| 1. |
- Andreyev, A. N., et al.
(författare)
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New microsecond isomers in Bi-189,Bi-190
- 2001
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 10:2, s. 129-133
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Tidskriftsartikel (refereegranskat)abstract
- New microsecond isomers in the neutron-deficient isotopes Bi-189g,Bi-190 have been identified after in-flight separation by the velocity filter SHIP. The evaporation residues were identified on the basis of delayed recoil-gamma /X-ray, recoil-gamma /X-ray-alpha and excitation function measurements. The systematics of the [pi 1i(13/2)]13/2(+) excited states in the odd-mass Bi nuclei is discussed.
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| 2. |
- Andreyev, A. N., et al.
(författare)
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The discovery of a prolate-oblate-spherical shape triple of spin 0(+) states in the atomic nucleus Pb-186
- 2001
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474 .- 1873-1554. ; 682, s. 482C-486C
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Tidskriftsartikel (refereegranskat)abstract
- Two excited J(pi)=0(+) states in Pb-186 populated in the a-decay of Po-190 have been identified through alpha -particle/conversion electron coincidences in an experiment at the velocity filter SHIP. The parent Po-190 nuclei have been produced in the Nd-142(Cr-52,4n)Po-190 complete fusion reaction, alpha -particle energies and branching ratios have been measured and hindrance factors were deduced. The observed states have been interpreted as the band heads of the known prolate and (yet unobserved) oblate rotational bands in Pb-186.
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| 3. |
- Joss, D. T., et al.
(författare)
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Identification of excited states in Os-167 and Os-168 : shape coexistence at extreme neutron deficiency
- 2001
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Ingår i: Nuclear Physics A. - : Elsevier. - 0375-9474 .- 1873-1554. ; 689:04-mar, s. 631-654
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the very neutron-deficient isotopes Os-167 and Os-168 have been observed using the reaction Sn-112(Ni-58, 2pxn). The JUROSPHERE gamma -ray spectrometer array was used in conjunction with the RITU gas-filled recoil separator to collect prompt gamma radiation in coincidence with recoils implanted in a silicon strip detector located at the focal plane of RITU. Using a selective recoil decay tagging technique it has been possible to unambiguously assign gamma -ray transitions to Os-167 and Os-168 through the characteristic a radioactivity of these nuclides. The high-spin structure of the bands is discussed in terms of quasiparticle configurations within the framework of the cranked shell model. The role of shape coexistence in Os-168 is examined with phenomenological three-band mixing calculations.
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| 4. |
- Joss, D. T., et al.
(författare)
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Strongly coupled bands in the neutron-deficient nucleus Re-167
- 2003
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 68:1
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the neutron-deficient nucleus Re-167 have been observed in a recoil-tagging experiment performed with the Jurosphere gamma-ray spectrometer in conjunction with the RITU gas-filled recoil separator. The low-spin yrast band, based on a proton h(11/2) orbital, comprises a strongly coupled band and exhibits significant signature splitting, indicative of a triaxial shape with gamma<0degrees. At higher spin the rotational alignment of a pair of i(13/2) neutrons induces a transition to an axial prolate shape resulting in a drastic reduction of the signature splitting. Two other strongly coupled bands have been established and their structures are discussed in terms of quasiparticle configurations.
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| 5. |
- Joss, D. T., et al.
(författare)
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Yrast spectroscopy in the neutron-deficient nucleus Os-169
- 2002
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Ingår i: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 66:5
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the neutron-deficient isotope Os-169 have been identified for the first time in an experiment using the Jurosphere gamma-ray spectrometer in conjunction with the Ritu gas-filled recoil separator. The problems associated with identifying neutron-deficient isotopes produced with low fusion cross sections against a high background of competing channels, including fission, have been overcome by using the recoil-decay tagging technique. The band structures observed in Os-169 are interpreted in the context of the systematics of neighboring nuclei and the predictions of cranked Woods-Saxon calculations. The systematics of the second (i(13/2))(2) neutron alignment in this region are discussed.
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| 6. |
- Nieminen, P., et al.
(författare)
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gamma-ray spectroscopy of Bi-191,Bi-193
- 2004
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:6, s. 064326-
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Tidskriftsartikel (refereegranskat)abstract
- Prompt and delayed gamma rays from Bi-191,Bi-193 have been identified using the recoil-decay tagging, isomer tagging, and recoil gating techniques, resulting in extensive level schemes for both nuclei. Excitation energies of the isomeric 13/2(+) states have been established and oblate strongly coupled bands built on them have been observed. The nearly spherical 9/2(-) ground-state bands appear to be crossed by more oblate-deformed low-lying structures. The properties of the bands feeding the 1/2(+) intruder states indicate some structural change between Bi-193 and Bi-191. The deformation associated with each of these states has been extracted from total Routhian surface calculations which also reveal the development of prolate minima with decreasing neutron number. B(M1)/B(E2) ratios have been measured for the observed strongly coupled bands in order to resolve the intrinsic excitations. The observed quasiparticle structures in Bi-193 and high-spin isomers both in Bi-193 and Bi-191 are interpreted based on the coupling of the odd proton to the even-even Pb core.
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| 7. |
- Van De Vel, K., et al.
(författare)
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In-beam gamma-ray spectroscopy of Po-190 : First observation of a low-lying prolate band in Po isotopes
- 2003
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 17:2, s. 167-171
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Tidskriftsartikel (refereegranskat)abstract
- Gamma rays from excited states of Po-190 have been observed using I the Jurosphere Ge-detector array coupled to the RITU gas-filled separator. They were associated with a collective band which from spin 4h onwards resembles the prolate rotational bands known in the isotones Pb-188 and Hg-186. This indicates that in Po-190 the prolate configuration becomes yrast above I = 2h. The experimental results are interpreted in a two-band mixing calculation and are in agreement with a-decay data and potential energy surface calculations.
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| 8. |
- Andreyev, A. N., et al.
(författare)
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In-beam and alpha-decay spectroscopy of Po-191 and evidence for triple shape coexistence at low energy in the daughter nucleus Pb-187
- 2002
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 66:1
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Tidskriftsartikel (refereegranskat)abstract
- Prompt gamma rays have been observed for the first time from the neutron-deficient nucleus Po-191 using the recoil-decay tagging technique at the RITU gas-filled separator. In addition improved alpha decay data have been measured for Po-191 and its daughter product Pb-187. The complementary gamma- and alpha-decay data point to the onset of oblate deformation in the light odd-mass Po nuclei by approaching the neutron midshell at N=104. The pattern of the favored and unfavored states observed on top of the 13/2(+) isomer in Po-191 indicates a change from the weak-coupling towards the strong-coupling scheme in Po-191m. In the daughter nucleus Pb-187, the 13/2(+) and 3/2(-) isomeric states become degenerate within the experimental accuracy. Evidence for triple shape coexistence at low energy has been found in the high-spin isomer in Pb-187. The results are supported by potential-energy surface calculations and by particle-plus-rotor calculations.
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| 9. |
- Bäck, Torbjörn, et al.
(författare)
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First observation of gamma-rays from the proton emitter Au-171
- 2003
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 16:4, s. 489-494
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-rays from the alpha- and proton-unstable nuclide Au-171 have been observed for the first time. The gamma-rays were correlated with both a proton- and an alpha-particle decay branch, confirming that the nucleus decays by alpha and proton emission from a single (11/2(-)) state. The measurement confirms the previously determined half-lives for these particle decays but the present values are of higher precision. In addition, a longer half-life than determined in previous work was measured for the proton-unstable tentative ground state. The results are discussed in relation to structures in neighbouring nuclei and compared with a Strutinsky-type TRS calculation.
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| 10. |
- Bäck, Torbjörn, et al.
(författare)
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Spectroscopy of the neutron-deficient nuclide Pt-171
- 2003
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 17:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- A number of previously unobserved gamma-rays emitted from the neutron-deficient nuclide Pt-171 have been identified using the recoil decay tagging technique. The level scheme has been updated using information from gamma-gamma coincidences and angular distribution measurements. To further confirm the assignments of the gamma-rays to Pt-171, the events were correlated with the alpha-decay of the daughter nucleus Os-167.
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