Darmstadt 2016 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 13: Structure and Dynamics of Nuclei IV

HK 13.7: Vortrag

Montag, 14. März 2016, 18:15–18:30, S1/01 A04

Lifetime measurements in self-conjugate nuclei ⁴⁴Ti, ⁴⁸Cr and ⁵²Fe — •K. Arnswald, P. Reiter, B. Birkenbach, A. Blazhev, T. Braunroth, A. Dewald, C. Fransen, B. Fu, A. Hennig, R. Hirsch, L. Lewandowski, J. Litzinger, C. Müller-Gatermann, D. Rosiak, N. Saed-Samii, D. Schneiders, M. Seidlitz, B. Siebeck, T. Steinbach, A. Vogt, K. Wolf, and K.O. Zell — Institut für Kernphysik, Universität zu Köln

Reduced transition strengths expressed with B(E2) values are sensitive signatures to describe collective excitations of atomic nuclei and are indispensable to understand nuclear shell structures. Along the N=Z line in the 1f_7/2 shell they provide stringent tests of recent shell-model interactions. So far, B(E2, 2₁⁺→ 0_g.s.⁺) values for the self-conjugate ₂₂⁴⁴Ti, ₂₄⁴⁸Cr, ₂₆⁵²Fe isotopes are known only with considerable errors. Recoil Distance Doppler-Shift (RDDS) experiments were performed employing the Cologne coincidence plunger device to measure lifetimes with high precision in order to deduce model-independent B(E2) values. Excited states in the nuclei of interest were populated with fusion-evaporation reactions. γ rays were detected by an array of 12 HPGe detectors. Precise B(E2, 2₁⁺→ 0_g.s.⁺) values are measured to be 204₋₁₄⁺¹⁶  e²fm⁴, 262 ± 3  e²fm⁴, and 269± 8  e²fm⁴ for ⁴⁴Ti, ⁴⁸Cr, and ⁵²Fe, respectively. The results are compared to recent shell-model calculations on the basis of GX1A interaction [1]. While the excitation energies are reproduced quite well, the B(E2) values show considerable differences.

[1] M. Honma et al. Phys. Rev. C 69, 034335 (2004)