Precise measurement of mixing parameters and sterile neutrino search at Daya Bay

Neutrino oscillation with three active neutrinos has been well established by experiments. However, θ_13 was the least known mixing angle before the Daya Bay reactor neutrino experiment. The Daya Bay experiment uses relative measurement with eight identically-designed antineutrino detectors (ADs) located in two near sites, each with two ADs, and one far site with four ADs. In 2012, Daya Bay first observed the non-zero value of (sin^2)2θ_13 at a > 5σ significance with the initial six ADs. In the summer of 2012, the last two ADs were installed to complete the full configuration. In this thesis, the data set of 217 days of 6-AD data and 404 days of 8-AD data were analyzed. The reactor electron antineutrinos ν_e were observed via the inverse beta decay reaction, v_e + p → (e^+) + n. The v_e events were selected by the delayed coincidence between the (e^+) signal and the neutron capture occurring on average 30 μs later. The data quality was carefully checked. A (Χ^2) analysis was constructed with nuisance parameters to consider the detector-related and the background uncertainties and a covariance matrix to encapsulate the reactor uncertainties. This analysis found (sin^2)θ2_13 =0.083 ± 0.0047 and Δ[(m^2)_32] = (2.43 ± 0.10) x (10^-3) e(V^2), assuming normal mass hierarchy. Furthermore, a search for the sterile neutrinos, neutrinos that do not interact weakly with matter, was conducted. A combined analysis with the Bugey and MINOS experiments was performed, and the result was directly compared with the allowed regions set by the LSND and MiniBooNE experiments.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2016

Author dc:creator

• Huang, En-Chuan

Contributors dc:contributor

• Peng, Jen-Chieh
• Yang, Liang
• Fields, Brian D.
• Errede, Steven M.

• Daya Bay
• neutrino oscillation
• theta13

Statement dc:rights

• Copyright 2016 En-Chuan Huang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/92705

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/92705