201,656 research outputs found
Study of D* (2010)± production in ep collisions at HERA
No full textWe report the first observation of charmed mesons with the ZEUS detector at HERA using the decay channel D*+- -->(D0 --> K-pi+) pi+ (+ cc.). Clear signals in the mass difference delta M=M(D*)-M(D0) as as well as in the M(Kpi) distribution at the D0 mass are found. The ep cross section for inclusive D*± production with Q^2 < 4 GeV^2 in the γp centre-of-mass energy range 115 < W < 275 GeV has been determined to be (32±7−7+4) nb in the kinematic region pt(D*) ≥ 1.7 GeV, |eta(D*)| < 1.5. Extrapolating outside this region, assuming a mass of the charm quark of 1.5 GeV, we estimate the ep charm cross section. The increase of the total charm photoproduction cross section by one order of magnitude with respect to low energy data experiments is well described by QCD NLO calculations using singular gluon distributions in the proton
Derrick.
No full textPatent for a portable derrick "in which the derrick-frame is rotatable, the same being especially adapted for use in handling bales of cotton, baggage, ice, and other heavy articles." (Lines 14-17) Includes instructions and illustrations
DERRICK CRANE ROBUSTNESS SCENARIOS
No full textThe paper deals with derrick cranes (derricks) that are equipment typically used in the mining industry and focuses on the analysis of few robustness scenarios. Derricks are composed of built-up steel members which are widely and efficiently used in hoisting applications due to their high payloads at relevant outreaches. During the in-service use, local damages might occur and as such, the aim of the paper is to study how such damages influence the overall structural performance. In particular, reference was made to a derrick for which six geometrical configurations and five different damage scenarios have been analysed. Owing it to the extensive use of angles in the built-up compo-nent of each derrick, structural analyses have been carried out by using a commercial refined finite element analysis package (FEAP) offering the warping torsion as an additional degree of freedom for each beam node. Research out-comes allow for a clear identification of the parts of a derrick that should be protected and well-designed to guarantee a robust structure for its entire in-service lif
Observation of events with a large rapidity gap in deep inelastic scattering at HERA
No full textIn deep inelastic, neutral current scattering of electrons and protons at square-root s = 296 GeV, we observe in the ZEUS detector events with a large rapidity gap in the hadronic final state. They occur in the region of small Bjorken x and are observed up to Q2 of 100 GeV2. They account for about 5% of the events with Q2 greater-than-or-equal-to 10 GeV2. Their general properties are inconsistent with the dominant mechanism of deep inelastic scattering, where color is transferred between the scattered quark and the proton remnant, and suggest that the underlying production mechanism is the diffractive dissociation of the virtual photon
Measurement of multiplicity and momentum spectra in the current fragmentation region of the Breit frame at HERA
No full textCharged particle production has been measured in Deep Inelastic Scattering (DIS) events using the ZEUS detector over a large range of Q^2 from 10 to 1280 GeV^2.
The evolution with Q of the charged multiplicity and scaled
momentum has been investigated in the current fragmentation region of the Breit frame. The data are used to study QCD coherence effects in DIS and are compared with corresponding e+e - data in order to test the universality of quark fragmentation
Measurement of total and partial photon proton cross-sections at 180-GeV center-of-mass energy.
No full textMeasurement of the cross section for the reaction γp → J/ψ p with the ZEUS detector at HERA
No full textThis paper reports the cross section measurements for the process ep --> e J/ψ p for Q^2 < 4 GeV^2 at sqrt(s) = 296 GeV, based on an integrated luminosity of about 0.5 pb^(-1), using the ZEUS detector. The J/ψ was detected in its e+e- and μ+μ− decay modes. The photoproduction cross section was measured to be 52 (+7-12) ± 10 nb at an average γp centre of mass energy of 67 GeV and 71 (+13-20) ± 12 nb at 114 GeV. The significant rise of the cross section compared to lower energy measurements is not in agreement with VDM models, but can be described by QCD inspired models if a rise in the gluon momentum density at low x in the proton is assumed
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