5,250 research outputs found
Thermal issues at the SSC
A variety of heat transfer problems arise in the design of the Superconducting Super Collider (SSC). One class of problems is to minimize heat leak from the ambient to the SSC rings, since the rings contain superconducting magnets maintained at a temperature of 4 K. Another arises from the need to dump the beam of protrons (traveling around the SSC rings) on to absorbers during an abort of the collider. Yet another category of problems is the cooling of equipment to dissipate the heat generated during operation. An overview of these problems and sample heat transfer results are given in this paper
Thermodynamically stable noncomposite vortices in mesoscopic two-gap superconductors
In mesoscopic two-gap superconductors with sizes of the order of the
coherence length noncomposite vortices are found to be thermodynamically stable
in a large domain of the phase diagram. In these phases the vortex
cores of one condensate are spatially separated from the other condensate ones,
and their respective distributions can adopt distinct symmetries. The
appearance of these vortex phases is caused by a non-negligible effect of the
boundary of the sample on the superconducting order parameter and represents
therefore a genuine mesoscopic effect. For low values of interband Josephson
coupling vortex patterns with can arise in addition to the
phases with , where and are total vorticities in the two
condensates. The calculations show that noncomposite vortices could be observed
in thin mesoscopic samples of MgB.Comment: 5 pages, 3 figures, to be published in Europhysics Letter
Study of intermixing in a GaAs/AlGaAs quantum-well structure using doped spin-on silica layers
The effect of two different dopants, P and Ga, in spin-on glass (SOG) films on impurity-free vacancy disordering (IFVD) in GaAs/AlGaAs quantum-well structures has been investigated. It is observed that by varying the annealing and baking temperatures, P-doped SOG films created a similar amount of intermixing as the undoped SOG films. This is different from the results of other studies of P-doped SiO₂ and is ascribed to the low doping concentration of P, indicating that the doping concentration of P in the SiO₂ layer is one of the key parameters that may control intermixing. On the other hand, for all the samples encapsulated with Ga-doped SOG layers, significant suppression of the intermixing was observed, making them very promising candidates with which to achieve the selective-area defect engineering that is required for any successful application of IFVD.One of the authors (H.H.T.) acknowledges a fellowship
awarded to him by the Australian Research Council
Scanning SQUID microscopy of vortex clusters in multiband superconductors
In type-1.5 superconductors, vortices emerge in clusters, which grow in size
with increasing magnetic field. These novel vortex clusters and their field
dependence are directly visualized by scanning SQUID microscopy at very low
vortex densities in MgB2 single crystals. Our observations are elucidated by
simulations based on a two-gap Ginzburg-Landau theory in the type-1.5 regime.Comment: 4 pages, 5 figures, to be published in Physical Review
A Benchmarking Study of Matching Algorithms for Knowledge Graph Entity Alignment
How to identify those equivalent entities between knowledge graphs (KGs),
which is called Entity Alignment (EA), is a long-standing challenge. So far,
many methods have been proposed, with recent focus on leveraging Deep Learning
to solve this problem. However, we observe that most of the efforts has been
paid to having better representation of entities, rather than improving entity
matching from the learned representations. In fact, how to efficiently infer
the entity pairs from this similarity matrix, which is essentially a matching
problem, has been largely ignored by the community. Motivated by this
observation, we conduct an in-depth analysis on existing algorithms that are
particularly designed for solving this matching problem, and propose a novel
matching method, named Bidirectional Matching (BMat). Our extensive
experimental results on public datasets indicate that there is currently no
single silver bullet solution for EA. In other words, different classes of
entity similarity estimation may require different matching algorithms to reach
the best EA results for each class. We finally conclude that using PARIS, the
state-of-the-art EA approach, with BMat gives the best combination in terms of
EA performance and the algorithm's time and space complexity.Comment: 11 pages, 1 figure, 7 table
Alpha-nucleus potential for alpha-decay and sub-barrier fusion
The set of parameters for alpha-nucleus potential is derived by using the
data for both the alpha-decay half-lives and the fusion cross-sections around
the barrier for reactions alpha+40Ca, alpha+59Co, alpha+208Pb. The alpha-decay
half-lives are obtained in the framework of a cluster model using the WKB
approximation. The evaluated alpha-decay half-lives and the fusion
cross-sections agreed well with the data. Fusion reactions between
alpha-particle and heavy nuclei can be used for both the formation of very
heavy nuclei and spectroscopic studies of the formed compound nuclei.Comment: 10 pages, 5 figure
Ultrafast trapping times in ion implanted InP
As⁺ and P⁺implantation was performed on semi-insulating (SI) and p-type InP samples for the purpose of creating a material suitable for ultrafast optoelectronic applications. SI InP samples were implanted with a dose of 1×10¹⁶ cm⁻² and p-type InP was implanted with doses between 1×10¹² and 1×10¹⁶ cm⁻². Subsequently, rapid thermal annealing at temperatures between 400 and 700 °C was performed for 30 sec. Hall-effect measurements, double-crystal x-ray diffraction, and time-resolved femtosecond differential reflectivity showed that, for the highest-annealing temperatures, the implanted SI InP samples exhibited high mobility, low resistivity, short response times, and minimal structural damage. Similar measurements on implantedp-type InP showed that the fast response time, high mobility, and good structural recovery could be retained while increasing the resistivity
- …