In-beam Mössbauer spectra of Mn implanted into lithium aluminum hydride.

In-beam Mössbauer spectra of Mn implanted into LiAlH were measured at different temperatures between 17 and 300 K. The Mössbauer spectrum measured at 17 K showed two sets of doublets, which were assigned to Fe atoms at substitutional sites at Al and Li sites. The Debye temperatures θ for the Fe atoms at Al-substituted and Li-substituted sites were estimated to be 194 K and 117 K, respectively.

Spallation ultracold neutron source of superfluid helium below 1 K.

For the production of high-density ultracold neutrons (UCNs), we placed 0.8 K superfluid helium in a cold neutron moderator. We resolved previous heat-load problems in the spallation neutron source that were particularly serious below 1 K.