Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Neuro-adaptive cooperative control for a class of high-order nonlinear multi-agent systems

In this paper, we studied the cooperative control problem for a class of high-order nonlinear multi-agent systems (MASs) with external disturbance and system uncertainty. A neuro-adaptive robust controller with sliding mode variable structure method, with an online-learning RBF-like neural network was proposed to approximate the nonlinear terms. Further, sliding mode variable structure method was used to eliminate the influence of external disturbance and system uncertainty. Lyapunov stability theorem verified the capability of system consensus, and the sufficient conditions for cooperatively uniformly ultimately bounded (CUUB) are also given. At last, two numerical simulations on both homogeneous and heterogeneous MASs demonstrated the effectiveness of our proposed method

Neuro-adaptive cooperative control for high-order nonlinear multi-agent systems with uncertainties

The consensus problem for a class of high-order nonlinear multi-agent systems (MASs) with external disturbance and system uncertainty is studied. We design an online-update radial basis function (RBF) neural network based distributed adaptive control protocol, where the sliding model control method is also applied to eliminate the influence of the external disturbance and system uncertainty. System consensus is verified by using the Lyapunov stability theorem, and sufficient conditions for cooperative uniform ultimately boundedness (CUUB) are also derived. Two simulation examples demonstrate the effectiveness of the proposed method for both homogeneous and heterogeneous MASs

Investigation of hydrogen adsorption sites in ferrocene-based hypercrosslinked polymers by DFT calculations

Herein, two types of Fc-based hypercrosslinked polymers (HHCP and DHCP) with high BET surface area (953.9 and 1062.7 m2 g−1) were prepared by direct one-step phenolic polycondensation aiming at high uptake capacity towards H2. As expected, the hydrogen uptake values of HHCP and DHCP were notably higher than those of porous polymers with a higher surface area under the same conditions. The maximum H2 uptake of HCPs at 77 K/1.0 bar are determined to be 2.51 wt % for HHCP and 2.74 wt % for DHCP, respectively. Despite the pore structure playing a determinant role in hydrogen adsorption, the adsorption sites in the polymer framework can be another essential factor to influence the hydrogen adsorption capacity. The interactions between the Fc building block and H2 are revealed by DFT calculation to fully illustrate the role of Fc in H2 adsorption. The results indicate that both iron atoms and benzene rings in Fc-based HCPs contribute to the adsorption of hydrogen. Moreover, it is interesting to find that the most stable adsorption site around the Fc building unit is the position directly above the Cp ring. The results in this work may more reasonably explain the phenomenon that the introduction of Fc units could enhance the adsorption of H2 in many studies, which also provides possible insights into the application of metallocene compounds in H2 adsorption

Export and remineralization of POM in the Southern Ocean and the South China Sea estimated from Po-210/Pb-210 disequilibria

Disequilibria between Po-210 and Pb-210 in the upper water and their potential applications as a proxy of particle export and remineralization were examined in the Southern Ocean (station IV3) and the South China Sea (NS44). Po-210 was deficit in surface waters but excessive relative to Pb-210 in subsurface waters. Good positive correlation between Po-210 and particulate organic carbon (POC) indicated deficits and excess of Po-210 resulted from particulate organic matter (POM) export and remineralization respectively, which was also supported by the decreased delta C-13 and increased delta N-15 downwards as a result of particle remineralization. On the basis of Po-210/Pb-210 box-model, POC export flux out of the surface waters were 1.2 mmol C center dot m(-2) center dot d(-1) and 2.3 mmol C center dot m(-2) center dot d(-1) for station NS44 and IV3, respectively. In the subsurface waters, remineralization fluxes of Po-210 were 0.062 Bq center dot m(-2) center dot d(-1) and 0.566 Bq center dot m(-2) center dot d(-1) for station NS44 and IV3 along with the recycle efficiency of 52 +/- 26% and 119 +/- 52%, respectively. Remineralized fluxes of POM derived from Po-210 and exported POC were 0.6 mmol C center dot m(-2) center dot d(-1) and 2.7 mmol C center dot m(-2) center dot d(-1) for NS44 and IV3. This study suggested that Po-210 was a powerful tracer of particle export and remineralization.National Natural Science Foundation of China [40576037, 90411016]; National Key Technology Research and Development Program [2006BAB19B03]; COMRA [DYXM-115-01-3-04