In this overview article, we present the main features of the upgraded ID27 beamline which is fully optimised to match the exceptional characteristics of the new Extremely Bright Source (EBS) of the European Synchrotron Radiation Facility (ESRF). The ID27 beamline has been converted to a 120-m-long instrument and has undergone a major refurbishment of all its critical components including both hardware and software environments. We will successively introduce the ID27 undulator X-ray source, optical scheme and the main components of the experimental hutch. We will illustrate the potential of this new instrument through some selected research examples.

ID15A is a newly refurbished beamline at the ESRF devoted to operando and time-resolved diffraction and imaging, total scattering and diffraction computed tomography. The beamline is optimized for rapid alternation between the different techniques during a single operando experiment in order to collect complementary data on working systems. The high available energy (up to 120 keV) means that even bulky and highly absorbing systems may be studied. The beamline is equipped with optimized focusing optics and a photon-counting CdTe pixel detector, allowing for both unprecedented data quality at high energy and for very rapid triggered experiments. A large choice of imaging detectors and ancillary probes and sample environments is also available.

A multiple-analyser-crystal spectrometer for non-resonant inelastic X-ray scattering spectroscopy installed at beamline ID16 of the European Synchrotron Radiation Facility is presented. Nine analyser crystals with bending radii R = 1 m measure spectra for five different momentum transfer values simultaneously. Using a two-dimensional detector, the spectra given by all analysers can be treated individually. The spectrometer is based on a Rowland circle design with fixed Bragg angles of about 88 degrees . The energy resolution can be chosen between 30-2000 meV with typical incident-photon energies of 6-13 keV. The spectrometer is optimized for studies of valence and core electron excitations resolving both energy and momentum transfer.

At the ESRF, 17 Beamlines are equipped with liquid nitrogen cooled monochromators. Liquid nitrogen (LN2) enables to cool the silicon crystals down to a temperature range where the thermal properties of the Silicon are favourable, and, consequently to reduce the thermal deformation induced by the beam heat load. In most cases, indirect cooling is applied: liquid nitrogen flows inside copper blocks, which are clamped to the sides of the crystals. The heat flow is evacuated from the crystal though the silicon – copper interface, with possibly some intermediate material like indium or indium-gallium, intended to improve the thermal contact. In order to suppress this thermal resistance, some attempts have been made to implement direct cooling: channels are machined in the Silicon crystal, and the liquid nitrogen flows directly inside the Silicon channels. This requires a vacuum tight sealing between the silicon block and the metallic LN2 feeding pipes. In a first part, calculations results are presented, enabling to assess the gain that can be expected from direct cooling, compared to the classical indirect side cooling technique. In a second part, based on a few crystals assemblies in use at the ESRF, the critical points associated with indirect side cooled and with directly cooled crystals are described. 1. Influence of the cooling on the crystal deformation

The performance of an indirectly cooled cryogenic silicon monochromator under heat loads up to 870 W has been studied. The investigation was performed over numerous parameters and included measurements of total flux, spectral density, rocking curves, angular beam profiles and crystal slope errors. An almost ideal monochromator performance was observed in the 270-570 W range of the heating power. At a heat load of approximately 400 W and under standard operation conditions, the crystal distortions did not exceed 1 micro rad. At the highest available heat load of 870 W, the crystal distortions were about 7 micro rad.