Abstract: The invention relates to a composite material storing hydrogen. Said composite material can alternate, in an essentially reversible manner, between a storage state and a non-storage state and optionally at least on intermediate state. In the storage state thereof, the system comprises the following constituents: (a) at least one first hydride constituent and (b) at least one second constituent that is at least one hydrogen-free constituent and/or one other hydride constituent. The at least one first hydride constituent and the at least one second constituent are in a first solid multiphase system, and during the changeover to the non-storage state of the system, the at least one first hydride constituent reacts with the at least one second constituent, forming H2, in such a way that, in the non-storage state, at least one other hydrogen-free compound and/or alloy is formed and another solid multiphase system is created.

Abstract: An X-ray analysis apparatus having a curved paraboloid-shaped curved graded multilayer Bragg reflector (5) is characterized in that the layers of the reflector (5) are directly introduced onto a concave curved surface of a paraboloid-shaped hollow substrate and a maximum allowable shape deviation for the concave substrate surface facing the reflector is &Dgr;p={square root over (2px)} &Dgr;&thgr;R, and having a maximum allowable waviness Δ ⁢   ⁢ y Δ ⁢   ⁢ x = 1 2 ⁢ Δθ R and a maximum allowable roughness &Dgr;y=d/2&pgr;, preferentially &Dgr;y≦0.