title: Diffraction of neutral helium clusters: evidence for "magic numbers".
abstract: The size distributions of neutral 4He clusters in cryogenic jet beams, analyzed by diffraction from a 100 nm period transmission grating, reveal magic numbers at N=10-11, 14, 22, 26-27, and 44 atoms. Whereas magic numbers in nuclei and clusters are attributed to enhanced stabilities, this is not expected for quantum fluid He clusters on the basis of numerous calculations. These magic numbers occur at threshold sizes for which the quantized excitations calculated with the diffusion Monte Carlo method are stabilized, thereby providing the first experimental confirmation for the energy levels of 4He clusters.
authors.affiliation: Max-Planck-Institut für Strömungsforschung, Bunsenstrasse 10, 37073 Göttingen, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Brühl
authors.forename: Rafael
authors.initials: R
authors.lastname: Guardiola
authors.forename: Anton
authors.initials: A
authors.lastname: Kalinin
authors.forename: Oleg
authors.initials: O
authors.lastname: Kornilov
authors.forename: Jesús
authors.initials: J
authors.lastname: Navarro
authors.forename: Tim
authors.initials: T
authors.lastname: Savas
authors.forename: J Peter
authors.initials: JP
authors.lastname: Toennies