Elastic alpha-12C scattering and the 12C(alpha,gamma)16O E2 S factor.
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.
Tischhauser
P
P
University of Notre Dame, Notre Dame, Indiana, USA.
Azuma
R E
RE
Buchmann
L
L
Detwiler
R
R
Giesen
U
U
Görres
J
J
Heil
M
M
Hinnefeld
J
J
Käppeler
F
F
Kolata
J J
JJ
Schatz
H
H
Shotter
A
A
Stech
E
E
Vouzoukas
S
S
Wiescher
M
M