Performance of compact plastic scintillator strips with WLS-fiber and PMT/SiPM readout

This work presents the design and performance study of compact strips of plastic scintillator with WLS-fiber readout in a dimension of 0.1 * 0.02 * 2 m3, which evaluates as a candidate for cosmic-ray muon detector for JUNO-TAO. The strips coupling with 3-inch PMTs are measured and compared between the single-end and double-end readout options first, and the strip of double-end option coupling with SiPM is further measured and compared with the results of that with the PMTs. The performance of the strips determined by a detailed survey along their length with cosmic-ray muon after a detailed characterization of the used 3-inch PMTs and SiPMs.The proposed compact strip of plastic scintillator with WLS-fiber coupling with SiPM provides a good choice for cosmic-ray muon veto detector for limited detector dimension in particular

Template synthesis of palladium nanotubes and their electrocatalytic properties

Palladium nanotubes were prepared by using silver nanowires as the template, which were prepared in a modified polyol reduction process. The morphology and structure of silver nanowires and palladium nanotubes were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrochemical experimental data showed that palladium nanotubes displayed high electrocatalytic activity toward the electrooxidation of alcohols, especially for ethanol. The formation mechanism of palladium nanotubes as well as the relationship between their structure and electrocatalytic activity was discussed based on the experimental results

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

Template synthesis and electrocatalytic properties of palladium hollow spheres

Palladium hollow spheres were synthesized at room temperature using cobalt nanoparticles (NPs) as sacrificing templates. Cobalt NPs can be prepared simply by solvothermal method. The hollow nature of sample Pd were observed from the TEM image and the SAED pattern indicates the polycrystalline nature of the sample. It was found that Pd hollow spheres showed high catalytic activity towards the electrooxidation of alcohols, especially ethanol with the current density up to 2047 mA mg-1. The formation mechanism and the structure-property relationship of Pd hollow spheres were discussed based on the experimental results

Preparation and characterization of nanostructured Pd with high electrocatalytic activity

Two kinds of Pd nanoparticle aggregates with different electrocatalytic activity are developed in a facile hydrothermal synthesis method. The average size of Pd nanoparticles synthesized from the mixed solvent containing water and acetone (Pd–M) is ∼9 nm smaller than that of Pd samples synthesized from aqueous systems (Pd–A) with the size of ∼14 nm. Nanoparticles of Pd–M and Pd–A show the crystalline nature based on the XRD and HRTEM results. It is found that Pd–M display a remarkably high electrooxidation activity per unit mass toward formic acid and ethanol, which is 8–12 times as high as that of Pd–A. The electrooxidation activity per unit area of Pd–M is also higher than that of Pd–A. The formation mechanisms of Pd–A and Pd–M as well as the relationship between their microstructures and electrocatalytic activity have been discussed based on the experimental result