| 1. |
- Svensson, C. E., et al.
(author)
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Decay Out of the Doubly Magic Superdeformed Band in the N=Z Nucleus 60Zn
- 1999
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In: Physical Review Letters. - 1079-7114. ; 82:17, s. 3400-3403
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Journal article (peer-reviewed)abstract
- The doubly magic superdeformed band in the N = Z nucleus Zn-60 has been identified. Linking transitions connecting this band to the yrast line provide the first spin, parity, and excitation energy measurements for superdeformed states in the A similar to 60 region. The stretched-E2 character and relatively large B(E2) values of these transitions suggest a nonstatistical decay-out process.
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| 2. |
- Svensson, C. E., et al.
(author)
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Observation and Quadrupole Moment Measurement of the First Superdeformed Band in the A~60 Mass Region
- 1997
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In: Physical Review Letters. - 1079-7114. ; 79:7, s. 1233-1236
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Journal article (peer-reviewed)abstract
- A high-spin rotational cascade of six gamma rays has been observed in Zn-62. The quadrupole moment of 2.7(-0.5)(+0.7) e b measured for this band corresponds to a deformation beta(2) = 0.45(-0.07)(+0.10). The properties of this band are in excellent agreement with calculations that predict high-spin superdeformed bands in Zn-62 with deformations beta(2) = 0.41-0.49. These results establish a new region of superdeformation for nuclei with neutron and proton numbers N, Z approximate to 30-32.
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| 3. |
- Svensson, C. E., et al.
(author)
-
Smooth Termination of Rotational Bands in 62Zn: Evidence for a Loss of Collectivity
- 1998
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In: Physical Review Letters. - 1079-7114. ; 80:12, s. 2558-2561
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Journal article (peer-reviewed)abstract
- Two sets of strongly coupled rotational bands have been identified in Zn-62. These bands have been observed up to the terminating states of their respective configurations. Lifetime measurements indicate that the transition quadrupole moments in these bands decrease as termination is approached. These results establish the first terminating states of rotational bands in the A similar to 60 mass region and confirm the predicted loss of collectivity associated with smooth band termination.
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| 4. |
- Gadea, A., et al.
(author)
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Spectroscopy at N=Z with EUROBALL III
- 1999
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In: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 495, s. 195-198
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Conference paper (peer-reviewed)abstract
- A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to the high resolution gamma measurement and accurate DCO's or angular distributions, the information concerning the Electric or Magnetic character of the transition. This information for transitions in nuclei far from stability valley is now reachable in the new generation of Ge-arrays based in composite detectors. EUROBALL III is a good example with the high polarization sensitivity of the 90 degrees ring of Clovers. The Polarization correlations PCO's measured in coincidence with the Cluster detectors permits to investigate transitions in weakly populated nuclei. In this contribution we present results on medium mass N=Z nuclei measured with EUROBALL III coupled with light particle ancillary detectors.
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| 5. |
- Yu, C. H., et al.
(author)
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Comparison of Superdeformed Bands in 61Zn and 60Zn: Possible Evidence for T=0 Pairing
- 1999
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 60:3
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Journal article (peer-reviewed)abstract
- The yrast superdeformed band in Zn-61 has been established using Si-28(Ar-36, 2pn)Zn-61 and Ca-40(Si-29, 2 alpha)Zn-61 fusion-evaporation reactions. The excitation energy of this band was determined via two transitions that link this band to the normally deformed states. Lifetime analysis of this band resulted in a quadrupole moment of Q(t) = 3.0 +/- (0.5)(0.4)e b, which corresponds to a deformation of beta(2) = 0.50+/-(0.07)(0.06). A comparison of the J((2)) dynamical moments of inertia of the yrast superdeformed band in Zn-61 with those in Zn-60 shows a nearly complete blocking of the observed alignment in Zn-60, indicating that T=0 proton-neutron pair correlations may be present in Zn-60. [S0556-2813(99)51109-6].
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| 6. |
- Andersson, T., et al.
(author)
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High-spin States in the A=39 Mirror Nuclei 39Ca and 39K
- 1999
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In: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 6, s. 5-8
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Journal article (peer-reviewed)abstract
- High-spin states of the mass A = 39 mirror pair K-39 and Ca-39 were investigated via the fusion-evaporation reaction Si-28+O-16 at 125 MeV beam energy. The GAMMASPHERE array in conjunction with the 4 pi charged-particle detector array MICROBALL and neutron detectors was used to detect gamma rays in coincidence with evaporated light particles. The results of the first high-spin study of the T-z = -1/2 nucleus Ca-39 are discussed in terms of mirror symmetry and compared to spherical shell-model calculations in the 1d(3/2)-1f(7/2) configuration space.
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| 7. |
- Repsilber, Dirk, 1971-, et al.
(author)
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Formation of metastable RNA structures by sequential folding during transcription : time-resolved structural analysis of potato spindle tuber viroid (-)-stranded RNA by temperature-gradient gel electrophoresis
- 1999
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In: RNA. - New York, USA : Cambridge University Press. - 1355-8382 .- 1469-9001. ; 5:4, s. 574-84
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Journal article (peer-reviewed)abstract
- A model of functional elements critical for replication and infectivity of the potato spindle tuber viroid (PSTVd) was proposed earlier: a thermodynamically metastable structure containing a specific hairpin (HP II) in the (-)-strand replication intermediate is essential for template activity during (+)-strand synthesis. We present here a detailed kinetic analysis on how PSTVd (-)-strands fold during synthesis by sequential folding into a variety of metastable structures that rearrange only slowly into the structure distribution of the thermodynamic equilibrium. Synthesis of PSTVd (-)-strands was performed by T7-RNA-polymerase; the rate of synthesis was varied by altering the concentration of nucleoside triphosphates to mimic the in vivo synthesis rate of DNA-dependent RNA polymerase II. With dependence on rate and duration of the synthesis, the structure distributions were analyzed by temperature-gradient gel electrophoresis (TGGE). Metastable structures are generated preferentially at low transcription rates--similar to in vivo rates--or at short transcription times at higher rates. Higher transcription rates or longer transcription times lead to metastable structures in low or undetectable amounts. Instead different structures do gradually appear having a more rod-like shape and higher thermodynamic stability, and the thermodynamically optimal rod-like structure dominates finally. It is concluded that viroids are able to use metastable as well as stable structures for their biological functions.
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| 8. |
- Rudolph, Dirk, et al.
(author)
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Shell-model Influence in the Rotational Nucleus 86Mo
- 1996
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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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| 9. |
- Rudolph, Dirk, et al.
(author)
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The 3701 keV Neutron g9/2 Single-particle State in 57Ni
- 1999
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In: European Physical Journal A. Hadrons and Nuclei. - 1434-6001. ; 6, s. 377-380
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Journal article (peer-reviewed)abstract
- The neutron g(9/2) single-particle state in Ni-57 has been unambiguously identified in a combined measurement of the linear polarization, angular distribution, and angular correlation of gamma rays following the fusion-evaporation reaction Si-28(S-32,2pn)Ni-57 at a beam energy of 90 MeV. The linear polarization was measured with a EUROBALL cluster detector and a prototype of an encapsulated six-fold segmented hexaconical Ge-detector. The spin of the 3701 keV level in Ni-57 was confirmed to be I = 9/2 and its parity determined to be positive.
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| 10. |
- Sun, H., et al.
(author)
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New Band Structures and an Unpaired Crossing in 78Kr
- 1999
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 59:2, s. 655-664
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Journal article (peer-reviewed)abstract
- High-spin states in Kr-78 were studied using the Ni-58(Na-23,3p) reaction at 70 MeV and the Ni-58(Si-23,alpha 4p) reaction at 130 MeV. Prompt gamma-gamma coincidences were measured using the Pitt-FSU detector array and the GAMMASPHERE-MICROBALL array. Results from these experiments have led to 26 new excitation levels, some of which have been grouped into 3 new bands. Spins were assigned based on directional correlations of oriented nuclei. Two of the new negative-parity bands appear to form a signature-partner pair based on a two-quasineutron structure, in contrast to the previously known two-quasiproton negative-parity bands. A forking has been observed at the 24(+) state in the yrast band, which calculations suggest may result from an unpaired crossing. The available evidence suggests oblate shapes in the yrast band coexist with prolate shapes in the negative-parity bands. [S0556-2813(99)04602-6].
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