Chiasma Syndrome in Acromegalic Patients – Correlation of Neuroradiologic and Neuroophthalmologic Findings

The study evaluated neuroophthalmologic and computerized tomography (CT) findings in 100 patients with somatotrophic adenoma and clinical picture of acromegaly, who underwent transsphenoidal adenomectomy. Prior to the surgery, visual field was normal in 77 patients. The diameter of adenoma in these patients ranged from 8 to 30 mm on CT, and the average value was 13.5 mm. Various kinds of visual field disturbances were present in 23 patients. The diameter of their adenomas ranged between 18 to 35 mm, with the average of 24.7 mm. Compared to visual field defects, CT findings of suprasellar adenoma extension were better correlated with chiasma syndrome (p < 0.001). All patients with suprasellar mass greater than 10 mm had chiasma syndrome. Degenerative adenoma changes (hemorrhagic necrosis), which precipitate abrupt increase in size of the tumor, were more frequently seen in patients with chiasma syndrome. The incidence of chiasma syndrome directly correlates with the degree of suprasellar extension of the tumor

Prospects for the measurement of muon-neutrino disappearance at the FNAL-Booster

Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long-standing problem of new physics beyond the Standard Model. The recent measurement of the mixing angle $\theta_{13}$ in the standard mixing oscillation scenario encourages us to pursue the still missing results on leptonic CP violation and absolute neutrino masses. However, puzzling measurements exist that deserve an exhaustive evaluation. The NESSiE Collaboration has been setup to undertake conclusive experiments to clarify the muon-neutrino disappearance measurements at small $L/E$, which will be able to put severe constraints to models with more than the three-standard neutrinos, or even to robustly measure the presence of a new kind of neutrino oscillation for the first time. To this aim the use of the current FNAL-Booster neutrino beam for a Short-Baseline experiment has been carefully evaluated. This proposal refers to the use of magnetic spectrometers at two different sites, Near and Far. Their positions have been extensively studied, together with the possible performances of two OPERA-like spectrometers. The proposal is constrained by availability of existing hardware and a time-schedule compatible with the CERN project for a new more performant neutrino beam, which will nicely extend the physics results achievable at the Booster. The possible FNAL experiment will allow to clarify the current $\nu_{\mu}$ disappearance tension with $\nu_e$ appearance and disappearance at the eV mass scale. Instead, a new CERN neutrino beam would allow a further span in the parameter space together with a refined control of systematics and, more relevant, the measurement of the antineutrino sector, by upgrading the spectrometer with detectors currently under R&D study.Comment: 76 pages, 52 figure

Determination of the muon charge sign with the dipolar spectrometers of the OPERA experiment

The OPERA long-baseline neutrino-oscillation experiment has observed the direct appearance of $\nu_\tau$ in the CNGS $\nu_\mu$ beam. Two large muon magnetic spectrometers are used to identify muons produced in the $\tau$ leptonic decay and in $\nu_\mu^{CC}$ interactions by measuring their charge and momentum. Besides the kinematic analysis of the $\tau$ decays, background resulting from the decay of charmed particles produced in $\nu_\mu^{CC}$ interactions is reduced by efficiently identifying the muon track. A new method for the charge sign determination has been applied, via a weighted angular matching of the straight track-segments reconstructed in the different parts of the dipole magnets. Results obtained for Monte Carlo and real data are presented. Comparison with a method where no matching is used shows a significant reduction of up to 40\% of the fraction of wrongly determined charges.Comment: 10 pages. Improvements in the tex

Procedure for short-lived particle detection in the OPERA experiment and its application to charm decays

The OPERA experiment, designed to perform the first observation of $\nu_\mu \rightarrow \nu_\tau$ oscillations in appearance mode through the detection of the $\tau$ leptons produced in $\nu_\tau$ charged current interactions, has collected data from 2008 to 2012. In the present paper, the procedure developed to detect $\tau$ particle decays, occurring over distances of the order of 1 mm from the neutrino interaction point, is described in detail. The results of its application to the search for charmed hadrons are then presented as a validation of the methods for $\nu_\tau$ appearance detection

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

The OPERA experiment, exposed to the CERN to Gran Sasso $\nu_\mu$ beam, collected data from 2008 to 2012. Four oscillated $\nu_\tau$ Charged Current interaction candidates have been detected in appearance mode, which are consistent with $\nu_\mu \to \nu_\tau$ oscillations at the atmospheric $\Delta m^2$ within the "standard" three-neutrino framework. In this paper, the OPERA $\nu_\tau$ appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino.Comment: 11 pages, 4 figures; reference to Planck result updated in the Introduction. Submitted to JHE

Observation of nu_tau appearance in the CNGS beam with the OPERA experiment

The OPERA experiment is searching for nu_mu -> nu_tau oscillations in appearance mode i.e. via the direct detection of tau leptons in nu_tau charged current interactions. The evidence of nu_mu -> nu_tau appearance has been previously reported with three nu_tau candidate events using a sub-sample of data from the 2008-2012 runs. We report here a fourth nu_tau candidate event, with the tau decaying into a hadron, found after adding the 2012 run events without any muon in the final state to the data sample. Given the number of analysed events and the low background, nu_mu -> nu_tau oscillations are established with a significance of 4.2sigma.Comment: Submitted to Progress of Theoretical and Experimental Physics (PTEP

Search for sterile neutrinos in muon neutrino disappearance mode at FNAL

The NESSiE Collaboration has been setup to undertake a conclusive experiment to clarify the {\em muon--neutrino disappearance} measurements at short baselines in order to put severe constraints to models with more than the three--standard neutrinos. To this aim the current FNAL--Booster neutrino beam for a Short--Baseline experiment was carefully evaluated by considering the use of magnetic spectrometers at two sites, near and far ones. The detector locations were studied, together with the achievable performances of two OPERA--like spectrometers. The study was constrained by the availability of existing hardware and a time--schedule compatible with the undergoing project of multi--site Liquid--Argon detectors at FNAL. The settled physics case and the kind of proposed experiment on the Booster neutrino beam would definitively clarify the existing tension between the $\nu_{\mu}$ disappearance and the $\nu_e$ appearance/disappearance at the eV mass scale. In the context of neutrino oscillations the measurement of $\nu_{\mu}$ disappearance is a robust and fast approach to either reject or discover new neutrino states at the eV mass scale. We discuss an experimental program able to extend by more than one order of magnitude (for neutrino disappearance) and by almost one order of magnitude (for antineutrino disappearance) the present range of sensitivity for the mixing angle between standard and sterile neutrinos. These extensions are larger than those achieved in any other proposal presented so far.Comment: 19 pages, published in EPJ

The OPERA experiment

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

More results from the OPERA experiment

The OPERA experiment reached its main goal by proving the appearance of vτ in the CNGS vμ beam. Five vτ candidates were detected with a S/B ratio of ∼ 10, allowing to reject the null hypothesis at 5.1σ. The search has been extended by loosening the selection criteria in order to improve the statistical uncertainty. One of the vτ candidates selected with the new strategy shows a double vertex topology and, after a dedicated multivariate analysis, is compatible with being a vTτ interaction with charm production. Based on the enlarged data sample the estimation of Δm223 in appearance mode is being performed. The search for ve interactions has been extended over the full data set with a more than twofold increase in statistics: data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. The implications of the electron neutrino sample in the framework of the 3+1 sterile mode will lead to exclusion limits on sin2 2θμe. Finally, the analysis of the annual modulation of cosmic muons is introduced