New results on energy-selective neutron radiography show vast potential for new materials science and engineering research according to a European research collaboration.
Neutron radiography is a powerful, non-destructive imaging technique that takes advantage of the high penetrating power of neutrons and the strong contrast with hydrogen containing materials. Elegant demonstration examples have been made to show the uniqueness of the information: petrol flowing in operating engine cylinders, fossil plants bound up inside rocks, and coffee brewing in a stove-top espresso maker. More practically the neutron radiography technique has applications ranging from the electro-chemical behaviour of fuel cells through to the investigation of plant–soil interactions.
The research group has carried out extensive tests with a variation of the standard ‘white-beam’ radiography technique. Writing in the journal Nuclear Instruments and Methods they say that their ‘energy selective’ imaging technique has considerable advantages and potential compared to the standard method [Lehmann et al., Nucl. Inst. Methods (2009) A603, 429].
With modern neutron imaging systems capable of creating high-quality images in a few minutes, the group says that developing advanced neutron imaging capability at pulsed neutron sources like ISIS should be an important goal for facility managers and the research community.
Neutron radiography can be used for mapping structural properties such as crystallographic texture and residual strains with high spatial resolution. The new method relies on the sudden decrease of neutron transmission in the vicinity of Bragg diffraction edges, providing enhanced contrast. New features were made visible relating to microcrystalline variations in test materials containing Fe, Al and Cu.
Designs for a dedicated imaging beamline (Imat) are already underway at the ISIS neutron source. Construction of the new instrument at the ISIS Second Target Station is expected to take place in the next two years.
The research group is made up of members from the ISIS neutron source in the UK, the Paul-Scherrer Institut, Switzerland and the Helmholtz Centre Berlin in Germany.