Tests of a Novel Design of Resistive Plate Chambers

A novel design of Resistive Plate Chambers (RPCs), using only a single resistive plate, is being proposed. Based on this design, two large size prototype chambers were constructed and were tested with cosmic rays and in particle beams. The tests confirmed the viability of this new approach. In addition to showing an improved single-particle response compared to the traditional 2-plate design, the novel chambers also prove to be suitable for calorimetric applications

Metal-organic-frameworks derived cobalt embedded in various carbon structures as bifunctional electrocatalysts for oxygen reduction and evolution reactions

This is the final version of the article. Available from Springer Nature via the DOI in this record.A series of nanocomposites of cobalt embedded in N-doped nanoporous carbons, carbon nanotubes or hollow carbon onions have been synthesized by a one-step carbonization of metal-organic-framework ZIF-67. The effect of the carbonization temperature on the structural evolution of the resulting nanocomposites has been investigated in detail. Among the as-synthesized materials, the cobalt/nanoporous N-doped carbon composites have demonstrated excellent electrocatalytic activities and durability towards oxygen reduction reaction in alkaline medium. Compared to the benchmark Pt/C catalyst, the optimized Co@C-800 (carbonized at 800 °C) exhibited high oxygen reduction reaction activity with an onset potential of 0.92 V, and a half-wave potential of 0.82 V. Moreover, the optimized Co@C-800 also showed enhanced electrocatalytic activity towards oxygen evolution reaction from water splitting, with a low onset potential of 1.43 V and a potential of 1.61 V at 10 mA cm−2 current density. This work offered a simple solution to develop metal-organic-framework-derived materials for highly efficient electrochemical applications.The financial support by the EPSRC (EP/N034627/1), Royal Society and University of Exeter is greatly acknowledged

Momentum Distribution of Near-Zero-Energy Photoelectrons in the Strong-Field Tunneling Ionization in the Long Wavelength Limit

We investigate the ionization dynamics of Argon atoms irradiated by an ultrashort intense laser of a wavelength up to 3100 nm, addressing the momentum distribution of the photoelectrons with near-zero-energy. We find a surprising accumulation in the momentum distribution corresponding to meV energy and a \textquotedblleft V"-like structure at the slightly larger transverse momenta. Semiclassical simulations indicate the crucial role of the Coulomb attraction between the escaping electron and the remaining ion at extremely large distance. Tracing back classical trajectories, we find the tunneling electrons born in a certain window of the field phase and transverse velocity are responsible for the striking accumulation. Our theoretical results are consistent with recent meV-resolved high-precision measurements.Comment: 5 pages, 4 figure

Large exchange bias after zero-field cooling from an unmagnetized state

Exchange bias (EB) is usually observed in systems with interface between different magnetic phases after field cooling. Here we report an unusual phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after zero-field cooling from an unmagnetized state. We propose this is related to the newly formed interface between different magnetic phases during the initial magnetization process. The magnetic unidirectional anisotropy, which is the origin of EB effect, can be created isothermally below the blocking temperature.Comment: including supplementary information, Accepted by Physical Review Letter

Analytic Spectra of CMB Anisotropies and Polarization Generated by Relic Gravitational Waves with Modification due to Neutrino Free-Streaming

We present an analytical calculation of the spectra of CMB anisotropies and polarizations generated by relic gravitational waves (RGWs). As a substantial extension to the previous studies, three new ingredients are included in this work. Firstly, the analytic $C_l^{TT}$ and $C_l^{TE}$ are given; especially the latter can be useful to extract signal of RGWs from the observed data in the zero multipole method. Secondly, a fitting formula of the decaying factor on small scales is given, coming from the visibility function around the photon decoupling. Thirdly, the impacts by the neutrino free-streaming (NFS) is examined, a process that occurred in the early universe and leaves observable imprints on CMB via RGWs. It is found that the analytic $C_l^{TT}$ and $C_l^{TE}$ have profiles agreeing with the numeric ones, except that $C^{TT}_l$ in a range $l \le 10$ and the $1^{st}$ trough of $C_l^{TE}$ around $l \sim 75$ have some deviations. With the new damping factor, the analytic $C^{EE}_l$ and $C^{BB}_l$ match with the numeric ones with the maximum errors only $\sim 3$ up to the first three peaks for $l\le 600$, improving the previous studies substantially. The correspondence of the positions of peaks of $C^{XX}_l$ and those of RGWs are also demonstrated explicitly. We also find that NFS reduces the amplitudes of $C^{XX}_l$ by $(20$ for $l\simeq(100\sim 600)$ and shifts slightly their peaks to smaller angles. Detailed analyses show that the zero multipoles $l_0$, where $C_l^{TE}$ crosses 0, are shifted to larger values by NFS. This shifting effect is as important as those causedby different inflation models and different baryon fractions.Comment: 17 pages, 7 figures. accepted by PR

Measurements of the Rate Capability of Various Resistive Plate Chambers

Resistive Plate Chambers (RPCs) exhibit a significant loss of efficiency for the detection of particles, when subjected to high particle fluxes. This rate limitation is related to the usually high resistivity of the resistive plates used in their construction. This paper reports on measurements of the performance of three different glass RPC designs featuring a different total resistance of the resistive plates. The measurements were performed with 120 GeV protons at varying beam intensitie

Improved Hydrogen Release from Ammonia Borane Confined in Microporous Carbon with Narrow Pore Size Distribution

This is the author accepted manuscript. The final version is available from Royal Society of Chemistry via the DOI in this record.Ammonia borane is a promising hydrogen storage candidate due to its high hydrogen capacity and good stability at room temperature, but there are still some barriers to be overcome before it can be used for practical applications. We present the hydrogen release from ammonia borane confined in templated microporous carbon with extremely narrow pore size distribution. Compared with neat ammonia borane, hydrogen release temperature of ammonia borane confined in microporous carbon with pore size of 1.05 nm is significantly reduced, starting at 50 C and with peak dehydrogenation temperature centred at 86 C. The dehydrogenation kinetics of ammonia borane confined in templated microporous carbon is significantly improved and by-products including ammonia and diborane are also completely prohibited without any catalysts involved. The remarkable fast hydrogen release rate and high hydrogen storage capacity from ammonia borane confined in microporous carbon is due to the dramatic decrease in the activation energy of ammonia borane. This is so far the best performance among porous carbon materials used as the confinement scaffolds for ammonia borane in hydrogen storage, making AB confined in microporous carbon a very promising candidate for hydrogen storage.The financial support by the Royal Society and University of Exeter is greatly acknowledged

Interference Cancellation at Receivers in Cache-Enabled Wireless Networks

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