Improvements in neutron beam applications by using capillary neutron optics

Capillary neutron optics improve the capabilities of neutron beam techniques such as neutron depth profiling and prompt gamma activation analysis. Millions of glass capillaries are configured to capture and guide low-energy neutrons by grazing total reflection from the smooth inner surface of the hollow channels. By precise orientation of the capillaries, beams of neutrons are readily collimated with good angular control or can be finely focused - as required by the application. In addition, the optics can improve the signal-to-noise ratio by diverting a neutron beam to a convenient off-axis direction, thereby circumventing interferences from gamma rays and fast neutrons characteristic of simple aperture collimation. The focused intensity of neutrons obtained in an area of 0.03 mm2 may be increased up to a hundred times over that previously available for NDP or PGAA techniques. Furthermore, the spatial resolution can be improved by up to 100 times. Consequently, small samples, or small volumes within larger samples, may be better and more rapidly investigated with neutron probe techniques. We report on developments in the application of capillary neutron optics.