First observation of multiple volume reflection by different planes in one bent silicon crystal for high-energy protons

Multiple volume reflection by different planes in a bent silicon crystal with its axis orientation close to the beam direction was observed for the first time for 400 GeV/c protons at the CERN SPS. The proton beam was deflected to the side opposite to the crystal bend by an angle of about 67 urad, which is five times larger than in a single volume reflection by the (110) bent planes. The registered efficiency of one side deflection was about 84%. It was shown that multiple volume reflection transforms to a single volume reflection when the orientation angle of the axis relative to the beam direction is increased

Electroweak parameters of the z0 resonance and the standard model

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Search for the t and b′ quarks in hadronic decays of the Z0 boson

[Abstract

The reaction e+ e- ---> gamma gamma (gamma) at Z0 energies

The total and differential cross-sections for the reaction e+e- → γγ(γ) are measured at centre of mass energies around 91 GeV using an integrated luminosity of 4.7 pb-1. The aggreement with QED prediction is good. Consequently there is no evidence for non-standard channels which would have the same experimental signature. The lower limits on the QED cuttoff parameters are Λ+ > 113 GeV and Λ- > 95 GeV. An upper limit on the effective coupling between a possible excited electron and the gamma is derived. At 95% confidence level the branching ratios for Z0 decay into π0γ, ηψ and γγγ are below 1.5 × 10-4, 2.8 × 10-4 and 1.4 × 10-4 respectively.0info:eu-repo/semantics/publishe

A Measurement of sin**2 theta(W) from the charge asymmetry of hadronic events at the Z0 peak

Abstract View references (24)The weak mixing angle has been measured from the charge asymmetry of hadronic events with two different approaches using the DELPHI detector at LEP. Both methods are based on a momentum-weighted charge sum to determine the jet charge in both event hemispheres. In a data sample of 247 300 multihadronic Z0 decays a charge asymmetry of 〈QF〉 - 〈QB〉 = -0.0076±0.0012(stat.)±0.0005(exp. syst.)±0.0014(frag.) and a raw forward-backward asymmetry of Araw FB = -0.0109±0.0020(stat.)±0.0010(exp. syst.)±0.0017(frag.) have been measured. This result corresponds to a value of sinθeff=0.2345±0.0030(exp.)±0.0027(frag.) ,sin2θMS=0.2341±0.0030(exp.)±0. 0027(frag.) and to sin2θW=1-m2 W/m2 Z=0.2299± 0.0030(exp.)±0.0027(frag.)±0.0028(theor.). The experimental error is the quadratic sum of the statistical and the experimental systematic error and the theoretical error originates from a value of mt=130±40 GeV/c2 and a range of mH from 45 GeV/c2 to 1000 GeV/c2.0info:eu-repo/semantics/publishe