Compact ultracold neutron source concept for low-energy accelerator-driven neutron sources

Abstract

The concept of a small-scale, pulsed-proton accelerator-based compact ultracold neutron (UCN) source is presented. The essential idea of the compact UCN source is to enclose a volume of superfluid He-4 converter with a supercold moderator in the vicinity of a low-radiation neutron production target from (p, n) reactions. The supercoldmoderator should possess an ability to produce cold neutron flux with a peak brightness near the single-phonon excitation band of the superfluid He-4 converter, thereby augmenting the UCN production in the compactUCNsource even with very lowintensity of neutron brightness. The performance of the compact UCN source is studied in terms of the UCN production and thermal load in the UCN converter. With the proposed concept of the compact UCN source, a UCN production rate of P-UCN = 80 UCN/cm(3)/s in the UCN converter could be obtained while maintaining thermal load of the superfluid He-4 and its container at a level of 22 mW. This study shows that the compact UCN source can produce a high enough density of UCNs at a small-scale, low-energy, pulsed-proton beam facility with reduced efforts on the cooling and radiation protection.