title: Rotational Effects of Nanoparticles for Cooling down Ultracold Neutrons.
abstract: Due to quantum coherence, nanoparticles have very large cross sections when scattering with very cold or Ultracold Neutrons (UCN). By calculating the scattering cross section quantum mechanically at first, then treating the nanoparticles as classical objects when including the rotational effects, we can derive the associated energy transfer. We find that rotational effects could play an important role in slowing down UCN. In consequence, the slowing down efficiency can be improved by as much as ~40%. Since thermalization of neutrons with the moderator requires typically hundreds of collisions between them, a ~40% increase of the efficiency per collision could have a significant effect. Other possible applications, such as neutrons scattering with nano shells and magnetic particles,and reducing the systematics induced by the geometric phase effect using nanoparticles in the neutron Electric Dipole Moment (nEDM), are also discussed in this paper.
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Tu
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Guangai
authors.initials: G
authors.lastname: Sun
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Gong
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Liu
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.|State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang, 621010, People's Republic of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Penglin
authors.initials: P
authors.lastname: Gao
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: Wenzhao
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, 621999, People's Republic of China.
authors.forename: H
authors.initials: H
authors.lastname: Yan