title: Direct measurement of the L/K ratio in (7)Be electron capture.
abstract: The ratio of L- to K-shell electron captures in light nuclei is particularly sensitive to electron overlap and exchange effects. Calculations of these effects in (7)Be disagree by more than 20%. We report a measurement of the L/K ratio in (7)Be, using a cryogenic microcalorimeter which clearly separates L- and K-shell captures. The obtained L/K ratio of 0.040(6) is less than half that of existing predictions for free (7)Be. The discrepancy is likely due to in-medium effects distorting the L-shell electron orbitals.
authors.affiliation: Physics Department, Wittenberg University, Springfield, Ohio 45501-0720, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Voytas
authors.forename: C
authors.initials: C
authors.lastname: Ternovan
authors.forename: M
authors.initials: M
authors.lastname: Galeazzi
authors.forename: D
authors.initials: D
authors.lastname: McCammon
authors.forename: J J
authors.initials: JJ
authors.lastname: Kolata
authors.forename: P
authors.initials: P
authors.lastname: Santi
authors.forename: D
authors.initials: D
authors.lastname: Peterson
authors.forename: V
authors.initials: V
authors.lastname: Guimarães
authors.forename: F D
authors.initials: FD
authors.lastname: Becchetti
authors.forename: M Y
authors.initials: MY
authors.lastname: Lee
authors.forename: T W
authors.initials: TW
authors.lastname: O'Donnell
authors.forename: D A
authors.initials: DA
authors.lastname: Roberts
authors.forename: S
authors.initials: S
authors.lastname: Shaheen