ABSTRACT Three different rotational bands have been observed to high spin in 75Rb using Gammasphe... more ABSTRACT Three different rotational bands have been observed to high spin in 75Rb using Gammasphere. The structures are similar, but not identical to those found in the neighboring Tz=1/2 nucleus 73Kr. Conventional total Routhian surface (TRS) calculations with T=1 pairing are able to reproduce the rotational bands in 75Rb with extreme accuracy, but they completely fail in reproducing the spectra and decay pattern of the negative parity bands in 73Kr. Simple qualitative arguments are put forward to show that the decay pattern observed in the negative parity bands in 73Kr can be accounted for by means of T=0 pair correlations. To further corroborate this scenario, deformation, and pairing self-consistent TRS calculations, including schematic T=1 and T=0 pairing, are performed for the first time indicating the onset of dynamical T=0 pair-correlations at high angular momenta.
... for the first time. obtained a satisfactory agreement for most of the structures. 3.1. Intrrr... more ... for the first time. obtained a satisfactory agreement for most of the structures. 3.1. Intrrrdrr hrrnds in I"'. lo', ' lo . ' ' I Cd nuclei The formation of intruder bands for Cd nuclei is suggested to be associated with 2p-4h excitations across the Z = 50 shell gap [39]. ...
A brief reminder is given of the evidence for the existence of octupole correlations in the super... more A brief reminder is given of the evidence for the existence of octupole correlations in the superdeformed shape of 193Hg. It is pointed out that comparison of the data on the superdeformed bands in 19Hg with Cranked Shell Model calculations gives firm assignments to the signatures and parities of these bands. The spin assignments obtained are in agreement with the
We report on the development of a new theoretical tool that allows for isospin projection of Slat... more We report on the development of a new theoretical tool that allows for isospin projection of Slater determinants and we present its first applications. In particular, we determine the isospin mixing in ground states of N = Z nuclei and discuss its dependence on the size of the harmonic-oscillator basis used in the calculations. We also discuss the unphysical contribution to the isospin mixing caused by the spurious isospin-symmetry breaking inherent to the mean-field approach. We show that these contributions may be as large as 30% of the value of the isospin-mixing parameter.
Nuclear pairing is an intrinsic phenomenon predominantly related to the attractiveness of the sho... more Nuclear pairing is an intrinsic phenomenon predominantly related to the attractiveness of the short-range part of the effective nuclear interaction at the Fermi energy. Since in most nuclei proton and neutron Fermi energies lie far apart, in most applications it is enough to consider only isovector pp—and nn— (t = 1,t z = ± 1) correlations. However, both charge independence of the nuclear force as well as stronger, on the average, attractivness of the isoscalar (t=0) interaction do suggest that proton-neutron (pn—)type pairing may be of importance in N~Z nuclei and indeed standard mean-field calculations seem to systematically underbind N=Z nuclei. Interestingly, the isoscalar (t=0) pn—pairing can provide locally [i.e. for N~Z] an extra binding -the so called Wigner energy -offering a simple and intuitive microscopic explanation to this problem [1, 2].
The spin-orbit (SO) interaction, emerging naturally from the Relativistic Mean Field (RMF) theory... more The spin-orbit (SO) interaction, emerging naturally from the Relativistic Mean Field (RMF) theory is examined critically in the light of the recently measured excitation energy differences between the terminating states built on two different configurations for nuclei belonging to the lower pf shell. The calculations are carried out using the cranked RMF framework. To further probe the iso-vector dependence of the spin-orbit potential, the energy spacing between the g_{7/2} and h_{11/2} states in the Sb-chain is compared to experiment. It is found that the calculation at the quantitative level deviates strongly from the experiment. In particular the balance of the iso-scalar and iso-vector strengths of the effective one body SO potential indicates that additional terms like tensor couplings may be needed to account for the experimental data.
The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged... more The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged-particle detector, has made possible a new class of nuclear lifetime measurement. For the first time differential lifetime measurements free from common systematic errors for over 15 different nuclei ( >30 rotational bands in various isotopes of Ce, Pr, Nd, Pm, and Sm) have been extracted at high spin within a single experiment. This comprehensive study establishes the effective single-particle transition quadrupole moments in the A approximately 135 light rare-earth region. Detailed comparisons are made with theoretical calculations using the self-consistent cranked mean-field theory which convincingly demonstrates the validity of the additivity of single-particle quadrupole moments in this mass region.
... 5.7.7. Example: An z proton bands in Sb nuclei Rotational bands have been observed quite some... more ... 5.7.7. Example: An z proton bands in Sb nuclei Rotational bands have been observed quite some time ago in the Sn isotopes [34,35] and can be associated with a twoparticletwohole excitation across the Z = 50 shell gap [34,36]. ...
ABSTRACT Three different rotational bands have been observed to high spin in 75Rb using Gammasphe... more ABSTRACT Three different rotational bands have been observed to high spin in 75Rb using Gammasphere. The structures are similar, but not identical to those found in the neighboring Tz=1/2 nucleus 73Kr. Conventional total Routhian surface (TRS) calculations with T=1 pairing are able to reproduce the rotational bands in 75Rb with extreme accuracy, but they completely fail in reproducing the spectra and decay pattern of the negative parity bands in 73Kr. Simple qualitative arguments are put forward to show that the decay pattern observed in the negative parity bands in 73Kr can be accounted for by means of T=0 pair correlations. To further corroborate this scenario, deformation, and pairing self-consistent TRS calculations, including schematic T=1 and T=0 pairing, are performed for the first time indicating the onset of dynamical T=0 pair-correlations at high angular momenta.
... for the first time. obtained a satisfactory agreement for most of the structures. 3.1. Intrrr... more ... for the first time. obtained a satisfactory agreement for most of the structures. 3.1. Intrrrdrr hrrnds in I"'. lo', ' lo . ' ' I Cd nuclei The formation of intruder bands for Cd nuclei is suggested to be associated with 2p-4h excitations across the Z = 50 shell gap [39]. ...
A brief reminder is given of the evidence for the existence of octupole correlations in the super... more A brief reminder is given of the evidence for the existence of octupole correlations in the superdeformed shape of 193Hg. It is pointed out that comparison of the data on the superdeformed bands in 19Hg with Cranked Shell Model calculations gives firm assignments to the signatures and parities of these bands. The spin assignments obtained are in agreement with the
We report on the development of a new theoretical tool that allows for isospin projection of Slat... more We report on the development of a new theoretical tool that allows for isospin projection of Slater determinants and we present its first applications. In particular, we determine the isospin mixing in ground states of N = Z nuclei and discuss its dependence on the size of the harmonic-oscillator basis used in the calculations. We also discuss the unphysical contribution to the isospin mixing caused by the spurious isospin-symmetry breaking inherent to the mean-field approach. We show that these contributions may be as large as 30% of the value of the isospin-mixing parameter.
Nuclear pairing is an intrinsic phenomenon predominantly related to the attractiveness of the sho... more Nuclear pairing is an intrinsic phenomenon predominantly related to the attractiveness of the short-range part of the effective nuclear interaction at the Fermi energy. Since in most nuclei proton and neutron Fermi energies lie far apart, in most applications it is enough to consider only isovector pp—and nn— (t = 1,t z = ± 1) correlations. However, both charge independence of the nuclear force as well as stronger, on the average, attractivness of the isoscalar (t=0) interaction do suggest that proton-neutron (pn—)type pairing may be of importance in N~Z nuclei and indeed standard mean-field calculations seem to systematically underbind N=Z nuclei. Interestingly, the isoscalar (t=0) pn—pairing can provide locally [i.e. for N~Z] an extra binding -the so called Wigner energy -offering a simple and intuitive microscopic explanation to this problem [1, 2].
The spin-orbit (SO) interaction, emerging naturally from the Relativistic Mean Field (RMF) theory... more The spin-orbit (SO) interaction, emerging naturally from the Relativistic Mean Field (RMF) theory is examined critically in the light of the recently measured excitation energy differences between the terminating states built on two different configurations for nuclei belonging to the lower pf shell. The calculations are carried out using the cranked RMF framework. To further probe the iso-vector dependence of the spin-orbit potential, the energy spacing between the g_{7/2} and h_{11/2} states in the Sb-chain is compared to experiment. It is found that the calculation at the quantitative level deviates strongly from the experiment. In particular the balance of the iso-scalar and iso-vector strengths of the effective one body SO potential indicates that additional terms like tensor couplings may be needed to account for the experimental data.
The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged... more The latest generation gamma-ray detection system, GAMMASPHERE, coupled with the Microball charged-particle detector, has made possible a new class of nuclear lifetime measurement. For the first time differential lifetime measurements free from common systematic errors for over 15 different nuclei ( >30 rotational bands in various isotopes of Ce, Pr, Nd, Pm, and Sm) have been extracted at high spin within a single experiment. This comprehensive study establishes the effective single-particle transition quadrupole moments in the A approximately 135 light rare-earth region. Detailed comparisons are made with theoretical calculations using the self-consistent cranked mean-field theory which convincingly demonstrates the validity of the additivity of single-particle quadrupole moments in this mass region.
... 5.7.7. Example: An z proton bands in Sb nuclei Rotational bands have been observed quite some... more ... 5.7.7. Example: An z proton bands in Sb nuclei Rotational bands have been observed quite some time ago in the Sn isotopes [34,35] and can be associated with a twoparticletwohole excitation across the Z = 50 shell gap [34,36]. ...
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Papers by W. Satula