5-3. Advances in spatial resolution, temporal and contrast resolutions of neutron imaging at the Paul Scherrer Institut, Switzerland

Pavel Trtik

Neutron Imaging and Applied Materials Group, Paul Scherrer Institut, Switzerland

Abstract: Neutron imaging is a viable complementary technique to other imaging modalities, such as X-ray imaging. As in the case of all other techniques there is a constant demand for the enhancement of its resolution capabilities. Within the framework of the ‘PSI Neutron Microscope’ (‘NM’) project, the spatial resolution of neutron imaging was pushed down to the sub-5 micrometres domain in 2D and below 10 micrometres in 3D.

Based on this advancement, the ‘NM’ detector was included in the standard user programme as an add-on detector available at the ICON and the POLDI beamlines at the Paul Scherrer Institut (PSI), Switzerland. The successful applications of the ‘NM’ include but are not limited to the hydrogen quantification in zirconium nuclear fuel claddings, the assessment of coating distribution on gas diffusion layers for polymer electrolyte fuel cells, and the visualization of cavitation in realistic Diesel injection nozzles, the pore size distribution in additively manufactured gold with 10 µm resolution an accomplishment hardly amenable by other non-destructive techniques while being highly industrially relevant.

On the temporal scale, the resolution as been recently extended to nearly 1000 frames per second (albeit at lower spatial resolution) which enabled useful investigations of various types of flows (e.g. air-water two phase flow, Argon bubble flows in liquid metals). The quantitativeness of the neutron imaging has been recently enhanced by the so-called black body correction thus allowing for the high fidelity assessment of attenutaion coefficients. This has become a useful tool for all the investigations in which the quantitative values of material compositions are in the focus of scientific questioning.