There are many distinct methods of producing sufficiently strong neutron beams for science. Because of their flux (see below), that is higher by several orders of magnitude, nuclear reactors and spallation sources are nowadays preferred to radioisotope, photon or accelerator sources. (AUSTRON )

Finally, the pulsed proton beam will be directed onto a liquid mercury target, where 60-Hz pulses of neutrons will be created through spallation reactions of the protons with the mercury nuclei. (Spallation Neutron Source)

With the world's highest flux reactor-based neutron source (the High Flux Isotope Reactor) and the world's most intense pulsed accelerator-based neutron source (the Spallation Neutron Source), ORNL provides neutron scattering capabilities unavailable anywhere else in the world. (Oak Ridge National Laboratory)