of neutron capture on gadolinium (nGd). Since the delayed signal of 2.2 MeV falls into the energy region totally dominated by natural radiation, the coincidence background is huge. By requiring the reconstructed distance between the positron and delayed-neutron vertices be $<50$ cm, 98% of this background can be rejected while losing 25% of the signal. A spectral subtraction is further needed to remove the accidental backgrounds. An analysis using the 217-day data set yielded $\sin^22\theta_{13}=0.080\pm0.018$. Since the IBD sample and the systematic uncertainties are largely independent from the nGd analysis, the nH analysis provides an independent measurement of $\theta_{13}$. The correlation between the nH and nGd analyses is evaluated to be 0.05. When the nH and nGd analyses of this data set are combined, the $\sin^22\theta_{13}$ sensitivity is improved by 8% [@DB_nH].

Reactor Antineutrino Spectrum and Exotic searches {#reactor}
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Although the oscillation analyses of Daya Bay have negligible dependence on the external prediction of the reactor antineutrino flux and spectrum, the knowledge is a crucial factor for many reactor experiments. In early studies, the estimation relied on calculations or other indirect means, such as the $\beta$ spectrum measurements made on reactor fuels, based on the understanding of the complex 