The Daya Bay Reactor Neutrino Experiment

The Daya Bay reactor neutrino experiment is a high sensitivity experiment designed to determine the last unknown neutrino mixing angle $theta13$ by measuring disappearance of reactor antineutrinos emitted from six 2.9 $GWth$ reactors at the Daya Bay Nuclear Power Station. There are eight identical Gd-loaded liquid scintillator detectors deployed in two near (flux-weighted baseline 512 $m$ and 561 $m$) and one far (1579 $m$) underground experimental halls to detect the inverse beta decay interaction. This dissertation describes the Daya Bay Experiment and individual contributions to this experiment.

Chapter 1 reviews the history of the neutrino and the neutrino oscillation phenomena. The reactor based neutrino experiments in different times are described in this chapter in detail. It presents the motivation of the Daya Bay Experiment. In Chapter 2, the neutrino detection method and the $theta13$ relative measurement method are introduced. This chapter focuses on the design of the Daya Bay Experiment, including antineutrino detector, calibration system, muon veto system and muon tagging system. Chapter 3 shows the design, development, construction, and assembly of Muon Pool PMT calibration system, and presents an algorithm of calculating the muon pool PMT timing offset values. Chapter 4 focuses on the manufacture, installation and commissioning of RPC HV system. Chapter 5 presents the analyses of the radioactive isotopes induced by comic muons. The Daya Bay detector energy response model is also described in detail.

The relative rate analysis results exclude a zero value from $sin22theta13$ with a significance of 7.7 standard deviation using 139 days of data, 28909 (205308) antineutrino candidates which were recorded at the far hall (near halls) and shows $sin22theta13=0.089pm0.011$ in a three-neutrino framework. A combined analysis of the $overlinenue$ rates and energy spectra based on the detector energy response model improved measurement of the mixing angle $sin22theta13=0.090-0.009+0.008$ by using 217 days of data, 41589 (203809 and 92912) antineutrino candidates were detected in the far hall (near halls). Also the first direct measurement of the $overlinenue$ mass-squared difference $|Deltamee2|=(2.59-0.20+0.19)times10-3$ $eV2$. It is consistent with $|Deltammumu2|$ measured by muon neutrino disappearance, supporting the three-flavor oscillation model.