Feasibility investigation of direct laser cutting process of metal foam with high pore density

To avoid damage to the pore structure of metal foam, a laser cutting process for efficiently and directly cutting metal foam into regular shapes is proposed. After analyzing the proposed laser cutting process, its effects when applied to three different types of metal material (copper, ferroalloy, and nickel) and two levels of pore density, namely 90 and 110 pores per inch (PPI), were investigated. The results show that metal foam with a good surface quality can be obtained without damaging the pore structure by using the proposed laser cutting process. Of the three metal types considered, the highest material removal rate (MRR) and material oxidation rate (MOR) were observed for ferroalloy foam. Of the two pore densities, metal foam of 90 PPI showed a larger material removal rate than metal foam of 110 PPI. The MRR and MOR increased with an increase in the laser output power and decrease in the scanning speed. Using a central composite experimental design method, optimized processing parameters of 26 W laser output power and 475 mm/s scanning speed were adopted to cut the metal foam with a high pore density

Detecting Neutrinos from Supernova Bursts in PandaX-4T

Neutrinos from core-collapse supernovae are essential for the understanding of neutrino physics and stellar evolution. The dual-phase xenon dark matter detectors can provide a way to track explosions of galactic supernovae by detecting neutrinos through coherent elastic neutrino-nucleus scatterings. In this study, a variation of progenitor masses as well as explosion models are assumed to predict the neutrino fluxes and spectra, which result in the number of expected neutrino events ranging from 6.6 to 13.7 at a distance of 10 kpc over a 10-second duration with negligible backgrounds at PandaX-4T. Two specialized triggering alarms for monitoring supernova burst neutrinos are built. The efficiency of detecting supernova explosions at various distances in the Milky Way is estimated. These alarms will be implemented in the real-time supernova monitoring system at PandaX-4T in the near future, providing the astronomical communities with supernova early warnings.Comment: 9 pages,6 figure