In reactor neutrino experiments, the analysis of time correlations between different physical events is an important task. Such analysis can help to understand the physical mechanisms of the signal and background events as well as the details of event selection and background estimation. This study investigates a ＂sampling and mixing＂ method used for producing large MC data samples for the Daya Bay reactor neutrino experiment. We designed a simple, generic mixing algorithm and generated large MC data samples for physics analysis from several samples according to their respective event rates. Basic plots based on the mixed data are shown.
In this paper, we first discuss the detection of supernova neutrinos on earth. Then we propose a possible method to acquire information about θ13 smaller than 1.5° by detecting the ratio of the event numbers of different flavor supernova neutrinos. Such an sensitivity cannot yet be achieved by the Daya Bay reactor neutrino experiment.
Owing to its low cost and good transparency,highly purified water is widely used as a medium in large water Cerenkov detector experiments. The water circulation and purification system is usually needed to keep the water in good quality. In this work,a practical circulation model is built to describe the variation of the water resistivity in the circulation process and compared with the data obtained from a prototype experiment. The successful test of the model makes it useful in the future design and optimization of the circulation/purification system.
Detailed measurements of Hamamatsu R5912 photomultiplier signals are presented, including the single photoelectron charge response, waveform shape, nonlinearity, saturation, overshoot, oscillation, prepulsing, and afterpulsing. The results were used to build a detailed model of the PMT signal characteristics over a wide range of light intensities. Including the PMT model in simulated Daya Bay particle interactions shows no significant systematic effects that are detrimental to the experimental sensitivity.
Reactor neutrino oscillation experiments, such as Daya Bay, Double Chooz and RENO are designed to determine the neutrino mixing angle θ13 with a sensitivity of 0.01--0.03 in sin^2 2θ13 at 90% confidence level, an improvement over the current limit by more than one order of magnitude. The control of systematic uncertainties is critical to achieving the sin^22θ13 sensitivity goal of these experiments. Antineutrinos emitted from spent nuclear fuel （SNF） would distort the soft part of energy spectrum and may introduce a non-negligible systematic uncertainty. In this article, a detailed calculation of SNF neutrinos is performed taking account of the operation＂ of a typical reactor and the event rate in the detector is obtained. A further estimation shows that the event rate contribution of SNF neutrinos is less than 0.2% relative to the reactor neutrino signals. A global X2 analysis shows that this uncertainty will degrade the θ13 sensitivity at a negligible level.
