Bochum 1998 – scientific programme
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HK: Hadronen und Kerne
HK 53: Nuclear Astrophysics IV
HK 53.5: Talk
Wednesday, March 18, 1998, 15:15–15:30, G
E1-E2 interference in the Coulomb dissociation of 7Li∗ — •S. Typel and H. H. Wolter — Sektion Physik, Universität München, Am Coulombwall 1, D-85748 Garching
The break-up of 7Li into α and 3H can be considered as a test case for the Coulomb dissociation method to determine the astrophysical S-factor of the inverse radiative capture reaction 3H(α,γ)7Li. We calculate triple differential cross sections for the distribution of the break-up fragments in first-order semiclassical theory. The 7Li nucleus is described in a simple α-3H cluster model which predicts a S-factor, dominated by electric dipole transitions to the ground and first excited state, in accordance with direct measurements [1]. The asymmetry in the fragment distribution observed in a recent experiment with 42 MeV 7Li [2] for highly charged targets can be explained by an interference of E1 and E2 contributions in the Coulomb break-up. Here, in contrast to the capture reaction, only the ground state of 7Li is involved and E2 contributions are enhanced due to the large flux of the equivalent quadrupole photons.
∗ supported by GSI, Darmstadt, contract LMWolT.
[1] C. R. Brune, R. W. Kavanagh, and C. Rolfs, Phys. Rev. C50, 2205 (1994)
[2] H. Utsunomiya et al., Phys. Lett. B, in press