The accumulator ring structure bunches and intensifies the ion beam for delivery onto the mercury target to produce the pulsed neutron beams. The intense H- beam from the linac must be sharpened more than 1,000 times to produce the extremely short, sharp bunch of neutrons needed for optimal neutron-scattering research. To accomplish this, the H- pulse from the linac is wrapped into the ring through a diamond stripper foil that strips the electrons from the negatively charged hydrogen ions to produce the protons (H+) that circulate in the ring. Approximately 1,200 turns are accumulated, and then all these protons are “kicked” out at once, producing a pulse less than 1 millionth of a second (10-6seconds) in duration that is delivered to the target. In this way, short, intense proton pulses are produced, stored, and extracted at a rate of 60 times a second to bombard the target. 

https://neutrons.ornl.gov/content/how-sns-works