In combined anomalous small angle X-ray scattering (A-SAXS) and X-ray absorption spectroscopy (XAS) measurements at the Swiss Light Source, PSI researchers working with colleagues from ETH Zurich have gained new mechanistic insight into the activity of a catalyst that is central for converting water into H₂ and O₂ - a promising route to producing clean energy. Iridium oxide is the state-of-the-art catalyst for the so-called oxygen evolution reaction (OER). The availability of the material in the Earth’s crust is extremely limited, and therefore high-surface-area iridium oxides are particularly sought after. These, however, tend to have poor operative stability. Why this is, has not been clear. The study of two high-surface-area iridium oxides under operando conditions now clarifies the mechanism behind the activity loss, by decoupling the relative contributions of different instability mechanisms to the overall deactivation.

Rockets of the European Space Agency ESA fly into space with support from the Paul Scherrer Institute PSI. Imaging carried out at PSI in cooperation with Dassault Aviation ensures the quality of certain components of the Ariane 5 and Vega launch vehicles. With the help of the neutrons generated at the neutron source SINQ, PSI researchers are screening so-called pyrotechnic components that are installed in the ESA rockets. These components, which act like fuse cords and igniters, ensure, among other things, that the booster rockets are dropped at the right hundredth of a second. The Ariane launch on 20 June took place with components that had been examined at PSI.

Direct measurements of the London penetration depth λ of Nb₃Sn, performed at PSI using the low-energy muon spin rotation (LE-μSR) technique, provide important insight into the properties of a material that might find use in future superconducting radio-frequency cavity resonators. These resonators are key components in future particle accelerators and are used in modern synchrotron sources and free-electron lasers. They are typically produced from pure niobium, but that approach is reaching fundamental and practical limits. Nb₃Sn is emerging as a promising alternative, however, in cavity tests surprising behaviour has been found: the critical fields were unexpectedly large relative to the lower critical field derived from λ values determined indirectly. The direct measurements using LE-μSR, combined with further experiments performed at the Helmholtz-Zentrum and TRIUMF, now provide a fuller picture, and confirm that Nb₃Sn cavities can indeed be operated in a metastable state above the lower critical field.

At SwissFEL, the very first transient grating spectroscopy experiment in the x-ray regime has been performed. This powerful nonlinear-optics technique is based on interfering two pulses to create a standing-wave excitation on a sample, which in turn modulates the index of refraction. The excitation dynamics is subsequently probed with a third pulse that diffracts from the transient grating. The technique has been used successfully with optical and XUV pulses, but extension to x-rays proved extremely challenging. By exploiting the Talbot effect for convergent FEL beams, a SwissFEL team collaborating with colleagues from EPFL, FERMI and MIT has now achieved x-ray transient gratings, which they probe with laser light. The experiments demonstrate bulk sensitivity and access to electronic resonances — paving the way for nonlinear optics experiments in the x-ray regime.

CALIPSOplus, a European Horizon2020 funded research and innovation program, provides access support for SMEs to light sources. The access is based on a specific review system for SMEs in parallel to the established academic access route but following the same principles. The proposal confidentiality is kept during the whole process. If the proposal is accepted, the SME will have access to the requested light sources and the experiments will be financially supported through CALIPSOplus, more information.
For industry use, SLS and SwissFEL offer direct access through the proprietary route, as well. Read more

The SINQ guide upgrade is rapidly progressing. After the 4.5m guide section closest to the cold source was successfully installed in the spring this year, work is now focused in the bunker area where the shielding walls were built and finished in July. Some of the shielding was developed in-house in cooperation with an external company and will lead to an overall reduction of the fast neutron background in the guide hall. Several guides are now being installed in the bunker and will be completed by early October. The closing of the bunker is planned for February, and the restart of SINQ in May 2020, which means we will have two proper beam cycles in 2020 with about 10 instruments.

Traditionally, transverse field µSR measurements on a high momentum decay muon beam like µE1 are complicated by the fact that the field has to be applied perpendicular to the momentum which leads to a deflection of the beam due to the Lorentz force. Accordingly, sample and detector positions always have to be adjusted with respect to the applied magnetic field. Following an approach from TRIUMF, we were recently able to obtain a 64% polarization of the muon beam by careful adjustment of the pion beam and an asymmetric excitation of quadrupole magnets in the µE1 beamline. This opens the possibility to perform transverse field µSR experiments on this high momentum beam by applying the magnetic field along the beam direction without the necessity to adjust sample or detector positions.

The ultracold neutron (UCN) source has been in operation for the last 8 years delivering UCN on a routine basis to experiments at three beam ports. The flagship experiment is the search for a permanent electric dipole moment of the neutron (nEDM), where a new result is expected soon. Following the upgrade of the control system at SINQ and in order to be compatible with PSI’s IT compliance standards, all server hardware had to be upgraded. In parallel, the entire Siemens PCS7 control software of the UCN source was upgraded from Version 7.1 to 9.0. All control sequences, most critical the ones for cool-down and cryo-operations, and user interfaces were migrated and successfully tested. This allowed the start of operation in time early June. Both control systems of SINQ and UCN are now operating with the same standard. The UCN source has been operating again reliably since beginning of July, serving experiments in area West, while in area South the new 'n2EDM' experiment is being installed.

PSI has launched a new information platform called "PSI pocket". It has been developed for the users of our large scale facilities, for guest scientists and proton therapy patients: "PSI Pocket"' summarizes important practical information not only like accelerator status and scientific highlights but also PSI phone book, orientation on the campus, the actual OASE menu and public transport from and to PSI. PSI Pocket is optimised for the use on mobile phones. Just give it a try and open the Pocket link in your web browser.

Copyright © 2019, Paul Scherrer Institut PSI

Imprint
PSI Facility News addresses the users of the PSI large facilities and appears quarterly in English. Any feedback is highly welcome! More information. 

Contact: PSI User Office, Phone: +41-56-310-4666, Email: useroffice@psi.ch