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arXiv · 0808.0264

Shape coexistence near the neutron number N=20: First identification of the E0 decay from the deformed 0^+_2 state in 30Mg

W. Schwerdtfeger·P. G. Thirolf·K. Wimmer·D. Habs·H. Mach·T. R. Rodriguez·V. Bildstein·J. L. Egido·L. M. Fraile·R. Gernhaeuser·R. Hertenberger·K. Heyde·P. Hoff·H. Huebel·U. Koester·T. Kroell·R. Kruecken·R. Lutter·T. Morgan·P. Ring
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Abstract

The 1789 keV level in 30Mg was identified as the first excited 0^+ state by measuring its E0 transition to the ground state. The measured small value of rho^2(E0,0^+_2 --> 0^+_1) = 5.7(14) x 10^-3 implies a very small mixing of competing configurations with largely different intrinsic quadrupole deformation near N=20. Axially symmetric Beyond-Mean-Field configuration mixing calculations identify the ground state of 30Mg to be based on neutron configurations below the N=20 shell closure, while the excited 0^+ state mainly consists of a two neutrons excitated into the nu1 f_{7/2} orbital. Using a two-level model, a mixing amplitude of 0.08(4) can be derived.

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W. Schwerdtfeger, P. G. Thirolf, K. Wimmer, D. Habs, H. Mach, T. R. Rodriguez, V. Bildstein, J. L. Egido, L. M. Fraile, R. Gernhaeuser, R. Hertenberger, K. Heyde, P. Hoff, H. Huebel, U. Koester, T. Kroell, R. Kruecken, R. Lutter, T. Morgan, P. Ring. 2008-08-02. Shape coexistence near the neutron number N=20: First identification of the E0 decay from the deformed 0^+_2 state in 30Mg. https://doi.org/10.1103/physrevlett.103.012501

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