The OPERA detector, designed to search for
ν
μ
→
ν
τ
oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the ...analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio
R
μ
≡
N
μ
+
/
N
μ
-
was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1–20 TeV investigated by OPERA,
R
μ
is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to
200
TeV/nucleon primary energy.
The crystal structure of the mono- and heterometallic complexes MEn3L2 (M = Zn2+,M2+) and MEn3 CdL32 (M = Cd2+, Zn2+, Ni2+) containing ethylenediamine (En) molecules and diethyldithio-carbamate ions ...(L = (C2H5)2NCS2−) is investigated. The three heterometallic complexes are isostructural; their structure consists of discrete mononuclear ions. In the MEn32+ cation, the central M atom lies on the twofold axis; therefore, two of the three metallocycles MN2C2 of the MEn32+ cation are independent. One of the two has a gosh-configuration. In the coordinated En molecules, the N-M-N chelate angles are 77.0 and 82.9‡ (M = Cd2+); 80.0 and 80.5‡ (M = Zn2+); 79.7 and 80.8‡ (M = Ni2+). The nitrogen atoms form a distorted octahedron around M. The average M-N bond lengths for the complexes are 2.35, 2.19, and 2.16 å for M = Cd2+, Zn2+, and Ni2+, respectively. All the atoms of the CdL3− complex anion are in the general position; the central atom coordinates three cyclic bidentate L− ligands. The S atoms form a distorted trigonal prism, where the S...S distances in the vertical edges are nearly the same in all the complexes (2.94(1)-3.00(2) å). It was shown by1H,14N, and113Cd NMR that the ionic complexes ZnEn3L2 and CdEn3CdL32 in solution are transformed into nonelectrolyte type mixed-ligand complexes.
A
bstract
The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the
ν
μ
→
ν
τ
channel, via the detection of the
τ
-leptons ...created in charged current ν
τ
interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first
ν
τ
candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional
ν
τ
candidate has been observed. The significance of the two events in terms of a
ν
μ
→
ν
τ
oscillation signal is of 2.40
σ
.
The OPERA detector, designed to search for $\nu_{\mu} \to \nu_{\tau}$ oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale ...cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio $R_{\mu} \equiv N_{\mu^+}/N_{\mu^-}$ was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1-20 TeV investigated by OPERA, $R_{\mu}$ is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to $200$ TeV/nucleon primary energy.
The OPERA experiment Agafonova, N.; Aleksandrov, A.; Aoki, S. ...
Nuclear and particle physics proceedings,
10/2015, Letnik:
267-269
Journal Article
Recenzirano
Odprti dostop
The OPERA experiment was designed to study νμ→ντ oscillations in appearance mode using the CERN to Gran Sasso high energy neutrino beam. From 2008 to 2012, 19505 CNGS neutrino interactions were ...recorded in the OPERA detector. At the present status of the analysis, 4 ντ candidate events have been observed, establishing the oscillation mechanism in the atmospheric sector with a significance of 4.2 σ. The oscillation analysis will be presented in detail and the candidate events will be described. The final measurement of the atmospheric muon charge ratio in the TeV region will be also reported.
A bstract A first result of the search for ν μ → ν e oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of ...ν e in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters θ new and $ \varDelta m_{\mathrm{new}}^2 $ suggested by the LSND and MiniBooNE experiments. For large $ \varDelta m_{\mathrm{new}}^2 $ values ( > 0.1 eV 2 ), the OPERA 90% C.L. upper limit on sin 2 (2 θ new ) based on a Bayesian statistical method reaches the value 7 . 2 × 10 −3 .
Deposition and characterization of films of ZnS, EuS and ZnS:Eu are described. The films have been prepared by chemical vapor deposition using new volatile complex compounds, dithiocarbamates of Zn ...and Eu, as precursors. Characterization includes X-ray diffraction, chemical analysis of the film composition, Raman spectroscopy, ellipsometry, and spectrophotometry. The spatial chemical homogeneity of the films has been determined using a recently developed method of differential dissolution and found to be uniform. Doping of ZnS by Eu with dopant concentration up to 0.3 at.% has been achieved. Effects of Eu doping on structural and optical properties of the films are presented.
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