Controlled Manipulation of Individual Vortices in a Superconductor

We report controlled local manipulation of single vortices by low temperature magnetic force microscope (MFM) in a thin film of superconducting Nb. We are able to position the vortices in arbitrary configurations and to measure the distribution of local depinning forces. This technique opens up new possibilities for the characterization and use of vortices in superconductors

Metal-coated carbon nanotube tips for Magnetic Force Microscopy

We fabricated cantilevers for magnetic force microscopy with carbon nanotube tips coated with magnetic material. Images of a custom hard drive demonstrated 20 nm lateral resolution, with prospects for further improvements.Comment: Accepted to be published in Applied Physics Letter

Strategie ter beheersing van citruswolluis in de potplantenteelt : onderzoek 2003

In 2002 is door PPO Glastuinbouw een methode ontwikkeld om een aantasting van het gewas door citruswolluis aan te kunnen tonen. Hierbij werd gebruik gemaakt van feromoonvallen. Onduidelijk is nog hoe de feromoonval precies in de praktijk gebruikt kan worden. Dit verslag rapporteert over onderzoek naar het gebruik van feromoonvallen in de praktijk. Het doel van het onderzoek was het onderzoeken van de mogelijkheid van het gebruik van feromoonvallen voor het plannen van de biologische en chemische bestrijding van de citruswolluis (Planococcus citri), en het vaststellen van de relatie tussen de vangst in de feromoonval en de wolluispopulatie in gewas

Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor

Superconductors often contain quantized microscopic whirlpools of electrons, called vortices, that can be modelled as one-dimensional elastic objects1. Vortices are a diverse area of study for condensed matter because of the interplay between thermal fluctuations, vortex–vortex interactions and the interaction of the vortex core with the three-dimensional disorder landscape. Although vortex matter has been studied extensively, the static and dynamic properties of an individual vortex have not. Here, we use magnetic force microscopy (MFM) to image and manipulate individual vortices in a detwinned YBa2Cu3O6.991 single crystal, directly measuring the interaction of a moving vortex with the local disorder potential. We find an unexpected and marked enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning.Physic

Beam Test of Silicon Strip Sensors for the ZEUS Micro Vertex Detector

For the HERA upgrade, the ZEUS experiment has designed and installed a high precision Micro Vertex Detector (MVD) using single sided micro-strip sensors with capacitive charge division. The sensors have a readout pitch of 120 microns, with five intermediate strips (20 micron strip pitch). An extensive test program has been carried out at the DESY-II testbeam facility. In this paper we describe the setup developed to test the ZEUS MVD sensors and the results obtained on both irradiated and non-irradiated single sided micro-strip detectors with rectangular and trapezoidal geometries. The performances of the sensors coupled to the readout electronics (HELIX chip, version 2.2) have been studied in detail, achieving a good description by a Monte Carlo simulation. Measurements of the position resolution as a function of the angle of incidence are presented, focusing in particular on the comparison between standard and newly developed reconstruction algorithms.Comment: 41 pages, 21 figures, 2 tables, accepted for publication in NIM