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The SwissFEL beam-synchronous data-acquisition system is based on several novel concepts and technologies. It is targeted on immediate data availability and online processing and is capable of assembling an overall data view of the whole machine, thanks to its distributed and scalable back-end. Load on data sources is reduced by immediately streaming data as soon as it becomes available. The streaming technology used provides load balancing and fail-over by design. Data channels from various sources can be efficiently aggregated and combined into new data streams for immediate online monitoring, data analysis and processing. The system is dynamically configurable, various acquisition frequencies can be enabled, and data can be kept for a defined time window. All data is available and accessible enabling advanced pattern detection and correlation during acquisition time. Accessing the data in a code-agnostic way is also possible through the same REST API that is used by the web-frontend. We will give an overview of the design and specialities of the system as well as talk about the findings and problems we faced during machine commissioning., Proceedings of the 16th Int. Conf. on Accelerator and Large Experimental Control Systems, ICALEPCS2017, Barcelona, Spain

The SwissFEL is a new free electron laser facility at the Paul Scherrer Institute (PSI) in Switzerland. Commissioning started in 2016 and resulted in first lasing in December 2016 (albeit not on the design energy). In 2017, the commissioning continued and will result in the first pilot experiments at the end of the year. The close interaction of experiment and accelerator components as well as the pulsed electron beam required a well thought out integration of the control system including some new concepts and layouts. This paper presents the current status of the control system together with some lessons learned., Proceedings of the 16th Int. Conf. on Accelerator and Large Experimental Control Systems, ICALEPCS2017, Barcelona, Spain

The ultrafast response of singly negatively charged C60 fullerene in solution has been investigated by femtosecond pump-probe absorption spectroscopy and transient anisotropy in the visible and near-infrared region. Pump excitation within the near-infrared band demonstrates that this spectral feature can be described as avibrational progression associated with asingle electronic transition. Relaxation of the first electronically excited state occurs primarily by internal conversion with atime constant of 3ps, slightly depending on the solvents, tetrahydrofuran or o-dichlorobenzene, and also on the excitation wavelength. An excitation of the second electronically excited state around 530nm leads to an ultrafast internal conversion to the first excited state with apulse-limited time constant of less than 100fs. As aminor channel, stimulated emission in the spectral regime of 1150-1300nm was observed from the first electronically excited state both after near-infrared and visible excitation. After internal conversion to the electronic ground state, C60− dissipates its excess internal energy into the solvent on alonger timescale of 40-70ps. The transient anisotropy associated with directly populating the first excited state reveals an ultrafast component decaying within 100fs, which is attributed to ultrafast vibrational motions, conceivably arising from excited state pseudorotation

Recently, the installation of the components for the free electron laser SwissFEL has started at the Paul Scherrer Institute (PSI). In March 2016, beginning of the injector commissioning is planned and first lasing is foreseen a year later. New hardware, like VME64x-boards (IFC 1210, an P2020 based intelligent FPGA controller from IOxOS) and -crates (Trenew), timing system (from MRF with advanced features), motion controllers (Power PMAC from Delta Tau, and MDrive from Schneider), among others, as well as modern field buses, pose great challenges to the controls team. The close interaction of machine- and experiment-components require advanced software concepts for data-acquisition, -distribution, and -archiving. An overview of the project will be presented and the different HW and SW solutions based on the experience gained from preliminary implementations at other facilities of PSI will be explained. First results of the HW commissioning at the SwissFEL will be reported., Proceedings of the 15th Int. Conf. on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2015, Melbourne, Australia

In dieser Arbeit wurde die Relaxationsdynamik des ersten elektronisch angeregten Zustandes von Fullerid-Anionen sowie von längenselektierten CNT in Lösung mittels fs-Spektroskopie durchgeführt. Für die Dynamik der Fulleride konnten zwei Zeitkonstanten bestimmt werden, welche der elektronischen sowie Schwingungsrelaxation des Anions/Dianions zugeordnet wurden. Im Fall der CNT konnte gezeigt werden, dass ein Zusammenhang zwischen Lebensdauer des angeregten Zustandes und der Länge der CNT besteht.