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  • 1.
    Almqvist, Nils
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Fredriksson, Sverker
    Backman, Lars
    Imaging human erythrocyte spectrin with atomic force microscopy1994In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 25, no 3, 227-232 p.Article in journal (Refereed)
    Abstract [en]

    Isolated spectrin covalently attached to a surface in a liquid environment as well as dried on mica has been studied with a contact-mode atomic force microscope. Both pyramidal and conical-type cantilever tip facets were used in the AFM. Our images show structures and give dimensions that correlate well with previous structural studies using transmission electron microscopy.

  • 2.
    Almqvist, Nils
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rubel, Marek
    Royal Institute of Technology, Physics Department, S-10405 Stockholm, Sweden.
    Emmoth, Birger
    Royal Institute of Technology, Physics Department, S-10405 Stockholm, Sweden.
    SFM and STM topographic studies of carbon-based surfaces exposed to deuterium plasma1994In: Book of abstracts: Microprobe Symposium, Vadstena, April 25-26, 1994, 1994Conference paper (Refereed)
  • 3.
    Almqvist, Nils
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rubel, M.
    Physics Department - Frescati, Royal Institute of Technology, Association EURATOM-NFR.
    Fredriksson, Sverker
    Emmoth, B.
    Physics Department - Frescati, Royal Institute of Technology, Association EURATOM-NFR.
    Wienhold, P.
    Institute of Plasma Physics, Forschungszentrum Jülich, Association EURATOM-KFA.
    Ilyinsky, L.
    Institute of Electrical Engineering, St. Petersburg.
    AFM and STM characterization of surfaces exposed to high flux deuterium plasma1995In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 220-222, no 1-3, 917-921 p.Article in journal (Refereed)
    Abstract [en]

    This paper reports the results of scanning tunneling (STM) and atomic force microscopy (AFM) studies of D+ irradiated graphite and graphite-silicon mixtures. The microscopes were used for studying surface topography and for measuring the surface roughness. The substrates were exposed at various temperatures (60 and 700°C) to different doses of deuterium ions in simulators of plasma - surface interactions and in the TEXTOR tokamak. Also nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy were applied for the qualitative and quantitative determination of surface composition. The initial stages of radiation damage, nanometer-sized bubbles/blisters, were found in plasma-eroded surfaces. These structures only appeared in the graphite phase on the multicomponent material. The microroughness of the surfaces was measured. We also used the AFM for probing the thickness of the plasma-modified layers. The results correlate with the presence of deuterium measured by NRA depth-profiling. Moreover, the AFM reveals the co-deposited layers formed on surfaces facing the tokamak plasma. The appearance of these layers is clearly correlated to the amount of co-deposited atoms.

  • 4.
    Almqvist, Nils
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rubel, M.
    Nannetti, C.A.
    Franconi, E.
    Fredriksson, Sverker
    Emmoth, B.
    Scanning probe microscopy and thermo-mechanical characterization of silicon carbide composites1995In: Fourth Euro-Ceramics: the proceedings of the Fourth European Ceramic Society Conference / [ed] S. Meriani; V. Sergo, Gruppo Ed. Faenza Ed. , 1995, Vol. 3, 361-368 p.Conference paper (Refereed)
    Abstract [en]

    series of SiC-based composites was obtained by sintering. Since such materials are considered for fusion applications, their thermal shock resistance and behaviour under deuterium irradiation are of primary interest. Extensive bulk and surface characterisation of pure and doped (AlN, TiB2, graphite) silicon carbides treated by a deuterium plasma was carried out. The change in surface structure following irradiation is addressed, and major factors influencing deuterium retention are discussed.

  • 5.
    Almqvist, Nils
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Rubel, M.
    Royal Institute of Technology, Physics Department-Frescati, Association EURATOM-NFR.
    Wienhold, P.
    Institute of Plasma Physics, Forschungszentrum Jülich, Association EURATOM-KFA.
    Fredriksson, Sverker
    Roughness determination of plasma-modified surface layers with atomic force microscopy1995In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 270, no 1-2, 426-430 p.Article in journal (Refereed)
    Abstract [en]

    Graphite surfaces exposed to the deuterium plasma in the TEXTOR tokamak were characterized in detail by means of scanning probe microscopy, ion beam analysis and colorimetry methods. The aim is to study the composition and structure of thin layer deposits formed on surfaces subjected to the tokamak plasma. The surface roughness was measured and parametrized in terms of fractal dimension and scaling constant. Several different methods for the fractal analysis of plasma-exposed surfaces have been critically evaluated. The main emphasis of this paper is on the correlation between surface roughness (fractal parameters), the amount of deposited atoms and the layer thickness.

  • 6. Anoushirvani, B.
    et al.
    Enström, Daniel
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Ökvist, P.
    Nicolaidis, A.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Gamma-ray bursts from primordial quark objects in space1997In: Proceedings of the Joint Meeting of the Networks 'The Fundamental Structure of Matter' and 'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 1997, 1997Conference paper (Refereed)
    Abstract [en]

    We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.

  • 7.
    Anselmino, Mauro
    et al.
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Predazzi, Enrico
    Dipartimento di Fisica Teorica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Lichtenberg, D.B.
    Department of Physics, Indiana University.
    Diquarks1993In: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 65, no 4, 1199-1233 p.Article in journal (Refereed)
    Abstract [en]

    It is becoming increasingly clear that the concept of a diquark (a two-quark system) is important for understanding hadron structure and high-energy particle reactions. According to our present knowledge of quantum chromodynamics (QCD), diquark correlations arise in part from spin-dependent interactions between two quarks, from quark radial or orbital excitations, and from quark mass differences. Diquark substructures affect the static properties of baryons and the mechanisms of baryon decay. Diquarks also play a role in hadron production in hadron-initiated reactions, deep-inelastic lepton scattering by hadrons, and in e+e- reactions. Diquarks are important in the formation and properties of baryonium and mesonlike semistable states. Many spin effects observed in high-energy exclusive reactions pose severe problems for the pure quark picture of baryons and might be explained by the introduction of diquarks as hadronic constituents. There is considerable controversy, not about the existence of diquarks in hadrons, but about their properties and their effects. In this work a broad selection of the main ideas about diquarks is reviewed.

  • 8. Bergström, Lars
    et al.
    Fredriksson, Sverker
    Backward production on nuclei and the tube model1980In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 21, no 1, 305-307 p.Article in journal (Refereed)
    Abstract [en]

    It is shown that the recent data from Burke et al. on backward production in 200-GeV/c nA collisions are in good agreement with expectations from the collective tube model with tube fragmentation taken into account.

  • 9. Bergström, Lars
    et al.
    Fredriksson, Sverker
    Estimates of recoil nucleon spectra in high-energy hadron-nucleus collisions1977In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 68, no 2, 177-179 p.Article in journal (Refereed)
    Abstract [en]

    It is shown that recent data on the recoil nucleon spectrum in 10.5 GeV/c pion-neon collisions are in excellent agreement with a parameter free estimate from the so called tube model for high-energy hadron-nucleus collisions. A simple independent collision model is also treated.

  • 10. Bergström, Lars
    et al.
    Fredriksson, Sverker
    Is the recently published counterproof of the tube model credible?1978In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 78, no 2-3, 337-341 p.Article in journal (Refereed)
    Abstract [en]

    It is shown that recent data from pion and proton collision with emulsion nuclei at 200 GeV/c are in perfect agreement with expectations from the collective tube model. The opposite conclusion in publications by Azimov et al. came about because the authors ignored the important effects of target fragmentation.

  • 11. Bergström, Lars
    et al.
    Fredriksson, Sverker
    The deuteron in high-energy physics1980In: Reviews of Modern Physics, ISSN 0034-6861, E-ISSN 1539-0756, Vol. 51, no 4, 675-697 p.Article in journal (Refereed)
    Abstract [en]

    The deuterium nucleus plays an important role in several branches of high-energy physics. We review its present status as a neutron source, a relativistic bound state, a collective six-quark state and a double scatterer.

  • 12.
    Blaschke, D.
    et al.
    Gesellschaft für Schwerionenforschung mbH (GSI).
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Grigorian, H.
    Institut für Physik, Universität Rostock.
    Öztas, A.M.
    Department of Physics, Hacettepe University.
    Sandin, Fredrik
    The Phase diagram of three-flavor quark matter under compact star constraints2005In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 72, no 6Article in journal (Refereed)
    Abstract [en]

    The phase diagram of three-flavor quark matter under compact star constraints is investigated within a Nambu-Jona-Lasinio model. Global color and electric charge neutrality is imposed for beta-equilibrated superconducting quark matter. The constituent quark masses and the diquark condensates are determined self-consistently in the plane of temperature and quark chemical potential. Both strong and intermediate diquark coupling strengths are considered. We show that in both cases, gapless superconducting phases do not occur at temperatures relevant for compact star evolution, i.e., below T~50 MeV. The stability and structure of isothermal quark star configurations are evaluated. For intermediate coupling, quark stars are composed of a mixed phase of normal (NQ) and two-flavor superconducting (2SC) quark matter up to a maximum mass of 1.21 M[sun]. At higher central densities, a phase transition to the three-flavor color flavor locked (CFL) phase occurs and the configurations become unstable. For the strong diquark coupling we find stable stars in the 2SC phase, with masses up to 1.33 M[sun]. A second family of more compact configurations (twins) with a CFL quark matter core and a 2SC shell is also found to be stable. The twins have masses in the range 1.30...1.33 M[sun]. We consider also hot isothermal configurations at temperature T=40 MeV. When the hot maximum mass configuration cools down, due to emission of photons and neutrinos, a mass defect of 0.1 M[sun] occurs and two final state configurations are possible

  • 13.
    Blaschke, David
    et al.
    Rostock University.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Grigorian, H.
    Rostock University.
    Oztas, A.M.
    Hacettepe University, Ankara.
    Diquark condensation effects on hot quark star configurations2004In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 736, no 1-2, 203-219 p.Article in journal (Refereed)
    Abstract [en]

    The equation of state for quark matter is derived for a nonlocal, chiral quark model within the mean field approximation. We investigate the effects of a variation of the formfactors of the interaction on the phase diagram of quark matter. Special emphasis is on the occurrence of a diquark condensate which signals a phase transition to color superconductivity and its effects on the equation of state under the condition of β-equilibrium and charge neutrality. We calculate the quark star configurations by solving the Tolman-Oppenheimer-Volkoff equations and obtain for the transition from a hot, normal quark matter core of a protoneutron star to a cool diquark condensed one a release of binding energy of the order of ΔMc2˜1053 erg. We find that this energy could not serve as an engine for explosive phenomena since the phase transition is not first order. Contrary to naive expectations the mass defect increases when for a given temperature we neglect the possibility of diquark condensation.

  • 14.
    Blaschke, David
    et al.
    Rostock University.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Oztas, Ahmet Mecit
    Hacettepe University, Ankara.
    Diquark properties and the TOV equations2001In: Proceedings of the Conference on Compact Stars in the QCD Phase Diagram (CSQCD), Copenhagen, Denmark, August 15 - 18, 2001 / [ed] Rachid Ouyed ..., 2001, 167-173 p.Conference paper (Refereed)
    Abstract [en]

    We present various results from including diquark properties and the gap equations into the TOV equations for compact quark objects. One such property is the diquark form factor, which has a strong influence on various quantities. We discuss the consequences for quark stars.

  • 15. Carlsson, Ella
    et al.
    Fedorov, A.
    Budnik, E.
    Barabash, Stas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    First results from ASPERA-3 Ion Mass Analyzer (IMA) on CO2+ escape2005Conference paper (Other academic)
  • 16.
    Dugne, Jean-Jacques
    et al.
    Laboratoire de Physique Corpusculaire, Université Blaise Pascal Clermont-Ferrand.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Preon trinity: a schematic model of leptons, quarks and heavy vector bosons2002In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 60, no 2, 188-194 p.Article in journal (Refereed)
    Abstract [en]

    Quarks, leptons and heavy vector bosons are suggested to be composed of stable spin- (1/2) preons, existing in three flavours, combined according to simple rules. Straightforward consequences of an SU(3) preon-flavour symmetry are the conservation of three lepton numbers, oscillations and decays between some neutrinos, and the mixing of the d and s quarks, as well as of the vector fields W0 and B0. We find a relation between the Cabibbo and Weinberg mixing angles, and predict new (heavy) leptons, quarks and vector bosons, some of which might be observable at the Fermilab Tevatron and the future CERN LHC. A heavy neutrino might even be visible in existing data from the CERN LEP facility.

  • 17. Dugne, Jean-Jacques
    et al.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Predazzi, Enrico
    Higgs pain? Take a preon!1997In: Proceedings of the Meeting on 'The Fundamental Structure of Matter' and 'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 1997, 1997Conference paper (Refereed)
    Abstract [en]

    The Higgs mechanism is the favourite cure for the main problem with electroweak unification, namely how to reconcile a gauge theory with the need for massive gauge bosons. This problem does not exist in preon models for quark and lepton substructure with composite $Z^0$ and $W$s, which, consequently, also avoid all other theoretical complications and paradoxes with the Higgs mechanism. We present a new, minimal preon model, which explains the family structure, and predicts several new, heavy quarks, leptons and vector bosons. Our preons obey a phenomenological supersymmetry, but without so-called squarks and sleptons, since this SUSY is effective only on the composite scale.

  • 18. Dugne, Jean-Jacques
    et al.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Predazzi, Enrico
    Preon Trinity: a new model of leptons and quarks1999In: Beyond the desert 1999: accelerator, non-accelerator, and space approaches into the next millennium ; proceedings of the Second International Conference on Particle Physics Beyond the Standard Model, Castle Ringberg, Germany, 6 - 12 June 1999 / [ed] Hans Volker Klapdor-Kleingrothaus, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 1999Conference paper (Refereed)
    Abstract [en]

    A new model for the substructure of quarks, leptons and weak gauge bosons, is discussed. It is based on three fundamental and absolutely stable spin-1/2 preons. Its preon flavour SU(3) symmetry leads to a prediction of nine quarks, nine leptons and nine heavy vector bosons. One of the quarks has charge $-4e/3$, and is speculated to be the top quark (whose charge has not been measured). The flavour symmetry leads to three conserved lepton numbers in all known weak processes, except for some neutrinos, which might either oscillate or decay. There is also a (Cabibbo) mixing of the $d$ and $s$ quarks due to an internal preon-antipreon annihilation channel. An identical channel exists inside the composite $Z^0$, leading to a relation between the Cabibbo and Weinberg mixing angles.

  • 19. Dugne, Jena-Jacques
    et al.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Predazzi, Enrico
    Preon trinity1998Report (Other academic)
    Abstract [en]

    We present a new minimal model for the substructure of all known quarks, leptons and weak gauge bosons, based on only three fundamental and stable spin-1/2 preons. As a consequence, we predict three new quarks, three new leptons, and six new vector bosons. One of the new quarks has charge $-4e/3$. The model explains the apparent conservation of three lepton numbers, as well as the so-called Cabibbo-mixing of the $d$ and $s$ quarks, and predicts electromagnetic decays or oscillations between the neutrinos $\bar{\nu}_{\mu}$ ($\nu_{\mu}$) and $\nu_e$ ($\bar{\nu}_e$). Other neutrino oscillations, as well as rarer quark mixings and CP violation can come about due to a small quantum-mechanical mixing of two of the preons in the quark and lepton wave functions.

  • 20. Eilam, G.
    et al.
    Fredriksson, Sverker
    Small angle production from nuclear and nucleon targets1980In: Lettere al Nuovo Cimento della Società Italiana di Fisica, ISSN 0375-930X, Vol. 27, 299- p.Article in journal (Refereed)
  • 21. Ekelin, Svante
    et al.
    Fredriksson, Sverker
    Hadron pT correlations in quark jets1986In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 56, no 22, 2428-2428 p.Article in journal (Refereed)
  • 22. Ekelin, Svante
    et al.
    Fredriksson, Sverker
    Large-pT protons from constituent diquark scattering1984In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 149, no 6, 509-513 p.Article in journal (Refereed)
    Abstract [en]

    Recent data from the CERN ISR on the fractional proton yield in pp collisions are explained within the Stockholm diquark model. Describing the proton as a u(ud)0 system, the observed high magnitude and fall-off pT, θ and √s of the proton yield are natural consequences of constituent diquark elastic scattering. The pT and θ dependence favour a value of around 10 GeV2/c2 for the size parameter in the diquark form factor, corresponding to a diquark rms radius of around 0.2 fm. This is consistent with earlier results of the model applied to deep inelastic lepton-nucleon scattering and e+e- annihilation

  • 23. Ekelin, Svante
    et al.
    Fredriksson, Sverker
    Jändel, Magnus
    Larsson, Tomas
    Baryons from diquarks in e+e- annihilation1983In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 28, no 1, 257-259 p.Article in journal (Other academic)
    Abstract [en]

    We find experimental support for the view that diquarks appear only as spin-0 objects. When their production rate in the color field of a quark from e+e- annihilation is described by the appropriate Schwinger formula for scalars, it turns out that they must be substantially lighter than earlier believed in order to explain the baryon yield.

  • 24. Ekelin, Svante
    et al.
    Fredriksson, Sverker
    Jändel, Magnus
    Larsson, Tomas
    Indications of hard diquarks in e+e- annihilation1984In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 30, no 11, 2310-2315 p.Article in journal (Refereed)
    Abstract [en]

    It is suggested that very small spin-0 diquarks are directly produced in e+e- annihilation and then fragment into leading baryons and other hadrons. The most influential diquark is the charmed diquark (uc), due to its high charge. It gives a sizable contribution to the hadronic R factor and to the two-jet angular distribution in the energy region W=4-8 GeV. At these energies, a careful study of Λ production would provide the best additional test of the model.

  • 25.
    Elfgren, Erik
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Mass limits for heavy neutrinos2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 479, no 2, 347-353 p.Article in journal (Refereed)
    Abstract [en]

    Context. Neutrinos heavier than MZ/2 ∼ 45 GeV are not excluded by particle physics data. Stable neutrinos heavier than this might contribute to the cosmic gamma ray background through annihilation in distant galaxies, as well as to the dark matter content of the universe.Aims. We calculate the evolution of the heavy neutrino density in the universe as a function of its mass, MN, and then the subsequent gamma ray spectrum from annihilation of distant N ¯N (from 0 < z < 5).Methods. The evolution of the heavy neutrino density in the universe is calculated numerically. To obtain the enhancement due to structure formation in the universe, we approximate the distribution of N to be proportional to that of dark matter in the GalICS model. The calculated gamma ray spectrum is compared to the measured EGRET data.Results. A conservative exclusion region for the heavy neutrino mass is 100 to 200 GeV, both fromEGRET data and our re-evalutation of the Kamiokande data. The heavy neutrino contribution to dark matter is found to be at most 15%.

  • 26. Enström, Daniel
    et al.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Luminosities of high-redshift objects in an accelerating universe1999Report (Other academic)
    Abstract [en]

    The results from the Supernova Cosmology Project indicate a relation between cosmic distance and redshift that corresponds to an accelerating Universe, and, as a consequence, the presence of an energy component with negative pressure. This necessitates a re-evaluation of such astrophysical luminosities that have been derived through conventional redshift analyses of, e.g., gamma-ray bursts and quasars. We have calculated corrected luminosity distances within two scenarios; the standard one with a non-zero cosmological constant, and the more recently proposed ``quintessence'', with a slowly evolving energy-density component. We find luminosity corrections from +30 to -40 per cent for redshifts with $z=0 - 10$. This finding implicates that the SCP data do not, by themselves, require a revision of the current, rather qualitative modeling of gamma-ray bursts and quasar properties.

  • 27. Enström, Daniel
    et al.
    Fredriksson, Sverker
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nicolaidis, A.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    A Quark matter dominated universe1998Report (Other academic)
    Abstract [en]

    We present a new scenario for the development of the Universe after the Big Bang, built on the conjecture that a vast majority of the primordial quark matter did not undergo a phase transition to normal nuclear matter, but rather split up into massive quark objects that remained stable. Hence, such primordial quark matter would make up the so-called dark matter. We discuss, mostly in qualitative terms, the consequences for galaxy formation, the origin of normal matter, the occurrence of massive black-holes in galactic centres and the cosmic gamma-ray bursts.

  • 28. Enström, Daniel
    et al.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Hansson, Johan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Nicolaidis, A.
    Ekelin, Svante
    Kungliga tekniska högskolan, KTH.
    Gamma-Ray Bursts and Dark Matter: a joint origin?1998Conference paper (Refereed)
  • 29. Fredriksson, Sverker
    A phenomenological two-component picture of large transverse momentum production1976In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 63, no 3, 321-323 p.Article in journal (Refereed)
    Abstract [en]

    It is suggested that large-pT hadrons can be classified into two categories with completely different properties according to whether they contain a leading quark or just sea quarks from the initial projectile-target system. From simple quark counting we get relations between hadron ratios at large pT, which are consistent with data.

  • 30.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    A (ud)-cious model of the proton1994In: Workshop on diquarks II: Villa Gualino, Torino, Italy, 2 - 4 November 1992 / [ed] Mauro Anselmino, Singapore: World Scientific and Engineering Academy and Society, 1994, 14-23 p.Conference paper (Refereed)
  • 31. Fredriksson, Sverker
    An estimate of the effect of nuclear Fermi motion on large transverse momentum inclusive spectra from high-energy proton-nucleus collisions1975In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 94, no 2, 337-343 p.Article in journal (Refereed)
    Abstract [en]

    The effect of nuclear Fermi motion on large-pT inclusive hadron spectra and particle ratios from high-energy proton-nucleus collisions is estimated within the scope of the parton model for proton-nucleon collisions and the box model for the nucleus. Considerable effects are found in some cases.

  • 32. Fredriksson, Sverker
    Clusters and tubes in multiparticle production from nuclear targets1980In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 45, no 17, 1371-1374 p.Article in journal (Refereed)
    Abstract [en]

    Recent data on backward pion production in 0.8-4.89-GeV proton-nucleus collisions are analyzed within the scope of models where target nucleons react collectively. It is shown that the nuclear-size dependence in data is a sensitive probe of the effective target mass. The experimental results hint at a synthesis of the cluster ("fluctuon") model and the collective tube model.

  • 33.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Cosmic diquarks1998In: Workshop on Diquarks III: Villa Gualino, Torino, Italy, 28 -30 October 1996 / [ed] Mauro Anselino, Singapore: World Scientific Publishing Co Pte Ltd , 1998, 99-108 p.Conference paper (Refereed)
  • 34. Fredriksson, Sverker
    Demons at Celcius?1983In: Uppsala Workshop, Kungl. Tekniska Högskolan , 1983Conference paper (Refereed)
  • 35. Fredriksson, Sverker
    Diquarks1987In: Proceedings: Dubna HEP Seminar 1986, Joint Institute for Nuclear Research , 1987, Vol. v.2:134Conference paper (Refereed)
  • 36. Fredriksson, Sverker
    Diquarks1983In: Proceedings / [ed] Z. Ajduk, Warsaw Univ., Inst. Theor. Phys. , 1983Conference paper (Refereed)
  • 37. Fredriksson, Sverker
    Electron-positron annihilation and related topics: an elementary introduction1975Report (Other academic)
  • 38. Fredriksson, Sverker
    Hello diquark, goodbye gluon !1984In: New Particle Production: Proceedings of the Hadronic session of the Nineteenth Rencontres de Moriond / [ed] J. Tran Thanh Van, Editions Frontieres , 1984, Vol. 2, 479- p.Conference paper (Refereed)
  • 39. Fredriksson, Sverker
    Large-pT π0 Production in High-Energy πp Collisions1976In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 37, no 21, 1373-1374 p.Article in journal (Refereed)
    Abstract [en]

    It is pointed out that the recently measured difference in pT spectrum between π±p→π0X and pp→π0X, with a large-pT π0, seems to be a consequence only of the smaller number of quarks per projectile in a pion beam.

  • 40. Fredriksson, Sverker
    Nuclear structure functions and the size of diquarks in nucleons1984In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 52, no 9, 724-726 p.Article in journal (Refereed)
    Abstract [en]

    It is suggested that the observed difference between deep-inelastic structure functions from iron and deuterium targets comes about because two of the quarks in a nucleon are tightly bound in a diquark. It suffices for reproducing the data to assume that the diquark radius is enhanced by 10%-45% in a dense nucleus because of the disturbance from the surrounding nucleons. It is suggested how such a change of the diquark scale could be distinguished from the recently proposed change in the scale of the whole nucleon.

  • 41. Fredriksson, Sverker
    On large transverse momentum production in high-energy proton-nucleus collisions1976In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 111, no 1, 167-177 p.Article in journal (Refereed)
    Abstract [en]

    Experimental data from inclusive production of large pT hadronsin high-energy proton-nucleus collisions are analysed with emphasis on the influence of the size of the target nucleus. It is found that data at pT≤3 GeV/c are consistent with the hypothesis that the incoming proton collides "simultaneously" with all the nucleons in its way, resulting in an effective collision energy larger than the one expected in a single proton-nucleon hit. At pT > 3 GeV/c, data are in conflict with such a simple model, a result we think is a consequence of the dominance of hard parton collisions at very large pT.

  • 42. Fredriksson, Sverker
    On the production of hadrons with large transverse momenta in high-energy proton-proton and proton-nucleus collisions1976Doctoral thesis, comprehensive summary (Other academic)
  • 43. Fredriksson, Sverker
    Particle ratios in the central region of high-energy proton-proton collisions1975In: Nuclear Physics B, ISSN 0550-3213, E-ISSN 1873-1562, Vol. 84, no 1, 234-252 p.Article in journal (Refereed)
    Abstract [en]

    Recent data from NAL on particle ratios ... large transverse momentum are analysed with emphasis on the surprising discovery that pions increase their dominance over heavier hadrons at increasing transverse momentum. It is argued that this is not a phase space or threshold effect but a dynamical feature that can be used to test theoretical models of multiparticle production. Most models of interest, such as for instance the parton, the hydrodynamical and the two-component model, may however be extended, in a simple-minded way, to kaon and antiproton production as to predict ratios of heavier to lighter hadrons to fall with increasing large transverse momentum.

  • 44. Fredriksson, Sverker
    Phenomenological relations between large-pT meson spectra1978In: Physical Review D. Particles and fields, ISSN 0556-2821, E-ISSN 1089-4918, Vol. 18, no 11, 4144-4151 p.Article in journal (Refereed)
    Abstract [en]

    Recent data on the hadron ratios π+π-, K+π+, K-π-, and ηπ0 at large transverse momenta are shown to be consistent with predictions from a simple phenomenological two-component picture for large-pT production. The very-large-pT part of meson spectra is assumed to be dominated by particles that contain one of the incoming valence quarks, while small-and medium-pT mesons are built up mostly of quarks created in quark-antiquark pairs. Exceptions are K- and φ spectra, where for obvious reasons the very-large-pT component is missing. Simple relations between π, K, and η spectra are found. Predictions for the large-pT spectrum of φ mesons are presented.

  • 45.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Preon prophecies by the standard model2003In: Beyond the desert 2003: proceedings of the Fourth Tegernsee International Conference on Particle Physics Beyond the Standard Model, Beyond 2003, Castle Ringberg, Tegernsee, Germany, 9 - 14 June 2003 / [ed] Hans Volker Klapdor-Kleingrothaus, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2003, 211-223 p.Conference paper (Refereed)
    Abstract [en]

    The Standard Model of quarks and leptons is, at first sight, nothing but a set of ad hoc rules, with no connections, and no clues to their true background. At a closer look, however, there are many inherent prophecies that point in the same direction: Compositeness in terms of three stable preons.

  • 46. Fredriksson, Sverker
    Recent results from the tube model for high-energy collisions with nuclei1978In: Proceedings of the topical meeting on recent developments in high-energy physics, Campione d'Italia, 3-7 October 1977 / [ed] Gianpaolo Bellini, Bologna: Compositor , 1978Conference paper (Refereed)
  • 47. Fredriksson, Sverker
    The collective tube model and how to disprove it1979In: First workshop on ultra-relativistic nuclear collisions: [LBL, May 21-24, 1979], Berkeley, Calif: Lawrence Berkeley National Laboratory , 1979Conference paper (Refereed)
  • 48. Fredriksson, Sverker
    The Emc effect as a diquark phenomenon1983Report (Other academic)
  • 49.
    Fredriksson, Sverker
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    The Stockholm diquark model1989In: Workshop on diquarks / [ed] Mauro Anselmino; Enrico Predazzi, Singapore: World Scientific and Engineering Academy and Society, 1989, 22-57 p.Conference paper (Refereed)
  • 50. Fredriksson, Sverker
    Vad har kvarkarna för sig i atomkärnan?1985Other (Other (popular science, discussion, etc.))
12 1 - 50 of 73
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