEM) based on a lattice-type discretization of the particles and matrix. Our data indicate that the exponential fall-off of strong compressive forces is a generic feature of both cohesive and noncohesive granular media both for liquid and solid bonding. The tensile forces exhibit a similar decreasing exponential distribution, suggesting that this form basically reflects granular disorder. This is consistent with the finding that not only the contact forces but also the stress components in the bulk of the particles and matrix, accessible from LEM simulations in the case of solid bonding, show an exponential fall-off. We also find that the distribution of weak compressive forces is sensitive to packing anisotropy, particle shape and particle size distribution. In the case of wet packings, we analyze the self-equilibrated forces induced by liquid bonds and show that the positive and negative particle pressures form a bi-percolating structure.

  4. Energy dissipation in sheared granular flows

    SciTech Connect

    Karion, A.; Hunt, M.L.

    1999-11-01

    Granular material flows describe flows of solid particles in which the interstitial fluid plays a negligible role in the flow mechanics. Examples include the transport of coal, food products, detergents, pharmaceutical tablets, and toner particles in high-speed printers. Using a two-dimensional discrete element computer simulation of a bounded, gravity-free Couette flow of particles, the heat dissipation rate per unit area is calculated as a function of position in the flow as well as overall solid fraction. The computation results compare favorably with the kinetic theory analysis for rough disks. The heat dissipation rate is also measured for binary mixtures of particles for different small to large solid fraction ratios, and for diameter ratios of ten, five, and two. The dissipation rates increase significantly with overall solid fraction as well as local strain rates and granular temperatures. The thermal energy equation is solved for a Couette flow with one adiabatic wall and one at constant temperature. Solutions use the simulation measurements of the heat dissipation rate, solid fraction, and granular temperature to show that the thermodynamic temperature increases with solid fraction and decreases with particle conductivity. In mixtures, both the dissipation rate and the thermodynamic temperature increase with size ratio and with decreasing ratio of small to large particles.

  5. Electrical charging in shaken granular media

    NASA Astrophysics Data System (ADS)

    Nordsiek, Freja; Lathrop, Daniel

    2015-03-01

    Collisional electrification of granular particles and the resulting electric fields are seen but poorly understood in sand storms, volcanic ash clouds, thunderstorms, and thundersnow. We present results on the electrical charging of granular media (100 micron to 1 mm in size) shaken between two conducting plates. The voltage between the plates was measured. We saw particle electrification through capacitive coupling with the plates and electrical discharges for a diverse class of materials: polystyrene (polymer), soda-lime glass (glass), 69%:31% ZrO2:SiO2 (ceramic), and aluminum (metal). We found 1) a monotonic increase in charging with shaking strength, 2) a threshold in the number of particles to see charging of about the number of particles needed to form a monolayer on the plate, 3) material and diameter differences causing an order of magnitude spread in measured signal but little difference between mono-material sets with one size range and bi-material and/or bi-size range set combinations, and 4) long time scale transients. We argue that while two-body collisions and the physical properties of the particles (material and size) are relevant, collective phenomena are a necessary part of explaining natural charging of granular flows. We gratefully acknowledge funding from the Julien Schwinger Foundation.

  6. The Sakharov Experiment Revisited for Granular Materials

    NASA Astrophysics Data System (ADS)

    Vogler, Tracy

    2013-06-01

    Sakharov and co-workers in 1965 proposed an experiment in which a sinusoidal perturbation in a planar wave evolves as it travels through a material. More recent, Liu and co-workers utilized gas gun techniques rather than explosives to drive the shock wave, resulting in a better defined input. The technique has been applied to liquids such as water and mercury as well as solids such as aluminum. All analyses of the experiments conducted to date have utilized a viscous fluid approach, even for the solids. Here, the concept of the decay of a perturbation in a shock wave is revisited and applied to granular materials. Simulations utilizing continuum models for the granular materials as well as mesoscale models in which individual particles are resolved are utilized. It is found that the perturbation decay is influenced by the strength (deviatoric behavior) used in the continuum model. In the mesocale calculations, the simulation parameters as well as the computational approach influence the results. Finally, initial experimental results for the technique using granular tungsten carbide are presented. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  7. Mechanics of Granular Materials-3 (MGM-3)

    NASA Technical Reports Server (NTRS)

    Sture, Stein; Alshibi, Khalid; Guynes, Buddy (Technical Monitor)

    2002-01-01

    Scientists are going to space to understand how earthquakes and other forces disturb grains of soil and sand. They will examine how the particle arrangement and structure of soils, grains and powders are changed by external forces and gain knowledge about the strength, stiffness and volume changes properties of granular materials at low pressures. The Mechanics of Granular Materials (MGM) experiment uses the microgravity of orbit to test sand columns under conditions that cannot be obtained in experiments on Earth. Research can only go so far on Earth because gravity-induced stresses complicate the analysis and change loads too quickly for detailed analysis. This new knowledge will be applied to improving foundations for buildings, managing undeveloped land, and handling powdered and granular materials in chemical, agricultural, and other industries. NASA wants to understand the way soil behaves under different gravity levels so that crews can safely build habitats on Mars and the Moon. Future MGM experiments will benefit from extended tests aboard the International Space Station, including experiments under simulated lunar and Martian gravity in the science centrifuge.

  8. Moving Granular Bed Filter Development Program

    SciTech Connect

    Wilson, K.B.; Haas, J.C.; Eshelman, M.B.

    1992-01-01

    The granular bed filter was developed through low pressure, high temperature (1600[degrees]F) testing in the late 1970's and early 1980's'. Collection efficiencies over 99% were obtained. In 1988, high pressure, high temperature testing was completed at New York University, Westbury, N.Y., utilizing a coal-fired pressurized, fluidized bed combustor. High particulate removal efficiencies were confirmed as it was shown that both New Source Performance Standards and turbine tolerance limits could be met. The early scale-up work of the granular bed filter indicated potential limitations due to size, cost, and mechanical complexity. These limitations were addressed in the present program by utilizing the information gained from the filter development up through the NYU test program to reassess the commercial approach. Two studies were chosen for developing conceptual designs and cost estimates of the commercial sized filters. One is the economic study of the 250 MWe, second generation pressurized fluidized bed combustion plant defined by Foster Wheeler. This plant originally included cross-flow filters for hot gas cleanup. The other plant under study is a 100 MWe, airblown KRW gasifier. A cross-flow inter was utilized for gas stream cleanup in this study also. Granular bed and ceramic candle filters were substituted for the cross-flow filters in both these plants, and the resulting cost of electricity (COE) is compared.

  9. Moving Granular Bed Filter Development Program

    SciTech Connect

    Wilson, K.B.; Haas, J.C.; Eshelman, M.B.

    1992-11-01

    The granular bed filter was developed through low pressure, high temperature (1600{degrees}F) testing in the late 1970`s and early 1980`s`. Collection efficiencies over 99% were obtained. In 1988, high pressure, high temperature testing was completed at New York University, Westbury, N.Y., utilizing a coal-fired pressurized, fluidized bed combustor. High particulate removal efficiencies were confirmed as it was shown that both New Source Performance Standards and turbine tolerance limits could be met. The early scale-up work of the granular bed filter indicated potential limitations due to size, cost, and mechanical complexity. These limitations were addressed in the present program by utilizing the information gained from the filter development up through the NYU test program to reassess the commercial approach. Two studies were chosen for developing conceptual designs and cost estimates of the commercial sized filters. One is the economic study of the 250 MWe, second generation pressurized fluidized bed combustion plant defined by Foster Wheeler. This plant originally included cross-flow filters for hot gas cleanup. The other plant under study is a 100 MWe, airblown KRW gasifier. A cross-flow inter was utilized for gas stream cleanup in this study also. Granular bed and ceramic candle filters were substituted for the cross-flow filters in both these plants, and the resulting cost of electricity (COE) is compared.

  10. Self-Organization in Granular Slurries

    NASA Astrophysics Data System (ADS)

    Ottino, Julio M.; Jain, Nitin; Lueptow, Richard M.; Khakhar, Devang V.

    2000-11-01

    Mixtures of tumbled granular materials under flow exhibit various intriguing types of un-mixing or self-organization. Small differences in particles' density, size or shape may trigger the effect. Nearly all studies to date have addressed the case of dry granular media, where the interparticle fluid is typically air. Here we report the existence of self-organization in wet granular media or slurries, mixtures of particles of different sizes dispersed in a lower density liquid. Technological examples appear in cement, ceramics, fine chemicals, and in the food industry; examples in nature appear in evolution of landslides and transport in river sediments. In spite of significantly different physics at the particle level, both axial banding (alternating bands rich in small and large particles in a long rotating cylinder) and radial segregation (in quasi 2D containers) are observed in slurries. However, axial segregation is significantly faster and the spectrum of outcomes is richer. Moreover, experiments with suitable fluids, reveal, for the first time, the internal structure of axially segregated systems, something that up to now has been accessible only via magnetic resonance imaging (MRI) experimentation.

  11. Medium modification of hadron masses and the thermodynamics of the hadron resonance gas model

    NASA Astrophysics Data System (ADS)

    Kadam, Guru Prakash; Mishra, Hiranmaya

    2016-02-01

    We study the effect of temperature (T ) and baryon density (μ ) dependent hadron masses on the thermodynamics of hadronic matter. We use linear scaling rule in terms of constituent quark masses for all hadrons except for light mesons. T - and μ -dependent constituent quark masses and the light meson masses are computed using 2 +1 flavor Nambu-Jona-Lasinio (NJL) model. We compute the thermodynamical quantities of hadronic matter within excluded volume hadron resonance gas model (EHRG) with these T - and μ -dependent hadron masses. We confront the thermodynamical quantities with the lattice quantum chromodynamics (LQCD) at μ =0 GeV . Further, we comment on the effect of T - and μ -dependent hadron masses on the transport properties near the transition temperature (Tc).

  12. HADRON05 Summary: Heavy Quark Hadrons and Theory

    NASA Astrophysics Data System (ADS)

    Barnes, T.

    2006-02-01

    This HADRON05 summary covers the topics of (1) mesons containing heavy quarks, and (2) theory. The new material discussed here is taken mainly from plenary presentations. We specifically emphasize new or recent results in spectroscopy that are likely to appear in future editions of the PDG. An exception is made for the pentaquark, which was withdrawn at this meeting. We undoubtedly have something important to (re)learn about multiquarks from the pentaquark saga, and this merits a phrase in Portuguese. The three general areas we consider are: I. QQ¯ spectroscopy, II. Qq¯ spectroscopy, and III. lessons from the pentaquark. Finally, in Section IIIb. we conclude with "Our moment of Zen".

  13. Hadron interactions and exotic hadrons from lattice QCD

    NASA Astrophysics Data System (ADS)

    Ikeda, Yoichi

    2014-09-01

    One of the interesting subjects in hadron physics is to look for the multiquark configurations. One of candidates is the H-dibaryon (udsuds), and the possibility of the bound H-dibaryon has been recently studied from lattice QCD. We also extend the HAL QCD method to define potentials on the lattice between baryons to meson-meson systems including charm quarks to search for the bound tetraquark Tcc (ud c c) and Tcs (ud c s). In the presentation, after reviewing the HAL QCD method, we report the results on the H-dibaryon, the tetraquark Tcc (ud c c) and Tcs (ud c s), where we have employed the relativistic heavy quark action to treat the charm quark dynamics with pion masses, mπ = 410, 570, 700 MeV.

  14. Nuclear Effects in Hadron Production at HERMES

    SciTech Connect

    Bianchi, Nicola

    2007-11-19

    The influence of the nuclear medium on the lepto-production of hadrons was studied in semi-inclusive deep-inelastic scattering off several nuclear targets. In particular, at the HERMES experiment at DESY, the differential multiplicity for nuclei relative to that of deuterium has been measured for the first time for various identified hadrons ({pi}{sup +}, {pi}{sup -}, {pi}{sup 0}, K{sup +}, K{sup -}, p and anti-p) as a function of the virtual photon energy {nu}, the fraction z of this energy transferred to the hadron, and the hadron transverse momentum squared p{sub t}{sup 2}. The distribution of the hadron transverse momentum is broadened towards high p{sub t}{sup 2} in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.

  15. Equation of state of wet granular matter

    NASA Astrophysics Data System (ADS)

    Fingerle, A.; Herminghaus, S.

    2008-01-01

    An expression for the near-contact pair correlation function of D -dimensional weakly polydisperse hard spheres is presented, which arises from elementary free-volume arguments. Its derivative at contact agrees very well with our simulations for D=2 . For jammed states, the expression predicts that the number of exact contacts is equal to 2D, in agreement with established simulations. When the particles are wetted, they interact by the formation and rupture of liquid capillary bridges. Since formation and rupture events of capillary bonds are well separated in configuration space, the interaction is hysteretic with a characteristic energy loss Ecb . The pair correlation is strongly affected by this capillary interaction depending on the liquid-bond status of neighboring particles. A theory is derived for the nonequilibrium probability currents of the capillary interaction which determines the pair correlation function near contact. This finally yields an analytic expression for the equation of state, P=P(N/V,T) , of wet granular matter for D=2 , valid in the complete density range from gas to jamming. Driven wet granular matter exhibits a van der Waals-like unstable branch at granular temperatures Tgranular droplets reported for the free cooling of one-dimensional wet granular matter [A. Fingerle and S. Herminghaus, Phys. Rev. Lett. 97, 078001 (2006)], and extends the effect to higher dimensional systems. Since the limiting case of sticky bonds, Ecb≫T , is of relevance for aggregation in general, simulations have been performed which show very good

  16. Mutiscale Modeling of Segregation in Granular Flows

    SciTech Connect

    Sun, Jin

    2007-01-01

    Modeling and simulation of segregation phenomena in granular flows are investigated. Computational models at different scales ranging from particle level (microscale) to continuum level (macroscale) are employed in order to determine the important microscale physics relevant to macroscale modeling. The capability of a multi-fluid model to capture segregation caused by density difference is demonstrated by simulating grain-chaff biomass flows in a laboratory-scale air column and in a combine harvester. The multi-fluid model treats gas and solid phases as interpenetrating continua in an Eulerian frame. This model is further improved by incorporating particle rotation using kinetic theory for rapid granular flow of slightly frictional spheres. A simplified model is implemented without changing the current kinetic theory framework by introducing an effective coefficient of restitution to account for additional energy dissipation due to frictional collisions. The accuracy of predicting segregation rate in a gas-fluidized bed is improved by the implementation. This result indicates that particle rotation is important microscopic physics to be incorporated into the hydrodynamic model. Segregation of a large particle in a dense granular bed of small particles under vertical. vibration is studied using molecular dynamics simulations. Wall friction is identified as a necessary condition for the segregation. Large-scale force networks bearing larger-than-average forces are found with the presence of wall friction. The role of force networks in assisting rising of the large particle is analyzed. Single-point force distribution and two-point spatial force correlation are computed. The results show the heterogeneity of forces and a short-range correlation. The short correlation length implies that even dense granular flows may admit local constitutive relations. A modified minimum spanning tree (MST) algorithm is developed to asymptotically recover the force statistics in the

  17. High energy hadron-hadron collisions. Annual progress report for 1979. [Dept. of Physics, Univ. of Georgia, Athens

    SciTech Connect

    Chou, T.T.

    1980-03-01

    Work on high-energy hadron-hadron collisions in the geometrical model, performed under the DOE Contract No. DE-AS09-76ER00946, is summarized. Specific items studied include the elastic hadron-hadron scattering at ultrahigh energies and the existence of many dips, the computation of meson radii, the hadronic matter current effects on inelastic two-body processes, and the diffraction dissociation processes in hadron-nucleus and hadron-hadron collisions. No data are included with this report; references are given.

  18. Jamming, Yielding, and Rheology of Weakly Vibrated Granular Media

    NASA Astrophysics Data System (ADS)

    Dijksman, Joshua A.; Wortel, Geert H.; van Dellen, Louwrens T. H.; Dauchot, Olivier; van Hecke, Martin

    2011-09-01

    We establish that the rheological curve of dry granular media is nonmonotonic, both in the presence and absence of external mechanical agitations. In the presence of weak vibrations, the nonmonotonic flow curves govern a hysteretic transition between slow but steady and fast, inertial flows. In the absence of vibrations, the nonmonotonic flow curve governs the yielding behavior of granular media. Finally, we show that nonmonotonic flow curves can be seen in at least two different flow geometries and for several granular materials.

  19. Hadronization in the Nuclear Media

    NASA Astrophysics Data System (ADS)

    Elbakyan, G.

    2011-05-01

    The influence of the nuclear environment on the production of charged pions, kaons and (anti)protons in semi-inclusive deep inelastic scattering has been studied by the HERMES experiment at DESY using a 27.6 GeV positron beam. Identified hadron multiplicities have been measured for helium, neon, krypton and xenon relative to that of deuterium as a function of ν, z and {pt2} . Dependences have been extracted in a one and two-dimensional representation, i.e. in the form of detailed binning over one variable and integrating over all other variable or three slices over the other variable. The most prominent feauteres compared to a one-dimensional analysis are changes of the ν-, {pt2} two-dimensional dependences of ratios, in particular in case of protons. In general pions and negative kaons show similar dependences, however, positive kaons, protons and antiprotons behave quite differently.

  20. Beam Collimation at Hadron Colliders

    NASA Astrophysics Data System (ADS)

    Mokhov, N. V.

    2003-12-01

    Operational and accidental beam losses in hadron colliders can have a serious impact on machine and detector performance, resulting in effects ranging from minor to catastrophic. Principles and realization are described for a reliable beam collimation system required to sustain favorable background conditions in the collider detectors, provide quench stability of superconducting magnets, minimize irradiation of accelerator equipment, maintain operational reliability over the life of the machine, and reduce the impact of radiation on personnel and the environment. Based on detailed Monte-Carlo simulations, such a system has been designed and incorporated in the Tevatron collider. Its performance, comparison to measurements and possible ways to further improve the collimation efficiency are described in detail. Specifics of the collimation systems designed for the SSC, LHC, VLHC, and HERA colliders are discussed.

  1. XXth Hadron Collider Physics Symposium

    NASA Astrophysics Data System (ADS)

    In 2009, the Hadron Collider Physics Symposium took place in Evian (France), on the shore of the Geneva Lake, from 16-20 November. It was jointly organised by CERN and the French HEP community (CNRS-IN2P3 and CEA-IRFU). This year's symposium come at an important time for both the Tevatron and LHC communities. It stimulated the completion of analyses for a significant Tevatron data sample, and it allowed an in-depth review of the readiness of the LHC and its detectors just before first collisions. The programme includes sessions on top-quark and electro-weak physics, QCD, B physics, new phenomena, electro-weak symmetry breaking, heavy ions, and the status and commissioning of the LHC machine and its experiments. Conference website : http://hcp2009.in2p3.fr/

  2. Hadronization line in stringy matter

    SciTech Connect

    Biro, Tamas S.; Cleymans, Jean

    2008-09-15

    The equation of state of the string model with linear strings comes close to describing the lattice quantum chromodynamics results and allows for the E/N{approx_equal}6T{sub 0}=1GeV relation found in phenomenological statistical model. The E/N value is derived from the zero pressure condition in quark matter and is a fairly general result. The baryochemical potential dependence of the hadron gas can be met if it is interpreted in the framework of an additive quark model. The conclusion is reached that stringy models explain the E/N=6T{sub 0} relation naturally and independently of the value of the string tension.

  3. Collins Asymmetry at Hadron Colliders

    SciTech Connect

    Yuan, Feng

    2008-01-17

    We study the Collins effect in the azimuthal asymmetricdistribution of hadrons inside a high energy jet in the single transversepolarized proton proton scattering. From the detailed analysis ofone-gluon and two-gluon exchange diagrams contributions, the Collinsfunction is found the same as that in the semi-inclusive deep inelasticscattering and e+e- annihilations. The eikonal propagators in thesediagrams do not contribute to the phase needed for the Collins-typesingle spin asymmetry, and the universality is derived as a result of theWard identity. We argue that this conclusion depends on the momentum flowof the exchanged gluon and the kinematic constraints in the fragmentationprocess, and is generic and model-independent.

  4. Local hadron calibration with ATLAS

    NASA Astrophysics Data System (ADS)

    Giovannini, Paola; ATLAS Liquid Argon Calorimeter Group

    2011-04-01

    The method of Local Hadron Calibration is used in ATLAS as one of the two major calibration schemes for the reconstruction of jets and missing transverse energy. The method starts from noise suppressed clusters and corrects them for non-compensation effects and for losses due to noise threshold and dead material. Jets are reconstructed using the calibrated clusters and are then corrected for out of cone effects. The performance of the corrections applied to the calorimeter clusters is tested with detailed GEANT4 information. Results obtained with this procedure are discussed both for single pion simulations and for di-jet simulations. The calibration scheme is validated on data, by comparing the calibrated cluster energy in data with Mote Carlo simulations. Preliminary results obtained with GeV collision data are presented. The agreement between data and Monte Carlo is within 5% for the final cluster scale.

  5. Nuclear Physics and Hadron Therapy

    SciTech Connect

    Braunn, B.

    2011-12-13

    Hadron therapy uses light charged particles beams (mainly proton and {sup 12}C ions) to irradiate tumors. These beams present a ballistic advantage with a maximum energy deposition at the end of the path. A large dose can be delivered inside a deep tumor while the surrounding healthy tissues are preserved. There is an obvious advantage in using these beams but the beam control has to be achieved and all the physical processes leading to the energy deposition have to be fully under control. This treatment protocol requires accurate control devices and a good knowledge of the physical processes occurring all along the path of the projectile in human tissues. In this report, we will present one example of a beam monitor for the proton therapy. We will also present the experimental program which has been initiated to obtain fundamental data on the nuclear fragmentation process.

  6. Nuclear Physics and Hadron Therapy

    NASA Astrophysics Data System (ADS)

    Braunn, B.; Colin, J.; Courtois, C.; Cussol, D.; Fontbonne, J. M.; Labalme, M.

    2011-12-01

    Hadron therapy uses light charged particles beams (mainly proton and 12C ions) to irradiate tumors. These beams present a ballistic advantage with a maximum energy deposition at the end of the path. A large dose can be delivered inside a deep tumor while the surrounding healthy tissues are preserved. There is an obvious advantage in using these beams but the beam control has to be achieved and all the physical processes leading to the energy deposition have to be fully under control. This treatment protocol requires accurate control devices and a good knowledge of the physical processes occurring all along the path of the projectile in human tissues. In this report, we will present one example of a beam monitor for the proton therapy. We will also present the experimental program which has been initiated to obtain fundamental data on the nuclear fragmentation process.

  7. Hadron cascades produced by electromagnetic cascades

    SciTech Connect

    Nelson, W.R.; Jenkins, T.M.; Ranft, J.

    1986-12-01

    A method for calculating high energy hadron cascades induced by multi-GeV electron and photon beams is described. Using the EGS4 computer program, high energy photons in the EM shower are allowed to interact hadronically according to the vector meson dominance (VMD) model, facilitated by a Monte Carlo version of the dual multistring fragmentation model which is used in the hadron cascade code FLUKA. The results of this calculation compare very favorably with experimental data on hadron production in photon-proton collisions and on the hadron production by electron beams on targets (i.e., yields in secondary particle beam lines). Electron beam induced hadron star density contours are also presented and are compared with those produced by proton beams. This FLUKA-EGS4 coupling technique could find use in the design of secondary beams, in the determination high energy hadron source terms for shielding purposes, and in the estimation of induced radioactivity in targets, collimators and beam dumps.

  8. Constraints on hadronically decaying dark matter

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Tran, David E-mail: alejandro.ibarra@ph.tum.de

    2012-08-01

    We present general constraints on dark matter stability in hadronic decay channels derived from measurements of cosmic-ray antiprotons. We analyze various hadronic decay modes in a model-independent manner by examining the lowest-order decays allowed by gauge and Lorentz invariance for scalar and fermionic dark matter particles and present the corresponding lower bounds on the partial decay lifetimes in those channels. We also investigate the complementarity between hadronic and gamma-ray constraints derived from searches for monochromatic lines in the sky, which can be produced at the quantum level if the dark matter decays into quark-antiquark pairs at leading order.

  9. Hadron scattering and resonances in QCD

    NASA Astrophysics Data System (ADS)

    Dudek, Jozef J.

    2016-05-01

    I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study ππ elastic scattering, including the ρ resonance, as well as coupled-channel π >K, ηK scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  10. Exclusive hadronic and nuclear processes in QCD

    SciTech Connect

    Brodsky, S.J.

    1985-12-01

    Hadronic and nuclear processes are covered, in which all final particles are measured at large invariant masses compared with each other, i.e., large momentum transfer exclusive reactions. Hadronic wave functions in QCD and QCD sum rule constraints on hadron wave functions are discussed. The question of the range of applicability of the factorization formula and perturbation theory for exclusive processes is considered. Some consequences of quark and gluon degrees of freedom in nuclei are discussed which are outside the usual domain of traditional nuclear physics. 44 refs., 7 figs. (LEW)

  11. Rare b Hadron Decays at the LHC

    NASA Astrophysics Data System (ADS)

    Blake, T.; Gershon, T.; Hiller, G.

    2015-10-01

    With the completion of Run I of the CERN Large Hadron Collider, particle physics has entered a new era. The production of unprecedented numbers of heavy-flavored hadrons in high-energy proton-proton collisions allows detailed studies of flavor-changing processes. The increasingly precise measurements allow the Standard Model to be tested with a new level of accuracy. Rare b hadron decays provide some of the most promising approaches for such tests because there are several observables that can be cleanly interpreted from a theoretical viewpoint. In this article, we review the status and prospects in this field, with a focus on precision measurements and null tests.

  12. Adsorption of chlorophenols on granular activated carbon

    SciTech Connect

    Yang, M.

    1993-12-31

    Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

  13. Granular jamming transitions for a robotic mechanism

    NASA Astrophysics Data System (ADS)

    Jiang, Allen; Aste, Tomaso; Dasgupta, Prokar; Althoefer, Kaspar; Nanayakkara, Thrishantha

    2013-06-01

    The jamming transitions for granules growing field of interest in robotics for use in variable stiffness mechanisms. However, the traditional use of air pressure to control the jamming transition requires heavy vacuums, reducing the mobility of the robot. Thus, we propose the use of water as a hydraulic fluid to control the transition between free and clustered granules. This paper presents comparative studies that show that a hydraulic granular jammed finger joint can both achieve the same stiffness level and maintain the same hysteresis level of a pneumatic system, with only a small volume of fluid.

  14. Kinetics of a Frictional Granular Motor

    NASA Astrophysics Data System (ADS)

    Talbot, J.; Wildman, R. D.; Viot, P.

    2011-09-01

    Within the framework of a Boltzmann-Lorentz equation, we analyze the dynamics of a granular rotor immersed in a bath of thermalized particles in the presence of a frictional torque on the axis. In numerical simulations of the equation, we observe two scaling regimes at low and high bath temperatures. In the large friction limit, we obtain the exact solution of a model corresponding to asymptotic behavior of the Boltzmann-Lorentz equation. In the limit of large rotor mass and small friction, we derive a Fokker-Planck equation for which the exact solution is also obtained.

  15. Nonlinear Biot waves in granular media

    NASA Astrophysics Data System (ADS)

    Dazel, Olivier; Tournat, V.

    2010-01-01

    The nonlinear propagation through unconsolidated model granular media is investigated in the frame of the Biot-Allard theory extended to the case of a nonlinear quadratic behavior of the solid frame (the elastic beads and their contacts). We evaluate the importance of mode coupling between solid and fluid waves, depending on the actual fluid and the bead diameter. The application of these results to other media supporting Biot's waves (trabecular bones, porous ceramics, polymer foams...) is straightforward, provided the parameters of the Biot-Allard model are available for these media.

  16. Interstitial gas effect on vibrated granular columns

    NASA Astrophysics Data System (ADS)

    Pastenes, Javier C.; Géminard, Jean-Christophe; Melo, Francisco

    2014-06-01

    Vibrated granular materials have been intensively used to investigate particle segregation, convection, and heaping. We report on the behavior of a column of heavy grains bouncing on an oscillating solid surface. Measurements indicate that, for weak effects of the interstitial gas, the temporal variations of the pressure at the base of the column are satisfactorily described by considering that the column, despite the observed dilation, behaves like a porous solid. In addition, direct observation of the column dynamics shows that the grains of the upper and lower surfaces are in free fall in the gravitational field and that the dilation is due to a small delay between their takeoff times.

  17. Granular convection observed by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Ehrichs, E. E.; Jaeger, H. M.; Karczmar, Greg S.; Knight, James B.; Kuperman, Vadim Yu.; Nagel, Sidney R.

    1995-03-01

    Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here.

  18. Granular convection observed by magnetic resonance imaging

    SciTech Connect

    Ehrichs, E.E.; Jaeger, H.M.; Knight, J.B.; Nagel, S.R.; Karczmar, G.S.; Kuperman, V.Yu.

    1995-03-17

    Vibrations in a granular material can spontaneously produce convection rolls reminiscent of those seen in fluids. Magnetic resonance imaging provides a sensitive and noninvasive probe for the detection of these convection currents, which have otherwise been difficult to observe. A magnetic resonance imaging study of convection in a column of poppy seeds yielded data about the detailed shape of the convection rolls and the depth dependence of the convection velocity. The velocity was found to decrease exponentially with depth; a simple model for this behavior is presented here. 31 refs., 4 figs.

  19. Fluctuation spectroscopy of granularity in superconducting structures.

    SciTech Connect

    Lerner, I. V.; Varlamov, A. A.; Vinokur, V. M.; Materials Science Division; Univ. of Birmingham; Viale del Politecnico

    2008-03-01

    We suggest to use 'fluctuation spectroscopy' as a method to detect granularity in a disordered metal close to a superconducting transition. We show that with lowering temperature T the resistance R(T) of a system of relatively large grains initially grows due to the fluctuation suppression of the one-electron tunneling but decreases with further lowering T due to the coherent charge transfer of the fluctuation Cooper pairs. Under certain conditions, such a maximum in R(T) turns out to be sensitive to weak magnetic fields due to a novel Maki-Thompson-type mechanism.

  20. Gravity-driven dense granular flows

    SciTech Connect

    ERTAS,DENIZ; GREST,GARY S.; HALSEY,THOMAS C.; DEVINE,DOV; SILBERT,LEONARDO E.

    2000-03-29

    The authors report and analyze the results of numerical studies of dense granular flows in two and three dimensions, using both linear damped springs and Hertzian force laws between particles. Chute flow generically produces a constant density profile that satisfies scaling relations suggestive of a Bagnold grain inertia regime. The type for force law has little impact on the behavior of the system. Failure is not initiated at the surface, consistent with the absence of surface flows and different principal stress directions at vs. below the surface.

  1. Biological and robotic movement through granular media

    NASA Astrophysics Data System (ADS)

    Goldman, Daniel

    2008-03-01

    We discuss laboratory experiments and numerical simulations of locomotion of biological organisms and robots on and within a granular medium. Terrestrial locomotion on granular media (like desert and beach sand) is unlike locomotion on rigid ground because during a step the material begins as a solid, becomes a fluid and then re-solidifies. Subsurface locomotion within granular media is unlike swimming in water for similar reasons. The fluidization and solidification depend on the packing properties of the material and can affect limb penetration depth and propulsive force. Unlike aerial and aquatic locomotion in which the Navier-Stokes equations can be used to model environment interaction, models for limb interaction with granular media do not yet exist. To study how the fluidizing properties affect speed in rapidly running and swimming lizards and crabs, we use a trackway composed of a fluidized bed of of 250 μm glass spheres. Pulses of air to the bed set the solid volume fraction 0.59<φ<0.63; a constant flow rate Q below the onset of fluidization (at Q=Qf) linearly reduces the material strength (resistance force per depth) at fixed φ for increasing Q. Systematic studies of four species of lizard and a species of crab (masses 20 grams) reveal that as Q increases, the average running speed of an animal decreases proportionally to √M/A-const(1-Q/Qf) where M is the mass of the animal and A is a characteristic foot area. While the crabs decrease speed by nearly 75 % as the material weakens to a fluid, the zebra tailed lizard uses long toes and a plantigrade foot posture at foot impact to maintain high speed ( 1.5 m/sec). We compare our biological results to systematic studies of a physical model of an organism, a 2 kg hexapedal robot SandBot. We find that the robot speed sensitively depends on φ and the details of the limb trajectory. We simulate the robot locomotion by computing ground reaction forces on a numerical model of the robot using a soft

  2. Granular cell tumor of the esophagus.

    PubMed

    Patel, R M; DeSota-LaPaix, F; Sika, J V; Mallaiah, L R; Purow, E

    1981-12-01

    Two cases of granular cell tumor of the esophagus are reported and the main features of the previously reported cases are summarized. Dysphagia and substernal discomfort or pain are the most common symptoms seen and are likely to occur with lesions greater than 1 cm. in diameter. The diagnosis should be considered in adult females with an intramural mass of the esophagus. The cell of origin is still disputed. The treatment of choice, when the patient is symptomatic or the lesion greater than 1 cm. in size, is local resection. The tumor, when incidentally discovered in an asymptomatic patient, may safely be followed endoscopically. PMID:6277183

  3. Dynamics of the breakdown of granular clusters

    NASA Astrophysics Data System (ADS)

    Coppex, François; Droz, Michel; Lipowski, Adam

    2002-07-01

    Recently van der Meer et al. studied the breakdown of a granular cluster [Phys. Rev. Lett. 88, 174302 (2002)]. We reexamine this problem using an urn model, which takes into account fluctuations and finite-size effects. General arguments are given for the absence of a continuous transition when the number of urns (compartments) is greater than two. Monte Carlo simulations show that the lifetime of a cluster τ diverges at the limits of stability as τ~N1/3, where N is the number of balls. After the breakdown, depending on the dynamical rules of our urn model, either normal or anomalous diffusion of the cluster takes place.

  4. Granular size segregation in underwater sand ripples.

    PubMed

    Rousseaux, G; Caps, H; Wesfreid, J-E

    2004-02-01

    We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly depend on the sand bed preparation. The initial wavelength of the mixture is measured. In the final steady state, a segregation in volume is observed instead of a segregation at the surface as reported before. The correlation between this phenomenon and the fluid flow is emphasised. Finally, different "exotic" patterns and their geophysical implications are presented. PMID:15052430

  5. Exploring Granular Flows at Intermediate Velocities

    NASA Astrophysics Data System (ADS)

    Brodsky, E. E.; van der Elst, N.

    2012-12-01

    Geophysical and geomorphological flows often encompass a wide range of strain rates. Landslides accelerate from nearly static conditions to velocities in the range of meters/seconds. The rheology of granular flows for the end-members is moderately well-understood, but the constitutive low at intermediate velocities is largely unexplored. Here we present evidence that granular flows transition through a regime in which internally generated acoustic waves play a critical role in controlling rheology. In laboratory experiments on natural sand under shear in a commercial rheometer, we observe that the steady-state flows at intermediate velocities are compacted relative to the end members. In a confined volume, this compaction results in a decrease in stress on the boundaries. We establish the key role of the acoustic waves by measuring the noise generated by the shear flows with an accelerometer and then exciting the flow with similar amplitude noise under lower shear rate conditions. The observed compaction for a given amplitude noise is the same in both cases, regardless of whether the noise is generated internally by the grains colliding or artificially applied externally. The boundaries of this acoustically controlled regime can be successfully predicted through non-dimensional analysis balancing the overburden, acoustic pressure and granular inertial terms. In our laboratory experiments, this regime corresponds to 0.1 to 10 cm/s. The controlling role of acoustic waves in intermediate velocities is significant because: (1) Geological systems must pass through this regime on their route to instability. (2) Acoustic waves are much more efficiently generated by angular particles, likely to be found in natural samples, than by perfectly spherical particles, which are more tractable for laboratory and theoretical studies. Therefore, this regime is likely to be missed in many analog and computational approaches. (3) Different mineralogies and shapes result in different

  6. Large corrections to high-pT hadron-hadron scattering in QCD

    SciTech Connect

    Ellis, R. K.; Furman, M. A.; Haber, H. E.; Hinchliffe, I.

    1980-10-01

    We have eomputed the first non-trivial QCD corrections to the quark-quark scattering process which contributes to the production of hadrons at large p{sub T} in hadron-hadron collisions. Using quark distribution functions defined in deep inelastic scattering and fragmentation functions defined in one particle inclusive e{sup +}e{sup -} annihilation, we find that the corrections are large. This implies that QCD perturbation theory may not be reliable for large p{sub T} hadron physics.

  7. Hadron spectroscopy and B physics at RHIC

    SciTech Connect

    Chung, S.U.; Weygand, D.P.; Willutzki, H.J.

    1991-11-01

    A description is given of the physics opportunities at RHIC regarding quark-gluon spectroscopy. The basic idea is to isolate with appropriate triggers the sub-processes pomeron + pomeron {yields} hadrons and {gamma}{sup *} + {gamma}{sup *} {yields} hadrons with the net effective mass of hadrons in the range of 1.0 to 10.0 GeV, in order to study the hadronic states composed of quarks and gluons. The double-pomeron interactions are expected to produce glueballs and hybrids preferentially, while the two-offshell-photon initial states should couple predominantly to quarkonia and multiquark states. Of particular interest is the possibility of carrying out a CP-violation study in the self-tagging B decays, B{sub d}{sup 0} {yields} K{sup +}{pi}{sup {minus}} and {bar B}{sub d}{sup 0} {yields} K{sup {minus}}{pi}{sup +}. 20 refs., 4 figs.

  8. Hadronic and nuclear phenomena in quantum chromodynamics

    SciTech Connect

    Brodsky, S.J.

    1987-06-01

    Many of the key issues in understanding quantum chromodynamics involves processes at intermediate energies. We discuss a range of hadronic and nuclear phenomena - exclusive processes, color transparency, hidden color degrees of freedom in nuclei, reduced nuclear amplitudes, jet coalescence, formation zone effects, hadron helicity selection rules, spin correlations, higher twist effects, and nuclear diffraction - as tools for probing hadron structure and the propagation of quark and gluon jets in nuclei. Many of these processes can be studied in electroproduction, utilizing internal targets in storage rings. We also review several areas where there has been significant theoretical progress in determining the form of hadron and nuclear wavefunctions, including QCD sum rules, lattice gauge theory, and discretized light-cone quantization. 98 refs., 40 figs., 2 tabs.

  9. The CMS central hadron calorimeter: Update

    SciTech Connect

    Freeman, J.

    1998-06-01

    The CMS central hadron calorimeter is a brass absorber/ scintillator sampling structure. We describe details of the mechanical and optical structure. We also discuss calibration techniques, and finally the anticipated construction schedule.

  10. Physical Properties of Various Materials Relevant to Granular Flow

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of the ubiquitous nature of granular materials, ranging from natural avalanches to industrial storage and processing operations, interest in quantifying and predicting the dynamics of granular flow continues to increase. The objective of this study was to investigate various physical proper...

  11. BACKWASH OF GRANULAR FILTERS USED IN WASTEWATER FILTRATION

    EPA Science Inventory

    The use of deep granular filters in waste treatment is of growing importance. The key to long-term operating success of such filters is proper bed design and adequate bed cleaning during backwashing. Cleaning granular filters by water backwash alone to fluidize the filter bed is ...

  12. Intraorbital Granular Cell Tumor Ophthalmologic and Radiologic Findings

    PubMed Central

    de la Vega, Gabriela; Villegas, Victor M; Velazquez, Jose; Barrios, Mirelys; Murray, Timothy G; Elhammady, Mohamed Samy

    2015-01-01

    Granular cell tumor is a rare soft tissue neoplasm that commonly affects the head and neck regions. We describe a case of a granular cell tumor of the orbit including its clinical presentation, histopathology, and magnetic resonance imaging findings. PMID:25963156

  13. 75 FR 67105 - Granular Polytetrafluoroethylene Resin From Italy and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-01

    ... granular polytetrafluoroethylene resin from Japan (53 FR 32267). On August 30, 1988, Commerce issued an... from Italy and Japan (65 FR 6147, February 8, 2000). Following second five-year reviews by Commerce and... orders on imports of granular polytetrafluoroethylene resin from Italy and Japan (70 FR 76026)....

  14. USE OF GRANULAR GRAPHITE FOR ELECTROLYTIC DECHLORINATION OF TRICHLOROETHYLENE

    EPA Science Inventory

    Granular graphite is a potential electrode material for the electrochemical remediation of refractory chlorinated organic compounds such as trichloroethylene (TCE). However, the use of granular graphite can complicate the experimental results. On one hand, up to 99% of TCE was re...

  15. Effects of granular charge on flow and mixing

    NASA Astrophysics Data System (ADS)

    Shinbrot, T.; Herrmann, H. J.

    2008-12-01

    Sandstorms in the desert have long been reported to produce sparks and other electrical disturbances - indeed as long ago as 1850, Faraday commented on the peculiarities of granular charging during desert sandstorms. Similarly, lightning strikes within volcanic dust plumes have been repeatedly reported for over half a century, but remain unexplained. The problem of granular charging has applied, as well as natural, implications, for charged particle clouds frequently generate spectacularly devastating dust explosions in granular processing plants, and sand becomes strongly electrified by helicopters traveling in desert environments. The issue even has implications for missions to the Moon and to Mars, where charged dust degrades solar cells viability and clings to spacesuits, limiting the lifetime of their joints. Despite the wide-ranging importance of granular charging, even the simplest aspects of its causes remain elusive. To take one example, sand grains in the desert manage to charge one another despite having only similar materials to rub against over expanses of many miles - thus existing theories of charging due to material differences fail entirely to account for the observed charging of desert sands. In this talk, we describe recent progress made in identifying underlying causes of granular charging, both in desert-like environments and in industrial applications, and we examine effects of granular charging on flow, mixing and separation of common granular materials. We find that charging of identical grains can occur under simple laboratory conditions, and we make new predictions for the effects of this charging on granular behaviours.

  16. Scaling of liquid-drop impact craters in granular media

    NASA Astrophysics Data System (ADS)

    Zhao, Runchen; Zhang, Qianyun; Tjugito, Hendro; Gao, Ming; Cheng, Xiang

    Granular impact cratering by liquid drops is a ubiquitous phenomenon, directly relevant to many important natural and industrial processes such as soil erosion, drip irrigation, and dispersion of micro-organisms in soil. Here, by combining the high-speed photography with high precision laser profilometry, we investigate the liquid-drop impact dynamics on granular surfaces and monitor the morphology of resulting craters. Our experiments reveal novel scaling relations between the size of granular impact craters and important control parameters including the impact energy, the size of impinging drops and the degree of liquid saturation in a granular bed. Interestingly, we find that the scaling for liquid-drop impact cratering in dry granular media can be quantitatively described by the Schmidt-Holsapple scaling originally proposed for asteroid impact cratering. On the other hand, the scaling for impact craters in wet granular media can be understood by balancing the inertia of impinging drops and the strength of impacted surface. Our study sheds light on the mechanism governing liquid-drop impacts on dry/wet granular surfaces and reveals a remarkable analogy between familiar phenomena of raining and catastrophic asteroid strikes. Scaling of liquid-drop impact craters in granular media.

  17. Construction of a technological semi-digital hadronic calorimeter using GRPC

    NASA Astrophysics Data System (ADS)

    Laktineh, I.

    2011-04-01

    A high-granularity semi-digital Hadronic calorimeter using GRPC as sensitive medium is one of the two HCAL options considered by the ILD collaboration to be proposed for the detector of the future International Linear Collider project. A prototype of 1m3 has been conceived within the CALICE collaboration in order to validate this option. The prototype intends to be as close as possible to the one proposed in the ILD Letter Of Intent. Few units made of 1m2 GRPC fully equipped with semi-digital readout electronics and new gas distribution design were produced and successfully tested. In 2010 we intend to produce 40 similar units to be inserted in a self-supporting mechanical structure. The prototype will then be exposed to TestBeams at CERN for final validation.

  18. COMPASS Hadron Multiplicity Measurements and Fragmentation Functions

    NASA Astrophysics Data System (ADS)

    Stolarski, M.

    2016-03-01

    COMPASS preliminary results on hadron, pion and kaon multiplicities are presented. The hadron and pion data show a good agreement with (N)LO QCD expectations and some of these preliminary data have been already successfully incorporated in the global NLO QCD fits to world data. However, the results for kaon multiplicities, are different from the expectations of the DSS fit. There is also a tension between COMPASS and HERMES results, the only other experiment which measured kaon multiplicities in SIDIS.

  19. Hadron spectrum with staggered dynamical quarks

    SciTech Connect

    Bitar, K.M.; Kennedy, A.D.; Liu, Weiqiang . Supercomputer Computations Research Inst.); DeGrand, T.A. . Dept. of Physics); Gottlieb, S. ); Kogut, J.B.; Renken, R.L. . Dept. of Physics); Ogilvie, M.C. . Dept. of Physic

    1989-01-01

    We describe a recent calculation of the hadron spectrum with two flavors of staggered dynamical quarks with a gauge coupling 6/g{sup 2} = 5.60 and quark masses of 0.025 and 0.01. The gauge fields were generated using the hybrid algorithm on a 12{sup 4} lattice that was doubled or quadrupoled to calculate hadron propagators. 5 refs., 5 figs.

  20. Experimental insight into b-hadron lifetimes

    NASA Astrophysics Data System (ADS)

    Fernández, J. P.; Flores-Castillo, L. R.

    2016-01-01

    A review on the experimental status of the measurement of b-hadron lifetimes is presented. After a brief introduction to the Standard Model, the work done by theorists about b-hadron lifetimes is put in context. The core of the review is devoted to explain the ingredients that are necessary to make a lifetime measurement, from the detector infrastructure and requirements to the statistical treatment of the data. Finally, an overview of current experimental results and future prospects is presented.

  1. Heavy flavor physics at hadron colliders

    SciTech Connect

    Barbaro-Galtieri, A.

    1991-12-01

    The search for the top quark has dominated heavy flavor physics at hadron colliders. For Standard model decay of top the present mass limit in m{sub t} > 89 GeV (95% C.L.). Bottom production cross sections are quite large at hadron colliders, thus providing enough statistics for extensive studies. Results on cross sections, B{sup 0} {minus} {bar B}{sup 0} mixing, exclusive channels and rare B decays will be summarized.

  2. Hadrons in AdS/QCD correspondence

    SciTech Connect

    Vega, Alfredo; Schmidt, Ivan

    2009-03-01

    We present a holographical soft wall model that is able to reproduce not only Regge spectra for hadrons with arbitrary integer spin, but also with spin 1/2 and 3/2, and with an arbitrary number of constituents. The model includes the anomalous dimension of operators that create hadrons, together with a dilaton, whose form is suggested by Einstein equations and the AdS metric used.

  3. Hadron thermodynamics in relativistic nuclear collisions

    NASA Technical Reports Server (NTRS)

    Ammiraju, P.

    1985-01-01

    Various phenomenological models based on statistical thermodynamical considerations were used to fit the experimental data at high P sub T to a two temperature distribution. Whether this implies that the two temperatures belong to two different reaction mechanisms, or consequences of Lorentz-contraction factor, or related in a fundamental way to the intrinsic thermodynamics of Space-Time can only be revealed by further theoretical and experimental investigations of high P sub T phenomena in extremely energetic hadron-hadron collisions.

  4. Modelling hadronic interactions in HEP MC generators

    NASA Astrophysics Data System (ADS)

    Skands, Peter

    2015-08-01

    HEP event generators aim to describe high-energy collisions in full exclusive detail. They combine perturbative matrix elements and parton showers with dynamical models of less well-understood phenomena such as hadronization, diffraction, and the so-called underlying event. We briefly summarise some of the main concepts relevant to the modelling of soft/inclusive hadron interactions in MC generators, in particular PYTHIA, with emphasis on questions recently highlighted by LHC data.

  5. Signals for vector leptoquarks in hadronic collisions

    SciTech Connect

    Cieza Montalvo, J.E.; Eboli, O.J.P. )

    1994-07-01

    We analyze systematically the signatures of vector leptoquarks in hadronic collisions. We examine their single and pair productions, as well as their effects on the production of lepton pairs. Our results indicate that a machine like the CERN Large Hadron Collider (LHC) will be able to unravel the existence of vector leptoquarks with masses up to the range of 2--3 TeV.

  6. Hadron spectroscopy from strangeness to charm and beauty

    NASA Astrophysics Data System (ADS)

    Zou, B. S.

    2013-09-01

    Quarks of different flavors have different masses, which will cause breaking of flavor symmetries of QCD. Flavor symmetries and their breaking in hadron spectroscopy play important role for understanding the internal structures of hadrons. Hadron spectroscopy with strangeness reveals the importance of unquenched quark dynamics. Systematic study of hadron spectroscopy with strange, charm and beauty quarks would be very revealing and essential for understanding the internal structure of hadrons and its underlying quark dynamics.

  7. Theoretical Equations of State for Porous/Granular Materials

    NASA Astrophysics Data System (ADS)

    Boettger, Jonathan

    2013-06-01

    Although the equation of state (EOS) for a porous/granular material is identical to the EOS for the equivalent non-porous material, the requirement that the EOS must provide a realistic model of the material in its porous/granular state adds additional challenges for EOS modelers. These difficulties can be divided into two broad categories. First, dynamic processes often drive porous/granular materials through regions of thermodynamic phase space that are poorly described by standard wide-ranging tabular EOS. Second, for materials that are only available in a granular form, it can be difficult to accurately measure the material properties/parameters that are routinely used to constrain a theoretical EOS. This talk will attempt to describe in some detail the many challenges posed to EOS modelers by porous/granular materials. Work supported by the U.S. Dept. of Energy under contract DE-AC52-06NA25396.

  8. Self-burrowing seeds: drag reduction in granular media

    NASA Astrophysics Data System (ADS)

    Jung, Wonjong; Choi, Sung Mok; Kim, Wonjung; Kim, Ho-Young

    2014-11-01

    We present the results of a combined experimental and theoretical investigation of drag reduction of self-burrowing seeds in granular media. In response to environmental changes in humidity, the awn (a tail-like appendage of seed) of Pelargonium carnosum exhibits coiling-uncoiling deformation which induces the thrust and rotary motions of the head of the seed against the surface of the soil. Using various sizes of glass beads that mimic the granular soil, we measure the thrust forces required for the seed of Pelargonium carnosum to penetrate into granular media with and without rotation. Our quantitative measurements show that the rotation of the seed remarkably reduces the granular drag as compared to the drag against the non-spinning seed. This leads us to conclude that the hygroscopically active awns of Pelargonium carnosum enables its seed to dig into the relatively coarse granular soils.

  9. Segregation time-scales in model granular flows

    NASA Astrophysics Data System (ADS)

    Staron, Lydie; Phillips, Jeremy C.

    2016-04-01

    Segregation patterns in natural granular systems offer a singular picture of the systems evolution. In many cases, understanding segregation dynamics may help understanding the system's history as well as its future evolution. Among the key questions, one concerns the typical time-scales at which segregation occurs. In this contribution, we present model granular flows simulated by means of the discrete Contact Dynamics method. The granular flows are bi-disperse, namely exhibiting two grain sizes. The flow composition and its dynamics are systematically varied, and the segregation dynamics carefully analyzed. We propose a physical model for the segregation that gives account of the observed dependence of segregation time scales on composition and dynamics. References L. Staron and J. C. Phillips, Stress partition and micro-structure in size-segregating granular flows, Phys. Rev. E 92 022210 (2015) L. Staron and J. C. Phillips, Segregation time-scales in bi-disperse granular flows, Phys. Fluids 26 (3), 033302 (2014)

  10. Observation of charmless hadronic B decays

    NASA Astrophysics Data System (ADS)

    Buskulic, D.; de Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Odier, P.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Orteu, S.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Girone, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Alemany, R.; Bazarko, A. O.; Bonvicini, G.; Bright-Thomas, P.; Cattaneo, M.; Comas, P.; Coyle, P.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Lutters, G.; Martin, E. B.; Mato, P.; Minten, A.; Miquel, R.; Mir, Ll. M.; Moneta, L.; Oest, T.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rensing, P.; Rizzo, G.; Rolandi, L.; Schlatter, D.; Schmelling, M.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Venturi, A.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. B.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Focardi, E.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, F.; Thorn, S.; Turnbull, R. M.; Becker, U.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Schmidt, M.; Sommer, J.; Stenzel, H.; Tittel, K.; Werner, S.; Wunsch, M.; Abbaneo, D.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Stacey, A. M.; Williams, M. D.; Dissertori, G.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Sloan, T.; Williams, M. I.; Galla, A.; Giehl, I.; Greene, A. M.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Calvet, D.; Carr, J.; Diaconu, C.; Etienne, F.; Konstantinidis, N.; Payre, P.; Rousseau, D.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Ragusa, F.; Bauer, C.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Dydak, F.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; Denis, R. St.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Choi, Y.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Park, H. J.; Schune, M.-H.; Simion, S.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Ciulli, V.; Dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Vannini, C.; Verdini, P. G.; Walsh, J.; Blair, G. A.; Bryant, L. M.; Cerutti, F.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Koksal, A.; Letho, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Minguet-Rodriguez, J.; Rivera, F.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Rothberg, J.; Wasserbaech, S.; Armstrong, S. R.; Elmer, P.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; González, S.; Grahl, J.; Greening, T. C.; Hayes, O. J.; Hu, H.; McNamara, P. A.; Nachtman, J. M.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, A. M.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zheng, M.; Zobernig, G.; Aleph Collaboration

    1996-02-01

    Four candidates for charmless hadronic B decay are observed in a data sample of four million hadronic Z decays recorded by the ALEPH detector at LEP. The probability that these events come from background sources is estimated to be less than 10 -6. The average branching ratio of weakly decaying B hadrons (a mixture of B d0, B s0 and Λb weighted by their production cross sections and lifetimes, here denoted B) into two long-lived charged hadrons (pions, kaons or protons) is measured to be Br(B → h +h -) = (1.7 -0.7+1.0 ± 0.2) × 10 -5. The relative branching fraction {Br( B d(s)0 → π +π -(K -)) }/{Br( B d(s)0 → h +h -) } is measured to be 1.0 -0.3 -0.1+0.0 +0.0. In addition, branching ratio upper limits are obtained for a variety of exclusive charmless hadronic two-body decays of B hadrons.

  11. Light-cone quantization and hadron structure

    SciTech Connect

    Brodsky, S.J.

    1996-04-01

    Quantum chromodynamics provides a fundamental description of hadronic and nuclear structure and dynamics in terms of elementary quark and gluon degrees of freedom. In practice, the direct application of QCD to reactions involving the structure of hadrons is extremely complex because of the interplay of nonperturbative effects such as color confinement and multi-quark coherence. In this talk, the author will discuss light-cone quantization and the light-cone Fock expansion as a tractable and consistent representation of relativistic many-body systems and bound states in quantum field theory. The Fock state representation in QCD includes all quantum fluctuations of the hadron wavefunction, including fax off-shell configurations such as intrinsic strangeness and charm and, in the case of nuclei, hidden color. The Fock state components of the hadron with small transverse size, which dominate hard exclusive reactions, have small color dipole moments and thus diminished hadronic interactions. Thus QCD predicts minimal absorptive corrections, i.e., color transparency for quasi-elastic exclusive reactions in nuclear targets at large momentum transfer. In other applications, such as the calculation of the axial, magnetic, and quadrupole moments of light nuclei, the QCD relativistic Fock state description provides new insights which go well beyond the usual assumptions of traditional hadronic and nuclear physics.

  12. Nonlocal modeling of granular flows down inclines.

    PubMed

    Kamrin, Ken; Henann, David L

    2015-01-01

    Flows of granular media down a rough inclined plane demonstrate a number of nonlocal phenomena. We apply the recently proposed nonlocal granular fluidity model to this geometry and find that the model captures many of these effects. Utilizing the model's dynamical form, we obtain a formula for the critical stopping height of a layer of grains on an inclined surface. Using an existing parameter calibration for glass beads, the theoretical result compares quantitatively to existing experimental data for glass beads. This provides a stringent test of the model, whose previous validations focused on driven steady-flow problems. For layers thicker than the stopping height, the theoretical flow profiles display a thickness-dependent shape whose features are in agreement with previous discrete particle simulations. We also address the issue of the Froude number of the flows, which has been shown experimentally to collapse as a function of the ratio of layer thickness to stopping height. While the collapse is not obvious, two explanations emerge leading to a revisiting of the history of inertial rheology, which the nonlocal model references for its homogeneous flow response. PMID:25376561

  13. A new rheology for dense granular flows

    NASA Astrophysics Data System (ADS)

    Jop, Pierre

    2005-11-01

    Recent experiments and numerical simulations of dry and dense granular flows suggest that a simple rheological description, in terms of a shear rate dependent friction coefficient, may be sufficient to capture the major flow properties [1,2]. In this work we generalize this approach by proposing a tensorial form of this rheology leading to 3D hydrodynamic equations for granular flows. We show that quantitative predictions can be obtained with this model by studying the flow of grains on a pile confined between two lateral walls. In this configuration we have experimentally measured the free surface velocity profile, the flowing thickness for different flow rates and channel widths. The results are compared with numerical simulations of the hydrodynamic model and quantitative agreement is observed. This study strongly supports the relevance of the proposed rheology. 1. F. da Cruz, S. Emam, M. Prochnow, J.-N. Roux and F. Chevoir, cond-mat/ 0503682 (2005)2. G.D.R. Midi, EPJE14 367-371 (2004)

  14. Drop floating on a granular raft

    NASA Astrophysics Data System (ADS)

    Jambon-Puillet, Etienne; Josserand, Christophe; Protiere, Suzie

    2015-11-01

    When a droplet comes in contact with a bath of the same liquid, it coalesces to minimize the surface energy. This phenomenon reduces emulsion stability and is usually fought with surfactant molecules. Another way to slow down coalescence is to use colloidal solid particles. In this case the particles spontaneously migrate to the interface to form ``Pickering'' emulsions and act as a barrier between droplets. Here we use dense, large particles (~ 500 μm) which form a monolayer at an oil/water interface that we call a granular raft. When a droplet is placed on top of such a raft, for a given set of particle properties (contact angle/size), the raft prevents coalescence indefinitely. However, in contrast to what happens when a droplet is placed on a hydrophobic surface and never wets the surface, here the droplet is strongly anchored to the raft and deforms it. We will use this specific configuration to probe the mechanical response of the granular raft: by controlling the droplet volume we can impose tensile or compressive stresses. Finally we will show that the drop, spherical at first, slowly takes a more complex shape as it's volume increases. This shape is not reversible as the drop volume is decreased. The drop can become oblate or prolate with wrinkling of the raft.

  15. Pressure-shear experiments on granular materials.

    SciTech Connect

    Reinhart, William Dodd; Thornhill, Tom Finley, III; Vogler, Tracy John; Alexander, C. Scott

    2011-10-01

    Pressure-shear experiments were performed on granular tungsten carbide and sand using a newly-refurbished slotted barrel gun. The sample is a thin layer of the granular material sandwiched between driver and anvil plates that remain elastic. Because of the obliquity, impact generates both a longitudinal wave, which compresses the sample, and a shear wave that probes the strength of the sample. Laser velocity interferometry is employed to measure the velocity history of the free surface of the anvil. Since the driver and anvil remain elastic, analysis of the results is, in principal, straightforward. Experiments were performed at pressures up to nearly 2 GPa using titanium plates and at higher pressure using zirconium plates. Those done with the titanium plates produced values of shear stress of 0.1-0.2 GPa, with the value increasing with pressure. On the other hand, those experiments conducted with zirconia anvils display results that may be related to slipping at an interface and shear stresses mostly at 0.1 GPa or less. Recovered samples display much greater particle fracture than is observed in planar loading, suggesting that shearing is a very effective mechanism for comminution of the grains.

  16. Linear response and hydrodynamics for granular fluids.

    PubMed

    Dufty, James; Baskaran, Aparna; Brey, J Javier

    2008-03-01

    A formal derivation of linear hydrodynamics for a granular fluid is given. The linear response to small spatial perturbations of a homogeneous reference state is studied in detail, using methods of nonequilibrium statistical mechanics. A transport matrix for macroscopic excitations in the fluid is defined in terms of the response functions. An expansion in the wave vector to second order allows identification of all phenomenological susceptibilities and transport coefficients through Navier-Stokes order in terms of appropriate time correlation functions. The transport coefficients in this representation are the generalization to granular fluids of the familiar Helfand and Green-Kubo relations for normal fluids. The analysis applies to a variety of collision rules. Important differences in both the analysis and results from those for normal fluids are identified and discussed. A scaling limit is described corresponding to the conditions under which idealized inelastic hard sphere models can apply. Further details and interpretation are provided in the paper following this one, by specialization to the case of smooth, inelastic hard spheres with constant coefficient of restitution. PMID:18517373

  17. Expression for the granular elastic energy.

    PubMed

    Jiang, Yimin; Zheng, Hepeng; Peng, Zheng; Fu, Liping; Song, Shixiong; Sun, Qicheng; Mayer, Michael; Liu, Mario

    2012-05-01

    Granular solid hydrodynamics (GSH) is a broad-ranged continual mechanical description of granular media capable of accounting for static stress distributions, yield phenomena, propagation and damping of elastic waves, the critical state, shear band, and fast dense flow. An important input of GSH is an expression for the elastic energy needed to deform the grains. The original expression, though useful and simple, has some drawbacks. Therefore a slightly more complicated expression is proposed here that eliminates three of them: (1) The maximal angle at which an inclined layer of grains remains stable is increased from 26^{∘} to the more realistic value of 30^{∘}. (2) Depending on direction and polarization, transverse elastic waves are known to propagate at slightly different velocities. The old expression neglects these differences, the new one successfully reproduces them. (3) Most importantly, the old expression contains only the Drucker-Prager yield surface. The new one contains in addition those named after Coulomb, Lade-Duncan, and Matsuoka-Nakai-realizing each, and interpolating between them, by shifting a single scalar parameter. PMID:23004747

  18. Three-phase fracturing in granular material

    NASA Astrophysics Data System (ADS)

    Campbell, James; Sandnes, Bjornar

    2015-04-01

    There exist numerous geo-engineering scenarios involving the invasion of a gas into a water-saturated porous medium: in fracking, this may occur during the fracking process itself or during subsequent gas penetration into propant beds; the process is also at the heart of carbon dioxide sequestration. We use a bed of water-saturated glass beads confined within a Hele-Shaw cell as a model system to illuminate these processes. Depending on packing density, injection rate and other factors, air injected into this system may invade in a broad variety of patterns, including viscous fingering, capillary invasion, bubble formation and fracturing. Here we focus primarily on the latter case. Fracturing is observed when air is injected into a loosely packed bed of unconsolidated granular material. Our approach allows us to image the complete fracture pattern as it forms, and as such to study both the topographical properties of the resulting pattern (fracture density, braching frequency etc) and the dynamics of its growth. We present an overview of the fracturing phenomenon within the context of pattern formation in granular fluids as a whole. We discuss how fracturing arises from an interplay between frictional, capillary and viscous forces, and demonstrate the influence of various parameters on the result.

  19. Rainwater Channelization and Infiltration in Granular Media

    NASA Astrophysics Data System (ADS)

    Cejas, Cesare; Wei, Yuli; Barrois, Remi; Durian, Douglas; Dreyfus, Remi; Compass Team

    2013-03-01

    We investigate the formation of fingered flow in dry granular media under simulated rainfall using a quasi-2D experimental set-up composed of a random close packing of mono-disperse glass beads. We determine effects of grain diameter and surface wetting properties on the formation and infiltration of water channels. For hydrophilic granular media, rainwater initially infiltrates a shallow top layer of soil creating a uniform horizontal wetting front before instabilities occur and grow to form water channels. For hydrophobic media, rainwater ponds on the soil surface rather than infiltrates and water channels may still occur at a later time when the hydraulic pressure of the ponding water exceeds the capillary repellency of the soil. We probe the kinetics of the fingering instabilities that serve as precursors for the growth and drainage of water channels. We also examine the effects of several different methods on improving rainwater channelization such as varying the level of pre-saturation, modifying the soil surface flatness, and adding superabsorbent hydrogel particles.

  20. Mechanics of Granular Materials (MGM) Investigators

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Key persornel in the Mechanics of Granular Materials (MGM) experiment at the University of Colorado at Boulder include Tawnya Ferbiak (software engineer), Susan Batiste (research assistant), and Christina Winkler (graduate research assistant). Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. MGM experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that cannot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: University of Colorado at Boulder).

  1. Mechanics of Granular Materials labeled hardware

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Mechanics of Granular Materials (MGM) flight hardware takes two twin double locker assemblies in the Space Shuttle middeck or the Spacehab module. Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. MGM experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that carnot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: NASA/MSFC).

  2. Machanics of Granular Materials (MGM) Investigator

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Key persornel in the Mechanics of Granular Materials (MGM) experiment include Khalid Alshibli, project scientist at NASA's Marshall Space Flight Center (MSFC). Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. MGM experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that cannot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: MSFC).

  3. Mechanic of Granular Materials (MGM) Investigator

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Key persornel in the Mechanics of Granular Materials (MGM) experiment are Mark Lankton (Program Manager at University Colorado at Boulder), Susan Batiste (research assistance, UCB), and Stein Sture (principal investigator). Sand and soil grains have faces that can cause friction as they roll and slide against each other, or even cause sticking and form small voids between grains. This complex behavior can cause soil to behave like a liquid under certain conditions such as earthquakes or when powders are handled in industrial processes. MGM experiments aboard the Space Shuttle use the microgravity of space to simulate this behavior under conditions that cannot be achieved in laboratory tests on Earth. MGM is shedding light on the behavior of fine-grain materials under low effective stresses. Applications include earthquake engineering, granular flow technologies (such as powder feed systems for pharmaceuticals and fertilizers), and terrestrial and planetary geology. Nine MGM specimens have flown on two Space Shuttle flights. Another three are scheduled to fly on STS-107. The principal investigator is Stein Sture of the University of Colorado at Boulder. (Credit: University of Colorado at Boulder).

  4. The configuration space of vibrated granular rings.

    NASA Astrophysics Data System (ADS)

    Daya, Zahir A.; Rivera, Michael K.; Ben-Naim, Eli; Ecke, Robert E.

    2003-03-01

    When granular chains, which consist of spherical beads connected by rods, are energetically excited by vertical vibration they explore the space of permissible geometric configurations. The size of the configuration space is determined by the physical constraints of the chain's construction and possibly by its dynamics. Under weak vibration when the chain is largely two-dimensional (2D) its configuration resembles a 2D self-avoiding walk (SAW). Here we consider chains whose ends are joined to form rings and compare them to SAWs that return to the origin. From large numbers of digital images of rings with N beads we estimate the size of the configuration space as a function of N. We obtain the estimate from an extrapolation of a coarse-grained counting of distinct configurations. The same procedure was applied to return-to-the-origin SAWs on a square lattice that were generated using Monte Carlo simulations. We compare our results with enumerations of SAWs and discuss the role of a configuration entropy for granular chains and generic filamentary objects such as flexible polymers and bio-macromolecules.

  5. Collisional model for granular impact dynamics.

    PubMed

    Clark, Abram H; Petersen, Alec J; Behringer, Robert P

    2014-01-01

    When an intruder strikes a granular material from above, the grains exert a stopping force which decelerates and stops the intruder. Many previous studies have used a macroscopic force law, including a drag force which is quadratic in velocity, to characterize the decelerating force on the intruder. However, the microscopic origins of the force-law terms are still a subject of debate. Here, drawing from previous experiments with photoelastic particles, we present a model which describes the velocity-squared force in terms of repeated collisions with clusters of grains. From our high speed photoelastic data, we infer that "clusters" correspond to segments of the strong force network that are excited by the advancing intruder. The model predicts a scaling relation for the velocity-squared drag force that accounts for the intruder shape. Additionally, we show that the collisional model predicts an instability to rotations, which depends on the intruder shape. To test this model, we perform a comprehensive experimental study of the dynamics of two-dimensional granular impacts on beds of photoelastic disks, with different profiles for the leading edge of the intruder. We particularly focus on a simple and useful case for testing shape effects by using triangular-nosed intruders. We show that the collisional model effectively captures the dynamics of intruder deceleration and rotation; i.e., these two dynamical effects can be described as two different manifestations of the same grain-scale physical processes. PMID:24580216

  6. Granular motions near the threshold of entrainment

    NASA Astrophysics Data System (ADS)

    Valyrakis, Manousos; Alexakis, athanasios-Theodosios

    2016-04-01

    Our society is continuously impacted by significant weather events many times resulting in catastrophes that interrupt our normal way of life. In the context of climate change and increasing urbanisation these "extreme" hydrologic events are intensified both in magnitude and frequency, inducing costs of the order of billions of pounds. The vast majority of such costs and impacts (even more to developed societies) are due to water related catastrophes such as the geomorphic action of flowing water (including scouring of critical infrastructure, bed and bank destabilisation) and flooding. New tools and radically novel concepts are in need, to enable our society becoming more resilient. This presentation, emphasises the utility of inertial sensors in gaining new insights on the interaction of flow hydrodynamics with the granular surface at the particle scale and for near threshold flow conditions. In particular, new designs of the "smart-sphere" device are discussed with focus on the purpose specific sets of flume experiments, designed to identify the exact response of the particle resting at the bed surface for various below, near and above threshold flow conditions. New sets of measurements are presented for particle entrainment from a Lagrangian viewpoint. Further to finding direct application in addressing real world challenges in the water sector, it is shown that such novel sensor systems can also help the research community (both experimentalists and computational modellers) gain a better insight on the underlying processes governing granular dynamics.

  7. Granular physics in low-gravity enviroments

    NASA Astrophysics Data System (ADS)

    Tancredi, G.; Maciel, A.; Heredia, L.; Richeri, P.; Nesmachnow, S.

    2011-10-01

    The granular media are formed by a set of macroscopic objects (named grains) which interact through temporal or permanent contacts. Several processes has been identified which require a full understanding, like: grain blocking, formation of arcs, size segregation, response to shakes and impacts, etc. These processes has been studied experimentally in the laboratory, and, in the last decades, numerically. The Discrete Element Method (DEM) simulate the mechanical behavior in a media formed by a set of particles which interact through their contact points. We describe the implementation of DEM for the study of several relevant processes in minor bodies of the Solar System. We present the results of simulations of the process of size segregation in low-gravity environments, the so-called Brazil nut effect, in the cases of Eros and Itokawa. The segregation of particles with different densities is also analyzed, with the application to the case of P/Hartley 2. The surface shaking in these different gravity environments could produce the ejection of particles from the surface at very low relative velocities. The shaking that cause the above processes is due to impacts or explosions like the release of energy by the liberation of internal stresses or the reaccommodation of material. We run simulations of the passage of seismic wave produced at impact through a granular media.

  8. Continuum equations for dense shallow granular flows

    NASA Astrophysics Data System (ADS)

    Kumaran, Viswanathan

    2015-11-01

    Simplified equations are derived for a granular flow in the `dense' limit where the volume fraction is close to that for dynamical arrest, and the `shallow' limit where the stream-wise length for flow development (L) is large compared to the cross-stream height (h). In the dense limit, the equations are simplified by taking advantage of the power-law divergence of the pair distribution function χ proportional to (ϕad - ϕ) - α, where ϕ is the volume fraction, and ϕad is the volume fraction for arrested dynamics. When the height h is much larger than the conduction length, the energy equation reduces to an algebraic balance between the rates of production and dissipation of energy, and the stress is proportional to the square of the strain rate (Bagnold law). The analysis reveals important differences between granular flows and the flows of Newtonian fluids. One important difference is that the Reynolds number (ratio of inertial and viscous terms) turns out to depend only on the layer height and Bagnold coefficients, and is independent of the flow velocity, because both the inertial terms in the conservation equations and the divergence of the stress depend on the square of the velocity/velocity gradients.

  9. Times Scales in Dense Granular Material

    NASA Astrophysics Data System (ADS)

    Zhang, Duan

    2005-07-01

    Forces in dense granular material are transmitted through particle contacts. The evolution of the contact stress is directly related to dynamical interaction forces between particles. Since particle contacts in a dense granular material are random, a statistical method is employed to describe and model their motions. It is found that the time scales of particle contacts determinate stress relaxation and the fluid- like or solid-like behavior of the material. Numerical simulations are performed to calculate statistical properties of particle interactions. Using results from the numerical simulations we examine the relationship between the averaged local deformation field and the macroscopic deformation field. We also examine the relationship between the averaged local interaction force and the averaged stress field in the material. Validities of the Voigt and the Reuss assumptions are examined; and extensions to these assumptions are studied. Numerical simulations show that tangential frictions between particles significantly increase the contact stress, while the direct contribution of the tangential force to the stress is small. This puzzling observation can be explained by dependency of the relaxation time on the tangential friction.

  10. Dynamics of random packings in granular flow

    NASA Astrophysics Data System (ADS)

    Rycroft, Chris H.; Bazant, Martin Z.; Grest, Gary S.; Landry, James W.

    2006-05-01

    We present a multiscale simulation algorithm for amorphous materials, which we illustrate and validate in a canonical case of dense granular flow. Our algorithm is based on the recently proposed spot model, where particles in a dense random packing undergo chainlike collective displacements in response to diffusing “spots” of influence, carrying a slight excess of interstitial free volume. We reconstruct the microscopic dynamics of particles from the “coarse grained” dynamics of spots by introducing a localized particle relaxation step after each spot-induced block displacement, simply to enforce packing constraints with a (fairly arbitrary) soft-core repulsion. To test the model, we study to what extent it can describe the dynamics of up to 135 000 frictional, viscoelastic spheres in granular drainage simulated by the discrete-element method (DEM). With only five fitting parameters (the radius, volume, diffusivity, drift velocity, and injection rate of spots), we find that the spot simulations are able to largely reproduce not only the mean flow and diffusion, but also some subtle statistics of the flowing packings, such as spatial velocity correlations and many-body structural correlations. The spot simulations run over 100 times faster than the DEM and demonstrate the possibility of multiscale modeling for amorphous materials, whenever a suitable model can be devised for the coarse-grained spot dynamics.

  11. Lizard locomotion in heterogeneous granular media

    NASA Astrophysics Data System (ADS)

    Schiebel, Perrin; Goldman, Daniel

    2014-03-01

    Locomotion strategies in heterogeneous granular environments (common substrates in deserts), are relatively unexplored. The zebra-tailed lizard (C. draconoides) is a useful model organism for such studies owing to its exceptional ability to navigate a variety of desert habitats at impressive speed (up to 50 body-lengths per second) using both quadrapedal and bidepal gaits. In laboratory experiments, we challenge the lizards to run across a field of boulders (2.54 cm diameter glass spheres or 3.8 cm 3D printed spheres) placed in a lattice pattern and embedded in a loosely packed granular medium of 0.3 mm diameter glass particles. Locomotion kinematics of the lizard are recorded using high speed cameras, with and without the scatterers. The data reveals that unlike the lizard's typical quadrupedal locomotion using a diagonal gait, when scatterers are present the lizard is most successful when using a bipedal gait, with a raised center of mass (CoM). We propose that the kinematics of bipedal running in conjunction with the lizard's long toes and compliant hind foot are the keys to this lizard's successful locomotion in the presence of such obstacles. NSF PoLS

  12. Quantifying exchange coupling in segregated granular materials

    NASA Astrophysics Data System (ADS)

    Morrison, C.; Saharan, L.; Ikeda, Y.; Takano, K.; Hrkac, G.; Thomson, T.

    2013-11-01

    The volume of a magnetic grain, together with its anisotropy, determines the probability of thermally activated reversal. Thus for grain volume distributions where the median volume is close to the superparamagnetic limit there will be a sub-set of grains which are either superparamagnetic on the time scale of a typical magnetic measurement (10 s), or the reverse due to magnetostatic fields from surrounding grains. We use this effect to probe exchange coupling in segregated granular materials, using CoCrPt-SiOx granular recording media as model systems. As the film thickness is reduced below 10 nm, the remanent magnetization of these films decreases, due to thermal activation and magnetostatic reversal. Varying film thickness and temperature allows us to thermally select a population of grains that contribute to the measurement. Exchange coupling is characterized by the angle dependence of remanent coercivity where we associate a breaking of symmetry from the Stoner-Wohlfarth model towards the Kondorsky model as a measure of the incoherency of reversal. Combining these models allows an estimate to be made of the volume fraction of grains that are exchange coupled and we find that, for well segregated CoCrPt-SiOx media, approximately 8% of the magnetic volume undergoes some degree of exchange coupling.

  13. Phase variation of hadronic amplitudes

    SciTech Connect

    Dedonder, J.-P.; Gibbs, W. R.; Nuseirat, Mutazz

    2008-04-15

    The phase variation with angle of hadronic amplitudes is studied with a view to understanding the underlying physical quantities that control it and how well it can be determined in free space. We find that unitarity forces a moderately accurate determination of the phase in standard amplitude analyses but that the nucleon-nucleon analyses done to date do not give the phase variation needed to achieve a good representation of the data in multiple scattering calculations. Models are examined that suggest its behavior near forward angles is related to the radii of the real and absorptive parts of the interaction. The dependence of this phase on model parameters is such that if these radii are modified in the nuclear medium (in combination with the change due to the shift in energy of the effective amplitude in the medium) then the larger magnitudes of the phase needed to fit the data might be attainable but only for negative values of the phase variation parameter.

  14. Very large hadron collider (VLHC)

    SciTech Connect

    1998-09-01

    A VLHC informal study group started to come together at Fermilab in the fall of 1995 and at the 1996 Snowmass Study the parameters of this machine took form. The VLHC as now conceived would be a 100 TeV hadron collider. It would use the Fermilab Main Injector (now nearing completion) to inject protons at 150 GeV into a new 3 TeV Booster and then into a superconducting pp collider ring producing 100 TeV c.m. interactions. A luminosity of {approximately}10{sup 34} cm{sup -2}s{sup -1} is planned. Our plans were presented to the Subpanel on the Planning for the Future of US High- Energy Physics (the successor to the Drell committee) and in February 1998 their report stated ``The Subpanel recommends an expanded program of R&D on cost reduction strategies, enabling technologies, and accelerator physics issues for a VLHC. These efforts should be coordinated across laboratory and university groups with the aim of identifying design concepts for an economically and technically viable facility`` The coordination has been started with the inclusion of physicists from Brookhaven National Laboratory (BNL), Lawrence Berkeley National Laboratory (LBNL), and Cornell University. Clearly, this collaboration must expanded internationally as well as nationally. The phrase ``economically and technically viable facility`` presents the real challenge.

  15. Hadron-hadron interaction from SU(2) lattice QCD

    SciTech Connect

    Takahashi, Toru T.; Kanada-En'yo, Yoshiko

    2010-11-01

    We evaluate interhadron interactions in two-color lattice QCD from Bethe-Salpeter amplitudes on the Euclidean lattice. The simulations are performed in quenched SU(2) QCD with the plaquette gauge action at {beta}=2.45 and the Wilson quark action. We concentrate on S-wave scattering states of two scalar diquarks. Evaluating different flavor combinations with various quark masses, we try to find out the ingredients in hadronic interactions. Between two scalar diquarks (uC{gamma}{sub 5}d, the lightest baryon in SU(2) system), we observe repulsion in short-range region, even though present quark masses are not very light. We define and evaluate the quark-exchange part in the interaction, which is induced by adding quark-exchange diagrams, or equivalently, by introducing Pauli-blocking among some of quarks. The repulsive force in short-distance region arises only from the quark-exchange part and disappears when quark-exchange diagrams are omitted. We find that the strength of repulsion grows in light quark-mass regime, and its quark-mass dependence is similar to or slightly stronger than that of the color-magnetic interaction by one-gluon-exchange (OGE) processes. It is qualitatively consistent with the constituent-quark-model picture that a color-magnetic interaction among quarks is the origin of repulsion. We also find a universal long-range attractive force, which enters in any flavor channels of two scalar diquarks and whose interaction range and strength are quark-mass independent. The weak quark-mass dependence of interaction ranges in each component implies that meson-exchange contributions are small and subdominant, and the other contributions, e.g., flavor-exchange processes, color-Coulomb, or color-magnetic interactions, are considered to be predominant, in the quark-mass range we evaluated.

  16. Effect of inhomogeneous microstructure of granular layer on inter granular/inter layer exchange coupling in stacked perpendicular recording media

    NASA Astrophysics Data System (ADS)

    Tham, Kim Kong; Saito, Shin; Hasegawa, Daiji; Itagaki, Norikazu; Hinata, Shintaro; Ishibashi, Shinichi; Takahashi, Migaku

    2012-11-01

    The effect of inhomogeneous microstructure of granular layer on inter granular/inter layer exchange coupling in stacked perpendicular recording media is studied by varying SiO2 content of CoCrPt-SiO2 granular layer. From cross-section and plane-view TEM observation, it can be concluded that each magnetic grain at cap layer (CL) grows on one magnetic grain of granular layer (GL), and inhomogeneous nucleation site at GL leads to inhomogeneous initial growth of continuous layer at CL. This phenomenon leads to the increase of inter granular coupling fluctuation in CL. Evaluation of inter granular coupling between magnetic grains at GL in stacked media with CL deposited directly on GL shows average and fluctuation of exchange coupling constant of around 2.9 erg/cm2 and 0.6 erg/cm2. In order to reduce the inter granular coupling, spacer layer (SL) with Pd material was inserted between GL and CL. As a result, average and fluctuation of exchange coupling constant decrease to 1.4 erg/cm2 and 0.3 erg/cm2 which suggests that by inserting a SL with small ferromagnetic exchange coupling between GL and CL will make it possible to control the inter granular coupling between magnetic grains at GL with CoCrPt-oxide material.

  17. a Unified Approach to Hadron-Hadron Hadron-Nucleus and Nucleus-Nucleus Collisions at High Energy

    NASA Astrophysics Data System (ADS)

    Wang, Xin-Nian

    The problem of multiparticle production in high -energy hadron-hadron, hadron-nucleus and nucleus-nucleus collisions are studied systematically in the framework of the Geometrical Branching Model (GBM). The model is based on the geometrical properties of nucleons and the stochastic nature of the interaction among the soft partons. The eikonal formalism is used to relate the elastic and inelastic cross sections and AGK cutting rule is used in connection with the multiparticle production process. The stochastic process of Furry branching is employed to describe the proliferation and hadronization of partons which lead to the produced particles. The approach describes hh, hA and AA collisions in a unified formalism for c.m. energies less than 100 GeV. The result of multiplicity distribution of produced particles exhibits Koba-Nielsen-Olesen (KNO) scaling. The universality of KNO scaling breaks down due to the different geometrical sizes of the hadron and nuclei. For hA and AA collisions, the formalism of GBM allows the hadron to be broken (to h^') by the first collision; indeed, it is the attention given to h^'h and h ^'h^' collisions that distinguishes this work from other earlier investigations on the subject. All of the calculated results are in good agreement with experiments. A general Monte Carlo simulation of GBM for multiparticle production in hh, hA and AA collisions is also given. The particle productivity in particular is studied in detail and is contrasted from the case where quark-gluon plasma (QGP) is produced in the AA collisions. This work forms a definitive description of hadronic and nuclear collisions that can serve as a basis from which exotic features such as the formation of QGP can be recognized as signatures deviating from the normal background.

  18. Birth and growth of a granular jet.

    PubMed

    Royer, John R; Corwin, Eric I; Conyers, Bryan; Flior, Andrew; Rivers, Mark L; Eng, Peter J; Jaeger, Heinrich M

    2008-07-01

    The interaction between fine grains and the surrounding interstitial gas in a granular bed can lead to qualitatively new phenomena not captured in a simple, single-fluid model of granular flows. This is demonstrated by the granular jet formed by the impact of a solid sphere into a bed of loose, fine sand. Unlike jets formed by impact in fluids, this jet is actually composed of two separate components, an initial thin jet formed by the collapse of the cavity left by the impacting object stacked on top of a second, thicker jet which depends strongly on the ambient gas pressure. This complex structure is the result of an interplay between ambient gas, bed particles, and impacting sphere. Here we present the results of systematic experiments that combine measurements of the jet above the surface varying the release height, sphere diameter, container size, and bed material with x-ray radiography below the surface to connect the changing response of the bed to the changing structure of the jet. We find that the interstitial gas trapped by the low permeability of a fine-grained bed plays two distinct roles in the formation of the jet. First, gas trapped and compressed between grains prevents compaction, causing the bed to flow like an incompressible fluid and allowing the impacting object to sink deep into the bed. Second, the jet is initiated by the gravity driven collapse of the cavity left by the impacting object. If the cavity is large enough, gas trapped and compressed by the collapsing cavity can amplify the jet by directly pushing bed material upwards and creating the thick jet. As a consequence of these two factors, when the ambient gas pressure is decreased, there is a crossover from a nearly incompressible, fluidlike response of the bed to a highly compressible, dissipative response. Compaction of the bed at reduced pressure reduces the final depth of the impacting object, resulting in a smaller cavity and in the demise of the thick jet. PMID:18763946

  19. Discrete blasts in granular material yield two-stage process of cavitation and granular fountaining

    NASA Astrophysics Data System (ADS)

    Andrews, Robin; White, James; Dürig, Tobi; Zimanowski, Bernd

    2014-05-01

    A discrete blast within granular material, such as a single subterranean explosion within a debris-filled diatreme structure, is typically considered to produce a single uprush of material. Our experiments demonstrate that apparent "debris jet deposits" can be formed by a two-stage process of cavitation and subsequent granular fountaining. Bench-scale experiments reported here demonstrate that for a range of overpressures and depths, individual, discrete, buried gas blasts open space and expel particles from the blast site in two largely decoupled stages. Expanding gas initially pierces material nearest the blast source to open a cavity above it; then a fountain of grains rises from the source into the cavity. This staged motion dynamically segregates source grains from host-material grains, and the rates of cavity opening vs. fountain rise show a power-law decay relationship with initial pressure. Our experimental analysis has implications for maar-diatreme systems, field-scale detonation experiments, and underground nuclear testing.

  20. Discrete blasts in granular material yield two-stage process of cavitation and granular fountaining

    NASA Astrophysics Data System (ADS)

    Andrews, Robin G.; White, James D. L.; Dürig, Tobi; Zimanowski, Bernd

    2014-01-01

    A discrete blast within granular material, such as a single subterranean explosion within a debris-filled diatreme structure, is typically considered to produce a single uprush of material. Our experiments demonstrate that apparent "debris jet deposits" can be formed by a two-stage process of cavitation and subsequent granular fountaining. Bench-scale experiments reported here demonstrate that for a range of overpressures and depths, individual, discrete, buried gas blasts open space and expel particles from the blast site in two largely decoupled stages. Expanding gas initially pierces material nearest the blast source to open a cavity above it; then a fountain of grains rises from the source into the cavity. This staged motion dynamically segregates source grains from host-material grains, and the rates of cavity opening versus fountain rise show a power law decay relationship with initial pressure. Our experimental analysis has implications for maar-diatreme systems, field-scale detonation experiments, and underground nuclear testing.

  1. Enhanced selection of micro-aerobic pentachlorophenol degrading granular sludge.

    PubMed

    Lv, Yuancai; Chen, Yuancai; Song, Wenzhe; Hu, Yongyou

    2014-09-15

    Column-type combined reactors were designed to cultivate micro-aerobic pentachlorophenol (PCP) degrading granular sludge under oxygen-limited conditions (0.1-0.2 mgL(-1)) over 39-day experimental period. Micro-aerobic granular had both anaerobic activity (SMA: 2.34 mMCH4/hg VSS) and aerobic activity (SOUR: 2.21 mMO2/hg VSS). Metabolite analysis results revealed that PCP was sequentially dechlorinated to TCP, DCP, and eventually to MCP. Methanogens were not directly involved in the dechlorination of PCP, but might played a vital role in stabilizing the overall structure of the granule sludge. For Eubacteria, the Shannon Index (2.09 in inoculated granular sludge) increased both in micro-aerobic granular sludge (2.61) and PCP-degradation granular sludge (2.55). However, for Archaea, it decreased from 2.53 to 1.85 and 1.84, respectively. Although the Shannon Index demonstrated slight difference between micro-aerobic granular sludge and PCP-degradation granular sludge, the Principal Component Analysis (PCA) indicated obvious variance of the microbial composition, revealing significant effect of micro-aerobic condition and PCP on microbial community. Furthermore, nucleotide sequencing indicated that the main microorganisms for PCP degradation might be related to Actinobacterium and Sphingomonas. These results provided insights into situ bioremediation of environments contaminated by PCP and had practical implications for the strategies of PCP degradation. PMID:25151236

  2. Dispersive behavior and acoustic scaling in granular rocks

    NASA Astrophysics Data System (ADS)

    Carlos, Santos; Vanessa, Urdaneta; Ernesto, Medina; Xavier, García

    2013-06-01

    Handling and making decisions based on data taken at different scales is a critical issue in the design of exploration and production tasks in the oil industry. Acoustic data is the classical example of the integration of dissimilar scales (i.e. seismic, well logs, lab data) where there is a scale dependent velocity. An understanding of the acoustic dispersion phenomenon in granular samples is needed. A detailed numerical work was conducted in order to establish the relationship between frequency and propagation speed for an acoustical pulse induced in simulated granular materials. The granular samples were generated with different grain size distributions while porosity and pressure were targeted and kept invariant using the grain radii expansion method. A sinusoidal burst with frequencies from 10Hz to 1MHz was applied and the corresponding acoustical speeds were estimated for each frequency. A coherent sigmoid dispersion relationship was obtained for each granular sample. The asymptotic boundaries for the dispersion function reflect the limiting cases for the wavelength/heterogeneity ratio in the granular pack. The lower speed asymptote was explained as the mean field value while upper speed asymptote can be understood based on a ray theory approximation scaled by a parameter we defined as the "acoustic tortuosity factor". This factor reflects the intricate acoustical path due to the texture of the stress network developed in the granular samples and can be used together with the sigmoid dispersive relationship to describe and clarify the scale discrepancy between different source acoustic data in granular materials.

  3. Rare events in granular media: a volcanic-like explosion

    NASA Astrophysics Data System (ADS)

    Khain, Evgeniy; Sander, Leonard

    2015-11-01

    Granular matter is ubiquitous in nature and exhibits a variety of nontrivial phenomena. Within the same system, different regions of granular media can be at a solid or a gas phase. Here we focus on a granular Leidenfrost effect: a solid-like cluster is levitating above the ``hot'' granular gas. This state was observed experimentally, when granular matter was vertically vibrated in a two-dimensional container. This solid-gas coexistence can be described by using granular hydrodynamics, taking into account the viscosity divergence in the solid cluster. The approach is similar to the one employed in investigating solid-fluid coexistence in dense shear granular flows. We performed extensive molecular dynamics simulations of a simple model of inelastic hard spheres driven by a ``thermal'' bottom wall. Simulations showed that for low wall temperatures, the levitating cluster is stable, while for high wall temperatures, it breaks down, and a hot gas bursts out resembling a volcanic explosion. We found a hysteresis: for a wide range of bottom wall temperatures, both the clustering state and the volcanic state are stable. However, even if the system is at the (stable) clustering state, a volcanic explosion is possible: it is a rare event driven by large fluctuations. We propose a special simulation technique that allows investigating such rare events.

  4. Effective Interactions Between Intruders in Vibrated Granular Materials

    NASA Astrophysics Data System (ADS)

    Derby, Rachel; Utter, Brian

    2011-11-01

    Despite the strong fluctuations in a rapidly moving granular material, dissipation and correlations in collisions can lead to long range forces in granular materials. In this experiment, we study the long-range attraction between two objects when immersed in a vibrated granular system. Depending on the strength of vibration, a granular system can take the form of a gas or be fluidized. We place two large intruders in each of these systems to track the effective interactions between the intruders, varying frequency, amplitude, size of grains, and the shape of the intruder. In particular, we study the interaction of spheres in a granular gas and the effective force between plates in a granular fluid. Using image processing, we track the separation of the intruders over time. We find that parallel plates attract if they are separated by less than approximately 15 particle diameters and reach a final position in which one ordered layer of grains is between them. Granular gas experiments suggest a long-range interaction, but observed effects in the mean position are much weaker than the fluctuations. Ongoing work focuses on varying the vibration parameters (amplitude, frequency, & waveform) and increasing statistics.

  5. Bottom pressure scaling of vibro-fluidized granular matter

    PubMed Central

    Katsuragi, Hiroaki

    2015-01-01

    Vibrated granular beds show various interesting phenomena such as convection, segregation, and so on. However, its fundamental physical properties (e.g., internal pressure structure) have not yet been understood well. Thus, in this study, the bottom wall pressure in a vertically vibrated granular column is experimentally measured and used to reveal the nature of granular fluidization. The scaling method allows us to elucidate the fluidization (softening) degree of a vibrated granular column. The peak value of the bottom pressure pm is scaled as Γ, where pJ, d, g, ω, H, and Γ are the Janssen pressure, grain diameter, gravitational acceleration, angular frequency, height of the column, and dimensionless vibrational acceleration, respectively. This scaling implies that the pressure of vibrated granular matter is quite different from the classical pressure forms: static and dynamic pressures. This scaling represents the importance of geometric factors for discussing the behavior of vibro-fluidized granular matter. The scaling is also useful to evaluate the dissipation degree in vibro-fluidized granular matter. PMID:26602973

  6. Trapping and sorting active granular rods

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Sriram; Kumar, Nitin; Soni, Harsh; Gupta, Rahul; Sood, Ajay

    We report experiments and simulations on collective trapping in a horizontal monolayer of tapered granular rods rendered motile by mechanical vibration. A macroscopic fraction of the particles are trapped by a V-shaped obstacle if its opening angle is less than a threshold value of about 120 degrees, consistent with active Brownian simulations [PRL 108, 268307 (2012)]. the transition between trapped and untrapped states becomes sharper with increasing system size in our numerical studies. We offer a theoretical understanding of this nonequilibrium phase transition based on collective noise suppression and an analysis of fluxes. We show also that the trap can serve to separate particles based on their motility and rotational diffusivity. On leave from Dept of Physics, Indian Institute of Science.

  7. Sound pulse broadening in stressed granular media.

    PubMed

    Langlois, Vincent; Jia, Xiaoping

    2015-02-01

    The pulse broadening and decay of coherent sound waves propagating in disordered granular media are investigated. We find that the pulse width of these compressional waves is broadened when the disorder is increased by mixing the beads made of different materials. To identify the responsible mechanism for the pulse broadening, we also perform the acoustic attenuation measurement by spectral analysis and the numerical simulation of pulsed sound wave propagation along one-dimensional disordered elastic chains. The qualitative agreement between experiment and simulation reveals a dominant mechanism by scattering attenuation at the high-frequency range, which is consistent with theoretical models of sound wave scattering in strongly random media via a correlation length. PMID:25768496

  8. Dynamics of gas-fluidized granular rods.

    PubMed

    Daniels, L J; Park, Y; Lubensky, T C; Durian, D J

    2009-04-01

    We study a quasi-two-dimensional monolayer of granular rods fluidized by a spatially and temporally homogeneous upflow of air. By tracking the position and orientation of the particles, we characterize the dynamics of the system with sufficient resolution to observe ballistic motion at the shortest time scales. Particle anisotropy gives rise to dynamical anisotropy and superdiffusive dynamics parallel to the rod's long axis, causing the parallel and perpendicular mean-square displacements to become diffusive on different time scales. The distributions of free times and free paths between collisions deviate from exponential behavior, underscoring the nonthermal character of the particle motion. The dynamics show evidence of rotational-translational coupling similar to that of an anisotropic Brownian particle. We model rotational-translational coupling in the single-particle dynamics with a modified Langevin model using nonthermal noise sources. This suggests a phenomenological approach to thinking about collections of self-propelling particles in terms of enhanced memory effects. PMID:19518218

  9. Dynamics of gas-fluidized granular rods

    NASA Astrophysics Data System (ADS)

    Daniels, L. J.; Park, Y.; Lubensky, T. C.; Durian, D. J.

    2009-04-01

    We study a quasi-two-dimensional monolayer of granular rods fluidized by a spatially and temporally homogeneous upflow of air. By tracking the position and orientation of the particles, we characterize the dynamics of the system with sufficient resolution to observe ballistic motion at the shortest time scales. Particle anisotropy gives rise to dynamical anisotropy and superdiffusive dynamics parallel to the rod’s long axis, causing the parallel and perpendicular mean-square displacements to become diffusive on different time scales. The distributions of free times and free paths between collisions deviate from exponential behavior, underscoring the nonthermal character of the particle motion. The dynamics show evidence of rotational-translational coupling similar to that of an anisotropic Brownian particle. We model rotational-translational coupling in the single-particle dynamics with a modified Langevin model using nonthermal noise sources. This suggests a phenomenological approach to thinking about collections of self-propelling particles in terms of enhanced memory effects.

  10. Rheology of U-Shaped Granular Particles

    NASA Astrophysics Data System (ADS)

    Hill, Matthew; Franklin, Scott

    We study the response of cylindrical samples of U-shaped granular particles (staples) to extensional loads. Samples elongate in discrete bursts (events) corresponding to particles rearranging and re-entangling. Previous research on samples of constant cross-sectional area found a Weibullian weakest-link theory could explain the distribution of yield points. We now vary the cross-sectional area, and find that the maximum yield pressure (force/area) is a function of particle number density and independent of area. The probability distribution function of important event characteristics -- the stress increase before an event and stress released during an event -- both fall of inversely with magnitude, reminiscent of avalanche dynamics. Fourier transforms of the fluctuating force (or stress) scales inversely with frequency, suggesting dry friction plays a role in the rearrangements. Finally, there is some evidence that dynamics are sensitive to the stiffness of the tensile testing machine, although an explanation for this behavior is unknown.

  11. Nonlinear Force Propagation During Granular Impact

    NASA Astrophysics Data System (ADS)

    Clark, Abram H.; Petersen, Alec J.; Kondic, Lou; Behringer, Robert P.

    2015-04-01

    We experimentally study nonlinear force propagation into granular material during impact from an intruder, and we explain our observations in terms of the nonlinear grain-scale force relation. Using high-speed video and photoelastic particles, we determine the speed and spatial structure of the force response just after impact. We show that these quantities depend on a dimensionless parameter, M'=tcv0/d , where v0 is the intruder speed at impact, d is the particle diameter, and tc is the collision time for a pair of grains impacting at relative speed v0. The experiments access a large range of M' by using particles of three different materials. When M'≪1 , force propagation is chainlike with a speed, vf, satisfying vf∝d /tc. For larger M', the force response becomes spatially dense and the force propagation speed departs from vf∝d /tc, corresponding to collective stiffening of a strongly compressed packing of grains.

  12. Frictional granular mechanics: A variational approach

    SciTech Connect

    Holtzman, R.; Silin, D.B.; Patzek, T.W.

    2009-10-16

    The mechanical properties of a cohesionless granular material are evaluated from grain-scale simulations. Intergranular interactions, including friction and sliding, are modeled by a set of contact rules based on the theories of Hertz, Mindlin, and Deresiewicz. A computer generated, three-dimensional, irregular pack of spherical grains is loaded by incremental displacement of its boundaries. Deformation is described by a sequence of static equilibrium configurations of the pack. A variational approach is employed to find the equilibrium configurations by minimizing the total work against the intergranular loads. Effective elastic moduli are evaluated from the intergranular forces and the deformation of the pack. Good agreement between the computed and measured moduli, achieved with no adjustment of material parameters, establishes the physical soundness of the proposed model.

  13. Dynamical approach to weakly dissipative granular collisions

    NASA Astrophysics Data System (ADS)

    Pinto, Italo'Ivo Lima Dias; Rosas, Alexandre; Lindenberg, Katja

    2015-07-01

    Granular systems present surprisingly complicated dynamics. In particular, nonlinear interactions and energy dissipation play important roles in these dynamics. Usually (but admittedly not always), constant coefficients of restitution are introduced phenomenologically to account for energy dissipation when grains collide. The collisions are assumed to be instantaneous and to conserve momentum. Here, we introduce the dissipation through a viscous (velocity-dependent) term in the equations of motion for two colliding grains. Using a first-order approximation, we solve the equations of motion in the low viscosity regime. This approach allows us to calculate the collision time, the final velocity of each grain, and a coefficient of restitution that depends on the relative velocity of the grains. We compare our analytic results with those obtained by numerical integration of the equations of motion and with exact ones obtained by other methods for some geometries.

  14. Hyperstaticity and loops in frictional granular packings

    NASA Astrophysics Data System (ADS)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  15. Granular acoustic switches and logic elements

    NASA Astrophysics Data System (ADS)

    Li, Feng; Anzel, Paul; Yang, Jinkyu; Kevrekidis, Panayotis G.; Daraio, Chiara

    2014-10-01

    Electrical flow control devices are fundamental components in electrical appliances and computers; similarly, optical switches are essential in a number of communication, computation and quantum information-processing applications. An acoustic counterpart would use an acoustic (mechanical) signal to control the mechanical energy flow through a solid material. Although earlier research has demonstrated acoustic diodes or circulators, no acoustic switches with wide operational frequency ranges and controllability have been realized. Here we propose and demonstrate an acoustic switch based on a driven chain of spherical particles with a nonlinear contact force. We experimentally and numerically verify that this switching mechanism stems from a combination of nonlinearity and bandgap effects. We also realize the OR and AND acoustic logic elements by exploiting the nonlinear dynamical effects of the granular chain. We anticipate these results to enable the creation of novel acoustic devices for the control of mechanical energy flow in high-performance ultrasonic devices.

  16. Traffic jams, granular flow, and soliton selection

    SciTech Connect

    Kurtze, D.A.; Hong, D.C.

    1995-07-01

    The flow of traffic on a long section of road without entrances or exits can be modeled by continuum equations similar to those describing fluid flow. In a certain range of traffic density, steady flow becomes unstable against the growth of a cluster, or ``phantom`` traffic jam, which moves at a slower speed than the otherwise homogeneous flow. We show that near the onset of this instability, traffic flow is described by a perturbed Korteweg--de Vries (KdV) equation. The traffic jam can be identified with a soliton solution of the KdV equation. The perturbation terms select a unique member of the continuous family of KdV solitons. These results may also apply to the dynamics of granular relaxation.

  17. "Pesta": New Granular Formulations for Steinernema carpocapsae

    PubMed Central

    Connick, W. J.; Nickle, W. R.; Vinyard, B. T.

    1993-01-01

    "Pesta," a new granular product for use with entrapped biocontrol agents, is based on a cohesive dough made of wheat flour, fillers, and other additives. Infective juveniles of the entomopathogen Steinernema carpocapsae strain All incorporated in Pesta granules emerged when the granules were softened by immersion in water. These granules may be useful for the biocontrol of insect pests in the soil. Storage temperature had the greatest effect on recovery of nematodes, followed by the moisture content of the granules. Recovery of nematodes was the same among the formulations tested and was unaffected by storage in nitrogen. Nematode recovery after storage at 21 C decreased to zero after 3-6 weeks. Storage of samples at 4 C and with a high moisture content (19.9-23.1%) greatly improved nematode viability. PMID:19279759

  18. Granular cell leiomyosarcoma of the skin

    SciTech Connect

    Suster, S.; Rosen, L.B.; Sanchez, J.L.

    1988-06-01

    A case is presented of a multifocal malignant neoplasm involving the skin of the upper back in a 10-year-old boy following radiation therapy to the head and neck for a cerebellar medulloblastoma. Histologically, the neoplastic cells were remarkable for the presence of abundant periodic acid-Schiff (PAS)-positive diastase-resistant intracytoplasmic eosinophilic granules. Immunoperoxidase procedures revealed strong positive staining of the tumor cells with desmin, vimentin, and smooth muscle myosin antibodies, and negative staining for myoglobin, S-100 protein and keratin, thus supporting a smooth muscle line of differentiation for this neoplasm. Electronmicroscopy demonstrated numerous intracytoplasmic autophagic vacuoles that corresponded to the granules observed under the light microscope. Leiomyosarcoma should be entertained in the differential diagnosis of poorly differentiated cutaneous neoplasms histologically characterized by a proliferation of cells containing abundant granular eosinophilic cytoplasm.

  19. Hydrodynamics of granular gases of viscoelastic particles.

    PubMed

    Brilliantov, Nikolai V; Pöschel, Thorsten

    2002-03-15

    Our study examines the long-time behaviour of a force-free granular gas of viscoelastic particles, for which the coefficient of restitution depends on the impact velocity, as it follows from the solution of the impact problem for viscoelastic spheres. Starting from the Boltzmann equation, we derived the hydrodynamic equations and obtained microscopic expressions for the transport coefficients in terms of the elastic and dissipative parameters of the particle material. We performed the stability analysis of the linearized set of equations and found that any inhomogeneities and vortices vanish after a long time and the system approaches the flow-free stage of homogeneous density. This behaviour is in contrast to that of a gas consisting of particles which interact via a (non-realistic) constant coefficient of restitution, for which inhomogeneities (clusters) and vortex patterns have been proven to arise and to continuously develop. PMID:16214686

  20. Granular structure determined by terahertz scattering

    NASA Astrophysics Data System (ADS)

    Born, Philip; Rothbart, Nick; Sperl, Matthias; Hübers, Heinz-Wilhelm

    2014-05-01

    Light scattering from particles reveals static and dynamical information about the particles and their correlations. Such methods are particularly powerful when the wavelength of the light is chosen similar to the sizes and distances of the particles. To apply scattering to investigate granular matter in particular —or other objects of similar submillimeter size— light of suitable wavelength in the terahertz regime needs to be chosen. By using a quantum cascade laser in a benchtop setup we determine the angle-dependent scattering of spherical particles as well as coffee powder and sugar grains. The scattering from single particles can be interpreted by form factors derived within the Mie theory. In addition, collective correlations can be extracted as static structure factors and compared to recent computer simulations.

  1. Hydrodynamic model for a vibrofluidized granular bed

    NASA Astrophysics Data System (ADS)

    Martin, T. W.; Huntley, J. M.; Wildman, R. D.

    2005-07-01

    Equations relating the energy flux, energy dissipation rate, and pressure within a three-dimensional vibrofluidized bed are derived and solved numerically, using only observable system properties, such as particle number, size, mass and coefficient of restitution, to give the granular temperature and packing fraction distributions within the bed. These are compared with results obtained from positron emission particle tracking experiments and the two are found to be in good agreement, without using fitting parameters, except at high altitudes when using a modified heat law including a packing fraction gradient term. Criteria for the onset of the Knudsen regime are proposed and the resulting temperature profiles are found to agree more closely with the experimental distributions. The model is then used to predict the scaling relationship between the height of the centre of mass and mean weighted bed temperature with the number of particles in the system and the excitation level.

  2. Laws of granular solids: geometry and topology.

    PubMed

    DeGiuli, Eric; McElwaine, Jim

    2011-10-01

    In a granular solid, mechanical equilibrium requires a delicate balance of forces at the disordered grain scale. To understand how macroscopic rigidity can emerge in this amorphous solid, it is crucial that we understand how Newton's laws pass from the disordered grain scale to the laboratory scale. In this work, we introduce an exact discrete calculus, in which Newton's laws appear as differential relations at the scale of a single grain. Using this calculus, we introduce gauge variables that describe identically force- and torque-balanced configurations. In a first, intrinsic formulation, we use the topology of the contact network, but not its geometry. In a second, extrinsic formulation, we introduce geometry with the Delaunay triangulation. These formulations show, with exact methods, how topology and geometry in a disordered medium are related by constraints. In particular, we derive Airy's expression for a divergence-free, symmetric stress tensor in two and three dimensions. PMID:22181138

  3. Penetration drag in loosely packed granular materials

    NASA Astrophysics Data System (ADS)

    Bless, Stephan; Omidvar, Mehdi; Iskander, Magued; New York University Collaboration

    2015-03-01

    The drag coefficient for penetration of granular materials by conical-nosed penetrators was computed by assuming the particles are non-interacting and rebound elastically off of the advancing penetrator. The solution was C =4 [sin(theta)]**2, where theta is the half angle of the cone. Experiments were conducted in which the drag coefficient was measured over the range 30 to 80 m/s for four types of sand: Ottawa silica sand, crushed quartz glass, coral sand, and aragonite sand. The sands were tested at relative densities of 40 and 80%. The drag coefficients for the low density materials were in excellent agreement with this simple model. The high density material had a drag considerably larger than predicted, presumably because of particle-to-particle interactions.

  4. Flocking at a distance in granular matter

    NASA Astrophysics Data System (ADS)

    Soni, Harsh; Ramaswamy, Sriram

    2015-03-01

    A mixture of polar granular rods and spherical beads on a vibrated plate undergoes a phase transition to an orientationally ordered state above a critical bead concentration. We study this system using large scale numerical simulations with periodic boundary conditions. We find an intermediate state with banded structures between the disordered and the globally ordered state. We observe a single band whose width increases with rod concentration. We find that at high densities the rods and the beads phase separate. We also test the various theoretical predictions of the hydrodynamic theory in the ordered state. Our results, which are in good agreement with the theory, are following: We see a highly anisotropic dispersion relation are exhibited with two sound modes in all directions except along the flock. Further the rods are super diffusive in the transverse direction and exhibit large number fluctuations.

  5. NMRI Measurements of Flow of Granular Mixtures

    NASA Technical Reports Server (NTRS)

    Nakagawa, Masami; Waggoner, R. Allen; Fukushima, Eiichi

    1996-01-01

    We investigate complex 3D behavior of granular mixtures in shaking and shearing devices. NMRI can non-invasively measure concentration, velocity, and velocity fluctuations of flows of suitable particles. We investigate origins of wall-shear induced convection flow of single component particles by measuring the flow and fluctuating motion of particles near rough boundaries. We also investigate if a mixture of different size particles segregate into their own species under the influence of external shaking and shearing disturbances. These non-invasive measurements will reveal true nature of convecting flow properties and wall disturbance. For experiments in a reduced gravity environment, we will design a light weight NMR imager. The proof of principle development will prepare for the construction of a complete spaceborne system to perform experiments in space.

  6. Pneumatic fractures in Confined Granular Media

    NASA Astrophysics Data System (ADS)

    Eriksen, Fredrik K.; Toussaint, Renaud; Jørgen Måløy, Knut; Grude Flekkøy, Eirik; Turkaya, Semih

    2016-04-01

    We will present our ongoing study of the patterns formed when air flows into a dry, non-cohesive porous medium confined in a horizontal Hele-Shaw cell. This is an optically transparent system consisting of two glass plates separated by 0.5 to 1 mm, containing a packing of dry 80 micron beads in between. The cell is rectangular and has an air-permeable boundary (blocking beads) at one short edge, while the other three edges are completely sealed. The granular medium is loosely packed against the semi-permeable boundary and fills about 80 % of the cell volume. This leaves an empty region at the sealed side, where an inlet allows us to set and maintain the air at a constant overpressure (0.1 - 2 bar). For the air trapped inside the cell to relax its overpressure it has to move through the deformable granular medium. Depending on the applied overpressure and initial density of the medium, we observe a range of different behaviors such as seepage through the pore-network with or without an initial compaction of the solid, formation of low density bubbles with rearrangement of particles, granular fingering/fracturing, and erosion inside formed channels/fractures. The experiments are recorded with a high-speed camera at a framerate of 1000 images/s and a resolution of 1024x1024 pixels. We use various image processing techniques to characterize the evolution of the air invasion patterns and the deformations in the surrounding material. The experiments are similar to deformation processes in porous media which are driven by pore fluid overpressure, such as mud volcanoes and hydraulic or pneumatic (gas-induced) fracturing, and the motivation is to increase the understanding of such processes by optical observations. In addition, this setup is an experimental version of the numerical models analyzed by Niebling et al. [1,2], and is useful for comparison with their results. In a directly related project [3], acoustic emissions from the cell plate are recorded during

  7. Thermoelectric and Seebeck coefficients of granular metals.

    SciTech Connect

    Glatz, A.; Beloborodov, I. S.; Materials Science Division; California State Univ.

    2009-01-01

    In this work we present a detailed study and derivation of the thermopower and thermoelectric coefficient of nanogranular metals at large tunneling conductance between the grains, g{sub T} >> 1. An important criterion for the performance of a thermoelectric device is the thermodynamic figure of merit which is derived using the kinetic coefficients of granular metals. All results are valid at intermediate temperatures, E{sub c} >> T/g{sub T} > {delta}, where {delta} is the mean energy-level spacing for a single grain and E{sub c} is its charging energy. We show that the electron-electron interaction leads to an increase in the thermopower with decreasing grain size and discuss our results in light of future generation thermoelectric materials for low-temperature applications. The behavior of the figure of merit depending on system parameters such as grain size, tunneling conductance, and temperature is presented.

  8. Defining and testing a granular continuum element

    SciTech Connect

    Rycroft, Chris H.; Kamrin, Ken; Bazant, Martin Z.

    2007-12-03

    Continuum mechanics relies on the fundamental notion of amesoscopic volume "element" in which properties averaged over discreteparticles obey deterministic relationships. Recent work on granularmaterials suggests a continuum law may be inapplicable, revealinginhomogeneities at the particle level, such as force chains and slow cagebreaking. Here, we analyze large-scale Discrete-Element Method (DEM)simulations of different granular flows and show that a "granularelement" can indeed be defined at the scale of dynamical correlations,roughly three to five particle diameters. Its rheology is rather subtle,combining liquid-like dependence on deformation rate and solid-likedependence on strain. Our results confirm some aspects of classicalplasticity theory (e.g., coaxiality of stress and deformation rate),while contradicting others (i.e., incipient yield), and can guide thedevelopment of more realistic continuum models.

  9. Active microrheology of driven granular particles.

    PubMed

    Wang, Ting; Grob, Matthias; Zippelius, Annette; Sperl, Matthias

    2014-04-01

    When pulling a particle in a driven granular fluid with constant force Fex, the probe particle approaches a steady-state average velocity v. This velocity and the corresponding friction coefficient of the probe ζ=Fex/v are obtained within a schematic model of mode-coupling theory and compared to results from event-driven simulations. For small and moderate drag forces, the model describes the simulation results successfully for both the linear as well as the nonlinear region: The linear response regime (constant friction) for small drag forces is followed by shear thinning (decreasing friction) for moderate forces. For large forces, the model demonstrates a subsequent increasing friction in qualitative agreement with the data. The square-root increase of the friction with force found in [Fiege et al., Granul. Matter 14, 247 (2012)] is explained by a simple kinetic theory. PMID:24827243

  10. Similarities between protein folding and granular jamming

    PubMed Central

    Jose, Prasanth P; Andricioaei, Ioan

    2012-01-01

    Grains and glasses, widely different materials, arrest their motions upon decreasing temperature and external load, respectively, in common ways, leading to a universal jamming phase diagram conjecture. However, unified theories are lacking, mainly because of the disparate nature of the particle interactions. Here we demonstrate that folded proteins exhibit signatures common to both glassiness and jamming by using temperature- and force-unfolding molecular dynamics simulations. Upon folding, proteins develop a peak in the interatomic force distributions that falls on a universal curve with experimentally measured forces on jammed grains and droplets. Dynamical signatures are found as a dramatic slowdown of stress relaxation upon folding. Together with granular similarities, folding is tied not just to the jamming transition, but a more nuanced picture of anisotropy, preparation protocol and internal interactions emerges. Results have implications for designing stable polymers and can open avenues to link protein folding to jamming theory. PMID:23093180

  11. Contact breaking in frictionless granular packings

    NASA Astrophysics Data System (ADS)

    Wu, Qikai; Bertrand, Thibault; O'Hern, Corey; Shattuck, Mark

    We numerically study the breaking of interparticle contact networks in static granular packings of frictionless bidisperse disks that are subjected to vibrations. The packings are created using an isotropic compression protocol at different values of the total potential energy per particle Ep. We first add displacements along a single vibrational mode i of the dynamical matrix to a given packing and calculate the minimum amplitude Ai of the perturbation at which the first interparticle contact breaks. We then identify the minimum amplitude Amin over all perturbations along each mode and study the distribution of Amin from an ensemble of packings at each Ep. We then study two-, three-, and multi-mode excitations and determine the dependence of Amin on the number of modes that are included in the perturbation. W. M. Keck Foundation Science and Engineering Grant.

  12. Moving Granular Bed Filter Development Program

    SciTech Connect

    Wilson, K.B.; Haas, J.C.; Gupta, R.P.; Turk, B.S.

    1996-12-31

    For coal-fired power plants utilizing a gas turbine, the removal of ash particles is necessary to protect the turbine and to meet emission standards. Advantages are also evident for a filter system that can remove other coal-derived contaminants such as alkali, halogens, and ammonia. With most particulates and other contaminants removed, erosion and corrosion of turbine materials, as well as deposition of particles within the turbine, are reduced to acceptable levels. The granular bed filter is suitable for this task in a pressurized gasification or combustion environment. The objective of the base contract was to develop conceptual designs of moving granular bed filter (GBF) and ceramic candle filter technologies for control of particles from integrated gasification combined cycle (IGCC), pressurized fluidized-bed combustion (PFBC), and direct coal-fueled turbine (DCFT) systems. The results of this study showed that the GBF design compared favorably with the candle filter. Three program options followed the base contract. The objective of Option I, Component Testing, was to identify and resolve technical issues regarding GBF development for IGCC and PFBC environments. This program was recently completed. The objective of Option II, Filter Proof Tests, is to test and evaluate the moving GBF system at a government-furnished hot-gas cleanup test facility. This facility is located at Southern Company Services (SCS), Inc., Wilsonville, Alabama. The objective of Option III, Multicontaminant Control Using a GBF, is to develop a chemically reactive filter material that will remove particulates plus one or more of the following coal-derived contaminants: alkali, halogens, and ammonia.

  13. Universal effective hadron dynamics from superconformal algebra

    NASA Astrophysics Data System (ADS)

    Brodsky, Stanley J.; de Téramond, Guy F.; Dosch, Hans Günter; Lorcé, Cédric

    2016-08-01

    An effective supersymmetric QCD light-front Hamiltonian for hadrons composed of light quarks, which includes a spin-spin interaction between the hadronic constituents, is constructed by embedding superconformal quantum mechanics into AdS space. A specific breaking of conformal symmetry inside the graded algebra determines a unique effective quark-confining potential for light hadrons, as well as remarkable connections between the meson and baryon spectra. The results are consistent with the empirical features of the light-quark hadron spectra, including a universal mass scale for the slopes of the meson and baryon Regge trajectories and a zero-mass pion in the limit of massless quarks. Our analysis is consistently applied to the excitation spectra of the π, ρ, K, K* and ϕ meson families as well as to the N, Δ, Λ, Σ, Σ*, Ξ and Ξ* in the baryon sector. We also predict the existence of tetraquarks which are degenerate in mass with baryons with the same angular momentum. The mass of light hadrons is expressed in a universal and frame-independent decomposition in the semiclassical approximation described here.

  14. Universal effective hadron dynamics from superconformal algebra

    DOE PAGESBeta

    Brodsky, Stanley J.; de Teramond, Guy F.; Dosch, Hans Gunter; Lorce, Cedric

    2016-05-25

    An effective supersymmetric QCD light-front Hamiltonian for hadrons composed of light quarks, which includes a spin–spin interaction between the hadronic constituents, is constructed by embedding superconformal quantum mechanics into AdS space. A specific breaking of conformal symmetry inside the graded algebra determines a unique effective quark-confining potential for light hadrons, as well as remarkable connections between the meson and baryon spectra. The results are consistent with the empirical features of the light-quark hadron spectra, including a universal mass scale for the slopes of the meson and baryon Regge trajectories and a zero-mass pion in the limit of massless quarks. Ourmore » analysis is consistently applied to the excitation spectra of the π , ρ , K , K* and Φ meson families as well as to the N , Δ, Λ, Σ, Σ* , Ξ and Ξ* in the baryon sector. Here, we also predict the existence of tetraquarks which are degenerate in mass with baryons with the same angular momentum. The mass of light hadrons is expressed in a universal and frame-independent decomposition in the semiclassical approximation described here.« less

  15. Evidences for two scales in hadrons

    SciTech Connect

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan; Povh, B.

    2007-11-01

    Some unusual features observed in hadronic collisions at high energies can be understood assuming that gluons in hadrons are located within small spots occupying only about 10% of the hadrons' area. Such a conjecture about the presence of two scales in hadrons helps to explain the following: why diffractive gluon radiation is so suppressed; why the triple-Pomeron coupling shows no t dependence; why total hadronic cross sections rise so slowly with energy; why diffraction cones shrink so slowly, and why {alpha}{sub P}{sup '}<<{alpha}{sub R}{sup '}; why the transition from hard to soft regimes in the structure functions occurs at rather large Q{sup 2}; why the observed Cronin effect at collider energies is so weak; why hard reactions sensitive to primordial parton motion (direct photon, Drell-Yan dileptons, heavy flavors, back-to-back dihadrons, seagull effect, etc.) demand such a large transverse momenta of the projectile partons, which is not explained by next-to-leading order calculations; why the onset of nuclear shadowing for gluons is so delayed compared to quarks; and why shadowing is so weak.

  16. Theoretical studies of hadrons and nuclei

    SciTech Connect

    COTANCH, STEPHEN R

    2007-03-20

    This report details final research results obtained during the 9 year period from June 1, 1997 through July 15, 2006. The research project, entitled Theoretical Studies of Hadrons and Nuclei , was supported by grant DE-FG02-97ER41048 between North Carolina State University [NCSU] and the U. S. Department of Energy [DOE]. In compliance with grant requirements the Principal Investigator [PI], Professor Stephen R. Cotanch, conducted a theoretical research program investigating hadrons and nuclei and devoted to this program 50% of his time during the academic year and 100% of his time in the summer. Highlights of new, significant research results are briefly summarized in the following three sections corresponding to the respective sub-programs of this project (hadron structure, probing hadrons and hadron systems electromagnetically, and many-body studies). Recent progress is also discussed in a recent renewal/supplemental grant proposal submitted to DOE. Finally, full detailed descriptions of completed work can be found in the publications listed at the end of this report.

  17. Granular cell tumor presenting as a large leg mass.

    PubMed

    Andalib, Ali; Heidary, Mohsen; Sajadieh-Khajouei, Sahar

    2014-10-01

    Granular cell tumor is a rare benign neoplasm most commonly appears in the head and neck region, especially in the tongue, cheek mucosa, and palate. Occurrence in limbs is even rarer. These tumors account for approximately 0.5% of all soft tissue tumors. Granular cell tumor can also affect other organs including skin, breast, and lungs. Local recurrence and metastasis is potentially higher in malignant forms with poor prognosis in respect to the benign counterparts. The average diameter of the tumor is usually about 2-3 cm. We report a granular cell tumor in the leg with an unusual size. PMID:25692157

  18. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  19. Technical Design of Hadron Therapy Facilities

    SciTech Connect

    Alonso, J.R.

    1993-08-01

    Radiation therapy with hadron beams now has a 40-year track record at many accelerator laboratories around the world, essentially all of these originally physics-research oriented. The great promise shown for treating cancer has led the medical community to seek dedicated accelerator facilities in a hospital setting, where more rapid progress can be made in clinical research. This paper will discuss accelerator and beam characteristics relevant to hadron therapy, particularly as applied to hospital-based facilities. A survey of currently-operating and planned hadron therapy facilities will be given, with particular emphasis on Lorna Linda (the first dedicated proton facility in a hospital) and HIMAC (the first dedicated heavy-ion medical facility).

  20. Basics of particle therapy: introduction to hadrons.

    PubMed

    Welsh, James S

    2008-10-01

    With the arrival of 3-dimensional conformal radiation therapy and intensity modulated radiation therapy, radiation dose distributions in radiation oncology have improved dramatically over the past couple of decades. As part of a natural progression there recently has been a resurgence of interest in hadron therapy, specifically charged particle therapy, because of the even better dose distributions potentially achievable. In principle, using charged particle beams, radiation dose distributions can be achieved that surpass those possible with even the most sophisticated photon radiation delivery techniques. Certain charged particle beams might possess some biologic advantages in terms of tumor kill potential as well as this dosimetric advantage. The particles under consideration for such clinical applications all belong to the category of particles known as hadrons. This review introduces some of the elementary physics of the various hadron species previously used, currently used or being considered for future use in radiation oncology. PMID:18838888

  1. Technical design of hadron therapy facilities

    SciTech Connect

    Alonso, J.R.

    1993-08-01

    Radiation therapy with hadron beams now has a 40-year track record at many accelerator laboratories around the world, essentially all of these originally physics-research oriented. The great promise shown for treating cancer has led the medical community to seek dedicated accelerator facilities in a hospital setting, where more rapid progress can be made in clinical research. This paper will discuss accelerator and beam characteristics relevant to hadron therapy, particularly as applied to hospital-based facilities. A survey of currently-operating and planned hadron therapy facilities will be given, with particular emphasis on Loma Linda (the first dedicated proton facility in a hospital) and HIMAC (the first dedicated heavy-ion medical facility).

  2. Nonequilibrium hadronization and constituent quark number scaling

    SciTech Connect

    Zschocke, Sven; Horvat, Szabolcs; Mishustin, Igor N.; Csernai, Laszlo P.

    2011-04-15

    The constituent quark number scaling of elliptic flow is studied in a nonequilibrium hadronization and freeze-out model with rapid dynamical transition from ideal, deconfined, and chirally symmetric quark-gluon plasma, to final noninteracting hadrons. In this transition a bag model of constituent quarks is considered, where the quarks gain constituent quark mass while the background bag field breaks up and vanishes. The constituent quarks then recombine into simplified hadron states, while chemical, thermal, and flow equilibrium break down one after the other. In this scenario the resulting temperatures and flow velocities of baryons and mesons are different. Using a simplified few source model of the elliptic flow, we are able to reproduce the constituent quark number scaling, with assumptions on the details of the nonequilibrium processes.

  3. Multi-hadron systems in lattice QCD

    SciTech Connect

    Will Detmold

    2009-07-01

    Lattice QCD is currently entering the stage when it can usefully be applied to systems of multiple hadrons. I briefly review the status of recent calculations of scattering parameters in the two hadron sector and discuss recent calculations of systems composed of many mesons or baryons. In the mesonic case, the NPLQCD collaboration has continued its study of systems of up to twelve pions or kaons and have computed the effect of such a hadronic medium on the static quark potential. High statistics calculations on anisotropic lattices have allowed for precision extraction of the energies and scattering phase shifts of various two baryon systems and, for the first time, the energies of certain three baryon systems have been computed.

  4. Hadronic form factors in kaon photoproduction

    SciTech Connect

    Syukurilla, L. Mart, T.

    2014-09-25

    We have revisited the effect of hadronic form factors in kaon photoproduction process by utilizing an isobaric model developed for kaon photoproduction off the proton. The model is able to reproduce the available experimental data nicely as well as to reveal the origin of the second peak in the total cross section, which was the main source of confusion for decades. Different from our previous study, in the present work we explore the possibility of using different hadronic form factors in each of the KΛN vertices. The use of different hadronic form factors, e.g. dipole, Gaussian, and generalized dipole, has been found to produce a more flexible isobar model, which can provide a significant improvement in the model.

  5. Hadron Production: Present Knowledge and Future Plans

    NASA Astrophysics Data System (ADS)

    Catanesi, M. G.

    2005-12-01

    Hadron production is a key ingredient in many aspects of neutrino physics. Precise prediction of atmospheric neutrino fluxes, characterization of accelerator neutrino beams, quantification of pion production and capture for neutrino factory designs, all of these would profit from hadron production measurements. For all these reasons this is a well established field since the '70s. In more recent times, low-energy hadron production experiments operating in the range from 1 GeV to 100 GeV are being operated, built or proposed. Such experiments all share a basic design, consisting in the presence of open-geometry spectrometers, as close as possible to full angular coverage, and the aim of full particle identification.

  6. Density-Dependent Relations among Properties of Hadronic Matter and Applications to Hadron-Quark Stars

    SciTech Connect

    Uechi, Hiroshi; Uechi, Schun T.

    2011-05-06

    Density-dependent relations among the saturation properties of symmetric nuclear matter and hyperonic matter, and properties of hadron-(strange) quark stars are shown by applying the conserving nonlinear {sigma}-{omega}-{rho} hadronic mean-field theory. Nonlinear interactions are renormalized self-consistently as effective coupling constants, effective masses, and sources of equations of motion by maintaining thermodynamic consistency to the mean-field approximation. Effective masses and coupling constants at the saturation point of symmetric nuclear matter simultaneously determine the binding energy and saturation properties of hyperonic matter. The coupling constants expected from the hadronic mean-field model and SU(6) quark model for the vector coupling constants are compared by calculating masses of hadron-quark neutron stars. The nonlinear {sigma}-{omega}-{rho} mean-field approximation with vacuum fluctuation corrections and strange quark matter defined by the MIT-bag model were employed to examine properties of hadron-(strange) quark stars. We found that hadron-(strange) quark stars become more stable at high densities compared to pure hadronic and strange quark stars.

  7. Top quark studies at hadron colliders

    SciTech Connect

    Sinervo, P.K.; CDF Collaboration

    1996-08-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag {ital b} quark jets in candidate events. The most recent measurements of top quark properties by the CDF and D{null} collaborations are reviewed, including the top quark cross section, mass, branching fractions and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  8. The QCD vacuum, hadrons and superdense matter

    SciTech Connect

    Shuryak, E.

    1986-01-01

    This is probably the only textbook available that gathers QCD, many-body theory and phase transitions in one volume. The presentation is pedagogical and readable. Contents: The QCD Vacuum: Introduction; QCD on the Lattice Topological Effects in Gauges Theories. Correlation Functions and Microscopic Excitations: Introduction; Operator Product Expansion; The Sum Rules beyond OPE; Nonpower Contributions to Correlators and Instantons; Hadronic Spectroscopy on the Lattice. Dense Matter: Hadronic Matter; Asymptotically Dense Quark-Gluon Plasma; Instantons in Matter; Lattice Calculations at Finite Temperature; Phase Transitions; Macroscopic Excitations and Experiments: General Properties of High Energy Collisions; ''Barometers'', ''Thermometers'', Interferometric ''Microscope''; Experimental Perspectives.

  9. Hadron polarizability data analysis: GoAT

    SciTech Connect

    Stegen, H. Hornidge, D.; Collicott, C.; Martel, P.; Ott, P.

    2015-12-31

    The A2 Collaboration at the Institute for Nuclear Physics in Mainz, Germany, is working towards determining the polarizabilities of hadrons from nonperturbative quantum chromodynamics through Compton scattering experiments at low energies. The asymmetry observables are directly related to the scalar and spin polarizabilities of the hadrons. Online analysis software, which will give real-time feedback on asymmetries, efficiencies, energies, and angle distributions, has been developed. The new software is a big improvement over the existing online code and will greatly develop the quality of the acquired data.

  10. High energy hadrons in extensive air showers

    NASA Technical Reports Server (NTRS)

    Tonwar, S. C.

    1985-01-01

    Experimental data on the high energy hadronic component in extensive air showers of energies approx. 10 to the 14 to 10 to the 16 eV when compared with expectations from Monte Carlo simulations have shown the observed showers to be deficient in high energy hadrons relative to simulated showers. An attempt is made to understand these anomalous features with more accurate comparison of observations with expectations, taking into account the details of the experimental system. Results obtained from this analysis and their implications for the high energy physics of particle interactions at energy approx. 10 to the 15 eV are presented.

  11. Top quark studies at hadron colliders

    SciTech Connect

    Sinervo, P.K.

    1997-01-01

    The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and DO Collaborations are reviewed, including the top quark cross section, mass, branching fractions, and production properties. Future top quark studies at hadron colliders are discussed, and predictions for event yields and uncertainties in the measurements of top quark properties are presented.

  12. Resummed Results for Hadron Collider Observables

    NASA Astrophysics Data System (ADS)

    McAslan, Heather

    2016-07-01

    Event shapes are invaluable QCD tools for theoretical calculations and experimental measurements. We revise the definition of these observables in e+e- annihilation and in hadron collisions, and give a review of the state-of-the-art results for their resummation. Then we detail how recent work on the re-summation of event shapes in electron-positron annihilation can provide us with the tools to extend resummation of generic hadronic event shapes to NNLL accuracy. We match our findings to fixed-order results at NNLO accuracy, showing the sizeable effects of resummation in the relevant regions of phase space.

  13. Hadron Physics at BaBar

    SciTech Connect

    Muller, David; /SLAC

    2005-10-26

    The BaBar experiment at SLAC is designed to measure CP violation in the B meson system, however the very high statistics combined with the different e{sup +} and e{sup -} beam energies, the detector design and the open trigger allow a wide variety of spectroscopic measurements. We are beginning to tap this potential via several production mechanisms. Here we present recent results from initial state radiation, hadronic jets, few body B and D hadron decays, and interactions in the detector material. We also summarize measurements relevant to D{sub s} meson spectroscopy, pentaquarks and charmonium spectroscopy from multiple production mechanisms.

  14. Precision Event Simulation for Hadron Colliders

    NASA Astrophysics Data System (ADS)

    Hoeche, Stefan

    2016-03-01

    Hadron colliders are workhorses of particle physics, enabling scientific breakthroughs such as the discovery of the Higgs boson. Hadron beams reach the highest energies, but they also produce very complex collisions. Studying the underlying dynamics requires involved multi-particle calculations. Over the past decades Monte-Carlo simulation programs were developed to tackle this task. They have by now evolved into precision tools for theorists and experimenters alike. This talk will give an introduction to event generators and discuss the current status of development.

  15. Hadronization via coalescence at RHIC and LHC

    NASA Astrophysics Data System (ADS)

    Minissale, V.; Scardina, F.; Greco, V.

    2016-05-01

    An hadronization model that includes coalescence and fragmentation is used in this work to obtain predictions at both RHIC and LHC energy for light and strange hadrons transverse momentum spectra (π, p, k, Λ) and baryon to meson ratios (p/π, Λ/k) in a wide range of pT. This is accomplished without changing coalescence parameters. The ratios p/π and Λ/K shows the right behaviour except for some lack of baryon yield in a limited pT range around 6 GeV. This would indicate that the AKK fragmentation functions is too flat at pT < 8 GeV.

  16. Hadron polarizability data analysis: GoAT

    NASA Astrophysics Data System (ADS)

    Stegen, H.; Collicott, C.; Hornidge, D.; Martel, P.; Ott, P.

    2015-12-01

    The A2 Collaboration at the Institute for Nuclear Physics in Mainz, Germany, is working towards determining the polarizabilities of hadrons from nonperturbative quantum chromodynamics through Compton scattering experiments at low energies. The asymmetry observables are directly related to the scalar and spin polarizabilities of the hadrons. Online analysis software, which will give real-time feedback on asymmetries, efficiencies, energies, and angle distributions, has been developed. The new software is a big improvement over the existing online code and will greatly develop the quality of the acquired data.

  17. A convex complementarity approach for simulating large granular flows.

    SciTech Connect

    Tasora, A.; Anitescu, M.; Mathematics and Computer Science; Univ. degli Studi di Parma

    2010-07-01

    Aiming at the simulation of dense granular flows, we propose and test a numerical method based on successive convex complementarity problems. This approach originates from a multibody description of the granular flow: all the particles are simulated as rigid bodies with arbitrary shapes and frictional contacts. Unlike the discrete element method (DEM), the proposed approach does not require small integration time steps typical of stiff particle interaction; this fact, together with the development of optimized algorithms that can run also on parallel computing architectures, allows an efficient application of the proposed methodology to granular flows with a large number of particles. We present an application to the analysis of the refueling flow in pebble-bed nuclear reactors. Extensive validation of our method against both DEM and physical experiments results indicates that essential collective characteristics of dense granular flow are accurately predicted.

  18. Dynamic shear of granular material under variable gravity conditions

    NASA Technical Reports Server (NTRS)

    White, B. R.; Klein, S. P.

    1988-01-01

    This paper describes some experiments with granular materials which recently have been conducted aboard the NASA KC-135 aircraft during variable gravity maneuvers. The main experimental apparatus consisted of a small drum containing granular material which was rotated slowly while the angle assumed by the slip surface with respect to the horizontal was observed and recorded photographically. Conventional wisdom has held that this 'dynamic angle of response' was a material constant, independent of (among other things) gravitational level. The results presented here are quite contrary, suggesting instead an angle that varies with the reciprocal of the square root of gravity. This finding may have important consequences on the understanding of many active processes in Planetary Geology involving granular materials and may provide qualitative confirmation of some of the theoretical predictions of modern models of granular shear flows.

  19. A flexible self-learning model based on granular computing

    NASA Astrophysics Data System (ADS)

    Wei, Ting; Wu, Yu; Li, Yinguo

    2007-04-01

    Granular Computing(GrC) is an emerging theory which simulates the process of human brain understanding and solving problems. Rough set theory is a tool for dealing with uncertainty and vagueness aspects of knowledge model. SMLGrC algorithm introduces GrC to classical rough set algorithms, and makes the length of the rules relatively short but it can not process mass data sets. In order to solve this problem, based on the analysis of the hierarchical granular model of information table, the method of Granular Distribution List(GDL) is introduced to generate granule, and a granular computing algorithm(SLMGrC) is improved. Sample Covered Factor(SCF) is also introduced to control the generation of rules when the algorithm generates conflicting rules. The improved algorithm can process mass data sets directly without influencing the validity of SLMGrC. Experiments demonstrated the validity and flexibility of our method.

  20. Pattern formation in wet granular matter under vertical vibrations.

    PubMed

    Butzhammer, Lorenz; Völkel, Simeon; Rehberg, Ingo; Huang, Kai

    2015-07-01

    Experiments on a thin layer of cohesive wet granular matter under vertical vibrations reveal kink-separated domains that collide with the container at different phases. Due to the strong cohesion arising from the formation of liquid bridges between adjacent particles, the domains move collectively upon vibrations. Depending on the periodicity of this collective motion, the kink fronts may propagate, couple with each other, and form rotating spiral patterns in the case of period tripling or stay as standing wave patterns in the case of period doubling. Moreover, both patterns may coexist with granular "gas bubbles"-phase separation into a liquidlike and a gaslike state. Stability diagrams for the instabilities measured with various granular layer mass m and container height H are presented. The onsets for both types of patterns and their dependency on m and H can be quantitatively captured with a model considering the granular layer as a single particle colliding completely inelastically with the container. PMID:26274155

  1. Reorganization of a granular medium around a localized transformation

    NASA Astrophysics Data System (ADS)

    Merceron, Aymeric; Sauret, Alban; Jop, Pierre

    2016-06-01

    Physical and chemical transformation processes in reactive granular media involve the reorganization of the structure. In this paper, we study experimentally the rearrangements of a two-dimensional (2D) granular packing undergoing a localized transformation. We track the position and evolution of all the disks that constitute the granular packing when either a large intruder shrinks in size or is pulled out of the granular structure. In the two situations the displacements at long time are similar to 2D quasistatic silo flows whereas the short-time dynamic is heterogeneous in both space and time. We observe an avalanchelike behavior with power-law distributed events uncorrelated in time. In addition, the instantaneous evolutions of the local solid fraction exhibit self-similar distributions. The averages and the standard deviations of the solid fraction variations can be rescaled, suggesting a single mechanism of rearrangement.

  2. Brownian motion in granular gases of viscoelastic particles

    SciTech Connect

    Bodrova, A. S. Brilliantov, N. V.; Loskutov, A. Yu.

    2009-12-15

    A theory is developed of Brownian motion in granular gases (systems of many macroscopic particles undergoing inelastic collisions), where the energy loss in inelastic collisions is determined by a restitution coefficient {epsilon}. Whereas previous studies used a simplified model with {epsilon} = const, the present analysis takes into account the dependence of the restitution coefficient on relative impact velocity. The granular temperature and the Brownian diffusion coefficient are calculated for a granular gas in the homogeneous cooling state and a gas driven by a thermostat force, and their variation with grain mass and size and the restitution coefficient is analyzed. Both equipartition principle and fluctuation-dissipation relations are found to break down. One manifestation of this behavior is a new phenomenon of 'relative heating' of Brownian particles at the expense of cooling of the ambient granular gas.

  3. Instationary compaction wave propagation in highly porous cohesive granular media

    NASA Astrophysics Data System (ADS)

    Gunkelmann, Nina; Ringl, Christian; Urbassek, Herbert M.

    2016-04-01

    We study the collision of a highly porous granular aggregate of adhesive μm-sized silica grains with a hard wall using a granular discrete element method. A compaction wave runs through the granular sample building up an inhomogeneous density profile. The compaction is independent of the length of the aggregate, within the regime of lengths studied here. Also short pulses, as they might be exerted by a piston pushing the granular material, excite a compaction wave that runs through the entire material. The speed of the compaction wave is larger than the impact velocity but considerably smaller than the sound speed. The wave speed is related to the compaction rate at the colliding surface and the average slope of the linear density profile.

  4. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  5. Impact Craters on Comets from a Granular Material Perspective

    NASA Astrophysics Data System (ADS)

    de Niem, D.; Kührt, E.

    2015-02-01

    The contribution applies an algorithm for finite-deformation elasticity and plasticity to demonstrate new results for the behaviour of granular materials during impact crater formation in a low-gravity environment.

  6. Reorganization of a granular medium around a localized transformation.

    PubMed

    Merceron, Aymeric; Sauret, Alban; Jop, Pierre

    2016-06-01

    Physical and chemical transformation processes in reactive granular media involve the reorganization of the structure. In this paper, we study experimentally the rearrangements of a two-dimensional (2D) granular packing undergoing a localized transformation. We track the position and evolution of all the disks that constitute the granular packing when either a large intruder shrinks in size or is pulled out of the granular structure. In the two situations the displacements at long time are similar to 2D quasistatic silo flows whereas the short-time dynamic is heterogeneous in both space and time. We observe an avalanchelike behavior with power-law distributed events uncorrelated in time. In addition, the instantaneous evolutions of the local solid fraction exhibit self-similar distributions. The averages and the standard deviations of the solid fraction variations can be rescaled, suggesting a single mechanism of rearrangement. PMID:27415344

  7. A universal scaling law for the evolution of granular gases

    NASA Astrophysics Data System (ADS)

    Hummel, Mathias; Clewett, James P. D.; Mazza, Marco G.

    2016-04-01

    Dry, freely evolving granular materials in a dilute gaseous state coalesce into dense clusters only due to dissipative interactions. Here we show that the evolution of a dilute, freely cooling granular gas is determined in a universal way by the ratio of inertial flow and thermal velocities, that is, the Mach number. Theoretical calculations and direct numerical simulations of the granular Navier-Stokes equations show that irrespective of the coefficient of restitution, density or initial velocity distribution, the density fluctuations follow a universal quadratic dependence on the system's Mach number. We find that the clustering exhibits a scale-free dynamics but the clustered state becomes observable when the Mach number is approximately of O(1) . Our results provide a method to determine the age of a granular gas and predict the macroscopic appearance of clusters.

  8. REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

  9. Instationary compaction wave propagation in highly porous cohesive granular media

    NASA Astrophysics Data System (ADS)

    Gunkelmann, Nina; Ringl, Christian; Urbassek, Herbert M.

    2016-07-01

    We study the collision of a highly porous granular aggregate of adhesive \\upmu m-sized silica grains with a hard wall using a granular discrete element method. A compaction wave runs through the granular sample building up an inhomogeneous density profile. The compaction is independent of the length of the aggregate, within the regime of lengths studied here. Also short pulses, as they might be exerted by a piston pushing the granular material, excite a compaction wave that runs through the entire material. The speed of the compaction wave is larger than the impact velocity but considerably smaller than the sound speed. The wave speed is related to the compaction rate at the colliding surface and the average slope of the linear density profile.

  10. A universal scaling law for the evolution of granular gases

    NASA Astrophysics Data System (ADS)

    Hummel, Mathias; Clewett, James; Mazza, Marco G.

    Dry, freely evolving granular materials in a dilute gaseous state coalesce into dense clusters only due to dissipative interactions. This clustering transition is important for a number of problems ranging from geophysics to cosmology. Here we show that the evolution of a dilute, freely cooling granular gas is determined in a universal way by the ratio of inertial flow and thermal velocities, that is, the Mach number. Theoretical calculations and direct numerical simulations of the granular Navier-Stokes equations show that irrespective of the coefficient of restitution, density or initial velocity distribution, the density fluctuations follow a universal quadratic dependence on the system's Mach number. We find that the clustering exhibits a scale-free dynamics but the clustered state becomes observable when the Mach number is approximately of O(1). Our results provide a method to determine the age of a granular gas and predict the macroscopic appearance of clusters.

  11. Numerical study of axisymmetric collapses of submarine granular > columns

    NASA Astrophysics Data System (ADS)

    Monsorno, Davide; Varsakelis, Christos

    2014-11-01

    In this talk, we report on the results of a numerical study of the axisymmetric collapse of subaqueous granular columns. Our study is based on a 2-pressure, 2-velocity continuum flow model for fluid-saturated granular materials. This model is integrated via a multi-phase projection method that incorporates a regularization method for the treatment of material interfaces. In our simulations, a dense column of a granular material immersed in water is placed on a horizontal plane and is allowed to collapse and spread due to its weight. Emphasis is placed on the run-out distance and the termination height and their correlation with the aspect ratio, the volume fraction and the diameter of the grains. Comparisons against experimental measurements and previous numerical predictions are also performed. Finally, in order to examine and quantify the role of the interstitial fluid, we compare our numerical predictions against experimental results from column collapses of dry granular materials.

  12. Simulations of secondary currents in rapid granular chute flow

    NASA Astrophysics Data System (ADS)

    Calantoni, Joseph; Finn, Justin; Simeonov, Julian; Bateman, Samuel

    2014-11-01

    The desire to understand granular flow as a fluid mechanical phenomena has long been the focus of theoreticians and experimentalists alike. Several analogies can be drawn with complex hydrodynamic behaviors at the continuum scale including Leidenfrost states, Rayleigh-Benard (R-B) convection, and Rayleigh-Taylor instability that allow for deeper understanding of collective granular motions. Here, we consider the case of longitudinal vortices in rapid granular flow down an inclined chute, and draw an analogy to hydraulic open channel flow. Previous experiments of rapid granular flow down inclined chutes have uncovered a unique regime where the flow exhibits stripes of slower and faster moving grains. We present results of molecular dynamics simulations that allowed us to study the full scale of the phenomena including smooth sidewalls and the rough bumpy bottom. We found that the secondary currents were intensified near the lateral walls.

  13. Penetration of spherical projectiles into wet granular media.

    PubMed

    Birch, S P D; Manga, M; Delbridge, B; Chamberlain, M

    2014-09-01

    We measure experimentally the penetration depth d of spherical particles into a water-saturated granular medium made of much smaller sand-sized grains. We vary the density, size R, and velocity U of the impacting spheres, and the size δ of the grains in the granular medium. We consider velocities between 7 and 107 m/s, a range not previously addressed, but relevant for impacts produced by volcanic eruptions. We find that d∝R(1/3)δ(1/3)U(2/3). The scaling with velocity is similar to that identified in previous, low-velocity collisions, but it also depends on the size of the grains in the granular medium. We develop a model, consistent with the observed scaling, in which the energy dissipation is dominated by the work required to rearrange grains along a network of force chains in the granular medium. PMID:25314438

  14. DISINFECTION OF BACTERIA ATTACHED TO GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon (GAC) particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected wit...

  15. Enstrophy cascades in two-dimensional dense granular flows.

    PubMed

    Saitoh, Kuniyasu; Mizuno, Hideyuki

    2016-08-01

    Employing two-dimensional molecular dynamics simulations of dense granular materials under simple shear deformations, we investigate vortex structures of particle rearrangements. Introducing vorticity fields as a measure of local spinning motions of the particles, we observe their heterogeneous distributions, where statistics of vorticity fields exhibit the highly non-Gaussian behavior and typical domain sizes of vorticity fields significantly increase if the system is yielding under quasistatic deformations. In such dense granular flows, a power-law decay of vorticity spectra can be observed at mesoscopic scale, implying anomalous local structures of kinetic energy dissipation. We explain the power-law decay, or enstrophy cascades in dense granular materials, by a dimensional analysis, where the dependence of vorticity spectra not only on the wave number, but also on the shear rate, is well explained. From our dimensional analyses, the scaling of granular temperature and rotational kinetic energy is also predicted. PMID:27627381

  16. Eosinophilic and granular cell tumors of the breast.

    PubMed

    Damiani, S; Dina, R; Eusebi, V

    1999-05-01

    Eosinophilic and granular cell tumors of the breast are a heterogeneous group encompassing both epithelial and mesenchymal lesions. A granular appearance of the cytoplasm may be caused by the accumulation of secretory granules, mitochondria, or lysosomes. In the breast, mucoid carcinomas, carcinomas showing apocrine differentiation, and neuroendocrine carcinomas are well known entities, while tumors with oncocytic and acinic cell differentiation have been only recently recognized. An abundance of lysosomes is characteristic of Schwannian granular cell neoplasms, but smooth muscle cell tumors also may have this cytoplasmic feature. Awareness of all these possibilities when granular cells are found in breast lesions improves diagnostic accuracy and helps to avoid misdiagnosis of both benign lesions and malignant tumors. PMID:10452577

  17. BOOK REVIEW: Kinetic Theory of Granular Gases

    NASA Astrophysics Data System (ADS)

    Trizac, Emmanuel

    2005-11-01

    Granular gases are composed of macroscopic bodies kept in motion by an external energy source such as a violent shaking. The behaviour of such systems is quantitatively different from that of ordinary molecular gases: due to the size of the constituents, external fields have a stronger effect on the dynamics and, more importantly, the kinetic energy of the gas is no longer a conserved quantity. The key role of the inelasticity of collisions has been correctly appreciated for about fifteen years, and the ensuing consequences in terms of phase behaviour or transport properties studied in an increasing and now vast body of literature. The purpose of this book is to help the newcomer to the field in acquiring the essential theoretical tools together with some numerical techniques. As emphasized by the authors—who were among the pioneers in the domain— the content could be covered in a one semester course for advanced undergraduates, or it could be incorporated in a more general course dealing with the statistical mechanics of dissipative systems. The book is self-contained, clear, and avoids mathematical complications. In order to elucidate the main physical ideas, heuristic points of views are sometimes preferred to a more rigorous route that would lead to a longer discussion. The 28 chapters are short; they offer exercises and worked examples, solved at the end of the book. Each part is supplemented with a relevant foreword and a useful summary including take-home messages. The editorial work is of good quality, with very few typographical errors. In spite of the title, kinetic theory stricto sensu is not the crux of the matter covered. The authors discuss the consequences of the molecular chaos assumption both at the individual particle level and in terms of collective behaviour. The first part of the book addresses the mechanics of grain collisions. It is emphasized that considering the coefficient of restitution ɛ —a central quantity governing the

  18. Quantum chromodynamic quark model study of hadron and few hadron systems

    SciTech Connect

    Ji, Chueng-Ryong.

    1990-10-01

    This report details research progress and results obtained during the five month period July 1, 1990 to November 30, 1990. The research project, entitled Quantum Chromodynamic Quark Model Study of Hadron and Few Hadron Systems,'' is supported by grant FG05-90ER40589 between North Carolina State University and the United States Department of Energy. This is a research program addressing theoretical investigations of hadron structure and reactions using quantum chromodynamic quark models. The new, significant research results are briefly summarized in the following sections.

  19. Nonuniversal gaugino and scalar masses, hadronically quiet trileptons, and the Large Hadron Collider

    SciTech Connect

    Bhattacharya, Subhaditya; Datta, AseshKrishna; Mukhopadhyaya, Biswarup

    2008-12-01

    We investigate the parameter space of the minimal supersymmetric standard model where the gluino and squark masses are much above 1 TeV but the remaining part of the sparticle spectrum is accessible to the Large Hadron Collider at CERN. After pointing out that such a scenario may constitute an important benchmark of gaugino/scalar nonuniversality, we find that hadronically quiet trileptons are rather useful signals for it. Regions of the parameter space, where the signal is likely to be appreciable, are identified through a detailed scan. The advantage of hadronically quiet trileptons over other types of signals is demonstrated.

  20. Particle deposition in granular media. Annual progress report

    SciTech Connect

    Tien, C.

    1980-01-01

    Studies performed under Contract DE-AC02-79-ER10386.A000 Particle Deposition in Granular Media during the period June 1, 1979 to date are described. These studies include the design and construction of apparatus for filtration experiments and a complete trajectory analysis for the calculation of the initial collection efficiency of granular media. The results of the trajectory analysis have been used to develop a generalized correlation of the collection efficiency.

  1. Dynamics of Granular Materials and Particle-Laden Flows

    SciTech Connect

    Swinney, Harry L.

    2007-07-11

    Rapid granular flows and particle-laden flows were studied in laboratory experiments, molecular dynamics simulations, and simulations of continuum equations. The research demonstrated that the inclusion of friction is crucial in realistic modeling of granular flows; hence extensive previous analyses and simulations by many researchers for frictionless particles must be reconsidered in the light of our work. We also made the first detailed comparison between experiment and the predictions of continuum theory for granular media (hydrodynamic equations). We found that shock waves easily form in granular flows since the speed of sound waves (pressure fluctuations) in a granular gas is small, typically 10 cm, while flow velocities are easily an order of magnitude larger. Our measurements on vertically oscillating granular layers led to the development of a novel technique for continuously separating particles of different sizes. Our study of craters formed by the impact of a projectile in a granular medium showed, surprisingly, that the time taken for a projectile to come to a rest in the granular layer is independent of the projectile’s impact energy. Another study supported by this grant examined a vertically oscillating layer of a mixture of cornstarch and water. The discovery of stable holes in the mixture was reported widely in the popular press, e.g., Science News [15 May 2004], “Imaging poking a liquid to create holes that persist like the holes in Swiss cheese. Incredible as that might sound, a group of scientists has done it.” Further experiments on glass spheres in an aqueous solution yielded the same holey fluid phenomenon, supporting our conjecture that such holes may occur in dense concentrations of particles in solution in industrial applications.

  2. Effective Reduction of Coulomb Repulsion in Charged Granular Matter

    NASA Astrophysics Data System (ADS)

    Scheffler, T.; Werth, J.; Wolf, D. E.

    2000-04-01

    This paper is an extension to a previous article by Scheffler and Wolfs.6 We study the rate of energy dissipation due to inelastic collisions in a charged granular gas. One observes that the electrostatic repulsion of two particles is effectively reduced by nearest neighbor interactions in a dense granular gas. We study the radial distribution function for dense systems, which leads to a better expression for the reduced energy barrier.

  3. Granular cells in ameloblastoma: An enigma in diagnosis.

    PubMed

    Dave, Aparna; Arora, Manpreet; Shetty, V P; Saluja, Pulin

    2015-01-01

    Ameloblastoma is an epithelial odontogenic tumor exhibiting diverse microscopic pattern that occurs singly or in combination with other patterns. This article describes a case of granular cell ameloblastoma (GCA) involving mandible in a 55-year-old male. The possibility of granular component is there in other odontogenic and nonodontogenic lesions. Sometimes dilemma exists in the diagnosis of such lesions. The purpose of this article is to unveil the hidden characteristics in GCA, which might help in differential diagnosis of GCA. PMID:26752883

  4. Effect of finite particle interaction time in granular systems

    SciTech Connect

    Zhang, D.Z.; Rauenzahn, R.M.

    1998-07-01

    Almost all previously published theoretical papers that propose constitutive relations for granular flows use some form of kinetic theory, which neglects effects of finite particle interaction time and multiparticle interactions. In dense systems, these effects contain essential physics and determine the evolution of the stress system in granular flows. In this paper, the authors shall demonstrate the importance of these effects and study the behavior of the granular stress in a dense system. The particle interaction time is a random variable in a granular system, and they show that its probability distribution obeys an exponential law. The temporal decay of this probability represents the destruction of contacts between particles and is related to the relaxation of the collisional stress in a granular system. By considering the balance between creation and destruction of contacts, they derive a constitutive relation for collisional stress. Depending on the form of the model chosen to approximate forces developed during particle interactions, the constitutive relation can predict either viscoelastic or viscoplastic behavior of the collisional stress. Numerical simulations are performed to verify the theoretical findings and to study further the properties of dense granular systems.

  5. The effectiveness of resistive force theory in granular locomotiona)

    NASA Astrophysics Data System (ADS)

    Zhang, Tingnan; Goldman, Daniel I.

    2014-10-01

    Resistive force theory (RFT) is often used to analyze the movement of microscopic organisms swimming in fluids. In RFT, a body is partitioned into infinitesimal segments, each of which generates thrust and experiences drag. Linear superposition of forces from elements over the body allows prediction of swimming velocities and efficiencies. We show that RFT quantitatively describes the movement of animals and robots that move on and within dry granular media (GM), collections of particles that display solid, fluid, and gas-like features. RFT works well when the GM is slightly polydisperse, and in the "frictional fluid" regime such that frictional forces dominate material inertial forces, and when locomotion can be approximated as confined to a plane. Within a given plane (horizontal or vertical) relationships that govern the force versus orientation of an elemental intruder are functionally independent of the granular medium. We use the RFT to explain features of locomotion on and within granular media including kinematic and muscle activation patterns during sand-swimming by a sandfish lizard and a shovel-nosed snake, optimal movement patterns of a Purcell 3-link sand-swimming robot revealed by a geometric mechanics approach, and legged locomotion of small robots on the surface of GM. We close by discussing situations to which granular RFT has not yet been applied (such as inclined granular surfaces), and the advances in the physics of granular media needed to apply RFT in such situations.

  6. Continuum modeling of dense granular flow down heaps

    NASA Astrophysics Data System (ADS)

    Henann, David; Liu, Daren

    Dense, dry granular flows display many manifestations of grain-size dependence, or nonlocality, in which the finite-size of grains has an observable impact on flow phenomenology. Such behaviors make the formulation of an accurate continuum model for dense granular flow particularly difficult, since local continuum models are not equipped to describe size-effects. One example of grain-size dependence is seen when avalanches occur on a granular heap - a situation which is frequently encountered in industry, as in rotating drums, as well as in nature, such as in landslides. In this case, flow separates into a thin, quickly flowing surface layer and a slowly creeping bulk. While existing local granular flow models are capable of capturing aspects of the flowing surface layer, they fail to even predict the existence of creeping flow beneath, much less being able to quantitatively describe the flow fields. Recently, we have proposed a new, scale-dependent continuum model - the nonlocal granular fluidity (NGF) model - that successfully predicted steady, slow granular flow fields, including grain-size-dependent shear-band widths in a variety of flow configurations. In this talk, we extend our model to the rapid flow regime and show that the model is capable of quantitatively predicting all aspects of gravity-driven heap flow. In particular, the model predicts the coexistence of a rapidly flowing, rate-dependent top surface layer and a rate-independent, slowly creeping bulk - a feature which is beyond local continuum approaches.

  7. Numerical tests of constitutive laws for dense granular flows.

    PubMed

    Lois, Gregg; Lemaître, Anaël; Carlson, Jean M

    2005-11-01

    We numerically and theoretically study the macroscopic properties of dense, sheared granular materials. In this process we first consider an invariance in Newton's equations, explain how it leads to Bagnold's scaling, and discuss how it relates to the dynamics of granular temperature. Next we implement numerical simulations of granular materials in two different geometries--simple shear and flow down an incline--and show that measurements can be extrapolated from one geometry to the other. Then we observe nonaffine rearrangements of clusters of grains in response to shear strain and show that fundamental observations, which served as a basis for the shear transformation zone (STZ) theory of amorphous solids [M. L. Falk and J. S. Langer, Phys. Rev. E. 57, 7192 (1998); M.R.S. Bull 25, 40 (2000)], can be reproduced in granular materials. Finally we present constitutive equations for granular materials as proposed by Lemaître [Phys. Rev. Lett. 89, 064303 (2002)], based on the dynamics of granular temperature and STZ theory, and show that they match remarkably well with our numerical data from both geometries. PMID:16383599

  8. Can one ``Hear'' the aggregation state of a granular system?

    NASA Astrophysics Data System (ADS)

    Kruelle, Christof A.; Sánchez, Almudena García

    2013-06-01

    If an ensemble of macroscopic particles is mechanically agitated the constant energy input is dissipated into the system by multiple inelastic collisions. As a result, the granular material can exhibit, depending on the magnitude of agitation, several physical states - like a gaseous phase for high energy input or a condensed state for low agitation. Here we introduce a new method for quantifying the acoustical response of the granular system. Our experimental system consists of a monodisperse packing of glass beads with a free upper surface, which is confined inside a cylindrical container. An electro-mechanical shaker exerts a sinusoidal vertical vibration at normalized accelerations well above the fluidization threshold for a monolayer of particles. By increasing the number of beads the granular gas suddenly collapses if a critical threshold is exceeded. The transition can be detected easily with a microphone connected to the soundcard of a PC. From the recorded audio track a FFT is calculated in real-time. Depending on either the number of particles at a fixed acceleration or the amount of energy input for a given number of particles, the resulting rattling noise exhibits a power spectrum with either the dominating (shaker) frequency plus higher harmonics for a granular crystal or a high-frequency broad-band noise for a granular gas, respectively. Our new method demonstrates that it is possible to quantify analytically the subjective audio impressions of a careful listener and thus to distinguish easily between different aggregation states of an excited granular system.

  9. Erosion processes in granular flows: insights from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Farin, Maxime; Mangeney, Anne; Roche, Olivier

    2013-04-01

    Experimental granular column collapse were conducted over an inclined channel covered by an erodible bed of granular material in order to reproduce at laboratory scale erosion processes of natural flows propagating over deposits formed by earlier events. The studied control parameters were the slope angle, the aspect ratio (i.e. height over length), the volume and the shape of the granular column released, and the thickness and compaction of the erodible bed. The results show that erosion processes affect the flow runout distance over a critical slope angle ?c that depends on the column volume, aspect ratio, and shape. For slope higher than ?c, the granular avalanche excavates the erodible layer immediately at the flow front, behind which waves traveling downstream are observed and help entraining grains from the erodible bed. Erosion efficiency (i.e. maximal depth and duration of excavation, waves dimensions) is shown to increase as the slope angle and the column's volume increase. It is also dependent on the aspect ratio and on the nature of the erodible bed: the maximal excavation depth and the duration of the excavation decrease as the degree of compaction of the erodible granular bed increases. Erosion processes notably increase granular flows runout distance at inclinations close to the repose angle of the grains, in particular for columns of small aspect ratio. We demonstrate, however, that the flow runout distance observed on an erodible bed cannot be reproduced on a rough bed by simply adding the entrained volume of erodible bed to the initial column volume.

  10. Different Effects of Roughness (Granularity) and Hydrophobicity

    NASA Astrophysics Data System (ADS)

    Shirtcliffe, Neil; McHale, Glen; Hamlett, Christopher; Newton, Michael

    2010-05-01

    With thanks to Stefan Doerr and Jorge Mataix-Solera for their invitation Superhydrophobicity is an interesting effect that appears to be simple on the outset; increased surface area from roughness increases interfacial area and therefore energy loss or gain. More extreme roughness prevents total wetting, resulting in gas pockets present at the surface and a drastic change in the properties of the system. Increases in complexity of the system, by adding porosity (granularity), allowing the structures to move, varying the shape of the roughness or the composition of the liquid used often has unexpected effects. Here we will consider a few of these related to complex topography. Overhanging features are commonly used in test samples as they perform better in some tests than simple roughness. It has been shown to be a prerequisite for superoleophobic surfaces as it allows liquids to be suspended for contact angles considerably below 90°. It also allows trapping of gas in lower layers even if the first layer is flooded. This is important in soils as a fixed bed of granules behaves just like a surface with overhanging roughness. Using simple geometry it is possible to predict at what contact angle penetration will occur. Plants have some structured superhydrophobic surfaces and we have shown that some use them in conjunction with other structured surfaces to control water flows. This allows some plants to survive in difficult environments and shows us how subtly different structures interact completely differently with water. Long fibres can either cause water droplets to roll over a plant surface or halt it in its tracks. Implications of this in soils include predicting when particles will adhere more strongly to water drops and why organic fibrous material may play a greater role in the behaviour of water in soils than may be expected from the amount present. The garden snail uses a biosurfactant that is very effective at wetting surfaces and can crawl over most

  11. Simulating granular materials by energy minimization

    NASA Astrophysics Data System (ADS)

    Krijgsman, D.; Luding, S.

    2016-03-01

    Discrete element methods are extremely helpful in understanding the complex behaviors of granular media, as they give valuable insight into all internal variables of the system. In this paper, a novel discrete element method for performing simulations of granular media is presented, based on the minimization of the potential energy in the system. Contrary to most discrete element methods (i.e., soft-particle method, event-driven method, and non-smooth contact dynamics), the system does not evolve by (approximately) integrating Newtons equations of motion in time, but rather by searching for mechanical equilibrium solutions for the positions of all particles in the system, which is mathematically equivalent to locally minimizing the potential energy. The new method allows for the rapid creation of jammed initial conditions (to be used for further studies) and for the simulation of quasi-static deformation problems. The major advantage of the new method is that it allows for truly static deformations. The system does not evolve with time, but rather with the externally applied strain or load, so that there is no kinetic energy in the system, in contrast to other quasi-static methods. The performance of the algorithm for both types of applications of the method is tested. Therefore we look at the required number of iterations, for the system to converge to a stable solution. For each single iteration, the required computational effort scales linearly with the number of particles. During the process of creating initial conditions, the required number of iterations for two-dimensional systems scales with the square root of the number of particles in the system. The required number of iterations increases for systems closer to the jamming packing fraction. For a quasi-static pure shear deformation simulation, the results of the new method are validated by regular soft-particle dynamics simulations. The energy minimization algorithm is able to capture the evolution of the

  12. Gluon bremstrahlung effects in large P/sub perpendicular/ hadron-hadron scattering

    SciTech Connect

    Fox, G.C.; Kelly, R.L.

    1982-02-01

    We consider effects of parton (primarily gluon) bremstrahlung in the initial and final states of high transverse momentum hadron-hadron scattering. Monte Carlo calculations based on conventional QCD parton branching and scattering processes are presented. The calculations are carried only to the parton level in the final state. We apply the model to the Drell-Yan process and to high transverse momentum hadron-hadron scattering triggered with a large aperture calorimeter. We show that the latter triggers are biased in that they select events with unusually large bremstrahlung effects. We suggest that this trigger bias explains the large cross section and non-coplanar events observed in the NA5 experiment at the SPS.

  13. Future hadron physics facilities at Fermilab

    SciTech Connect

    Appel, Jeffrey A.; /Fermilab

    2004-12-01

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

  14. The Pion cloud: Insights into hadron structure

    SciTech Connect

    A.W. Thomas

    2007-11-01

    Modern nuclear theory presents a fascinating study in contrasting approaches to the structure of hadrons and nuclei. Nowhere is this more apparent than in the treatment of the pion cloud. As this discussion really begins with Yukawa, it is entirely appropriate that this invited lecture at the Yukawa Institute in Kyoto should deal with the issue.

  15. Production of strange particles in hadronization processes

    SciTech Connect

    Hofmann, W.

    1987-08-01

    Strange particles provide an important tool for the study of the color confinement mechanisms involved in hadronization processes. We review data on inclusive strange-particle production and on correlations between strange particles in high-energy reactions, and discuss phenomenological models for parton fragmentation. 58 refs., 24 figs.

  16. Scaling violation in hadron-nucleus interaction

    NASA Technical Reports Server (NTRS)

    Garsevanishvili, L. P.; Ladaria, N. K.; Tsomaya, P. V.; Sherer, N. I.; Shabelski, Y. M.; Verbetski, Y. G.; Kotlyarevski, D. M.; Tatalashvili, N. G.; Stemanetyan, G. Z.

    1985-01-01

    The scaling violation within the pionization region in the energy range of 0.2 to 2.0 TeV is shown on the basis of the analysis of angular characteristics in the interactions of the cosmic radiation hadrons with the nuclei of various substances (CH2, Al, Cu, Pb).

  17. Light-Front Dynamics in Hadron Physics

    NASA Astrophysics Data System (ADS)

    Ji, Chueng-Ryong; Bakker, Bernard L. G.; Choi, Ho-Meoyng

    2013-03-01

    Light-front dynamics(LFD) plays an important role in the analyses of relativistic few-body systems. As evidenced from the recent studies of generalized parton distributions (GPDs) in hadron physics, a natural framework for a detailed study of hadron structures is LFD due to its direct application in Minkowski space as well as its distinct feature of accounting for the vacuum fluctuations in quantum field theories. In the last few years, however, it has been emphasized that treacherous points such as LF singularities and zero-modes should be taken into account for successful LFD applications to hadron phenomenology. In this paper, we discuss a typical example of the contemporary relativistic hadron physics in which the fundamental issues should be taken into account for the successful application of LFD. In particular, we focus on the kinematic issue of GPDs in deeply virtual Compton scattering (DVCS). Although this fundamental issue has been glossed over in the literature, it must be taken care of for the correct analysis of DVCS data.

  18. Pion double charge exchange and hadron dynamics

    SciTech Connect

    Johnson, M.B.

    1991-01-01

    This paper will review theoretical results to show how pion double charge exchange is contributing to our understanding of hadron dynamics in nuclei. The exploitation of the nucleus as a filter is shown to be essential in facilitating the comparison between theory and experiment. 23 refs., 3 figs., 2 tabs.

  19. Recent measurements of the B hadron lifetime

    SciTech Connect

    Ong, R.A.

    1987-12-01

    Recent measurements of the B hadron lifetime from PEP and PETRA experiments are presented. These measurements firmly establish that the B lifetime is long (approx.1 psec), implying that the mixing between the third generation of quarks and the lighter quarks is much weaker that the mixing between the first two generations.

  20. Ratios of heavy hadron semileptonic decay rates

    SciTech Connect

    Gronau, Michael; Rosner, Jonathan L.

    2011-02-01

    Ratios of charmed meson and baryon semileptonic decay rates appear to be satisfactorily described by considering only the lowest-lying (S-wave) hadronic final states and assuming the kinematic factor describing phase space suppression is the same as that for free quarks. For example, the rate for D{sub s} semileptonic decay is known to be (17.0{+-}5.3)% lower than those for D{sup 0} or D{sup +}, and the model accounts for this difference. When applied to hadrons containing b quarks, this method implies that the B{sub s} semileptonic decay rate is about 1% higher than that of the nonstrange B mesons. This small difference thus suggests surprisingly good local quark-hadron duality for B semileptonic decays, complementing the expectation based on inclusive quark-hadron duality that these differences in rates should not exceed a few tenths of a percent. For {Lambda}{sub b} semileptonic decay, however, the inclusive rate is predicted to be about 13% greater than that of the nonstrange B mesons. This value, representing a considerable departure from a calculation using a heavy-quark expansion, is close to the corresponding experimental ratio {Gamma}({Lambda}{sub b})/{Gamma}(B)=1.13{+-}0.03 of total decay rates.