Uno de los descubrimientos más importantes de los últimos años en física de partículas ha sido el descubrimiento de la oscilación de neutrinos. Este descubrimiento ha motivado la creación varios experimentos para medir con alta precisión los parámetros de oscilación de los neutrinos. Para hacer estos experimentos de alta precisión es crucial tener un buen conocimiento de las interacciones de neutrino-nucleón, lo cual es la principal motivación del presente estudio. La medida de la sección eficaz de interacciones de neutrino en el régimen de energías de pocos GeV es complicada ya que en esta región las diferentes interacciones son tan parecidas que se superponen en los observables cinemáticos. En esta tesis se presenta la medida de la sección eficaz relativa de producción multi-piones respecto a la interacción cuasi-elástica en corrientes cargadas, obtenida a partir de los datos del experimento K2K. K2K es el primer experimento de oscilación de neutrinos muónicos a larga distancia donde tanto la producción como la detección de neutrinos se hacen en el laboratorio. La producción de neutrinos y el detector cercano se encuentran en Tsukuba (Japón) y a 250 Km, en Kamioka (Japón), se encuentra el detector lejano. Para la medida multi-piones se han utilizado los datos recogidos por SciBar y MRD en el detector cercano. SciBar es un detector formado por barras centelladoras con el que se reconstruye el paso de las partículas producidas por la interacción de neutrinos en su interior. MRD es un detector de muones que nos permite reconstruir los muones. Los neutrinos pueden interaccionar de diferentes formas con la materia. Si el neutrino interacciona con un neutrón produciendo un muón y un protón, la interacción se llama cuasi-elástica. Si en la interacción se produce un muón, un nucleón y dos o más piones, la interacción se llama de multi-pion. Ambas interacciones son de corrientes cargadas, ya que el neutrino muónico se convierte en un muón cargado en la interacción. Para el análisis solo se han seleccionado eventos con al menos un muón producido en el volumen fiducial de SciBar y que también sea detectado en MRD. A partir de estos eventos se han reconstruido seis observables para la identificación de multi-piones y cuasi-elásticos y se han combinado para crear sendas funciones de asimetría de verosimilitud. Estas funciones tiene la propiedad de asignar valores bajos a eventos cuasi-elásticos, tiende a dar valores altos a eventos multi-pion y valores intermedios a las otras interacciones. Comparando estas funciones en datos y Monte Carlo se han obtenido las secciones eficaces relativas de multi-piones respecto cuasi-elasticos para las regiones de energías de 0.5-2.5 GeV y 2.5-5.0 GeV. En la medida se han evaluado los posibles errores sistemáticos debido a imprecisiones en el flujo de neutrinos, en la simulación de efectos nucleares, en la respuesta del detector y en los procesos de reconstrucción. Como resultado se ha obtenido que la sección eficaz relativa de multi-piones respecto de cuasi-elasticos es 0.30 +- 0.07 (est.) +- 0.15 (sis.) para energías de neutrino comprendidas entre 0.5 y 2.5 GeV y 3.9 +- 0.6 (est.) + 1.4 - 1.2 (sis.) para energías de neutrino comprendidas entre 2.5 y 5.0 GeV. / One of the most important discoveries on last years in particle physics is the neutrino oscillation.This discovery triggered the development of new experiments to measure the neutrino oscillation parameters with better accuracy.For these high precision experiments it is crucial to have a good knowledge of neutrino-nucleus interactions, and this is the main motivation for the work here presented.The measurement of neutrino interaction cross sections on the few GeV regime is complicated since the neutrino interactions are so similar that kinematic observables overlaps.In this thesis the measurement of the relative Multi-pion neutrino interaction cross section with respect to the quasielastic interaction with charged currents is presented. This measurement has been made with K2K data from the SciBar detector.K2K is the first long-baseline neutrino oscillation experiment ever done with muon neutrino beam.On that kind of experiment, both the source and the detection of neutrinos are controlled in the lab.Production and detection of near neutrinos is made in Tsukuba (Japan) and 250 Km away seats the far detector, in Kamioka (Japan). For the multi-pion measurement, data from the SciBar and MRD near detectors has been used. SciBar is a detector made off scintillating bars that is able to reconstruct the track of particles produced on neutrino interactions inside the detector. MRD is a muon detector that allows us to reconstruct muon energy and angle.Neutrinos interacts with matter in different ways. When a neutrino interacts with a neutron producing a muon and a proton, the interaction is called quasielastic. When the interaction produces a muon and two or more pions, the interaction is called multi-pion. Both interactions are charged current interactions, since the neutrino becomes a charged particle in the interaction.Only the events with a muon detected in MRD and starting in SciBar fiducial volume has been used for the analysis. With these events, six observables has been reconstructed to identify multi-pions and quasielastic interactions. These observables has been combined to create a likelihood asymmetry function that has the property to assign low values to quasielastic events and tend to assign high values to multi-pion events. Other interactions get middle values.From the fit of the asymmetry function from Monte Carlo to data, the multi-pion relative cross section respect to quasielastics has been obtained for the neutrino energy regions 0.5 to 2.5 GeV and 2.5 to 5.0 GeV. Measurement systematic errors due to neutrino flux, nuclear effects simulation, event reconstruction and detector response uncertainties has been evaluated.The result of the multi-pion relative cross section respect to quasielastic interactions measurement is 0.30 +- 0.07 (sta.) +- 0.15 (sys.) for neutrino energies between 0.5 and 2.5 GeV and 3.9 +- 0.6 (sta.) + 1.4 - 1.2 (sys.) for neutrino energies between 2.5 and 5.0 GeV.

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In this diploma thesis, we present a thorough investigation of the Vavilov-Cerenkov (VC) effect and its application to the detection of ultrahigh energyneutrinos. Neutrinos have no net charge and cannot emit VC radiation(VCR) but when they interact with a stationary medium such radiation isproduced by the Askar'yan effect. It has been proposed to use the lunarregolith as a detector material for such neutrino interactions, but in orderto do so, the VCR emitted from neutrino interactions has to be filtered outfrom that of other energetic particles impinging upon and penetrating intothe lunar surface. Since the principal difference between these emissions isdependent on the depth at which they occur, any boundary effects dependenton the distance from the point of emission to the surface is of interest.Therefore we examine the behavior of VCR near dielectric boundaries withextra care, both analytically and numerically. In order to keep the physicalpicture as clear as possible the analytical derivations are conducted in thetemporal domain. The boundary problem is studied both with respect tothe Maxwell boundary conditions and the method of images. In order toverify the analytic results and to make further investigations, a numericalMaxwell solver for the general VCR problem was constructed. The analyticand numeric results are then compared and proven to be equivalent. TheMaxwell solver is used to study the boundary problem and it is shown thatthe VCR emitted in a medium near the surface does not depend on the distanceto the surface in the same way as the opposite problem with a chargeabove the medium. In the case of a charge distribution traveling partiallyon both sides of the boundary some frequency dependent effects are shown.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 226-230). Available also in a digital version from Dissertation Abstracts.

MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. The neutrino beam is produced by the NuMI facility at Fermilab, Batavia, Illinois, and is observed at near and far detectors placed 734 km apart. The neutrino interactions in the near detector are used to measure the initial muon neutrino flux. The vast majority of neutrinos travel through the near detector and Earth matter without interactions. A fraction of muon neutrinos oscillate into other flavors resulting in the disappearance of muon neutrinos at the far detector. This thesis presents a measurement of the muon neutrino oscillation parameters in the framework of the two-neutrino oscillation hypothesis. / text

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In this thesis, the design of a high intensity accumulator ring for the European Spallation Source Neutrino Super Beam (ESSnuSB) is considered. The European Spallation Source (ESS) linear accelerator (Linac), presently being constructed in Lund, Sweden, presents an interesting opportunity to also host an experiment to detect neutrino CP violation. 0.7 ms long H- pulses would be accelerated to 2 GeV and collide with a target, producing pions which then decay into neutrinos. To focus the pions a toroidal magnet (''neutrino horn'') is pulsed with a 350 kA current. The peak current is about 5 μs long, which requires the H- pulses to be shortened to about the same length using an accumulator ring that is located between the linac and the target. The H- would be stripped of their electrons using either a thin carbon foil or a laser beam during injection into the ring. Foil stripping is limited by the lifetime of the foil, which depends on the temperature to which it is heated by the beam. The temperature is simulated in a computer model and the results indicate that it does not rise above the critical temperature (2500 K). The high number of protons (1015) circulating in the ring could cause instabilities due to the collective charge of the particles, known as the space charge effect. The space charge tune shift is calculated for the ESSnuSB and different solutions are discussed. The result of a design accumulator lattice for the ESSnuSB, based on the Spallation Neutron Source, at Oak Ridge National Laboratory, Tennessee, U.S., and made using the computer program Methodical Accelerator Design (MAD), is presented.

The Tokai-to-Kamioka (T2K) experiment is a long-baseline neutrino-oscillation experiment that searches for neutrino oscillations with measurements of an off-axis, high purity, muon neutrino beam. The neutrinos are detected 295 km from production by the Super Kamiokande detector. A near detector 280 m from the production target measures the unoscillated beam. This thesis outlines an analysis using samples in the near detector and Super Kamiokande to measure the disappearance of muon neutrinos. To manage the complexity this analysis, a Markov Chain Monte Carlo framework was used to maximize a likelihood to estimate the oscillation parameters. T2K Run 1+2+3 data (3.010 x10²⁰ POT) is used for the analysis. The estimates for the oscillation parameters are: ( sin² (2θ₂₃ ), Δ m²₃₂ ) = (0.999,2.45 x10ˉ³ [eV²]), and the 90% 1D bayesian credible intervals: 0.9340 < sin² (2θ₂₃ ) < 1.000 2.22 x10ˉ³ < Δm²₃₂ [eV²] < 2.74 x 10ˉ³ / Graduate / 0798