Bochum 2018 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 58: Structure and Dynamics of Nuclei X

HK 58.2: Vortrag

Freitag, 2. März 2018, 14:30–14:45, HZO 70

Quadrupole and octupole collectivity in doubly-magic ¹³²Sn — •D. Rosiak and P. Reiter for the MINIBALL IS551 and HIE-ISOLDE collaboration — IKP, Universität zu Köln

The vibrational first 2₁⁺ and 3₁⁻ states of the doubly-magic nucleus ¹³²Sn were excited via safe Coulomb excitation (CE) employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The ¹³²Sn ions were accelerated to an energy of 5.5 MeV/nucleon and impinged on a ²⁰⁶Pb target. Dexciting γ rays from the first excited states of the target and the projectile nucleus were recorded in coincidence with scattered particles. The optimized beam energy, the high-energy resolution and good efficiency of the HPGe spectrometer provide a beneficial combination to master the challenging measurement characterized by small CE cross sections and excitation energies above 4 MeV. The reduced transition strengths were determined for 0_g.s.⁺ → 2₁⁺, 0_g.s.⁺ → 3₁⁻, and 2₁⁺ → 3₁⁻ in ¹³²Sn. In the past first preliminary results for the B(E2;0_g.s.⁺ → 2₁⁺) value were obtained with an efficient BaF2 array at ORNL [1]. The results on excited collective states in ¹³²Sn provide crucial information on cross shell configurations that are expected to be dominated by a strong proton contribution. State-of-the-art large-scale shell model calculations and new mean field predictions are compared to the results. [1] R.L. Varner, et al., Eur. Phys. J. A 25, s01, 391 (2005). Supported by the German BMBF 05P12PKFNE and 05P15PKFN9.