For the investigation of mechanical residual strain in rocks (first, second and third order strain), the deformation of crystalline lattice of the rock-forming minerals is determined.
A wide variety of experimental environments (e.g. uniaxial press, triaxial setup with pore pressure TRIXI) are available to determine the deformation mechanisms of rocks under various stress conditions. As the in-situ deformation is determined, properties which are not directly accessible by macroscopic methods (e.g. pore pressure stress coupling – Biot-alpha).
To address these issues, the Strain/Stress Diffractometer EPSILON (cf. video) was developed to operate on a pulsed neutron source. With these pulsed neutrons, a broad neutron energy spectrum is available, so that the method is called energy-dispersive. It is therefore particularly suitable for the investigation of low-symmetry minerals in polyphase rock samples.