How to probe tiny samples? Insights into the production of micron-sized cold neutron beams

NMI3, 09/07/2015
Source: http://nmi3.eu

The NMI3 Imaging JRA discusses how to produce smaller beams. They conclude that reflective optics offers the most versatile way to produce them.

Dumbbell String String of small magnetic dumbbell (100nm long)

Neutron beams for condensed matter studies are traditionally big, macroscopic beams, mostly because of the limited neutron flux. However to probe small samples with a high spatial resolution by neutron imaging, it is necessary to use micro-sized (1–50 µm) thermal or cold neutron beams. A group of scientists from France, Russia and Spain have just published a paper where they discuss various possibilities to produce such micro-sized neutron beams. This work is conducted within the NMI3 Imaging Joint Research Activity.

In the paper they describe three ways of producing sub-100 µm thermal neutron beams by using:

collimation slits
reflected beams
neutron waveguides

They concluded that reflective optics offers the most versatile way to produce tiny neutron beams while also enhancing signal-to-background ratio. With this technique the size of the micro-beam can be easily tuned by simply rotating the reflecting mirror. Being able to work off the direct beam provides an excellent signal/noise ratio even if the incident neutron intensities are low. The scheme will be tested on the new radiography station IMAGINE at the Laboratoire Léon Brillouin in France.

Original Publication

F. Ott, S. Kozhevnikov, A. Thiaville, J. Torrejon, M. Vázquez,
Shaping micron-sized cold neutron beams
Nuclear Instruments and Methods in Physics Research Section A, 788, 29–34 (2015),
doi:10.1016/j.nima.2015.03.057

NMI3 support

This work is supported by NMI3 through the Imaging JRA.