| 1. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Acharya, B. S., et al.
(författare)
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Introducing the CTA concept
- 2013
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
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| 3. |
- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 4. |
- Abramowicz, H., et al.
(författare)
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Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA
- 2013
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:2
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma(c (c) over bar)(red) for charm production are obtained in the kinematic range of photon virtuality 2.5 <= Q(2) <= 2000 GeV2 and Bjorken scaling variable 3 . 10(-5) <= x <= 5 . 10(-2). The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W-+/- and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.
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| 5. |
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| 6. |
- Alexa, C., et al.
(författare)
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Elastic and proton-dissociative photoproduction of J/psi mesons at HERA
- 2013
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:6
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Tidskriftsartikel (refereegranskat)abstract
- Cross sections for elastic and proton-dissociative photoproduction of J/psi mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies root s approximate to 318 GeV and root s approximate to 225 GeV, corresponding to integrated luminosities of L = 130 pb(-1) and L = 10.8 pb(-1), respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25 < W-gamma p < 110 GeV. Differential cross sections d sigma/dt, where t is the squared four-momentum transfer at the proton vertex, are measured in the range vertical bar t vertical bar < 1.2 GeV2 for the elastic process and vertical bar t vertical bar < 8 GeV2 for proton dissociation. The results are compared to other measurements. The W-gamma p and t-dependences are parametrised using phenomenological fits.
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| 7. |
- Alexa, C., et al.
(författare)
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Measurement of charged particle spectra in deep-inelastic ep scattering at HERA
- 2013
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:4
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Tidskriftsartikel (refereegranskat)abstract
- Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5 < Q(2) < 100 GeV2, and small values of Bjorken-x, 10(-4) < x < 10(-2). The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (n(*)) and transverse momentum (p(T)(*)) in the range 0 < n(*) < 5 and 0 < p(T)(*) < 10 GeV in bins of x and Q(2). The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.
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| 8. |
- Johansen, J. G., et al.
(författare)
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Experimental study of bound states in Be-12 through low-energy Be-11(d,p)-transfer reactions
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 88:4
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Tidskriftsartikel (refereegranskat)abstract
- The bound states of Be-12 have been studied through a Be-11(d, p) Be-12 transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of Be-11 was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in Be-12. The gamma-ray detection enabled a clear identification of the four known bound states in Be-12, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from distorted wave Born approximation (DWBA) calculations and have been compared to previous experimental and theoretical results.
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| 9. |
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| 10. |
- Werdelin, Lars, et al.
(författare)
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Locating specimens of extinct tiger (Panthera tigris) subspecies: Caspian tiger (P. t. virgata), Javan tiger (P. t. sondaica), and Balinese tiger (P. t. balica) – including previously unpublished specimens
- 2013
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Ingår i: Mammal Study. - : Mammalogical Society of Japan. - 1343-4152 .- 1348-6160. ; 38, s. 187-198
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in multivariate statistics, and in ancient DNA techniques, have greatly increased understanding of tiger phylogeography. However, regardless of advances in analytical methodology, researchers will continue to need access to specimens for morphological measurements and sampling for genetic analysis. The tiger has become increasingly endangered, and out of the nine putative tiger subspecies, three (Javan, Balinese, and Caspian) have become extinct in the last 100 years, leaving the specimens kept in natural history collections as the only materials available for research. Frustratingly little information is widely available concerning the specimens of these extinct tiger subspecies. We conducted an extensive search for specimens of extinct tiger subspecies, and also developed a simple on-site method to assign unprovenanced and probable Indonesian specimens to either Javan/Balinese or Sumatran subspecies. We located a total of 88 Javan, 11 Balinese, and 46 Caspian tigers, including seven new Javan tigers, and three Balinese tigers that were not widely known previously. These specimens are critical for research in order to understand the intraspecific phylogeny and evolutionary history of the tiger.
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