title: Ultrarelativistic-positron-beam transport through meter-scale plasmas.
abstract: We report on the first study of the dynamic transverse forces imparted to an ultrarelativistic positron beam by a long plasma in the underdense regime. Focusing of the 28.5 GeV beam is observed from time-resolved beam profiles after the 1.4 m plasma. The strength of the imparted force varies along the approximately 12 ps full length of the bunch as well as with plasma density. Computer simulations substantiate the longitudinal aberration seen in the data and reveal mechanisms for emittance degradation.
authors.affiliation: Stanford Linear Accelerator Center, Stanford, California 94309, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Hogan
authors.forename: C E
authors.initials: CE
authors.lastname: Clayton
authors.forename: C
authors.initials: C
authors.lastname: Huang
authors.forename: P
authors.initials: P
authors.lastname: Muggli
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: B E
authors.initials: BE
authors.lastname: Blue
authors.forename: D
authors.initials: D
authors.lastname: Walz
authors.forename: K A
authors.initials: KA
authors.lastname: Marsh
authors.forename: C L
authors.initials: CL
authors.lastname: O'Connell
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Iverson
authors.forename: F-J
authors.initials: FJ
authors.lastname: Decker
authors.forename: P
authors.initials: P
authors.lastname: Raimondi
authors.forename: W B
authors.initials: WB
authors.lastname: Mori
authors.forename: T C
authors.initials: TC
authors.lastname: Katsouleas
authors.forename: C
authors.initials: C
authors.lastname: Joshi
authors.forename: R H
authors.initials: RH
authors.lastname: Siemann