Page "Neutron scattering" Paragraph 7

Achieving a precise velocity, ie.

a precise energy & de Broglie wavelength, of the neutron beam is important.

Such single-energy beams are termed ' monochromatic '.

Monochromaticity is achieved either with a crystal monochromator or a time of flight spectrometer.

In the time-of-flight technique, neutrons are sent through a sequence of two rotating slits, so that only neutrons of a particular velocity are selected.

Recently there has been the development of spallation sources which can create a rapid pulse of neutrons.

In this method, the pulse contains neutrons of many different velocities / de Broglie wavelengths.

However, the velocities of the scattered neutrons can be determined afterwards by measuring the time of flight of the neutrons between the sample and neutron detector.