1,427 research outputs found
Neutron production from 158 GeV/c per nucleon lead ions on thin copper and lead targets in the angular range 30-135 deg
No full textThe neutron emission from 5, 10 and 20 mm thick lead and 10 and 20 mm thick copper targets bombarded by a lead ion beam with momentum of 158 GeV/c per nucleon were measured at the CERN Super Proton Synchrotron. The neutron yield and spectral fluence per incident ion on target were measured with an extended range Bonner sphere spectrometer in the angular range 30-135 deg. with respect to beam direction. Monte Carlo simulations with the FLUKA code were performed to establish a guess spectrum for the unfolding of the experimental data. The results have shown that, lacking Monte Carlo radiation transport codes dealing with ions with masses larger than 1 amu, a reasonable prediction can be carried out by scaling the result of a Monte Carlo calculation for protons by the projectile mass number to the power of 0.85-0.95 for a lead target and 0.88-1.03 for a copper target
A vertex reconstruction toolkit and interface to generic objects (VERTIGO)
No full textA proposal is made for the design and implementation of a detector-independent Vertex Reconstruction Toolkit (VERTIGO). It aims at re-using existing state-of-the-art algorithms for geometric vertex finding and fitting by both linear and robust estimation methods; kinematic constraints will also be included for the benefit of complex multi-vertex topologies. The design is based on modern object-oriented techniques. A core (RAVE) is surrounded by a shell of interfaces and a set of analysis & debugging tools. The implementation follows an open source approach and is easily adaptable to future standards
Design of the Advanced Metadata Service System with AMGA
No full textThe Belle II experiment is expected to produce 50 times more data than the existing Belle experiment. Such huge data production requires not only scalability with respect to the storage service but also scalability regarding the metadata service. There has already been a metadata service at the Belle experiment, but it is not proper for the Belle II experiment because it has scalability problems and it is not intended to be used in a distributed grid environment. To deal with these issues, we designed an advanced metadata service system based on AMGA, which provides efficient and scalable metadata searching. We have built testbed sites to test the correctness, performance and scalability of the advanced metadata service system, and it has been proved to be able to provide efficient metadata searching for the Belle II experimen
An amplitude analysis of the system produced in the reaction at 10 GeV/c
No full textWe present results on an amplitude analysis of the K+K- system produced in the reaction π-p→K+K-n from threshold up to 2.2 GeV. The branching ratios of f0 and f' to KK have been determined. In the low mass region of the KK system the observation of an S-wave enhancement at 1.3 GeV and the interference of the f0-A2-f' mesons are studied. We observe a 3- structure in the mass region of 1.7 GeV which is consistent with g0 production. With this interpretation the branching ratio g→KK has been determined. Evidence for a new structure in the Jp = 2+ wave around 1.8 GeV with a width of ∼200 MeV is presented
Bose-Einstein Correlations in W ^ + W ^ - events at LEP2
No full textBose-Einstein correlations (BEC) between final state particles in the reaction e+e- → W+W- → q1q2̄q3q4̄ have been studied. Data corresponding to a total integrated luminosity of 550 pb -1, recorded by the DELPHI detector at centre-of-mass energies ranging from 189 to 209 GeV, were analysed. An indication for inter-W BEC between like-sign particles has been found at the level of 2.4 standard deviations of the combined statistical and systematic uncertainties. © Springer-Verlag / Società Italiana di Fisica 2005.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Study of W-boson polarisations and triple gauge boson couplings in the reaction e(+)e(-)-> W+W- at LEP 2
No full textA determination of the single W spin density matrix (SDM) elements in the reaction e(+)e(-) -> W+W--> l nu q (q) over bar (l=e/mu) is reported at centre-of-mass energies between 189 and 209GeV. The data sample used corresponds to an integrated luminosity of 520pb(-1) taken by DELPHI between 1998 and 2000. The single W SDM elements, rho(W +/-)(tau tau') (tau,tau'=+/- 1 or 0), are determined as a function of the W- production angle with respect to the e(-) beam direction and are obtained from measurements of the W decay products by the application of suitable projection operators, Lambda(tau tau'), which assume the V-A coupling of the W-boson to fermions.
The measured SDM elements are used to obtain the fraction of longitudinally polarised Ws, with the result:
sigma(L)/sigma(tot) = 24.9 +/- 4.5 (stat) +/- 2.2 (syst)%
at a mean energy of 198 GeV. The SDM elements are also used to determine the triple gauge couplings Delta g(1)(Z), Delta kappa(gamma), lambda(gamma) and g(4)(Z), (kappa) over tilde (Z) and (lambda) over tilde (Z). For the CP-violating couplings the results of single parameter fits are:
g(4)(Z) = -0.39(-0.20)(+0.19)
(kappa) over tilde (Z) = -0.09(-0.05)(+0.08)
(lambda) over tilde (Z) = -0.08 +/- 0.07.
The errors are a combination of statistical and systematic errors. All results are consistent with the Standard Model
Measurement of the e+ e- ---> W+ W- gamma cross-section and limits on anomalous quartic gauge couplings with DELPHI.
No full textW(+)W(-)gamma production at LEP2 is studied using data collected with the DELPHI detector at centre-of-mass energies between 189 GeV and 209 GeV, corresponding to an integrated luminosity of about 600 pb(-1). Cross-sections are measured for the production of W+W- with a hard, central and isolated photon in the final state, and are found to be compatible with the Standard Model prediction. The photon energy spectra are used to derive limits on anomalous contributions to the W(+)W(- )Z(o)gamma and W(+)W(-)gammagamma vertices
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