MiniBooNE oscillation searches Page: 1 of 6
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MiniBooNE Oscillation Searches
Fermilab, Neutrino Department, Mail Station 309, Batavia, IL 60510-500, USA
Abstract. The range of oscillation analyses being pursued by the MiniBooNE collaboration
is described. Focus is given to the various searches for electron neutrino appearance, but the
disappearance of muon neutrinos and the appearance search for electron anti-neutrinos are
covered as well.
The Mini-Booster Neutrino Experiment (MiniBooNE) was built to probe the oscillation
interpretation of the LSND result . It uses 8 GeV protons from the Fermilab Booster to
produce a high purity beam of ~- 0.7 GeV v by running the protons into a Be target followed
by a focusing horn. The detector is located 541m from the target and comprises a spherical
tank of inner radius 610 cm filled with 800 tons of pure mineral oil (CH2). The oil is viewed by
1280 inch PMTs and surrounded by a veto region viewed by 280 PMTs. Using the pattern and
timing of the Cerenkov and scintillation light hitting the tubes the experiment can distinguish
electrons from other particles (in particular ps and Ars) and so test for v -> ve oscillations.
2. Electron Neutrino Appearance
2.1. Oscillation Result
In April 2007 the experiment released it's first results . The experiment found no evidence
of neutrino oscillations in its analysis region above a neutrino energy of 475 MeV, though there
was a excess of events found below this energy and this is currently under investigation. The
exclusion plot that results from this measurement is shown in Fig. 1 along with the expected
and measured reconstructed neutrino energy spectrum of the electron neutrino candidates.
2.2. 7r Rate Measurement
A vital component of the ve appearance analysis that is not often highlighted is the analysis
of Neutral Current (NC) 7r events in the detector. By using a detailed two Cerenkov ring
reconstruction and a simple set of cuts MiniBooNE is able to identify a high purity sample of
NC Ar events spanning the full range of Ar kinematics. The reconstructed mass distribution of
this sample is shown on the left in Fig. 2 and the clear peak at the Ar mass indicates the high
purity of the sample. On the right of Fig. 2 is shown the expected (red) and measured (blue) A
momentum distribution. The ratio of these two distributions as a function of Ar momentum is
used as a reweighting function to correct the predicted Ar rate to that observed in the detector.
This correction is vital to the ve appearance analysis as NC Ar events misidentified as ve events
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Brice, Stephen J. MiniBooNE oscillation searches, article, January 1, 2008; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc898300/m1/1/: accessed July 18, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.