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Collective excitations of Ru-96 by means of (p, p 'gamma) experiments

A. Hennig ; T. Ahn ; V. Anagnostatou ; A. Blazhev ; N. Cooper ; V. Derya ; M. Elvers ; J. Endres ; P. Goddard ; Andreas Martin Heinz (Institutionen för fundamental fysik) ; R. O. Hughes ; G. Ilie ; M. N. Mineva ; P. Petkov ; S. G. Pickstone ; N. Pietralla ; D. Radeck ; T. J. Ross ; D. Savran ; M. Spieker ; V. Werner ; A. Zilges
Physical Review C (0556-2813). Vol. 92 (2015), 6,
[Artikel, refereegranskad vetenskaplig]

Background: One-phonon mixed-symmetry quadrupole excitations are a well-known feature of near-spherical, vibrational nuclei. Their interpretation as a fundamental building block of vibrational structures is supported by the identification of multiphonon states resulting from a coupling of fully-symmetric and mixed-symmetric quadrupole phonons. In addition, the observation of strong M1 transitions between low-lying 3(-) and 4(+) states has been interpreted as an evidence for one-phonon mixed-symmetry excitations of octupole and hexadecapole character. Purpose: The aim of the present study is to identify collective one-and two-phonon excitations in the heaviest stable N = 52 isotone Ru-96 based on a measurement of absolute M1, E1, and E2 transition strengths. Methods: Inelastic proton-scattering experiments have been performed at the Wright Nuclear Structure Laboratory (WNSL), Yale University, and the Institute for Nuclear Physics (IKP), University of Cologne. From the acquired proton-gamma and gamma gamma coincidence data we deduced spins of excited states, gamma-decay branching ratios, and multipole mixing ratios, as well as lifetimes of excited states via the Doppler-shift attenuation method (DSAM). Results: Based on the new experimental data on absolute transition strengths, we identified the 2(+) and 3(+) members of the two-phonon mixed-symmetry quintuplet (2(1,ms)(+) circle times 2(1,s)(+)). Furthermore, we observed strong M1 transitions between low-lying 3(-) and 4(+) states suggesting one-phonon symmetric andmixed-symmetric octupole and hexadecapole components in their wave functions, respectively. The experimental results are compared to sdg-IBM-2 and shell-model calculations. Conclusions: Both the sdg-IBM-2 and the shell-model calculations are able to describe key features of mixed-symmetry excitations of Ru-96. Moreover, they support the one-phonon mixed-symmetry hexadecapole assignment of the experimental 4(2)(+) state.

Denna post skapades 2016-01-20. Senast ändrad 2016-01-27.
CPL Pubid: 231010


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Institutionen för fundamental fysik (2005-2015)



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