12C(6Li, d)16O at E(Li) = 90 MeV

Abstract

The 12C(6Li, d)16O reaction has been studied at E(6Li) = 90.2 MeV with a magnetic spectrometer. Spectra up to Ex [approximate] 30 MeV in 16O have been obtained and decay line widths, [Gamma]c.m., have been extracted for broad levels. Known [alpha]-cluster states (J[pi] = 2+, Ex = 6.9 MeV; J[pi] = 4+, Ex = 10.35 MeV) are preferentially populated exhibit sharply forward peaked angular distributions in contrast with (6Li, d) data obtained at lower bombarding energies. These features are well reproduced by reaction calculations assuming direct alpha-particle transfer provided one utilizes realistic optical model, target, and projectile wave functions. Alpha spectroscopic factors and reduced alpha widths have been extracted for levels Ex J[pi] = 1- levels of astrophysical interest. The results are compared with other recent measurements and theoretical calculations. There is generally at least qualitative agreement (within x 2) between the various experiments and theories. The analysis indicates a non-negligible alpha width for the J[pi] = 1- level at Ex = 7.1 MeV in 16O (which determines the 12C --> 16O stellar helium burning rate) with 0.3 [alpha]2 (7.1 MeV)/[theta][alpha]2 (9.6MeV) [alpha]2 (7.1 MeV)/ [theta][alpha]2 (6.9 MeV) < 0.4.