[en] First results obtained with prototypes of a new type of beam profile monitor based on semi-transparent CVD-diamond are presented. The devices consists of a few micrometer thin membrane on a Si-substrate. Ti/Al-pixel are generated lithographically on the membrane while the signal wires are deposited on a dielectric in order to minimise signal pickup. Synchrotron radiation tests at 8 keV showed good signal homogeneity, spatial resolution and linearity for low resistivity diamond membranes. Considerable difficulties were encountered in the test of a detector grade diamond membrane. They are most likely related to enhanced surface conductivity and capacitive effects

[en] For the three macromolecular crystallography beamlines of the Swiss Light Source, a new unified diffractometer – D3 – was developed. We present details of the engineering and implementation of the project components that were fabricated in-house by the design facilities of the Paul Scherrer Institute (PSI). Key components of the diffractometer project were custom designed at PSI including a microspectrophotometer for sample viewing and optical spectros-copy and a combined Köhler and spectroscopic illumination lamp. In addition, all elements for beam steering and shaping such as an exposure box and multiple articulated elements for beam shaping and beam diagnostics were designed in-house. Further components are the positioners for cryo-cooling devices, and an X-ray-fluorescence detector. For minimization of vibrations, a combined mineral cast and granite block design was employed for the diffractometer table. Due to the restricted space of the sample environment, a high degree of integration of the D3 instrumentation had to be achieved. Devices to be considered in the integration concept are the robotic sample changer, the area detector and the new multi-axis goniometer PRIGo. Optimization strategies include kinematic simulations to describe the kinematic hull structure of the sample positioning and to reduce possible collisions. Additionally, flexure designs were used to allow adjustability while satisfying space constraints.

[en] Radiation induced damage of metal centres in proteins is a severe problem in X-ray structure determination. Photoreduction can lead to erroneous structural implications, and in the worst cases cause structure solution to fail. Resonance Raman (RR) spectroscopy is well suited in-situ monitoring of X-ray induced photoreduction. However the laser excitation needed for RR can itself cause photoreduction of the metal centres. In the present study myoglobin and rubredoxin crystals were used as model systems to assess the feasibility of using RR for this application. It is shown that at least 10-15 RR spectra per crystal can be recorded at low laser power before severe photoreduction occurs. Furthermore it is possible to collect good quality RR spectra from cryocooled protein crystals with exposure times of only a few seconds. Following extended laser illumination photoreduction is observed through the formation and decay of spectral bands as a function of dose. The experimental setup planned for integration into the SLS protein crystallography beamlines is also described. This setup should also prove to be very useful for other experimental techniques at synchrotrons where X-ray photoreduction is a problem e.g. X-ray absorption spectroscopy

[en] SwissFEL requires the monitoring of the photon spectral distribution at a repetition rate of 100 Hz for machine optimization and experiment online diagnostics. The Photon Single Shot Spectrometer has been designed for the photon energy range of 4 keV to 12 keV provided by the Aramis beamline. It is capable of measuring the spectrum in a non-destructive manner, with an energy resolution of Δ  E / E  = (2–5) × 10"−"5 over a bandwidth of 0.5% on a shot-to-shot basis. This article gives a detailed description about the technical challenges, structures, and considerations when building such a device, and to further enhance the performance of the spectrometer.

[en] Neutron diffraction and X-ray absorption measurements have been performed to study the changes in the structure and the Ce valence between 10 K and 295 K. No evidence for a phase transition was obtained, but some nearest-neighbour distances have clear peculiarities in the temperature range of 100 K to 150 K. The valence of Ce increases continuously with decreasing temperature, which can explain neither the lattice anomalies nor the previously observed temperature dependence of the phonon frequencies. A correlation between the gap-like magnetic excitation spectrum formed at low temperatures and observed lattice anomalies is discussed. (orig.)