Recherche sur le Covid-19

In nuclear safety analyses, the assessment of hydrogen release, distribution, and mitigation in the containment has high relevance, because under certain postulated scenarios, combustible mixture could form and hydrogen explosions could damage safety systems.

Safety analyses is carried out using advanced computational tools that have been assessed and validated through a variety of the analyses based experiments representative of the phenomena postulated in the containment and obtained in highly instrumented thermal-hydraulics facilities.

The OECD/NEA HYMERES project (www.psi.ch/en/teg/projects) was carried out to create an experimental database consisting in 24 PANDA tests and 9 MISTRA (CEA, France) tests devoted to phenomena with high relevance in nuclear safety. In two PANDA tests identified as HP6_1 and HP6_2) was investigated the effect of complex natural circulation in a PWR two-room type containment, on the hydrogen distribution, during postulated accidents [1]. The PANDA test specifications have been determined based on scoping analyses with the GOTHIC and APROS advanced computational tools [2].

Researchers in a joint collaboration between the PolLux endstation of the Swiss Light Source and the University of Leeds have achieved the reliable and reproducible electrical nucleation of magnetic skyrmions from a nano-engineered point contact structure, investigating the physical mechanisms driving the nucleation process.

Nuclear reactors are complex systems with inherent stochastic behaviour. In simple words, the behaviour of various reactor processes are continuously fluctuating over their mean values, even under normal operation and steady-state conditions. The detailed and systematic analysis of this noisy behaviour can reveal valuable information about the operating status of the studied nuclear reactor. More importantly, designed modifications of the reactor’s operation or even unexpected deviations from the normal performance can be identified using advanced signal analysis techniques. The STARS program, at the Laboratory for Reactor Physics and Thermal-Hydraulics (LRT) in PSI, based on a tight collaboration with the Swiss nuclear industry, has developed a well-established signal analysis methodology, being continuously improved since more than two decades. The latest enhancements of the PSI signal analysis methodology allow a deeper understanding of the underlying mechanisms that drive the reactor’s operation, and can provide better insight on the root-cause of possible disturbances or malfunctions. Recently, the latest STARS activities in advanced signal analysis techniques were culminated by an international recognition through a special distinction from the AIP Chaos Journal.

Phonon engineering of solids enables the creation of materials with tailored heat-transfer properties, controlled elastic and acoustic vibration propagation, and custom phonon-electron and phonon-photon interactions. These can be leveraged for energy transport, harvesting, or isolation applications and in the creation of novel phonon-based devices, including photoacoustic systems and phonon-communication networks.

A new 6M€ grant is being launched for the Photon and Neutron Data Services (ExPaNDS) to come together and work under the European Open Science Cloud (EOSC). This ambitious project will create enormous opportunities for scientific communities, and through their findings for humankind worldwide. It aims to publish and map the data behind the thousands of successful published scientific papers generated by Europe’s Photon and Neutron Research Infrastructures (PaN RIs) – which every year create petabytes of data – and make it available to all.

Recently, the transition metal dichalcogenide (TMD) system 2M-WS₂ has been identified as a Dirac semimetal exhibiting both superconductivity with the highest T_c ~ 8.5 K among all the TMD materials and topological surface states. Here we report on muon spin rotation (μSR) and density functional theory studies of microscopic SC properties and the electronic structure in 2M-WS₂ at ambient and under hydrostatic pressures (p_max = 1.9 GPa).

In power electronics, semiconductors are based on the element silicon – but the energy efficiency of silicon carbide would be much higher.

Quantum materials that feature magnetic long-range order often reveal complex phase diagrams when localized electrons become mobile. In many materials magnetism is rapidly suppressed as electronic charges dissolve into the conduction band. In materials where magnetism persists, it is unclear how the magnetic properties are affected. 

A team of researchers generates ultra-short spin waves in an astoundingly simple material. Due to its potential to make computers faster and smartphones more efficient, spintronics is considered a promising concept for the future of electronics. In a collaboration including the Paul Scherrer Institut, a team of researchers has now successfully generated so-called spin waves much more easily and efficiently than was previously deemed possible. The researchers are presenting their results in the journal Physical Review Letters (DOI: 10.1103/PhysRevLett.122.117202).

Researchers from the Helmholtz Zentrum Berlin (HZB) and the TOMCAT beamline have achieved a new world record in time-resolved tomography by measuring over 200 tomographies per second during heating of an evolving aluminium metal foam.