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Physics Letters B 615 (2005) 167-174
$^{16}$O Coulomb dissociation: towards a new means to determine the $^{12}$C+$\alpha$ fusion rate in stars
F. Fleurot, A.M. Van den Berg, B. Davids, M.N. Harakeh, V.L. Kravchuk, H.W. Wilschut, J. Guillot1, H. Laurent1, A. Willis1, M. Assuncao2, J. Kiener2, A. Lefebvre2, N. De Séréville2, V. Tatischeff2

A feasibility study was made of an important aspect of the Coulomb-dissociation method, which has been proposed for the determination of the rate of the astrophysically important $^{12}C(\alpha, \gamma)^{16}O$ reaction. A crucial aspect is the disentanglement of nuclear and Coulomb interactions on one hand and the separation of dipole and quadrupole contributions on the other. As a first step the resonant breakup via two well-known 2$^+$ states of $^{16}O$ was measured. The differential cross section of $^{208}Pb(^{16}O, ^{16}O*)^{208}Pb$ and the angular correlations of the fragments $^{12}C$ and $\alpha$ in the center of mass were measured and compared to theoretical predictions calculated in DWBA and the coupled-channel method. The best agreement was found for the state at 11.52 MeV associated to a one-step excitation from the ground state, while the 9.84 MeV requires coupling to the first-excited 2$^+$ state and is not well described.
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
2 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
Physique/Physique Nucléaire Expérimentale