Dissertation

2018

#### Degree Name

Doctor of Philosophy

#### Department

Physics and Astronomy

#### Major

High Energy Physics

Mayly Sanchez

#### Abstract

NOvA is a long-baseline neutrino oscillation experiment that uses the NuMI beam from Fermilab.

Its physics goals include providing constraints to the neutrino mass hierarchy and the CP-violating phase $\delta$ by precision measurements of the electron (anti)neutrino

appearance in a muon (anti)neutrino beam.

Similarly, new limits on the values of $\sin^2{\theta_{23}}$ and $\Delta m^{2}_{32}$ will be achieved by measurements of the muon (anti)neutrino disappearance probabilities.

A combined analysis measurement will allow a better resolution of the $\theta_{23}$ octant.

The NuMI beam is produced by the collision of high energy protons into a target, giving rise to kaon and pion mesons that decay to neutrinos of a specific flavor.

This thesis presents a measurement of the kaon production normalization scale using uncontained charged-current muon neutrinos at the Far Detector.

Because the neutrino beam is not pure in flavor, it contains an admixture of other different neutrino flavors that become a source of background. %in oscillation analysis.

Therefore, it is of paramount importance for accelerator experiments, such as NOvA, to have a reliable flux prediction of the neutrino beam in order to achieve its physics goals.

One method to constrain the flux is to constrain and measure each flux component independently.

The kaon component contributes to the intrinsic $\nu_{e}$ contamination of the beam, a key background

for the $\nu_{e}$-appearance analysis.

We observed that the uncontained sample in the 10-20 GeV region corresponds to the kaon component of the NuMI beam at the Far Detector. We also found a 60-80\% correlation between the

Near Detector $\nu_{e}$ background and the Far Detector $\nu_{\mu}$ uncontained signal.

The data used for this analysis was collected from October 2014 to February 2017, corresponding to $7.99 \times 10^{20}$ protons-on-target (POT).

The ratio between the Far Detector data and the simulation is fitted to a line in the 10-20 GeV energy region.

Calibration, energy scale, final state interactions and neutrino flux (e.g. beam transport and hadron production shape only)

systematic uncertainties are considered. The kaon production normalization scale is measured to be $S_{K} = 1.07 \pm 0.16$.

Jose Andres Sepulveda-Quiroz

en

application/pdf

249 pages

COinS