arXiv subjects

A. Olchevsky

Publications and source records attributed to A. Olchevsky.

3 recordsLinked to original sources

arXiv2018

Latest results of the OPERA experiment on nu-tau appearance in the CNGS neutrino beam

OPERA is a long-baseline experiment designed to search for $ν_μ\toν_τ$ oscillations in appearance mode. It was based at the INFN Gran Sasso laboratory (LNGS) and took data from 2008 to 2012 with the CNGS neutrino beam from CERN. After the discovery of $ν_τ$ appearance in 2015, with $5.1σ$ significance, the criteria to select $ν_τ$ candidates have been extended and a multivariate approach has been used for events identification. In this way the statistical uncertainty in the measurement of the oscillation parameters and of $ν_τ$ properties has been improved. Results are reported.

hep-ex↗

arXiv2018

Final results of the OPERA experiment on $ν_τ$ appearance in the CNGS beam

The OPERA experiment was designed to study $ν_μ\toν_τ$ oscillations in appearance mode in the CNGS neutrino beam. In this letter we report the final analysis of the full data sample collected between 2008 and 2012, corresponding to $17.97\cdot 10^{19}$ protons on target. Selection criteria looser than in previous analyses have produced ten $ν_τ$ candidate events, thus reducing the statistical uncertainty in the measurement of the oscillation parameters and of $ν_τ$ properties. A multivariate approach for event identification has been applied to the candidate events and the discovery of $ν_τ$ appearance is confirmed with an improved significance level of 6.1 $σ$. $Δm^2_{23}$ has been measured, in appearance mode, with an accuracy of 20%. The measurement of $ν_τ$ CC cross-section, for the first time with a negligible contamination from $\barν_τ$, and the first direct observation of the $ν_τ$ lepton number are also reported.

hep-ex↗

arXiv2015

Discovery of tau neutrino appearance in the CNGS neutrino beam with the OPERA experiment

The OPERA experiment was designed to search for $ν_μ \rightarrow ν_τ$ oscillations in appearance mode, i.e. by detecting the $τ$-leptons produced in charged current $ν_τ$ interactions. The experiment took data from 2008 to 2012 in the CERN Neutrinos to Gran Sasso beam. The observation of $ν_μ \rightarrow ν_τ$ appearance, achieved with four candidate events in a sub-sample of the data, was previously reported. In this paper, a fifth $ν_τ$ candidate event, found in an enlarged data sample, is described. Together with a further reduction of the expected background, the candidate events detected so far allow assessing the discovery of $ν_μ\rightarrow ν_τ$ oscillations in appearance mode with a significance larger than 5 $σ$.

hep-ex↗