We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis sp...
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We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observation period covered by this analysis spans from October 13, 2015, to April 30, 2022 (2392 days). The very wide dynamic range of CALET allowed for the collection of helium data over a large energy interval, from ∼40 GeV to ∼250 TeV, for the first time with a single instrument in low Earth orbit. The measured spectrum shows evidence of a deviation of the flux from a single power law by more than 8σ with a progressive spectral hardening from a few hundred GeV to a few tens of TeV. This result is consistent with the data reported by space instruments including PAMELA, AMS-02, and DAMPE and balloon instruments including CREAM. At higher energy we report the onset of a softening of the helium spectrum around 30 TeV (total kinetic energy). Though affected by large uncertainties in the highest energy bins, the observation of a flux reduction turns out to be consistent with the most recent results of DAMPE. A double broken power law is found to fit simultaneously both spectral features: the hardening (at lower energy) and the softening (at higher energy). A measurement of the proton to helium flux ratio in the energy range from 60 GeV/n to about 60 TeV/n is also presented, using the CALET proton flux recently updated with higher statistics.
We present a straightforward method to fabricate free‐standing Ni(OH) 2 /NiOOH nanostructures by etching three‐dimensional nickel foam (NF) in HCl or H 2 SO 4 . Acid corrosion liberates Ni 2+ ions that interact with...
We present a straightforward method to fabricate free‐standing Ni(OH) 2 /NiOOH nanostructures by etching three‐dimensional nickel foam (NF) in HCl or H 2 SO 4 . Acid corrosion liberates Ni 2+ ions that interact with Cl − or SO 4 2− to form Ni hydroxide and oxyhydroxide phases directly on the NF substrate. The resulting hierarchical porous network uniformly embeds Ni(OH) 2 and NiOOH throughout the conductive foam, providing abundant active sites for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) intermediates. This architecture enhances specific surface area, ionic mobility, electrical conductivity, and charge transfer efficiency, leading to superior catalytic performance. In alkaline water electrolysis, the Ni(OH) 2 /NiOOH electrode achieves 20 mA cm −2 at only 1.61 V in a two‐electrode setup and remains stable for over 12 h. It also demonstrates exceptional corrosion resistance in unpurified seawater compared to bare Ni and bimetallic NF. Comprehensive characterizations and electrochemical analyses confirm that the modulated surface structure, robust catalyst‐support interactions, and enhanced mass transport yield a highly efficient, durable, and cost‐effective bifunctional electrocatalyst. Our synthesis is scalable and environmentally benign for sustainable energy.
The inclusive jet cross section is measured as a function of jet transverse momentum pT and rapidity y. The measurement is performed using proton-proton collision data at s = 5.02 TeV, recorded by the CMS experiment a...
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Accessibility to participation in the high energy physics community can be impeded by many barriers. These barriers must be acknowledged and addressed to make access more equitable in the future. An accessibility surv...
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The undulator line of the Shanghai soft X-ray Free-electron Laser facility (SXFEL) has very tight tolerances on the straightness of the electron beam trajectory. However, the beam trajectory cannot meet the lasing req...
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The ATLAS experiment at the Large Hadron Collider has a broad physicsprogramme ranging from precision measurements to direct searches for new particles and new interactions, requiring ever larger and ever more accura...
Computing demands for large scientific experiments, such as the CMS experiment at the CERN LHC, will increase dramatically in the next decades. To complement the future performance increases of software running on cen...
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PbTe crystals have a soft transverse optical phonon mode in the terahertz frequency range, which is known to efficiently decay into heat-carrying acoustic phonons, resulting in anomalously low thermal conductivity. He...
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PbTe crystals have a soft transverse optical phonon mode in the terahertz frequency range, which is known to efficiently decay into heat-carrying acoustic phonons, resulting in anomalously low thermal conductivity. Here, we studied this phonon via polarization-dependent terahertz spectroscopy. We observed softening of this mode with decreasing temperature, indicative of incipient ferroelectricity, which we explain through a model including strong anharmonicity with a quartic displacement term. In magnetic fields up to 25 T, the phonon mode splits into two modes with opposite handedness, exhibiting circular dichroism. Their frequencies display Zeeman splitting together with an overall diamagnetic shift with increasing magnetic field. Using a group-theoretical approach, we demonstrate that these observations are the result of magnetic field-induced morphic changes in the crystal symmetries through the Lorentz force exerted on the lattice ions. Thus, our Letter reveals a novel process of controlling phonon properties in a soft ionic lattice by a strong magnetic field.
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