title: Elastic alpha-12C scattering and the 12C(alpha,gamma)16O E2 S factor.
abstract: Angular distributions of 12C(alpha,alpha)12C have been measured for E(alpha) = 2.6-8.2 MeV, at angles from 24 to 166, yielding 12 864 data points. R-matrix analysis of the ratios of elastic scattering yields a reduced width amplitude of gamma12 = 0.47 +/- 0.06 MeV(1/2) for the Ex = 6.917 MeV (2+) state in 16O(a = 5.5 fm). The dependence of the chi2 surface on the interaction radius a has been investigated and a deep minimum is found at a = 5.42(+0.16)(-0.27) fm. Using this value of gamma12, radiative alpha capture and 16N beta-delayed alpha-decay data, the S factor is calculated at E(c.m.) = 300 keV to be S(E2)(300) = 53(+13)(-18) keV b for destructive interference between the subthreshold resonance tail and the ground state E2 direct capture.
authors.affiliation: University of Notre Dame, Notre Dame, Indiana, USA.
authors.forename: P
authors.initials: P
authors.lastname: Tischhauser
authors.forename: R E
authors.initials: RE
authors.lastname: Azuma
authors.forename: L
authors.initials: L
authors.lastname: Buchmann
authors.forename: R
authors.initials: R
authors.lastname: Detwiler
authors.forename: U
authors.initials: U
authors.lastname: Giesen
authors.forename: J
authors.initials: J
authors.lastname: Görres
authors.forename: M
authors.initials: M
authors.lastname: Heil
authors.forename: J
authors.initials: J
authors.lastname: Hinnefeld
authors.forename: F
authors.initials: F
authors.lastname: Käppeler
authors.forename: J J
authors.initials: JJ
authors.lastname: Kolata
authors.forename: H
authors.initials: H
authors.lastname: Schatz
authors.forename: A
authors.initials: A
authors.lastname: Shotter
authors.forename: E
authors.initials: E
authors.lastname: Stech
authors.forename: S
authors.initials: S
authors.lastname: Vouzoukas
authors.forename: M
authors.initials: M
authors.lastname: Wiescher