Data Science

On the 5th of May the two beam stoppers were installed in the SwissFEL tunnel. These two blocks are made out of copper, recycled lead, steel and concrete blocks and weight 60 tons each. These stoppers are placed in front of both Aramis and Athos undulator lines.

We report a new limit on a possible short range spin-dependent interaction from the precise measurement of the ratio of Larmor precession frequencies of stored ultracold neutrons and ¹⁹⁹Hg atoms confined in the same volume. The measurement was performed in a ∼1μT vertical magnetic holding field with the apparatus searching for a permanent electric dipole moment of the neutron at the Paul Scherrer Institute.

Materials with broad absorption bands are highly desirable for electromagnetic filtering and processing applications, especially if the absorption can be externally controlled. Here, a new class of broadband-absorption materials is introduced. Namely, layered metamagnets exhibit an electromagnetic excitation continuum in the magnetic-field-induced mixed ferro- and antiferromagnetic phase.

The standard model of particle physics describes the fundamental particles and their interactions via the strong, electromagnetic and weak forces. It provides precise predictions for measurable quantities that can be tested experimentally. The probabilities, or branching fractions, of the strange B meson (B_S⁰) and the B₀ meson decaying into two oppositely charged muons (μ⁺ and μ^-) are especially inter- esting because of their sensitivity to theories that extend the standard model. The standard model predicts that the B_S⁰ →μ⁺μ^- and B⁰ →μ⁺μ^- decays are very rare, with about four of the former occurring for every billion Bs0 mesons produced, and one of the latter occurring for every ten billion B⁰ mesons.

High-resolution neutron imaging (Neutron Microscope project) requires highly efficient scintillator screens. Our aim is to achieve sub-5µm spatial resolution. Here, we demonstrate the feasibility of the production of isotopically-enriched gadolinium oxysulfide scintillator screens for the high spatial-resolution neutron imaging. Approximately 10 g of ¹⁵⁷Gd₂O₂S:Tb was produced in the form of fine powder (the level of ¹⁵⁷Gd enrichment above 88%).

High-resolution neutron imaging (Neutron Microscope project) requires highly efficient scintillator screens. Our aim is to achieve sub-5µm spatial resolution. Here, we demonstrate the feasibility of the production of isotopically-enriched gadolinium oxysulfide scintillator screens for the high spatial-resolution neutron imaging. Approximately 10 g of ¹⁵⁷Gd₂O₂S:Tb was produced in the form of fine powder (the level of ¹⁵⁷Gd enrichment above 88%).

We use nuclear magnetic resonance (NMR), high-resolution x-ray, and neutron scattering studies to study structural and magnetic phase transitions in phosphorus-doped BaFe₂(As_1-xP_x)₂. Previous transport, NMR, specific heat, and magnetic penetration depth measurements have provided compelling evidence for the presence of a quantum critical point (QCP) near optimal superconductivity at x=0.3.

The detailed understanding of particle motion in the outer region (halo) of a bunched beam is of utmost importance for all existing and future high intensity hadron accelerators in view of minimizing particle losses and machine activation. Particle-core models separate the motion of halo particles from the core and treat them as test-particles. Therefore these reduced-order models are computationally inexpensive compared to full particle-in-cell simulations and can, to some extent, be derived analytically, thus giving insights into the non-linear mechanism of halo formation.

One of the technological barriers to electrification of transport is the insufficient storage capacity of the Li-ion batteries on which the current electric cars are based. The lithium-sulfur (Li-S) battery is an advanced technology whose successful commercialization can lead to significant gains in the storage capacity of batteries and promote wide-spread adoption of electric vehicles.

Researchers at PSI have developed a technique that combines tomography measurements at different resolution levels to allow quantitative interpretation for nanoscale tomography on an interior region of interest of the sample. In collaboration with researchers of the institute AMOLF in the Netherlands and ETH Zurich in Switzerland they showcase their technique by studying the porous structure within a section of an avian eggshell. The detailed measurements of the interior of the sample allowed the researchers to quantify the ordering and distribution of an intricate network of pores within the shell.

Calcium silicate hydrates (C-S-H) are the most abundant hydration products in ordinary Portland cement paste. Yet, despite the critical role they play in determining mechanical and transport properties, there is still a debate about their density and exact composition. Here, the site-specific mass density and composition of C-S-H in hydrated cement paste are determined with nanoscale resolution in a nondestructive approach.

Inhomogeneity in the ground state is an intriguing, emergent phenomenon in magnetism. Recently, it has been observed in the magnetostructural channel of the geometrically frustrated α-NaMnO₂, for the first time in the absence of active charge degrees of freedom. Here we report an in-depth numerical and local-probe experimental study of the isostructural sister compound CuMnO₂ that emphasizes and provides an explanation for the crucial differences between the two systems.

Table-top soft x-ray lasers based on high-order harmonic generation (HHG) deliver routinely linearly polarized light. Many advanced applications including magnetic imaging would profit from a HHG source delivering in addition circular polarized light. In one of our recent work we present now an approach which provides intense soft x-ray radiation of high ellipticity. This source has given us the opportunity to realize the first magnetic dichroism experiment on a nickel sample at 18 nm (67 eV) with a table-top HHG source.

A total of 104 C-band accelerating structures will be needed for SwissFEL. Each of these structures is about 2 m long and consists out of 113 copper cells that are manufactured with micrometer precision using ultra-precision diamond machining, which results in mirror-like surfaces. The main components are the couplers at the input and the output of the structure, and the copper disks. For both, couplers and disks, the series production was successfully launched at the end of 2014. Since then the Dutch company VDL and TEL Mechatronics in Trübbach, Switzerland, delivered already many sets of couplers and accelerating disks, respectively.

Diamagnetic oxides can, under certain conditions, become ferromagnetic at room temperature and therefore are promising candidates for future material in spintronic devices. Contrary to early predictions, doping ZnO with uniformly distributed magnetic ions is not essential to obtain ferromagnetic samples. Instead, the nanostructure seems to play the key role, as room temperature ferromagnetism was also found in nanograined, undoped ZnO.

A quantum critical point (QCP) occurs upon chemical doping of the weak itinerant ferromagnet Sc_3.1In. Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity.

The interaction between the endohedral unit in the single-molecule magnet Dy₂ScN@C₈₀ and a rhodium (111) substrate leads to alignment of the Dy 4f orbitals. The resulting orientation of the Dy₂ScN plane parallel to the surface is inferred from comparison of the angular anisotropy of x-ray absorption spectra and multiplet calculations in the corresponding ligand field.

For many years, PSI researchers have been testing experimental methods that will provide insights into novel materials for electronic devices. Using a special trick to make the Swiss Light Source (SLS) at PSI generate light with similar properties to that of PSI's x-ray laser SwissFEL, the researchers were able to demonstrate that the experiments planned for SwissFEL are possible and they are now building an experimental station at SwissFEL. read the full story)

Hydrogen in the Earth's deep interior has been thought to exist as a hydroxyl group in high-pressure minerals. We present Muon Spin Rotation experiments on SiO₂ stishovite, which is an archetypal high-pressure mineral. Positive muon (which can be considered as a light isotope of proton) implanted in stishovite was found to capture electron to form muonium (corresponding to neutral hydrogen).

Inhomogeneity in the ground state is an intriguing, emergent phenomenon in magnetism. Recently, it has been observed in the magnetostructural channel of the geometrically frustrated α-NaMnO₂, for the first time in the absence of active charge degrees of freedom. Here we report an in-depth numerical and local-probe experimental study of the isostructural sister compound CuMnO₂ that emphasizes and provides an explanation for the crucial differences between the two systems.