Final results on oscillation from the CHORUS experiment

Eşkut, E.; Topaksu, A. Kayis; Önengüt, G.; Beuzekom, M.G. van; Dantzig, R. van; Jong, M. de; Konijn, J.; Melzer, O.; Oldeman, R.; Pesen, E.; Poel, C.A.F.J. van der; Visschers, J.L.; Güler, M.; Köse, U.; Serin-Zeyrek, M.; Sever, R.; Tolun, P.; Zeyrek, M.; Armenise, N.; Cassol, Franca; Catanesi, M. G.; Serio, M. De; Muciaccia, M. T.; Radicioni, E.; Righini, P.; Simone, S.; Vivolo, L.; Bülte, A.; Winter, K.; Donckt, M. Vander; Vyver, B. Van de; Vilain, P.; Wilquet, G.; Saitta, B.; Capua, E. Di; Luppi, C.; Ishii, Y.; Kazuno, M.; Ogawa, S.; Shibuya, H.; Brünner, J.; Chizhov, M. V.; Cussans, D.; Doucet, M.; Fabre, J.; Flegel, W.; Hristova, I.; Kawamura, T.; Kolev, D.; Litmaath, M.; Meinhard, H.; Niu, E.; Øverås, H.; Panman, J.; Papadopoulos, I.; Ricciardi, S.; Rozanov, Alexandre; Saltzberg, D.; Tsenov, R.; Uiterwijk, J. W. E.; Weinheimer, C.; Wong, H. L. H.; Zucchelli, P.; Goldberg, J.; Chikawa, M.; Arık, E.; Mailov, A.; Song, Jeonghyeon; Yoon, C. S.; Kodama, K.; Ushida, N.; Aoki, S.; Hara, T.; Brooijmans, G.; Delbar, Th.; Favart, D.; Grégoire, G.; Hérin, J.; Kalinin, S.; Makhlioueva, I.; Artamonov, A.; Gorbunov, P.; Khovansky, V.; Shamanov, V.; Tsukerman, I.; Bonekämper, D.; Bruski, N.; Frekers, D.; Rondeshagen, D.; Wolff, Th.; Hoshino, K.; Kawada, J.; Komatsu, M.; Kotaka, Y.; Kozaki, Tatsuya; Miyanishi, M.; Nakamura, Makoto; Nakano, T.; Narita, Kentaro; Niu, K.; Niwa, K.; Nonaka, N.; Obayashi, Y.; Sato, Osamu; Toshito, T.; Buontempo, S.; Cocco, A. G.; D’Ambrosio, N.; Lellis, G. De; Rosa, G. De; Capua, F. Di; Ereditato, A.; Fiorillo, G.; Marotta, Anna; Messina, M.; Migliozzi, P.; Palladino, V.; Lavina, L. Scotto; Strolin, P.; Tioukov, V.; Nakamura, K.; Okusawa, T.; Capone, A.; Pedis, D. De; Liberto, S. Di; Dore, U.; Loverre, P.; Ludovici, L.; Maslennikov, A. L.; Mazzoni, M. A.; Piredda, G.; Rosa, G.; Santacesaria, R.; Satta, A.; Spada, F.; Barbuto, E.; Bozza, C.; Grella, G.; Romano, G.; Sirignano, C.; Sorrentino, S.; Sato, Yoshihiro; Tezuka, I.

doi:10.1016/j.nuclphysb.2007.10.023

Cited by 66 publications

(58 citation statements)

References 18 publications

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“…In figure 4 the 90% CL exclusion plot is reported in the ∆m 2 41 vs sin 2 2θ µτ parameter space. The most stringent limits of direct searches for ν µ → ν τ oscillations at short-baselines obtained by the NOMAD [14] and CHORUS [15] experiments are also shown. Our analysis stretches the limits on ∆m 2 41 down to 10 −2 eV 2 , extending the values explored with the τ appearance searches by about two orders of magnitude at large mixing, for sin 2 2θ µτ 0.5.…”

Section: % CLmentioning

confidence: 86%

See 1 more Smart Citation

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Agafonova¹,

Aleksandrov²,

Anokhina³

et al. 2015

J. High Energ. Phys.

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Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beamThe OPERA collaboration E-mail: alessandro.paoloni@lnf.infn.it, alessandra.pastore@ba.infn.it Abstract: The OPERA experiment, exposed to the CERN to Gran Sasso ν µ beam, collected data from 2008 to 2012. Four oscillated ν τ Charged Current interaction candidates have been detected in appearance mode, which are consistent with ν µ → ν τ oscillations at the atmospheric ∆m 2 within the "standard" three-neutrino framework. In this paper, the OPERA ν τ appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino. The OPERA collaboration 11 IntroductionThe OPERA experiment [1] operated in the CERN Neutrinos to Gran Sasso (CNGS) beam produced at CERN and directed towards the Gran Sasso Underground Laboratory of INFN (LNGS), 730 km away, where the detector is located. The experiment is unique in its capability to observe ν τ appearance on an event-by-event basis. Nuclear emulsion films instrumenting the target allow the detection of the short-lived τ lepton decay, and hence the identification of ν τ Charged Current (CC) interactions. The standard three-neutrino oscillation framework predicts ν µ → ν τ oscillations with close-to-maximal mixing at the so-called atmospheric scale, ∆m 2 32 ∼ 2.4 × 10 −3 eV 2 [2], i.e. in the oscillation parameters region discovered by detecting atmospheric neutrinos [3]. OPERA has observed four ν τ CC interaction candidate events [4][5][6][7], consistent with the expectation of the standard oscillation framework at this scale. This result represents the first direct evidence of ν µ → ν τ oscillation in appearance mode.In the present paper, limits are derived on the existence of a massive sterile neutrino. The excess of ν e (ν e ) observed by the LSND [8] and MiniBooNE [9] collaborations and the so-called reactor [10] and Gallium [11,12] neutrino anomalies are also interpreted as due to the existence of a fourth sterile neutrino with mass at the eV scale. In relation to this issue, it is worth mentioning that the effective number of neutrino-like species decoupled from the primeval plasma measured by the Planck collaboration is 3.15 ± 0.23 at 95% Confidence Level (CL) [13].Neutrino oscillations at large ∆m 2 have been searched for by several short baseline experiments. The most stringent limits on ν µ → ν τ oscillations were set by the NOMAD [14] and CHORUS [15] experiments, with high sensitivity for ∆m 2 values larger than 10 eV 2 .In the following, a short description of the OPERA experimental setup and of the procedure used to detect ν τ interactions is given, the data analysis is described and exclusion regions in the parameter space are derived.

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Section: % CLmentioning

confidence: 86%

“…OPERA 90% CL exclusion limits in the ∆m 2 41 vs sin 2 2θ µτ parameter space for the normal (NH, dashed red) and inverted (IH, solid blue) hierarchy of the three standard neutrino masses. The exclusion plots by NOMAD [14] and CHORUS [15] are also shown. Bands are drawn to indicate the excluded regions.…”

Section: % CLmentioning

confidence: 99%

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Agafonova¹,

Aleksandrov²,

Anokhina³

et al. 2015

J. High Energ. Phys.

Self Cite

View full text Add to dashboard Cite

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“…Being sin 2θ µτ the leading mixing term at short base line experiments, it allows a direct comparison with previous results of SBL experiment (NOMAD [17], CHORUS [18]). To extract limits on the sterile neutrino mixing parameters, we used the test statistic −2 ln λ p , where λ p is the profile likelihood ratio [4] defined as: plane, the asymptotic χ 2 distribution of the test statistic is assumed.…”

Section: Analysis Resultsmentioning

confidence: 84%

Search for sterile neutrino mixing in the muon neutrino to tau neutrino appearance channel with the OPERA detector

Tenti¹

2016

Proceedings of XVI International Workshop on Neutrino Telescopes — PoS(NEUTEL2015)

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The OPERA experiment observed ν µ → ν τ oscillations in the atmospheric sector. To this purpose the hybrid OPERA detector was exposed to the CERN Neutrinos to Gran Sasso beam from 2008 to 2012, at a distance of 730 km from the neutrino source. Charged-current interactions of ν τ were searched for through the identification of τ lepton decay topologies. The four observed ν τ interactions are consistent with the expected number of events in the standard three neutrino framework. In this work, we interpret the results in terms of the 3 + 1 sterile neutrino model using the GLoBES software. This analysis allows to constrain the effective mixing of the sterile and the new squared mass difference.

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“…For negative ∆m 2 41 values, the exclusion plots are similar but with hierarchies exchanged. In the plot, the results of CHORUS [24] and NOMAD [25], are also shown for comparison.…”

Section: Pos(neutel2015)010mentioning

confidence: 99%

Opera

Paoloni¹

2016

Proceedings of XVI International Workshop on Neutrino Telescopes — PoS(NEUTEL2015)

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The OPERA experiment is an hybrid detector made of nuclear emulsions and of electronic detectors. It has been designed to provide an evidence for ν µ → ν τ oscillations by detection of τ leptons in the parameter region identified from the observation of atmospheric neutrinos. The experiment took data from 2008 to 2012 on the CNGS beam. In this paper ν µ → ν τ oscillation results are presented, as well as results from other analyses. 1. Detector description and data taking.The OPERA experiment [1] has been designed to detect ν µ → ν τ oscillations through τ appearance. A sketch of the detector is shown in figure 1. Its location, inside the underground Gran Sasso laboratories, corresponding to a 732 km long baseline, together with the energy of the CNGS beam, on average 17 GeV, allows covering the ∆m 2 region of interest for the atmospheric neutrino oscillations, precisely investigated by SuperKamiokande [2], MINOS [3] and T2K [4].The detection of the τ leptons, with a decay path ∼ mm at the CNGS neutrino energies, is performed by means of the so-called ECC (Emulsion Cloud Chamber) technique, with the neutrino target made by 1 mm thick lead sheets alternated to nuclear emulsions, each one made by two 44 µm layers separated by a plastic base of 200 µm. A stack of 57 emulsion and 56 lead plates constitutes one brick. Bricks are arranged into walls, alternated to modules of x-y crossed scintillator strips, 2.6 cm wide, read-out by WLS fibers and multi-anode photomultipliers. The scintillator strips, the so-called Target Tracker [5] (TT), are used for the location of bricks with neutrino interactions.One supermodule is composed by 31 walls and TT layers, followed by a magnetic spectrometer for the rejection of the charm background. The magnetic spectrometer is an iron dipole [6] instrumented with Drift Tubes [7] and Resistive Plate Chambers [8]. The OPERA experiment is made by two supermodules, for a total initial target mass greater than 1.2 kt (corresponding to more than 140000 bricks). The detector was operated on the CNGS neutrino beam from 2008 to 2012, collecting a sample of 19505 contained neutrino interactions out of 17.97 × 10 19 pot. Bricks extracted for analysis were not replaced during data taking; the proton-on-target (pot) weighted average mass was 1.18 kt. The decommissioning of the detector has started in January 2015.2. ν µ → ν τ oscillation results.2.1 τ lepton identification.Neutrino interactions are selected in coincidence with the CNGS spills ("on-time" events). They are classified as CC-like (Charged Current or "1 µ") and NC-like (Neutral Current or "0 µ") PoS(NEUTEL2015)010 OPERA resultsAlessandro Paoloni according to the presence of one reconstructed muon in the electronic detectors. A classifier algorithm, OpCarac [9], is applied to identify the contained events, i.e. those with neutrino interactions inside the OPERA targets. For each contained event, bricks are ranked according to the probability of containing the neutrino interaction vertex by the brick-finding algorithm [10]. To preserve th...

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Final results on oscillation from the CHORUS experiment

Cited by 66 publications

References 18 publications

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Limits on muon-neutrino to tau-neutrino oscillations induced by a sterile neutrino state obtained by OPERA at the CNGS beam

Search for sterile neutrino mixing in the muon neutrino to tau neutrino appearance channel with the OPERA detector

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