Title: Constraints on neutrino oscillation parameters with the NOvA experiment

Abstract

NOvA is a long-baseline neutrino oscillation experiment, which consists of two finely-segmented liquid-scintillator detectors operating 14 mrad off-axis from the NuMI muon neutrino beam. With an 810 km baseline, the combined measurements of muon neutrino disappearance and electron neutrino appearance allow the determination of neutrino oscillation unknowns, namely the mass hierarchy, the octant of the largest neutrino mixing angle, and the CP violating phase. In this dissertation I present the joint analysis of $$\nu_\mu \to \nu_\mu$$ and $$\nu_\mu \to \nu_e$$ oscillation data with an exposure of $$8.85\times10^{20}$$ protons on target on the 14 kton detector. It includes the estimation of neutrino energy distributions in the far detector using near detector data constraints, details of the implementation of the simultaneous fit of \numu and \nue samples, and the effect of systematic uncertainties on the measurement of oscillation parameters. I also discuss NOvA's projected sensiti vity to determine the mass hierarchy and discover CP violation in future analyses with increased exposure and the addition of antineutrino datasets. With 66 electron neutrino and 126 muon neutrino candidates, the best fit to the data corresponds to the normal mass hierarchy, $$\Delta m^2_{32}=2.44\times 10^{-3} eV^2/c^4$$, $$\sin^2 \theta_{23}=0.56$$, and $$\delta_{CP} = 1.21\pi$$, with the allowed regionsmore » $$\Delta m^2_{32} \in [2.37,2.52]\times 10^{-3} eV^2/c^4$$, $$\sin^2 \theta_{23} \in [0.43,0.51] \cup [0.52,0.60]$$ and $$\delta_{CP} \in [0,0.12\pi] \cup [0.91\pi,2\pi]$$ at the 68.3\% C.L. Our data disfavor maximal mixing by 0.8$$\sigma$$, $$\delta_{CP} = \pi/2$$ in the inverted hierarchy at higher than 3$$\sigma$$, and the entire inverted mass hierarchy at the 95\% confidence level. % By increasing the size of the samples and adding anti-neutrino data, \nova can potentially resolve the neutrino mass hierarchy at 4$$\sigma$$ C.L. or higher for some combinations of oscillation parameters. Im provements to the sensitivity to the determination of the ma! ss hierarchy and CP violation in the neutrino sector can be achieved through gains in the NuMI beam intensity, the inclusion of external data, and refinements in the analysis methodology.« less

Authors:

Catano Mur, Erika ^[1]

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1. Iowa State U.

Publication Date:

2018-01-01

Research Org.:

Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

OSTI Identifier:

1498546

Report Number(s):

FERMILAB-THESIS-2018-29
1724268

DOE Contract Number:  

AC02-07CH11359

Resource Type:

Thesis/Dissertation

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS