Search results for "Speed"
showing 10 items of 876 documents
Absence of a day-night asymmetry in the7Be solar neutrino rate in Borexino
2012
We report on a search for the day-night asymmetry of the Be-7 solar neutrino rate measured by Borexino at the Laboratori Nazionali del Gran Sasso (LNGS), Italy. The measured value, Adn=0.001 +- 0.012 (stat) +- 0.007 (syst), shows the absence of a significant asymmetry. This result alone rejects the so-called LOW solution at more than 8.5 sigma. Combined with the other solar neutrino data, it isolates the Large Mixing Angle (LMA) -- MSW solution at DeltaChi2 > 190 without relying on the assumption of CPT symmetry in the neutrino sector. We also show that including the day-night asymmetry, data from Borexino alone restricts the MSW neutrino oscillations to the LMA solution at 90% confidence l…
Conditions for statistical determination of the neutrino mass spectrum in radiative emission of neutrino pairs in atoms
2016
The photon spectrum in macrocoherent atomic de-excitation via radiative emission of neutrino pairs (RENP) has been proposed as a sensitive probe of the neutrino mass spectrum, capable of competing with conventional neutrino experiments. In this paper we revisit this intriguing technique in order to quantify the requirements for statistical determination of some of the properties of the neutrino spectrum, in particular the neutrino mass scale and the mass ordering. Our results are sobering. We find that, even under ideal conditions, the determination of neutrino parameters needs experimental live times of the order of days to years for several laser frequencies, assuming a target of volume o…
Measurement of Neutrino Oscillation Parameters from Muon Neutrino Disappearance with an Off-Axis Beam
2013
The T2K Collaboration reports a precision measurement of muon neutrino disappearance with an off-axis neutrino beam with a peak energy of 0.6 GeV. Near detector measurements are used to constrain the neutrino flux and cross section parameters. The Super-Kamiokande far detector, which is 295 km downstream of the neutrino production target, collected data corresponding to 3.01 x 10(20) protons on target. In the absence of neutrino oscillations, 205 +/- 17 (syst) events are expected to be detected while only 58 muon neutrino event candidates are observed. A fit to the neutrino rate and energy spectrum, assuming three neutrino flavors and normal mass hierarchy yields a best-fit mixing angle sin…
Video materiāli ar subtitriem angļu valodā lasīšanas ātruma un izpratnes paaugstināšanai 11. klasē
2020
Mūsdienās ir nepieciešama efektīva lasīšanas izpratne un ātrums, lai atrastu atbilstošu un patiesu informāciju, piemēram, laikrakstos, transporta grafikos un citos rakstveida avotos. Diplomdarba mērķis bija izpētīt, kā video materiālu ar angļu subtitriem pielietošana var palielināt lasīšanas ātrumu un izpratni 11. klasē. Pētījuma metode bija gadījuma pētījums ar 12 skolēnu izlasi. Datu vākšanas gaitā tika veikti skolēnu lasīšanas ātruma un izpratnes mērījumi, ievāktas atgriezeniskās saites anketas un veiktas daļēji strukturētas intervijas ar divām skolotājām. Pētījuma rezultātā tika atklāts, ka nedaudz paaugstinājās lasīšanas ātrums, bet pazeminājās teksta izpratne. Šajā gadījumā video mate…
La fatigue mentale : marqueurs électrophysiologiques et stratégies de compensation
2021
Mental fatigue is a common phenomenon in modern society, causing an alteration in both cognitive and physical performances. It can lead to an increased risk of accidents, a drop in productivity, and certain disorders such as depression. The objective of this thesis work was to study this phenomenon of mental fatigue by investigating more specifically its electrophysiological markers, and to find compensatory strategies to limit and/or avoid its deleterious effects.The first study identified brain activity modulations during a prolonged modified Stroop task. An increase in theta and alpha waves, as well as a decrease in N100 and P300 amplitude reflecting a decrease in attention were observed…
In-process tool force and rotation variation to control sheet thickness change in friction stir welding of magnesium alloys
2016
Two different in-process control strategies, developed in order to produce sound joints in AZ31 magnesium alloy by Friction Stir Welding on sheet blanks with a non-uniform thickness, are presented and compared. To this purpose, sheets with dip or hump were machined and welded by either changing the rotational speed or the tool plunging in order to keep constant the vertical force occurring during welding. The mechanical strength of the joints was measured in the zones where the sheets before welding were characterised by different thicknesses. The sheets welded by the two different strategies are characterized by very similar ultimate tensile strength values. Finally, the results showed tha…
Limiting neutrino magnetic moments with Borexino Phase-II solar neutrino data
2017
A search for the solar neutrino effective magnetic moment has been performed using data from 1291.5 days exposure during the second phase of the Borexino experiment. No significant deviations from the expected shape of the electron recoil spectrum from solar neutrinos have been found, and a new upper limit on the effective neutrino magnetic moment of $\mu_{\nu}^{eff}$ $<$ 2.8$\cdot$10$^{-11}$ $\mu_{B}$ at 90\% c.l. has been set using constraints on the sum of the solar neutrino fluxes implied by the radiochemical gallium experiments.Using the limit for the effective neutrino moment, new limits for the magnetic moments of the neutrino flavor states, and for the elements of the neutrino magne…
Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice.
2001
Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova2, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by mu…
Observation of high energy atmospheric neutrinos with the Antarctic muon and neutrino detector array
2002
The Antarctic Muon and Neutrino Detector Array (AMANDA) began collecting data with ten strings in 1997. Results from the first year of operation are presented. Neutrinos coming through the Earth from the Northern Hemisphere are identified by secondary muons moving upward through the array. Cosmic rays in the atmosphere generate a background of downward moving muons, which are about 10^6 times more abundant than the upward moving muons. Over 130 days of exposure, we observed a total of about 300 neutrino events. In the same period, a background of 1.05*10^9 cosmic ray muon events was recorded. The observed neutrino flux is consistent with atmospheric neutrino predictions. Monte Carlo simulat…
Atmospheric neutrino oscillations and tau neutrinos in ice
2010
The main goal of the IceCube Deep Core Array is to search for neutrinos of astrophysical origins. Atmospheric neutrinos are commonly considered as a background for these searches. We show here that cascade measurements in the Ice Cube Deep Core Array can provide strong evidence for tau neutrino appearance in atmospheric neutrino oscillations. Controlling systematic uncertainties will be the limiting factor in the analysis. A careful study of these tau neutrinos is crucial, since they constitute an irreducible background for astrophysical neutrino detection.