| 1. |
- Bree, N, et al.
(författare)
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Shape Coexistence in the Neutron-Deficient Even-Even Hg182-188 Isotopes Studied via Coulomb Excitation.
- 2014
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Ingår i: Physical Review Letters. - 1079-7114. ; 112:16
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Tidskriftsartikel (refereegranskat)abstract
- Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85 MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.
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| 2. |
- Wrzosek-Lipska, K., et al.
(författare)
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Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes : Coulomb excitation of 182Hg, 184Hg, 186Hg and 188Hg
- 2019
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 55:8
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass 182-188 Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 01,2+, 21,2+ and 41+ states was observed in all nuclei under study. Reduced E2 matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.
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| 3. |
- Ketelhut, S., et al.
(författare)
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gamma-Ray Spectroscopy at the Limits : First Observation of Rotational Bands in Lr-255
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:21, s. 212501-
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Tidskriftsartikel (refereegranskat)abstract
- The rotational band structure of Lr-255 has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, Lr-255 is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2(-)[521] and 7/2(-)[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.
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| 4. |
- Parr, E., et al.
(författare)
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Single-particle states and parity doublets in odd- Z Ac 221 and Pa 225 from α -decay spectroscopy
- 2022
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Ingår i: Physical Review C. - 2469-9985. ; 105:3
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Tidskriftsartikel (refereegranskat)abstract
- Low-lying states in the odd-Z isotopes Ac13289221 and Pa13491225 have been studied using α-particle and αγ-coincidence spectroscopy in the Pa225→Ac221→Fr217 decay chain. Ground-state spin and parity assignments of Iπ = 5/2- are proposed for both Ac221 and Pa225, with the odd proton occupying the ω = 5/2 orbital of the quadrupole-octupole deformed shell model in both nuclei. In Ac221, excited states in the bands based on the ω = 5/2 and ω = 3/2 orbitals have been identified, including proposed parity-doublet states. The results suggest that reflection-asymmetric deformation of the ground state persists in the odd-A members of the isotope chains down to N = 132 for Ac and N = 134 for Pa, before reaching the transitional region at N = 130.
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| 5. |
- Petts, A., et al.
(författare)
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Lifetime measurements and coulomb excitation of light Hg nuclei
- 2009
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Ingår i: Capture Gamma-Ray Spectroscopy and Related Topics. - : American Institute of Physics (AIP). - 9780735406230 ; , s. 414-418
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Konferensbidrag (refereegranskat)abstract
- Two complementary experimental programs have taken place to investigate the origin and evolution of shape coexistence in the light mercury region. Recoil Distance Doppler-shift measurements were performed at the University of Jyväskylä utilizing the Köln plunger device in conjunction with the JUROGAM + RITU + GREAT setup. In addition, Coulomb excitation measurements of 184,186,188Hg were performed at REX-ISOLDE using the MINIBALL Ge-detector array. The results of the lifetime measurements of the yrast states up to Iπ = 10+ in 182Hg are reported. Preliminary analysis of the Coulomb excitation data is also discussed.
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| 6. |
- Bianco, L., et al.
(författare)
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Discovery of W-157 and Os-161
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 690:1, s. 15-18
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Tidskriftsartikel (refereegranskat)abstract
- The nuclides W-157 and Os-161 have been discovered ill reactions of Ni-58 ion beams with a Cd-106 target. The Os-161 alpha-decay energy and half-life were 6890 +/- 12 keV and 640 +/- 60 mu s. The daughter W-157 nuclei beta-decayed with a half-life of 275 +/- 40 ms, populating both low-lying alpha-decaying states in Ta-157, which is consistent with a 7/2(-) ground state in W-157. Fine structure observed in the alpha decay of Os-161 places the lowest excited state in W-157 with 1(pi) = 9/2(-) at 318 +/- 30 key. The branching ratio of 5.5(-2.2)(+3.1)% indicates that Os-161 also has a 7/2(-) ground state. Shell-model calculations analysing the effects of monopole shifts and a tensor force on the relative energies of 2f(7/2) and 1h(9/2) neutron states in N = 83 isotones are presented. (C) 2010 Elsevier B.V. All rights reserved.
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| 7. |
- Davis-Merry, T. R., et al.
(författare)
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Collective excitations in the transitional nuclei Re-163 and Re-165
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 91:3
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the neutron-deficient nuclei (163)(75) Re-88 and (165)(75) Re-90 were populated in the Cd-106(Ni-60, p2n gamma) and Mo-92(Kr-78, 3p2n gamma) fusion-evaporation reactions at bombarding energies of 270 and 380 MeV, respectively.. rays were detected at the target position using the JUROGAM spectrometer while recoiling ions were separated in-flight by the RITU gas-filled recoil separator and implanted in the GREAT spectrometer. The energy level schemes for Re-163 and Re-165 were identified using recoil-decay correlation techniques. At low spin, the yrast bands of these isotopes consist of signature partner bands based on a single pi h(11/2) quasiproton configuration. The bands display large energy splitting consistent with the soft triaxial shape typical of transitional nuclei above N = 82. The configurations of the excited states are proposed within the framework of the cranked shell model.
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| 8. |
- Gaffney, L. P., et al.
(författare)
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Collectivity in the light radon nuclei measured directly via Coulomb excitation
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 91:6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z = 82 and the neutron midshell at N = 104. Purpose: Evidence for shape coexistence has been inferred from a-decay measurements, laser spectroscopy, and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of Rn-202 and Rn-204 were studied by means of low-energy Coulomb excitation at the REX-ISOLDE in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first excited 2(1)(+) state was extracted for both Rn-202 and Rn-204, corresponding to B(E2; 2(1)(+) -> 0(1)(+)) = 29(-8)(+8) and 43(-12)(+17) W.u., respectively. Additionally, E2 matrix elements connecting the 2(1)(+) state with the 4(1)(+) and 2(2)(+) states were determined in Rn-202. No excited 0(+) states were observed in the current data set, possibly owing to a limited population of second-order processes at the currently available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced.
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| 9. |
- Joss, D. T., et al.
(författare)
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Evolving collective structures in the transitional nuclei W-162 and W-164
- 2016
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Ingår i: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 93:2
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the neutron-deficient nuclides(74)(162)W(88) and W-164(74)90 were investigated by using the gamma-ray spectrometer Jurogam. A change in structure is apparent from the first rotational alignments in W-162 and W-164, whose rotationally aligned bands are interpreted as nu(h(9/2))(2) and nu(i(13/2))(2) configurations, respectively. The level schemes have been extended using recoil (-decay) correlations with the observation of excited collective structures. Configuration assignments have been made on the basis of comparisons of the deduced aligned angular momentum, as a function of rotational frequency, with the predictions of the cranked shell model.
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| 10. |
- Leguillon, R., et al.
(författare)
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High-spin spectroscopy of Nd-140
- 2013
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:1
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Tidskriftsartikel (refereegranskat)abstract
- The population of the high-spin states in Nd-140 was investigated using the reaction Zr-96(Ca-48,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for Nd-140. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assuming a triaxial shape of the nucleus strongly support the existence of a stable triaxial shape at high spins in this mass region.
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| 11. |
- Procter, M. G., et al.
(författare)
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Anomalous transition strength in the proton-unbound nucleus (109)(53)I56
- 2011
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 704:3, s. 118-122
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Tidskriftsartikel (refereegranskat)abstract
- A lifetime measurement has been made for the first excited 11/2(+) state in the proton-unbound nucleus (109)(53)I56 using the recoil-distance Doppler-shift method in conjunction with recoil-proton tagging. The experimental reduced transition probability is considerably smaller than the prediction of theoretical shell-model calculations using the CD-Bonn nucleon-nucleon potential. The discrepancy between the theoretical and experimental reduced transition strengths in this work most likely arises from the inability of the current shell-model calculations to accurately account for the behavior of the unbound nuclear states.
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| 12. |
- Procter, M. G., et al.
(författare)
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Lifetime measurement in the proton-unbound nucleus 109I
- 2011
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Ingår i: AIP Conf. Proc.. - : AIP. - 9780735409835 ; , s. 105-110
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Konferensbidrag (refereegranskat)abstract
- The Recoil-Distance Doppler-shift method has been combined with Recoil-Decay Tagging for the first time to measure a lifetime in the proton-unbound nucleus 109I. The lifetime value was determined using the Differential Decay-Curve method in singles mode. The result has been compared to theoretical shell-model calculations in order to better understand the nature of unbound valence nucleons at the proton drip line.
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| 13. |
- Grahn, T., et al.
(författare)
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Excited states and reduced transition probabilities in Os-168
- 2016
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Ingår i: PHYSICAL REVIEW C. - : American Physical Society. - 2469-9985. ; 94:4
-
Tidskriftsartikel (refereegranskat)abstract
- The level scheme of the neutron-deficient nuclide Os-168 has been extended and mean lifetimes of excited states have been measured by the recoil distance Doppler-shift method using the JUROGAM gamma-ray spectrometer in conjunction with the IKP Koln plunger device. The 168Os. rays were measured in delayed coincidence with recoiling fusion-evaporation residues detected at the focal plane of the RITU gas-filled separator. The ratio of reduced transition probabilities B(E2; 4(1)(+)-> 2(1)(+))/B(E2; 2(1)(+)-> 0(1)(+)) is measured to be 0.34(18), which is very unusual for collective band structures and cannot be reproduced by interacting boson model (IBM-2) calculations based on the SkM* energy-density functional.
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| 14. |
- Lewis, M. C., et al.
(författare)
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Decay of a 19(-) isomeric state in Lu-156
- 2018
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:2
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Tidskriftsartikel (refereegranskat)abstract
- A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10(+) state in Lu-156 has been discovered. The Lu-156 nuclei were produced by bombarding isotopically enriched Cd-106 targets with beams of Ni-58 ions, separated in flight using the gas-filled separator RITU and their decays were measured using the GREAT spectrometer. Analysis of the main decay path that populates yrast states observed previously suggests a spin-parity assignment of 19(-) for the isomeric state, which is consistent with isomeric states identified in the N = 85 isotones. Comparison with other decay paths in Lu-156 indicates that the [pi h(11/)(2)(-1) circle times nu h(9/2)]10(+) state at the bottom of the yrast sequence is likely to be the a-decaying isomeric state, with the [pi h(11/)(2)(-1) circle times nu f(7/2)]9(+) state lying 62 keV above it. The relative ordering of the lowest-lying 9(+) and 10(+) states is inverted in Lu-156 compared with its odd-odd isotones.
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| 15. |
- Parr, E., et al.
(författare)
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Fine structure in the alpha decay of high-spin isomers in Lu-155 and Hf-156
- 2018
-
Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 98:2
-
Tidskriftsartikel (refereegranskat)abstract
- Fine structure in the a decay of high-spin isomers in Lu-155( 25/2(-)) and Hf-156(8(+))has been studied for the first time using alpha gamma- coincidence analysis. Three new a decays from Lu-155(25/2(-)) and two from Hf-156(8(+)) have been identified, populating seniority s > 1 states in the N = 82 nuclei Tm-151 and Yb-152, respectively. The reduced hindrance factors of the a decays support the previous configuration assignments of the populated states. This is the first observation of states with excitation energy greater than 1.5 MeV being populated following a decay in nuclei outside of the Pb-208 region.
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| 16. |
- Briselet, R., et al.
(författare)
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Production cross section and decay study of Es 243 and Md 249
- 2019
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Ingår i: Physical Review C. - 2469-9985. ; 99:2
-
Tidskriftsartikel (refereegranskat)abstract
- In the study of the odd-Z, even-N nuclei Es243 and Md249, performed at the University of Jyväskylä, the fusion-evaporation reactions Au197(Ca48,2n)Es243 and Tl203(Ca48,2n)Md249 have been used for the first time. Fusion-evaporation residues were selected and detected using a gas-filled separator coupled with its focal-plane spectrometer. For Es243, the recoil decay correlation analysis yielded a half-life of 24±3s and a maximum production cross section of 37±10nb. In the same way, a half-life of 26±1s, an α-branching ratio of 75±5%, and a maximum production cross section of 300±80nb were determined for Md249. The decay properties of Es245, the daughter of Md249, were also measured: an α-branching ratio of 54±7% and a half-life of 65±6s. Experimental cross sections were compared to the results of calculations performed using the kewpie2 statistical fusion-evaporation code.
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| 17. |
- Bäck, Torbjörn, et al.
(författare)
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Lifetime measurement of the first excited 2(+) state in (108)Te
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:4, s. 041306-
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of the first excited 2(+) state in the neutron deficient nuclide (108)Te has been measured for the first time, using a combined recoil decay tagging and recoil distance Doppler shift technique. The deduced reduced transition probability is B(E2;0(g.s.)(+) -> 2(+)) = 0.39(-0.04)(+0.05)e(2)b(2). Compared to previous experimental data on neutron deficient tellurium isotopes, the new data point constitutes a large step (six neutrons) toward the N = 50 shell closure. In contrast to what has earlier been reported for the light tin isotopes, our result for tellurium does not show any enhanced transition probability with respect to the theoretical predictions and the tellurium systematics including the new data is successfully reproduced by state-of-the-art shell model calculations.
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| 18. |
- Ertoprak, Aysegul, et al.
(författare)
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Evidence for octupole collectivity in 172Pt
- 2020
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Ingår i: European Physical Journal A. - : Springer. - 1434-6001 .- 1434-601X. ; 56:2
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the extremely neutron-deficient nucleus 172Pt were populated via 96Ru(78Kr,2p) and 92Mo(83Kr,3n) reactions. The level scheme has been extended up to an excitation energy of ~ 5 MeV and tentative spin-parity assignments up to Iπ = 18+. Linear polarization and angular distribution measurements were used to determine the electromagnetic E1 character of the dipole transitions connecting the positive-parity ground-state band with an excited side-band, firmly establishing it as a negative-parity band. The lowest member of this negative-parity structure was firmly assigned spin-parity 3-. In addition, we observed an E3 transition from this 3- state to the ground state, providing direct evidence for octupole collectivity in 172Pt. Large-scale shell model (LSSM) and total Routhian surface (TRS) calculations have been performed, supporting the interpretation of the 3- state as a collective octupole-vibrational state.
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| 19. |
- Herzáň, A., et al.
(författare)
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Detailed spectroscopy of Bi 193
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 92:4
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Tidskriftsartikel (refereegranskat)abstract
- An experiment aiming to study shape coexistence in Bi193 has been performed. Due to its transitional character, it has an exceptionally large number of structures identified close to the yrast line. Many new states have been found, significantly extending the previously known level scheme of Bi193, including several new rotational bands. The πi13/2 band was extended to Iπ=45/2+. The Iπ=31/2+ member of the πi13/2 band was found to de-excite also to a long-lived isomeric state. This isomeric state is located at 2350 keV and has a spin and parity of 29/2+. The half-life of the isomeric state was measured to be 85(3) μs and it decays via the emission of an 84 keV E2 transition. A level structure feeding this isomeric state was constructed. A low-energy, 49 keV transition has been identified to depopulate the (29/2-) isomeric state, which places it at an energy 2405 keV in the level scheme. This is the first time such a decay has been observed in the neutron-deficient Bi isotopes. A superdeformed band almost identical to that present in the neighboring isotope Bi191, based on the 1/2[651] Nilsson orbital, has also been identified.
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| 20. |
- Hodge, D., et al.
(författare)
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Identification of a dipole band above the Iπ=31/2- isomeric state in Pb 189
- 2015
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 92:5
-
Tidskriftsartikel (refereegranskat)abstract
- A dipole band of six transitions built upon a firmly established Iπ=31/2- isomeric state has been identified in Pb189 using recoil-isomer tagging. This is the lightest odd-mass Pb nucleus in which a dipole band is known. The dipole nature of the new transitions has been confirmed through angular-intensity arguments. The evolution of the excitation energy and the aligned-angular momentum of the states in the new dipole band are compared with those of dipole bands in heavier, odd-mass lead isotopes. This comparison suggests that the new band in Pb189 is based upon a π[s1/2-2h9/2i13/2]11- - ν[i13/2+-1]13/2+ configuration. However, the increased aligned-angular momentum in Pb189 may suggest evidence for a reduced repulsive proton/neutron-hole interaction compared to dipole bands in the heavier mass isotopes.
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| 21. |
- Hornillos, M. B. G., et al.
(författare)
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gamma-ray spectroscopy approaching the limits of existence of atomic nuclei : A study of the excited states of Pt-168 and Pt-169
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:6
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the N=90 and N=91 Pt nuclei have been investigated using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. These nuclei were populated via the reactions Mo-92(Kr-78,2n) and Mo-94(Kr-78,3n) at 335 and 348 MeV, respectively. The recoil-decay tagging technique has been used to correlate prompt gamma radiation with the characteristic alpha decays of Pt-168 and Pt-169. A gamma-gamma analysis has allowed a level scheme for Pt-168 to be reported for the first time and the level scheme for Pt-169 to be extended. The excitation energies of the proposed positive-parity yrast states of Pt-168 are compared with calculations based on the interacting boson model and found to be in excellent agreement. These data show a continuation of the trend toward vibrational nuclei as the N=82 shell gap is approached. In addition, new excited states constituting two decay paths have been discovered in Pt-169. .
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| 22. |
- Jakobsson, U., et al.
(författare)
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Prompt and delayed spectroscopy of At-199
- 2010
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 82:4, s. 044302-
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Tidskriftsartikel (refereegranskat)abstract
- The neutron-deficient nucleus At-199 has been studied through gamma-ray and electron spectroscopy, using the recoil-decay tagging technique. Two experiments were conducted, using a gas-filled recoil separator with a focal-plane spectrometer alone and together with a germanium-detector array at the target position. The resulting level scheme for 199At includes a new isomer with a half-life of 0.80(5) mu s and a spin and parity of (29/2(+)). The 13/2(+) isomer, which de-excites via an M2 transition to the 9/2 ground state, was measured to have a half-life of 70(20) ns. Our earlier version of the level scheme for At-197 has been updated as well.
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| 23. |
- Kesteloot, N., et al.
(författare)
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Deformation and mixing of coexisting shapes in neutron-deficient polonium isotopes
- 2015
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:5
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Tidskriftsartikel (refereegranskat)abstract
- Coulomb-excitation experiments are performed with postaccelerated beams of neutron-deficient Po-196,Po-198,Po-200,Po-202 isotopes at the REX-ISOLDE facility. A set of matrix elements, coupling the low-lying states in these isotopes, is extracted. In the two heaviest isotopes, Po-196,Po-198, the transitional and diagonal matrix elements of the 2(1)(+) state are determined. In Po-196,Po-198 multistep Coulomb excitation is observed, populating the 4(1)(+), 0(2)(+), and 2(2)(+) states. The experimental results are compared to the results from the measurement of mean-square charge radii in polonium isotopes, confirming the onset of deformation from Po-196 onwards. Three model descriptions are used to compare to the data. Calculations with the beyond-mean-field model, the interacting boson model, and the general Bohr Hamiltonian model show partial agreement with the experimental data. Finally, calculations with a phenomenological two-level mixing model hint at the mixing of a spherical structure with a weakly deformed rotational structure.
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| 24. |
- O'Donnell, D., et al.
(författare)
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First observation of excited states in Hg-175(95)
- 2009
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 79:5, s. 051304-
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Tidskriftsartikel (refereegranskat)abstract
- Excited states of the neutron-deficient nucleus Hg-175, populated using fusion-evaporation reactions, are reported for the first time. The spin and parity of the ground state has been determined to be I-pi=7/2(-) through measurements of the alpha decay to the daughter nucleus Pt-171. A structure based on an isomeric state [T-1/2=0.34(3) mu s] with I-pi=13/2(+) and its decay path to the ground state have been established. The observed structures are interpreted in terms of single-particle configurations, and the trends of coexisting shapes in neighboring nuclei are discussed.
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| 25. |
- Peura, P., et al.
(författare)
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Quasiparticle alignments and alpha-decay fine structure of Pt-175
- 2014
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 89:2, s. 024316-
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Tidskriftsartikel (refereegranskat)abstract
- Excited states and decay properties of Pt-175 have been investigated using the Mo-92(Sr-86, 2pn) fusion-evaporation reaction. The JUROGAM I gamma-ray spectrometer and the GREAT spectrometer were used in conjunction with the gas-filled recoil separator RITU for the measurement of the radiation at the target and focal plane positions, respectively. Two new band structures, assigned to be based on the I-pi = (7/2(-)) ground state in Pt-175, have been established and the known yrast band has been extended up to I-pi = (49/2(+)). Rotational properties of the excited states in Pt-175 have been investigated within the cranked shell-model formalism. The low-frequency changes in the alignments of the positive-and negative-parity bands are interpreted as a sign of proton-pair excitations in the rotating core. Furthermore, the alpha-decay measurements reveal a candidate for a fourth alpha-decay branch in Pt-175, feeding a non-yrast state in Os-171.
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