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Ex-rayon carbon yarns have been prepared according to an original route characterized by a fast pyrolysis step in the presence of an organosilicon compound. The evolution of the mechanical and physicochemical properties of the fibres throughout the transformation of cellulose into carbon showed that the organosilicon additive was necessary to obtain carbon yarns exhibiting satisfactory mechanical behaviour and to improve significantly the fracture properties of the ex-rayon carbon fibres.

The NA60 experiment at the CERN SPS has studied low-mass muon pairs in 158 A GeV In–In collisions. A strong excess of pairs is observed above the yield expected from neutral meson decays. The unprecedented sample size close to 400000 events and the good mass resolution of about 2% made it possible to isolate the excess by subtraction of the decay sources. The shape of the resulting mass spectrum shows some non-trivial centrality dependence, but is largely consistent with a dominant contribution from π+π-→ϱ→μ+μ- annihilation. The associated ϱ spectral function exhibits considerable broadening, but essentially no shift in mass. The pT-differential mass spectra show the excess to be much stronger at low pT than at high pT. The results are compared to theoretical model predictions; they tend to rule out models linking hadron masses directly to the chiral condensate.

The NA60 experiment at the CERN SPS has measured muon pairs with unprecedented precision in 158  A  GeV In–In collisions. A strong excess of pairs above the known sources is observed in the whole mass region 0.2< M <2.6 GeV. The mass spectrum for M <1 GeV is consistent with a dominant contribution from π + π − → ρ → μ + μ − annihilation. The associated ρ spectral function shows a strong broadening, but essentially no shift in mass. For M >1 GeV, the excess is found to be prompt, not due to enhanced charm production, with pronounced differences to Drell–Yan pairs. The slope parameter T eff associated with the transverse momentum spectra rises with mass up to the ρ , followed by a sudden decline above. The rise for M <1 GeV is consistent with radial flow of a hadronic emission source. The seeming absence of significant flow for M >1 GeV and its relation to parton–hadron duality is discussed in detail, suggesting a dominantly partonic emission source in this region. A comparison of the data to the present status of theoretical modeling is also contained. The accumulated empirical evidence, including also a Planck-like shape of the mass spectra at low p T and the lack of polarization, is consistent with a global interpretation of the excess dimuons as thermal radiation. We conclude with first results on ω in-medium effects.

A model SiC-fibre has been prepared from a polycarbosilane precursor by means of an irradiation oxygen-free curing process. The chemical composition remains unchanged after heat treatments under an inert atmosphere for pyrolysis temperatures of 1600°C. At this temperature, the fibre consists of SiC nanocrystals (mean size 6–10 nm) and free carbon. However, a slow grain growth takes place as the temperature is increased. The fibre retains a high strength at room and high temperatures up to temperatures of 1600 °C when the pyrolysis has been performed under nitrogen. The electrical conductivity was studied as a function of the pyrolysis temperature Tp: For 1100≤Tp≤1200 °C, the conductivity increases by several orders of magnitude due to the reorganization of the free carbon phase at the SiC grain boundaries. Oxidation kinetics of the filaments remain parabolic from 1000–1400 °C.

The NA60 experiment has studied low-mass muon pair production in proton–nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the \\[\\rho /\\omega \\] and \\[\\phi \\] mesons are measured in the full \\[p_{\\mathrm {T}}\\] range accessible, from \\[p_{\\mathrm {T}}= 0\\] up to \\[2 \\, {\\hbox {GeV/c}}\\]. The nuclear dependence of the production cross sections of the \\[\\eta \\], \\[\\omega \\] and \\[\\phi \\] mesons has been found to be consistent with the power law \\[\\sigma _{\\mathrm {pA}} \\propto {\\mathrm {A}}^\\alpha \\], with the \\[\\alpha \\] parameter increasing as a function of \\[p_{\\mathrm {T}}\\] for all the particles, and an approximate hierarchy \\[\\alpha _\\eta \\approx \\alpha _\\phi > \\alpha _\\omega \\]. The cross section ratios \\[\\sigma _\\eta /\\sigma _\\omega \\], \\[\\sigma _\\rho /\\sigma _\\omega \\] and \\[\\sigma _\\phi /\\sigma _\\omega \\] have been studied as a function of the size A of the production target, and an increase of the \\[\\eta \\] and \\[\\phi \\] yields relative to the \\[\\omega \\] is observed from p–Be to p–U collisions.

NA60 is a fixed-target experiment at the CERN SPS which measured dimuon production in nucleus–nucleus and proton–nucleus collisions. The experiment collected muon pair samples of unprecedented quality in heavy-ion experiments. This paper presents a high quality measurement of the pT distribution of the φ meson, covering a broad pT window. The data were collected in 2003 in In-In collisions at 158 GeV per nucleon. The results, presented as a function of centrality, were studied against several possible sources of systematic effects and proved to be fairly stable. We show that the inverse mT slope measured in In-In collisions, in the φ→μμ decay channel, depends significantly on the range used to perform the fit. When the fit is performed at low transverse momentum, the effective inverse slope increases from peripheral to central collisions, as measured by other experiments. We finally show that our measurement for In-In is compatible with the overall systematics of T slope versus mass, measured in different collision systems by the NA49 experiment

Strigolactone (SL) mutants in diverse species show reduced stature in addition to their extensive branching. Here, we show that this dwarfism in pea (Pisum sativum) is not attributable to the strong branching of the mutants. The continuous supply of the synthetic SL GR24 via the root system using hydroponics can restore internode length of the SL-deficient rms1 mutant but not of the SL-response rms4 mutant, indicating that SLs stimulate internode elongation via RMS4. Cytological analysis of internode epidermal cells indicates that SLs control cell number but not cell length, suggesting that SL may affect stem elongation by stimulating cell division. Consequently, SLs can repress (in axillary buds) or promote (in the stem) cell division in a tissue-dependent manner. Because gibberellins (GAs) increase internode length by affecting both cell division and cell length, we tested if SLs stimulate internode elongation by affecting GA metabolism or signaling. Genetic analyses using SL-deficient and GA-deficient or DELLA-deficient double mutants, together with molecular and physiological approaches, suggest that SLs act independently from GAs to stimulate internode elongation.

The NA60 experiment studies open charm and prompt dimuon production in proton-nucleus and nucleus-nucleus collisions at the CERN SPS. From June 2002 to November 2004 we collected data on dimuon production from proton-nucleus and Indium-Indium collisions. These data samples allow us to study low mass dimuon production (resonances and continuum), J/π suppression and open-charm production. We will also search for thermal dileptons, through the yield of \"intermediate mass dimuons\". In this paper we briefly overview some of the results obtained up to now, after shortly describing the detector.

A quasi-stoichiometric SiC-based fibre, has been prepared at a pyrolysis temperature of 1800°C, from a boron-doped polycarbosilane precursor using an extrusion-chemical curing-pyrolysis procedure. The green fibre was rendered infusible by sequential curing with ozone and trimethylamine-borane adduct (O3/Me3N : BH3). The fibre was characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, electron energy loss spectroscopy and Raman spectroscopy.

Two methods for preparing precursors of Si/C/B-based thermostructural materials have been developed. The first consists of a thermal treatment of a mixture of polydimethylsilane (PDMS), (Me2Si)n, and triethylamine–borane adduct, Et3N : BH3 at atmospheric pressure. The second involves two steps: (i) transformation of PDMS into a polymer displaying Si–CH2–Si and Si–Si linkages in its backbone, and (ii) heating this product at atmospheric pressure, in the presence of Et3N: BH3. The ceramic material obtained from the second approach contains 2.2 at% boron and 1.5 at% oxygen.