Estudo da oscilação de neutrinos muônicos usando dados atmosféricos e de acelerador nos experimentos MINOS e MINOS+
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2015-05-07
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Universidade Federal de Goiás
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The MINOS (Main Injector Neutrino Oscillation Search) and MINOS+ experiments were designed
to study neutrino oscillations using a muon neutrino beam which is detected in two
different locations, in the Near Detector and in the Far Detector. The distance between the
detectors allows the beam neutrinos to oscillate to a different flavor. Therefore, a disappearance
of the muon neutrinos from the beam is observed in the Far Detector. The Far Detector has a
special apparatus which makes possible the selection of atmospheric neutrinos and antineutrinos.
These come from interactions of cosmic rays with the Earth’s atmosphere. Both detectors
have a magnetic field, allowing the distiction between neutrinos and antineutrinos interactions.
This thesis presents the first combined analysis of data from the MINOS and MINOS+
experiments. We have analyzed the combined neutrino energy spectrum from the complete
MINOS beam data and the first, more energetic, MINOS+ beam data. The disappearance of
the muon neutrinos was observed and the data has shown to be congruent with the oscillation
model. Beyond that, we have measured the atmospheric oscillation parameters of the beam
and atmospheric neutrinos and antineutrinos from MINOS combined with the atmospheric neutrinos
and antineutrinos from MINOS+. Assuming the same oscillation parameters for both
neutrinos and antineutrinos, the best fit is obtained for inverted hierarchy and lower octant
with m2
32 = 2:37 103 eV2 and sin2 23 = 0:43, and the limits m2
32 = [2,29 - 2,49] 103
eV2 (68%) and sin2 23 = 0.36 - 0.66 (90%). These results are the most precise measurement of
the neutrinos mass splitting using muon neutrino disappearance data only.
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MEDEIROS, M. M. Estudo da oscilação de neutrinos muônicos usando dados atmosféricos e de acelerador nos experimentos MINOS e MINOS+. 2015. 215 f. Tese (Doutorado em Fisica) - Universidade Federal de Goiás, Goiânia, 2015.