title: Direct mass measurement of the four-neutron halo nuclide 8He.
abstract: A high-precision Penning trap mass measurement of the exotic 8He nuclide (T(1/2)=119 ms) has been carried out resulting in a reduction of the uncertainty of the halo binding energy by over an order of magnitude. The new mass, determined with a relative uncertainty of 9.2 x 10(-8) (deltam=690 eV) is 13 keV less bound than the previously accepted value. The mass measurement is of great relevance for the recent charge-radius measurement of 8He [P. Mueller, Phys. Rev. Lett. 99, 252501 (2007).10.1103/PhysRevLett.99.252501]. The 8He mass is the first result from the newly-commissioned Penning trap: TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at the ISAC (Isotope Separator and Accelerator) radioactive beam facility at TRIUMF.
authors.affiliation: TRIUMF, 4004 Wesbrook Mall, Vancouver BC, Canada V6T 2A3.
authors.forename: V L
authors.initials: VL
authors.lastname: Ryjkov
authors.forename: M
authors.initials: M
authors.lastname: Brodeur
authors.forename: T
authors.initials: T
authors.lastname: Brunner
authors.forename: M
authors.initials: M
authors.lastname: Smith
authors.forename: R
authors.initials: R
authors.lastname: Ringle
authors.forename: A
authors.initials: A
authors.lastname: Lapierre
authors.forename: F
authors.initials: F
authors.lastname: Ames
authors.forename: P
authors.initials: P
authors.lastname: Bricault
authors.forename: M
authors.initials: M
authors.lastname: Dombsky
authors.forename: P
authors.initials: P
authors.lastname: Delheij
authors.forename: D
authors.initials: D
authors.lastname: Lunney
authors.forename: M R
authors.initials: MR
authors.lastname: Pearson
authors.forename: J
authors.initials: J
authors.lastname: Dilling