Spin waves in the B-phase of superfluid ³He in confined cylindrical geometry

We describe experiments on superfluid ³He in a cylinder of 1 mm in diameter. This geometry causes the preferred orientation of the n-vector in the superfluid B-phase to be locally different, resulting in a curved configuration across the sample. Exclusive to our experiment is the observation that we succeeded in obtaining a texture which is metastable and unchanged in our pressure and temperature ranges, most likely because the experiment is performed at low pressures and low magnetic fields. As this texture can be considered as a potential for spin waves, we had the unique opportunity to study spin waves for several pressures in exactly the same texture. Our geometry causes this texture potential to be nearly quadratic, allowing an analytic solution of the theory which can be compared to our experimental results. As predicted we find the intensities of all spin wave modes more or less equal. Increasing the pressure shows a gradual increase in the number of spin wave modes in our cell. Finally we were able to cause a transition from the metastable to the predicted stable texture, concluding unexpectedly that the metastable texture is realized if the growing (or cooling) speed is sufficiently slow

Superfluid helium-3 in cylindrical restricted geometries : a study with low-frequency NMR

This thesis concerns the symmetry, phase, and order parameter of the superfluid helium-3 in restricted geometries in combination with a magnetic field. Two cylindrical containers are constructed for which the axis is aligned with the magnetic field. The first cell has a diameter (540 nm) of only a few times the size of the Cooper pairs, designed to find a new superfluid phase, namely the polar has. The second container has a diameter of 1 mm, which is the ideal size to create a potential (in the B-phase) for spin waves. To probe any superfluid phase, or spin waves, we use Nuclear Magnetic Resonance (NMR) Techniques. As the superfluids have an anisotropic susceptibility, it is an excellent tool to distinguish the different phases. However, as our samples are relatively small in volume, and the experiments needs to be performed in low magnetic field to prevent additional symmetry breaking, a very sensitive read-out magnetic resonance detection system needs to be developed, which is accomplish by creating an LC-circuit which maintains an ultra-high quality factor as it is combined with a weakly coupled transformer.LEI Universiteit LeidenCondensed Matter Condensed Physic

Vortex lattice dynamics in a-NbGe detected by mode-locking experiments

We observed mode-locking (ML) of rf-dc driven vortex arrays in a superconducting weak pinning a-NbGe film. The ML voltage shows the expected scaling $V\propto f\sqrt{B}$ with $f$ the rf-frequency and $B$ the magnetic field. For large dc-velocity (corresponding to a large ML frequency), the ML current step width exhibits a squared Bessel function dependence on the rf-amplitude as predicted for ML of a lattice moving elastically through a random potential.Comment: 2 pages, 2 figures. Contribution to M2S-HTSC Ri

A magnetic persistent current switch at milliKelvin temperatures

Quantum Matter and Optic

Microwave-assisted diastereoselective two-step three-component synthesis for rapid access to drug-like libraries of substituted 3-amino-beta-lactams

Chemical Immunolog

Piperidine and octahydropyrano[3,4-c] pyridine scaffolds for drug-like molecular libraries of the European Lead Factory

Molecular PhysiologyBio-organic Synthesi

Expansion of chemical space for collaborative lead generation and drug discovery: the European Lead Factory Perspective

High-throughput screening (HTS) represents a major cornerstone of drug discovery. The availability of an innovative, relevant and high-quality compound collection to be screened often dictates the final fate of a drug discovery campaign. Given that the chemical space to be sampled in research programs is practically infinite and sparsely populated, significant efforts and resources need to be invested in the generation and maintenance of a competitive compound collection. The European Lead Factory (ELF) project is addressing this challenge by leveraging the diverse experience and know-how of academic groups and small and medium enterprises (SMEs) engaged in synthetic and/or medicinal chemistry. Here, we describe the novelty, diversity, structural complexity, physicochemical characteristics and overall attractiveness of this first batch of ELF compounds for HTS purposes