Scientific Highlights from PSI's research divisions
Research with Neutrons and Muons (NUM)
Electronic systems with flat bands are predicted to be a fertile ground for hosting emergent phenomena including unconven- tional magnetism and superconductivity, but materials that manifest this feature are rare. Here, we use scanning tunnelling microscopy to elucidate the atomically resolved electronic states and their magnetic response in the kagome magnet Co3Sn2S2.
Understanding and controlling the electronic structure of thin layers of quantum materials is a crucial first step towards designing heterostructures where new phases and phenomena, including the metal-insulator transition (MIT), emerge. Here, we demonstrate control of the MIT via tuning electronic bandwidth and local site environment through selection of the number of atomic layers deposited.
Photon Science Division (PSD)
On 1st January 2019, the European Horizon 2020 project BEAmline for Tomography at SESAME (BEATS) was launched with the objective to design, procure, construct and commission a beamline for hard X-ray full-field tomography at the SESAME synchrotron in Jordan. The European grant is worth 6 million euros and will span a four-year period from beginning 2019 to end 2022.
Biology and Chemistry (BIO)
In the service of health, scientists at the Paul Scherrer Institute PSI work with radionuclides and develop agents to treat cancer and to detect tumours. Their research provides support to hospitals and is of great interest to Swiss industry.
At the treatment stations of the Centre for Proton Therapy at PSI, tumours can be precisely irradiated from any direction. An interactive graphic explains how the protons get from the source to the body in order to trigger the elimination of tumour tissue.
General Energy (ENE)
Kinetics and Mechanism of Metal Nanoparticle Growth via Optical Extinction Spectroscopy and Computational Modeling: The Curious Case of Colloidal Gold
An overarching computational framework unifying several optical theories to describe the temporal volution of gold nanoparticles (GNPs) during a seeded growth process is presented. To achieve this, we sed the inexpensive and widely available optical extinction spectroscopy, to obtain quantitative kinetic data. In situ spectra collected over a wide set of experimental conditions were regressed using the hysical model, calculating light extinction by ensembles of GNPs during the growth process. This model rovides temporal information on the size, shape, and concentration of the particles, and any electromagnetic interactions between them. Consequently, we were able to describe the mechanism of GNP growth and divide the process into distinct genesis periods. We provide explanations for several longstanding mysteries, e.g., the phenomena responsible for the purple-greyish hue during the early stages of GNP growth, the complex interactions between nucleation, growth and aggregation events, and a clear distinction between agglomeration and electromagnetic interactions. The presented theoretical formalism has been developed in a generic fashion so that it can readily be adapted to other nanoparticulate formation scenarios such as the genesis of various metal nanoparticles.
Recent advances in electron crystallography published in Angewandte Chemie and highlighted by Science, Chemical & Engineering News and ScienceNews!Under the lead of LSK member, "Rapid structure determination of microcrystalline molecular compounds using electron diffraction", published in Angewandte Chemie International Edition https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201811318 has attracted great attention in the chemistry community.
Nuclear Energy and Safety Research (NES)
The EU Horizon 2020 program granted 3.5 million Euros to the research and innovation project SAMOSAFER, where PSI is one of the 14 project partners. The total budget of the project, inclusive own and in-kind contributions, is 4.5 million Euros. The aim of SAMOSAFER project is to develop and demonstrate new safety barriers and a more controlled behaviour in severe accidents of the Molten Salt Reactor (MSR). Three groups at PSI will be involved in the project: the LSM groups for Advanced Nuclear Systems (ANS) and Multiscale Materials Modelling (MMM) and the Severe Accidents Research group (Sacre) of LRT, focusing on redistribution of the source term in the fuel treatment unit of MSR and assessment and reduction of radionuclide mobility during accidental conditions.
Dr Christopher Mudry, who joined PSI in 1999 and is Research Group Leader of the Condensed Matter Theory Group at PSI since 2009, was awarded the title of Adjunct Professor at EPF Lausanne with the following citation. "Dr Christopher Mudry is a highly acclaimed theoretical physicist. He is regarded as one of the world’s leading experts on the quantum field theory of condensed matter and in the rapidly developing field of the topological properties of matter."
X-band (12 GHz) radio-frequency (RF) accelerating structures are under consideration for future free electron lasers, medical linacs and linear colliders. Two such structures, built by PSI in the framework of a CERN/PSI collaboration, are currently being tested at high power at CERN.
A team of GFA and CPT physicists has worked out a novel achromatic beam optics concept for a proton therapy gantry. The article on the concept in the journal Zeitschrift für Medizinische Physik has been awarded a prize for the best publication in 2016. The jury states: „The paper of Alexander Gerbershagen et al. entitled „A novel beam optics concept in a particle therapy gantry utilizing the advantages of superconducting magnets” describes a new concept of a first order design of the beam optics of a superconducting proton therapy gantry beam. The jury was impressed by the well-structured experimental work with clear improvement of large momentum acceptance in the gantry which opens the possibility of implementation new and faster dose application techniques in proton therapy.”