Three-body correlations in electromagnetic dissociation of Borromean nuclei: The 6He case

• Published in: Nuclear physics. A Vol. 759; no. 1; pp. 23 - 42
• Main Authors: Chulkov, L.V., Simon, H., Thompson, I.J., Aumann, T., Borge, M.J.G., Elze, Th.W., Emling, H., Geissel, H., Grigorenko, L.V., Hellström, M., Jonson, B., Kratz, J.W.V., Kulessa, R., Markenroth, K., Meister, M., Münzenberg, G., Nickel, F., Nilsson, T., Nyman, G., Pribora, V., Richter, A., Riisager, K., Scheidenberger, C., Schrieder, G., Tengblad, O., Zhukov, M.V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2005
• Subjects: 6He; Coulomb excitation; Particle correlations; Unstable nuclei; 25.60.-t; 6He; Coulomb excitation; Particle correlations; Unstable nuclei; 25.70.De; 25.75.Gz; 27.20.+n
• ISSN: 0375-9474
• DOI: 10.1016/j.nuclphysa.2005.05.001

Dissociation of 6He on a lead target has been studied at 240 MeV/u. The four-momenta of the two neutrons in coincidence with α-particles have been measured and used to reconstruct the three-body energy and angular correlations in the final state. For the first time, three-body correlations were included in the analysis of the 6He dissociation data, and compared with calculations assuming a dipole mode for the electromagnetic dissociation. In addition, the experimental data have been analyzed using a series expansion of the final transition amplitude into hyperspherical functions, showing the importance of both nn and αn final-state interactions. It is shown that the dissociation process is governed by a transition of one neutron from the p-shell in the 6He ground state to the s-shell in the continuum further indicating that the role of the transition through an intermediate 5He( 3 / 2 − ) state is more important than expected.