Articles you may be interested inAn evaluation of high energy bremsstrahlung background in point-projection x-ray radiography experimentsa) Rev. Sci. Instrum. 83, 10E528 (2012); 10.1063/1.4738649 High-energy, high-resolution x-ray imaging on the Trident short-pulse laser facilitya) Rev. Sci. Instrum. 79, 10E905 (2008); 10.1063/1.2965012Cross-sectional insight in the water evolution and transport in polymer electrolyte fuel cellsThe authors report on in situ investigations of liquid water evolution and transport in an undisturbed operating fuel cell at the microscopic level. Synchrotron x-ray radiography enhances the spatial resolution by two orders of magnitude compared to the state-of-the-art techniques in this field. The primary spots of liquid water formation, their growth, and transport inside the porous gas diffusion material were analyzed; correlations between operating conditions and the dynamics of droplet formation are described. Previous findings from modeling and simulation approaches are confirmed and the applicability for the description of in situ processes of a recently proposed model has been proven.

Neutron imaging can provide two- or three-dimensional, spatially resolved images of the internal structure of bulk samples that are not accessible by other techniques, making it a unique tool with many potential applications. The method is now well established and is available at neutron sources worldwide. This review will give a survey of the technique of neutron imaging with a special focus on neutron tomography; the basics of the method as well as the technology of instrumentation will be outlined, and the techniques will be illustrated by representative applications. While the first part of the paper focuses on conventional attenuation contrast imaging, the second part reviews and critically assesses recent methodical developments.

Neutrons are highly sensitive to magnetic fields owing to their magnetic moment, whereas their charge neutrality enables them to penetrate even massive samples. The combination of these properties with radiographic and tomographic imaging [1][2][3][4] enables a technique that is unique for investigations of macroscopic magnetic phenomena inside solid materials. Here, we introduce a new experimental method yielding twoand three-dimensional images that represent changes of the quantum-mechanical spin state of neutrons caused by magnetic fields in and around bulk objects. It opens up a way to the detection and imaging of previously inaccessible magnetic field distributions, hence closing the gap between high-resolution two-dimensional techniques for surface magnetism 5,6 and scattering techniques for the investigation of bulk magnetism 7-9 . The technique was used to investigate quantum effects inside a massive sample of lead (a type-I superconductor).The specific interaction of neutrons with matter enables neutron radiography to complement X-ray imaging methods for analysing materials 1 . Conventional radiography is a geometrical projection technique based on the attenuation of a beam by a sample along a given ray. Quantum mechanically, neutrons are described by de Broglie wave packets 10 whose spatial extent may be large enough to produce interference effects similar to those known from visible laser light or highly brilliant synchrotron X-rays. Measurements of the neutron wave packet's phase shift induced by the interaction with matter have a long and distinguished history [11][12][13][14] and were recently combined with neutron imaging approaches, where two-and three-dimensionally resolved spatial information about the quantum mechanical interactions of neutrons with matter was obtained 2,3,15 . In addition, neutrons, which from the particle-physicist's point of view are small massive particles with a confinement radius of about 0.7 fm, possess another outstanding property: a magnetic moment µ (µ = −9.66 × 10 −27 J T −1 ). The magnetic moment is antiparallel to the internal angular momentum of the neutron described by a spin S with the quantum number s = 1/2. Consequently, the high sensitivity of neutrons to magnetic interactions has extensively been and is still being exploited in numerous experiments to study fundamental magnetic properties and to understand basic phenomena in condensed matter 7-9 . Here, we present an experimental method that combines spin analysis with neutron imaging and yields a new contrast mechanism for neutron radiography that enables two-and three-dimensional investigations of magnetic fields in matter. This method is unique not only in that it provides spatial information about the interaction of the spin with magnetic fields but also in its ability to measure these fields within the bulk of materials, which is not possible by any other conventional technique.Our concept is based on the fact that any spin wavefunction corresponds to a definite spin direction and by using the Schrödin...

The evolution of liquid water and its transport through the porous gas diffusion media in an operating fuel cell were investigated applying an experimental setup for high spatial resolution of 3 m. Fundamental aspects of cluster formation in hydrophobic/hydrophilic porous materials as well as processes of multiphase flow are addressed. The obtained water distributions provide a detailed insight in the membrane electrode assembly and the porous electrode with regard on the existence and transport of liquid water. In addition, the results approve transport theories used within the framework of percolation theory and demonstrate the need for adapted modeling approaches.