| 1. |
- 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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| 2. |
- 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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| 3. |
- Adler, SS, et al.
(författare)
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Double helicity asymmetry in inclusive midrapidity pi(0) production for polarized p+p collisions at root s=200 GeV
- 2004
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Ingår i: Physical Review Letters. - 1079-7114. ; 93:20: 202002
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at roots=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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| 4. |
- Fischer, S. M., et al.
(författare)
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Alignment delays in the N = Z nuclei Kr-72, Sr-76, and Zr-80
- 2001
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 8713:13
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Tidskriftsartikel (refereegranskat)abstract
- The ground state rotational bands of the N = Z nuclei Kr-72, Sr-76, and Zr-80 have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. Kr-72 shows the most marked effect. It has been widely suggested that these delayed alignments arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.
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| 5. |
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| 6. |
- Bauer, D
(författare)
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Order estimation for subspace methods
- 2001
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Ingår i: Automatica. - 0005-1098 .- 1873-2836. ; 37:10, s. 1561-1573
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the question of estimating the order in the context of subspace methods is addressed. Three different approaches are presented and the asymptotic properties thereof derived. Two of these methods are based on the information contained in the estimated singular values, while the third method is based on the estimated innovation variance. The case with observed inputs is treated as well as the case without exogenous inputs. The two methods based on the singular values are shown to be consistent under fairly mild assumptions, while the same result for the third approach is only obtained on a generic set. The former can be applied to Larimore type of procedures as well as to MOESP type of procedures, whereas the third is only applied to Larimore type of algorithms. This has implications for the estimation of the order of systems, which are close to the exceptional set, as is shown in a numerical example. All the estimation methods involve the choice of a penalty term. Sufficient conditions on the penalty term to guarantee consistency are derived. The effects of different choices of the penalty term are investigated in a simulation study. (C) 2001 Elsevier Science Ltd. All rights reserved.
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| 7. |
- Bauer, S H J, et al.
(författare)
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A rapid and sensitive procedure for determination of 5-N-acetyl neuraminic acid in lipopolysaccharides of Haemophilus influenzae : a survey of 24 non-typeable H-influenzae strains
- 2001
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 335:4, s. 251-260
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Tidskriftsartikel (refereegranskat)abstract
- In view of the importance of 5-N-acetyl neuraminic acid in bacterial pathogenesis, a sensitive, reproducible and reliable method for the determination of 5-N-acetyl neuraminic acid levels in lipopolysaccharide (LPS) is described and applied to 24 different non-typeable Haemophilus influenzae (NTHi) strains. The method involves analysis by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) of terminal 5-N-acetyl neuraminic acid residues released by neuraminidase treatment of O-deacylated LPS. The procedure is relatively fast and the instrumental effort is moderate. The results of the procedure were compared with data obtained by H-1 NMR and electrospray ionisation-mass spectrometry (ESI-MS). The analysis of LPS from 24 NTHi strains showed that 5-N-acetyl neuraminic acid was found to be a common constituent of LPS in NTHi. Only one strain (NTHi 432) did not show any sialylation. Molar ratios (LPS /5-N-acetyl neuraminic acid) ranged between 5/1 and 500/1. Several strains in which no 5-N-acetyl neuraminic acid could be determined by other methods including 1H NMR and ESI-MS were shown to contain 5-N-acetyl neuraminic acid by this HPAEC-PAD procedure. The method was applied to determine levels of terminal 5-N-acetyl neuraminic acid in LPS from NTHi strains grown under different conditions and mutant strains containing inactive LPS biosynthetic genes.
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| 8. |
- Crispin, Annica, et al.
(författare)
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Influence of dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors
- 2002
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 116:18, s. 8159-8167
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors was studied by means of photoelectron spectroscopy. With lithium atoms as dopants, two charges were stored on the same spiro branch in the form of bipolarons, for spiro-quarterphenyl and spiro-sexiphenyl. For doping with the sodium atoms, the size of the counter ions made it less energetically desirable to store two charges onto a single branch, and the charged species were polarons independent of the level of doping which was confirmed by optical absorption data.
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| 9. |
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| 10. |
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