München 2006 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HK: Physik der Hadronen und Kerne

HK 4: Kernphysik/Spektroskopie

HK 4.1: Vortrag

Montag, 20. März 2006, 14:00–14:15, C

Single-particle structure of ⁷He* — •N. Ryezayeva¹, C. Bäumer², A. van den Berg³, L.V. Chulkov^4,5, D. Frekers², D. De Frenne⁶, P. Haefner², E. Jacobs⁶, H. Johanson⁴, Y. Kalmykov¹, A. Negret⁶, P. von Neumann-Cosel¹, L. Popescu⁶, S. Rakers², A. Richter¹, G. Schrieder¹, A. Shevchenko¹, H. Simon⁵, and H.J. Wörtche³ — ¹Institut für Kernphysik, TU Darmstadt, Germany — ²Institut für Kernphysik, Universität Münster, Germany — ³KVI Groningen, Netherlands — ⁴GSI Darmstadt, Germany — ⁵Kurchatov Institute, Moscow,Russia — ⁶Universiteit Gent, Belgium

The disappearance of the usual magic numbers in extremely neutron-rich nuclei implies a considerable modification in the spin-orbit interaction. Recent experiments give contradictory statements about a possible existence of the p_1/2 spin-orbit partner of the ⁷He ground state with a dominant p_3/2 single-particle character. In order to clarify this question a study of the ⁷Li(d,²He)⁷He reaction has been performed using a 171 MeV deuteron beam from the KVI cyclotron. A possible resonance at an excitation energy E_x ≃ 1.5 MeV with a width Γ ≃ 2.0 MeV is suggested by a decomposition of the spectrum using known resonances and quasifree charge-exchange contributions, taking into account the cluster structure of ⁷Li. Gamow-Teller strengths for transitions to the lowest states in ⁷He are in remarkable agreement with results from ab initio Quantum Monte Carlo calculations. The neutron spectroscopic factor S_n of the ⁷He ground state is extracted by a R-matrix analysis.

*Supported by the DFG through SFB 634.