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- Abt, I, et al.
(författare)
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Measurement of the b(b)over-bar production cross section in 920 GeV fixed-target proton-nucleus collisions
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 26:3, s. 345-355
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Tidskriftsartikel (refereegranskat)abstract
- Using the HERA-B detector, the b (b) over bar production cross section has been measured in 920 GeV proton collisions on carbon and titanium targets. The b (b) over bar production was tagged via inclusive bottom quark decays into J/psi by exploiting the longitudinal separation of J/psi --> l(+)l(-) decay vertices from the primary proton-nucleus interaction. Both e(+)e(-) and mu(+)mu(-) channels have been reconstructed and the combined analysis yields the cross section sigma(b (b) over bar) = 32(-12)(+14)(stat) (+6)(-7)(sys) nb/nucleon.
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- Abt, I, et al.
(författare)
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Inclusive V-0 production cross sections from 920 GeV fixed target proton-nucleus collisions
- 2003
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 29:2, s. 181-190
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Tidskriftsartikel (refereegranskat)abstract
- Inclusive differential cross sections dsigma(pA)/dx(F) and dsigma(pA)/dp(t)(2) for the production of K-S(0), Lambda, and (&ULambda;) over bar particles are measured at HERA in proton-induced reactions on C, Al, Ti, and W targets. The incident beam energy is 920 GeV, corresponding to roots = 41.6 GeV in the proton-nucleon system. The ratios of differential cross sections dsigma(pA)(K-S(0))/dsigma(pA)(Lambda) and dsigma(pA)((&ULambda;) over bar)/dsigma(pA) (Lambda) are measured to be 6.2 +/- 0.5 and 0.66 +/- 0.07, respectively, for x(F) approximate to -0.06. No significant dependence upon the target material is observed. Within errors, the slopes of the transverse momentum distributions da,Ald t also show no significant dependence upon the target material. The dependence of the extrapolated total cross sections sigma(pA) on the atomic mass A of the target material is discussed, and the deduced cross sections per nucleon sigma(pN) are compared with results obtained at other energies.
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- Liu, Bingbing, et al.
(författare)
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Synthesis and characterization of single-walled nanotubes produced with Ce as catalyst
- 2000
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Ingår i: Molecular Materials: Molecular Crystals and Liquid Crystals Section C, vol. 13. - : Overseas Publishers Association N.V.. ; , s. 75-80
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Konferensbidrag (refereegranskat)abstract
- We have studied the effect of using rare-earth elements C (typically +4 oxide state) and Eu (typically +2 oxide state) together with nanometer Ni as catalysts to synthesize SWNT in high yield by arc evaporation. A black collar deposit containing mainly SWNT was formed in the presence of Ce/Ni while only nanometer carbon particles were formed using Eu/Ni, as identified by SEM, TEM and Raman spectra. The Raman spectra of our SWNT mats show difference from spectra shown in the literature in a low frequency range, indicating that our mats contain chiral tubes. The temperature dependent resistance of SWNT mats was also measured. A semiconducting behaviour was observed with a negative dR/dT and no resistance minimum from 2 to 350 K. The resistance follows a 2D variable range hopping behaviour.
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