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In reply to the increasing request of structural and molecular dynamics data taken on biological samples at both high temperature and high pressure by neutron scattering techniques, we have developed a new generation of high pressure cells with the following characteristics:(1) a flat geometry to better exploit the neutron beam's cross section, (2) utilisable in the pressure range between 0 and 600 MPa and up to 100°C, (3) adapted for studies by coherent and incoherent neutron scattering, and (4) compatible with all types of neutron diffractometers and spectrometers at the Institut Laue-Langevin in Grenoble, France.Such high pressure cells permit to explore domains of pressure (p) and temperature (T ) inaccessible so far, to establish (p, T ) diagrams and determine phase transitions. They are particularly adapted to the investigation of biological systems living under extreme conditions, as for instance extremophiles living near hot vents in the deep sea, or the response of biomolecules to extreme loads.

In comparison to condensed matter, soft matter is subject to several interplaying effects (surface heterogeneities, swelling effect…) that influence transport at the nanoscale. In consequence, transport in soft and compliant materials is coupled to adsorption and deformation phenomena. The permeance of the material, i.e. the response of the material to a pressure gradient, is dependent on the temperature, the chemical potential and the external constraint. Therefore, the characterization of water dynamics in soft porous materials, that we address here, becomes much more complex. In this paper, the development of an original setup for scattering measurements of a radiation in the transmitted geometry in oedometric conditions is described. A specially designed cell enables a uniaxial compression of the investigated material, PIM-1 (Polymers of Intrinsic Microporosity), in the direction perpendicular to the applied hydraulic pressure gradient (up to 120 bars). High pressure boosting of the circulating water is performed with a commercially available high-pressure pump Karcher. This particular setup is adapted to Quasi-elastic neutron scattering technique, which enables to probe diffusion and relaxation phenomena with characteristic times of 10 -9 -10 -12 s. Moreover, it can easily be modified for other scattering techniques.

Paris-Edinburgh (PE) presses are nowadays the dominant high pressure devices for neutron scattering in the 10 GPa range and above.Here, we present developments of gasket-anvil assemblies with 30% improved pressure performance and considerably increased lifetime compared to the currently used "single-toroidal" anvils, and giving nevertheless a similar signal-to-background ratio. We also present an improved Bridgman seal package which makes the low-temperature operation of the PE press significantly more reliable. A systematic investigation of background sources in the "equatorial" scattering geometry is reported.