Search results for "detectors"
showing 10 items of 2229 documents
Search for charged Higgs bosons decaying via H-+/- -> tau nu in t(t)over-bar events using pp collision data at root s=7 TeV with the ATLAS detector
2012
The results of a search for charged Higgs bosons are presented. The analysis is based on 4.6 fb(-1) of proton-proton collision data at root s = 7TeV collected by the ATLAS experiment at the Large Hadron Collider, using top quark pair events with a tau lepton in the final state. The data are consistent with the expected background from Standard Model processes. Assuming that the branching ratio of the charged Higgs boson to a tau lepton and a neutrino is 100%, this leads to upper limits on the branching ratio of top quark decays to a b quark and a charged Higgs boson between 5% and 1% for charged Higgs boson masses ranging from 90GeV to 160GeV, respectively. In the context of the m(h)(max) s…
A measurement of b+ and b-0 lifetimes using (d)over-bar-l(+) events
1995
A measurement of B meson lifetimes is presented using data collected from 1991 to 1993 by the DELPHI detector at the LEP collider. Samples of events with a D meson and a lepton in the same jet are selected where D¯0ℓ+ and D*ℓ+ events originate mainly from the semileptonic decays of B+ and B0 mesons, respectively. From the reconstructed B decay length and the estimated B momentum, taking into account the dilution due to B decays into D¯∗∗ℓ+v , the following B meson lifetimes and lifetime ratio are measured: τ(B+)=1.61+0.16−0.16(stat.)±0.12(syst.)psτ(B0)=1.61+0.14−0.13(stat.)±0.08(syst.)psτ(B+)/τ(B0)=1.00+0.17−0.15(stat.)±0.10(syst.) and an average lifetime of B+ and B0 mesons is obtained: τ(…
Search for a Supersymmetric Partner to the Top Quark in Final States with Jets and Missing Transverse Momentum at root s=7 TeV with the ATLAS Detector
2012
A search for direct pair production of supersymmetric top squarks ((t) over tilde (1)) is presented, assuming the (t) over tilde (1) decays into a top quark and the lightest supersymmetric particle, (chi) over tilde (0)(1), and that both top quarks decay to purely hadronic final states. A total of 16 (4) events are observed compared to a predicted standard model background of 13.5(-3.6)(+3.7) (4.4(-1.3)(+1.7)) events in two signal regions based on integral Ldt = 4.7 fb(-1) of pp collision data taken at root s = 7 TeV with the ATLAS detector at the LHC. An exclusion region in the (t) over tilde (1) versus (chi) over tilde (0)(1) mass plane is evaluated: 370 1) 10) similar to 0 GeV while m((t…
Search for lepton flavour number violating Z°-decays
1997
A search for lepton flavour number violating $Z^0$ decays in the channels \begin{center} $Z^0\rightarrow \mu\tau$,\\ $Z^0\rightarrow e\tau$, \\ $Z^0\rightarrow e\mu$, \\ \end{center} using the DELPHI detector with data collected during the 1991--94 LEP runs, is described. No signal was found. Upper limits at 95\% confidence level for the respective branching fractions of $1.2\times 10^{-5}$, $2.2\times 10^{-5}$, and $0.25\times 10^{-5}$, were obtained.
Measurement of gamma(b(b)over-bar)/gamma(had) using impact parameter measurements and lepton identification
1995
The partial decay width of theZ to bb¯quark pairs has been measured by the DELPHI detector at LEP.b-hadrons, containingb-quarks, were tagged by leptons with high transverse momentum relative to the hadron or by tracks with large impact parameters to the primary vertex.The ratio of the numbers of events with a single such tag to those with two tags was used to estimate the efficiency of the method and to reduce the systematic uncertainty. Combining all methods, the value: Γbb¯Γhad=0.2210±0.0033±0.0003(model)±0.0014(Γcc¯) was found, where the third error corresponds to a±8% uncertainty on the cc production width. A maximum likelihood in to the single and di-lepton distributions gave the branc…
IAXO - The International Axion Observatory
2013
The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of a few 10^{-12} GeV^{-1}, i.e. 1-1.5 orders of magnitude beyond sensitivities achieved by the currently most sensitive axion helioscope, the CERN Axion Solar Telescope (CAST). Crucial factors in improving the sensitivity for IAXO are the increase of the magnetic field volume together with the extensive use of x-ray focusing optics and low background detectors, innovations already successfully tested at CAST. Electron-coupled axions invoked to explain the white dwarf cooling, relic axions, and a large variety of more generic axion-like particles (ALPs) along…
Streuung von mittelschnellen Elektronen an Kunststoff-Folien mit eingelagerten Schwermetallatomen
1962
Scattering has been observed of 70-keV electrons by Kollodium-foils containing elements of high atomic number (lead). The contents of lead are determined and the kind of distribution of lead in the foil is described. The differential cross-section as a function of the angle of scattering approximates the cross-section calculated by Sherman with lower contents of lead of the foils. Remaining deviations can be explained by screening-effects of the electron cloud.
Measurement of Event Shape and Inclusive Distributions at $\sqrt{s} =$ 130 and 136 GeV
1997
Inclusive charged particle and event shape distributions are measured using 321 hadronic events collected with the DELPHI experiment at LEP at effective centre of mass energies of 130 to 136 GeV. These distributions are presented and compared to data at lower energies, in particular to the precise Z data. Fragmentation models describe the observed changes of the distributions well. The energy dependence of the means of the event shape variables can also be described using second order QCD plus power terms. A method independent of fragmentation model corrections is used to determine $\alpha_s$ from the energy dependence of the mean thrust and heavy jet mass. It is measured to be: % %\alpha_s…
Initial results on energy resolution of the NEXT-White detector
2018
One of the major goals of the NEXT-White (NEW) detector is to demonstrate the energy resolution that an electroluminescent high pressure xenon TPC can achieve for high energy tracks. For this purpose, energy calibrations with 137Cs and 232Th sources have been carried out as a part of the long run taken with the detector during most of 2017. This paper describes the initial results obtained with those calibrations, showing excellent linearity and an energy resolution that extrapolates to approximately 1% FWHM at Q$_{\beta\beta}$.
The ATLAS Data Acquisition and High Level Trigger system
2016
Journal of Instrumentation 11(06), P06008 (2016). doi:10.1088/1748-0221/11/06/P06008