| 1. |
- HILDINGSSON, L, et al.
(författare)
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HIGH-SPIN PHENOMENA IN OS-174
- 1992
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 545:4, s. 871-888
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Tidskriftsartikel (refereegranskat)abstract
- High-spin states of 174Os have been investigated by means of the (Nd(S, 4n)Os)-Nd-146-S-32-Os-174 reaction using the ESSA30 multidetector system. The decay is dominated by the ground-state positive-parity band, two negative-parity 4- and 5- bands and another band starting at spin 9. Deformed shell-model calculations have been carried out to interpret the observed band structures. The role of the strongly shape-driving, non-aligned, pi-h9/2 configuration in the low-spin region of the ground-state band is discussed. The first band crossing is interpreted as due to the nu-i13/2 alignment. The two lowest side-bands are understood in terms of coupling to octupole excitations.
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| 2. |
- Lerma, F., et al.
(författare)
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Superdeformed bands in Sr80-83, Y82-84, Zr-83,Zr-84 : Transition quadrupole moments, moments of inertia, and configuration assignments
- 2003
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 67:4, s. 044310-
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Tidskriftsartikel (refereegranskat)abstract
- Multiple superdeformed bands in the nuclei Sr80-83, Y82-84, and Zr-83,Zr-84 have been studied in a backed-target experiment, using the Gammasphere and the Microball 4pi detector arrays. For 15 bands in these nuclei, average transition quadrupole moments have been measured with high accuracy, using the Doppler-shift attenuation method. Among these are the newly observed superdeformed bands in Y-83,Y-84, which are isospectral with the bands in Sr-82,Sr-83. These isospectral bands have nearly identical transition quadrupole moments. Two of the bands in Sr-81 interact and cross transitions between them are observed. The present measurements place stringent conditions on configuration assignments for the bands obtained from two types of mean-field calculations, leading to a consistent understanding of the mass similar to80 superdeformed bands. The assignments for different bands arise from one or more nucleons occupying the N-0=5h(11/2) intruder orbital.
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| 3. |
- Rudolph, Dirk, et al.
(författare)
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Rotational Bands in the Doubly Magic Nucleus 56Ni
- 1999
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Ingår i: Physical Review Letters. - 1079-7114. ; 82:19, s. 3763-3766
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Tidskriftsartikel (refereegranskat)abstract
- Structures of the medium- to high-spin states in the doubly magic nucleus Ni-56 have been investigated using the reaction Si-28(Ar-36, 2 alpha) and the gamma-ray spectrometer Gammasphere in conjunction with the 4 pi charged-particle detector array Microball. Two well-deformed rotational bands have been identified. There is evidence that one of the bands, which is identical to a sequence in the odd-odd neighbor Cu-58, partially decays via proton emission into the ground state of Co-55. Predictions of extensive large-scale shell-model and cranked Hartree-Fock and Hartree-Fock-Bogolyubov calculations are compared with the experimental data.
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| 4. |
- Ban, Shufang, et al.
(författare)
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Nuclear symmetry energy in relativistic mean field theory
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 633:2-3, s. 231-236
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Tidskriftsartikel (refereegranskat)abstract
- The physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we confirm earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing epsilon(A) and an effective mean isovector potential strength K(A). A detailed analysis of the isospin dependence of these two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, similar to epsilon T-2, and, completely unexpectedly, the presence of a strong linear component similar to kappa T(T + 1 + epsilon/kappa) in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to E-sym similar to T(T + 1) at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.
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| 5. |
- Bhagwat, A., et al.
(författare)
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Investigation of band termination in the lower fp shell within the cranked relativistic mean field model
- 2013
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Ingår i: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP 2012). - : AIP. - 9780735411470 ; , s. 105-108
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Konferensbidrag (refereegranskat)abstract
- The excitation energy difference (ΔE) between the terminating states built on the f7/2 n and d3/2 -1f 7/2 n+1 configurations (here, 'n' denotes the number of valence particles outside the 40Ca core and the particle hole excitation across the magic gap 20 is of proton type) in the lower fp shell are studied systematically within the framework of the cranked relativistic mean field model. The ΔE thus defined, depends predominantly on the f 7/2 - d3/2 shell gap, and its evolution as a function of neutron - proton asymmetry. The latter, in turn, depends on the isoscalar - isovector balance in the spin - orbit potential. Therefore, a systematic investigation of the difference ΔE is expected to test quantitatively the predicted shell gaps as a function of isospin. We find that: 1) the conventional NL3 parameter set over estimates the ΔE values, implying that the said shell gap is over - estimated in this parametrization and 2) the largest deviation between the calculated and the experimental values of ΔE is obtained for the nucleus with the smallest asymmetry value in the set of nuclei considered, and that the deviation decreases with increasing asymmetry, indicating that the in RMF parametrization considered, the isoscalar - isovector balance in the spin - orbit potential requires improvement. We carry out a re - fit of the RMF parameters to attempt a remedy to these two problems. We find that in addition to the binding energies and charge radii, if a constraint is put on the f7/2 - d3/2 shell gap in the fit to the Lagrangian parameters, the overall agreement of ΔE with the experiment improves significantly, without disturbing the agreement already achieved for the bulk properties of the nuclei spanning the entire periodic table. At a finer level, however, it is found that the isoscalar - isovector balance in the spin orbit interaction is required to be improved further. A detailed work in this direction is in progress.
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| 6. |
- Cederwall, Bo, et al.
(författare)
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NEW FEATURES OF SUPERDEFORMED BANDS IN HG-194
- 1994
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 72:20, s. 3150-3153
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Tidskriftsartikel (refereegranskat)abstract
- Two new features of superdeformed (SD) bands in the A almost-equal-to 190 region emerge from a study of Hg-194 with the Gammasphere detector array. A decrease of the dynamic moment of inertia is observed for rotational frequencies HBARomega greater-than-or-equal-to 0.4 MeV, confirming long standing expectations based on mean field calculations with pairing. Evidence for a small staggering in the SD transition energies is also observed, suggesting the presence of terms with fourfold symmetry in the SD Hamiltonian.
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| 7. |
- Dobaczewski, J., et al.
(författare)
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Solution of universal nonrelativistic nuclear DFT equations in the Cartesian deformed harmonic-oscillator basis. (IX) HFODD (v3.06h) : A new version of the program
- 2021
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 48:10
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Tidskriftsartikel (refereegranskat)abstract
- We describe the new version (v3.06h) of the code HFODD that solves the universal nonrelativistic nuclear DFT Hartree-Fock or Hartree-Fock-Bogolyubov problem by using the Cartesian deformed harmonic-oscillator basis. In the new version, we implemented the following new features: (i) zero-range three- and four-body central terms, (ii) zero-range three-body gradient terms, (iii) zero-range tensor terms, (iv) zero-range isospin-breaking terms, (v) finite-range higher-order regularized terms, (vi) finite-range separable terms, (vii) zero-range two-body pairing terms, (viii) multi-quasiparticle blocking, (ix) Pfaffian overlaps, (x) particle-number and parity symmetry restoration, (xi) axialization, (xii) Wigner functions, (xiii) choice of the harmonic-oscillator basis, (xiv) fixed omega partitions, (xv) consistency formula between energy and fields, and we corrected several errors in the previous versions.
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| 8. |
- Llewellyn, R. D. O., et al.
(författare)
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Spectroscopy of proton-rich Zr-79 : Mirror energy differences in the highly-deformed fpg shell
- 2020
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 811
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Tidskriftsartikel (refereegranskat)abstract
- Energy differences between isobaric analogue states have been extracted for the A = 79, Zr-79/Y-79 mirror pair following their population via nucleon-knockout reactions from intermediate-energy rare-isotope beams. These are the heaviest nuclei where such measurements have been made to date. The deduced mirror energy differences (MED) are compared with predictions from a new density-functional based approach, incorporating isospin-breaking effects of both Coulomb and nuclear charge-symmetry breaking and configuration mixing.
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| 9. |
- Satula, W., et al.
(författare)
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A number projected model with generalized pairing interaction
- 2000
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Ingår i: Nuclear Physics A. - 0375-9474 .- 1873-1554. ; 676, s. 120-142
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Tidskriftsartikel (refereegranskat)abstract
- A mean-held model with a generalized pairing interaction that accounts for neutron-proton pairing is presented. Both the BCS as well as number-projected solutions of the model are presented. For the latter case the Lipkin-Nogami projection technique was extended to encompass the case of nonseparable proton-neutron systems. The influence of the projection on various pairing phases is discussed. In particular, it is shown that number-projection allows For mixing of different pairing phases but, simultanously, acts destructively on the proton-neutron correlations, The basic implications of proton-neutron pairing correlations on nuclear masses are discussed. It is shown that these correlations may provide a natural microscopic explanation of the Wigner energy lacking in mean-field models. A possible phase transition from isovector to isoscalar pairing condensate at high angular momenta is also discussed. In particular predictions for the dynamical moments of inertia for the superdeformed band in Ru-88 are given.
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| 10. |
- Satula, W., et al.
(författare)
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Cranking in isospace - Towards a consistent mean-field description of N = Z nuclei
- 2001
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Ingår i: Acta Physica Polonica B. - 0587-4254 .- 1509-5770. ; 32:9, s. 2441-2456
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Tidskriftsartikel (refereegranskat)abstract
- Excitation spectra DeltaE(T) of T = 0, 1, 2 states in even-even (e-e) and odd-odd (o-o) N = Z nuclei are analyzed within a mean-field based model involving isovector and isoscalar pairing interactions and the iso-cranking formalism applied to restore approximately isospin symmetry. It is shown that T = 0 states in o-o and T = 1 states in e-e nuclei correspond to two-quasiparticle, time-reversal symmetry breaking excitations since their angular momenta are I not equal 0. On the other hand the lowest T = 2 states in e-e and T = 1 states in o-o nuclei, which both are similar in structure to their even-even isobaric analogue states, are described as e-e type vacua excited (iso-cranked) in isospace. It appears that in all cases isoscalar pairing plays a crucial role in restoring the proper value of the inertia parameter in isospace i.e. DeltaE(T).
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