Experimental Study of Ultracold Neutron Localization and Sub-Barrier Penetration

摘要

Free ultracold neutrons (UCN) may be stored in magnetic or material''bottles'' by total internal reflection and via the small neutron magnetic dipole moment. However, the storage time for these UCN is much smaller than predicted by theory and cannot be attributed to normal radioactive decay of the particle. One explanation for this short storage time has been so-called ''states of localization'' of sub-barrier UCN at inhomogeneities in the reflection materials. This theory assumes enhanced absorption and upscattering by hydrogen impurities and higher than expected penetration of the sub-barrier UCN in foil materials. The original NEER-supported project proposed to investigate UCN using a LANL developed source. Unfortunately, this source was placed in standby at the earliest stage of the project due to funding redirection at LANL. Ultimately, the source was decommissioned as LANL investigated other methods of UCN production. Attempts to derive an UCN beam from the UT TRIGA reactor were unsuccessful and not directly supported by the NEER project.