| 1. |
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| 2. |
- Baldsiefen, G, et al.
(author)
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Shears bands in Pb-193
- 1996
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 54:3, s. 1106-1116
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Journal article (peer-reviewed)abstract
- Four bands of enhanced dipole transitions, with weak crossovers, have been observed in Pb-195. Three of these bands are connected to the spherical levels. in addition, the spherical level scheme has been extended. The nuclear spectroscopy was done with the early implementation of GAMMASPHERE and HERA arrays of Get detectors. The nucleus Pb-193 was populated in the Yb-174(Mg-24,5n) reaction at beam energies of 129, 131, and 134 MeV. The experimental results are compared to tilted-axis cranking calculations. The systematical behavior of the dipole bands in the heavier odd-A Pb isotopes, Pb-195,Pb-197,Pb-199,Pb-201, is also discussed.
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| 3. |
- Clark, R M, et al.
(author)
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Superdeformation in bismuth
- 1996
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:1, s. 117-123
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Journal article (peer-reviewed)abstract
- High angular momentum states in Bi-195-197 are populated in two reactions: W-183(F-19,xn)Bi-202-x and Ta-181(Ne-20,xn)Bi-201-x at beam energies of 108 and 123 MeV, respectively. Gamma rays were detected using the Gammasphere array. Three weakly populated rotational sequences have been found. They each have properties characteristic of other superdeformed bands in this mass region. On the basis of cross-bombardment information we believe that one band belongs to each of Bi-195, Bi-196, and Bi-197. The properties of the bands in the odd-Bi nuclei are best reproduced if the odd proton occupies the favored signature of the [651]1/2 orbital, while the band in Bi-196 has this same proton configuration coupled to an additional N=7 (j(15/2)) neutron. The relative behavior of the J((2)) moments of inertia can be qualitatively understood in terms of Pauli-blocking effects.
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| 4. |
- Beausang, C W, et al.
(author)
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Lifetimes of yrast and excited superdeformed states in Gd-150 : effect of particle-hole excitations on the deformation
- 1998
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In: Physics Letters B. - 0370-2693 .- 1873-2445. ; 417:1-2, s. 13-19
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Journal article (peer-reviewed)abstract
- The quadrupole moments and deformations have been measured for six superdeformed bands in Gd-150. The results indicate evidence for deformation driving properties of both the high-hi intruder and also low-N natural parity states at the superdeformed Fermi surface. Several new transitions have been identified and placed in the low spin non-yrast portion of one of the SD bands.
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| 5. |
- Asztalos, S J, et al.
(author)
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Spin yields of neutron-rich nuclei from deep inelastic reactions
- 1999
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 60:4
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Journal article (peer-reviewed)abstract
- The potential for using deep inelastic reactions to populate high-spin states in neutron-rich nuclei is studied in a series of experiments using GAMMASPHERE for gamma-ray detection and a silicon strip detector for measuring the angles of projectilelike and targetlike fragments. In three experiments 61 new transitions up to a maximum spin of 22 (h) over bar in 12 neutron-rich rare-earth nuclei were found. We observe that gamma-ray yields as a function of spin are flatter for all neutron transfer products than for inelastic excitation of either the projectile or target nucleus. Calculations are presented which indicate that this difference cannot be accounted for by quasielastic processes, but more likely are the result of larger energy loss processes, such as deep inelastic reactions. [S0556-2813(99)06009-4].
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| 6. |
- Brinkman, M J, et al.
(author)
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Decay from a superdeformed band in Pb-194
- 1996
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:4, s. R1461-R1464
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Journal article (peer-reviewed)abstract
- Three experiments using the (174) Yb(Mg-25,5n)Pb-194 reaction have been undertaken at the Early Implementation of Gammasphere to study the decay of known superdeformed states in Pb-194. A single discrete transition with an energy of 2.746(2) MeV carrying 6(2)% of the full superdeformed band intensity has been identified. A discussion of our results and the assignment of the 2.746-MeV transition as a discrete gamma ray directly connecting the superdeformed 8(+) and low-lying 6(+) levels will be presented.
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| 7. |
- Joss, D T, et al.
(author)
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Lifetime measurements of a triaxial band in Ce-133
- 1998
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In: Acta Physica Hungarica A. - 1219-7580 .- 1588-2675. ; 7:1, s. 111-112
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Journal article (peer-reviewed)abstract
- The Doppler shift attenuation method has been used to determine the transition quadrupole moment of a triaxial band belonging to the gamma-soft nucleus, Ce-133. Doppler broadened lineshape (DBLS) analysis has revealed the magnitude of the Q(t) value to be similar to 2.4 eb. This contribution provides new information of (i) the transition quadrupole moment of this band (ii) the lifetimes of in-band and sidefeeding transitions and (iii) the relative deformations of coexisting nuclear shapes.
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| 8. |
- Joss, D T, et al.
(author)
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Lifetime measurements of a triaxial band in Ce-133
- 1998
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 58:6, s. 3219-3222
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Journal article (peer-reviewed)abstract
- Lifetimes of states within a triaxial band belonging to;the gamma-soft nucleus Ce-133 have been determined through a Doppler-broadened line shape analysis. A value, Q(t)approximate to 2.2 eb, has been found for the transition quadrupole moment which is considerably smaller than that of superdeformed structures (Q(t)approximate to 7.4 e b) in this mass region. The results are discussed in terms of deformation self-consistent calculations based on the total Routhian surface formalism. [S0556-2813(98)01912-8].
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| 9. |
- Clark, R M, et al.
(author)
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Relative deformations of superdeformed bands in Ce-131,Ce-132
- 1996
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 76:19, s. 3510-3513
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Journal article (peer-reviewed)abstract
- The quadrupole moments Q(0) of five superdeformed bands in Ce-131,Ce-132 have been established using the Doppler-shift attenuation method; for the first time, we can compare relative deformations of yrast and excited bands in different nuclei to an accuracy of similar or equal to(5-7)%. Four of the five bands have very similar deformations, while the excited band in Ce-131 has a somewhat larger quadrupole moment. Important new information is presented on the shape-driving force of the vi(13/2) orbital, the stability of the second minimum with respect to particle excitations, the relative deformations of identical bands, the nature of the sidefeeding, and the time scale of the decay process.
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| 10. |
- McNabb, D P, et al.
(author)
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Superdeformation in Po-198
- 1996
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:2, s. R541-R543
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Journal article (peer-reviewed)abstract
- The Yb-174(Si-29,5n) reaction at 148 MeV with thin targets was used to populate high-angular momentum states in Po-198. Resulting gamma rays were observed with Gammasphere. A weakly populated superdeformed band of 10 gamma-ray transitions was found and has been assigned to Po-198. This is the first observation of an SD band in the A approximate to 190 region in a nucleus with Z > 83. The J((2))) of the new band is very similar to those of the yrast SD bands in Hg-194 and Pb-196. The intensity profile suggests that this band is populated through states close to where the SD band crosses the yrast line and the angular momentum at which the fission process dominates.
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| 11. |
- FALLON, P, et al.
(author)
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PROTON AND NEUTRON EXCITATIONS IN SUPERDEFORMED TB-150
- 1995
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 52:1, s. 93-98
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Journal article (peer-reviewed)abstract
- Two new superdeformed (SD) bands have been observed in Tb-150 using the reaction P-31 + Sn-124 and the GAMMASPHERE detector array. These new bands are interpreted as being excited SD configurations involving a proton and a neutron particle-hole excitation, respectively. The configurations are discussed in terms of the occupancy of high-N intruder orbitals. These data are used to provide information on (i) the contribution to the dynamic moments of inertia due to the occupation of specific orbitals, (ii) the deformation driving effects of the particle-hole states, and (iii) the consequences of these effects on pairing and band crossings.
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| 12. |
- Lee, I Y, et al.
(author)
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Study of neutron-rich nuclei using deep-inelastic reactions
- 1997
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 56:2, s. 753-759
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Journal article (peer-reviewed)abstract
- We have used the Ca-48+Yb-176 reaction to study the population of high-spin states in neutron-rich nuclei by deep-inelastic reactions. Using Gammasphere, we observed gamma transitions from nuclei several neutrons richer than the target. Yrast states with spin up to 20 were populated in this reaction. High-spin states in Yb-175,Yb-177,Yb-178 were observed. In this region of reduced pairing, a reference based on experimental data was used to derive experimental Routhians. Systematics of experimental Routhians in neutron-rich Yb nuclei compare well with cranked shell-model calculations.
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| 13. |
- Marcaide, J. M., et al.
(author)
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Discovery of shell-like radio-structure in SN1993J
- 1995
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In: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 373:6509, s. 44-45
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Journal article (peer-reviewed)abstract
- SUPERNOVA explosions are poorly understood, partly because of difficulties in modelling them theoretically(1), and partly because there have been no supernovae observed in our Galaxy since the invention of the telescope. But the recent discovery(2) of supernova SN1993J in the nearby galaxy M81 offers an opportunity to investigate the evolution of the remnant, and its interaction with the surrounding interstellar medium, at high resolution. Here we present radio observations of SN1993J, made using very-long-baseline interferometry, which show the development of a shell structure. This 8-month-old radio shell is the youngest ever discovered in a supernova. The data suggest that the supernova explosion and the expanding shell of the remnant have nearly spherical symmetry, with small deviations where some parts of the shell are brighter than others. If these deviations arise because of variations in the density of the shell, this may reconcile earlier reports of symmetric radio emission(3) with the observed optical asymmetry(4,5), as the density variations could easily cause the latter. We infer that the radio emission is generated at the interface(6-9), where the surrounding gas is shocked by the ejecta.
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