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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 Showers in a Highly Granular Imaging Calorimeter

    NASA Astrophysics Data System (ADS)

    Kaplan, A.; The Calice Collaboration

    The CALICE collaboration develops highly granular calorimeter prototypes to evaluate technologies for experiments at a future lepton collider. The analogue hadronic calorimeter prototype consists of steel absorber plates interleaved with 38 active plastic scintillator layers which are sub-divided into small tiles. In total 7608 tiles are read out individually via embedded Silicon Photomultipliers. The prototype is one of the first large scale applications of these novel and very promising miniature photodetectors. Since 2006, the calorimeter has been operated in combined test beam setups at DESY, CERN and FNAL. The high-resolution 3D image data with analogue energy information are used to study properties and composition of hadronic showers at a new level of detail. This helps to constrain hadronic shower models through comparisons with model calculations. The spatial shower development and the substructure of the showers, compared to a variety of different Geant 4 shower models including decompositions into individual shower components are presented. Aspects of the energy reconstruction of hadronic showers, such as Particle Flow, are discussed.

  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. Energy reconstruction in a highly granularity semi-digital hadronic calorimeter

    SciTech Connect

    Sameh Mannai

    2015-07-01

    A semi-digital hadronic calorimeter using Glass Resistive Plate Chambers (GRPCs) is one of the calorimeters candidates proposed for particle physics experiments at the future electrons collider. It is a high granular calorimeter which is required for application of the particle flow algorithm in order to improve the jet energy resolution as one of the goals of this experiments. We discussed the energy reconstruction, based on digital and semi-Digital methods, to study the effect on the improvement of the single particle energy resolution and the linearity of the detector response. This study was performed with the GEANT4 simulation. Results on the energy resolution and linearity, for negative pions over an energy range from 1 to 100 GeV are presented and compared with different energy reconstruction methods including Artificial Neural Networks. (authors)

  6. The time structure of hadronic showers in highly granular calorimeters with tungsten and steel absorbers

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Blaising, J.-J.; Chefdeville, M.; Drancourt, C.; Gaglione, R.; Geffroy, N.; Karyotakis, Y.; Koletsou, I.; Prast, J.; Vouters, G.; Repond, J.; Schlereth, J.; Xia, L.; Baldolemar, E.; Li, J.; Park, S. T.; Sosebee, M.; White, A. P.; Yu, J.; Eigen, G.; Thomson, M. A.; Ward, D. R.; Benchekroun, D.; Hoummada, A.; Khoulaki, Y.; Apostolakis, J.; Arfaoui, S.; Benoit, M.; Dannheim, D.; Elsener, K.; Folger, G.; Grefe, C.; Ivantchenko, V.; Killenberg, M.; Klempt, W.; van der Kraaij, E.; Linssen, L.; Lucaci-Timoce, A.-I.; Münnich, A.; Poss, S.; Ribon, A.; Roloff, P.; Sailer, A.; Schlatter, D.; Sicking, E.; Strube, J.; Uzhinskiy, V.; Cârloganu, C.; Gay, P.; Manen, S.; Royer, L.; Cornett, U.; David, D.; Ebrahimi, A.; Falley, G.; Feege, N.; Gadow, K.; Göttlicher, P.; Günter, C.; Hartbrich, O.; Hermberg, B.; Karstensen, S.; Krivan, F.; Krüger, K.; Lu, S.; Lutz, B.; Morozov, S.; Morgunov, V.; Neubüser, C.; Reinecke, M.; Sefkow, F.; Smirnov, P.; Terwort, M.; Fagot, A.; Tytgat, M.; Zaganidis, N.; Hostachy, J.-Y.; Morin, L.; Garutti, E.; Laurien, S.; Marchesini, I.; Matysek, M.; Ramilli, M.; Briggl, K.; Eckert, P.; Harion, T.; Schultz-Coulon, H.-Ch; Shen, W.; Stamen, R.; Chang, S.; Khan, A.; Kim, D. H.; Kong, D. J.; Oh, Y. D.; Bilki, B.; Norbeck, E.; Northacker, D.; Onel, Y.; Wilson, G. W.; Kawagoe, K.; Miyazaki, Y.; Sudo, Y.; Ueno, H.; Yoshioka, T.; Dauncey, P. D.; Cortina Gil, E.; Mannai, S.; Baulieu, G.; Calabria, P.; Caponetto, L.; Combaret, C.; Della Negra, R.; Eté, R.; Grenier, G.; Han, R.; Ianigro, J.-C.; Kieffer, R.; Laktineh, I.; Lumb, N.; Mathez, H.; Mirabito, L.; Petrukhin, A.; Steen, A.; Tromeur, W.; Vander Donckt, M.; Zoccarato, Y.; Berenguer Antequera, J.; Calvo Alamillo, E.; Fouz, M.-C.; Puerta-Pelayo, J.; Corriveau, F.; Bobchenko, B.; Chadeeva, M.; Danilov, M.; Epifantsev, A.; Markin, O.; Mizuk, R.; Novikov, E.; Rusinov, V.; Tarkovsky, E.; Kozlov, V.; Soloviev, Y.; Besson, D.; Buzhan, P.; Ilyin, A.; Kantserov, V.; Kaplin, V.; Popova, E.; Tikhomirov, V.; Gabriel, M.; Kiesling, C.; Seidel, K.; Simon, F.; Soldner, C.; Szalay, M.; Tesar, M.; Weuste, L.; Amjad, M. S.; Bonis, J.; Conforti di Lorenzo, S.; Cornebise, P.; Fleury, J.; Frisson, T.; van der Kolk, N.; Richard, F.; Pöschl, R.; Rouëné, J.; Anduze, M.; Balagura, V.; Becheva, E.; Boudry, V.; Brient, J.-C.; Cornat, R.; Frotin, M.; Gastaldi, F.; Guliyev, E.; Haddad, Y.; Magniette, F.; Ruan, M.; Tran, T. H.; Videau, H.; Callier, S.; Dulucq, F.; Martin-Chassard, G.; de la Taille, Ch; Raux, L.; Seguin-Moreau, N.; Zacek, J.; Cvach, J.; Gallus, P.; Havranek, M.; Janata, M.; Kvasnicka, J.; Lednicky, D.; Marcisovsky, M.; Polak, I.; Popule, J.; Tomasek, L.; Tomasek, M.; Ruzicka, P.; Sicho, P.; Smolik, J.; Vrba, V.; Zalesak, J.; Belhorma, B.; Ghazlane, H.; Kotera, K.; Ono, H.; Takeshita, T.; Uozumi, S.; Chai, J. S.; Song, H. S.; Lee, S. H.; Götze, M.; Sauer, J.; Weber, S.; Zeitnitz, C.

    2014-07-01

    The intrinsic time structure of hadronic showers influences the timing capability and the required integration time of hadronic calorimeters in particle physics experiments, and depends on the active medium and on the absorber of the calorimeter. With the CALICE T3B experiment, a setup of 15 small plastic scintillator tiles read out with Silicon Photomultipliers, the time structure of showers is measured on a statistical basis with high spatial and temporal resolution in sampling calorimeters with tungsten and steel absorbers. The results are compared to GEANT4 (version 9.4 patch 03) simulations with different hadronic physics models. These comparisons demonstrate the importance of using high precision treatment of low-energy neutrons for tungsten absorbers, while an overall good agreement between data and simulations for all considered models is observed for steel.

  7. Small pad RPCs as detector for high granularity digital hadron calorimetry

    NASA Astrophysics Data System (ADS)

    Ammosov, V.; Gapienko, V.; Ivanilov, A.; Sefkow, F.; Semak, A.; Sviridov, Yu.; Usenko, E.; Zaets, V.

    2004-11-01

    Requirements for sampling hadron calorimetry with gaseous active medium and digital read-out for a future linear e+e--collider (FLC) are formulated. Monogap glass Resistive Plate Chamber (RPC) prototypes equipped with 1cm2 read-out pads and operated in saturated avalanche and streamer modes are studied as a possible detector for digital hadron calorimetry. Operating characteristics of the prototypes such as induced charges, efficiencies and fired pad multiplicities are measured for different gas mixtures, gas gap widths and anode thicknesses, electronics thresholds, beam incident angle and intensity. Choice of RPC working performance is outlined.

  8. A high-granularity plastic scintillator tile hadronic calorimeter with APD readout for a linear collider detector

    NASA Astrophysics Data System (ADS)

    Andreev, V.; Cvach, J.; Danilov, M.; Devitsin, E.; Dodonov, V.; Eigen, G.; Garutti, E.; Gilitzky, Yu.; Groll, M.; Heuer, R.-D.; Janata, M.; Kacl, I.; Korbel, V.; Kozlov, V.; Meyer, H.; Morgunov, V.; Němeček, S.; Pöschl, R.; Polák, I.; Raspereza, A.; Reiche, S.; Rusinov, V.; Sefkow, F.; Smirnov, P.; Terkulov, A.; Valkár, Š.; Weichert, J.; Zálešák, J.

    2006-08-01

    We report upon the performance of an analog hadron calorimeter prototype, where plastic scintillator tiles are read out with wavelength-shifting fibers coupled to avalanche photodiodes. This prototype configuration has been tested using a positron beam at DESY with energies between 1 and 6 GeV. We present different detector calibration methods, show measurements for noise, linearity, and energy resolution and discuss gain monitoring with an LED system. The results are in good agreement with our simulation studies and previous measurements using silicon photomultiplier readout.

  9. Scintillator-based fast ion loss measurements in the EAST

    NASA Astrophysics Data System (ADS)

    Chang, J. F.; Isobe, M.; Ogawa, K.; Huang, J.; Wu, C. R.; Xu, Z.; Jin, Z.; Lin, S. Y.; Hu, L. Q.

    2016-11-01

    A new scintillator-based fast ion loss detector (FILD) has been installed on Experimental Advanced Superconducting Tokamak (EAST) to investigate the fast ion loss behavior in high performance plasma with neutral beam injection (NBI) and ion cyclotron resonance heating (ICRH). A two dimensional 40 mm × 40 mm scintillator-coated (ZnS:Ag) stainless plate is mounted in the front of the detector, capturing the escaping fast ions. Photons from the scintillator plate are imaged with a Phantom V2010 CCD camera. The lost fast ions can be measured with the pitch angle from 60° to 120° and the gyroradius from 10 mm to 180 mm. This paper will describe the details of FILD diagnostic on EAST and describe preliminary measurements during NBI and ICRH heating.

  10. 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

  11. 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.

  12. Radiation-resistant composite scintillators based on GSO and GPS grains

    NASA Astrophysics Data System (ADS)

    Boyarintsev, A. Yu.; Galunov, N. Z.; Gerasymov, Ia. V.; Karavaeva, N. L.; Krech, A. V.; Levchuk, L. G.; Popov, V. F.; Sidletskiy, O. Ts.; Sorokin, P. V.; Tarasenko, O. A.

    2017-01-01

    The effect of irradiation on the scintillation light output, optical transmittance, and luminescent spectra of composite scintillators based on grains of single crystals Gd2SiO5:Ce (GSO) and Gd2Si2O7:Ce (GPS) is studied. The dielectric gel Sylgard-184 is the base and the binder for the grains inside the composite scintillator. The paper presents and analyzes the results obtained for the scintillators exposed by 10 MeV electrons from the linear electron accelerator at room temperature. The exposure doses D≤250 Mrad. The dose rate is 0.2 or 1500 Mrad/h. The study has shown that the composite scintillators based on the grains of GSO and GPS are radiation-resistant over the range of the irradiation.

  13. Granular Physics

    NASA Astrophysics Data System (ADS)

    Mehta, Anita

    2011-03-01

    1. Introduction; 2. Computer simulation approaches - an overview; 3. Structure of vibrated powders - numerical results; 4. Collective structures in sand - the phenomenon of bridging; 5. On angles of repose: bistability and collapse; 6. Compaction of disordered grains in the jamming limit: sand on random graphs; 7. Shaking a box of sand I - a simple lattice model; 8. Shaking a box of sand II - at the jamming limit, when shape matters!; 9. Avalanches with reorganising grains; 10. From earthquakes to sandpiles - stick-slip motion; 11. Coupled continuum equations: the dynamics of sand-pile surfaces; 12. Theory of rapid granular flows; 13. The thermodynamics of granular materials; 14. Static properties of granular materials; Author index; Subject index; Bibliography.

  14. Granular Physics

    NASA Astrophysics Data System (ADS)

    Mehta, Anita

    2007-06-01

    1. Introduction; 2. Computer simulation approaches - an overview; 3. Structure of vibrated powders - numerical results; 4. Collective structures in sand - the phenomenon of bridging; 5. On angles of repose: bistability and collapse; 6. Compaction of disordered grains in the jamming limit: sand on random graphs; 7. Shaking a box of sand I - a simple lattice model; 8. Shaking a box of sand II - at the jamming limit, when shape matters!; 9. Avalanches with reorganising grains; 10. From earthquakes to sandpiles - stick-slip motion; 11. Coupled continuum equations: the dynamics of sand-pile surfaces; 12. Theory of rapid granular flows; 13. The thermodynamics of granular materials; 14. Static properties of granular materials; Author index; Subject index; Bibliography.

  15. Granular slumps

    NASA Astrophysics Data System (ADS)

    Balmforth, Neil J.; Kerswell, Richard R.

    2002-11-01

    We report an experimental and theoretical study of slumping granular fluids. We use a variety of different materials, and explore how they slump in a chute once a gate holding one side of the material is suddenly released, in a set-up intended to mimic the classical dambreak problem of hydrodynamics. Two widths of the chute are used, one relatively thin, and one relatively thick. After a violent transient in which material rains down ballistically, the granular mass enters a slower phase of evolution in which it slumps towards a final equilibrium state. We compare the predictions of some theoretical models with the shape of the final equilibrium.

  16. 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.

  17. Granular parakeratosis.

    PubMed

    Martín, José M; Pinazo, Isabel; Molina, Inmaculada; Monteagudo, Carlos; Villalón, Guillermo; Jordá, Esperanza

    2008-07-01

    A healthy 62-year-old woman was referred to our dermatology department with a 1-month history of a pruritic axillary eruption. On examination, multiple erythematous and brownish hyperkeratotic papules were seen in both axillae. Some of these lesions coalesced into plaques, with small areas of sparing, and a background erythematous color was also found in the axillary vaults (Fig. 1). There was no involvement of other intertriginous sites and there were no associated systemic symptoms. The patient was not obese. The patient had removed the hair from her axillae with wax 3 weeks before the development of the eruption. Moreover, she had changed her antiperspirant 1 week before the onset of the lesions. A cutaneous biopsy for histologic analysis was performed. Histologically, the stratum corneum was thickened, with persistent nuclei together with countless small basophilic granules. The granular layer was preserved and, in some areas, hypergranulosis was found (Fig. 2). These findings were characteristic of granular parakeratosis. The cutaneous lesions resolved completely after 1 week of treatment with topical betamethasone dipropionate and gentamicin sulfate (twice daily). The patient was urged to discontinue her use of deodorants.

  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. 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.

  20. Hexagonal Uniformly Redundant Arrays (HURAs) for scintillator based coded aperture neutron imaging

    SciTech Connect

    Gamage, K.A.A.; Zhou, Q.

    2015-07-01

    A series of Monte Carlo simulations have been conducted, making use of the EJ-426 neutron scintillator detector, to investigate the potential of using hexagonal uniformly redundant arrays (HURAs) for scintillator based coded aperture neutron imaging. This type of scintillator material has a low sensitivity to gamma rays, therefore, is of particular use in a system with a source that emits both neutrons and gamma rays. The simulations used an AmBe source, neutron images have been produced using different coded-aperture materials (boron- 10, cadmium-113 and gadolinium-157) and location error has also been estimated. In each case the neutron image clearly shows the location of the source with a relatively small location error. Neutron images with high resolution can be easily used to identify and locate nuclear materials precisely in nuclear security and nuclear decommissioning applications. (authors)

  1. Hadron physics

    SciTech Connect

    Bunce, G.

    1984-05-30

    Is all hadronic physics ultimately describable by QCD. Certainly, many disparate phenomena can be understood within the QCD framework. Also certainly, there are important questions which are open, both theoretically (little guidance, as yet) and experimentally, regarding confinement. Are there dibaryons, baryonium, glueballs. In addition, there are experimental results which at present do not have an explanation. This talk, after a short section on QCD successes and difficulties, will emphasize two experimental topics which have recent results - glueball spectroscopy and exclusive reactions at large momentum transfer. Both are experimentally accessible in the AGS/LAMPF II/AGS II/TRIUMF II/SIN II energy domain.

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Particle Deposition in Granular Media

    SciTech Connect

    Tien, C.

    1992-01-01

    Objective is to understand aerosol deposition from gas streams flowing through granular media; this is important to the design of granular filtration systems. The following investigations were carried out: transient behavior of granular filtration of aerosols, and stochastic simulation of aerosol deposition in granular media.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. QCD, hadrons and beyond

    NASA Astrophysics Data System (ADS)

    Nardulli, G.

    2005-04-01

    I give a summary of Section E of the sixth edition of the Conference Quark confinement and the hadron spectrum. Papers were presented on different subjects, from spectroscopy, including pentaquarks and hadron structure, to new physics effects (non commutative field theories, supersymmetry and extra dimensions) and the problem of color confinement, both in ordinary Yang-Mills models and in supersymmetric Yang-Mills.

  14. Granular computing: perspectives and challenges.

    PubMed

    Yao, JingTao; Vasilakos, Athanasios V; Pedrycz, Witold

    2013-12-01

    Granular computing, as a new and rapidly growing paradigm of information processing, has attracted many researchers and practitioners. Granular computing is an umbrella term to cover any theories, methodologies, techniques, and tools that make use of information granules in complex problem solving. The aim of this paper is to review foundations and schools of research and to elaborate on current developments in granular computing research. We first review some basic notions of granular computing. Classification and descriptions of various schools of research in granular computing are given. We also present and identify some research directions in granular computing.

  15. Fluctuations in granular materials

    NASA Astrophysics Data System (ADS)

    Behringer, R. P.

    The intent of this work is to provide an overview of granular materials, with a particular focus on the dense granular states. The first part consists of a broad overview of granular properties. Then, there is an exploration of a range of phenomena that are illustrated through a series of experiments. The work presented here has benefitted from a number of collaborators, including in particular Eric Clément, Junfei Geng, Daniel Howell, Stefan Luding, Trushant Majmudar, Corey O'Hern, Guillaume Reydellet Matthias Sperl, Brian Utter and Peidong Yu who are represented by results that are presented in this work. Support has been provided by the US National Science Foundation, by NASA, and by ARO.

  16. 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.

  17. Study of the performance of a semi-digital hadronic calorimeter using Monte Carlo techniques

    NASA Astrophysics Data System (ADS)

    Elmahroug, Y.; Tellili, B.; Souga, C.

    2014-04-01

    The Particle Flow Algorithm is one of the main concepts that will be used to measure the energies of hadronic jets at a future International Linear Collider. This method requires a highly granular hadronic calorimeter to measure the energy of jets with a good precision. The Semi-Digital Hadronic Calorimeter using glass resistive plate chambers as sensitive medium is one of the hadronic calorimeters which is used in conjunction with the particle flow method. In this paper, the performance of Semi-Digital Hadronic Calorimeter using glass resistive plate chambers as active elements has been studied by using the GEANT4 simulations. Its main operational characteristics such as mean response and energy resolution have been examined.

  18. Axillary granular parakeratosis.

    PubMed

    Kossard, S; White, A

    1998-08-01

    A 54-year-old woman had a 3 year history of a recurrent bilateral axillary rash during the summer months. Both axillae showed hyperkeratotic, fissured and cobblestone plaques. Skin biopsy showed the histology previously defined as axillary granular parakeratosis. This finding may indeed represent an unusual contact reaction to anti-perspirants interfering with epidermal keratinization.

  19. Radiobiology of Hadrons

    SciTech Connect

    Streit-Bianchi, Marilena

    2008-08-11

    Radiobiological studies of hadrons beams are essential for optimizing tumour treatments. Whit hadrons when clinical facilities are running radiobiological studies are also done to ensure beam optimization and quality control as well as for the understanding of tumour and normal tissue reactions and late effects. Beam characteristic determinations nowadays are carried out according to well established radiobiological standard parameters and using well established biological reference systems. Some of the most recent studies on the topic are reported here.

  20. Radiobiology of Hadrons

    NASA Astrophysics Data System (ADS)

    Streit-Bianchi, Marilena

    2008-08-01

    Radiobiological studies of hadrons beams are essential for optimizing tumour treatments. Whit hadrons when clinical facilities are running radiobiological studies are also done to ensure beam optimization and quality control as well as for the understanding of tumour and normal tissue reactions and late effects. Beam characteristic determinations nowadays are carried out according to well established radiobiological standard parameters and using well established biological reference systems. Some of the most recent studies on the topic are reported here.

  1. Holography inspired stringy hadrons

    NASA Astrophysics Data System (ADS)

    Sonnenschein, Jacob

    2017-01-01

    Holography inspired stringy hadrons (HISH) is a set of models that describe hadrons: mesons, baryons and glueballs as strings in flat four dimensional space-time. The models are based on a "map" from stringy hadrons of holographic confining backgrounds. In this note we review the "derivation" of the models. We start with a brief reminder of the passage from the AdS5 ×S5 string theory to certain flavored confining holographic models. We then describe the string configurations in holographic backgrounds that correspond to a Wilson line, a meson, a baryon and a glueball. The key ingredients of the four dimensional picture of hadrons are the "string endpoint mass" and the "baryonic string vertex". We determine the classical trajectories of the HISH. We review the current understanding of the quantization of the hadronic strings. We end with a summary of the comparison of the outcome of the HISH models with the PDG data about mesons and baryons. We extract the values of the tension, masses and intercepts from best fits, write down certain predictions for higher excited hadrons and present attempts to identify glueballs.

  2. 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)].

  3. Focus on granular segregation

    NASA Astrophysics Data System (ADS)

    Daniels, Karen E.; Schröter, Matthias

    2013-03-01

    Ordinary fluids mix themselves through thermal motions, or can be even more efficiently mixed by stirring. In contrast, granular materials such as sand often unmix when they are stirred, shaken or sheared. This granular segregation is both a practical means to separate materials in industry, and a persistent challenge to uniformly mixing them. While segregation phenomena are ubiquitous, a large number of different mechanisms have been identified and the underlying physics remains the subject of much inquiry. Particle size, shape, density and even surface roughness can play significant roles. The aim of this focus issue is to provide a snapshot of the current state of the science, covering a wide range of packing densities and driving mechanisms, from thermal-like dilute systems to dense flows.

  4. Hadronization of partons

    SciTech Connect

    Albino, S.

    2010-07-15

    The description of inclusive production of single unpolarized light hadrons using fragmentation functions in the framework of the factorization theorem is reviewed. The factorization of observables into perturbatively calculable quantities and these universal fragmentation functions are summarized and some improvements beyond the standard fixed order approach are discussed. The extraction of fragmentation functions for light charged ({pi}{sup {+-}}, K{sup {+-}}, and p/p) and neutral (K{sub S}{sup 0} and {Lambda}/{Lambda}) hadrons using these theoretical tools is discussed through global fits to experimental data from reactions at various colliders, in particular from accurate e{sup +}e{sup -} reactions at the Large Electron-Position Collider (LEP), and the subsequent successful predictions of other experimental data, such as data gathered at Hadron Electron Ring Accelerator (HERA), the Tevatron, and the Relativistic Heavy Ion Collider (RHIC), from these fitted fragmentation functions as allowed by factorization universality. These global fits also impose competitive constraints on {alpha}{sub s}(M{sub Z}). Emphasis is placed on the need for accurate data from pp(p) and ep reactions in which the hadron species is identified in order to constrain the separate fragmentation functions of the gluon and each quark flavor for each hadron species.

  5. Granular Crater Formation

    NASA Astrophysics Data System (ADS)

    Clark, Abe; Behringer, Robert; Brandenburg, John

    2009-11-01

    This project characterizes crater formation in a granular material by a jet of gas impinging on a granular material, such as a retro-rocket landing on the moon. We have constructed a 2D model of a planetary surface, which consists of a thin, clear box partially filled with granular materials (sand, lunar and Mars simulants...). A metal pipe connected to a tank of nitrogen gas via a solenoid valve is inserted into the top of the box to model the rocket. The results are recorded using high-speed video. We process these images and videos in order to test existing models and develop new ones for describing crater formation. A similar set-up has been used by Metzger et al.footnotetextP. T. Metzger et al. Journal of Aerospace Engineering (2009) We find that the long-time shape of the crater is consistent with a predicted catenary shape (Brandenburg). The depth and width of the crater both evolve logarithmically in time, suggesting an analogy to a description in terms of an activated process: dD/dt = A (-aD) (D is the crater depth, a and A constants). This model provides a useful context to understand the role of the jet speed, as characterized by the pressure used to drive the flow. The box width also plays an important role in setting the width of the crater.

  6. Impact on Granular Beds

    NASA Astrophysics Data System (ADS)

    van der Meer, Devaraj

    2017-01-01

    The impact of an object on a granular solid is an ubiquitous phenomenon in nature, the scale of which ranges from the impact of a raindrop onto sand all the way to that of a large asteroid on a planet. Despite the obvious relevance of these impact events, the study of the underlying physics mechanisms that guide them is relatively young, with most work concentrated in the past decade. Upon impact, an object starts to interact with a granular bed and experiences a drag force from the sand. This ultimately leads to phenomena such as crater formation and the creation of a transient cavity that upon collapse may cause a jet to appear from above the surface of the sand. This review provides an overview of research that targets these phenomena, from the perspective of the analogous but markedly different impact of an object on a liquid. It successively addresses the drag an object experiences inside a granular bed, the expansion and collapse of the cavity created by the object leading to the formation of a jet, and the remarkable role played by the air that resides within the pores between the grains.

  7. 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.

  8. Plastic Deformation of Granular Materials

    DTIC Science & Technology

    1993-01-25

    discontinuities. These result will be important in our granular flow work, when considering viscoplastic constitutive relations (i.e. relaxation systems...5 CUNDN( NUMRES Plastic Deformation of Granular Materials (U) 61102F 6. AUTHOR(S) 2304/A4 Dr. E. Bruce Pitman 7 PERFORMING ORGANIZATION NA .h • 8...lose hyperbolicity. 98 3 81 061! SUBJECT TERMS 15. NUMBER OF PAGES granular material ; plastic deformation; hyperbolic 12 equations 16. PRICE CODE 17

  9. 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.

  10. 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.

  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. 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.

  14. Elastic Granular Flows

    NASA Astrophysics Data System (ADS)

    Campbell, Charles

    2006-03-01

    There is no fundamental understanding of the mechanics of granular solids. Partially this is because granular flows have historically been divided into two very distinct flow regimes, (1) the slow, quasistatic regime, in which the bulk friction coefficient is taken to be a material constant, and (2) the fast, rapid-flow regime, where the particles interact collisionally. But slow hopper flow simulations indicate that the bulk friction coefficient is not a constant. Rapidly moving large scale landslide simulations never entered the collisional regime and operate in a separate intermediate flow regime. In other words, most realistic granular flows are not described by either the quasistatic or rapid flow models and it is high time that the field look beyond those early models. This talk will discuss computer simulation studies that draw out the entire flowmap of shearing granular materials, spanning the quasistatic, rapid and the intermediate regimes. The key was to include the elastic properties of the solid material in the set of rheological parameters; in effect, this puts solid properties back into the rheology of granular solids. The solid properties were previously unnecessary in the plasticity and kinetic theory formalisms that respectively form the foundations of the quasistatic and rapid-flow theories. Granular flows can now be divided into two broad categories, the Elastic Regimes, in which the particles are locked in force chains and interact elastically over long duration contact with their neighbors and the Inertial regimes, where the particles have broken free of the force chains. The Elastic regimes can be further subdivided into the Elastic-Quasistatic regime (the old quasistatic regime) and the Elastic-Inertial regime. The Elastic-Inertial regime is the ``new'' regime observed in the landslide simulations, in which the inertially induced stresses are significant compared to the elastically induced stresses. The Inertial regime can also be sub

  15. Sinking a Granular Raft

    NASA Astrophysics Data System (ADS)

    Protière, Suzie; Josserand, Christophe; Aristoff, Jeffrey M.; Stone, Howard A.; Abkarian, Manouk

    2017-03-01

    We report experiments that yield new insights on the behavior of granular rafts at an oil-water interface. We show that these particle aggregates can float or sink depending on dimensionless parameters taking into account the particle densities and size and the densities of the two fluids. We characterize the raft shape and stability and propose a model to predict its shape and maximum length to remain afloat. Finally we find that wrinkles and folds appear along the raft due to compression by its own weight, which can trigger destabilization. These features are characteristics of an elastic instability, which we discuss, including the limitations of our model.

  16. Labyrinthine granular landscapes.

    PubMed

    Caps, H; Vandewalle, N

    2001-11-01

    We have numerically studied a model of granular landscape eroded by wind. We show the appearance of labyrinthic patterns when the wind orientation turns by 90 degrees. The occurrence of such structures is discussed. Moreover, we introduce the density n(k) of "defects" as the dynamic parameter governing the landscape evolution. A power-law behavior of n(k) is found as a function of time. In the case of wind variations, the exponent (drastically) shifts from two to one. The presence of two asymptotic values of n(k) implies the irreversibility of the labyrinthic formation process.

  17. 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.

  18. 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.

  19. Calibration Studies and the Investigation of Track Segments within Showers with an Imaging Hadronic Calorimeter

    NASA Astrophysics Data System (ADS)

    Lu, Shaojun

    2010-04-01

    The CALICE collaboration has constructed a highly granular hadronic sampling calorimeter prototype with small scintillator tiles individually read out by silicon photomultipliers (SiPM) to evaluate technologies for the ILC. The imaging capability of the detector allows detailed studies of the substructure of hadronic events, such as the identification of minimum ionizing track segments within the hadronic shower. These track segments are of high quality, so that they can be used for calibration, as an additional tool to Muons and to the built-in LED system used to monitor the SiPMs. These track segments also help to constrain hadronic shower models used in Geant4. Detailed MC studies with a realistic model of an ILC detector were performed to study the calibration requirements of a complete calorimeter system. The calibration strategy was tested on real data by transporting calibration constants from a Fermilab beam test to data recorded at CERN under different conditions.

  20. Granular cell tumor of trachea.

    PubMed

    Bekteshi, Edgar; Toth, Jennifer W; Benninghoff, Michael G; Kang, Jason; Betancourt, Manuel

    2009-01-01

    Granular cell tumors of the tracheobronchial tree are rare benign lesions of neurogenic origin. These benign tumors mostly involve the skin, oral cavity, or esophagus. There is no consensus regarding treatment of granular cell tumors. Treatment varies from simple observation to different bronchoscopic interventions, such as laser therapy or fulguration to surgical resection.

  1. 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.

  2. Spreading of a granular droplet

    NASA Astrophysics Data System (ADS)

    Clement, Eric; Sanchez, Ivan; Raynaud, Franck; Lanuza, Jose; Andreotti, Bruno; Aranson, Igor

    2008-03-01

    The influence of controlled vibrations on the granular rheology is investigated in a specifically designed experiment in which a granular film spreads under the action of horizontal vibrations. A nonlinear diffusion equation is derived theoretically that describes the evolution of the deposit shape. A self-similar parabolic shape (the``granular droplet'') and a spreading dynamics are predicted that both agree quantitatively with the experimental results. The theoretical analysis is used to extract effective friction coefficients between the base and the granular layer under sustained and controlled vibrations. A shear thickening regime characteristic of dense granular flows is evidenced at low vibration energy, both for glass beads and natural sand. Conversely, shear thinning is observed at high agitation.

  3. Spreading of a granular droplet

    NASA Astrophysics Data System (ADS)

    Sánchez, Iván; Raynaud, Franck; Lanuza, José; Andreotti, Bruno; Clément, Eric; Aranson, Igor S.

    2007-12-01

    The influence of controlled vibrations on the granular rheology is investigated in a specifically designed experiment in which a granular film spreads under the action of horizontal vibrations. A nonlinear diffusion equation is derived theoretically that describes the evolution of the deposit shape. A self-similar parabolic shape (the“granular droplet”) and a spreading dynamics are predicted that both agree quantitatively with the experimental results. The theoretical analysis is used to extract effective friction coefficients between the base and the granular layer under sustained and controlled vibrations. A shear thickening regime characteristic of dense granular flows is evidenced at low vibration energy, both for glass beads and natural sand. Conversely, shear thinning is observed at high agitation.

  4. Heterogeneities in granular dynamics

    PubMed Central

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

    2008-01-01

    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

  5. Jamming in granular materials

    NASA Astrophysics Data System (ADS)

    Behringer, Robert P.

    2015-01-01

    Granular materials are one of a class of materials which undergo a transition from mechanically unstable to mechanically stable states as key system parameters change. Pioneering work by Liu and Nagel and O'Hern et al. focused on models consisting of frictionless grains. In this case, density, commonly expressed in terms of the packing fraction, ϕ, is of particular importance. For instance, O'Hern et al. found that there is a minimum ϕ =ϕJ, such that below this value there are no jammed states, and that above this value, all stress-isotropic states are jammed. Recently, simulations and experiments have explored the case of grains with friction. This case is more subtle, and ϕ does not play such a simple role. Recently, several experiments have shown that there exists a range of relatively low ϕ's such that at the same ϕ it is possible to have jammed, unjammed, and fragile states in the sense of Cates et al. This review discusses some of this recent work, and contrasts the cases of jamming for frictionless and frictional granular systems.

  6. 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.

  7. Particle Deposition in Granular Media. Final report

    SciTech Connect

    Tien, C.

    1992-12-31

    Objective is to understand aerosol deposition from gas streams flowing through granular media; this is important to the design of granular filtration systems. The following investigations were carried out: transient behavior of granular filtration of aerosols, and stochastic simulation of aerosol deposition in granular media.

  8. Pattern formation in granular and granular-fluid flows

    NASA Astrophysics Data System (ADS)

    Duong, Nhat-Hang P.

    Particles and suspensions of particles in fluids are regularly used in many engineering disciplines such as catalysis and reaction engineering, environmental engineering, pharmaceutical engineering, etc. A few issues that are commonly encountered include ensuring homogeneity in pharmaceutical suspensions, predicting particle transport in atmospheric and effluent streams, and manufacturing uniform composite materials. Yet the fundamental study of particle motions in granular media or in highly concentrated granular suspensions has received little attention. Relevant issues of research interest include development of adaptive models that permit wide ranges of particle concentrations, improvement of analyses that allow physical interpretation of particle motions in any medium, of scales ranging from particle size to system size, and accurate validation of theoretical with experimental data. Given the above shortcomings, this dissertation will focus on investigating basic transport behavior of particles in fluids and developing predictive models for granular media and granular suspensions. Emphasis will be given to combining experiments with computations through examples of pattern forming phenomena in a granular medium and a dense granular-fluid system. The background motivation and the objectives of this dissertation are stated in the opening chapter 1. The next three chapters address these objectives in detail. First, chapter 2 presents experimental evidence, descriptions, and characteristics of novel patterns in a dense granular suspension. This is followed by chapter 3 in which a mean-field continuum model is derived to further elucidate the reported patterning phenomena. Chapter 4 uncovers several novel granular patterns experimentally and is concluded with a coarse-grained phenomenological model for granular surface flows. Lastly, chapter 5 closes the dissertation with conclusions and possible future directions. This work provides additional understanding and

  9. 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.

  10. Granularity analysis for mathematical proofs.

    PubMed

    Schiller, Marvin R G

    2013-04-01

    Mathematical proofs generally allow for various levels of detail and conciseness, such that they can be adapted for a particular audience or purpose. Using automated reasoning approaches for teaching proof construction in mathematics presupposes that the step size of proofs in such a system is appropriate within the teaching context. This work proposes a framework that supports the granularity analysis of mathematical proofs, to be used in the automated assessment of students' proof attempts and for the presentation of hints and solutions at a suitable pace. Models for granularity are represented by classifiers, which can be generated by hand or inferred from a corpus of sample judgments via machine-learning techniques. This latter procedure is studied by modeling granularity judgments from four experts. The results provide support for the granularity of assertion-level proofs but also illustrate a degree of subjectivity in assessing step size.

  11. Physics of very high energy hadron-hadron colliders

    SciTech Connect

    Hinchliffe, I.

    1986-09-01

    A review is given of the physics accessible at a very high energy hadron-hadron collider. Emphasis is placed on the reliability of the predicted rates, and upon the energy and luminosity required to explore new physics options. 38 refs., 19 figs.

  12. 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.

  13. 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.

  14. Hadronic laws from QCD

    NASA Astrophysics Data System (ADS)

    Cahill, R. T.

    1992-06-01

    A review is given of progress in deriving the effective action for hadronic physics, S[π, ϱ, ω,.., overlineN, N,..] , from the fundamental defining action of QCD, S[ overlineq, q, A μa] . This is a problem in quantum field theory and the most success so far has been achieved using functional integral calculus (FIC) techniques. This formulates the problem as an exercise in changing the variables of integration in the functional integrals, from those of the quark and gluon fields to those of the (bare) meson and baryon fields. The appropriate variables are determined by the dynamics of QCD, and the final hadronic variables (essentially the 'normal modes' of QCD) are local fields describing the 'centre-of-mass' motion of extended bound states of quarks. The quarks are extensively dressed by the gluons, and the detailed aspects of the hidden chiral symmetry emerge naturally from the formalism. Particular attention is given to covariant integral equations which determine bare nucleon structure (i.e. in the quenched approximation). These equations, which arise from the closed double-helix diagrams of the FIC analysis, describe the baryons in terms of quark-diquark structure, in the form of Faddeev equations. This hadronisation of QCD also generates the dressing of these baryons by the pions, and the non-local πNN coupling.

  15. 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.

  16. Simulations of Granular Media

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.; Müller, M.

    For the last ten years there has been an enormous progress in the simulation of granular media like sand or powders. These simulations consist in simulating trajectories of each particle individually. Essentially one has to solve the Newton's equations including the effects of Coulomb friction and the physics occuring at a collision. But the details of the trajectories are not important for the collective behaviour. Therefore simplifications are introduced on the smallest scales. I will introduce various methods like molecular dynamics that are used to simulate large amounts of particles (over 109). Some of these medhods are based on the exploitation of parallelisation and metacomputing. Other approaches are more stochastic (DSMC Direct Simulation Monte Carlo) which simplify the calculation of collisions, positions and collision times. Very successful has been also the use of cellular automata which have been able to predict details such as the logarithmic tale of sand heaps. I will also discuss numerical techniques used for the surrounding fluid. This can be water in the case of sedimentation or air when one studies the formation of dunes in the desert. The calculation of velocity and pressure field of the fluid are done using multigrid techniques on parallel computers. We will compare the performance of the various techniques and show some benchmarks on the dependence on the size of the system, the density of particles and the number of processors used.

  17. Energy dependence of hadronic activity

    NASA Astrophysics Data System (ADS)

    Gabriel, T. A.; Groom, D. E.; Job, P. K.; Mokhov, N. V.; Stevenson, G. R.

    1994-01-01

    Two features of high-energy hadronic cascades have long been known to shielding specialists: a) in a high-energy hadronic cascade in a given material (incident E ≳ 10 GeV), the relative abundance and spectrum of each hadronic species responsible for most of the energy deposition is independent of the energy or species of the incident hadron, and b) because π0 production bleeds off more and more energy into the electromagnetic sector as the energy of the incident hadron increases, the absolute level of this low-energy hadronic activity ( E ≲ 1 GeV) rises less rapidly than the incident energy, and in fact rises very nearly as a power of the incident energy. Both features are of great importance in hadron calorimetry, where it is the "universal spectrum" which makes possible the definition of an intrinsic {e}/{h}, and the increasing fraction of the energy going into π0's which leads to the energy dependence of {e}/{π}. We present evidence for the "universal spectrum," and use an induction argument and simulation results to demonstrate that the low-energy activity ss Em, with 0.80 ≲ m ≲ 0.85. The hadronic activity produced by incident pions is 15-20% less than that initiated by protons.

  18. 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.

  19. Review of hadrons in medium

    SciTech Connect

    Krein, Gastão

    2016-01-22

    I review the present status in the theoretical and phenomenological understanding of hadron properties in strongly interacting matter. The topics covered are the EMC effect, nucleon structure functions in cold nuclear matter, spectral properties of light vector mesons in hot and cold nuclear matter, and in-medium properties of heavy flavored hadrons.

  20. Silo Collapse under Granular Discharge

    NASA Astrophysics Data System (ADS)

    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 /√{R t }. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. Physics at future hadron colliders

    SciTech Connect

    U. Baur et al.

    2002-12-23

    We discuss the physics opportunities and detector challenges at future hadron colliders. As guidelines for energies and luminosities we use the proposed luminosity and/or energy upgrade of the LHC (SLHC), and the Fermilab design of a Very Large Hadron Collider (VLHC). We illustrate the physics capabilities of future hadron colliders for a variety of new physics scenarios (supersymmetry, strong electroweak symmetry breaking, new gauge bosons, compositeness and extra dimensions). We also investigate the prospects of doing precision Higgs physics studies at such a machine, and list selected Standard Model physics rates.

  8. 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.

  9. Granular cell ameloblastoma of mandible.

    PubMed

    Jansari, Trupti R; Samanta, Satarupa T; Trivedi, Priti P; Shah, Manoj J

    2014-01-01

    Ameloblastoma is a neoplasm of odontogenic epithelium, especially of enamel organ-type tissue that has not undergone differentiation to the point of hard tissue formation. Granular cell ameloblastoma is a rare condition, accounting for 3-5% of all ameloblastoma cases. A 30-year-old female patient presented with the chief complaint of swelling at the right lower jaw region since 1 year. Orthopantomogram and computed tomography scan was suggestive of primary bone tumor. Histopathologically, diagnosis of granular cell ameloblastoma of right mandible was made.

  10. 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.

  11. Geometric morphology of granular materials

    NASA Astrophysics Data System (ADS)

    Schlei, Bernd R.; Prasad, Lakshman; Skourikhine, Alexei N.

    2000-10-01

    We present a new method to transform the spectral pixel information of a micrograph into an affine geometric description, which allows us to analyze the morphology of granular materials. We use spectral and pulse-coupled neural network based segmentation techniques to generate blobs, and a newly developed algorithm to extract dilated contours. A constrained Delaunay tessellation of the contour points results in a triangular mesh. This mesh is the basic ingredient of the Chodal Axis Transform, which provides a morphological decomposition of shapes. Such decomposition allows for grain separation and the efficient computation of the statistical features of granular materials.

  12. Unifying suspension and granular rheology.

    PubMed

    Boyer, François; Guazzelli, Élisabeth; Pouliquen, Olivier

    2011-10-28

    Using an original pressure-imposed shear cell, we study the rheology of dense suspensions. We show that they exhibit a viscoplastic behavior similarly to granular media successfully described by a frictional rheology and fully characterized by the evolution of the friction coefficient μ and the volume fraction ϕ with a dimensionless viscous number I(v). Dense suspension and granular media are thus unified under a common framework. These results are shown to be compatible with classical empirical models of suspension rheology and provide a clear determination of constitutive laws close to the jamming transition.

  13. Forward physics of hadronic colliders

    NASA Astrophysics Data System (ADS)

    Ivanov, I. P.

    2013-12-01

    These lectures were given at the Baikal Summer School on Physics of Elementary Particles and Astrophysics in July 2012. They can be viewed as a concise introduction to hadronic diffraction, to the physics of the Pomeron and related topics.

  14. 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.

  15. 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.

  16. Dynamic granularity of imaging systems

    DOE PAGES

    Geissel, Matthias; Smith, Ian C.; Shores, Jonathon E.; ...

    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

  17. Two types of hadrons

    NASA Astrophysics Data System (ADS)

    Jaffe, R. L.

    2008-05-01

    Resonances and enhancements in meson-meson scattering can be divided into two classes distinguished by their behavior as the number of colors (Nc) in QCD becomes large: The first are ordinary mesons that become stable as Nc → ∞. This class includes textbook qbar q mesons as well as glueballs and hybrids. The second class, extraordinary mesons, are enhancements that disappear as Nc → ∞; they subside into the hadronic continuum. This class includes indistinct and controversial objects that have been classified as qbarqbar qq mesons or meson-meson molecules. Peláez's study of the Nc dependence of unitarized chiral dynamics illustrates both classes: the p-wave ππ and Kπ resonances, the ρ (770) and K∗ (892), behave as ordinary mesons; the s-wave ππ and Kπ enhancements, the σ (600) and κ (800), behave like extraordinary mesons. Ordinary mesons resemble Feshbach resonances while extraordinary mesons look more like effects due to potentials in meson-meson scattering channels. I build and explore toy models along these lines. Finally I discuss some related dynamical issues affecting the interpretation of extraordinary mesons.

  18. 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.

  19. 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)

  20. 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.

  1. A hadronic calorimeter with Glass RPC as sensitive medium

    NASA Astrophysics Data System (ADS)

    Grenier, G.

    2014-09-01

    The SDHCAL technological prototype is a 1 × 1 × 1.3 m3 high-granularity Semi-Digital Hadronic CALorimeter using Glass Resistive Plate Chambers as sensitive medium. It 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. The prototype is made of up to 50 GRPC detectors of 1 m2 size and 3 mm thickness each with an embedded semi-digital electronics readout that is autotriggering and power-pulsed. The GRPC readout is finely segmented into pads of 1 cm2. Measured performances of the GRPC and the full SDHCAL prototype in terms of homogeneity, low noise and energy resolution are presented in this proceeding.

  2. 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

  3. 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.

  4. Characterizing Three Dimensional Granular Materials

    NASA Astrophysics Data System (ADS)

    Chen, David; Bares, Jonathan; Zheng, Hu; Bester, Casey; Behringer, Robert

    2016-11-01

    We use systems of hydrogel particles to determine the microscopic response of 3D granular systems to deformations near jamming. We visualize the particles using a laser scan technique, and we determine the motion of the particles along with their inter-particle forces and contacts from the reconstructed scans. We focus on their response to shear with low friction. NSF-DMF-1206351, NASA NNX15AD38G.

  5. The segmentation of hadron calorimeters

    NASA Astrophysics Data System (ADS)

    Chen, He Sheng

    1987-05-01

    Optimization of the segmentation of large hadron calorimeters is important in order to obtain good resolution for jet physics at minimum construction cost for the next generation of high energy experiments. The principles of the segmentation of hadron calorimeters are discussed. As an example, the Monte Carlo optimization of the segmentation of the L3 hadron calorimeter barrel at CERN is described. Comparisons of results for the reconstructed jet shapes show that the optimum number ADC channels is about 20K for the readout of 450K wires of the proportional chambers. The matching between the sandwiched φ towers and Z towers is the dominant factor for angular resolution. Based on these Monte Carlo simulations, an optimized tower structure is obtained.

  6. History of hadron therapy accelerators.

    PubMed

    Degiovanni, Alberto; Amaldi, Ugo

    2015-06-01

    In the last 60 years, hadron therapy has made great advances passing from a stage of pure research to a well-established treatment modality for solid tumours. In this paper the history of hadron therapy accelerators is reviewed, starting from the first cyclotrons used in the thirties for neutron therapy and passing to more modern and flexible machines used nowadays. The technical developments have been accompanied by clinical studies that allowed the selection of the tumours which are more sensitive to this type of radiotherapy. This paper aims at giving a review of the origin and the present status of hadron therapy accelerators, describing the technological basis and the continuous development of this application to medicine of instruments developed for fundamental science. At the end the present challenges are reviewed.

  7. 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.

  8. 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.

  9. Hadron Contribution to Vacuum Polarisation

    NASA Astrophysics Data System (ADS)

    Davier, M.; Hoecker, A.; Malaescu, B.; Zhang, Z.

    2016-10-01

    Precision tests of the Standard Theory require theoretical predictions taking into account higher-order quantum corrections. Among these vacuum polarisation plays a predominant role. Vacuum polarisation originates from creation and annihilation of virtual particle-antiparticle states. Leptonic vacuum polarisation can be computed from quantum electrodynamics. Hadronic vacuum polarisation cannot because of the non-perturbative nature of QCD at low energy. The problem is remedied by establishing dispersion relations involving experimental data on the cross section for e+ e- annihilation into hadrons. This chapter sets the theoretical and experimental scene and reviews the progress achieved in the last decades thanks to more precise and complete data sets. Among the various applications of hadronic vacuum polarisation calculations, two are emphasised: the contribution to the anomalous magnetic moment of the muon, and the running of the fine structure constant α to the Z mass scale. They are fundamental ingredients to high precision tests of the Standard Theory.

  10. 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.

  11. 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

  12. Hadron scattering, resonances, and QCD

    SciTech Connect

    Briceno, Raul

    2016-12-01

    The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

  13. Properties of b-flavored hadrons

    SciTech Connect

    Jaros, J.A.

    1983-10-01

    Experimental progress in the study of b-flavored hadrons is reviewed. The observation of the B meson, properties of hadronic B decays, semi-leptonic B decays, and the B lifetime are discussed. 30 references.

  14. Granular packing as model glass formers

    NASA Astrophysics Data System (ADS)

    Wang, Yujie

    2017-01-01

    Static granular packings are model hard-sphere glass formers. The nature of glass transition has remained a hotly debated issue. We review recent experimental progresses in using granular materials to study glass transitions. We focus on the growth of glass order with five-fold symmetry in granular packings and relate the findings to both geometric frustration and random first-order phase transition theories.

  15. HGCAL: a High-Granularity Calorimeter for the endcaps of CMS at HL-LHC

    NASA Astrophysics Data System (ADS)

    Magnan, A.-M.

    2017-01-01

    Calorimetry at the High Luminosity LHC (HL-LHC) faces two enormous challenges, particularly in the forward direction: radiation tolerance and unprecedented in-time event pileup. To meet these challenges, the CMS experiment has decided to construct a High Granularity Calorimeter (HGCAL), featuring a previously unrealized transverse and longitudinal segmentation, for both electromagnetic and hadronic compartments. This will facilitate particle-flow-type calorimetry, where the fine structure of showers can be measured and used to enhance particle identification, energy resolution and pileup rejection. The majority of the HGCAL will be based on robust and cost-effective hexagonal silicon sensors with simeq 1 cm2 or 0.5 cm2 hexagonal cell size, with the final five interaction lengths of the hadronic compartment being based on highly segmented plastic scintillator with on-scintillator SiPM readout. We present an overview of the HGCAL project, including the motivation, engineering design, readout/trigger concept and simulated performance.

  16. 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.

  17. Sudden Hadronization in Relativistic Nuclear Collisions

    SciTech Connect

    Rafelski, Johann; Letessier, Jean

    2000-11-27

    We formulate and study a mechanical instability criterion for sudden hadronization of dense matter fireballs formed in 158A GeV Pb-Pb collisions. Considering properties of quark-gluon matter and hadron gas we obtain the phase boundary between these two phases and demonstrate that the required deep quark-gluon-plasma supercooling prior to sudden hadronization has occurred.

  18. Study of radiation damage to the CMS Hadronic Endcap Calorimeter and investigation into new physics using multi-boson measurements

    SciTech Connect

    Belloni, Alberto

    2016-03-31

    This document is the final report for the U.S. D.O.E. Grant No. DE-SC0014088, which covers the period from May 15, 2015 to March 31, 2016. The funded research covered the study of multi-boson final states, culminated in the measurement of the W±γγ and, for the first time at an hadronic collider, of the Zγγ production cross sections. These processes, among the rarest multi-boson final states measurable by LHC experiments, allow us to investigate the possibility of new physics in a model-independent way, by looking for anomalies in the standard model couplings among electroweak bosons. In particular, these 3-boson final states access quartic gauge couplings; the W±γγ analysis performed as a part of this proposal sets limits on anomalies in the WWγγ quartic gauge coupling. The award also covered R&D activities to define a radiation-tolerant material to be used in the incoming upgrade of the CMS hadronic endcap calorimeter. In particular, the usage of a liquid-scintillator-based detector was investigated. The research work performed in this direction has been collected in a paper recently submitted for publication in the Journal of Instrumentation (JINST).

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Exciting Developments in Hadron Spectroscopy

    SciTech Connect

    Seth, Kamal K.

    2006-02-11

    There has been a renaissance in hadron spectroscopy during the last couple of years. Long lost states have been tracked down. Unexpected states are showing up all over, and numerous measurements with unprecedented precision are being reported. A review is presented.

  4. 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.

  5. 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.

  6. 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

  7. Dynamics of wet granular hexagons

    NASA Astrophysics Data System (ADS)

    Baur, Manuel; Huang, Kai

    2017-03-01

    The collective behavior of vibrated hexagonal disks confined in a monolayer is investigated experimentally. Due to the broken circular symmetry, hexagons prefer to rotate upon sufficiently strong driving. Due to the formation of liquid bridges, short-ranged cohesive interactions are introduced upon wetting. Consequently, a nonequilibrium stationary state with the rotating disks self-organized in a hexagonal structure arises. The bond length of the hexagonal structure is slightly smaller than the circumdiameter of a hexagon, indicating geometric frustration. This investigation provides an example where the collective behavior of granular matter is tuned by the shape of individual particles.

  8. HARDROC3, a 3rd generation ASIC with zero suppress for ILC Semi Digital Hadronic Calorimeter

    NASA Astrophysics Data System (ADS)

    Dulucq, F.; Callier, S.; de La Taille, C.; Martin-Chassard, G.; Seguin-Moreau, N.; Zoccarato, Y.

    2017-02-01

    HARDROC is the front end chip designed to read out the Resistive Plate Chambers foreseen for the Digital HAdronic CALorimeter (DHCAL) of the future International Linear Collider. The very fine granularity of the calorimeter implies thousands of electronics channels per cubic meter which is a new feature of "imaging" calorimetry. Moreover, for compactness, chips must be embedded inside the detector making crucial the reduction of the power consumption down to 12 μ W per channel. This is achieved using power-pulsing and online zero-suppression. Around 800 HARDROC3 were produced in 2015. The overall performance and production tests will be detailed.

  9. Thermalization of hadrons via Hagedorn states

    NASA Astrophysics Data System (ADS)

    Beitel, M.; Gallmeister, K.; Greiner, C.

    2014-10-01

    Hagedorn states are characterized by being very massive hadron-like resonances and by not being limited to quantum numbers of known hadrons. To generate such a zoo of different Hagedorn states, a covariantly formulated bootstrap equation is solved by ensuring energy conservation and conservation of baryon number B, strangeness S, and electric charge Q. The numerical solution of this equation provides Hagedorn spectra, which also enable us to obtain the decay width for Hagedorn states needed in cascading decay simulations. A single Hagedorn state cascades by various two-body decay channels subsequently into final stable hadrons. All final hadronic observables such as masses, spectral functions, and decay branching ratios for hadronic feed-down are taken from a hadronic transport model. Strikingly, the final energy spectra of resulting hadrons are exponential, showing a thermal-like distribution with the characteristic Hagedorn temperature.

  10. 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

  11. PRN 2001-2: Acute Toxicity Data Requirements For Granular Pesticide Products, Including Those With Granular Fertilizers in the Product.

    EPA Pesticide Factsheets

    This PR Notice announces guidance intended to streamline the acute toxicity review and classification process for certain granular pesticide products, including those products that contain granular fertilizers.

  12. Granular media in transformation: dynamics and structure

    NASA Astrophysics Data System (ADS)

    Merceron, Aymeric; Jop, Pierre; Sauret, Alban; SVI, CNRS/Saint-Gobain Team

    2015-11-01

    Sintering, glass melting and other industrially relevant processes turn batches of grains into continuous end products. Such processes involve complex and mostly misunderstood chemical and physical transformations of the granular packing. Affecting the contact network, physicochemical reactions entail mechanical rearrangements. But such reorganizations may also trigger new potential reactions. Granular reactive systems are strongly coupled and need investigations for achieving industrial optimizations. This study is focused on how transformations appearing on its components affect the response of the granular packing. Inert brass disks and grains undergoing well-known transformations like volume decrease are mixed and then confined in a vertical 2D cell. While the system reacts, the granular packing is regularly photographed with a high-resolution camera. Events largely distributed both spatially and temporally occur around reactive grains. Thanks to image processing, this reorganization process is then analyzed. Spatial and temporal amplitudes of events are quantified as well as their local and global impacts on the granular structure.

  13. 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).

  14. 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.

  15. Numerical calculation of granular entropy.

    PubMed

    Asenjo, Daniel; Paillusson, Fabien; Frenkel, Daan

    2014-03-07

    We present numerical simulations that allow us to compute the number of ways in which N particles can pack into a given volume V. Our technique modifies the method of Xu, Frenkel, and Liu [Phys. Rev. Lett. 106, 245502 (2011)] and outperforms existing direct enumeration methods by more than 200 orders of magnitude. We use our approach to study the system size dependence of the number of distinct packings of a system of up to 128 polydisperse soft disks. We show that, even though granular particles are distinguishable, we have to include a factor 1=N! to ensure that the entropy does not change when exchanging particles between systems in the same macroscopic state. Our simulations provide strong evidence that the packing entropy, when properly defined, is extensive. As different packings are created with unequal probabilities, it is natural to express the packing entropy as S = − Σ(i)p(i) ln pi − lnN!, where pi denotes the probability to generate the ith packing. We can compute this quantity reliably and it is also extensive. The granular entropy thus (re)defined, while distinct from the one proposed by Edwards [J. Phys. Condens. Matter 2, SA63 (1990)], does have all the properties Edwards assumed.

  16. Numerical Calculation of Granular Entropy

    NASA Astrophysics Data System (ADS)

    Asenjo, Daniel; Paillusson, Fabien; Frenkel, Daan

    2014-03-01

    We present numerical simulations that allow us to compute the number of ways in which N particles can pack into a given volume V. Our technique modifies the method of Xu, Frenkel, and Liu [Phys. Rev. Lett. 106, 245502 (2011)] and outperforms existing direct enumeration methods by more than 200 orders of magnitude. We use our approach to study the system size dependence of the number of distinct packings of a system of up to 128 polydisperse soft disks. We show that, even though granular particles are distinguishable, we have to include a factor 1/N! to ensure that the entropy does not change when exchanging particles between systems in the same macroscopic state. Our simulations provide strong evidence that the packing entropy, when properly defined, is extensive. As different packings are created with unequal probabilities, it is natural to express the packing entropy as S=-∑ipilnpi-lnN!, where pi denotes the probability to generate the ith packing. We can compute this quantity reliably and it is also extensive. The granular entropy thus (re)defined, while distinct from the one proposed by Edwards [J. Phys. Condens. Matter 2, SA63 (1990)], does have all the properties Edwards assumed.

  17. 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.

  18. Exotic Hadrons from B Factories

    NASA Astrophysics Data System (ADS)

    Fulsom, Bryan

    2017-01-01

    The first generation of B-Factories, BaBar and Belle, operated over the previous decade and produced many world-leading measurements related to flavor physics. One of the most important discoveries was that of an apparent four-quark particle, named X(3872). It was the first of a growing X, Y, Z alphabet of exotic hadrons, now numbering more than a dozen, found by the e + e - collider experiments. These multi-quark states represent an unusual departure from the standard description that hadronic matter consists of only two or three quarks. These discoveries have led to the emergence of a new category of physics within heavy meson spectroscopy. This talk will review some of these key experimental results, and highlight the potential of the next generation B-Factory, Belle II, as it begins operation in the coming year.

  19. 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.

  20. 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)

  1. 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

  2. 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.

  3. 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.

  4. Hadron physics from lattice QCD

    NASA Astrophysics Data System (ADS)

    Bietenholz, Wolfgang

    2016-07-01

    We sketch the basic ideas of the lattice regularization in Quantum Field Theory, the corresponding Monte Carlo simulations, and applications to Quantum Chromodynamics (QCD). This approach enables the numerical measurement of observables at the non-perturbative level. We comment on selected results, with a focus on hadron masses and the link to Chiral Perturbation Theory. At last, we address two outstanding issues: topological freezing and the sign problem.

  5. Compensation effects in hadron calorimeters

    SciTech Connect

    Gabriel, T.A.; Bishop, B.L.; Brau, J.; Di Ciaccio, A.; Goodman, M.; Wilson, R.

    1984-01-01

    The pros and cons of utilizing a fissionable material such as /sup 238/U to compensate for the nuclear binding energy losses in a hadron calorimeter are discussed. Fissionable material can return some lost energy to the particle cascade in terms of low-energy neutrons and gamma rays, but electromagnetic sampling inefficiencies (often called transition effects) and the detection medium which tries to convert this energy to a useable signal are just as important. 12 references.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Capillary fracturing in granular media.

    PubMed

    Holtzman, Ran; Szulczewski, Michael L; Juanes, Ruben

    2012-06-29

    We study the displacement of immiscible fluids in deformable, noncohesive granular media. Experimentally, we inject air into a thin bed of water-saturated glass beads and observe the invasion morphology. The control parameters are the injection rate, the bead size, and the confining stress. We identify three invasion regimes: capillary fingering, viscous fingering, and "capillary fracturing," where capillary forces overcome frictional resistance and induce the opening of conduits. We derive two dimensionless numbers that govern the transition among the different regimes: a modified capillary number and a fracturing number. The experiments and analysis predict the emergence of fracturing in fine-grained media under low confining stress, a phenomenon that likely plays a fundamental role in many natural processes such as primary oil migration, methane venting from lake sediments, and the formation of desiccation cracks.

  12. Capillary Fracturing in Granular Media

    NASA Astrophysics Data System (ADS)

    Holtzman, Ran; Szulczewski, Michael L.; Juanes, Ruben

    2012-06-01

    We study the displacement of immiscible fluids in deformable, noncohesive granular media. Experimentally, we inject air into a thin bed of water-saturated glass beads and observe the invasion morphology. The control parameters are the injection rate, the bead size, and the confining stress. We identify three invasion regimes: capillary fingering, viscous fingering, and “capillary fracturing,” where capillary forces overcome frictional resistance and induce the opening of conduits. We derive two dimensionless numbers that govern the transition among the different regimes: a modified capillary number and a fracturing number. The experiments and analysis predict the emergence of fracturing in fine-grained media under low confining stress, a phenomenon that likely plays a fundamental role in many natural processes such as primary oil migration, methane venting from lake sediments, and the formation of desiccation cracks.

  13. 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

  14. 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 §...

  15. 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 §...

  16. 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 §...

  17. 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 §...

  18. 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 §...

  19. 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.

  20. 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.

  1. Energy decay in a granular gas collapse

    NASA Astrophysics Data System (ADS)

    Almazán, Lidia; Serero, Dan; Salueña, Clara; Pöschel, Thorsten

    2017-01-01

    An inelastic hard ball bouncing repeatedly off the ground comes to rest in finite time by performing an infinite number of collisions. Similarly, a granular gas under the influence of external gravity, condenses at the bottom of the confinement due to inelastic collisions. By means of hydrodynamical simulations, we find that the condensation process of a granular gas reveals a similar dynamics as the bouncing ball. Our result is in agreement with both experiments and particle simulations, but disagrees with earlier simplified hydrodynamical description. Analyzing the result in detail, we find that the adequate modeling of pressure plays a key role in continuum modeling of granular matter.

  2. 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.

  3. Validation of Hadronic Models in GEANT4

    SciTech Connect

    Koi, Tatsumi; Wright, Dennis H.; Folger, Gunter; Ivanchenko, Vladimir; Kossov, Mikhail; Starkov, Nikolai; Heikkinen, Aatos; Truscott, Peter; Lei, Fan; Wellisch, Hans-Peter

    2007-09-26

    Geant4 is a software toolkit for the simulation of the passage of particles through matter. It has abundant hadronic models from thermal neutron interactions to ultra relativistic hadrons. An overview of validations in Geant4 hadronic physics is presented based on thin target measurements. In most cases, good agreement is available between Monte Carlo prediction and experimental data; however, several problems have been detected which require some improvement in the models.

  4. 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.

  5. The Emergence of Hadrons from QCD Color

    NASA Astrophysics Data System (ADS)

    Brooks, William; Color Dynamics in Cold Matter (CDCM) Collaboration

    2015-10-01

    The formation of hadrons from energetic quarks, the dynamical enforcement of QCD confinement, is not well understood at a fundamental level. In Deep Inelastic Scattering, modifications of the distributions of identified hadrons emerging from nuclei of different sizes reveal a rich variety of spatial and temporal characteristics of the hadronization process, including its dependence on spin, flavor, energy, and hadron mass and structure. The EIC will feature a wide range of kinematics, allowing a complete investigation of medium-induced gluon bremsstrahlung by the propagating quarks, leading to partonic energy loss. This fundamental process, which is also at the heart of jet quenching in heavy ion collisions, can be studied for light and heavy quarks at the EIC through observables quantifying hadron ``attenuation'' for a variety of hadron species. Transverse momentum broadening of hadrons, which is sensitive to the nuclear gluonic field, will also be accessible, and can be used to test our understanding from pQCD of how this quantity evolves with pathlength, as well as its connection to partonic energy loss. The evolution of the forming hadrons in the medium will shed new light on the dynamical origins of the forces between hadrons, and thus ultimately on the nuclear force. Supported by the Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) of Chile.

  6. 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.

  7. 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)

  8. Noise induces rare events in granular media.

    PubMed

    Khain, Evgeniy; Sander, Leonard M

    2016-09-01

    The granular Leidenfrost effect [B. Meerson, et al., Phys. Rev. Lett. 91, 024301 (2003)PRLTAO0031-900710.1103/PhysRevLett.91.024301; P. Eshuis et al., Phys. Rev. Lett. 95, 258001 (2005)PRLTAO0031-900710.1103/PhysRevLett.95.258001] is the levitation of a mass of granular matter when a wall below the grains is vibrated, giving rise to a hot granular gas below the cluster. We find by simulation that for a range of parameters the system is bistable: the levitated cluster can occasionally break and give rise to two clusters and a hot granular gas above and below. We use techniques from the theory of rare events to compute the mean transition time for breaking to occur. This requires the introduction of a two-component reaction coordinate.

  9. Sliding through a superlight granular medium.

    PubMed

    Pacheco-Vázquez, F; Ruiz-Suárez, J C

    2009-12-01

    We explore the penetration dynamics of an intruder in a granular medium composed of expanded polystyrene spherical particles. Three features distinguish our experiment from others studied so far in granular physics: (a) the impact is horizontal, decoupling the effects of gravity and the drag force; (b) the density of the intruder rho(i) is up to 350 times larger than the density of the granular medium rho(m); and (c) the way the intruder moves through the material, sliding at the bottom of the column with small friction. Under these conditions we find that the final penetration D scales with (rho(i)/rho(m)) and the drag force Fd and D saturate with the height of the granular bed.

  10. Two phase granular transport in cylindrical confinement

    NASA Astrophysics Data System (ADS)

    Ayaz, Monem; Toussaint, Renaud; Måløy, Knut-Jørgen

    2016-04-01

    We experimentally study the granular transport properties of a gas/liquid interface as it progresses trough a horizontal capillary tube, filled with a mixture of water and a sedimented granular layer.The displacement dynamics of such dense mixtures exhibit a rheology determined by the frictional interactions between the individual grains, capillary thresholds and the viscous interactions. By direct imaging and pressure measurements we observe different transport regimes as the pumping rate is varied. We classify these regimes according to the observed predominance of frictional or viscous interactions in a phase diagram. For the frictional regime the granular material is not transported out of the tube but structured in a pattern, characterized by its series of granular plugs and gaps. with the pressure signal displaying intermittent stick-slip behavior.

  11. Granular crystals: Nonlinear dynamics meets materials engineering

    DOE PAGES

    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.

  12. Quark forces from hadronic spectroscopy.

    PubMed

    Pirjol, Dan; Schat, Carlos

    2009-04-17

    We consider the implications of the most general two-body quark-quark interaction Hamiltonian for the spin-flavor structure of the negative parity L = 1 excited baryons. Assuming the most general two-body quark interaction Hamiltonian, we derive two correlations among the masses and mixing angles of these states, which constrain the mixing angles, and can be used to test for the presence of three-body quark interactions. We find that the pure gluon-exchange model is disfavored by data, independently of any assumptions about hadronic wave functions.

  13. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, Jicai; Hwa, Rudolph C.

    1992-12-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ecco is extended to three-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in lnpT, and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle φ. The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent ν=1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  14. Multidimensional intermittency in hadronic collisions

    NASA Astrophysics Data System (ADS)

    Pan, J.; Hwa, R. C.

    1992-06-01

    The study of intermittency in high-energy hadronic collisions by the Monte Carlo code ECCO is extended to 3-dimensional phase space. Strong intermittency is found in agreement with the data. Fluctuation in the impact parameter is responsible for the intermittency in 1np(sub T), and the transverse-momentum conservation leads to negative intermittency slopes in the azimuthal angle (phi). The Ochs-Wosiek plots are linear in all dimensions having universal slopes. An exponent nu = 1.448 emerges to characterize multiparticle production in pp collisions. The properties of G moments are also examined, and the fractal dimensions determined.

  15. LHC: The Large Hadron Collider

    ScienceCinema

    Lincoln, Don

    2016-07-12

    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. 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.

  17. Recent results from hadron colliders

    SciTech Connect

    Frisch, H.J. )

    1990-12-10

    This is a summary of some of the many recent results from the CERN and Fermilab colliders, presented for an audience of nuclear, medium-energy, and elementary particle physicists. The topics are jets and QCD at very high energies, precision measurements of electroweak parameters, the remarkably heavy top quark, and new results on the detection of the large flux of B mesons produced at these machines. A summary and some comments on the bright prospects for the future of hadron colliders conclude the talk. 39 refs., 44 figs., 3 tabs.

  18. 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.

  19. Small-signal analysis of granular semiconductors

    NASA Astrophysics Data System (ADS)

    Varpula, Aapo; Sinkkonen, Juha; Novikov, Sergey

    2010-11-01

    The small-signal ac response of granular n-type semiconductors is calculated analytically using the drift-diffusion theory when electronic trapping at grain boundaries is present. An electrical equivalent circuit (EEC) model of a granular n-type semiconductor is presented. The analytical model is verified with numerical simulation performed by SILVACO ATLAS. The agreement between the analytical and numerical results is very good in a broad frequency range at low dc bias voltages.

  20. A constitutive law for dense granular flows.

    PubMed

    Jop, Pierre; Forterre, Yoël; Pouliquen, Olivier

    2006-06-08

    A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.

  1. [Granular cell tumor of the larynx].

    PubMed

    Modrzyński, M; Wróbel, B; Zawisza, E; Drozd, K

    1999-09-01

    Granular cell tumor is an unusual growth of probably neuroectodermal histogenesis, first reported by Abrikossoff in 1926 with the name of myoblastenmyoma. Authors described a case of a 54 year man with laryngeal seat of granular-cell myoblastoma. In this case Abrikossoff tumor was located in the right vocal chord. The tumor was treated successfully surgically by microlaryngoscopy. The etiology, clinical features and diagnostic difficulties are discussed.

  2. Shear dispersion in dense granular flows

    DOE PAGES

    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.

  3. Contact micromechanics in granular media with clay

    SciTech Connect

    Ita, Stacey Leigh

    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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. TOPOLOGICAL THEORY OF HADRONS II: BARYONS

    SciTech Connect

    Stapp, Henry P.

    1981-10-01

    The first paper of this series described a method for incorporating spin into the meson sector of the topological theory of hadrons. This second paper extends the theory to all hadrons. It also incorporates into the covariant S-matrix topological framework the group-theoretic properties of the constituent quark model.

  10. 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.

  11. Driven fragmentation of granular gases.

    PubMed

    Cruz Hidalgo, Raúl; Pagonabarraga, Ignacio

    2008-06-01

    The dynamics of homogeneously heated granular gases which fragment due to particle collisions is analyzed. We introduce a kinetic model which accounts for correlations induced at the grain collisions and analyze both the kinetics and relevant distribution functions these systems develop. The work combines analytical and numerical studies based on direct simulation Monte Carlo calculations. A broad family of fragmentation probabilities is considered, and its implications for the system kinetics are discussed. We show that generically these driven materials evolve asymptotically into a dynamical scaling regime. If the fragmentation probability tends to a constant, the grain number diverges at a finite time, leading to a shattering singularity. If the fragmentation probability vanishes, then the number of grains grows monotonously as a power law. We consider different homogeneous thermostats and show that the kinetics of these systems depends weakly on both the grain inelasticity and driving. We observe that fragmentation plays a relevant role in the shape of the velocity distribution of the particles. When the fragmentation is driven by local stochastic events, the long velocity tail is essentially exponential independently of the heating frequency and the breaking rule. However, for a Lowe-Andersen thermostat, numerical evidence strongly supports the conjecture that the scaled velocity distribution follows a generalized exponential behavior f(c) approximately exp(-cn) , with n approximately 1.2 , regarding less the fragmentation mechanisms.

  12. 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.

  13. Theoretical Model of Granular Compaction

    NASA Astrophysics Data System (ADS)

    Ben-Naim, Eli

    1998-03-01

    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 state follows an anomalously slow inverse logarithmic law. As the density increases, a growing number of grains have to be rearranged to create voids large enough to accommodate a particle. The time for such rearrangements diverges exponentially thereby leading to the logarithmic relaxation. We propose an analytically tractable stochastic process in one dimension that models the excluded volume interaction between grains. In addition to the relaxation towards the steady state, this model predicts the experimentally observed Gaussian distributions and spectrums of the steady state density fluctuations. Work done in collaboration with J. B. Knight, E. R. Nowak, P. L. Krapivsky, H. M. Jaeger, and S. R. Nagel. 1. P. L. Krapivsky and E. Ben-Naim, J. Chem. Phys. 100, 6778 (1994). 2. J. B. Knight, C. G. Fandrich, C. N. Lau, H. M. Jaeger, and S. R. Nagel, Phys. Rev. E 51, 3957 (1995). 3. E. Ben-Naim, J. B. Knight, E. R. Nowak, H. M. Jaeger, and S. R. Nagel, Physica D, in press.

  14. 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).

  15. 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.

  16. Self-assembled granular towers

    NASA Astrophysics Data System (ADS)

    Pacheco-Vazquez, Felipe; Moreau, Florian; Vandewalle, Nicolas; Dorbolo, Stephan; GroupResearch; Applications in Statistical Physics Team

    2013-03-01

    When some water is added to sand, cohesion among the grains is induced. In fact, only 1% of liquid volume respect to the total pore space of the sand is necessary to built impressive sandcastles. Inspired on this experience, the mechanical properties of wet piles and sand columns have been widely studied during the last years. However, most of these studies only consider wet materials with less than 35% of liquid volume. Here we report the spontaneous formation of granular towers produced when dry sand is poured on a highly wet sand bed: The impacting grains stick on the wet grains due to instantaneous liquid bridges created during the impact. The grains become wet by the capillary ascension of water and the process continues, giving rise to stable narrow sand towers. Actually, the towers can reach the maximum theoretical limit of stability predicted by previous models, only expected for low liquid volumes. The authors would like to thank FNRS and Conacyt Mexico for financial support. FPV is a beneficiary of a movility grant from BELSPO/Marie Curie and the University of Liege.

  17. 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

  18. Physicochemical properties of granular and non-granular cationic starches prepared under ultra high pressure.

    PubMed

    Chang, Yoon-Je; Choi, Hyun-Wook; Kim, Hyun-Seok; Lee, Hyungjae; Kim, Wooki; Kim, Dae-Ok; Kim, Byung-Yong; Baik, Moo-Yeol

    2014-01-01

    Granular and non-granular cationic starches were prepared through the reaction of tapioca and corn starches with 2,3-epoxypropyl trimethyl ammonium chloride (ETMAC) using conventional and ultra high pressure (UHP)-assisted reactions. The cationic starches were characterized with respect to morphology, degree of substitution (DS), FT-IR, (13)C NMR, X-ray diffraction pattern, solubility and swelling power, pasting viscosity, and flocculating activity. Non-granular (relative to granular) cationic starches possessed higher DS values. While DS values of non-granular cationic starches were lower for UHP-assisted (relative to conventional) reaction, granular cationic starches did not differ for both reactions. For flocculation activity, granular cationic starches with lower solubility and higher swelling power were higher than non-granular counterparts with reversed patterns in solubility and swelling power, regardless of conventional and UHP-assisted reactions. Overall results suggested that flocculation activity of cationic starches may be directly associated with their swelling powers (relative to DS values).

  19. 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.

  20. 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.

  1. Hadron therapy: history, status, prospects

    NASA Astrophysics Data System (ADS)

    Klenov, G. I.; Khoroshkov, V. S.

    2016-08-01

    A brief historical review is given of external radiation therapy (RT), one of the main cancer treatment methods along with surgery and chemotherapy. Cellular mechanisms of radiation damage are described. Special attention is paid to hadron (proton and ion) therapy, its history, results, problems, challenges, current trends, and prospects. Undeniably great contributions to proton therapy have been made by Russian researchers, notably at the experimental centers that have operated since the mid-20th century at the Joint Institute for Nuclear Research, the A I Alikhanov Institute for Theoretical and Experimental Physics (ITEP), and the B P Konstantinov Petersburg Institute of Nuclear Physics. A quarter of the global clinical experience was accumulated by 1990 at the world's largest ITEP-hosted multicabin proton therapy center.

  2. 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.

  3. Pulling rigid bodies through granular material

    NASA Astrophysics Data System (ADS)

    Kubik, Ryan; Dressaire, Emilie

    2016-11-01

    The need for anchoring systems in granular materials such as sand is present in the marine transportation industry, e.g. to layout moorings, keep vessels and docks fixed in bodies of water, build oil rigs, etc. The holding power of an anchor is associated with the force exerted by the granular media. Empirical evidence indicates that the holding power depends on the size and shape of the anchoring structure. In this model study, we use a two-dimensional geometry in which a rigid body is pulled through a granular media at constant velocity to determine the drag and lift forces exerted by a granular medium on a moving object. The method allows measuring the drag force and recording the trajectory of the rigid object through the sand. We systematically vary the size and geometry of the rigid body, the properties of the granular medium and the extraction speed. For different initial positions of a cylindrical object pulled horizontally through the medium, we record large variations in magnitude of the drag and a significant lift force that pulls the object out of the sand.

  4. 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.

  5. 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.

  6. Di-hadron production at Jefferson Laboratory

    NASA Astrophysics Data System (ADS)

    Anefalos Pereira, Sergio; CLAS Collaboration

    2015-04-01

    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. Pair of hadrons (di-hadron) SIDIS provides information on the nucleon structure and hadronization dynamics that complements single-hadron SIDIS. The study of di-hadrons allow us to study higher twist distribution functions and Dihadron Fragmentation Functions (DiFF). Together with the twist-2 PDFs (f 1, g 1, h 1), 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 direct and unique insights 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 beam-, target- and double-spin asymmetries will be presented.

  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. Granular computing with multiple granular layers for brain big data processing.

    PubMed

    Wang, Guoyin; Xu, Ji

    2014-12-01

    Big data is the term for a collection of datasets so huge and complex that it becomes difficult to be processed using on-hand theoretical models and technique tools. Brain big data is one of the most typical, important big data collected using powerful equipments of functional magnetic resonance imaging, multichannel electroencephalography, magnetoencephalography, Positron emission tomography, near infrared spectroscopic imaging, as well as other various devices. Granular computing with multiple granular layers, referred to as multi-granular computing (MGrC) for short hereafter, is an emerging computing paradigm of information processing, which simulates the multi-granular intelligent thinking model of human brain. It concerns the processing of complex information entities called information granules, which arise in the process of data abstraction and derivation of information and even knowledge from data. This paper analyzes three basic mechanisms of MGrC, namely granularity optimization, granularity conversion, and multi-granularity joint computation, and discusses the potential of introducing MGrC into intelligent processing of brain big data.

  9. Quark Hadron Duality - Recent Jefferson Lab Results

    SciTech Connect

    Niculescu, Maria Ioana

    2016-08-01

    The duality between the partonic and hadronic descriptions of electron--nucleon scattering is a remarkable feature of nuclear interactions. When averaged over appropriate energy intervals the cross section at low energy which is dominated by nucleon resonances resembles the smooth behavior expected from perturbative QCD. Recent Jefferson Lab results indicate that quark-hadron duality is present in a variety of observables, not just the proton F2 structure function. An overview of recent results, especially local quark-hadron duality on the neutron, are presented here.

  10. 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.

  11. Non-perturbative QCD and hadron physics

    NASA Astrophysics Data System (ADS)

    Cobos-Martínez, J. J.

    2016-10-01

    A brief exposition of contemporary non-perturbative methods based on the Schwinger-Dyson (SDE) and Bethe-Salpeter equations (BSE) of Quantum Chromodynamics (QCD) and their application to hadron physics is given. These equations provide a non-perturbative continuum formulation of QCD and are a powerful and promising tool for the study of hadron physics. Results on some properties of hadrons based on this approach, with particular attention to the pion distribution amplitude, elastic, and transition electromagnetic form factors, and their comparison to experimental data are presented.

  12. Hadron scattering and resonances in QCD

    SciTech Connect

    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 pi pi elastic scattering, including the rho resonance, as well as coupled-channel pi K, eta K scattering. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  13. 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.

  14. Granular statistical mechanics - a personal perspective

    NASA Astrophysics Data System (ADS)

    Blumenfeld, R.; Edwards, S. F.

    2014-10-01

    The science of granular matter has expanded from an activity for specialised engineering applications to a fundamental field in its own right. This has been accompanied by an explosion of research and literature, which cannot be reviewed in one paper. A key to progress in this field is the formulation of a statistical mechanical formalism that could help develop equations of state and constitutive relations. This paper aims at reviewing some milestones in this direction. An essential basic step toward the development of any static and quasi-static theory of granular matter is a systematic and useful method to quantify the grain-scale structure and we start with a review of such a method. We then review and discuss the ongoing attempt to construct a statistical mechanical theory of granular systems. Along the way, we will clarify a number of misconceptions in the field, as well as highlight several outstanding problems.

  15. Vibration-induced liquefaction of granular suspensions.

    PubMed

    Hanotin, C; Kiesgen de Richter, S; Marchal, P; Michot, L J; Baravian, C

    2012-05-11

    We investigate the mechanical behavior of granular suspensions subjected to coupled vibrations and shear. At high shear stress, whatever the mechanical vibration energy and bead size, the system behaves like a homogeneous suspension of hard spheres. At low shear stress, in addition to a dependence on bead size, vibration energy drastically influences the viscosity of the material that can decrease by more than 2 orders of magnitude. All experiments can be rationalized by introducing a hydrodynamical Peclet number defined as the ratio between the lubrication stress induced by vibrations and granular pressure. The behavior of vibrated wet and dry granular materials can then be unified by assimilating the hookean stress in dry media to the lubrication stress in suspensions.

  16. 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.

  17. Dynamic Effective Mass of Granular Media

    NASA Astrophysics Data System (ADS)

    Hsu, Chaur-Jian; Johnson, David L.; Ingale, Rohit A.; Valenza, John J.; Gland, Nicolas; Makse, Hernán A.

    2009-02-01

    We develop the concept of frequency dependent effective mass, Mtilde (ω), of jammed granular materials which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of normal room condition or controlled humidity. The dominant features of Mtilde (ω) provide signatures of the dissipation of acoustic modes, elasticity, and aging effects in the granular medium. We perform humidity controlled experiments and interpret the data in terms of a continuum model and a “trap” model of thermally activated capillary bridges at the contact points. The results suggest that attenuation of acoustic waves in granular materials can be influenced significantly by the kinetics of capillary condensation between the asperities at the contacts.

  18. Image superresolution reconstruction via granular computing clustering.

    PubMed

    Liu, Hongbing; Zhang, Fan; Wu, Chang-an; Huang, Jun

    2014-01-01

    The problem of generating a superresolution (SR) image from a single low-resolution (LR) input image is addressed via granular computing clustering in the paper. Firstly, and the training images are regarded as SR image and partitioned into some SR patches, which are resized into LS patches, the training set is composed of the SR patches and the corresponding LR patches. Secondly, the granular computing (GrC) clustering is proposed by the hypersphere representation of granule and the fuzzy inclusion measure compounded by the operation between two granules. Thirdly, the granule set (GS) including hypersphere granules with different granularities is induced by GrC and used to form the relation between the LR image and the SR image by lasso. Experimental results showed that GrC achieved the least root mean square errors between the reconstructed SR image and the original image compared with bicubic interpolation, sparse representation, and NNLasso.

  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. Compaction dynamics of wet granular packings

    NASA Astrophysics Data System (ADS)

    Vandewalle, Nicolas; Ludewig, Francois; Fiscina, Jorge E.; Lumay, Geoffroy

    2013-03-01

    The extremely slow compaction dynamics of wet granular assemblies has been studied experimentally. The cohesion, due to capillary bridges between neighboring grains, has been tuned using different liquids having specific surface tension values. The characteristic relaxation time for compaction τ grows strongly with cohesion. A kinetic model, based on a free volume kinetic equations and the presence of a capillary energy barrier (due to liquid bridges), is able to reproduce quantitatively the experimental curves. This model allows one to describe the cohesion in wet granular packing. The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has also been investigated in the range 20 % - 80 % . Triboelectric and capillary condensation effects have been introduced in the kinetic model. Results confirm the existence of an optimal condition at RH ~ 45 % for minimizing cohesive interactions between glass beads.

  1. Impact compaction of a granular material

    DOE PAGES

    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

  2. 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.

  3. Simulating granular media on the computer

    NASA Astrophysics Data System (ADS)

    Herrmann, H. J.

    Granular materials, like sand or powder, can present very intriguing effects. When shaken, sheared or poured they show segregation, convection and spontaneous fluctuations in densities and stresses. I will discuss the modeling of a granular medium on a computer by simulating a packing of elastic spheres via Molecular Dynamics. Dissipation of energy and shear friction at collisions are included. In the physical range the friction coefficient is found to be a linear function of the angle of repose. On a vibrating plate the formation of convection cells due to walls or amplitude modulations can be observed. The onset of fluidization can be determined and is in good agreement with experiments. Segregation of larger particles is found to be always accompanied by convection cells. There is also ample experimental evidence showing the existence of spontaneous density patterns in granular material flowing through pipes or hoppers. The Molecular Dynamics simulations show that these density fluctuations follow a 1/f α spectrum. I compare this behavior to deterministic one-dimensional traffic models. A model with continuous positions and velocities shows self-organized critical jamming behind a slower car. The experimentally observed effects are also reproduced by Lattice Gas and Boltzmann Lattice Models. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow. We also briefly sketch a thermodynamic formalism for loose granular material. In a dense packing non-linear acoustic phenomena, like the pressure dependence of the sound velocity are studied. Finally the plastic shear bands occurring in large scale deformations of compactified granular media are investigated using an explicit Lagrangian technique.

  4. 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.

  5. Two scenarios for avalanche dynamics in inclined granular layers.

    PubMed

    Börzsönyi, Tamás; Halsey, Thomas C; Ecke, Robert E

    2005-05-27

    We report experimental measurements of avalanche behavior of thin granular layers on an inclined plane for low volume flow rate. The dynamical properties of avalanches were quantitatively and qualitatively different for smooth glass beads compared to irregular granular materials such as sand. Two scenarios for granular avalanches on an incline are identified, and a theoretical explanation for these different scenarios is developed based on a depth-averaged approach that takes into account the differing rheologies of the granular materials.

  6. Entropy driven patterning in vibrofluidized granular materials

    NASA Astrophysics Data System (ADS)

    Galanis, Jennifer

    2008-10-01

    We investigate pattern formation in vertically vibrofluidized rod and sphere granular mixtures confined to quasi-2D containers. In a pure rod system, crowding induces an isotropic-to-nematic phase transition. The inclusion of spheres destabilizes both the isotropic and nematic states. Instead, small independent rod bundles form, where the long axes of rods are closely approximated. To investigate the role of entropy maximization in the granular experiments, we performed strict-2D equilibrium Monte Carlo simulations of hard rods and spheres and found analogous patterning. Similarities and differences between the steady state experiments and equilibrium simulations will be discussed. In collaboration with Daniel Harries, The Hebrew University of Jerusalem.

  7. 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.

  8. 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

  9. SHARE: Statistical hadronization with resonances

    NASA Astrophysics Data System (ADS)

    Torrieri, G.; Steinke, S.; Broniowski, W.; Florkowski, W.; Letessier, J.; Rafelski, J.

    2005-05-01

    interaction feed-down corrections, the observed hadron abundances are obtained. SHARE incorporates diverse physical approaches, with a flexibility of choice of the details of the statistical hadronization model, including the selection of a chemical (non-)equilibrium condition. SHARE also offers evaluation of the extensive properties of the source of particles, such as energy, entropy, baryon number, strangeness, as well as the determination of the best intensive input parameters fitting a set of experimental yields. This allows exploration of a proposed physical hypothesis about hadron production mechanisms and the determination of the properties of their source. Method of solving the problem: Distributions at freeze-out of both the stable particles and the hadronic resonances are set according to a statistical prescription, technically calculated via a series of Bessel functions, using CERN library programs. We also have the option of including finite particle widths of the resonances. While this is computationally expensive, it is necessary to fully implement the essence of the strong interaction dynamics within the statistical hadronization picture. In fact, including finite width has a considerable effect when modeling directly detectable short-lived resonances ( Λ(1520),K, etc.), and is noticeable in fits to experimentally measured yields of stable particles. After production, all hadronic resonances decay. Resonance decays are accomplished by addition of the parent abundances to the daughter, normalized by the branching ratio. Weak interaction decays receive a special treatment, where we introduce daughter particle acceptance factors for both strongly interacting decay products. An interface for fitting to experimental particle ratios of the statistical model parameters with the help of MINUIT[1] is provided. The χ function is defined in the standard way. For an investigated quantity f and experimental error Δ f, χ=((N=N-N. (note that systematic and statistical

  10. 77 FR 59979 - Pure Magnesium (Granular) From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... COMMISSION Pure Magnesium (Granular) From China Determination On the basis of the record \\1\\ developed in the... antidumping duty order on pure magnesium (granular) from China would be likely to lead to continuation or...), entitled Pure Magnesium (Granular) from China: Investigation No.731-TA- 895 (Second Review)....

  11. 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.

  12. Hadrons and Quark-Gluon Plasma

    NASA Astrophysics Data System (ADS)

    Letessier, Jean; Rafelski, Johann

    2002-06-01

    Before matter as we know it emerged, the universe was filled with the primordial state of hadronic matter called quark gluon plasma. This hot soup of quarks and gluon is effectively an inescapable consequence of our current knowledge about the fundamental hadronic interactions, quantum chromodynamics. This book covers the ongoing search to verify this prediction experimentally and discusses the physical properties of this novel form of matter.

  13. Hadron formation from interaction among quarks

    NASA Astrophysics Data System (ADS)

    Tan, Z. G.; Yang, C. B.

    2015-06-01

    This paper deals with the hadronization process of quark system. A phenomenological potential is introduced to describe the interaction between a quark pair. The potential depends on the color charge of those quarks and their relative distances. Those quarks move according to classical equations of motion. Due to the color interaction, coloring quarks are separated to form color neutral clusters which are supposed to be the hadrons.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Dimpling in loose granular sediments

    NASA Astrophysics Data System (ADS)

    Díaz-Hernández, Jose Luis; Yepes, Jorge

    2010-05-01

    Dimpling is the name given to the centimetre-scale collapse of granular deposits covering the interior of alteration shelters in semi-arid badlands. The development of micro-collapses is favoured by the stable conditions found in these shelters, where they are safe from water flows, rain impact, and animal or human traffic. The floor of these shelters is usually covered by several centimetres of sandy sediment resulting from the alteration of the rocky substratum and characterised by apparently very low density and high porosity. We have observed that the dimpling phenomenon does not depend on the mineralogy of the sands and occurs in dry conditions. The dimples are the shapes resulting from this process and are fragile, conical depressions ranging from 1 to 12 cm in diameter. They are generally over 3 cm in depth, depending on the depth of the sandy layer. The dimples can be classified into three groups by diameter (Ø): Ø≤1cm, 1cm≤Ø≤10 cm and Ø≥10 cm. These three morphometrical ranges suggest three evolutionary stages of the shapes. The main mechanisms of evolution are the coalescence of neighbouring dimples and the accommodation of the lateral walls towards more open, stable shapes. In this process, the slope of the dimple walls decreases to the angle of equilibrium, or internal friction angle of the sediment, when they acquire a more stable, dense structure. This evolution occurs naturally over several months. The process begins when sufficient sediment with low apparent density accumulates. This takes place by vertical accretion of particles from the shelter walls, which pile up in a stack-of-cards type structure. The increase in weight of the sediment column causes punctual micro-collapses when the limit of the sediment's self-supporting capacity is reached. The process is gravitational. Thermal variations can also condition the structural instability of the sediment due to the dilation-retraction changes undergone by the sediment grains. We can

  19. Stick-Slip and Granular Force Networks

    NASA Astrophysics Data System (ADS)

    Behringer, Robert; Yu, Peidong

    2008-03-01

    We describe friction/failure experiments for a granular system consisting of photoelastic particles. The goal of the experiments is to provide a microscopic understanding of stick-slip friction for an object that is pulled across a granular material. The granular material consists of a photoelastic disks (bidisperse distribution) that are confined to a vertically oriented channel. A slider that is rough at the grain scale is pulled across the upper surface of the material. The pulling is accomplished by a screw-driven platform that is connected to the slider by a spring. Photoelastic image data are acquired by a camera and light source that move with the platform. Non-periodic stick-slip occurs for the regime of parameters studied here. During a stick event, force builds up in a strong network of force chains in the granular material. When one or more of the chains break, a slip event occurs. Energy changes from these events are power-law distributed. Analysis of failure points and slip events yields the effective friction coefficients, which are broadly scattered. An alternative description involves modeling the force chain network as a collection of springs. Failure of one spring can lead to a cascade and hence the broad distribution of energy losses.

  20. 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.

  1. 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.

  2. ENGINEERING BULLETIN: GRANULAR ACTIVATED CARBON TREATMENT

    EPA Science Inventory

    Granular activated carbon (GAC) treatment is a physicochemical process that removes a wide variety of contaminants by adsorbing them from liquid and gas streams [1, p. 6-3]. This treatment is most commonly used to separate organic contaminants from water or air; however, it can b...

  3. 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.

  4. Granular materials interacting with thin flexible rods

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    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.

  5. Dense granular flows down an inclined plane

    NASA Astrophysics Data System (ADS)

    Ecke, Robert; Borzsonyi, Tamas

    2006-03-01

    Granular flow on a rough inclined plane is an important model system in which to study the basic rules of the dynamics of granular materials. Despite intensive study, many features of such flows are still incompletely understood. For uniformly flowing layers at relatively shallow inclination, we consider experimentally the the basic flow rheology of the granular media and propose new scalings to collapse our data for glass beads and rough sand as a function of inclination angle and particle diameter. At steep inclinations above some angle θs (θs/θr 1.3-1.5, where θr stands for the angle of repose) for flowing grains, numerics and theory predict that the surface roughness is inadequate to dissipate energy gained in the gravitational field, and the flow should continue to accelerate. We report on our experimental results on the properties of granular flows on a steeply inclined plane and define the domains of steady flows. We also discuss the instabilities of such flows leading to spatial patterns.

  6. Granular avalanches down inclined and vibrated planes.

    PubMed

    Gaudel, Naïma; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Jenny, Mathieu; Skali-Lami, Salaheddine

    2016-09-01

    In this article, we study granular avalanches when external mechanical vibrations are applied. We identify conditions of flow arrest and compare with the ones classically observed for nonvibrating granular flows down inclines [Phys. Fluids 11, 542 (1999)PHFLE61070-663110.1063/1.869928]. We propose an empirical law to describe the thickness of the deposits with the inclination angle and the vibration intensity. The link between the surface velocity and the depth of the flow highlights a competition between gravity and vibrations induced flows. We identify two distinct regimes: (a) gravity-driven flows at large angles where vibrations do not modify dynamical properties but the deposits (scaling laws in this regime are in agreement with the literature for nonvibrating granular flows) and (b) vibrations-driven flows at small angles where no flow is possible without applied vibrations (in this last regime, the flow behavior can be properly described by a vibration induced activated process). We show, in this study, that granular flows down inclined planes can be finely tuned by external mechanical vibrations.

  7. 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…

  8. Localized fluidization in a granular medium.

    PubMed

    Philippe, P; Badiane, M

    2013-04-01

    We present here experimental results on the progressive development of a fluidized zone in a bed of grains, immersed in a liquid, under the effect of a localized upward flow injected through a small orifice at the bottom of the bed. Visualization inside the model granular medium consisting of glass beads is made possible by the combined use of two optical techniques: refractive index matching between the liquid and the beads and planar laser-induced fluorescence. Gradually increasing the injection rate, three regimes are successively observed: static bed, fluidized cavity that does not open to the upper surface of the granular bed, and finally fluidization over the entire height of the granular bed inside a fluidized chimney. The phase diagram is plotted and partially interpreted using a model previously developed by Zoueshtiagh and Merlen [F. Zoueshtiagh and A. Merlen, Phys. Rev. E 75, 053613 (2007)]. A typical sequence, where the flow rate is first increased and then decreased back to zero, reveals a strong hysteretic behavior since the stability of the fluidized cavity is considerably strengthened during the defluidization phase. This effect can be explained by the formation of force arches within the granular packing when the chimney closes up at the top of the bed. A study of the expansion rate of the fluidized cavity was also conducted as well as the analysis of the interaction between two injection orifices with respect to their spacing.

  9. Experimental velocity distributions in a granular submonolayer

    NASA Astrophysics Data System (ADS)

    Cadillo-Martínez, Alejandra T.; Sánchez, Rodrigo

    2017-01-01

    Experimental speed distributions are obtained for driven granular submonolayers of binary mixtures of single spheres and dimers of spheres. The results are well-described by a distribution originally developed for a single-species one-dimensional system. This suggests that such a distribution may be extended to other mixtures such as systems exhibiting aggregation and dissociation.

  10. 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).

  11. Granular avalanches down inclined and vibrated planes

    NASA Astrophysics Data System (ADS)

    Gaudel, Naïma; Kiesgen de Richter, Sébastien; Louvet, Nicolas; Jenny, Mathieu; Skali-Lami, Salaheddine

    2016-09-01

    In this article, we study granular avalanches when external mechanical vibrations are applied. We identify conditions of flow arrest and compare with the ones classically observed for nonvibrating granular flows down inclines [Phys. Fluids 11, 542 (1999), 10.1063/1.869928]. We propose an empirical law to describe the thickness of the deposits with the inclination angle and the vibration intensity. The link between the surface velocity and the depth of the flow highlights a competition between gravity and vibrations induced flows. We identify two distinct regimes: (a) gravity-driven flows at large angles where vibrations do not modify dynamical properties but the deposits (scaling laws in this regime are in agreement with the literature for nonvibrating granular flows) and (b) vibrations-driven flows at small angles where no flow is possible without applied vibrations (in this last regime, the flow behavior can be properly described by a vibration induced activated process). We show, in this study, that granular flows down inclined planes can be finely tuned by external mechanical vibrations.

  12. A predictive, nonlocal rheology for granular flows

    NASA Astrophysics Data System (ADS)

    Kamrin, Ken; Henann, David

    2013-11-01

    We propose a continuum model for flowing granular matter and demonstrate that it quantitatively predicts flow and stress fields in many different geometries. The model is constructed in a step-by-step fashion. First we compose a relation based on existing granular rheological approaches (notably the ``inertial'' granular flow rheology) and point out where the resulting model succeeds and where it does not. The clearest missing ingredient is shown to be the lack of an intrinsic length-scale. To tie flow features more carefully to the characteristic grain size, we compose a nonlocal model that includes a new size-dependent term (with only one new material parameter). This new nonlocal model resolves some outstanding questions in the granular flow literature--of note, it is the first model to predict all features of flows in split-bottom cell geometries, a decade-long open question in the field. In total, we will show that this new model, using three material parameters, quantitatively matches the flow and stress data from over 160 experiments in several different geometries.

  13. Granular slumping on a horizontal surface

    NASA Astrophysics Data System (ADS)

    Lajeunesse, E.; Monnier, J. B.; Homsy, G. M.

    2005-10-01

    We report the results of an experimental investigation of the flow induced by the collapse of a column of granular material (glass beads of diameter d) over a horizontal surface. Two different setups are used, namely, a rectangular channel and a semicircular tube, allowing us to compare two-dimensional and axisymmetric flows, with particular focus on the internal flow structure. In both geometries the flow dynamics and the deposit morphologies are observed to depend primarily on the initial aspect ratio of the granular column a =Hi/Li, where Hi is the height of the initial granular column and Li its length along the flow direction. Two distinct regimes are observed depending on a: an avalanche of the column flanks producing truncated deposits for small a and a column free fall leading to conical deposits for large a. In both geometries the characteristic time scale is the free fall of the granular column τc=√Hi/g . The flow initiated by Coulomb-like failure never involves the whole granular heap but remains localized in a surface layer whose size and shape depend on a and vary in both space and time. Except in the vicinity of the pile foot where the flow is pluglike, velocity profiles measured at the side wall are identical to those commonly observed in steady granular surface flows: the velocity varies linearly with depth in the flowing layer and decreases exponentially with depth in the static layer. Moreover, the shear rate is constant, γ˙=0.3√g /d , independent of the initial aspect ratio, the flow geometry, position along the heap, or time. Despite the rather complex flow dynamics, the scaled deposit height Hf/Li and runout distance ΔL /Li both exhibit simple power laws whose exponents depend on a and on the flow geometry. We show that the physical origin of these power laws can be understood on the basis of a dynamic balance between acceleration, pressure gradient, and friction forces at the foot of the granular pile. Two asymptotic behaviors can be

  14. Granular flow over inclined channels with constrictions

    NASA Astrophysics Data System (ADS)

    Tunuguntla, Deepak; Weinhart, Thomas; Thornton, Anthony; Bokhove, Onno

    2013-04-01

    Study of granular flows down inclined channels is essential in understanding the dynamics of natural grain flows like landslides and snow avalanches. As a stepping stone, dry granular flow over an inclined channel with a localised constriction is investigated using both continuum methods and particle simulations. Initially, depth-averaged equations of motion (Savage & Hutter 1989) containing an unknown friction law are considered. The shallow-layer model for granular flows is closed with a friction law obtained from particle simulations of steady flows (Weinhart et al. 2012) undertaken in the open source package Mercury DPM (Mercury 2010). The closed two-dimensional (2D) shallow-layer model is then width-averaged to obtain a novel one-dimensional (1D) model which is an extension of the one for water flows through contraction (Akers & Bokhove 2008). Different flow states are predicted by this novel one-dimensional theory. Flow regimes with distinct flow states are determined as a function of upstream channel Froude number, F, and channel width ratio, Bc. The latter being the ratio of the channel exit width and upstream channel width. Existence of multiple steady states is predicted in a certain regime of F - Bc parameter plane which is in agreement with experiments previously undertaken by (Akers & Bokhove 2008) and for granular flows (Vreman et al. 2007). Furthermore, the 1D model is verified by solving the 2D shallow granular equations using an open source discontinuous Galerkin finite element package hpGEM (Pesch et al. 2007). For supercritical flows i.e. F > 1 the 1D asymptotics holds although the two-dimensional oblique granular jumps largely vary across the converging channel. This computationally efficient closed 1D model is validated by comparing it to the computationally more expensiveaa three-dimensional particle simulations. Finally, we aim to present a quasi-steady particle simulation of inclined flow through two rectangular blocks separated by a gap

  15. 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.

  16. 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.

  17. A correlated-cluster model and the ridge phenomenon in hadron-hadron collisions

    NASA Astrophysics Data System (ADS)

    Sanchis-Lozano, Miguel-Angel; Sarkisyan-Grinbaum, Edward

    2017-03-01

    A study of the near-side ridge phenomenon in hadron-hadron collisions based on a cluster picture of multiparticle production is presented. The near-side ridge effect is shown to have a natural explanation in this context provided that clusters are produced in a correlated manner in the collision transverse plane.

  18. Hadronic interactions in the MINOS detectors

    SciTech Connect

    Kordosky, Michael Alan

    2004-08-01

    MINOS, the Main Injector Neutrino Oscillation Search, will study neutrino flavor transformations using a Near detector at the Fermi National Accelerator Laboratory and a Far detector located in the Soudan Underground Laboratory in northern Minnesota. The MINOS collaboration also constructed the CalDet (calibration detector), a smaller version of the Near and Far detectors, to determine the topological and signal response to hadrons, electrons and muons. The detector was exposed to test-beams in the CERN Proton Synchrotron East Hall during 2001-2003, where it collected events at momentum settings between 200 MeV/c and 10 GeV/c. In this dissertation we present results of the CalDet experiment, focusing on the topological and signal response to hadrons. We briefly describe the MINOS experiment and its iron-scintillator tracking-sampling calorimters as a motivation for the CalDet experiment. We discuss the operation of the CalDet in the beamlines as well as the trigger and particle identification systems used to isolate the hadron sample. The method used to calibrate the MINOS detector is described and validated with test-beam data. The test-beams were simulated to model the muon flux, energy loss upstream of the detector and the kaon background. We describe the procedure used to discriminate between pions and muons on the basis of the event topology. The hadron samples were used to benchmark the existing GEANT3 based hadronic shower codes and determine the detector response and resolution for pions and protons. We conclude with comments on the response to single hadrons and to neutrino induced hadronic showers.

  19. 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

  20. Granular controls of hillslope deformation and creep

    NASA Astrophysics Data System (ADS)

    Ferdowsi, B.; Jerolmack, D. J.; Ortiz, C. P.

    2015-12-01

    Sediment transport on hillslopes has been described as "creep", and has been modeled as a "diffusive" process by invoking random disturbance of soil in the presence of a gradient. In this framework, physical and biological agents are envisioned to cause dilation of the soil that is greatest at the surface and decays with depth. Thus, there is a kind of internal energy of the sediment that allows flow, even below the angle of repose. This transport has not yet been connected, however, to the more general phenomenon of creep in disordered, particulate systems. Work in such "soft matter" materials has shown that disordered solids are fragile, and may deform slowly by localized particle rearrangement under static loads much smaller than the yield stress at which fluid-like flow occurs. The transition from creep to granular flow has not been thoroughly examined. Here we use particle dynamics simulations to examine creep and granular flow dynamics and the transition between them, and to test the ability of a granular physics model to describe observations of hillslope soil creep. We employ a well-developed discrete element model, with frictional and over-damped interactions among grains to approximate the conditions of earth hillslopes. Transient and equilibrium particle dynamics are described for a range of inclination angles that transit the angle of repose. We verify that sub-threshold creep occurs, even in the absence of internal energy, and describe its dynamic signature. Moreover, simulations show that the transition from creeping to a sustained granular flow is continuous as the angle of repose is crossed. We then perturb the granular system with acoustic vibrations, to directly compare the model with previously-reported laboratory experiments of acoustically-driven hillslope transport. We test the ability of the model to reproduce the heuristic nonlinear hillslope flux law. Results reveal that the bulk movement of hillslope sediment over long timescales may be

  1. 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.

  2. Universal effective hadron dynamics from superconformal algebra

    DOE PAGES

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

    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

  3. Universal effective hadron dynamics from superconformal algebra

    SciTech Connect

    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. 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. 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.

  4. 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.

  5. Mechanism and Structure of Subsurface Explosions in Granular Media

    NASA Astrophysics Data System (ADS)

    Lai, Shuyue; Houim, Ryan; Oran, Elaine

    2016-11-01

    Numerical simulations of explosions in granular media were performed with an unsteady multidimensional fully compressible model, which solves two sets of coupled Euler equations, one for the gas and one for the granular medium. An explosive charge, buried in the granular medium, is modeled by a pocket of high-pressure and high-temperature gas. The initial conditions were determined based on an estimate of subsurface conditions on a comet. A series of simulations were performed in which the charge was buried at 3 m and 1.5 m and the particle volume fractions and the coefficient of restitution varied in the ranges 0.25 to 0.45 and 0 to 1, respectively. The simulations show the process of granular shock formation and propagation as a blast wave is created during the explosion. The blast wave initiates the particle motion and the particles accumulate to form a granular shock. The granular shock, in turn, produces a weak gas shock following it. There is a power law that relates the granular-shock radius to the explosion time: R t0.4, which is consistent with the results found by G. I. Taylor for 3-D spherical shock waves. The exponent of the power law remains at 0.4 regardless of the volume fraction and the elasticity of the granular material. For denser granular flows, the intergranular stress becomes stronger, and so the granular shock propagates at a higher velocity.

  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. 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).

  8. 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).

  9. A New Slant on Hadron Structure

    SciTech Connect

    Anthony Thomas; Wolodymyr Melnitchouk; Will Detmold; Stewart Wright; Derek Leinweber

    2001-09-01

    Rather than regarding the restriction of current lattice QCD simulations to quark masses that are 5--10 times larger than those observed, we note that this presents a wonderful opportunity to deepen our understanding of QCD. Just as it has been possible to learn a great deal about QCD by treating N{sub c} as a variable, so the study of hadron properties as a function of quark mass is leading us to a much deeper appreciation of hadron structure. As examples we cite recent progress in using the chiral properties of QCD to connect hadron masses, magnetic moments, charge radii and structure functions calculated at large quark masses within lattice QCD with the values observed physically.

  10. Hadronization of QCD and effective interactions

    SciTech Connect

    Frank, M.R.

    1994-07-01

    An introductory treatment of hadronization through functional integral calculus and bifocal Bose fields is given. Emphasis is placed on the utility of this approach for providing a connection between QCD and effective hadronic field theories. The hadronic interactions obtained by this method are nonlocal due to the QCD substructure, yet, in the presence of an electromagnetic field, maintain the electromagnetic gauge invariance manifest at the quark level. A local chiral model which is structurally consistent with chiral perturbation theory is obtained through a derivative expansion of the nonlocalities with determined, finite coefficients. Tree-level calculations of the pion form factor and {pi} {minus} {pi} scattering, which illustrate the dual constituent-quark-chiral-model nature of this approach, are presented.

  11. Dynamic versus Static Hadronic Structure Functions

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2009-01-09

    'Static' structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the 'dynamic' structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing, and non-universal nuclear antishadowing|novel leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also review how 'direct' higher-twist processes--where a proton is produced in the hard subprocess itself--can explain the anomalous proton-to-pion ratio seen in high centrality heavy ion collisions.

  12. Freeze-out, Hadronization and Statistical Model

    NASA Astrophysics Data System (ADS)

    Castorina, Paolo

    2016-01-01

    The comparison of the statistical hadronization model with experimental data and lattice QCD results is not always straightforward. Indeed, the interpretation of the ϕ meson production, of the proton to pion multiplicity ratio at LHC and the agreement of the freeze-out curve with the lattice critical line in the T — µB plane, require further analyses. Moreover the dynamics of the hadronization has to be compatible with: 1) the statitical behavior also observed in elementary high energy collisions; 2) a universal hadronization temperature for all high energy collisions; 3) the freeze-out criteria. In these lecture notes the SHM is recalled and some explanations of the puzzling aspects of its comparison with data are discussed.

  13. 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.

  14. 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.

  15. Capillary movement of liquid in granular beds

    SciTech Connect

    Yendler, B.; Webbon, B.

    1993-12-31

    Knowledge of capillary migration of liquids in granular beds in microgravity is essential for the development of a substrate based nutrient delivery sytem for the growth of plants in space. This problem is also interesting from the theoretical as well as the practical point of view. The purpose of this study was to model capillary water propagation through a granular bed in microgravity. In our ground experiments, water propagation is driven primarily by capillary force. Data for spherical partical sizes in the range from 0.46 to 2 mm have been obtained. It was shown that the velocity of water propagation is very sensitive to particle size. Theoretical consideration is also provided. Actual space flight experiments are planned for the future to confirm our results.

  16. Movers and shakers: granular damping in microgravity.

    PubMed

    Bannerman, M N; Kollmer, J E; Sack, A; Heckel, M; Mueller, P; Pöschel, T

    2011-07-01

    The response of an oscillating granular damper to an initial perturbation is studied using experiments performed in microgravity and granular dynamics simulations. High-speed video and image processing techniques are used to extract experimental data. An inelastic hard sphere model is developed to perform simulations and the results are in excellent agreement with the experiments. In line with previous work, a linear decay of the amplitude is observed. Although this behavior is typical for a friction-damped oscillator, through simulation it is shown that this effect is still present even when friction forces are absent. A simple expression is developed which predicts the optimal damping conditions for a given amplitude and is independent of the oscillation frequency and particle inelasticities.

  17. Intracranial granular cell tumor in a dog.

    PubMed

    Liu, Chen-Hsuan; Liu, Chen-I; Liang, Sao-Ling; Cheng, Chiung-Hsiang; Huang, Sun-Chau; Lee, Chin-Cheng; Hsu, Wei-Chih; Lin, Yung-Chang

    2004-01-01

    A 12-year-old female miniature poodle showed a 3-month history of neurological signs. Magnetic resonance imaging disclosed a high intensity tumor mass in the right cerebral hemisphere with compression of the lateral ventricle. At necropsy, a 2 x 3 cm white, friable mass was found in the right ventral pyriform lobe. Microscopically, the tumor cells were large, polygonal to round cells supported by a sparse fibrovascular stroma. The tumor cells typically possessed finely granular, pale eosinophilic cytoplasm with strongly positive periodic acid-Schiff (PAS) reaction. The tumor cells were immunopositive for vimentin, NSE and S-100. Ultrastructurally, the tumor cells showed large amounts of granules in the cytoplasm, and absence of basement membrane. Based on the above-mentioned findings, the intracranial granular cell tumor was diagnosed.

  18. 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

  19. 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.

  20. 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.

  1. Erosion dynamics of a wet granular medium.

    PubMed

    Lefebvre, Gautier; Jop, Pierre

    2013-09-01

    Liquid may give strong cohesion properties to a granular medium, and confer a solidlike behavior. We study the erosion of a fixed circular aggregate of wet granular matter subjected to a flow of dry grains inside a half-filled rotating drum. During the rotation, the dry grains flow around the fixed obstacle. We show that its diameter decreases linearly with time for low liquid content, as wet grains are pulled out of the aggregate. This erosion phenomenon is governed by the properties of the liquids. The erosion rate decreases exponentially with the surface tension while it depends on the viscosity to the power -1. We propose a model based on the force fluctuations arising inside the flow, explaining both dependencies: The capillary force acts as a threshold and the viscosity controls the erosion time scale. We also provide experiments using different flowing grains, confirming our model.

  2. 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.

  3. Fracture reveals clustering in cohesive granular matter

    NASA Astrophysics Data System (ADS)

    Tapia, Franco; Santucci, Stéphane; Géminard, Jean-Christophe

    2016-09-01

    We report an experimental study of the morphology of fractures in cohesive granular materials. Cohesion is introduced by equilibrating the grains with a humid atmosphere. The setup allows to produce a controlled crack in a thin layer of a glass beads assembly, and observe with an extremely high resolution the edge of the fracture at the free surface of the layer. The detailed multi-scale analysis of the fracture profile reveals the presence, in the bulk of the material, of clusters of grains whose size increases monotonically with the relative humidity. These results are important because the formation of clusters, resulting in a heterogeneity of the cohesion force, governs the mechanical properties of cohesive granular matter in contact with a humid atmosphere.

  4. 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.

  5. Maximizing energy transfer in vibrofluidized granular systems.

    PubMed

    Windows-Yule, C R K; Rosato, A D; Parker, D J; Thornton, A R

    2015-05-01

    Using discrete particle simulations validated by experimental data acquired using the positron emission particle tracking technique, we study the efficiency of energy transfer from a vibrating wall to a system of discrete, macroscopic particles. We demonstrate that even for a fixed input energy from the wall, energy conveyed to the granular system under excitation may vary significantly dependent on the frequency and amplitude of the driving oscillations. We investigate the manner in which the efficiency with which energy is transferred to the system depends on the system variables and determine the key control parameters governing the optimization of this energy transfer. A mechanism capable of explaining our results is proposed, and the implications of our findings in the research field of granular dynamics as well as their possible utilization in industrial applications are discussed.

  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. Monte Carlo implementation of polarized hadronization

    NASA Astrophysics Data System (ADS)

    Matevosyan, Hrayr H.; Kotzinian, Aram; Thomas, Anthony W.

    2017-01-01

    We study the polarized quark hadronization in a Monte Carlo (MC) framework based on the recent extension of the quark-jet framework, where a self-consistent treatment of the quark polarization transfer in a sequential hadronization picture has been presented. Here, we first adopt this approach for MC simulations of the hadronization process with a finite number of produced hadrons, expressing the relevant probabilities in terms of the eight leading twist quark-to-quark transverse-momentum-dependent (TMD) splitting functions (SFs) for elementary q →q'+h transition. We present explicit expressions for the unpolarized and Collins fragmentation functions (FFs) of unpolarized hadrons emitted at rank 2. Further, we demonstrate that all the current spectator-type model calculations of the leading twist quark-to-quark TMD SFs violate the positivity constraints, and we propose a quark model based ansatz for these input functions that circumvents the problem. We validate our MC framework by explicitly proving the absence of unphysical azimuthal modulations of the computed polarized FFs, and by precisely reproducing the earlier derived explicit results for rank-2 pions. Finally, we present the full results for pion unpolarized and Collins FFs, as well as the corresponding analyzing powers from high statistics MC simulations with a large number of produced hadrons for two different model input elementary SFs. The results for both sets of input functions exhibit the same general features of an opposite signed Collins function for favored and unfavored channels at large z and, at the same time, demonstrate the flexibility of the quark-jet framework by producing significantly different dependences of the results at mid to low z for the two model inputs.

  8. The mechanics of brittle granular materials

    NASA Astrophysics Data System (ADS)

    Einav, Itai

    When considering the modelling of granular materials, use may be made of continuum mechanics principles if the granules are confined. The grain size distribution in these materials evolves with crushing. Therefore, in the continuum mechanics modelling of such matter, the grain size distribution should be taken into account as an internal variable function. In this chapter this idea is explored, first by adopting principles of variational calculus, but then a more accessible theory is motivated based on the concept of breakage.

  9. Seismic wave propagation in granular media

    NASA Astrophysics Data System (ADS)

    Tancredi, Gonzalo; López, Francisco; Gallot, Thomas; Ginares, Alejandro; Ortega, Henry; Sanchís, Johnny; Agriela, Adrián; Weatherley, Dion

    2016-10-01

    Asteroids and small bodies of the Solar System are thought to be agglomerates of irregular boulders, therefore cataloged as granular media. It is a consensus that many asteroids might be considered as rubble or gravel piles.Impacts on their surface could produce seismic waves which propagate in the interior of these bodies, thus causing modifications in the internal distribution of rocks and ejections of particles and dust, resulting in a cometary-type comma.We present experimental and numerical results on the study of propagation of impact-induced seismic waves in granular media, with special focus on behavior changes by increasing compression.For the experiment, we use an acrylic box filled with granular materials such as sand, gravel and glass spheres. Pressure inside the box is controlled by a movable side wall and measured with sensors. Impacts are created on the upper face of the box through a hole, ranging from free-falling spheres to gunshots. We put high-speed cameras outside the box to record the impact as well as piezoelectic sensors and accelerometers placed at several depths in the granular material to detect the seismic wave.Numerical simulations are performed with ESyS-Particle, a software that implements the Discrete Element Method. The experimental setting is reproduced in the numerical simulations using both individual spherical particles and agglomerates of spherical particles shaped as irregular boulders, according to rock models obtained with a 3D scanner. The numerical experiments also reproduces the force loading on one of the wall to vary the pressure inside the box.We are interested in the velocity, attenuation and energy transmission of the waves. These quantities are measured in the experiments and in the simulations. We study the dependance of these three parameters with characteristics like: impact speed, properties of the target material and the pressure in the media.These results are relevant to understand the outcomes of impacts in

  10. 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

  11. Behavior of granular materials under cyclic shear.

    PubMed

    Mueggenburg, Nathan W

    2005-03-01

    The design and development of a parallel plate shear cell for the study of large-scale shear flows in granular materials is presented. The parallel plate geometry allows for shear studies without the effects of curvature found in the more common Couette experiments. A system of independently movable slats creates a well with side walls that deform in response to the motions of grains within the pack. This allows for true parallel plate shear with minimal interference from the containing geometry. The motions of the side walls also allow for a direct measurement of the velocity profile across the granular pack. Results are presented for applying this system to the study of transients in granular shear and for shear-induced crystallization. Initial shear profiles are found to vary from packing to packing, ranging from a linear profile across the entire system to an exponential decay with a width of approximately six bead diameters. As the system is sheared, the velocity profile becomes much sharper, resembling an exponential decay with a width of roughly three bead diameters. Further shearing produces velocity profiles which can no longer be fit to an exponential decay, but are better represented as a Gaussian decay or error function profile. Cyclic shear is found to produce large-scale ordering of the granular pack, which has a profound impact on the shear profile. There exist periods of time in which there is slipping between layers as well as periods of time in which the layered particles lock together resulting in very little relative motion.

  12. 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.

  13. 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.

  14. A Taylor vortex analogy in granular flows.

    PubMed

    Conway, Stephen L; Shinbrot, Troy; Glasser, Benjamin J

    2004-09-23

    Fluids sheared between concentric rotating cylinders undergo a series of three-dimensional instabilities. Since Taylor's archetypal 1923 study, these have proved pivotal to understanding how fluid flows become unstable and eventually undergo transitions to chaotic or turbulent states. In contrast, predicting the dynamics of granular systems--from nano-sized particles to debris flows--is far less reliable. Under shear these materials resemble fluids, but solid-like responses, non-equilibrium structures and segregation patterns develop unexpectedly. As a result, the analysis of geophysical events and the performance of largely empirical particle technologies might suffer. Here, using gas fluidization to overcome jamming, we show experimentally that granular materials develop vortices consistent with the primary Taylor instability in fluids. However, the vortices observed in our fluidized granular bed are unlike those in fluids in that they are accompanied by novel mixing-segregation transitions. The vortices seem to alleviate increased strain by spawning new vortices, directly modifying the scale of kinetic interactions. Our observations provide insights into the mechanisms of shear transmission by particles and their consequent convective mixing.

  15. 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.

  16. 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.

  17. 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.

  18. Structural characterization of submerged granular packings.

    PubMed

    Jakšić, Z M; Šćepanović, J R; Lončarević, I; Budinski-Petković, Lj; Vrhovac, S B; Belić, A

    2014-12-01

    We consider the impact of the effective gravitational acceleration on microstructural properties of granular packings through experimental studies of spherical granular materials saturated within fluids of varying density. We characterize the local organization of spheres in terms of contact connectivity, distribution of the Delaunay free volumes, and the shape factor (parameter of nonsphericity) of the Voronoï polygons. The shape factor gives a clear physical picture of the competition between less and more ordered domains of particles in experimentally obtained packings. As the effective gravity increases, the probability distribution of the shape factor becomes narrower and more localized around the lowest values of the shape factor corresponding to regular hexagon. It is found that curves of the pore distributions are asymmetric with a long tail on the right-hand side, which progressively reduces while the effective gravity gets stronger for lower densities of interstitial fluid. We show that the distribution of local areas (Voronoï cells) broadens with decreasing value of the effective gravity due to the formation of lose structures such as large pores and chainlike structures (arches or bridges). Our results should be particularly helpful in testing the newly developed simulation techniques involving liquid-related forces associated with immersed granular particles.

  19. Structural characterization of submerged granular packings

    NASA Astrophysics Data System (ADS)

    Jakšić, Z. M.; Šćepanović, J. R.; Lončarević, I.; Budinski-Petković, Lj.; Vrhovac, S. B.; Belić, A.

    2014-12-01

    We consider the impact of the effective gravitational acceleration on microstructural properties of granular packings through experimental studies of spherical granular materials saturated within fluids of varying density. We characterize the local organization of spheres in terms of contact connectivity, distribution of the Delaunay free volumes, and the shape factor (parameter of nonsphericity) of the Voronoï polygons. The shape factor gives a clear physical picture of the competition between less and more ordered domains of particles in experimentally obtained packings. As the effective gravity increases, the probability distribution of the shape factor becomes narrower and more localized around the lowest values of the shape factor corresponding to regular hexagon. It is found that curves of the pore distributions are asymmetric with a long tail on the right-hand side, which progressively reduces while the effective gravity gets stronger for lower densities of interstitial fluid. We show that the distribution of local areas (Voronoï cells) broadens with decreasing value of the effective gravity due to the formation of lose structures such as large pores and chainlike structures (arches or bridges). Our results should be particularly helpful in testing the newly developed simulation techniques involving liquid-related forces associated with immersed granular particles.

  20. Drag reduction by rotation in granular media

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We present quantitative measurements and mathematical analysis of the granular drag reduction by rotation inspired by some self-burrowing seeds whose morphologies respond to environmental changes in humidity. The seeds create a motion to dig into soil using their moisture-responsive awns, which are basically helical shaped in a dry environment but reversibly deform to a linear shape in a humid environment. When the tip of the awn is fixed by an external support, the hygroscopic deformation of the awn gives the seed a thrust with rotation against the soil. By measuring the granular drag of vertically penetrating intruders with rotation, we find the drag to decrease with its rotation speed. Noting that the relative motions of the grains in contact with the intruder induce the collapse of the force chains in the granular bulk, we develop a general correlation for the drag reduction by rotation in terms of the relative slip velocity of the grains, which successfully explains the drag reduction of the rotating intruders including self-burrowing rotary seeds.

  1. 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)

  2. 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)

  3. 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

  4. 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)

  5. Granular flow in the marginal ice zone.

    PubMed

    Feltham, Daniel L

    2005-07-15

    The region of sea ice near the edge of the sea ice pack is known as the marginal ice zone (MIZ), and its dynamics are complicated by ocean wave interaction with the ice cover, strong gradients in the atmosphere and ocean and variations in sea ice rheology. This paper focuses on the role of sea ice rheology in determining the dynamics of the MIZ. Here, sea ice is treated as a granular material with a composite rheology describing collisional ice floe interaction and plastic interaction. The collisional component of sea ice rheology depends upon the granular temperature, a measure of the kinetic energy of flow fluctuations. A simplified model of the MIZ is introduced consisting of the along and across momentum balance of the sea ice and the balance equation of fluctuation kinetic energy. The steady solution of these equations is found to leading order using elementary methods. This reveals a concentrated region of rapid ice flow parallel to the ice edge, which is in accordance with field observations, and previously called the ice jet. Previous explanations of the ice jet relied upon the existence of ocean currents beneath the ice cover. We show that an ice jet results as a natural consequence of the granular nature of sea ice.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. Hadron Spectroscopy in Double Pomeron Exchange Experiments

    SciTech Connect

    Albrow, Michael

    2016-11-15

    Central exclusive production in hadron-hadron collisions at high energies, for example p + p -> p + X + p, where the "+" represents a large rapidity gap, is a valuable process for spectroscopy of mesonic states X. At collider energies the gaps can be large enough to be dominated by pomeron exchange, and then the quantum numbers of the state X are restricted. Isoscalar JPC = 0++ and 2++ mesons are selected, and our understanding of these spectra is incomplete. In particular, soft pomeron exchanges favor gluon-dominated states such as glueballs, which are expected in QCD but not yet well established. I will review some published data.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Issues and opportunities in exotic hadrons

    SciTech Connect

    Briceno, Raul A.; Cohen, Thomas D.; Coito, S.; Dudek, Jozef J.; Eichten, E.; Fischer, C. S.; Fritsch, M.; Gradl, W.; Jackura, A.; Kornicer, M.; Krein, G.; Lebed, Richard F.; Machado, F. A.; Mitchell, R. E.; Morningstar, C. J.; Peardon, M.; R. Pennington, M.; Peters, K.; M. Richard, J.; P. Shen, C.; Shepherd, M. R.; Skwarnicki, T.; S. Swanson, E.; Szczepaniak, A. P.; Yuan, C. Z.

    2016-04-01

    The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons. Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks, pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. Consequently, it is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimental and theoretical issues concerning heavy exotic hadrons is presented.

  16. Comparison of hadron shower data in the PAMELA experiment with Geant 4 simulations

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Dunaeva, O. A.; Bogomolov, Yu V.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Rodenko, S. A.

    2017-01-01

    The sampling imaging electromagnetic calorimeter of ≈ 16.3 radiation lengths and ≈ 0.6 nuclear interaction length designed and constructed by the PAMELA collaboration as a part of the large magnetic spectrometer PAMELA. Calorimeter consists of 44 single-sided silicon sensor planes interleaved with 22 plates of tungsten absorber (thickness of each tungsten layer 0.26 cm). Silicon planes are composed of a 3 × 3 matrix of silicon detectors, each segmented into 32 read-out strips with a pitch of 2.4 mm. The orientation of the strips of two consecutive layers is orthogonal and therefore provides two-dimensional spatial information. Due to the high granularity, the development of hadronic showers can be study with a good precision. In this work a Monte Carlo simulations (based on Geant4) performed using different available models, and including detector and physical effects, compared with the experimental data obtained on the near Earth orbit. Response of the PAMELA calorimeter to hadronic showers investigated including total energy release in calorimeter and transverse shower profile characteristics.

  17. Space-time development of electromagnetic and hadronic showers and perspectives for novel calorimetric techniques

    SciTech Connect

    Benaglia, Andrea; Auffray, Etiennette; Lecoq, Paul; Wenzel, Hans; Para, Adam

    2016-04-20

    The performance of hadronic calorimeters will be a key parameter at the next generation of High Energy Physics accelerators. A detector combining fine granularity with excellent timing information would prove beneficial for the reconstruction of both jets and electromagnetic particles with high energy resolution. In this work, the space and time structure of high energy showers is studied by means of a Geant4-based simulation toolkit. In particular, the relevant time scales of the different physics phenomena contributing to the energy loss are investigated. A correlation between the fluctuations of the energy deposition of high energy hadrons and the time development of the showers is observed, which allows for an event-by-event correction to be computed to improve the energy resolution of the calorimeter. Lastly, these studies are intended to set the basic requirements for the development of a new-concept, total absorption time-imaging calorimeter, which seems now within reach thanks to major technological advancements in the production of fast scintillating materials and compact photodetectors.

  18. Space-time development of electromagnetic and hadronic showers and perspectives for novel calorimetric techniques

    DOE PAGES

    Benaglia, Andrea; Auffray, Etiennette; Lecoq, Paul; ...

    2016-04-20

    The performance of hadronic calorimeters will be a key parameter at the next generation of High Energy Physics accelerators. A detector combining fine granularity with excellent timing information would prove beneficial for the reconstruction of both jets and electromagnetic particles with high energy resolution. In this work, the space and time structure of high energy showers is studied by means of a Geant4-based simulation toolkit. In particular, the relevant time scales of the different physics phenomena contributing to the energy loss are investigated. A correlation between the fluctuations of the energy deposition of high energy hadrons and the time developmentmore » of the showers is observed, which allows for an event-by-event correction to be computed to improve the energy resolution of the calorimeter. Lastly, these studies are intended to set the basic requirements for the development of a new-concept, total absorption time-imaging calorimeter, which seems now within reach thanks to major technological advancements in the production of fast scintillating materials and compact photodetectors.« less

  19. Regulation of aerobic granular sludge reformulation after granular sludge broken: effect of poly aluminum chloride (PAC).

    PubMed

    Liu, Yongjun; Liu, Zhe; Wang, Fukun; Chen, Yiping; Kuschk, Peter; Wang, Xiaochang

    2014-04-01

    The present study focuses on the effect of poly aluminum chloride (PAC) on the re-formation of aerobic granular sludge after its rupture. The morphological changes, physical characteristics such as SVI, mechanical strength and surface properties of aerobic granular sludge during the re-formation process of broken granules were investigated. Moreover, components (protein (PN), polysaccharides (PS)) and distributions (soluble, loosely-bound (LB), tightly-bound (TB)) of extracellular polymeric substances (EPS) in sludge flocs were taken into consideration. It was found that the effect of charge neutralization and bridging induced by PAC treatment improved the surface properties of sludge, the re-formed granules had a larger size, more compact structure and that the removal performance of pollutants after chemical coagulation had improved. The results of correlation analysis demonstrated that PN in EPS correlated well with the surface characteristics and settling ability of sludge flocs, and PAC treatment strengthened the influence, further accelerated the reformation of granular sludge.

  20. 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

  1. Medium Modification of Hadronic Interactions from Low Energy Experiments

    NASA Astrophysics Data System (ADS)

    Friedman, E.

    Medium-modification of hadronic interactions is defined as the differences between hadron-hadron interaction in the nuclear medium and the corresponding interaction in free space. Deeply penetrating hadrons provide such information and we discuss here pionic atoms and scattering by nuclei of 21.5 MeV pions. Brief mention is made also of the interaction of 500-700 MeV/c K+ with nuclei.

  2. The Microstructural Response of Granular Soil Under Uniaxial Strain

    DTIC Science & Technology

    1993-10-01

    Mechanics of Granular Materials : New Models and Constitutive Relations, University of Minnesota, Minneapolis, Minnesota, 1983. 23. Trent, B.C...contacts or granular motions will provide insight into more accurate modeling of the material response. The microstructural theory can be directly...use of a flow rule, the ramifications of using an associated or nonassociated flow rule for modeling the response of granular materials will also be

  3. Granular Solid-liquid Transition: Experiment and Simulation

    NASA Astrophysics Data System (ADS)

    Fei, M.; Xu, X.; Sun, Q.

    2015-12-01

    Granular media are amorphous materials, which differs from traditional solid or liquid. In different circumstance, granular behavior varies from solid-like to liquid-like, and the transitions between these regimes are always related to many complex natural progresses such as the failure of soil foundation and the occurrence of landslide and debris flow. The mechanic of elastic instability during the transition from solid-like to liquid-like regime, and the quantitative description of irreversible deformation during flow are the key problems to interpret these transition phenomena. In this work, we developed a continuum model with elastic stable condition and irreversible flow rule of granular material based on a thermal dynamical model, the Two-Granular-Temperature model (TGT). Since infinitesimal elastic deformation in solid-like regime and significant plastic large deformation in liquid-like regime can coexist in the granular solid-liquid transition process, the material point method (MPM) was used to build an effective numerical model. Collapse of rectangular granular pile contains both the transition from granular solid to granular liquid and the inverse process, thus in this work we carried out collapse experiment with clay particles, and simulated the experiment with our continuum model and an open-source DEM model YADE to study the transition processes. Results between experiment and simulations were compared and good agreements on collapse shape and velocity profiles were achieved, and the new model proposed in this work seems to work well on the description of granular solid-liquid transition.

  4. Longitudinally-invariant k⊥-clustering algorithms for hadron-hadron collisions

    NASA Astrophysics Data System (ADS)

    Catani, S.; Dokshitzer, Yu. L.; Seymour, M. H.; Webber, B. R.

    1993-09-01

    We propose a version of the QCD-motivated " k⊥" jet-clustering algorithm for hadron-hadron collisions which is invariant under boosts along the beam directions. This leads to improved factorization properties and closer correspondence to experimental practice at hadron colliders. We examine alternative definitions of the resolution variables and cluster recombination scheme, and show that the algorithm can be implemented efficiently on a computer to provide a full clustering history of each event. Using simulated data at √ S = 1.8 TeV, we study the effects of calorimeter segmentation, hadronization and the soft underlying event, and compare the results with those obtained using a conventional cone-type algorithm.

  5. Black Holes and the Large Hadron Collider

    ERIC Educational Resources Information Center

    Roy, Arunava

    2011-01-01

    The European Center for Nuclear Research or CERN's Large Hadron Collider (LHC) has caught our attention partly due to the film "Angels and Demons." In the movie, an antimatter bomb attack on the Vatican is foiled by the protagonist. Perhaps just as controversial is the formation of mini black holes (BHs). Recently, the American Physical Society…

  6. Lattice studies of hadrons with heavy flavors

    SciTech Connect

    Christopher Aubin

    2009-07-01

    I will discuss recent developments in lattice studies of hadrons composed of heavy quarks. I will mostly cover topics which are at a state of direct comparison with experiment, but will also discuss new ideas and promising techniques to aid future studies of lattice heavy quark physics.

  7. Hard hadronic collisions: extrapolation of standard effects

    SciTech Connect

    Ali, A.; Aurenche, P.; Baier, R.; Berger, E.; Douiri, A.; Fontannaz, M.; Humpert, B.; Ingelman, G.; Kinnunen, R.; Pietarinen, E.

    1984-01-01

    We study hard hadronic collisions for the proton-proton (pp) and the proton-antiproton (p anti p) option in the CERN LEP tunnel. Based on our current knowledge of hard collisions at the present CERN p anti p Collider, and with the help of quantum chromodynamics (QCD), we extrapolate to the next generation of hadron colliders with a centre-of-mass energy E/sub cm/ = 10 to 20 TeV. We estimate various signatures, trigger rates, event topologies, and associated distributions for a variety of old and new physical processes, involving prompt photons, leptons, jets, W/sup + -/ and Z bosons in the final state. We also calculate the maximum fermion and boson masses accessible at the LEP Hadron Collider. The standard QCD and electroweak processes studied here, being the main body of standard hard collisions, quantify the challenge of extracting new physics with hadron colliders. We hope that our estimates will provide a useful profile of the final states, and that our experimental physics colleagues will find this of use in the design of their detectors. 84 references.

  8. BEAM INSTRUMENTATION FOR HIGH POWER HADRON BEAMS

    SciTech Connect

    Aleksandrov, Alexander V

    2013-01-01

    This presentation will describe developments in the beam diagnostics which support the understanding and operation of high power hadron accelerators. These include the measurement of large dynamic range transverse and longitudinal beam profiles, beam loss detection, and non-interceptive diagnostics.

  9. Scaling violation in hadron-nucleus interaction

    NASA Technical Reports Server (NTRS)

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

  10. 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.

  11. 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.

  12. Hadron physics at the COMPASS experiment

    NASA Astrophysics Data System (ADS)

    Krinner, Fabian

    2015-05-01

    Quantum Chromodynamics (QCD), the theory of strong interactions, in principle describes the interaction of quark and gluon fields. However, due to the self-coupling of the gluons, quarks and gluons are confined into hadrons and cannot exist as free particles. The quantitative understanding of this confinement phenomenon, which is responsible for about 98% of the mass of the visible universe, is one of the major open questions in particle physics. The measurement of the excitation spectrum of hadrons and of their properties gives valuable input to theory and phenomenology. In the Constituent Quark Model (CQM) two types of hadrons exist: mesons, made out of a quark and an antiquark, and baryons, which consist of three quarks. But more advanced QCD-inspired models and Lattice QCD calculations predict the existence of hadrons with exotic properties interpreted as excited glue (hybrids) or even pure gluonic bound states (glueballs). The Compass experiment at the CERN Super Proton Synchrotron has acquired large data sets, which allow to study light-quark meson and baryon spectra in unprecedented detail. The presented overview of the first results from this data set focuses in particular on the light meson sector and presents a detailed analysis of three-pion final states. A new JPC = 1++ state, the a1(1420), is observed with a mass and width in the ranges m = 1412 - 1422MeV/c2 and Γ = 130 - 150MeV/c2.

  13. 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.

  14. Mean transverse momenta correlations in hadron-hadron collisions in MC toy model with repulsing strings

    SciTech Connect

    Altsybeev, Igor

    2016-01-22

    In the present work, Monte-Carlo toy model with repulsing quark-gluon strings in hadron-hadron collisions is described. String repulsion creates transverse boosts for the string decay products, giving modifications of observables. As an example, long-range correlations between mean transverse momenta of particles in two observation windows are studied in MC toy simulation of the heavy-ion collisions.

  15. Highlights from Compass in hadron spectroscopy

    NASA Astrophysics Data System (ADS)

    Krinner, Fabian

    2015-06-01

    Since Quantum Choromdynamics allows for gluon self-coupling, quarks and gluons cannot be observed as free particles, but only their bound states, the hadrons. This so-called confinement phenomenon is responsible for 98% of the mass in the visible universe. Measurement of the hadron excitation spectra therefore gives valuable input for theory and phenomenology to quantitatively understand this phenomenon. One simple model to describe hadrons is the Constituent Quark Model (CQM), which knows two types of hadrons: mesons consisting of a quark and an antiquark and baryons, which are made of three quarks. More advanced models, which are inspired by QCD as well as calculations within Lattice QCD, predict the existence of other types of hadrons, which may be, e.g., described solely by gluonic excitations (glueballs) or mixed quark and gluon excitations (hybrids). In order to search for such states, the Compass experiment at the Super Proton Synchrotron at CERN has collected large data sets, which allow to study the light-quark meson and baryon spectra with unmatched precision. The overview shown here focuses on the light meson sector, presenting a detailed Partial-Wave Analysis of the processes: π- p → π-π+π- p and π- p → π-π0π0 p. A new state, the a1(1420) with JPC = 1++, is observed. Its Breit-Wigner parameters are found to be in the ranges: m = 1412 - 1422MeV/c2 and Γ = 130 - 150MeV/c2. In the same analysis, a signal in a wave with JPC = 1- + is observed. A resonant origin of this signal would not be explicable within the CQM. In addition to this possibility of an exotic state, possible non-resonant origin of this signal is discussed.

  16. Segregation induced fingering instabilities in granular avalanches

    NASA Astrophysics Data System (ADS)

    Woodhouse, Mark; Thornton, Anthony; Johnson, Chris; Kokelaar, Pete; Gray, Nico

    2013-04-01

    It is important to be able to predict the distance to which a hazardous natural granular flows (e.g. snow slab avalanches, debris-flows and pyroclastic flows) might travel, as this information is vital for accurate assessment of the risks posed by such events. In the high solids fraction regions of these flows the large particles commonly segregate to the surface, where they are transported to the margins to form bouldery flow fronts. In many natural flows these bouldery margins experience a much greater frictional force, leading to frontal instabilities. These instabilities create levees that channelize the flow vastly increasing the run-out distance. A similar effect can be observed in dry granular experiments, which use a combination of small round and large rough particles. When this mixture is poured down an inclined plane, particle size segregation causes the large particles to accumulate near the margins. Being rougher, the large particles experience a greater friction force and this configuration (rougher material in front of smoother) can be unstable. The instability causes the uniform flow front to break up into a series of fingers. A recent model for particle size-segregation has been coupled to existing avalanche models through a particle concentration dependent friction law. In this talk numerical solutions of this coupled system are presented and compared to both large scale experiments carried out at the USGS flume and more controlled small scale laboratory experiments. The coupled depth-averaged model captures the accumulation of large particles at the flow front. We show this large particle accumulation at the head of the flow can lead to the break-up of the initially uniform front into a series of fingers. However, we are unable to obtain a fully grid-resolved numerical solution; the width of the fingers decreases as the grid is refined. By considering the linear stability of a steady, fully-developed, bidisperse granular layer it is shown that

  17. Clustering in vibrated monolayers of granular rods.

    PubMed

    González-Pinto, M; Borondo, F; Martínez-Ratón, Y; Velasco, E

    2017-04-05

    We investigate the ordering properties of vertically-vibrated monolayers of granular cylinders in a circular container at high packing fraction. In line with previous works by other groups, we identify liquid-crystalline ordering behaviour similar to that of two-dimensional hard rectangular particles subject to thermal equilibrium fluctuations. However, due to dissipation, there is a much stronger tendency for particles to cluster into parallel arrangements in the granular system. These clusters behave as a polydisperse mixture of long life-time 'superparticles', and some aspects of the system behaviour can be understood by applying mean-field theories for equilibrium hard rectangles, based on two-body correlations, to these 'superparticles'. Many other features of the granular system are different: (i) for small particle length-to-breadth ratio κ, we identify tetratic ordering at moderate packing fractions and smectic fluctuations at higher packing fractions, with no sharp transition between the two states. Both types of ordering can be explained in terms of clustering. (ii) For large κ, strong clustering precludes the stabilisation of a uniaxial nematic state, and the system exhibits a mixture of randomly-oriented clusters which, as packing fraction is increased, develops into states with smectic fluctuations, again through a diffuse transition. (iii) Vorticity excitations of the velocity field compete with smectic ordering, causing dynamic fluctuations and the absence of steady states at high densities; the tetratic state, by contrast, is very stiff against vorticity, and long-standing steady states, spatially and orientationally homogeneous except for four symmetrical defects located close to the wall, can be observed.

  18. Size separation in vibrated granular matter

    NASA Astrophysics Data System (ADS)

    Kudrolli, Arshad

    2004-03-01

    We review recent developments in size separation in vibrated granular materials. Motivated by a need in industry to handle granular materials efficiently and a desire to make fundamental advances in non-equilibrium physics, experimental and theoretical investigations have shown size separation to be a complex phenomenon. Large particles in a vibrated granular system normally rise to the top. However, they may also sink to the bottom or show other patterns, depending on subtle variations in physical conditions. While size ratio is a dominant factor, particle-specific properties such as density, inelasticity and friction can play an important role. The nature of the energy input, boundary conditions and interstitial air have also been shown to be significant factors in determining spatial distributions. The presence of convection can enhance mixing or lead to size separation. Experimental techniques including direct visualization and magnetic resonance imaging are being used to investigate these properties. Molecular dynamics and Monte Carlo simulation techniques have been developed to probe size separation. Analytical methods such as kinetic theory are being used to study the interplay between particle size and density in the vibro-fluidized regime, and geometric models have been proposed to describe size separation for deep beds. Besides discussing these studies, we will also review the impact of inelastic collisions and friction on the density and velocity distributions to gain a deeper appreciation of the non-equilibrium nature of the system. While a substantial number of studies have been performed, considerable work is still required to achieve a firm description of the phenomena.

  19. Rolling friction on a granular medium

    NASA Astrophysics Data System (ADS)

    de Blasio, Fabio Vittorio; Saeter, May-Britt

    2009-02-01

    We present experimental results for the rolling of spheres on a granular bed. We use two sets of glass and steel spheres with varying diameters and a high-speed camera to follow the motion of the spheres. Despite the complex phenomena occurring during the rolling, the results show a friction coefficient nearly independent of the velocity (0.45-0.5 for glass and 0.6-0.65 for steel). It is found that for a given sphere density, the large spheres reach a longer distance, a result that may also help explain the rock sorting along natural stone accumulations at the foot of mountain slopes.

  20. Archimedes' principle in fluidized granular systems.

    PubMed

    Huerta, D A; Sosa, Victor; Vargas, M C; Ruiz-Suárez, J C

    2005-09-01

    We fluidize a granular bed in a rectangular container by injecting energy through the lateral walls with high-frequency sinusoidal horizontal vibrations. In this way, the bed is brought to a steady state with no convection. We measured buoyancy forces on light spheres immersed in the bed and found that they obey Archimedes' principle. The buoyancy forces decrease when we reduce the injected energy. By measuring ascension velocities as a function of gamma, we can evaluate the frictional drag of the bed; its exponential dependence agrees very well with previous findings. Rising times of the intruders ascending through the bed were also measured, they increase monotonically as we increase the density.

  1. 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.

  2. 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.

  3. Modelling of dc characteristics for granular semiconductors

    NASA Astrophysics Data System (ADS)

    Varpula, Aapo; Sinkkonen, Juha; Novikov, Sergey

    2010-11-01

    The dc characteristics of granular n-type semiconductors are calculated analytically with the drift-diffusion theory. Electronic trapping at the grain boundaries (GBs) is taken into account. The use of quadratic and linear GB potential profiles in the calculation is compared. The analytical model is verified with numerical simulation performed by SILVACO ATLAS. The agreement between the analytical and numerical results is excellent in a large voltage range. The results show that electronic trapping at the GBs has a remarkable effect on the highly nonlinear I-V characteristics of the material.

  4. Brine Transport Experiments in Granular Salt

    SciTech Connect

    Jordan, Amy B.; Boukhalfa, Hakim; Caporuscio, Florie Andre; Stauffer, Philip H.

    2016-06-06

    To gain confidence in the predictive capability of numerical models, experimental validation must be performed to ensure that parameters and processes are correctly simulated. The laboratory investigations presented herein aim to address knowledge gaps for heat-generating nuclear waste (HGNW) disposal in bedded salt that remain after examination of prior field and laboratory test data. Primarily, we are interested in better constraining the thermal, hydrological, and physicochemical behavior of brine, water vapor, and salt when moist salt is heated. The target of this work is to use run-of-mine (RoM) salt; however during FY2015 progress was made using high-purity, granular sodium chloride.

  5. 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.

  6. 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

  7. Granular Activated Carbon Performance Capability and Availability.

    DTIC Science & Technology

    1983-06-01

    5-11 Notes: 1. As total nitrobodies 2. Combined with RDX 3. Includes dissolved air flotation, sand filter, and GAC 4. Can be achieved with moderate...RDX-HMX Water and Air Research Inc Feoruary 1976 Facility Newoort Army Aunition Plant 0-27 ater Quality Assessment for the Proposed RDX-HMX Water and... Air Research Inc February 1976 Facility, McAlester Naval munition Depot. Vol I 0-28 luorovin Granular Carbon Treatment FMC Corp/EPA 1792-6D" N 07 71

  8. 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.

  9. Nonlinear Phononic Periodic Structures and Granular Crystals

    DTIC Science & Technology

    2012-02-10

    of the advanced delay equation (13) and they compared the numerically obtained solutions with those of approximated PDEs. Recently, Starosvetsky... KdV ), a nonlinear partial differential equation , and have been discovered in myriad systems and discrete nonlinear lattices of all the above types...granular chain, and derived the following KdV equation : t 0 0 1/2 2 2 2 2 0 0 0 0 0 0, 2 6 , , . 6 xx x xc uc A R c R c Rc m σξ ξ γξ ξξ ξ δ γ σ δ

  10. Fluidization of a horizontally driven granular monolayer.

    PubMed

    Heckel, Michael; Sack, Achim; Kollmer, Jonathan E; Pöschel, Thorsten

    2015-06-01

    We consider the transition of a horizontally vibrated monodisperse granular monolayer between its condensed state and its three-dimensional gaseous state as a function of the vibration parameters, amplitude, and frequency as well as particle number density. The transition is characterized by an abrupt change of the dynamical state which leaves its fingerprints in several measurable quantities including dissipation rate, sound emission, and a gap size which characterizes the sloshing motion of the material. The transition and its pronounced hysteresis is explained through the energy due to the collective motion of the particles relative to the container.

  11. Speckle visibility spectroscopy and variable granular fluidization.

    PubMed

    Dixon, P K; Durian, D J

    2003-05-09

    We introduce a dynamic light scattering technique capable of resolving motion that changes systematically, and rapidly, with time. It is based on the visibility of a speckle pattern for a given exposure duration. Applying this to a vibrated layer of glass beads, we measure the granular temperature and its variation with phase in the oscillation cycle. We observe several transitions involving jammed states, where the grains are at rest during some portion of the cycle. We also observe a two-step decay of the temperature on approach to jamming.

  12. Numerical simulations of granular dynamics II: Particle dynamics in a shaken granular material

    NASA Astrophysics Data System (ADS)

    Murdoch, Naomi; Michel, Patrick; Richardson, Derek C.; Nordstrom, Kerstin; Berardi, Christian R.; Green, Simon F.; Losert, Wolfgang

    2012-05-01

    Surfaces of planets and small bodies of our Solar System are often covered by a layer of granular material that can range from a fine regolith to a gravel-like structure of varying depths. Therefore, the dynamics of granular materials are involved in many events occurring during planetary and small-body evolution thus contributing to their geological properties. We demonstrate that the new adaptation of the parallel N-body hard-sphere code pkdgrav has the capability to model accurately the key features of the collective motion of bidisperse granular materials in a dense regime as a result of shaking. As a stringent test of the numerical code we investigate the complex collective ordering and motion of granular material by direct comparison with laboratory experiments. We demonstrate that, as experimentally observed, the scale of the collective motion increases with increasing small-particle additive concentration. We then extend our investigations to assess how self-gravity and external gravity affect collective motion. In our reduced-gravity simulations both the gravitational conditions and the frequency of the vibrations roughly match the conditions on asteroids subjected to seismic shaking, though real regolith is likely to be much more heterogeneous and less ordered than in our idealised simulations. We also show that collective motion can occur in a granular material under a wide range of inter-particle gravity conditions and in the absence of an external gravitational field. These investigations demonstrate the great interest of being able to simulate conditions that are to relevant planetary science yet unreachable by Earth-based laboratory experiments.

  13. Forward Looking Needs Systematised Megatrends in Suitable Granularity

    ERIC Educational Resources Information Center

    Ahamer, Gilbert

    2014-01-01

    Purpose: The purpose of this paper is to inquire about the applicability of the concept of granularity to the necessity of future research or--as often called in the European Union--forward looking (FL). After theoretical deliberation, it uses a planned world-wide information system as a case study for applying the notion of granularity regarding…

  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. 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.

  16. 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.

  17. 75 FR 67105 - Granular Polytetrafluoroethylene Resin From Italy and Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-01

    ...), as most recently amended at 74 FR 2847 (January 16, 2009). \\1\\ No response to this request for... granular polytetrafluoroethylene resin from Japan (53 FR 32267). On August 30, 1988, Commerce issued an antidumping duty order on imports of granular polytetrafluoroethylene resin from Italy (53 FR...

  18. 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...

  19. Granular Cell Tumor of Rectum: A Very Rare Entity

    PubMed Central

    Nagaraj, Savitha V.

    2017-01-01

    Granular cell tumors are predominantly benign, occurring more commonly in women, with about 10% developing in the gastrointestinal tract. Rectal location of this tumor is very rare. We herein report one such case of a 61-year-old man with granular cell tumor in the rectum who underwent endoscopic curative resection. PMID:28255473

  20. Interpreting concept learning in cognitive informatics and granular computing.

    PubMed

    Yao, Yiyu

    2009-08-01

    Cognitive informatics and granular computing are two emerging fields of study concerning information and knowledge processing. A central notion to this processing is information and knowledge granularity. Concepts, as the basic units of thought underlying human intelligence and communication, may play a fundamental role when integrating the results from the two fields in terms of information and knowledge coding, representation, communication, and processing. While cognitive informatics focuses on information processing in the abstract, in machines, and in the brain, granular computing models such processing at multiple levels of granularity. In this paper, we examine a conceptual framework for concept learning from the viewpoints of cognitive informatics and granular computing. Within the framework, we interpret concept learning based on a layered model of knowledge discovery.

  1. 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)

  2. 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.

  3. Discrete particle modelling of granular roll waves

    NASA Astrophysics Data System (ADS)

    Tsang, Jonathan; Dalziel, Stuart; Vriend, Nathalie

    2016-11-01

    A granular current flowing down an inclined chute or plane can undergo an instability that leads to the formation of surface waves, known as roll waves. Examples of roll waves are found in avalanches and debris flows in landslides, and in many industrial processes. Although related to the Kapitza instability of viscous fluid films, granular roll waves are not yet as well understood. Laboratory experiments typically measure the surface height and velocity of a current as functions of position and time, but they do not give insight into the processes below the surface: in particular, the possible formation of a boundary layer at the free surface as well as the base. To overcome this, we are running discrete particle model (DPM) simulations. Simulations are validated against our laboratory experiments, but they also allow us to examine a much larger range of parameters, such as material properties, chute geometry and particle size dispersity, than that which is possible in the lab. We shall present results from simulations in which we vary particle size and dispersity, and examine the implications on roll wave formation and propagation. Future work will include simulations in which the shape of the chute is varied, both cross-sectionally and in the downstream direction. EPSRC studentship (Tsang) and Royal Society Research Fellowship (Vriend).

  4. Size segregation in a granular bore

    NASA Astrophysics Data System (ADS)

    Edwards, A. N.; Vriend, N. M.

    2016-10-01

    We investigate the effect of particle-size segregation in an upslope propagating granular bore. A bidisperse mixture of particles, initially normally graded, flows down an inclined chute and impacts with a closed end. This impact causes the formation of a shock in flow thickness, known as a granular bore, to travel upslope, leaving behind a thick deposit. This deposit imprints the local segregated state featuring both pure and mixed regions of particles as a function of downstream position. The particle-size distribution through the depth is characterized by a thin purely small-particle layer at the base, a significant linear transition region, and a thick constant mixed-particle layer below the surface, in contrast to previously observed S-shaped steady-state concentration profiles. The experimental observations agree with recent progress that upward and downward segregation of large and small particles respectively is asymmetric. We incorporate the three-layer, experimentally observed, size-distribution profile into a depth-averaged segregation model to modify it accordingly. Numerical solutions of this model are able to match our experimental results and therefore motivate the use of a more general particle-size distribution profile.

  5. 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.

  6. Fingering and fracturing in granular media

    NASA Astrophysics Data System (ADS)

    Juanes, R.; Holtzman, R.; Szulczewski, M.

    2012-12-01

    Here, we describe the phenomenon of capillary fracturing in granular media. We study the displacement of immiscible fluids in deformable, non-cohesive granular media. Experimentally, we inject air into a thin bed of water-saturated glass beads and observe the invasion morphology. The control parameters are the injection rate, the bead size, and the confining stress. We identify three invasion regimes: capillary fingering, viscous fingering, and "capillary fracturing", where capillary forces overcome frictional resistance and induce the opening of conduits. We derive two dimensionless numbers that govern the transition among the different regimes: a modified capillary number and a fracturing number. The experiments and analysis predict the emergence of fracturing in fine-grained media under low confining stress, a phenomenon that likely plays a fundamental role in many natural processes such as primary oil migration, methane venting from lake sediments, and the formation of desiccation cracks.Examples of experimentally observed patterns. We classify these patterns into three regimes: viscous fingering, capillary fingering, and fracturing.

  7. 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.

  8. 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.

  9. Dynamic effective mass of granular media

    NASA Astrophysics Data System (ADS)

    Johnson, David; Ingale, Rohit; Valenza, John; Hsu, Chaur-Jian; Gland, Nicolas; Makse, Hernan

    2009-03-01

    We report an experimental and theoretical investigation of the frequency-dependent effective mass, M(φ), of loose granular particles which occupy a rigid cavity to a filling fraction of 48%, the remaining volume being air of differing humidities. We demonstrate that this is a sensitive and direct way to measure those properties of the granular medium that are the cause of the changes in acoustic properties of structures containing grain-filled cavities. Specifically, we apply this understanding to the case of the flexural resonances of a rectangular bar with a grain-filled cavity within it. The dominant features of M(φ) are a sharp resonance and a broad background, which we analyze within the context of simple models. We find that: a) These systems may be understood in terms of a height-dependent and diameter-dependent effective sound speed (˜130 m/s) and an effective viscosity (˜2x10^4 Poise). b) There is a dynamic Janssen effect in the sense that, at any frequency, and depending on the method of sample preparation, approximately one-half of the effective mass is borne by the side walls of the cavity and one-half by the bottom. c) On a fundamental level, dissipation is dominated by adsorbed films of water at grain-grain contacts in our experiments.

  10. Controlling cohesive forces in granular media

    NASA Astrophysics Data System (ADS)

    G"Ogelein, Christoph; Schr"Oter, Matthias; Brinkmann, Martin; Herminghaus, Stephan

    2009-11-01

    When adding a small amount of water to a pile of granular matter, e.g., sand heap, close-by grains can be connected by liquid bridges [1]. Thus, the material becomes plastically and can sustain a larger stress as compared to dry sand. Our general aim is to compare the mechanical properties of wet and dry granular media. For this purpose, we use a suspension of micrometer large glass or Latex spheres dispersed in a binary liquid mixture. The suspending water-lutidine(oil) mixture exhibits a lower critical solution temperature leading to a water-oil-like phase separation slightly above ambient temperature. Close to this demixing region, the oil-like phase undergoes a pre-wetting transition on the particle glass surface inducing liquid bridges [2]. Thus, by varying the temperature we can switch the liquid bridges on and off. We will report on our attempts to directly visualize the formation and control of liquid bridges using confocal and non- confocal microscopy. [4pt] [1] M. Scheel, et al., Nature Materials 7, 174 (2008)[0pt] [2] D. Beysens, and D. Esteve, Phys. Rev. Lett. 54, 2123 (1985)

  11. 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.

  12. Density fluctuations in vibrated granular materials

    SciTech Connect

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

    1998-02-01

    We report systematic measurements of the density of a vibrated granular material as a function of time. Monodisperse spherical beads were confined to a cylindrical container and shaken vertically. Under vibrations, the density of the pile slowly reaches a final steady-state value about which the density fluctuates. We have investigated the frequency dependence and amplitude of these fluctuations as a function of vibration intensity {Gamma}. The spectrum of density fluctuations around the steady state value provides a probe of the internal relaxation dynamics of the system and a link to recent thermodynamic theories for the settling of granular material. In particular, we propose a method to evaluate the compactivity of a powder, first put forth by Edwards and co-workers, that is the analog to temperature for a quasistatic powder. We also propose a stochastic model based on free volume considerations that captures the essential mechanism underlying the slow relaxation. We compare our experimental results with simulations of a one-dimensional model for random adsorption and desorption. {copyright} {ital 1998} {ital The American Physical Society}

  13. 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.

  14. Ultrasonic compaction of granular geological materials.

    PubMed

    Feeney, Andrew; Sikaneta, Sakalima; Harkness, Patrick; Lucas, Margaret

    2017-04-01

    It has been shown that the compaction of granular materials for applications such as pharmaceutical tableting and plastic moulding can be enhanced by ultrasonic vibration of the compaction die. Ultrasonic vibrations can reduce the compaction pressure and increase particle fusion, leading to higher strength products. In this paper, the potential benefits of ultrasonics in the compaction of geological granular materials in downhole applications are explored, to gain insight into the effects of ultrasonic vibrations on compaction of different materials commonly encountered in sub-sea drilling. Ultrasonic vibrations are applied, using a resonant 20kHz compactor, to the compaction of loose sand and drill waste cuttings derived from oolitic limestone, clean quartz sandstone, and slate-phyllite. For each material, a higher strain for a given compaction pressure was achieved, with higher sample density compared to that in the case of an absence of ultrasonics. The relationships between the operational parameters of ultrasonic vibration amplitude and true strain rate are explored and shown to be dependent on the physical characteristics of the compacting materials.

  15. Nonlocal modeling of granular flows down inclines.

    PubMed

    Kamrin, Ken; Henann, David L

    2015-01-07

    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.

  16. 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).

  17. 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).

  18. 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).

  19. 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).

  20. Microstructural characteristics of planar granular solids

    NASA Astrophysics Data System (ADS)

    Matsushima, Takashi; Blumenfeld, Raphael

    2013-06-01

    The microstructure of granular materials is the main factor determining their macroscopic behaviour. We study systematically the statistical characteristics of volume elements (called quadrons) of microstructures of mono-and polydisperse planar disc packs granular and report a number of new results. The packs analysed were of different intergranular friction coefficients, μ, contained about 20,000 discs each and were brought to mechanical equilibrium under identical isotropic compression stresses from three different initial states: loose, intermediate and dense. Our findings are the following. (i) The rattlers volume fraction φr is not affected by the disc size distribution (DSD). (ii) Excluding the rattlers, we find that the relation between the packing fraction φ' and the mean coordination number ¯z is independent of the initial state. Together with result (i), this allows us to separate the effects of the DSD and the initial state on the microstructure. (iii) We relate analytically ¯z, φ' and the (normalised) mean quadron volume ¯ν'. (iv) Combining (iii) and a relation between ¯z and the mean cell order, ē, derived from Euler's topological relation, we show that (ii) is a result of the geometrical relation between ¯ν' and ē. (v) The probability density function of the quadron volumes, normalised by ¯ν', is universal for all the studied systems and it can be fit reasonably well by a Γ distribution.

  1. Thermodynamic Consistency of Mechanical Granular Theories

    NASA Astrophysics Data System (ADS)

    Hutter, K.

    Constitutive Theories of the mechanical behaviour of soils are often derived without resort to thermodynamic considerations. The form of the closure conditions, however, needs to be in conformity with the second law of thermodynamics and depends on it, even on the particular form which the second law is postulated to take. We outline two common forms of the entropy principle, (i) due to Clausius-Duhem and exploited according to Coleman-Noll and (ii) due to I. Müller and exploited ac- cording to Liu. We subject them to certain classes of material behaviour of saturated and unsaturated soil and show that not only the dynamic behaviour depends on the satisfaction of the second law, but equally also that in equilibrium. Examples illus- trating this will be given for (i) a dry soil with voids and exhibiting plastic internal frictional behaviour, (ii) a saturated granular fluid mixture able to model ground water soil interactions as well as (iii) a mixture of a finite number of grains with different diameters that is capable to describe inverse grading of a soil with a broad grain size distribution. In postulating constitutive relations for continuous granular mixtures, the rule of equipresence is often replaced by the rule of phase separation to simplify the com- putations. It is made plausible that, when constituents are strongly interacting, this principle is not likely to yield satisfactory formulations for the intended phenomena.

  2. 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

  3. Origin of Rigidity in Dry Granular Solids

    NASA Astrophysics Data System (ADS)

    Sarkar, Sumantra; Bi, Dapeng; Zhang, Jie; Behringer, R. P.; Chakraborty, Bulbul

    2013-08-01

    Solids are distinguished from fluids by their ability to resist shear. In traditional solids, the resistance to shear is associated with the emergence of broken translational symmetry as exhibited by a nonuniform density pattern. In this work, we focus on the emergence of shear rigidity in a class of solids where this paradigm is challenged. Dry granular materials have no energetically or entropically preferred density modulations. We show that, in contrast to traditional solids, the emergence of shear rigidity in these granular solids is a collective process, which is controlled solely by boundary forces, the constraints of force and torque balance, and the positivity of the contact forces. We develop a theoretical framework based on these constraints, which connects rigidity to broken translational symmetry in the space of forces, not positions of grains. We apply our theory to experimentally generated shear-jammed states and show that these states are indeed characterized by a persistent, non-uniform density modulation in force space, which emerges at the shear-jamming transition.

  4. Theory of hadronic production of heavy quarks

    SciTech Connect

    Peterson, C.

    1981-07-01

    Conventional theoretical predictions for hadronic production of heavy quarks (Q anti Q) are reviewed and confronted with data. Perturbative hard scattering predictions agree qualitatively well with hidden Q anti Q production (e.g., psi, chi, T) whereas for open Q anti Q-production (e.g., pp ..-->.. ..lambda../sub c//sup +/X) additional mechanisms or inputs are needed to explain the forwardly produced ..lambda../sub c//sup +/ at ISR. 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. The theoretical foundations of the intrinsic charm hypotheses together with its consequences for lepton-induced reactions is discussed in some detail.

  5. Trends in accelerator technology for hadron therapy

    NASA Astrophysics Data System (ADS)

    Kostromin, S. A.; Syresin, E. M.

    2013-12-01

    Hadron therapy with protons and carbon ions is one of the most effective branches in radiation oncology. It has advantages over therapy using gamma radiation and electron beams. Fifty thousand patients a year need such treatment in Russia. A review of the main modern trends in the development of accelerators for therapy and treatment techniques concerned with respiratory gated irradiation and scanning with the intensity modulated pencil beams is given. The main stages of formation, time structure, and the main parameters of the beams used in proton therapy, as well as the requirements for medicine accelerators, are considered. The main results of testing with the beam of the C235-V3 cyclotron for the first Russian specialized hospital proton therapy center in Dimitrovgrad are presented. The use of superconducting accelerators and gantry systems for hadron therapy is considered.

  6. Exclusive hadronic decays of B mesons

    NASA Astrophysics Data System (ADS)

    Hölscher, Andreas

    1991-06-01

    The recent experimental results on exclusive hadronic decays of B mesons obtained by the ARGUS collaboration are presented in the talk. The results include exclusive hadronic decays involving a b → c transition, namely B decays with a D, D ∗ plus several pions and B decays to J/ψ or ψ' mesons plus Kaons have been studied. The measurements of branching ratios for two-body B decays involving a J/ψ or ψ' meson are of wide interest in the light of proposals for the study of CP violation in future experiments. The branching ratios are compared with the predictions of the model of Bauer, Stech and Wirbel and with a model of A.V. Dobrovolskaya. Using the cleanest decay channels, the masses and mass difference of the charged and neutral B meson are obtained. This mass difference is then compared with the mass splitting in other isospinmultipletts and with theoretical models.

  7. Quark-Hadron Duality in Electron Scattering

    SciTech Connect

    Wally Melnitchouk; Rolf Ent; Cynthia Keppel

    2004-08-01

    The duality between partonic and hadronic descriptions of physical phenomena is one of the most remarkable features of strong interaction physics. A classic example of this is in electron-nucleon scattering, in which low-energy cross sections, when averaged over appropriate energy intervals, are found to exhibit the scaling behavior expected from perturbative QCD. We present a comprehensive review of data on structure functions in the resonance region, from which the global and local aspects of duality are quantified, including its flavor, spin and nuclear medium dependence. To interpret the experimental findings, we discuss various theoretical approaches which have been developed to understand the microscopic origins of quark-hadron duality in QCD. Examples from other reactions are used to place duality in a broader context, and future experimental and theoretical challenges are identified.

  8. Sources of compensation in hadronic calorimeters

    SciTech Connect

    Goodman, M.S.; Gabriel, T.A.; Di Ciaccio, A.; Wilson, R.

    1988-12-01

    Monte Carlo simulations are presented using the CALOR code system to study the design of a large hybrid hadron calorimeter system employing a warm liquid active medium (tetramethylsilane, Si(CH/sub 3/)/sub 4/) and uranium plates in addition to a conventional Fe/plastic system. In the system described here, the uranium provides partial compensation by suppressing the electromagnetic cascade produced by incident electrons due to sampling inefficiencies. The results of the simulations also indicate that significant compensation is achieved (given small enough saturation) due to low energy recoil protons produced in collisions with low energy (1--20 MeV) cascade and fission neutrons in the active medium. Both compensation mechanisms are important to help balance the response of a calorimeter to incident electrons and hadrons, that is, to achieve a ratio of pulse heights (e/h approx. 1) which will lead to the best energy resolution. 17 refs., 4 figs., 2 tabs.

  9. Production of heavy quarkonia in hadronic experiments

    NASA Astrophysics Data System (ADS)

    Likhoded, A. K.; Luchinsky, A. V.; Poslavsky, S. V.

    2015-12-01

    The phenomenology of the production of P-wave χ c,b mesons and S-wave η c,b mesons in highenergy hadron-hadron collisions was studied on the basis of nonrelativistic quantum chromodynamics (NRQCD). Available experimental data on χ c -meson production were analyzed, and nonperturbative NRQCDmatrix elements were determined from a fit to these data. It is shown that the observed transversemomentum ( pT) spectrum of χ c mesons is basically formed by color-singlet contributions. At the same time, the ratio σ( χ c2)/ σ( χ c1) depends greatly on color-octet contributions; this ratio therefore becomes a highly sensitive tool for separating different NRQCD contributions. Predictions for χ b -meson production are obtained on the basis of NRQCD scaling rules. For the case of η c -meson production, it is shown that the observed cross sections agree with the color-singlet model featuring phenomenological parameters.

  10. Superconformal Algebraic Approach to Hadron Structure

    NASA Astrophysics Data System (ADS)

    de Téramond, Guy F.; Brodsky, Stanley J.; Deur, Alexandre; Dosch, Hans Günter; Sufian, Raza Sabbir

    2017-03-01

    Fundamental aspects of nonperturbative QCD dynamics which are not obvious from its classical Lagrangian, such as the emergence of a mass scale and confinement, the existence of a zero mass bound state, the appearance of universal Regge trajectories and the breaking of chiral symmetry are incorporated from the onset in an effective theory based on superconformal quantum mechanics and its embedding in a higher dimensional gravitational theory. In addition, superconformal quantum mechanics gives remarkable connections between the light meson and nucleon spectra. This new approach to hadron physics is also suitable to describe nonperturbative QCD observables based on structure functions, such as GPDs, which are not amenable to a first-principle computation. The formalism is also successful in the description of form factors, the nonperturbative behavior of the strong coupling and diffractive processes. We also discuss in this article how the framework can be extended rather successfully to the heavy-light hadron sector.

  11. Issues and opportunities in exotic hadrons

    DOE PAGES

    Briceno, Raul A.; Cohen, Thomas D.; Coito, S.; ...

    2016-04-01

    The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons. Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks, pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. Consequently, it is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimentalmore » and theoretical issues concerning heavy exotic hadrons is presented.« less

  12. Hadron Production in Quark and Antiquark Jets

    SciTech Connect

    Muller, David

    1999-09-27

    We present a number of jet fragmentation measurements e{sup +}e{sup -} --> hadrons. The ALEPH collaboration measures inclusive rho{sup 0}(770), f{sub 0}(980) and f{sub 2}(1270) production rates, improving the world averages. The SLD collaboration measures pi{sup {+-}}, K{sup {+-}} and p/anti-p production in light-, c- and b-flavor Z{sup 0} decays, as well as leading hadrons in light-quark jets, precisely. The DELPHI collaboration measures the average charged multiplicity in light- and b-flavor events at 183 and 189 GeV, verifying a precise prediction of QCD and excluding flavor-independent fragmentation.

  13. Unraveling hadron structure with generalized parton distributions

    SciTech Connect

    Andrei Belitsky; Anatoly Radyushkin

    2004-10-01

    The recently introduced generalized parton distributions have emerged as a universal tool to describe hadrons in terms of quark and gluonic degrees of freedom. They combine the features of form factors, parton densities and distribution amplitudes - the functions used for a long time in studies of hadronic structure. Generalized parton distributions are analogous to the phase-space Wigner quasi-probability function of non-relativistic quantum mechanics which encodes full information on a quantum-mechanical system. We give an extensive review of main achievements in the development of this formalism. We discuss physical interpretation and basic properties of generalized parton distributions, their modeling and QCD evolution in the leading and next-to-leading orders. We describe how these functions enter a wide class of exclusive reactions, such as electro- and photo-production of photons, lepton pairs, or mesons.

  14. Many body theory in hadronic physics

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe Jose

    2000-11-01

    This dissertation presents the development of several many body techniques of widespread use in Atomic, Nuclear and Solid State to Hadronic, the low energy Particle Physics that studies strong interactions. For the high energy, asymptotically free, quarks and gluons described by Quantum Chromodynamics, a canonical (BCS) transformation is performed to generate effective low energy degrees of freedom. Then a model Hamiltonian is approximately diagonalized in Fock space using the TDA and RPA formulations. The relativistic wave equations resulting in each sector are numerically solved, yielding mass eigenvalues for the hadronic spectrum. The TDA provides a reasonable approximation for the glueball and meson spectra, with the exception of the light pseudoscalar mesons, where only the RPA correctly incorporates chiral symmetry and the Goldstone boson nature of the pion. Particular attention is devoted to charmed and hybrid mesons, especially exotic states, given the existing data from BNL and prospects of detection at both TJNAF (Hall D) and CERN (Compass).

  15. Hadronic density of states from string theory.

    PubMed

    Pando Zayas, Leopoldo A; Vaman, Diana

    2003-09-12

    We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nùñez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.

  16. The Large Hadron Collider: Redefining High Energy

    SciTech Connect

    Demers, Sarah

    2007-06-19

    Particle physicists have a description of the forces of nature known as the Standard Model that has successfully withstood decades of testing at laboratories around the world. Though the Standard Model is powerful, it is not complete. Important details like the masses of particles are not explained well, and realities as fundamental as gravity, dark matter, and dark energy are left out altogether. I will discuss gaps in the model and why there is hope that some puzzles will be solved by probing high energies with the Large Hadron Collider. Beginning next year, this machine will accelerate protons to record energies, hurling them around a 27 kilometer ring before colliding them 40 million times per second. Detectors the size of five-story buildings will record the debris of these collisions. The new energy frontier made accessible by the Large Hadron Collider will allow thousands of physicists to explore nature's fundamental forces and particles from a fantastic vantage point.

  17. Really large hadron collider working group summary

    SciTech Connect

    Dugan, G.; Limon, P.; Syphers, M.

    1996-12-01

    A summary is presented of preliminary studies of three 100 TeV center-of-mass hadron colliders made with magnets of different field strengths, 1.8T, 9.5T and 12.6T. Descriptions of the machines, and some of the major and most challenging subsystems, are presented, along with parameter lists and the major issues for future study.

  18. Hadronic wavefunctions in light-cone quantization

    SciTech Connect

    Hyer, T.

    1994-05-01

    The analysis of light-cone wavefunctions seems the most promising theoretical approach to a detailed understanding of the structure of relativistic bound states, particularly hadrons. However, there are numerous complications in this approach. Most importantly, the light-cone approach sacrifices manifest rotational invariance in exchange for the elimination of negative-energy states. The requirement of rotational invariance of the full theory places important constraints on proposed light-cone wavefunctions, whether they are modelled or extracted from some numerical procedure. A formulation of the consequences of the hidden rotational symmetry has been sought for some time; it is presented in Chapter 2. In lattice gauge theory or heavy-quark effective theory, much of the focus is on the extraction of numerical values of operators which are related to the hadronic wavefunction. These operators are to some extent interdependent, with relations induced by fundamental constraints on the underlying wavefunction. The consequences of the requirement of unitarity are explored in Chapter 3, and are found to have startling phenomenological relevance. To test model light-cone wavefunctions, experimental predictions must be made. The reliability of perturbative QCD as a tool for making such predictions has been questioned. In Chapter 4, the author presents a computation of the rates for nucleon-antinucleon annihilation, improving the reliability of the perturbative computation by taking into account the Sudakov suppression of exclusive processes at large transverse impact parameter. In Chapter 5, he develops the analysis of semiexclusive production. This work focuses on processes in which a single isolated meson is produced perturbatively and recoils against a wide hadronizing system. At energies above about 10 GeV, semiexclusive processes are shown to be the most sensitive experimental probes of hadronic structure.

  19. Hadron Physics in BaBar

    SciTech Connect

    Lafferty, G.D.; /Manchester U.

    2005-08-29

    Some recent results in hadron physics from the BaBar experiment are discussed. In particular, the observation of two new charmed states, the D*{sub sJ}{sup +}(2317) and the D*{sub sJ}{sup +}(2457), is described, and results are presented on the first measurement of the rare decay mode of the B meson, B{sup 0} {pi}{sup 0}{pi}{sup 0}.

  20. High energy hadron collisions in QCD

    NASA Astrophysics Data System (ADS)

    Levin, E. M.; Ryskin, M. G.

    1990-05-01

    In this review we present the microscopic approach to large cross section physics at high energy, based on the leading logarithmic approximation of perturbative QCD and the reggeon diagram technique. We insist that at high energy the main source of secondary hadrons is the production and fragmentation of the gluon minijets with transverse momentum qt ≈ q0, which rapidly growswith energy, namely q2t≈ q20≈Λ 2 exp(2.5√ln s). Such a large value of the transverse momentum allows us to adopt perturbative QCD for high hadron collisions. The completely avoid the unknown confinement problem, a new scale overlineQ0 ( overlineQ0≈1 GeV, α s( overlineQ20)<1) is introduced in our calculations and only momenta qt> overlineQ0 for gluons are taken into account in any integration. All our results only slightly depend on the value of overlineQ0. It is shown that perturbative QCD is able to describe the main properties of the hedron interactions at high energy, namely, the inclusive spectra of secondary hadrons as functions of y and qt, including small qt⪅300MeV, in a wide energy range √ s=50-900 GeV, the multiplicity distribution, the mean transverse momentum versus multiplicity and so on. We use only three phenomenological parameters in such a description of the experimental data; these values are in agreement with theoretical estimates. Our approach predicts a rapid increase of the mean transverse momentum for secondary hadrons, qt≈ q0, where q0=2.5 GeV at √ S=0.5 TeV, and q0⋍7 GeV at √ S=40 TeV, the total multiplicity N≈ q20, the total cross section σ t≈ln 2s and a comparatively slow increase of the diffraction dissociation cross section σ D≈ln s.

  1. Search for hadronic b-->u decays

    NASA Astrophysics Data System (ADS)

    Albrecht, H.; Gläser, R.; Harder, G.; Krüger, A.; Nilsson, A. W.; Nippe, A.; Oest, T.; Reidenbach, M.; Schäfer, M.; Schmidt-Parzefall, W.; Schröder, H.; Schulz, H. D.; Sefkow, F.; Wurth, R.; Appuhn, R. D.; Drescher, A.; Hast, C.; Herrera, G.; Kolanoski, H.; Lange, A.; Lindner, A.; Mankel, R.; Scheck, H.; Schweda, G.; Spaan, B.; Walther, A.; Wegener, D.; Paulini, M.; Reim, K.; Volland, U.; Wegener, H.; Funk, W.; Stiewe, J.; Werner, S.; Ball, S.; Gabriel, J. C.; Geyer, C.; Hölscher, A.; Hofmann, W.; Holzer, B.; Khan, S.; Spengler, J.; Charlesworth, C. E. K.; Edwards, K. W.; Frisken, W. R.; Kapitza, H.; Krieger, P.; Kutschke, R.; Macfarlene, D. B.; McLean, K. W.; Orr, R. S.; Parsons, J. A.; Patel, P. M.; Prentice, J. D.; Seidel, S. C.; Swain, J. D.; Tsipolitis, G.; Tzamariudaki, K.; Yoon, T.-S.; Ruf, T.; Schael, S.; Schubert, K. R.; Strahl, K.; Waldi, R.; Weseler, S.; Boštjančič, B.; Kernel, G.; Križan, P.; Križnič, E.; Cronström, H. I.; Jönsson, L.; Babaev, A.; Danilo, M.; Fominykh, B.; Golutvin, A.; Gorelov, I.; Lubimov, V.; Rostovtsev, A.; Semenov, A.; Semenov, S.; Shevchenko, V.; Soloshenko, V.; Tchistilin, V.; Tichomirov, I.; Zaitsev, Yu.; Childers, R.; Darden, C. W.; Argus Collaboration

    1990-05-01

    Using the ARGUS detector at the e +e - storage ring DORIS II at DESY, we searched for b→u transitions in exclusive hadronic B meson decays. A systematic analysis of B decays into pions has been performed for decay modes with 2-7 pions in the final state. In none of the decays a positive signal was observed. The upper limits obtained on various branching ratios are consistent with the current model predictions.

  2. Perspectives of hadron therapy in Mexico

    SciTech Connect

    Contreras, J. G.

    2008-08-11

    The need for a hadron therapy center in Mexico is presented. The question if such a facility is affordable in Mexico is discussed, addressing the economical factor as well as the expertise and know how available in both the private and the public sector. To conclude, a possible path, and the first steps on it, to move forward towards a medical facility in Mexico devoted to proton therapy are sketched.

  3. Hadron physics as Seiberg dual of QCD

    SciTech Connect

    Kitano, Ryuichiro

    2012-07-27

    We try to identify the light hadron world as the magnetic picture of QCD. We take both phenomenological and theoretical approaches to this hypothesis, and find that the interpretation seems to show interesting consistencies. In particular, one can identify the {rho} and {omega} mesons as the magnetic gauge bosons, and the Higgs mechanism for them provides a dual picture of the color confinement{sup 1}.

  4. The hadronic final state at HERA

    NASA Astrophysics Data System (ADS)

    Newman, Paul R.; Wing, Matthew

    2014-07-01

    The hadronic final state in electron-proton collisions at HERA has provided a rich testing ground for development of the theory of the strong force, QCD. In this review, over 200 publications from the H1 and ZEUS Collaborations are summarized. Short distance physics, the measurement of processes at high-energy scales, has provided rigorous tests of perturbative QCD and constrained the structure of the proton as well as allowing precise determinations of the strong coupling constant to be made. Nonperturbative or low-energy processes have also been investigated and results on hadronization interpreted together with those from other experiments. Searches for exotic QCD objects, such as pentaquarks, glueballs, and instantons, have been performed. The subject of diffraction has been reinvigorated through its precise measurement, such that it can now be described by perturbative QCD. After discussion of HERA, the H1 and ZEUS detectors, and the techniques used to reconstruct differing hadronic final states, the above subject areas are elaborated on. The major achievements are then condensed further in a final section summarizing what has been learned.

  5. Emergent phenomena and partonic structure in hadrons

    NASA Astrophysics Data System (ADS)

    Roberts, Craig D.; Mezrag, Cédric

    2017-03-01

    Modern facilities are poised to tackle fundamental questions within the Standard Model, aiming to reveal the nature of confinement, its relationship to dynamical chiral symmetry breaking (DCSB) - the origin of visible mass - and the connection between these two, key emergent phenomena. There is strong evidence to suggest that they are intimately connected with the appearance of momentum-dependent masses for gluons and quarks in QCD, which are large in the infrared: mg 500MeV and Mq 350MeV. DCSB, expressed in the dynamical generation of a dressed-quark mass, has an enormous variety of verifiable consequences, including an enigmatic result that the properties of the (almost) massless pion are the cleanest expression of the mechanism which is responsible for almost all the visible mass in the Universe. This contribution explains that these emergent phenomena are expressed with particular force in the partonic structure of hadrons, e.g. in valence-quark parton distribution amplitudes and functions, and, consequently, in numerous hadronic observables, so that we are now in a position to exhibit the consequences of confinement and DCSB in a wide range of hadron observables, opening the way to empirical verification of their expression in the Standard Model.

  6. Controlling wave propagation through nonlinear engineered granular systems

    NASA Astrophysics Data System (ADS)

    Leonard, Andrea

    We study the fundamental dynamic behavior of a special class of ordered granular systems in order to design new, structured materials with unique physical properties. The dynamic properties of granular systems are dictated by the nonlinear, Hertzian, potential in compression and zero tensile strength resulting from the discrete material structure. Engineering the underlying particle arrangement of granular systems allows for unique dynamic properties, not observed in natural, disordered granular media. While extensive studies on 1D granular crystals have suggested their usefulness for a variety of engineering applications, considerably less attention has been given to higher-dimensional systems. The extension of these studies in higher dimensions could enable the discovery of richer physical phenomena not possible in 1D, such as spatial redirection and anisotropic energy trapping. We present experiments, numerical simulation (based on a discrete particle model), and in some cases theoretical predictions for several engineered granular systems, studying the effects of particle arrangement on the highly nonlinear transient wave propagation to develop means for controlling the wave propagation pathways. The first component of this thesis studies the stress wave propagation resulting from a localized impulsive loading for three different 2D particle lattice structures: square, centered square, and hexagonal granular crystals. By varying the lattice structure, we observe a wide range of properties for the propagating stress waves: quasi-1D solitary wave propagation, fully 2D wave propagation with tunable wave front shapes, and 2D pulsed wave propagation. Additionally the effects of weak disorder, inevitably present in real granular systems, are investigated. The second half of this thesis studies the solitary wave propagation through 2D and 3D ordered networks of granular chains, reducing the effective density compared to granular crystals by selectively placing wave

  7. Analysis of hadron yield data within hadron resonance gas model with multi-component eigenvolume corrections

    NASA Astrophysics Data System (ADS)

    Vovchenko, Volodymyr; Stoecker, Horst

    2017-01-01

    We analyze the sensitivity of thermal fits to heavy-ion hadron yield data of ALICE and NA49 collaborations to the systematic uncertainties in the hadron resonance gas (HRG) model related to the modeling of the eigenvolume interactions. We find a surprisingly large sensitivity in extraction of chemical freeze-out parameters to the assumptions regarding eigenvolumes of different hadrons. We additionally study the effect of including yields of light nuclei into the thermal fits to LHC data and find even larger sensitivity to the modeling of their eigenvolumes. The inclusion of light nuclei yields, thus, may lead to further destabilization of thermal fits. Our results show that modeling of eigenvolume interactions plays a crucial role in thermodynamics of HRG and that conclusions based on a non-interacting HRG are inconclusive.

  8. Hadron Production in Heavy Ion Collisions

    SciTech Connect

    Ritter, Hans Georg; Xu, Nu

    2009-05-19

    Heavy ion collisions are an ideal tool to explore the QCD phase diagram. The goal is to study the equation of state (EOS) and to search for possible in-medium modifications of hadrons. By varying the collision energy a variety of regimes with their specific physics interest can be studied. At energies of a few GeV per nucleon, the regime where experiments were performed first at the Berkeley Bevalac and later at the Schwer-Ionen-Synchrotron (SIS) at GSI in Darmstadt, we study the equation of state of dense nuclear matter and try to identify in-medium modifications of hadrons. Towards higher energies, the regime of the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL), the Super-Proton Synchrotron (SPS) at CERN, and the Relativistic Heavy Ion Collider (RHIC) at BNL, we expect to produce a new state of matter, the Quark-Gluon Plasma (QGP). The physics goal is to identify the QGP and to study its properties. By varying the energy, different forms of matter are produced. At low energies we study dense nuclear matter, similar to the type of matter neutron stars are made of. As the energy is increased the main constituents of the matter will change. Baryon excitations will become more prevalent (resonance matter). Eventually we produce deconfined partonic matter that is thought to be in the core of neutron stars and that existed in the early universe. At low energies a great variety of collective effects is observed and a rather good understanding of the particle production has been achieved, especially that of the most abundantly produced pions and kaons. Many observations can be interpreted as time-ordered emission of various particle species. It is possible to determine, albeit model dependent, the equation of state of nuclear matter. We also have seen indications, that the kaon mass, especially the mass of the K{sup +}, might be modified by the medium created in heavy ion collisions. At AGS energies and above, emphasis shifts towards

  9. 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

  10. S-100 Negative Granular Cell Tumor of the Oral Cavity.

    PubMed

    Solomon, Lynn W; Velez, Ines

    2016-09-01

    Classic granular cell tumor is a mesenchymal neoplasm that commonly occurs on the skin, but is not infrequently found in the oral cavity, primarily on the dorsal tongue. Diagnosis is usually straightforward with hematoxylin and eosin stained slides. Immunohistochemical studies on classic granular cell tumor shows positive immunostaining for S-100 and vimentin, while CD68 is variably positive. We report a case of otherwise unremarkable oral granular cell tumor that was immunohistochemically negative for S-100, and positive for vimentin and CD68, and discuss the differential diagnosis. The results of the immunohistochemical studies in our case are compared with those of classic S-100 positive oral granular cell tumors, as well as cutaneous and oral S-100 negative granular cell tumors. Classic S-100 positive granular cell tumors and S-100 negative granular cell tumors of the oral cavity can only be distinguished by immunohistochemical studies; however, the necessity of this distinction is unclear, as both are benign lesions in which recurrence is unlikely.

  11. Collision of a vortex ring on granular material. Part II. Erosion of the granular layer

    NASA Astrophysics Data System (ADS)

    Yoshida, Junya; Masuda, Naoya; Ito, Boku; Furuya, Takayoshi; Sano, Osamu

    2012-02-01

    In our previous paper (part I), an experimental result was presented on the normal impact of a vortex ring on the granular layer (glass beads of diameter 0.10 mm), which was placed at a specified distance from the outlet of the vortex ring generator. The Reynolds number of the vortex ring ranged from 1000 to 6000, whereas the traveling distance ranged from 2 to 13 times of the diameter of the vortex ring generator nozzle. In part I, the deformation of the vortex ring impacting on the granular layer and the development of the secondary vortex ring were focused. In this paper (part II), the erosion of the granular surface by the vortex ring is described. Various patterns were found depending on the Reynolds number of the vortex ring and the traveling distance. Two patterns, one (grooves) which has radial striations from the central depressed region to the outer edge of the rim and the other (dimples) which is characterized by isolated small depressions around the outer edge of the rim, are examined in detail. The formation processes of these patterns are elucidated in terms of the deformation of the vortex ring.

  12. 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.

  13. 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.

  14. Methods of similitude in granular avalanche flows

    NASA Astrophysics Data System (ADS)

    Tai, Yih-Chin; Wang, Yongqi; Gray, J. M. N. T.; Hutter, Kolumban

    Snow avalanches are relatively dry and dense granular flows for which the Savage-Hutter (SH) equations have been demonstrated to be an adequate mathematical model. We review these equations and point out for which cases the equations have been tested against laboratory experiments. Since the equations are scale invariant and because agreement with experiments is good, laboratory experiments can be used to test realistic flows. This is detailed in this paper. We demonstrate how shocks are formed when dilatational flow states merge into compacting states and show that shock formation is an essential mechanism in flows against obstructions. We finally apply the theory of similitude to the design of a projected avalanche protection structure of the Schneefernerhaus at the Zugspitze.

  15. Dense annular flows of granular media

    NASA Astrophysics Data System (ADS)

    de Ryck, Alain; Louisnard, Olivier

    2013-06-01

    Dense granular flows constitute an important topic for geophysics and process engineering. To describe them, a rheology based on the coaxiality between the stress and strain tensors with a Mohr-Coulomb yield criterion has been proposed. We propose here an analytic study of flows in an annular cell, with this rheology. This geometry is relevant for a series of powder rheometers or mixing devices, but the discussion is focused on the split-bottom geometry, for which the internal flow has been investigated by NMR technique. In this case, the full resolution of the velocity and stress fields allow to localize the shear deformations. The theoretical results obtained for the latter are compared with the torque measurements by Dijksman et al. [Phys. Rev. E, 82 (2010) 060301].

  16. Emotional Granularity and Borderline Personality Disorder

    PubMed Central

    Suvak, Michael K.; Litz, Brett T.; Sloan, Denise M.; Zanarini, Mary C.; Barrett, Lisa Feldman; Hofmann, Stefan G.

    2011-01-01

    This study examined the affective dysregulation component of borderline personality disorder (BPD) from an emotional granularity perspective, which refers to the specificity in which one represents emotions. Forty-six female participants meeting criteria for BPD and 51 female control participants without BPD and Axis I pathology completed tasks that assessed the degree to which participants incorporated information about valence (pleasant–unpleasant) and arousal (calm–activated) in their semantic/conceptual representations of emotions and in using labels to represent emotional reactions. As hypothesized, participants with BPD emphasized valence more and arousal less than control participants did when using emotion terms to label their emotional reactions. Implications and future research directions are discussed. PMID:21171723

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Sound pulse broadening in stressed granular media

    NASA Astrophysics Data System (ADS)

    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.

  3. Pulling an intruder from a granular material

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Behringer, R. P.

    2016-11-01

    As a complement to 2D impact experiments, which involves a strongly fluctuating drag force involving collisional momentum transfer from intruder to grains, we consider a controlled 2D pull-out experiments, which is heuristically a reversed version of impact. During the pull-out experiment, a buried intruder is pulled out of a material, starting from rest. In the experiment, the intruder is subject to a gradually increasing upward vertical force, which we increase to the point where the intruder begins to accelerate upwards. To visualize this pulling process, we use 2D photoelastic disks from which circular intruders of different radii are pulled out. We will analyze the dynamics of the intruder and the structures of the force chains inside the granular system, which are captured by a high speed camera. NSF-DMR-1206351, and the William M. Keck Foundation.

  4. Bubbles Rising Through a Soft Granular Material

    NASA Astrophysics Data System (ADS)

    Le Mestre, Robin; MacMinn, Chris; Lee, Sungyon

    2016-11-01

    Bubble migration through a soft granular material involves a strong coupling between the bubble dynamics and the deformation of the material. This is relevant to a variety of natural processes such as gas venting from sediments and gas exsolution from magma. Here, we study this process experimentally by injecting air bubbles into a quasi-2D packing of soft hydrogel beads and measuring the size, speed, and morphology of the bubbles as they rise due to buoyancy. Whereas previous work has focused on deformation resisted by intergranular friction, we focus on the previously inaccessible regime of deformation resisted by elasticity. At low confining stress, the bubbles are irregular and rounded, migrating via local rearrangement. At high confining stress, the bubbles become unstable and branched, migrating via pathway opening. The authors thank The Royal Society for support (International Exchanges Ref IE150885).

  5. 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.

  6. A hadron calorimeter with scintillators parallel to the beam

    NASA Astrophysics Data System (ADS)

    Abramov, V.; Goncharov, P.; Gorin, A.; Gurzhiev, A.; Dyshkant, A.; Evdokimov, V.; Kolosov, V.; Korablev, A.; Korneev, Yu.; Kostritskii, A.; Krinitsyn, A.; Kryshkin, V.; Podstavkov, V.; Polyakov, V.; Shtannikov, A.; Tereschenko, S.; Turchanovich, L.; Zaichenko, A.

    1997-02-01

    A hadron calorimeter in which scintillators are arranged nearly parallel to the incident particle direction and light is collected by optical fibres with WLS, has been built. The iron absorber plates are of the tapered shape to fit a barrel structure of the collider geometry. The performance of the calorimeter studied with hadron beam is presented as a function of tilt angle without and with electromagnetic calorimeter in front of the hadron one.

  7. Accessing the Distribution of Linearly Polarized Gluons in Unpolarized Hadrons

    SciTech Connect

    Boer, Daniel; Brodsky, Stanley J.; Mulders, Piet J.; Pisano, Cristian; /Cagliari U. /INFN, Cagliari

    2011-08-19

    Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos2{phi} asymmetries in heavy quark pair or dijet production in electron-hadron collisions. Future Electron-Ion Collider (EIC) or Large Hadron electron Collider (LHeC) experiments are ideally suited for this purpose. Here we estimate the maximum asymmetries for EIC kinematics.

  8. Quark-hadron phase transition in massive gravity

    NASA Astrophysics Data System (ADS)

    Atazadeh, K.

    2016-11-01

    We study the quark-hadron phase transition in the framework of massive gravity. We show that the modification of the FRW cosmological equations leads to the quark-hadron phase transition in the early massive Universe. Using numerical analysis, we consider that a phase transition based on the chiral symmetry breaking after the electroweak transition, occurred at approximately 10 μs after the Big Bang to convert a plasma of free quarks and gluons into hadrons.

  9. Brazil-nut effect: Size separation of granular particles

    NASA Astrophysics Data System (ADS)

    Möbius, Matthias E.; Lauderdale, Benjamin E.; Nagel, Sidney R.; Jaeger, Heinrich M.

    2001-11-01

    Granular media differ from other materials in their response to stirring or jostling - unlike two-fluid systems, bi-disperse granular mixtures will separate according to particle size when shaken, with large particles rising, a phenomenon termed the 'Brazil-nut effect'. Mounting evidence indicates that differences in particle density affect size separation in mixtures of granular particles. We show here that this density dependence does not follow a steady trend but is non-monotonic and sensitive to background air pressure. Our results indicate that particle density and interstitial air must both be considered in size segregation.

  10. 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.

  11. Drag force scaling for penetration into granular media.

    PubMed

    Katsuragi, Hiroaki; Durian, Douglas J

    2013-05-01

    Impact dynamics is measured for spherical and cylindrical projectiles of many different densities dropped onto a variety non-cohesive granular media. The results are analyzed in terms of the material-dependent scaling of the inertial and frictional drag contributions to the total stopping force. The inertial drag force scales similar to that in fluids, except that it depends on the internal friction coefficient. The frictional drag force scales as the square-root of the density of granular medium and projectile, and hence cannot be explained by the combination of granular hydrostatic pressure and Coulomb friction law. The combined results provide an explanation for the previously observed penetration depth scaling.

  12. Computer simulations of granular materials: the effects of mesoscopic forces

    NASA Astrophysics Data System (ADS)

    Kohring, G. A.

    1994-12-01

    The problem of the relatively small angles of repose reported by computer simulations of granular materials is discussed. It is shown that this problem can be partially understood as resulting from mesoscopic forces which are commonly neglected in the simulations. After including mesoscopic forces, characterized by the easily measurable surface energy, 2D computer simulations indicate that the angle of repose should increase as the size of the granular grains decreases, an effect not seen without mesoscopic forces. The exact magnitude of this effect depends upon the value of the surface energy and the coordination number of the granular pile.

  13. Hydrodynamic modeling of granular flows in a modified Couette cell.

    PubMed

    Jop, Pierre

    2008-03-01

    We present simulations of granular flows in a modified Couette cell, using a continuum model recently proposed for dense granular flows. Based on a friction coefficient, which depends on an inertial number, the model captures the positions of the wide shear bands. We show that a smooth transition in velocity-profile shape occurs when the height of the granular material is increased, leading to a differential rotation of the central part close to the surface. The numerical predictions are in qualitative agreement with previous experimental results. The model provides predictions for the increase of the shear band width when the rotation rate is increased.

  14. Transition from rolling to jamming in thin granular layers.

    PubMed

    Marone, C; Carpenter, B M; Schiffer, P

    2008-12-12

    We study the granular jamming transition for sheared layers of spherical beads ranging in thickness from 1 to 3 times the grain diameter d. As the layer thickness increases slightly above d, the measured friction jumps discontinuously from 0.02 to >0.1, marking the transition from rolling to jamming. Above a critical layer thickness for jamming, the effective granular pressure displays a power law increase with thickness. For thin layers, friction and P increases as the packing fraction decreases near the jamming transition, in contrast to expectations for bulk granular matter.

  15. Some fundamental aspects of the continuumization problem in granular Media

    NASA Astrophysics Data System (ADS)

    Peters, John F.

    The central problem of devising mathematical models of granular materials is how to define a granular medium as a continuum. This paper outlines the elements of a theory that could be incorporated in discrete models such as the Discrete-Element Method, without recourse to a continuum description. It is shown that familiar concepts from continuum mechanics such as stress and strain can be defined for interacting discrete quantities. Established concepts for constitutive equations can likewise be applied to discrete quantities. The key problem is how to define the constitutive response in terms of truncated strain measures that are a practical necessity for analysis of large granular systems.

  16. Microbunched electron cooling for high-energy hadron beams.

    PubMed

    Ratner, D

    2013-08-23

    Electron and stochastic cooling are proven methods for cooling low-energy hadron beams, but at present there is no way of cooling hadrons as they near the TeV scale. In the 1980s, Derbenev suggested that electron instabilities, such as free-electron lasers, could create collective space charge fields strong enough to correct the hadron energies. This Letter presents a variation on Derbenev's electron cooling scheme using the microbunching instability as the amplifier. The large bandwidth of the instability allows for faster cooling of high-density beams. A simple analytical model illustrates the cooling mechanism, and simulations show cooling rates for realistic parameters of the Large Hadron Collider.

  17. Energy-range relations for hadrons in nuclear matter

    NASA Technical Reports Server (NTRS)

    Strugalski, Z.

    1985-01-01

    Range-energy relations for hadrons in nuclear matter exist similarly to the range-energy relations for charged particles in materials. When hadrons of GeV kinetic energies collide with atomic nuclei massive enough, events occur in which incident hadron is stopped completely inside the target nucleus without causing particle production - without pion production in particular. The stoppings are always accompanied by intensive emission of nucleons with kinetic energy from about 20 up to about 400 MeV. It was shown experimentally that the mean number of the emitted nucleons is a measure of the mean path in nuclear matter in nucleons on which the incident hadrons are stopped.

  18. K(s)0 Hadronization Following DIS at CLAS

    SciTech Connect

    K. Hicks, A. Daniel

    2009-10-01

    The hadronization of K{sup 0} particles was measured in semi-inclusive deep inelastic scattering (SIDIS) kinematics for several nuclear targets using the CLAS detector. Multiplicity ratios and Δp{sup 2}{sub T} values were extracted from the data. These results may be compared with similar values for π{sup +} hadronization from CLAS (at the same kinematics) and K{sup +} hadronization from HERMES (at higher energy transfer). The physics goal of these measurements is to understand the space-time evolution as the struck quark becomes a full-blown hadron as it propagates through nuclear matter.

  19. The Brief Life of a Hadron: QCD unquenched

    SciTech Connect

    Pennington, Michael R.

    2015-03-01

    Once upon a time, the picture of hadrons was of mesons made of a quark and an antiquark, and baryons of three quarks. Though hadrons heavier than the ground states inevitably decay by the strong interaction, the successes of the quark model might suggest their decays are a mere perturbation. However, Eef van Beveren, whose career we celebrate here, recognised that decays are an integral part of the life of a hadron. The channels into which they decay are often essential to their very existence. These hold the secrets of strong coupling QCD and teach us the way quarks really build hadrons.

  20. Improved Neutron Scintillators Based on Nanomaterials

    SciTech Connect

    Dennis Friesel, PhD

    2008-06-30

    The development work conducted in this SBIR has so far not supported the premise that using nano-particles in LiFZnS:Ag foils improves their transparency to 420 (or other frequency) light. This conclusion is based solely on the light absorption properties of LiFZnS foils fabricated from nano- and from micro-particles. Furthermore, even for the case of the Gd{sub 2}O{sub 3} foils, the transmission of 420 nm light gained by using nano-particles all but disappears as the foil thickness is increased beyond about 0.2 mm, a practical scintillator thickness. This was not immediately apparent from the preliminary study since no foils thicker than about 0.04 mm were produced. Initially it was believed that the failure to see an improvement by using nano-particles for the LiFZnS foils was caused by the clumping of the particles in Toluene due to the polarity of the ZnS particles. However, we found, much to our surprise, that nano-particle ZnS alone in polystyrene, and in Epoxy, had worse light transmission properties than the micro-particle foils for equivalent thickness and density foils. The neutron detection measurements, while disappointing, are attributable to our inability to procure or fabricate Bulk Doped ZnS nanoparticles. The cause for the failure of nano-particles to improve the scintillation light, and hence improved neutron detection efficiency, is a fundamental one of light scattering within the scintillator. A consequence of PartTec's documentation of this is that several concepts for the fabrication of improved {sup 6}LiFZnS scintillators were formulated that will be the subject of a future SBIR submission.

  1. Hadronic and nuclear interactions in QCD

    SciTech Connect

    Not Available

    1982-01-01

    Despite the evidence that QCD - or something close to it - gives a correct description of the structure of hadrons and their interactions, it seems paradoxical that the theory has thus far had very little impact in nuclear physics. One reason for this is that the application of QCD to distances larger than 1 fm involves coherent, non-perturbative dynamics which is beyond present calculational techniques. For example, in QCD the nuclear force can evidently be ascribed to quark interchange and gluon exchange processes. These, however, are as complicated to analyze from a fundamental point of view as is the analogous covalent bond in molecular physics. Since a detailed description of quark-quark interactions and the structure of hadronic wavefunctions is not yet well-understood in QCD, it is evident that a quantitative first-principle description of the nuclear force will require a great deal of theoretical effort. Another reason for the limited impact of QCD in nuclear physics has been the conventional assumption that nuclear interactions can for the most part be analyzed in terms of an effective meson-nucleon field theory or potential model in isolation from the details of short distance quark and gluon structure of hadrons. These lectures, argue that this view is untenable: in fact, there is no correspondence principle which yields traditional nuclear physics as a rigorous large-distance or non-relativistic limit of QCD dynamics. On the other hand, the distinctions between standard nuclear physics dynamics and QCD at nuclear dimensions are extremely interesting and illuminating for both particle and nuclear physics.

  2. Hadron bubble evolution into the quark sea

    SciTech Connect

    Freese, K. ); Adams, F.C. )

    1990-04-15

    A solution is presented for the evolution of hadron bubbles which nucleate in the quark sea if there is a first-order quark-hadron phase transition at a temperature {ital T}{sub {ital c}} on the order of 100 MeV. We make three assumptions: (1) the dominant mechanism for transport of latent heat is radiative, e.g., neutrinos; (2) the distance between nucleation sites is greater than the neutrino mean free path; and (3) the effects of hydrodynamic flow can be neglected. Bubbles nucleate with a characteristic radius 1 fm/{Delta}, where {Delta} is a dimensionless parameter for the undercooling (we take {Delta}{ge}10{sup {minus}4}, so that the expansion of the Universe can be neglected). We argue that bubbles grow stably and remain spherical until the radius becomes as large as the neutrino mean free path, {ital l}{congruent}10 cm. The growth then becomes diffusion limited and the bubbles become unstable to formation of dendrites, or fingerlike structures, because latent heat can diffuse away more easily from long fingers than from spheres. We study the nonlinear evolution of structure with a geometrical model'' and argue that the hadron bubbles ultimately look like stringy seaweed. The percolation of seaweed-shaped bubbles can leave behind regions of quark phase that are quite small. In fact, one might expect the typical scale to be {ital L}{sub {ital Q}}={ital l}{congruent}10 cm. Protons can easily diffuse out of such small regions (and neutrons back in). Thus, these instabilities can lead to important modifications of inhomogeneous nucleosynthesis, which requires {ital L}{sub {ital Q}}{approx gt}1 m.

  3. High-energy hadron-hadron (dipole-dipole) scattering from lattice QCD

    NASA Astrophysics Data System (ADS)

    Giordano, Matteo; Meggiolaro, Enrico

    2008-10-01

    In this paper the problem of high-energy hadron-hadron (dipole-dipole) scattering is approached (for the first time) from the point of view of lattice QCD, by means of Monte Carlo numerical simulations. In the first part, we give a brief review of how high-energy scattering amplitudes can be reconstructed, using a functional-integral approach, in terms of certain correlation functions of two Wilson loops, and we also briefly recall some relevant analyticity and crossing-symmetry properties of these loop-loop correlation functions, when going from Euclidean to Minkowskian theory. In the second part, we shall see how these (Euclidean) loop-loop correlation functions can be evaluated in lattice QCD, and we shall compare our numerical results with some nonperturbative analytical estimates that appeared in the literature, discussing, in particular, the question of the analytic continuation from Euclidean to Minkowskian theory and its relation to the still unsolved problem of the asymptotic s dependence of the hadron-hadron total cross sections.

  4. Neutron stars: A cosmic hadron physics laboratory

    NASA Technical Reports Server (NTRS)

    Pines, David

    1989-01-01

    A progress report is given on neutron stars as a cosmic hadron physics laboratory. Particular attention is paid to the crustal neutron superfluid, and to the information concerning its properties which may be deduced from observations of pulsar glitches and postglitch behavior. Current observational evidence concerning the softness or stiffness of the high density neutron matter equation of state is reviewed briefly, and the (revolutionary) implications of a confirmation of the existence of a 0.5 ms pulsar at the core of (Supernova) SN1987A are discussed.

  5. The Large Hadron Collider and Grid computing.

    PubMed

    Geddes, Neil

    2012-02-28

    We present a brief history of the beginnings, development and achievements of the worldwide Large Hadron Collider Computing Grid (wLCG). The wLCG is a huge international endeavour, which is itself embedded within, and directly influences, a much broader computing and information technology landscape. It is often impossible to identify true cause and effect, and they may appear very different from the different perspectives (e.g. information technology industry or academic researcher). This account is no different. It represents a personal view of the developments over the last two decades and is therefore inevitably biased towards those things in which the author has been personally involved.

  6. Slepton Pair Production at Hadron Colliders

    NASA Astrophysics Data System (ADS)

    Fuks, B.

    2007-04-01

    In R-parity conserving supersymmetric models, sleptons are produced in pairs at hadron colliders. We show that measurements of the longitudinal single-spin asymmetry at possible polarization upgrades of existing colliders allow for a direct extraction of the slepton mixing angle. A calculation of the transverse-momentum spectrum shows the importance of resummed contributions at next-to-leading logarithmic accuracy in the small and intermediate transverse-momentum regions and little dependence on unphysical scales and non-perturbative contributions.

  7. Black Holes and the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Roy, Arunava

    2011-12-01

    The European Center for Nuclear Research or CERN's Large Hadron Collider (LHC) has caught our attention partly due to the film ``Angels and Demons.'' In the movie, an antimatter bomb attack on the Vatican is foiled by the protagonist. Perhaps just as controversial is the formation of mini black holes (BHs). Recently, the American Physical Society1 website featured an article on BH formation at the LHC.2 This article examines some aspects of mini BHs and explores the possibility of their detection at the LHC.

  8. Oscillating Hadron and Jet Multiplicity Moments

    NASA Astrophysics Data System (ADS)

    Ochs, W.

    2004-01-01

    Recently, the moments of multiplicity distributions in e+e- annihilation and the ratios Hq (cumulant over factorial moments Kq/Fq) have been determined both for the hadronic final state and for jets at variable resolution. These ratios show an oscillatory behaviour as function of q with strong dependence of the amplitude and length of oscillation on the jet resolution parameter ycut. The recent explanation of this phenomenon based on perturbative QCD calculations is discussed.

  9. Quarks and gluons in hadrons and nuclei

    SciTech Connect

    Close, F.E. Tennessee Univ., Knoxville, TN )

    1989-01-01

    These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. 38 refs.

  10. Hadron rapidity spectra within a hybrid model

    NASA Astrophysics Data System (ADS)

    Khvorostukhin, A. S.; Toneev, V. D.

    2017-01-01

    A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.

  11. Photodetectors for the CMS hadron calorimeters

    NASA Astrophysics Data System (ADS)

    Elias, J. E.; CMS Hadron Calorimeter Readout Group

    1997-02-01

    Hadronic energy measurements in the central and end cap regions of the Compact Muon Solenoid (CMS) detector will be made using sampling calorimeter techniques with plastic scintillator tiles as the sensitive layers. Plastic fibers doped with wavelength shifting fluors embedded in each tile are used to extract the scintillation light. Clear plastic wave guide fibers carry the shifted light to photodetectors located on the outer surface of the calorimeter structure. Environmental constraints and physics performance requirements for these photodetectors are presented. Candidate photodetector technologies are discussed, and the hybrid photomultiplier tube technology is identified as most promising.

  12. Partial restoration of chiral symmetry inside hadrons

    SciTech Connect

    Iritani, Takumi; Cossu, Guido; Hashimoto, Shoji

    2016-01-22

    We investigate the spatial distribution of the chiral condensate around static color sources for both quark-antiquark and three-quark systems. In the QCD vacuum a tube-like structure of chromo fields appears between color sources, which leads to a linearly confining potential. We show that the magnitude of the condensate is reduced inside the flux-tube, which suggests that chiral symmetry is partially restored inside the hadrons. By using a static baryon source in a periodic box as a model of the nuclear matter, we estimate the restoration of chiral symmetry with finite baryon number density.

  13. Uniformity requirements in CMS hadron calorimetry

    SciTech Connect

    Green, D.

    1996-02-01

    Practical considerations of calorimeter systems require a specification of the allowed manufacturing tolerances. The tightness of these requirements directly makes an impact on the assembly costs of the calorimeter. For that reason, a precise and well defined set of criteria is mandatory. In addition, the intrinsic limitations of hadron calorimetry define the level of accuracy needed in the manufacture of such devices. Therefore, considerations of the limitations on energy measurement accuracy due to Physics should define the needed level of effort to produce a uniform calorimetric device.

  14. Signatures for Majorana neutrinos at hadron colliders.

    PubMed

    Han, Tao; Zhang, Bin

    2006-10-27

    The Majorana nature of neutrinos may only be experimentally verified via lepton-number violating processes involving charged leptons. We explore the Delta L = 2 like-sign dilepton production at hadron colliders to search for signals of Majorana neutrinos. We find significant sensitivity for resonant production of a Majorana neutrino in the mass range of 10-80 GeV at the current run of the Tevatron with 2 fb(-1) integrated luminosity and in the range of 10-400 GeV at the CERN LHC with 100 fb(-1).

  15. Charmless b-hadrons decays at CDF

    SciTech Connect

    Morello, Michael Joseph; /Pisa U. /INFN, Pisa

    2008-10-01

    We present CDF results on the branching fractions and time-integrated direct CP asymmetries for Bd, Bs and Lb decay modes into pairs of charmless charged hadrons (pions, kaons and protons). The data-set for these measurements amounts to 1fb{sup -1} of p{bar p} collisions at a center of mass energy 1.96TeV. We report on the first observation of the Bs->Kpi, Lb-ppi and Lb->pK decay modes and on the measurement of their branching fractions and direct CP asymmetries.

  16. Hadronic and Semileptonic B Decays at Babar

    NASA Astrophysics Data System (ADS)

    Rama, M.

    2003-02-01

    We present a review of a selection of hadronic and semileptonic B decays reconstructed with the BaBar detector on a data sample of 22.7 million Bbar B pairs. Measurements of the exclusive branching ratios of B0 → D*+D*- and B -> D{( * )} ˜ D{( * )} K and the ratio of branching fractions of B± → J/ψh± and B- → D0 h- (h = π, K) decays are presented. Measurements of the inclusive semileptonic branching fractions of charged and neutral B mesons are described and a measurement of |Vcb| is presented.

  17. QCD SPIN PHYSICS IN HADRONIC INTERACTIONS.

    SciTech Connect

    VOGELSANG,W.

    2007-06-19

    We discuss spin phenomena in high-energy hadronic scattering, with a particular emphasis on the spin physics program now underway at the first polarized proton-proton collider, RHIC. Experiments at RHIC unravel the spin structure of the nucleon in new ways. Prime goals are to determine the contribution of gluon spins to the proton spin, to elucidate the flavor structure of quark and antiquark polarizations in the nucleon, and to help clarify the origin of transverse-spin phenomena in QCD. These lectures describe some aspects of this program and of the associated physics.

  18. Di-Hadron Angular Correlation Dependence on Leading Hadron Identity in Relativistic Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Kauder, Kolja

    A unique state of matter is created in ultra-relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), the Quark Gluon Plasma (QGP). It displays the properties of a near-perfect liquid of quarks and gluons (partons) interacting collectively via the strong force. Properties of this medium can be explored using high-energy probes created in the form of back-to-back pairs (jets) in hard scatterings. A distinct feature of the QGP is jet quenching, which describes the large energy loss of such probes observed in measurements of hadron distributions in head-on heavy ion collisions. A more differential measurement of jet quenching is achieved using di-hadron correlations, where relative angular distributions are studied with respect to a leading (high energy) "trigger" hadron. Two striking features found in di-hadron correlations are the emergence of a long-range plateau on the near-side (at small relative azimuth), the so-called "ridge", and a broadening and deformation of the away-side, back to back with the trigger. Using 200 GeV central gold-gold and minimum bias deuteron-gold collision data collected by the STAR detector at RHIC, a systematic study of the dependence of di-hadron correlation structures on the identity of the trigger particle is carried out in this work by statistically separating pion from non-pion (i.e. proton and kaon) triggers, offering new insights into the hadronization mechanisms in the QGP. The jet-like yield at small relative angles is found enhanced for leading pions in Au+Au data with respect to the d+Au reference, while leading non-pions (protons and kaons) do not elicit such an enhancement. These findings are discussed within the context of quark recombination. At large angles, the correlated yield is significantly higher for leading non-pions than pions. Parameters extracted from two-dimensional model fits are used to test consistency with the constituent quark scaling assumptions

  19. 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...

  20. The propagation of blast pulses through dampened granular media

    NASA Astrophysics Data System (ADS)

    Badham, Henry; Chalmers, Max; Nguyen, Thuy-Tien Ngoc; Proud, William Graham

    2017-01-01

    The propagation of stress through granular and dampened granular material has been reported previously, the addition of significant amounts of liquid in granular beds causes the mechanism of transmission of blast from one of percolation through the bed pores to one of stress transmission through the granules of the bed. It has been shown, however, that limited amounts liquid can retard propagation within blast-loaded beds by approximately an order of magnitude. This paper presents data on percolation through dampened granular beds using a shock tube as the pressure driver. The effect of particle shape and size was investigated using angular grains of quartz sand as well as smooth glass microspheres. The effect of addition of small amounts of liquids is presented.

  1. 76 FR 8774 - Granular Polytetrafluoroethylene Resin From Japan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Granular Polytetrafluoroethylene Resin From Japan AGENCY: United States International Trade... polytetrafluoroethylene resin from Japan would be likely to lead to continuation or recurrence of material injury....

  2. Granular Microbial Habitats Built from Iron Sulfides: Alternative Microbial Lifestyles?

    NASA Astrophysics Data System (ADS)

    Schieber, J.

    2005-03-01

    Concentrically zoned pyrite grains grew as granular microbial colonies. They stayed in the surface layer during long history of reworking and accretion and consist of marcasite and pyrite cortices with sulfide mineralized microbial remains.

  3. 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.

  4. 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.

  5. 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.

  6. Bifurcation and nonlinear behavior of compartmentalized granular gases

    NASA Astrophysics Data System (ADS)

    Hou, Meiying; Liu, Rui; Li, Yinchang; Zhang, Yin; Shah, Sajjad Hussain

    2014-12-01

    Different from the molecular gas, clustering is a most commonly observed feature of the granular gas. A review is given of our previous work on the clustering, especially the oscillatory clustering for shaken fluidized granular matter in connected compartments, as examples for pattern formation and bifurcations in far from equilibrium systems. Flux model is presented and discussed for mono-disperse and bi-disperse granular systems. Comparison of the flux model with simulation results is given. They show reasonably well agreements. Besides the homogeneous (HOM), segregation (SEG), and oscillatory (OSC) states, two new stationary states (d-OSC and s-HOM) in the bi-disperse granular system are predicted by our simulation. In our recent work these two new states are observed experimentally, and their flow diagrams are obtained based on the flux model. The transition from degenerate oscillation state to oscillation state demonstrates a homoclinic gluing bifurcation.

  7. 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.

  8. 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

  9. Charged kaon and proton production in B-hadron decays

    NASA Astrophysics Data System (ADS)

    Tegenfeldt, Fredrik Per

    The production of charged kaons and protons in B-hadron decays has been measured in e+e- annihilations at centre-of-mass energies corresponding to the Z0 mass. In total 1.6 million hadronic Z0 decays were analysed, corresponding to about 690000 B-hadron decays. They were collected using the DELPHI detector at the LEP collider at CERN during 1994 and 1995. Events containing B-hadron decays were identified using special characteristics of the B-hadron decay topology. In particular, the long lifetime of the B-hadron leads to decay vertices significantly displaced relative the interaction point. These so called secondary vertices were reconstructed using a powerful micro vertex detector. In order to discriminate B-hadron decay products from fragmentation tracks, a method was used where the impact parameter measured by the vertex detector was employed as a discriminating variable. The tracks were thus divided into two classes, one compatible with the interaction point and the other compatible with a secondary vertex. An unfolding method was used to extract the true B-hadron decay tracks from the two classes. Charged kaons and protons were identified using the Ring Imaging CHerenkov (RICH) detector and corrected for misidentification using an efficiency matrix. The analysis resulted in charged kaon and proton spectra from B-hadron decays, including previously unmeasured momentum regions. Integrating the spectra yielded the following multiplicities n(B- hadron-->K+/- X)=0.683+/-0.021(stat) +/-0.017(syst) n(B- hadron-->p/p X)=0.127+/-0.013(stat) +/-0.019(syst) where the proton multiplicity does not include Λ baryon decay products.

  10. [Endobronchial granular cell tumor - what approach to take].

    PubMed

    Rego, Ana; Amado, Joana; Esteves, Idália; Almeida, José; Furtado, Antónia; Couceiro, António; Moura e Sá, João

    2006-01-01

    Granular cell tumor is a mesenchymal neoplasm almost always benign, with tendency to recurrence. Although it is more frequent in in the head and neck it has been described in almost all areas of the body. Its occurrence in the lung is extremely rare. The authors describe two cases of endobronchial granular cell tumours, discuss the particularities of this pathology as well as the treatment options, with particular attention to the use of endobronchial excision and criotherapy.

  11. Energy-Consistent Multiscale Algorithms for Granular Flows

    DTIC Science & Technology

    2014-08-07

    the behavior of granular materials under extreme avalanche flow. In the area of algorithmic development at the grain scale, we have successfully...flow; iii) the development of experimental techniques and approaches to model the behavior of granular materials under extreme avalanche flow. In the... avalanches . Status/Progress In this grant, we have focused mainly in making progress within three (3) areas of mayor interest: (1) a new simulation

  12. 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.

  13. Thermal creep of granular breeder materials in fusion blankets

    NASA Astrophysics Data System (ADS)

    Bühler, L.; Reimann, J.

    2002-12-01

    Continuum models for granular materials in fusion blankets are efficient tools for modeling of the nonlinear elastic behavior of pebble beds, granular particle flow caused by shear, volume compaction and hardening. The present paper describes how the material models used in finite element analyses can be extended in order to account additionally for thermally activated creep. The derived material model gives results which are in reasonable accordance with experimental data for pebble beds.

  14. Future directions in particle and nuclear physics at multi-GeV hadron beam facilities

    SciTech Connect

    Geesaman, D.F.

    1993-11-01

    This report contains papers on the following topics in particle and nuclear physics: hadron dynamics; lepton physics; spin physics; hadron and nuclear spectroscopy; hadronic weak interactions; and Eta physics. These papers have been indexed separately elsewhere.

  15. Granular materials: constitutive equations and strain localization

    NASA Astrophysics Data System (ADS)

    Anand, L.; Gu, C.

    2000-08-01

    Strain localization into shear bands is commonly observed in natural soil masses, as well as in human-built embankments, footings, retaining walls and other geotechnical structures. Numerical predictions for the process of shear band formation are critically dependent on the constitutive equations employed. In this paper, the plane strain "double-shearing" constitutive model (e.g., Spencer, A.J.M., 1964. A theory of the kinematics of ideal soils under plane strain conditions. Journal of the Mechanics and Physics of Solids 12, 337-351; Spencer, A.J.M., 1982, Deformation of ideal granular materials. In: Hopkins, H.G., Sewell, M.J. (Eds.), Mechanics of Solids. Pergamon Press, Oxford and New York, pp. 607-652; Mehrabadi, M.M., Cowin, S.C., 1978. Initial planar deformation of dilatant granular materials. Journal of the Mechanics and Physics of Solids 26, 269-284; Nemat-Nasser, S., Mehrabadi, M.M., Iwakuma, T. 1981. On certain macroscopic and microscopic aspects of plastic flow of ductile materials. In: Nemat-Nasser, S. (Ed.), Three-dimensional Constitutive Relations and Ductile Fracture. North-Holland, Amsterdam, pp. 157-172; Anand, L., 1983. Plane deformations of ideal granular materials. Journal of the Mechanics and Physics of Solids 31, 105-122) is generalized to three dimensions including the effects of elastic deformation and pre-peak behavior. The constitutive model is implemented in a finite element program and is used to predict the formation of shear bands in plane strain compression, and plane strain cylindrical cavity expansion. The predictions from the model are shown to be in good quantitative agreement with the recent experiments of Han, C., Drescher, A., (1993. Shear bands in biaxial tests on dry coarse sand. Soils and Foundations 33, 118-132) and Alsiny, H., Vardoulakis, I., Drescher, A., (1992. Deformation localization in cavity inflation experiments on dry sand. Geotechnique 42, 395-410) on a dry sand. The constitutive model is also used to predict the

  16. Elementary and brief introduction of hadronic chemistry

    NASA Astrophysics Data System (ADS)

    Tangde, Vijay M.

    2013-10-01

    The discipline, today known as Quantum Chemistry for atomic and subatomic level interactions has no doubt made a significant historical contributions to the society. Despite of its significant achievements, quantum chemistry is also known for its widespread denial of insufficiencies it inherits. An Italian-American Scientist Professor Ruggero Maria Santilli during his more than five decades of dedicated and sustained research has denounced the fact that quantum chemistry is mostly based on mere nomenclatures without any quantitative scientific contents. Professor R M Santilli first formulated the iso-, geno- and hyper-mathematics [1-4] that helped in understanding numerous diversified problems and removing inadequacies in most of the established and celebrated theories of 20th century physics and chemistry. This involves the isotopic, genotopic, etc. lifting of Lie algebra that generated Lie admissible mathematics to properly describe irreversible processes. The studies on Hadronic Mechanics in general and chemistry in particular based on Santilli's mathematics[3-5] for the first time has removed the very fundamental limitations of quantum chemistry [2, 6-8]. In the present discussion, we have briefly reviewed the conceptual foundations of Hadronic Chemistry that imparts the completeness to the Quantum Chemistry via an addition of effects at distances of the order of 1 fm (only) which are assumed to be Non-linear, Non-local, Non-potential, Non-hamiltonian and thus Non-unitary and its application in development of a new chemical species called Magnecules.

  17. Hadron production measurements for neutrino physics

    SciTech Connect

    Panman, Jaap

    2008-02-21

    One of the limiting factors for the precision of neutrino oscillation experiments is the uncertainty in the composition and spectrum of the neutrino flux. Recently, dedicated hadron production experiments have been taking data and are being planned to supply measurements which can significantly reduce these uncertainties. The HARP experiment has presented results on the measurements of the double-differential production cross-section of charged pions in proton interactions with beryllium, carbon, aluminium, copper, tin, tantalum and lead targets. These results are relevant for a detailed understanding of neutrino flux in accelerator neutrino experiments K2K (p-Al data) and MiniBooNE/SciBooNE (p-Be data), for a better prediction of atmospheric neutrino fluxes (p-C, {pi}{sup +}-C and {pi}{sup -}-C data) as well as for a systematic improvement of hadron production models. The E910 experiment at BNL has recently published their p-Be data. NA49 has measured pion production spectra in p-C interactions and a new experiment, NA61, is starting to take data using essentially the same detector. NA61 plans to measure production spectra for the T2K experiment and for the calculation of extended air showers. MIPP has taken data with a copy of the NuMI target and is progressing in the analysis of these data. An upgrade of the readout of this experiment can greatly increase its potential.

  18. Mass reach scaling for future hadron colliders

    NASA Astrophysics Data System (ADS)

    Rizzo, Thomas G.

    2015-04-01

    The primary goal of any future hadron collider is to discover new physics (NP) associated with a high mass scale, , beyond the range of the LHC. In order to maintain the same relative mass reach for rate-limited NP, , as increases, Richter recently reminded us that the required integrated luminosity obtainable at future hadron colliders (FHC) must grow rapidly, , in the limit of naive scaling. This would imply, e.g., a 50-fold increase in the required integrated luminosity when going from the 14 TeV LHC to a FHC with TeV, an increase that would prove quite challenging on many different fronts. In this paper we point out, due to the scaling violations associated with the evolution of the parton density functions (PDFs) and the running of the strong coupling, , that the actual luminosity necessary in order to maintain any fixed value of the relative mass reach is somewhat greater than this scaling result indicates. However, the actual values of the required luminosity scaling are found to be dependent upon the detailed nature of the NP being considered. Here we elucidate this point explicitly by employing several specific benchmark examples of possible NP scenarios and briefly discuss the (relatively weak) search impact in each case if these luminosity goals are not met.

  19. Strong interaction physics from hadronic atoms

    NASA Astrophysics Data System (ADS)

    Batty, C. J.; Friedman, E.; Gal, A.

    1997-08-01

    Hadronic atoms provide a unique laboratory for studying strong interactions and nuclear medium effects at zero kinetic energy. Previous results from analyses of strong-interaction data consisting of level shifts, widths and yields in π-, K -, p¯ and ∑ - atoms are reviewed. Recent results from fits to comprehensive sets of data in terms of density-dependent optical potentials that respect the low-density limit, where the interaction tends to the free hadron nucleon value, are discussed. The importance of using realistic nuclear density distributions is highlighted. The introduction of density dependence in most cases significantly improves the fit to the data and leads to some novel results. For K - atoms, a substantial attraction of order 200 MeV in nuclear matter is suggested, with interesting repercussions for K¯ condensation and the evolution of strangeness in high-density stars. For p¯ atoms it is found that a reasonable p-wave strength can be accommodated in the fitted optical potential, in agreement with the energy dependence observed for some low-energy p¯N reactions. For ∑ - atoms, the fitted potential becomes repulsive inside the nucleus, implying that Σ hyperons generally do not bind in nuclei in agreement with recent measurements. This repulsion significantly affects calculated masses of neutron stars.

  20. Hadronic Lorentz violation in chiral perturbation theory

    NASA Astrophysics Data System (ADS)

    Kamand, Rasha; Altschul, Brett; Schindler, Matthias R.

    2017-03-01

    Any possible Lorentz violation in the hadron sector must be tied to Lorentz violation at the underlying quark level. The relationships between the theories at these two levels are studied using chiral perturbation theory. Starting from a two-flavor quark theory that includes dimension-4 Lorentz-violation operators, the effective Lagrangians are derived for both pions and nucleons, with novel terms appearing in both sectors. Since the Lorentz-violation coefficients for nucleons and pions are all related to a single set of underlying quark coefficients, one can compare the sensitivity of different types of experiments. Our analysis shows that atomic physics experiments currently provide constraints on the quark parameters that are stronger by about 10 orders of magnitude than astrophysical experiments with relativistic pions. Alternatively, it is possible to place approximate bounds on pion Lorentz violation using only proton and neutron observations. Under the assumption that the Lorentz-violating operators considered here are the only ones contributing to the relevant observables and taking the currently unknown hadronic low-energy constants to be of natural size, the resulting estimated bounds on four pion parameters are at the 10-23 level, representing improvements of 10 orders of magnitude.

  1. Diffractive hadron production at ultrahigh energies

    NASA Astrophysics Data System (ADS)

    Anisovich, V. V.; Matveev, M. A.; Nikonov, V. A.

    2015-03-01

    Diffractive production is considered in the ultrahigh energy region where pomeron exchange amplitudes are transformed into black disk ones due to rescattering corrections. The corresponding corrections in hadron reactions h1 + h3 → h1 + h2 + h3 with small momenta transferred (q2{1-> 1} ˜ m2/ln;2s, q2{3-> 3} ˜ m2/ln;2s) are calculated in terms of the K-matrix technique modified for ultrahigh energies. Small values of the momenta transferred are crucial for introducing equations for amplitudes. The three-body equation for hadron diffractive production reaction h1 + h3 → h1 + h2 + h3 is written and solved precisely in the eikonal approach. In the black disk regime final state scattering processes do not change the shapes of amplitudes principally but dump amplitudes by a factor 1/4; initial state rescatterings result in additional factor 1/2. In the resonant disk regime initial and final state scatterings damp strongly the production amplitude that corresponds to σinel/σtot → 0 at √ {s}->∞ in this mode.

  2. Growth and luminescent properties of scintillators based on the single crystalline films of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce garnet

    SciTech Connect

    Zorenko, Yu; Gorbenko, V.; Vasylkiv, Ja; Zelenyj, A.; Fedorov, A.; Kucerkova, R.; Mares, J.A.; Nikl, M.; Bilski, P.; Twardak, A.

    2015-04-15

    Highlights: • Single crystalline films of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12} garnets at x = 0 ÷ 3.0 were grown by LPE method onto YAG substrates. • Lattice constant of Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12}:Ce film and the misfit m between films and YAG substrate changed linearly with increasing of Gd content. • Effective Gd{sup 3+}–Ce{sup 3+} energy transfer occurs in the Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce films. • Best scintillation light yield is observed in the Lu{sub 3}Al{sub 5}O{sub 12}:Ce and Lu{sub 2.4}Gd{sub 0.6}Al{sub 5}O{sub 12}:Ce films. • Increase of the Gd content in x = 1.5–2.5 range results in decreasing the scintillation LY of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce films. - Abstract: The work is related to the growth of scintillators based on the single crystalline films (SCF) of Ce{sup 3+} doped Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12} mixed rare-earth garnets by Liquid Phase Epitaxy (LPE) method. We have shown, that full set of Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12} SCFs with x values ranging from 0 to 3.0 can be successfully crystallized by the LPE method onto Y{sub 3}Al{sub 5}O{sub 12} (YAG) substrates from the melt-solutions based on PbO-B{sub 2}O{sub 3} flux. The absorption, X-ray excited luminescence, photoluminescence, thermoluminescence and light yield measurements, the latter under excitation by α-particles of {sup 239}Pu and {sup 241}Am radioisotopes, were applied for their characterization.

  3. Collapse of granular-liquid mixtures over rigid, inclined beds.

    PubMed

    Berzi, D; Bossi, F C; Larcan, E

    2012-05-01

    This work deals with the propagation of granular-liquid waves over rigid beds, originated by the sudden removal of a sluice gate in a rectangular, inclined flume. In particular, we experimentally investigate the role of the initial volume ratio of granular material-monodispersed plastic cylinders-to water, the flume width, and the bed roughness on the time evolution of the granular front. Due to the presence of the interstitial liquid, we observed previously unreported types of collapse: (i) discontinuous flows, where the granular material stops after an initial spreading, and then flows again when the liquid, initially slower than the particles, reaches the front and remobilizes it; (ii) flows evolving into uniformly progressive waves at an angle of inclination of the flume well below the angle of repose of the dry granular material. We also noticed an unusual influence of the lateral confinement on the wave propagation. Indeed, the constant front velocity in the uniformly progressive state decreases when the channel width increases. We claim that the latter observation and the presence of discontinuous flows, strongly support the idea that only two-phase, stratified mathematical models can predict the behavior of unsteady, granular-liquid mixtures at high concentration, such as debris flows.

  4. Flow of Dense Granular Media; A Peculiar Liquid

    NASA Astrophysics Data System (ADS)

    Pouliquen, Olivier

    2007-11-01

    Rice flowing out of a silo, rocks tumbling down a slope, sand avalanching on a dune, are examples of simple granular flows. Their description still represents a challenge due to the lack of constitutive laws able to describe the rich phenomenology observed with granular materials. However, the numerous experiments and simulations carried out during the last ten years have given keys for a better understanding. This talk will review the general properties of granular flows, before focusing on the dense flow regime where granular media flow like a liquid. In this regime, simple constitutive laws can be proposed, in which the granular fluid is described as a peculiar visco-plastic liquid. This talk will show that this approach gives quantitative predictions in several configurations, providing a relevant framework for adressing granular hydrodynamic problems. The second part of this presentation will discuss the limits of this approach, the important open problems, and the consequences of this development for the more complex case of mixture of grains and fluid. This work has been done with Pierre Jop, Yoel Forterre and Mickael Paihla.

  5. Experimental tests of a statistical mechanics of static granular media

    NASA Astrophysics Data System (ADS)

    Schr"Oter, Matthias

    2005-11-01

    In 1989 Edwards and Oakeshott proposed a statistical mechanics theory of static granular materials described by a temperature-like state variable named compactivity [1]. We have made the first measurement of the compactivity of a granular material [2]. We have examined a granular column driven by flow pulses and have found that the system explores its phase space of mechanically stable configurations in a history-independent way. The system quickly approaches a steady state; the volume fluctuations about this steady state are Gaussian. The mean volume fraction can be varied by changing the flow rate of the pulses. We calculate the compactivity from the standard deviation of the volume fluctuations [3]. This talk will address the following two questions: (a) Are compactivity values measured with our ``thermometer'' different from values one might measure with a ``thermometer'' based on the grain volume distribution [4]? (b) Can compactivity be a control parameter of granular systems, for example, in size segregation in binary granular mixtures? [1] Edwards and Oakeshott, Physica A 157, 1080 (1989). [2] Schr"oter, Goldman, and Swinney, Phys. Rev. E 71, 030301 (2005). [3] Nowak, Knight, Ben-Naim, Jaeger, and Nagel, Phys. Rev. E 57, 1971 (1988). [4] Edwards, Bruji'c, and Makse, in Unifying Concepts in Granular Media and Glasses, edited by Coniglio et al. (Elsevier, Amsterdam, 2004)

  6. 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.

  7. 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

  8. Simulating granular materials by energy minimization

    NASA Astrophysics Data System (ADS)

    Krijgsman, D.; Luding, S.

    2016-11-01

    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

  9. Search For Hadronic Axions Emitted From The Sun

    SciTech Connect

    Ljubicic, A.; Kekez, D.; Krecak, Z.

    2007-10-26

    We made a search for hadronic axions, which could be emitted from the Sun in the axiobremsstrahlung process and absorbed in the HPGe detector by axioelectric effect. An upper limit on hadronic axion mass of 100 eV is obtained at the 95% confidence level.

  10. Using analytic continuation for the hadronic vacuum polarization computation

    SciTech Connect

    Feng, Xu; Hashimoto, Shoji; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; B, Renner Dru

    2014-11-01

    We present two examples of applications of the analytic continuation method for computing the hadronic vacuum polarization function in space- and time-like momentum regions. These examples are the Adler function and the leading order hadronic contribution to the muon anomalous magnetic moment. We comment on the feasibility of the analytic continuation method and provide an outlook for possible further applications.

  11. Muon g-2 and Hadronic Vacuum Polarization: Recent Developments

    NASA Astrophysics Data System (ADS)

    Eidelman, Simon

    2016-04-01

    We discuss various experiments on e+e- annihilation into hadrons relevant to the problem of the muon anomalous magnetic moment. They include a status of the ISR measurements of the e+e- → π+π- as well as studies of numerous hadronic final states in experiments with the CMD-3 and SND detectors at the VEPP-2000 e+e- collider.

  12. Hadron physics at the new CW electron accelerators

    SciTech Connect

    Burkert, V.D.

    1990-01-01

    Major trends of the physics program related to the study of hadron structure and hadron spectroscopy at the new high current, high duty cycle electron machines are discussed. It is concluded that planned experiments at these machines may have important impact on our understanding of the strong interaction by studying the internal structure and spectroscopy of the nucleon and lower mass hyperon states.

  13. Preliminary results of the Gas Electron Multiplier (GEM) as real-time beam monitor in hadron therapy

    NASA Astrophysics Data System (ADS)

    Aza, E.; Ciocca, M.; Murtas, F.; Puddu, S.; Pullia, M.; Silari, M.

    2017-01-01

    The use of proton and carbon ion beams in cancer therapy (also known as hadron therapy) is progressively growing worldwide due to their improved dose distributions, sparing of healthy tissues and (for carbon ions) increased radiobiological effectiveness especially for radio-resistant tumours. Strict Quality Assurance (QA) protocols need to be followed for guaranteeing the clinical beam specifications. The aim of this study was to assess the performance of a gaseous detector based on the Gas Electron Multiplier (GEM) technology for measuring the beam spot dimensions and the homogeneity of the scanned irradiation field, which are daily QA tasks commonly performed using radiochromic films. Measurements performed at the National Centre for Oncological Hadron Therapy (CNAO) in Pavia (Italy) showed that the detector is able to monitor the 2D beam image on-line with a pad granularity of 2 mm and a response proportional to the number of delivered particles. The dose homogeneity was measured with low deviation from the results obtained with radiochromic films.

  14. Exclusive processes and the fundamental structure of hadrons

    SciTech Connect

    Brodsky, Stanley J.

    2015-01-20

    I review the historical development of QCD predictions for exclusive hadronic processes, beginning with constituent counting rules and the quark interchange mechanism, phenomena which gave early validation for the quark structure of hadrons. The subsequent development of pQCD factorization theorems for hard exclusive amplitudes and the development of evolution equations for the hadron distribution amplitudes provided a rigorous framework for calculating hadronic form factors and hard scattering exclusive scattering processes at high momentum transfer. I also give a brief introduction to the field of "light-front holography" and the insights it brings to quark confinement, the behavior of the QCD coupling in the nonperturbative domain, as well as hadron spectroscopy and the dynamics of exclusive processes.

  15. Exclusive processes and the fundamental structure of hadrons

    DOE PAGES

    Brodsky, Stanley J.

    2015-01-20

    I review the historical development of QCD predictions for exclusive hadronic processes, beginning with constituent counting rules and the quark interchange mechanism, phenomena which gave early validation for the quark structure of hadrons. The subsequent development of pQCD factorization theorems for hard exclusive amplitudes and the development of evolution equations for the hadron distribution amplitudes provided a rigorous framework for calculating hadronic form factors and hard scattering exclusive scattering processes at high momentum transfer. I also give a brief introduction to the field of "light-front holography" and the insights it brings to quark confinement, the behavior of the QCD couplingmore » in the nonperturbative domain, as well as hadron spectroscopy and the dynamics of exclusive processes.« less

  16. Reduction of bromate by granular activated carbon

    SciTech Connect

    Kirisits, M.J.; Snoeyink, V.L.; Kruithof, J.C.

    1998-07-01

    Ozonation of waters containing bromide can lead to the formation of bromate, a probable human carcinogen. Since bromate will be regulated at 10 {micro}g/L by the Stage 1 Disinfectants/Disinfection By-Products Rule, there is considerable interest in finding a suitable method of bromate reduction. Granular activated carbon (GAC) can be used to chemically reduce bromate to bromide, but interference from organic matter and anions present in natural water render this process inefficient. In an effort to improve bromate reduction by GAC, several modifications were made to the GAC filtration process. The use of a biologically active carbon (BAC) filter ahead of a fresh GAC filter with and without preozonation, to remove the biodegradable organic matter, did not substantially improve the bromate removal of the GAC filter. The use of the BAC filter for biological bromate reduction proved to be the most encouraging experiment. By lowering the dissolved oxygen in the influent to the BAC from 8.0 mg/L to 2.0 mg/L, the percent bromate removal increased from 42% to 61%.

  17. Granular media filtration: old process, new thoughts.

    PubMed

    Lawler, D F; Nason, J A

    2006-01-01

    The design of granular media filters has evolved over many years so that modern filters have larger media sizes and higher filtration velocities than in earlier times. The fundamental understanding of filtration has also improved over time, with current models that account reasonably for all characteristics of the media, the suspension and the filter operation. The methodology for design, however, has not kept pace with these improvements; current designs are based on pilot plants, past experience, or a simple guideline (the ratio of the bed depth to media grain size). We propose that design should be based universally on a characteristic removal length, with the provision of a bed depth that is some multiple of that characteristic length. This characteristic removal length is calculated using the most recent (and most complete) fundamental model and is based on the particle size with the minimum removal efficiency in a filter. The multiple of the characteristic length that yields the required bed depth has been calibrated to existing, successful filters.

  18. Penetration of projectiles into granular targets

    NASA Astrophysics Data System (ADS)

    Ruiz-Suárez, J. C.

    2013-06-01

    Energetic collisions of subatomic particles with fixed or moving targets have been very valuable to penetrate into the mysteries of nature. But the mysteries are quite intriguing when projectiles and targets are macroscopically immense. We know that countless debris wandering in space impacted (and still do) large asteroids, moons and planets; and that millions of craters on their surfaces are traces of such collisions. By classifying and studying the morphology of such craters, geologists and astrophysicists obtain important clues to understand the origin and evolution of the Solar System. This review surveys knowledge about crater phenomena in the planetary science context, avoiding detailed descriptions already found in excellent papers on the subject. Then, it examines the most important results reported in the literature related to impact and penetration phenomena in granular targets obtained by doing simple experiments. The main goal is to discern whether both schools, one that takes into account the right ingredients (planetary bodies and very high energies) but cannot physically reproduce the collisions, and the other that easily carries out the collisions but uses laboratory ingredients (small projectiles and low energies), can arrive at a synergistic intersection point.

  19. Phase diagram for inertial granular flows

    NASA Astrophysics Data System (ADS)

    DeGiuli, E.; McElwaine, J. N.; Wyart, M.

    2016-07-01

    Flows of hard granular materials depend strongly on the interparticle friction coefficient μp and on the inertial number I , which characterizes proximity to the jamming transition where flow stops. Guided by numerical simulations, we derive the phase diagram of dense inertial flow of spherical particles, finding three regimes for 10-4≲I ≲10-1 : frictionless, frictional sliding, and rolling. These are distinguished by the dominant means of energy dissipation, changing from collisional to sliding friction, and back to collisional, as μp increases from zero at constant I . The three regimes differ in their kinetics and rheology; in particular, the velocity fluctuations and the stress ratio both display nonmonotonic behavior with μp, corresponding to transitions between the three regimes of flow. We rationalize the phase boundaries between these regimes, show that energy balance yields scaling relations between microscopic properties in each of them, and derive the strain scale at which particles lose memory of their velocity. For the frictional sliding regime most relevant experimentally, we find for I ≥10-2.5 that the growth of the macroscopic friction μ (I ) with I is induced by an increase of collisional dissipation. This implies in that range that μ (I ) -μ (0 ) ˜I1 -2 b , where b ≈0.2 is an exponent that characterizes both the dimensionless velocity fluctuations L ˜I-b and the density of sliding contacts χ ˜Ib .

  20. Saturn's ring "propellers": gravitational or granular?

    NASA Astrophysics Data System (ADS)

    Burns, Joseph A.; Lawney, B. P.; Jenkins, J. T.

    2010-05-01

    Propeller-shaped brightness features observed in Saturn's A ring are density disturbances, usually thought to be induced by gravity. Embedded masses larger than tens of meters disturb the smooth Keplerian shear of typical small ring particles (cm to m in radius) sufficiently to be visible in Cassini images. Instead we investigate whether propeller formation could be solely a collisional phenomenon involving the collisional energy dissipation, moon-to-particle size ratio, and the initial areal fractional coverage. Our two-dimensional, event-driven molecular dynamics simulation, which is carried out within Hill's equations and ignores gravity between the moon and the particles, develops "propeller-like” structures. We argue that the relatively low agitation and density of ring material is responsible for a low sound speed, resulting in predominantly supersonic flow of ring particles relative to the moon. In this framework, "propellers” are viewed as the locus of a granular shock, analogous to shocks in compressible gases, across which the ring material experiences significant changes in density, velocity, pressure, and the analog of temperature. We model these changes analytically and through numerical simulations to determine the propeller's size. We anticipate that inferences about the embedded objects will change with this different model.