Mostrando 1 - 13 Resultados de 13 Para Buscar 'SOLANO-SALINAS, C.J.', tiempo de consulta: 0.05s Limitar resultados
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EL ESTUDIO TIENE COMO OBJETIVO EVALUAR LA DOSIS ABSORBIDA (DABS) EN TRATAMIENTOS DE BRAQUITERAPIA POR ALTA TASA DE DOSIS CON UNA FUENTE DE 192IR, CONSIDERANDO LAS HETEROGENEIDADES DE LOS TEJIDOS, TIPOS DE APLICADORES Y DIMENSIONES DEL PACIENTE. PARA ESTE FIN, SE REALIZARON CÁLCULOS DE ISODOSIS POR SIMULACIÓN MONTECARLO (MC) Y UNA PRUEBA DE EXACTITUD DE LA DOSIS ENTREGADA A UN OBJETO SIMULADOR, COMPARANDO LA DABS PLANIFICADA EN EL SISTEMA DE PLANIFICACIÓN DE TRATAMIENTO (TPS) CON LA DOSIS REGISTRADA POR EL DOSÍMETRO DE LUMINISCENCIA ÓPTICAMENTE ESTIMULADA. SE OBTUVO QUE EL TPS CALCULA ADECUADAMENTE LA DISTRIBUCIÓN DE DABS, CUANDO EL MEDIO ES AGUA; SIN EMBARGO, ES NECESARIO INCLUIR LAS LIBRERÍAS QUE CONSIDERAN LAS HETEROGENEIDADES PARA REALIZAR CON MAYOR PRECISIÓN EL CÁLCULO DE LA DISTRIBUCIÓN DE DABS EN LOS PACIENTES. SE CONCLUYÓ QUE AL REALIZAR UNA SIMULACIÓN MC ES UNA BUENA ...
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Neutrino interaction events in the MINERνA detector are visually represented with a web-based tool called Arachne. Data are retrieved from a central server via AJAX, and client-side JavaScript draws images into the users browser window using the draft HTML 5 "standard". These technologies allow neutrino interactions to be viewed by anyone with a web browser, allowing for easy hand-scanning of particle interactions. Arachne has been used in MINERνA to evaluate neutrino data in a prototype detector, to tune reconstruction algorithms, and for public outreach and education. © 2012 Published by Elsevier B.V.
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Charged-current νμ interactions on carbon, iron, and lead with a final state hadronic system of one or more protons with zero mesons are used to investigate the influence of the nuclear environment on quasielasticlike interactions. The transferred four-momentum squared to the target nucleus, Q2, is reconstructed based on the kinematics of the leading proton, and differential cross sections versus Q2 and the cross-section ratios of iron, lead, and carbon to scintillator are measured for the first time in a single experiment. The measurements show a dependence on the atomic number. While the quasielasticlike scattering on carbon is compatible with predictions, the trends exhibited by scattering on iron and lead favor a prediction with intranuclear rescattering of hadrons accounted for by a conventional particle cascade treatment. These measurements help discriminate between different mod...
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The semiexclusive channel νμ þ CH → μ−π0 þ nucleonðsÞ is analyzed using MINERvA exposed to the low-energy NuMI νμ beam with spectral peak at Eν ≃ 3 GeV. Differential cross sections for muon momentum and production angle, π0 kinetic energy and production angle, and for squared four-momentum transfer are reported, and the cross section σðEνÞ is obtained over the range 1.5 GeV ≤ Eν < 20 GeV. Results are compared to GENIE and NuWro predictions and to published MINERvA cross sections for charged-current πþðπ0Þ production by νμðν¯μÞ neutrinos. Disagreements between data and simulation are observed at very low and relatively high values for muon angle and for Q2 that may reflect shortfalls in modeling of interactions on carbon. For π0 kinematic distributions, however, the data are consistent with the simulation and provide support for generator treatments o...
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The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an in situ prediction of the shape of the flux as a function of neutrino energy from 2–50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy (ν) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-ν flux technique, the first time it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeVenergies. The cross section measurements presented are the most precise mea...
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Neutrino induced coherent charged pion production on nuclei, ν¯μA → μ π∓A, is a rare inelastic interaction in which the four-momentum squared transferred to the nucleus is nearly zero, leaving it intact. We identify such events in the scintillator of MINERvA by reconstructing jtj from the final state pion and muon momenta and by removing events with evidence of energetic nuclear recoil or production of other final state particles. We measure the total neutrino and antineutrino cross sections as a function of neutrino energy between 2 and 20 GeV and measure flux integrated differential cross sections as a function of Q2, Eπ, and θπ. The Q2 dependence and equality of the neutrino and antineutrino cross sections at finite Q2 provide a confirmation of Adler’s partial conservation of axial current hypothesis.
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Muon-neutrino elastic scattering on electrons is an observable neutrino process whose cross section is precisely known. Consequently a measurement of this process in an accelerator-based νμ beam can improve the knowledge of the absolute neutrino flux impinging upon the detector; typically this knowledge is limited to ∼10% due to uncertainties in hadron production and focusing. We have isolated a sample of 135±17 neutrino-electron elastic scattering candidates in the segmented scintillator detector of MINERvA, after subtracting backgrounds and correcting for efficiency. We show how this sample can be used to reduce the total uncertainty on the NuMI νμ flux from 9% to 6%. Our measurement provides a flux constraint that is useful to other experiments using the NuMI beam, and this technique is applicable to future neutrino beams operating at multi-GeV energies. © 2016 American Physic...
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Single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) is studied using the MINERvA detector exposed to the NuMI low-energy, wideband antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for appearance oscillation experiments. The differential cross sections for momentum and production angle, for events with a single observed and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the kinematics for this process.
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MINERvA presents a new analysis of neutrino induced quasielastic-like interactions in a hydrocarbon tracking target. We report a double-differential cross section using the muon transverse and longitudinal momentum. In addition, differential cross sections as a function of the square of the four-momentum transferred and the neutrino energy are calculated using a quasielastic hypothesis. Finally, an analysis of energy deposited near the interaction vertex is presented. These results are compared to modified genie predictions as well as a NuWro prediction. All results use a data set produced by 3.34×1020 protons on target creating a neutrino beam with a peak energy of approximately 3.5 GeV. .
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We present measurements of the neutrino and antineutrino total charged-current cross sections on carbon and their ratio using the MINERvA scintillator-tracker. The measurements span the energy range 2–22 GeV and were performed using forward and reversed horn focusing modes of the Fermilab low-energy NuMI beam to obtain large neutrino and antineutrino samples. The flux is obtained using a subsample of charged-current events at low hadronic energy transfer along with precise higher energy external neutrino cross section data overlapping with our energy range between 12–22 GeV.We also report onthe antineutrino-neutrino cross section ratio, RCC, which does not rely on external normalization information. Our ratio measurement, obtained within the same experiment using the same technique, benefits from the cancellation of common sample systematic uncertainties and reaches a precision of ...
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The MINERvA experiment observes an excess of events containing electromagnetic showers relative to the expectation from Monte Carlo simulations in neutral-current neutrino interactions with mean beam energy of 4.5 GeV on a hydrocarbon target. The excess is characterized and found to be consistent with neutral-current π0 production with a broad energy distribution peaking at 7 GeV and a total cross section of 0.26 0.02ðstat.Þ 0.08ðsys:Þ × 10−39 cm2. The angular distribution, electromagnetic shower energy, and spatial distribution of the energy depositions of the excess are consistent with expectations from neutrino neutral-current diffractive π0 production from hydrogen in the hydrocarbon target. These data comprise the first direct experimental observation and constraint for a reaction that poses an important background process in neutrino-oscillation experiments searching for ...
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The MINERvA collaboration operated a scaled-down replica of thesolid scintillator tracking and sampling calorimeter regions of the MINERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This paper reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons is obtained from these data. A measurement of the parameter in Birks' law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4% for the calorimetric response, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINE...
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The skin is the largest organ of the body that protects it from the external environment. High- frequency ultra sound (HF-US) has been used to visualize the skin in depth and to diagnose some pathologies in dermatological applications. Quantitative ultrasound (QUS) includes several techniques that provide values of particular physical properties. In this thesis work, three QUS parameters are explained and used to characterize healthy skin through HF-US: attenuation coefficient slope (ACS), backscatter coefficient (BSC) and shear wave speed (SWS). They were estimated with the regularized spectral-log difference (RSLD) method, the reference phan- tom method, and the crawling wave sonoelastography method, respectively. All the three parameters were assessed in phantoms, ex vivo and in vivo skin. In calibrated phantoms, RSLD showed a reduc- tion of up to 93% of the standard deviation concern...