Paul Scherrer Institute

About: Paul Scherrer Institute is a facility organization based out in Villigen, Switzerland. It is known for research contribution in the topics: Neutron & Large Hadron Collider. The organization has 9248 authors who have published 23984 publications receiving 890129 citations. The organization is also known as: PSI.

The new μE4 beam at PSI: A hybrid-type large acceptance channel for the generation of a high intensity surface-muon beam

Abstract: At the Paul Scherrer Institute (PSI, Villigen, Switzerland) the existing μ E 4 decay muon channel has been replaced by a hybrid-type beam line consisting of two normal-conducting solenoids with rotational symmetry close to the muon production target E, followed by a conventional beam line composed of large aperture bending and quadrupole magnets with midplane symmetry. The new μ E 4 beam line with a design momentum of 28 MeV / c has been planned to deliver highest surface- μ + flux onto the 3 × 3 -cm 2 moderator target of the low-energy, polarized μ + source ( LE- μ + ) to generate an intense LE- μ + beam with tunable energy between 1 and 30 keV for muon spin rotation ( μ SR ) applications on thin films, multi-layers and near surface regions (depths ≲ 300 nm ). The main objective was the increase of solid-angle acceptance by about one order of magnitude taking into account stringent space limitations given by the geometry of the muon production target and the existing main shielding of the proton channel. Two normal-conducting solenoids as first focusing elements allow achieving this goal. With a solid-angle acceptance of Δ Ω ∼ 135 msr the new μ E 4 delivers currently the surface- μ + beam with highest flux of 4.2 × 10 8 μ + / s at a proton current of 2 mA, 4-cm long graphite production target E. About 40% of the beam can be focused onto the LE- μ + moderator target to generate LE- μ + with a rate up to 16 × 10 3 / s .

Direct observation of thermal relaxation in artificial spin ice.

Abstract: We study the thermal relaxation of artificial spin ice with photoemission electron microscopy, and are able to directly observe how such a system finds its way from an energetically excited state to the ground state. On plotting vertex-type populations as a function of time, we can characterize the relaxation, which occurs in two stages, namely a string and a domain regime. Kinetic Monte Carlo simulations agree well with the temporal evolution of the magnetic state when including disorder, and the experimental results can be explained by considering the effective interaction energy associated with the separation of pairs of vertex excitations.

Stable complete methane oxidation over palladium based zeolite catalysts.

Abstract: Increasing the use of natural gas engines is an important step to reduce the carbon footprint of mobility and power generation sectors. To avoid emissions of unburnt methane and the associated severe greenhouse effect of lean-burn engines, the stability of methane oxidation catalysts against steam-induced sintering at low temperatures (<500 °C) needs to be improved. Here we demonstrate how the combination of catalyst development and improved process control yields a highly efficient solution for complete methane oxidation. We design a material based on palladium and hierarchical zeolite with fully sodium-exchanged acid sites, which improves the support stability and prevents steam-induced palladium sintering under reaction conditions by confining the metal within the zeolite. Repeated short reducing pulses enable the use of a highly active transient state of the catalyst, which in combination with its high stability provides excellent performance without deactivation for over 90 h in the presence of steam.

X-ray diffraction observations of a charge-density-wave order in superconducting ortho-II YBa2Cu3O6.54 single crystals in zero magnetic field.

Abstract: X-ray diffraction measurements show that the high-temperature superconductor YBa2Cu3O6.54, with ortho-II oxygen order, has charge-density-wave order in the absence of an applied magnetic field. The dominant wave vector of the charge density wave is q(CDW) = (0, 0.328(2), 0.5), with the in-plane component parallel to the b axis (chain direction). It has a similar incommensurability to that observed in ortho-VIII and ortho-III samples, which have different dopings and oxygen orderings. Our results for ortho-II contrast with recent high-field NMR measurements, which suggest a commensurate wave vector along the a axis. We discuss the relationship between spin and charge correlations in YBa2Cu3Oy and recent high-field quantum oscillation, NMR, and ultrasound experiments. DOI: 10.1103/PhysRevLett.110.137004