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Euclid is an ESA mission designed to understand why the expansion of the Universe is accelerating and what is the nature of the dark energy responsible for this acceleration. By measuring two cosmological probes simultaneously, the Weak Gravitational Lensing and the Galaxy Clustering (BAO and Redshift-Space distorsions), Euclid will constrain dark energy, general relativity, dark matter and the initial conditions of the Universe with unprecedented accuracy. Euclid will be equipped with a 1.2 m diameter SiC mirror telescope feeding 2 instruments: the visible imager and the Near-Infrared Spectro-Photometer. Here the Euclid's observation probes and main aims are recalled, and the NISP instrument and expected performances are presented.

A bstract The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino interaction target, made of Emulsion Cloud Chambers, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by π 0 s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate m 4 is introduced. At high Δ m 41 2 (≳0.1 eV 2 ), an upper limit on sin 2 2 θ μe is set to 0.021 at 90% C.L. and Δ m 41 2  ≳ 4 × 10 − 3 eV 2 is excluded for maximal mixing in appearance mode.

An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the OPERA target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with c c ¯ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a ν τ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated.

The OPERA experiment was designed to search for \\[\\nu _{\\mu } \\rightarrow \\nu _{\\tau }\\] oscillations in appearance mode through the direct observation of tau neutrinos in the CNGS neutrino beam. In this paper, we report a study of the multiplicity of charged particles produced in charged-current neutrino interactions in lead. We present charged hadron average multiplicities, their dispersion and investigate the KNO scaling in different kinematical regions. The results are presented in detail in the form of tables that can be used in the validation of Monte Carlo generators of neutrino–lead interactions.

An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the OPERA target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with [Formula omitted] pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a [Formula omitted] CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated.

The OPERA experiment was designed to discover the v τ appearance in a v μ beam, due to neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of a nuclear photographic emulsion/lead target with a mass of about 1.25 kt, complemented by electronic detectors. It was exposed from 2008 to 2012 to the CNGS beam: an almost pure v μ beam with a baseline of 730 km, collecting a total of 1.8·10 20 protons on target. The OPERA Collaboration eventually assessed the discovery of v μ → v τ oscillations with a statistical significance of 6.1 σ by observing ten v τ CC interaction candidates. These events have been published on the Open Data Portal at CERN. This paper provides a detailed description of the v τ data sample to make it usable by the whole community. Measurement(s) tau neutrino Technology Type(s) detector Sample Characteristic - Environment neutrino beam Sample Characteristic - Location Laboratori Nazionali del Gran Sasso Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.14979858

This paper describes a new νe identification method specifically designed to improve the low-energy ($\\lt {30}\\, {\\rm GeV}$) νe identification efficiency attained by enlarging the emulsion film scanning volume with the next-generation emulsion readout system. A relative increase of 25–70% in the νe low-energy region is expected, leading to improvements in the OPERA sensitivity to neutrino oscillations in the framework of the 3 + 1 model. The method is applied to a subset of data where the detection efficiency increase is expected to be more relevant, and one additional νe candidate is found. The analysis combined with the ντ appearance results improves the upper limit on sin 22θμe to 0.016 at 90% C.L. in the MiniBooNE allowed region $\\Delta m^2_{41} \\sim {0.3}\\, {\\rm eV}^{2}$.

Section Analysis, line 9: sub-sample of 818 events becomes sub-sample of 817 events.

This paper describes a new$\\nu_e$identification method specifically designed to improve the low-energy ( $< 30\\,\\mathrm{GeV}$ )$\\nu_e$identification efficiency attained by enlarging the emulsion film scanning volume with the next generation emulsion readout system. A relative increase of 25-70% in the$\\nu_e$low-energy region is expected, leading to improvements in the OPERA sensitivity to neutrino oscillations in the framework of the 3 + 1 model. The method is applied to a subset of data where the detection efficiency increase is expected to be more relevant, and one additional$\\nu_e$candidate is found. The analysis combined with the$\\nu_\\tau$appearance results improves the upper limit on$\\sin^2 2\\theta_{\\mu e}$to 0.016 at 90% C.L. in the MiniBooNE allowed region$\\Delta m^2_{41} \\sim 0.3\\,\\mathrm{eV}^2$ .

The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino interaction target, made of Emulsion Cloud Chambers, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by π ⁰ s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate m ₄is introduced. At high Δm ₄₁²(≳0.1 eV ² ), an upper limit on sin ²2θ _(μe)is set to 0.021 at 90% C.L. and Δm ₄₁² ≳ 4 × 10 ⁻ ³eV ²is excluded for maximal mixing in appearance mode.