We investigate the magneto-transport properties of epitaxial graphene single-layer on 4H-SiC(0001), grown by atmospheric pressure graphitization in Ar, followed by H2 intercalation. We directly ...demonstrate the importance of saturating the Si dangling bonds at the graphene/SiC(0001) interface to achieve high carrier mobility. Upon successful Si dangling bonds elimination, carrier mobility increases from 3 000 cm(2)V(-1)s(-1) to >11 000 cm(2)V(-1)s(-1) at 0.3 K. Additionally, graphene electron concentration tends to decrease from a few 10(12) cm(-2) to less than 10(12) cm(-2). For a typical large (30 × 280 μm(2)) Hall bar, we report the observation of the integer quantum Hall states at 0.3 K with well developed transversal resistance plateaus at Landau level filling factors of ν = 2, 6, 10, 14... 42 and Shubnikov de Haas oscillation of the longitudinal resistivity observed from about 1 T. In such a device, the Hall state quantization at ν = 2, at 19 T and 0.3 K, can be very robust: the dissipation in electronic transport can stay very low, with the longitudinal resistivity lower than 5 mΩ, for measurement currents as high as 250 μA. This is very promising in the view of an application in metrology.
The numerical simulation of complex, nonlinear and coupled, electromagnetic and thermal dynamics involved in the quench phenomena of magnesium diboride (MgB 2 ) superconducting magnets requires a ...suitable modeling of the interaction among the different aspects. As a matter of fact, magnets wound using MgB 2 tapes are characterized by material parameters and working temperatures leading to different behaviors with respect to either low T c superconductors (LTS) and high T c (HTS) superconductors, and thus requiring special care in the modeling of quench diffusion phenomena. In this paper, a 3-D finite-element method (FEM) model able to cope with such phenomena is presented and model predictions are compared to experimental data.
b-jet triggering in ATLAS Cavaliere, Viviana
Journal of physics. Conference series,
01/2012, Letnik:
396, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The online event selection is crucial to reject most of the events containing uninteresting background collisions while preserving as much as possible the interesting physics signals. The b-jet ...selection is part of the trigger strategy of the ATLAS experiment and a set of dedicated triggers is in place from the beginning of the 2011 data-taking period and is contributing to keep the total bandwidth to an acceptable rate. These triggers are used in many physics analyses, especially those with topologies containing more than one b-jet where higher rejection factors are achieved that benefit from requesting this trigger to be fired. An overview of the b-jet trigger menu and the performance on data is presented in this contribution.
The bulk superconductors can be used as permanent magnets of very high magnetic induction, provided that a feasible way of magnetization is identified and that the superconducting material can ...withstand the magnetic forces induced by high trapped abstract truncated by publisher.
In order to investigate the quench behavior of conduction cooled MgB(2) magnets, a 100 mm inner bore diameter, 0.84 T at 20 K magnet has been built and tested. The test magnet consists of 4 double ...pancakes wound with the MgB(2)/Ni abstract truncated by publisher.
Three-dimensional quench propagation in HTS coils Cavaliere, V.; Cioffi, M.; Formisano, A. ...
IEEE transactions on magnetics,
04/2006, Letnik:
42, Številka:
4
Journal Article, Conference Proceeding
The behavior of high temperature superconductor (HTS) coils is ruled by thermal and electromagnetic interacting phenomena. In this paper, a three-dimensional modeling of the quench propagation in HTS ...coils is discussed and numerically modeled. As a matter of fact, in spite of the axially symmetric design, a simple two-dimensional modelization may reveal too rough, particularly from the thermal point of view. In addition, the possibility of representing the complex structure of the coil composite material by means of a simplified homogeneous and anisotropic model is discussed and the advantages in terms of computational burden are evaluated
The bulk superconductors can be used as permanent magnets of very high magnetic induction, provided that a feasible way of magnetization is identified and that the superconducting material can ...withstand the magnetic forces induced by high trapped fields. Here it has been considered as superconducting permanent magnet a bulk MgB 2 ring, obtained by the Reactive Liquid Infiltration (RLI) process. This material offers several advantages with respect to the well known YBCO textured material, even if its application temperature will be far lower, around 20-30 K. First of all, MgB 2 does not require grain orientation to reach enough current density, it can be produced in a quite straight forward way, it is lightweight and it is mechanically robust. To magnetize the MgB 2 ring, we have applied a DC magnetic field with a superconducting magnet, using a step wise, field cooling type, procedure. The induced magnetization of the bulk MgB 2 ring, at 4 K, is around 2 T in its vicinity. It has been verified that the magnetization is very stable during the time and it can withstand also AC disturbances of several Hz in frequency.
In order to investigate the quench behavior of conduction cooled MgB 2 magnets, a 100 mm inner bore diameter, 0.84 T at 20 K magnet has been built and tested. The test magnet consists of 4 double ...pancakes wound with the MgB 2 /Ni -Cu-Fe tape produced by Columbus. Each coil is cooled by means of a 2 mm thick copper disk placed during winding at the middle of the double pancake; after winding the double pancakes have been separately epoxy impregnated. Several experiments have been performed inducing a local transition in the coil by means of a controlled heater placed on the double pancake surface. The propagation of the normal zone has been monitored by means of 8 voltage probes positioned along the tape during coil manufacturing. Each voltage probe detects the voltage drop across a tape length of 30 mm. The experiments have been performed at different temperatures while keeping the magnet current constant during quench. In the paper we report an analysis of the quench propagation velocity measurements and a numerical investigation of the thermal and electrical behavior of the magnet.
A study was made of the localization and assembly of the VM32E protein, a putative vitelline membrane component of the Drosophila eggshell. The results highlight some unique features of this protein ...compared with the other proteins of the same gene family. At the time of its synthesis (stage 10), the VM32E protein is not detectable in polar follicle cells. However, it is able to move in the extracellular space around the oocyte and, by stage 11 is uniformly distributed in the vitelline membrane. During the terminal stages of oogenesis the VM32E protein is partially released from the vitelline membrane and becomes localized in the endochorion layer also. By analyzing transgenic flies carrying variously truncated VM32E proteins, we could identify the protein domains required for the proper assembly of the VM32E protein in the eggshell. The highly conserved vitelline membrane domain is implicated in the early interactions with other components and is required for cross-linking VM32E protein in the vitelline membrane. The terminal carboxylic domain is necessary for localization to the endochorion layer. Protein with the C-end domain deleted is localized solely to the vitelline membrane and cross-linked only in laid eggs, as occurs for the other vitelline membrane proteins.
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