# UCL Discovery

## Electron neutrino appearance in the MINOS experiment

Holin, A.M.; (2010) Electron neutrino appearance in the MINOS experiment. Doctoral thesis, UCL (University College London).

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## Abstract

The MINOS experiment is a long-baseline neutrino oscillation experiment which sends a high intensity muon neutrino beam through two functionally identical detectors, a Near detector at the Fermi National Accelerator Laboratory in Illinois, 1km from the beam source, and a Far detector, 734km away, in the Soudan Mine in Minnesota. MINOS may be able to measure the neutrino mixing angle parameter sin{^2}2\theta{_1_3} for the first time. Detector granularity, however, makes it very hard to distinguish any \nu{_e} appearance signal events characteristic of a non-zero value of \theta{_1_3} from background neutral current (NC) and short-track \nu{_\mu} charged current (CC) events. Also, uncertainties in the hadronic shower modeling in the kinematic region characteristic of this analysis are relatively large. A new data-driven background decomposition method designed to address those issues is developed and its results presented. By removing the long muon tracks from \nu{_\mu}-CC events, the Muon Removed Charge Current (MRCC) method creates independent pseudo-NC samples that can be used to correct the MINOS Monte Carlo to agree with the high-statistics Near detector data and to decompose the latter into components so as to predict the expected Far detector background. The MRCC method also provides an important cross-check in the Far detector to test the background in the signal selected region. MINOS finds a 1.0-1.5 \sigma\nu{_e}-CC excess above background in the Far detector data, depending on method used, for a total exposure of 3.14x10{^20} protons-on-target. Interpreting this excess as signal, MINOS can set limits on sin{^2}2\theta{_1_3}. Using the MRCC method, MINOS sets a limit of sin{^2}2\theta{_1_3} < 0:265 at the 90% confidence limit for a CP-violating phase \delta = 0.

Type: Thesis (Doctoral) Electron neutrino appearance in the MINOS experiment An open access version is available from UCL Discovery English The abstract contains LaTeX text. Please see the attached pdf for rendered equations UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Physics and Astronomy