1. |
- Afanasjev, A. V., et al.
(author)
-
Comparative study of superdeformed and highly deformed bands in the [Formula Presented] mass region
- 1999
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 59:6, s. 3166-3171
-
Journal article (peer-reviewed)abstract
- Superdeformed and highly deformed rotational bands in the [Formula Presented] mass region are studied within cranked relativistic mean field theory and the configuration-dependent cranked Nilsson-Strutinsky approach. Both approaches describe the experimental data well. Low values of the dynamic moments of inertia [Formula Presented] compared with the kinematic moments of inertia [Formula Presented] seen both in experiment and in calculations at high rotational frequencies indicate the high energy cost to build the states at high spin and reflect the limited angular momentum content in these configurations.
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2. |
- Afanasjev, A. V., et al.
(author)
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The coexistence of the intruder vi13/2, superdeformed and terminating bands in the A ∼ 135 mass region
- 1996
-
In: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 608:2, s. 176-201
-
Journal article (peer-reviewed)abstract
- The configuration-dependent shell-correction approach with the cranked Nilsson potential is employed for a systematic investigation of the high-spin spectra of the nuclei in the A ∼ 135 (Z = 57-61, N = 72-78) mass region, where superdeformed bands have been observed. Main attention is paid to the coexistence of intruder νi13/2, superdeformed and terminating bands in the yrast region. Recent developments of the formalism allow the identification of the high-j orbitals in each N-shell, for example, the g9/2 orbitals in the N = 4 shell, after the diagonalization of the cranked Nilsson potential. This turns out to be quite important for the understanding of the high collectivity of the observed bands. It is shown that the equilibrium deformation of the superdeformed bands is strongly dependent on the number of the proton holes in the g9/2 orbitals. With increasing neutron number above N = 75, the intruder νi13/2 bands are calculated triaxial. Especially for Z = 57, but also for higher proton numbers, we calculate some coexistent oblate non-collective states which are yrast for specific spin values at I ≥ 40h.
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3. |
- Andreoiu, Corina, et al.
(author)
-
Yrast Superdeformed Band in 59Cu
- 2000
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 62:5, s. 513011-513015
-
Journal article (peer-reviewed)abstract
- High-spin states in 59Cu were populated using the fusion-evaporation reactions 28Si+40Ca at a beam energy of 125 MeV and 36Ar+28Si at a beam energy of 143 MeV. The Gammasphere array in conjunction with ancillary detector systems allowed for the identification of a superdeformed rotational band in 59Cu, which was firmly linked to low-spin yrast states. Using directional correlations of oriented states, a spin-parity assignment of Iπ = 25/2+ to the band head was possible. The average quadrupole moment of the band is measured to be Qt = (2.24±0.40) e b. The characteristics of the band are compared to neighboring nuclei and predictions of different mean-field theories.
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4. |
- Devlin, M., et al.
(author)
-
Superdeformation in 68Zn: Evidence for a New, Neutron-rich Island of Superdeformation in A~70 Nuclei
- 1999
-
In: Physical Review Letters. - 1079-7114. ; 82, s. 5217-5220
-
Journal article (peer-reviewed)abstract
- A superdeformed rotational structure is reported in the stable nucleus Zn-68. It has a transition quadrupole moment (Q(t)) of 2.5(-0.4)(+0.7) e b (beta(2) approximate to 0.4), as measured by the residual Doppler shift method. Theoretical calculations suggest that two different configurations are possible candidates for this band. One is built without h(11/2) neutrons, as seen in superdeformed bands in the A similar to 60 region, while the other involves one h(11/2) neutron in analogy with superdeformed bands in the A similar to 80 region. The second of these candidate configurations is preferred, thus establishing a new, neutron-rich (relative to the line of beta stability) region of superdeformation with Z similar to 30 and N similar to 38.
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5. |
- Döring, J., et al.
(author)
-
Band terminations in the valence space of 86Zr
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 61:3, s. 343101-343106
-
Journal article (peer-reviewed)abstract
- High-spin states in 86Zr up to 30+ and 27- were observed via the 58Ni(32S,4p) reaction at 135 MeV beam energy using the combined GAMMASPHERE and MICROBALL systems. Calculations performed with the configuration-dependent shell-correction approach show that these states are built from six g9/2 neutrons and at most four protons excited from the p1/2,p3/2,f5/2 subshells to the g9/2 subshell at small deformation. The highest observed states at 27- and 30+ are interpreted as band-terminating states with the latter having the highest spin available in the valence space for 86Zr.
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6. |
- Evans, AO, et al.
(author)
-
Magnetic properties of smooth terminating dipole bands in Te-110,Te-112
- 2006
-
In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 636:1, s. 25-30
-
Journal article (peer-reviewed)abstract
- Three strongly coupled sequences have been established in Te-110,Te-112 up to high spins. They are interpreted in terms of deformed structures built on proton 1-particle-1-hole excitations that reach termination at I similar to 40h. This is the first observation of smooth terminating dipole structures in this mass region. Lifetime measurements have allowed the extraction of experimental B(M 1; 1 -> I - 1) and B(E2; I -> I - 2) reduced transition rates for one of the dipole bands in Te-110. The results support the deformed interpretation. (c) 2006 Elsevier B.V. All rights reserved.
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7. |
- Evans, A. O., et al.
(author)
-
Magnetic properties of deformed dipole bands in Te-110,Te-112
- 2006
-
In: Physica Scripta. - 0031-8949. ; T125, s. 192-193
-
Journal article (peer-reviewed)abstract
- A lifetime analysis using the Doppler-shift attenuation method has been performed on the Tellurium isotopes Te-110,Te-112. The experiment was performed using the Gammasphere array in conjunction with the MICROBALL charged-particle detector. Three strongly coupled bands were previously established in Te-110,Te-112 which were observed up to unusually high spins. In the current experiment, it has been possible to extract lifetime measurements using a Doppler broadened lineshape analysis on one of the Delta I = 1 band structures in Te-110. In contrast to similar Delta I = 1 structures in other nuclei in this mass region, the extracted B(M1) values did not rapidly decrease with increasing angular momentum. Instead, the strongly coupled band in Te-110 represents a deformed 1p-1h structure, rather than a weakly deformed structure showing the shears mechanism.
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8. |
- Gizon, J., et al.
(author)
-
Terminating bands in the doubly odd nucleus [Formula Presented]
- 1999
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 59:2, s. 570-574
-
Journal article (peer-reviewed)abstract
- High spin states have been populated in [Formula Presented] using the reaction [Formula Presented] at 130 MeV. The γ rays have been detected with the EUROGAM2 array. The level structure of [Formula Presented] has been investigated. Several bands have been identified and established over a wide range of spin. They are interpreted using the Nilsson-Strutinsky cranking formalism and explained in terms of band terminations. Their configurations are built from the valence particles and valence holes relative to a [Formula Presented] core: [Formula Presented] protons (and [Formula Presented] proton holes) and [Formula Presented] and [Formula Presented] neutrons. After [Formula Presented] is the second heavy nucleus and the first odd-odd nucleus in which configurations in the valence space are followed from low spin up to their termination.
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9. |
- Ideguchi, E., et al.
(author)
-
High-spin intruder band in In-107
- 2010
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 81:3, s. 034303-
-
Journal article (peer-reviewed)abstract
- High-spin states in the neutron-deficient nucleus In-107 were studied via the Ni-58(Cr-52,3p) reaction. In-beam gamma rays were measured using the JUROGAM detector array. A rotational cascade consisting of ten gamma-ray transitions, which decays to the 19/2(+) level at 2.002 MeV, was observed. The band exhibits the features typical for smooth terminating bands that also appear in rotational bands of heavier nuclei in the A similar to 100 region. The results are compared with total Routhian surface and cranked Nilsson-Strutinsky calculations.
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10. |
- Ideguchi, E., et al.
(author)
-
Superdeformation in the Doubly Magic Nucleus 40Ca
- 2001
-
In: Physical Review Letters. - 1079-7114. ; 87:22
-
Journal article (peer-reviewed)abstract
- A rotational band with seven gamma -ray transitions between states with spin 2 (h) over bar and 16 (h) over bar has been observed in the doubly magic, self-conjugate nucleus Ca-40(20)20. The measured transition quadrupole moment of 1.80(-0.29)(+0.39)eb indicates a superdeformed shape with a deformation beta (2) = 0.59(-0.07)(+0.11). The features of this band are explained by cranked relativistic mean field calculations to arise from an 8-particle 8-hole excitation.
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11. |
- Kelsall, N.S., et al.
(author)
-
High-spin studies of N ~ Z nuclei in the mass 70 region
- 2003
-
In: AIP Conference Proceedings. - 0094-243X .- 1551-7616. ; :656, s. 261-268
-
Conference paper (peer-reviewed)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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12. |
- Kelsall, N. S., et al.
(author)
-
Testing mean-field models near the N=Z line : gamma-ray spectroscopy of the T-z=1/2 nucleus Kr-73
- 2002
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 65:4
-
Journal article (peer-reviewed)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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13. |
- LaFosse, D. R., et al.
(author)
-
Collective structures and band termination in 107Sb
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:1
-
Journal article (peer-reviewed)abstract
- High-spin states in the near proton-dripline nucleus 107Sb have been identified, and collectivity in this nucleus has been observed for the first time in the form of two rotational bands. One of the observed rotational structures is a ΔI = 1 band, and is interpreted as based on a π(g9/2)-1 ⊗ π(g7/2d5/2)2 proton configuration. A second structure has ΔI = 2 character, and is explained as being based on a πh11/2⊗[π(g9/2)-2 ⊗ π(g7/2d5/2)2] proton configuration through comparison with cranked Nilsson-Strutinsky model calculations. The calculations predict that this band terminates at a spin of 79/2 (Latin small letter h with stroke).
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14. |
- Lane, G. J., et al.
(author)
-
Identification of excited states in doubly odd [Formula Presented]Sb : Smooth band termination
- 1997
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 55:5, s. 2127-2131
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Journal article (peer-reviewed)abstract
- Excited states in [Formula Presented]Sb have been identified for the first time in a series of [Formula Presented]-spectroscopy experiments using both thin and backed targets, including neutron-fold and recoil-mass measurements to provide unambiguous channel identification. The three decoupled intruder bands observed in [Formula Presented]Sb are based upon configurations involving 2p-2h excitations across the [Formula Presented] shell gap and show the features of smooth band termination. The yrast intruder band, which has been connected to the low-spin levels, is tentatively identified up to its predicted termination at [Formula Presented]. Excellent agreement with configuration-dependent cranked Nilsson-Strutinsky calculations is obtained for the high-spin states near termination.
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15. |
- Mullins, S. M., et al.
(author)
-
Strong population of a superdeformed band in Eu142
- 1995
-
In: Physical Review C. - 0556-2813. ; 52:1, s. 99-103
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Journal article (peer-reviewed)abstract
- A superdeformed band has been found in Eu142. It is populated with 1.2(2)% of the total -ray intensity that decayed into Eu142 via the reaction Sn120(27Al,5n)142Eu at 152 MeV. The strength of the band is similar to that previously reported in Eu143, where the superdeformed band is populated with an intensity of 1.1(1)%. This is unexpected, since both total Routhian surface (TRS) and cranked modified oscillator (MO) calculations predict that the superdeformed band in Eu143 becomes yrast at lower spin than that in Eu142. This difference is 4Latin small letter h with stroke in the MO calculations and 8Latin small letter h with stroke in the TRS. Extrapolation of the normal-deformed yrast states in Eu143 shows, however, that a difference of 8Latin small letter h with stroke in spin corresponds to a change in the relative energy of the superdeformed and normal-deformed yrast lines of only 1 MeV.
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16. |
- O'Leary, C. D., et al.
(author)
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Evidence for isovector neutron-proton pairing from high-spin states in N = Z 74Rb
- 2003
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 67:2, s. 213011-213015
-
Journal article (peer-reviewed)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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17. |
- Paul, E.S., et al.
(author)
-
Gamma-ray spectroscopy of neutron-deficient Te-110. II. High-spin smooth-terminating structures
- 2007
-
In: Physical Review C: covering nuclear physics. ; 76, s. 1-034323
-
Journal article (peer-reviewed)abstract
- High-spin states have been populated in Te-110(52) via Ni-58(Ni-58,alpha 2p gamma) reactions at 240 and 250 MeV. The Gammasphere gamma-ray spectrometer was used in conjunction with the Microball charged-particle detector. The high-spin (I>30) collective level scheme of Te-110, up to similar to 45h, is discussed in this paper. Four new decoupled (Delta I=2) high-spin structures have been observed for the first time, together with two strongly coupled (Delta I=1) bands. These bands all show the characteristics of smooth band termination, and are discussed within the framework of the cranked Nilsson-Strutinsky approach.
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18. |
- Paul, E. S., et al.
(author)
-
Smooth terminating bands in Te-112: Particle-hole induced collectivity
- 2007
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:1
-
Journal article (peer-reviewed)abstract
- The Gammasphere spectrometer, in conjunction with the Microball charged-particle array, was used to investigate high-spin states in Te-112 via Ni-58(Ni-58, 4p gamma) reactions at 240 and 250 MeV. Several smooth terminating bands were established, and lifetime measurements were performed for the strongest one using the Doppler-shift attenuation method. Results obtained in the spin range 18-32h yield a transition quadrupole moment of 4.0 +/- 0.5eb, which corresponds to a quadrupole deformation epsilon(2)=0.26 +/- 0.03; this value is significantly larger than the ground-state deformation of tellurium isotopes. It was also possible to extract a transition quadrupole moment for the yrast band in Xe-114, produced via the 58Ni (58Ni, 2p gamma) reaction. A value of 3.0 +/- 0.5eb was found in the spin range 16-24h, which corresponds to a quadrupole deformation epsilon(2)=0.19 +/- 0.03. Cranked Nilsson-Strutinsky calculations are used to interpret the results.
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19. |
- Petrache, C. M., et al.
(author)
-
Stable triaxiality at the highest spins in 138Nd and 139Nd
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 61:1, s. 113051-113055
-
Journal article (peer-reviewed)abstract
- The nuclei 138Nd and 139Nd have been studied at very high spins via the 48Ca+94Zr reaction. Several new rotational bands were observed, four in 138Nd and two in 139Nd. The J(2) moments of inertia calculated from the observed γ-ray energies are very small and almost constant, indicating that these bands are triaxial. Cranked Nilsson-Strutinsky calculations reproduce the general behavior of the bands, supporting this interpretation and suggesting an approximately constant γ value of ∼ + 35° over a large spin range up to the highest observed spins. These bands and a few similar bands in other nuclei of the N≈80 region are a unique example of almost undisturbed triaxial bands.
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20. |
- Pfohl, J., et al.
(author)
-
Highly deformed rotational structures in 136Pm
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:3, s. 313041-313045
-
Journal article (peer-reviewed)abstract
- Four highly deformed structures in the odd-odd nucleus 13661Pm75 were observed via the 105Pd(35Cl,2p2n) reaction at 180 and 173 MeV using the GAMMASPHERE γ-ray spectrometer and the Microball charged-particle detector array. Quadrupole moment measurements were performed on all of the bands. In contrast to lighter odd-Ζ Pm and Pr nuclei, bands based on the g9/2[404]9/2 proton orbital were not observed. Instead, the four observed sequences are assigned as a coupling of an i13/2 neutron with the low-Ω h11/2 and mixed d5/2g7/2 orbitals. Comparisons with neighboring highly deformed structures are discussed and cranked Nilsson-Strutinsky calculations for 136Pm are presented.
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21. |
- Plettner, C., et al.
(author)
-
Very high rotational frequencies and band termination in 73Br
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:1, s. 143131-143136
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Journal article (peer-reviewed)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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22. |
- Rudolph, Dirk, et al.
(author)
-
Shell-model Influence in the Rotational Nucleus 86Mo
- 1996
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 54:1, s. 117-124
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Journal article (peer-reviewed)abstract
- High-spin states in Mo-86 were studied by means of the fusion evaporation reaction Ni-58(S-32,2p2n) Mo-86 at 135 MeV beam energy. Charged-particle-gamma gamma and -gamma gamma gamma coincidences recorded with the early implementation of the GAMMASPHERE array and the MICROBALL charged-particle detection system were used to largely extend the level scheme of the T-tau=1 nucleus Mo-86 to a possible spin of I=24h at 13 MeV excitation energy. The excitation scheme is compared to neighboring nuclei. There is evidence for enhanced shell-model influence in the 4 quasiparticle region (I=12-16h). The observed (pi=+,alpha=0) sequence at spin I greater than or equal to 16 h appears to be associated with a triaxial collective rotational band. This interpretation is supported by calculations within the configuration-dependent shell-correction approach with the cranked Nilsson potential.
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23. |
- Sarantites, D. G., et al.
(author)
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Triaxial superdeformed bands in [Formula Presented]
- 1998
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 57:1, s. 1-5
-
Journal article (peer-reviewed)abstract
- Four new superdeformed bands have been found in the nucleus [Formula Presented]. The good agreement between experiment and configuration-dependent shell correction calculations suggests that three of the bands have triaxial superdeformed shapes. Such unique features in mass [Formula Presented] superdeformed bands have been predicted, but not observed experimentally until now. A fourth band in [Formula Presented] is interesting due to a fairly constant and unusually high dynamic moment of inertia. Possible interpretations of this structure are discussed.
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24. |
- Simpson, J., et al.
(author)
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Discrete line γ-ray spectroscopy in the (50-60)ℏ spin domain of 161,162Er
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 62:2, s. 243211-243218
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Journal article (peer-reviewed)abstract
- Very high spin states (I=50-60ℏ) have been observed in the transitional nuclei 161Er and 162Er using the Euroball γ-ray spectrometer. In 161Er, three bands are observed well above spin 50ℏ. In the positive parity, positive signature (+, + 1/2) band a discontinuity in the regular rotational behavior occurs at 109/2+ and a splitting into two branches occurs at 97/2- in the negative parity, positive signature (-, + 1/2) band. The ( -, - 1/2) band continues in a regular fashion to 115/2-, tentatively (119/2-). In 162Er the positive parity, even spin (+, 0) yrast band is observed to continue smoothly up to 58+ (60+) and the negative parity, even spin (-,0) and odd spin (-,1) bands are extended from 30- to 34- and from 31- to 47- (49-), respectively. The high spin experimental spectra are compared with both a simple model involving the occupation of specific single neutron states in the absence of neutron pair correlations and with more detailed cranked Nilsson-Strutinsky calculations in which both proton and neutron pairing correlations are neglected. The very high spin domain is found to comprise a series of unpaired rotational bands. Unpaired band crossings between bands with different neutron and proton configurations are identified in 161Er. There is no evidence for aligned oblate or terminating states being close to the yrast line in 161,162Er up to spin ≈60ℏ in contrast to the lighter Er isotopes.
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25. |
- Smith, J. F., et al.
(author)
-
Identification of excited states in 119Ba
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 61:4
-
Journal article (peer-reviewed)abstract
- Excited states have been identified in the very neutron-deficient 119Ba nucleus. Two bands have been observed, which are likely to be based on h11/2 and (g7/2d5/2) neutron orbitals. Despite this being the first observation of excited states in 119Ba, the bands extend to (75/2)ℏ and (79/2)ℏ, respectively. The bands have been assigned to 119Ba using gamma-recoil and gamma-x-ray coincidences. Several quasiparticle alignments have been identified, involving neutron (h11/2)2 and proton (h11/2)2 aligned configurations. Furthermore, the bands show features which are reasonably consistent with smooth band termination at high spin. Theoretical results for 119Ba are discussed within the framework of cranked Woods-Saxon and Nilsson-Strutinsky calculations.
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