Bochum 2018 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 24: Structure and Dynamics of Nuclei IV

HK 24.3: Vortrag

Dienstag, 27. Februar 2018, 17:15–17:30, HZO 70

Low-energy dipole response of the halo nuclei ^6,8He — •Christopher Lehr¹ and Thomas Aumann^1,2 for the NeuLAND-SAMURAI collaboration — ¹TU Darmstadt — ²GSI Helmholtzzentrum

The heaviest bound helium isotopes ⁶He and ⁸He are 2- and 4-neutron halo nuclei with a clear alpha plus 2n and 4n structure. The multi-neutron decay of ⁶He and ⁸He after heavy-ion induced electromagnetic excitation reactions has been measured kinematically complete to study the dipole response of these nuclei. An experiment was performed at the RIBF facility at the RIKEN Nishina Center in Japan. The combination of the neutron detectors NEBULA and NeuLAND at the SAMURAI setup and the high beam intensities available at RIBF made this measurement possible for the first time. The experimental method is based on the measurement of the differential cross section via the invariant-mass method, which allows to extract the dipole strength distribution dB(E1)/dE and the photo-absorption cross section. To induce electromagnetic excitation reactions of ⁶He and ⁸He a lead target was used. Additionally a series of targets with increasing Z was used to get precise information about the nuclear contribution to the cross section. This is especially important in the region of high excitation energy, where the electromagnetic excitation might not be dominant. The experimental setup and the method are explained. Besides this the first steps of the ongoing analysis are presented.

This work is supported by the DFG through grant no. SFB 1245, the GSI-TU Darmstadt cooperation and the BMBF project 05P15RDFN1.