Muon Neutrino to Electron Neutrino Oscillation in NOnuA

NOvA is a long-baseline neutrino oscillation experiment optimized for electron neu- trino ( e) appearance in the NuMI beam, a muon neutrino ( $$\nu$$μ ) source at Fermilab. It consists of two functionally identical, nearly fully-active liquid-scintillator tracking calorimeters. The near detector (ND) at Fermilab is used to study the neutrino beam spectrum and composition before oscillation, and measure background rate to the $$\nu$$e appearance search. The far detector, 810 km away in Northern Minnesota, observes the oscillated beam and is used to extract oscillation parameters from the data. NO$$\nu$$ A's long baseline, combined with the ability of the NuMI beam to operate in the anti- neutrino mode, makes NO$$\nu$$ A sensitive to the last unmeasured parameters in neutrino oscillations- mass hierarchy, CP violation and the octant of mixing angle 23. This thesis presents the search for e appearance in the first data collected by the NO A detectors from October 2013 till May 2015. Studies of the NuMI neutrino data collected in the NO A near detector are also presented, which show large discrepancies between the ND simulation and data. Muon- removed electron (MRE) events, constructed by replacing the muon in $$\nu$$μ charged cur- rent interactions by a simulated electron, are used to correct the far detector $$\nu$$e appearance prediction for these discrepancies. In the analysis of the first data, a total of 6 e candidate events are observed in the far detector on a background of 1, a 3.46 σ excess, which is interpreted as strong evidence for e appearance. The results are consistent with our expectation, based on constraints from other neutrino oscillation experiments. The result presented here differs from the officially published $$\nu$$e appearance result from the NO A experiment where the systematic error is assumed to cover the MRE correction.

[1]  M. Ravonel.  Antineutrino oscillations with T2K , 2016 .

[2]  P. Mason,et al.  Liquid scintillator production for the NOvA experiment , 2015, 1504.04035.

[3]  M. Hartz,et al.  Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6E20 protons on target , 2015, 1502.01550.

[4]  C. Backhouse,et al.  Library Event Matching event classification algorithm for electron neutrino interactions in the NOνA detectors , 2015, 1501.00968.

[5]  D. L. Anderson.  Theory of Earth , 2014 .

[6]  R. Rechenmacher,et al.  Synchronization of the 14 kTon NOνA neutrino detector with the Fermilab NuMI beam , 2014 .

[7]  A. Aurisano,et al.  Combined analysis of νμ disappearance and νμ→νe appearance in MINOS using accelerator and atmospheric neutrinos. , 2014, Physical review letters.

[8]  I. G. Park,et al.  Observation of reactor electron antineutrinos disappearance in the RENO experiment. , 2012, Physical review letters.

[9]  S. Bilenky,et al.  Neutrinoless double-beta decay. A brief review , 2012, 1203.5250.

[10]  L. Y. Wang,et al.  Observation of electron-antineutrino disappearance at Daya Bay. , 2012, Physical review letters.

[11]  W. Hampel,et al.  Reanalysis of the GALLEX solar neutrino flux and source experiments , 2010, 1001.2731.

[12]  V. Tretyak,et al.  Semi-empirical calculation of quenching factors for ions in scintillators , 2009, 0911.3041.

[13]  R. Hatcher,et al.  The GENIE * Neutrino Monte Carlo Generator , 2009, 0905.2517.

[14]  T. J. Bowles,et al.  Measurement of the solar neutrino capture rate with gallium metal, part III , 2009 .

[15]  Manfred Lindner,et al.  The NOvA Technical Design Report , 2007 .

[16]  M. Chiarini,et al.  Complete results for five years of GNO solar neutrino observations , 2005, hep-ex/0504037.

[17]  M. Grassi,et al.  Search for neutrino oscillations on a long base-line at the CHOOZ nuclear power station , 2003, hep-ex/0301017.

[18]  Ritesh K. Singh,et al.  Research News : Direct observation of neutrino oscillations at the Sudbury Neutrino Observatory , 2002, physics/0208096.

[19]  M. B. Gavela,et al.  Golden measurements at a neutrino factory , 2000, hep-ph/0002108.

[20]  J. Bahcall,et al.  The Evolution of Neutrino Astronomy , 1999, astro-ph/9911486.

[21]  The Super-Kamiokande Collaboration,et al.  Evidence for oscillation of atmospheric neutrinos , 1998, hep-ex/9807003.

[22]  R. Cousins,et al.  A Unified Approach to the Classical Statistical Analysis of Small Signals , 1997, physics/9711021.

[23]  M. Pinsonneault,et al.  ARE STANDARD SOLAR MODELS RELIABLE , 1996, astro-ph/9610250.

[24]  Hans-Peter Kriegel,et al.  A Density-Based Algorithm for Discovering Clusters in Large Spatial Databases with Noise , 1996, KDD.

[25]  M. Ohlsson.  Extensions and explorations of the elastic arms algorithm , 1993 .

[26]  James M. Keller,et al.  A possibilistic approach to clustering , 1993, IEEE Trans. Fuzzy Syst..

[27]  P. H. Heckmann.  Search for neutrinos from the Sun , 1973 .

[28]  J. B. Birks,et al.  The Theory and Practice of Scintillation Counting , 1965 .

[29]  C. Chou.  The Nature of the Saturation Effect of Fluorescent Scintillators , 1952 .

[30]  Kuo-Lung Wu,et al.  Unsupervised possibilistic clustering , 2006, Pattern Recognit..

[31]  R. E. Kalman,et al.  A New Approach to Linear Filtering and Prediction Problems , 2002 .

[32]  R. Blin-stoyle.  Elementary particles and their interactions , 1991 .

[33]  J. Dunn.  A Fuzzy Relative of the ISODATA Process and Its Use in Detecting Compact Well-Separated Clusters , 1973 .