| 1. |
- Kelsall, N. S., et al.
(författare)
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Testing mean-field models near the N=Z line : gamma-ray spectroscopy of the T-z=1/2 nucleus Kr-73
- 2002
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 65:4
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in the N=Z+1 nucleus Kr-73 have been investigated using the Ca-40(Ar-36,2pn) and Ca-40(Ca-40,alpha2pn) reactions at 145 and 160 MeV, respectively. gamma rays were detected using the Gammasphere array and events were recorded in coincidence with charged-particle and neutron detectors. The three previously observed bands were extended to high spin, and a new unfavored positive-parity band has been observed. The alignment characteristics and decay properties of the bands are all consistent with large-deformation prolate rotation, with no clear evidence for oblate bands or shape coexistence. This is quite different from neighboring Kr-72,Kr-74, indicating a strong shape-stabilizing role for the valence neutron. The experimental results are compared to extended total Routhian surface, cranked Nilsson Strutinsky, and cranked relativistic mean-field calculations. The results suggest that the paired calculations lack some important physics. Neutron-proton correlations may be the missing ingredient. There is also evidence for an unusual band crossing in the negative-parity bands, which may indicate the presence of T=0 pairing correlations. At high spin all the models can reproduce the experimental data.
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| 2. |
- Kelsall, NS, et al.
(författare)
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High-spin structure of N similar or equal to Z nuclei around the A=72 region
- 2004
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Ingår i: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001. ; 20:1, s. 131-132
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states have been studied in Kr-72 and Br-72 using the Ca-40 + Ca-40 and Ar-36 + Ca-40 reactions at 164 and 145 MeV, respectively. The properties and configurations of the high-spin bands observed have been interpreted using impaired cranked Nilssou-Strutinsky (CNS), and for Kr-72, paired cranked relativistic Hartree-Bogoliubov (CRHB) calculations. In Kr-72 a new band has been identified that has the properties expected for the doubly aligned S-band configuration. In Br-72 the previously known bands have been extended to higher spin. This has lead to a re-interpretation of the configurations.
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| 3. |
- Kelsall, N.S., et al.
(författare)
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High-spin studies of N ~ Z nuclei in the mass 70 region
- 2003
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Ingår i: AIP Conference Proceedings. - 0094-243X .- 1551-7616. ; :656, s. 261-268
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Konferensbidrag (refereegranskat)abstract
- High-spin states have been studied in 72,73Kr using 40Ca+40Ca and 36Ar+40Ca reactions at 160, 164 and 145 MeV respectively. The properties and configurations of the bands observed are interpreted with the aid of unpaired cranked Nilsson-Strutinsky/ cranked relativistic mean-field calculations and paired total routhian surface and cranked relativistic Hartree-Bogoliubov calculations. In 73Kr the three previously known structures have been extended to a spin of ~30[h-bar] and a fourth structure, which is believed to be the signature partner to the g9/2 band, has been identified. The negative parity bands show evidence for an unusual type of band crossing. It is currently unclear whether this is a consequence of T=0 n-p pairing. At the highest spins the unpaired calculations can reproduce the observed data, suggesting that there is little evidence for pairing correlations in this spin regime. In 72Kr a new band has been identified that has the properties expected from the missing doubly aligned S-band configuration. The properties of this band can be reproduced by the unpaired CNS/ CRMF calculations, again suggesting that the structure has little pairing. However, paired calculations appear to be necessary to reproduce the properties of the previously known structure in this nucleus. The 72Kr results are also compared with projected shell model calculations. ©2003 American Institute of Physics
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| 4. |
- O'Leary, C. D., et al.
(författare)
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Evidence for isovector neutron-proton pairing from high-spin states in N = Z 74Rb
- 2003
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Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 67:2, s. 213011-213015
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states in the odd-odd N = Z nucleus 3774Rb37 were studied using the 40Ca(40Ca,αnp) reaction. A previously observed odd-spin T = 0 band has been extended to Iπ = (31+) and an even-spin T = 0 band has been observed for the first time to Iπ = (22+); both have a π(g9/2)⊗ν(g9/2) structure. A strongly coupled low-spin T = 0, K = 3 band has been interpreted as being based upon a π[312]3/2 ⊗ ν[312]3/2 configuration. Cranked relativistic Hartree-Bogoliubov calculations, which are corrected for the t = 1 np-pair field by restoring isospin symmetry, reproduce the observed spectrum. These new results provide evidence for the existence of an isovector pair field that contains a neutron-proton component with the proper strength for ensuring isospin conservation.
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| 5. |
- Plettner, C., et al.
(författare)
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Very high rotational frequencies and band termination in 73Br
- 2000
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Ingår i: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:1, s. 143131-143136
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Tidskriftsartikel (refereegranskat)abstract
- Rotational bands in 73Br have been investigated up to spins of I = 65/2 using the EUROBALL III spectrometer. One of the negative-parity bands displays the highest rotational frequency ℏω= 1.85 MeV reported to date in nuclei with A ≥ 25. At high frequencies, the experimental J(2) dynamic moment of inertia for all bands decreases to very low values, J(2) ≤ 10ℏ2 MeV-1. The bands are described in the configuration-dependent cranked Nilsson-Strutinsky model. The calculations indicate that one of the negative-parity bands is observed up to its terminating single-particle state at spin 63/2. This result establishes the first band termination in the A ≈ 70 mass region.
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