| 1. |
- Elvers, M., et al.
(författare)
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Investigation of octupole vibrational states in 150Nd via inelastic proton scattering (p,p 'gamma)
- 2011
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- Octupole vibrational states were studied in the nucleus (150)Nd via inelastic proton scattering with 10.9-MeV protons, which are an excellent probe to excite natural parity states. For the first time in (150)Nd, both the scattered protons and the gamma rays were detected in coincidence, giving the possibility to measure branching ratios in detail. Using the coincidence technique, the B(E1) ratios of the decaying transitions for 10 octupole vibrational states and other negative-parity states to the yrast band were determined and compared to the Alaga rule. The positive and negative-parity states revealed by this experiment are compared with interacting boson approximation calculations performed in the spdf boson space. The calculations are found to be in good agreement with the experimental data, for both positive and negative-parity states.
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| 2. |
- Hennig, A., et al.
(författare)
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Collective excitations of Ru-96 by means of (p, p 'gamma) experiments
- 2015
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 92:6
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Hennig, A., et al.
(författare)
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Mixed-symmetry octupole and hexadecapole excitations in N=52 isotones
- 2015
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2101-6275 .- 2100-014X. - 9782759817948 ; 93
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Konferensbidrag (refereegranskat)abstract
- In addition to the well-established quadrupole mixed-symmetry states, octupole and hexadecapole excitations with mixed-symmetry character have been recently proposed for the N = 52 isotones 92Zr and 94Mo. We performed two inelastic proton-scattering experiments to study this kind of excitations in the heaviest stable N = 52 isotone 96Ru. From the combined experimental data of both experiments absolute transition strengths were extracted.
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| 4. |
- Hennig, A., et al.
(författare)
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Mixed-symmetry octupole and hexadecapole excitations in the N=52 isotones
- 2014
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 90:5, s. Art. no. 051302-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Excitations with mixed proton-neutron symmetry have been previously observed in the N=52 isotones. Besides the well-established quadrupole mixed-symmetry states (MSS), octupole and hexadecapole MSS have been recently proposed for the nuclei Zr92 and Mo94. Purpose: The heaviest stable N=52 isotone Ru96 was investigated to study the evolution of octupole and hexadecapole MSS with increasing proton number. Methods: Two inelastic proton-scattering experiments on Ru96 were performed to extract branching ratios, multipole mixing ratios, and level lifetimes. From the combined data, absolute transition strengths were calculated. Results: Strong M1 transitions between the lowest-lying 3- and 4+ states were observed, providing evidence for a one-phonon mixed-symmetry character of the 32(-) and 42+ states. Conclusions: sdg-IBM-2 calculations were performed for Ru96. The results are in excellent agreement with the experimental data, pointing out a one-phonon hexadecapole mixed-symmetry character of the 42+ state. The 31-||M1||32(-) matrix element is found to scale with the 2s+||M1||2ms+ matrix element.
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| 5. |
- Hennig, A., et al.
(författare)
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Study of mixed-symmetry excitations in Ru-96 via inelastic proton-scattering
- 2015
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 580:1
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Konferensbidrag (refereegranskat)abstract
- Mixed-symmetry states of octupole (L = 3) and hexadecapole (L = 4) character have been recently proposed in the N = 52 isotones Zr-92 and Mo-94, based on strong M1 transitions to the lowest-lying 3(-) and 4(+) states, respectively. In order to investigate similar excitations in the heaviest stable N = 52 isotone Ru-96, two inelastic proton-scattering experiments have been performed at the Wright Nuclear Structure Laboratory (WNSL), Yale University, USA and the Institute for Nuclear Physics, University of Cologne, Germany. From the combined data of both experiments, absolute E-1, M-1, and E2 transition strengths were extracted, allowing for the identification of candidates for MS octupole and hexadecapole states. The structure of the low-lying 4(+) states is investigated by means of sdg-IBM-2 calculations.
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| 6. |
- Gürdal, G., et al.
(författare)
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Measurements of g(41+,22+) in 70,72,74 ,76Ge: Systematics of low-lying structures in 30≤Z≤40 and 30≤N≤50 nuclei
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 88:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The interplay between single-particle and collective excitations in the 30 ≤Z≤ 40 and 30 ≤N≤ 50 even-even isotopes has been examined in light of recent new measurements of magnetic moments of 41+, 22+, and 21+ states. Purpose: The g factors of the 41+ and 22+ states in the 72,74,76Ge isotopes have been measured for the first time and the g(21+) values have been remeasured. Methods: The transient field (TF) technique in inverse kinematics with a variety of targets has been applied, following Coulomb excitation of the relevant states. The data have been analyzed within the framework of the IBA-II model. Large-scale shell-model calculations have been performed within the p3/2,p1/2,f 5/2,g9/2 orbital space for both protons and neutrons with the JUN45 and JJ4B interactions. Results: The measured Ge g factors were compared to the g factors of the low-lying states of the neighboring Zn, Ge, Se, Kr, and Sr isotopes. The results were evaluated in the context of the systematics of g factors in the A∼80 region. Conclusions: The predictions based on the classic collective model and the interacting boson model IBA-II agree with the experimental results. No evidence for shell closure was found for neutrons at N=38 or N=40. © 2013 American Physical Society.
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| 7. |
- McCutchan, E.A., et al.
(författare)
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Shape coexistence and high-K states in 74Se populated following the β decay of 74Br
- 2013
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Ingår i: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 87:1
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in 74Se were populated following the ε/β + decay of 74Br, mainly from the J=K=4, 13.8-keV β-decaying isomer. Off-beam γ-ray spectroscopy was performed with the array of Clover HPGe detectors at WNSL Yale. Many new transitions were observed and rigorous spin assignments were made based on γ-γ angular correlations. The β-decay strength was found to proceed almost entirely to a few high-lying states near 4500 keV, which are consistent with deformed two-quasineutron high-K configurations. These doorway states then provide an effective tool for populating and identifying the lower prolate structures. Once categorized, the low-lying states of 74Se can be described as a set of near-spherical vibrational levels mixing strongly with a spectrum of prolate states which have an unperturbed bandhead near 1350 keV. © 2013 American Physical Society.
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| 8. |
- Werner, V., et al.
(författare)
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Evolution of collectivity near mid-shell from excited-state lifetime measurements in rare earth nuclei
- 2016
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Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 93:3
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Tidskriftsartikel (refereegranskat)abstract
- The B(E2) excitation strength of the first excited 2(+) state in even-even nuclei should directly correlate with the size of the valence space and maximize at mid-shell. A previously found saturation of B(E2) strengths in well-deformed rotors at mid-shell is tested through high-precision measurements of the lifetimes of the lowest-lying 2(+) states of the Hf-168 and W-174 rare earth isotopes. Measurements were performed using fast LaBr3 scintillation detectors. Combined with the recently remeasured B(E2; 2(1)(+) -> 0(1)(+)) values for Hf and W isotopes the new data remove discrepancies observed in the differentials of B(E2) values for these isotopes.
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