title: Bose-Einstein condensation of metastable helium.
abstract: We have observed a Bose-Einstein condensate in a dilute gas of 4He in the (3)2S(1) metastable state. We find a critical temperature of (4.7+/-0.5) microK and a typical number of atoms at the threshold of 8 x 10(6). The maximum number of atoms in our condensate is about 5 x 10(5). An approximate value for the scattering length a = (16+/-8) nm is measured. The mean elastic collision rate at threshold is then estimated to be about 2 x 10(4) s(-1), indicating that we are deeply in the hydrodynamic regime. The typical decay time of the condensate is 2 s, which places an upper bound on the rate constants for two-body and three-body inelastic collisions.
authors.affiliation: Collège de France, Laboratoire Kastler Brossel, Département de Physique, Ecole Normale Supérieure, 24 rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: F
authors.initials: F
authors.lastname: Pereira Dos Santos
authors.forename: J
authors.initials: J
authors.lastname: Léonard
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: C J
authors.initials: CJ
authors.lastname: Barrelet
authors.forename: F
authors.initials: F
authors.lastname: Perales
authors.forename: E
authors.initials: E
authors.lastname: Rasel
authors.forename: C S
authors.initials: CS
authors.lastname: Unnikrishnan
authors.forename: M
authors.initials: M
authors.lastname: Leduc
authors.forename: C
authors.initials: C
authors.lastname: Cohen-Tannoudji