Collective excitations of Ru-96 by means of (p, p 'gamma) experiments
Artikel i vetenskaplig tidskrift, 2015

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.


A. Hennig

T. Ahn

V. Anagnostatou

A. Blazhev

N. Cooper

V. Derya

M. Elvers

J. Endres

P. Goddard

Andreas Martin Heinz

Chalmers, 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 - Nuclear Physics

0556-2813 (ISSN) 1089-490X (eISSN)

Vol. 92