摘要:

Properties of low‐frequency octupole vibrations built on superdeformed rotational bands are investigated by means of the RPA in a uniformly rotating frame. Large configuration space composed of 9 major shells is used. Numerical examples are presented both for the152Dy and the192Hg regions. We always obtain extremely collective octupole vibrations withK=1, 2 and 3. It is shown that the properties of theK=1 octupole vibrations are especially sensitive to the amount of the static pairing correlations. Microscopic structures of these soft octupole vibrations and their character changes associated with the increase of the Coriolis‐mixing effects are investigated.

ISSN:0094-243X    

DOI:10.1063/1.42576

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.42582

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

In the first part of this contribution, the properties of the isoscalar giant monopole resonance in208Pb at zero temperature are studied in a self‐consistent model which employs a Skyrme‐type force and compared with experimental data. The coupling with the continuum is taken into account, as well as the coupling to two‐particle—two‐hole (2p‐2h) configurations containing a collective vibration. We extract the strength function of the mode and the branching ratios for the direct decay by neutron emission.In the second part, the experimental evidence testifying to the existence of a limiting temperature for the observation of gamma decay from the giant dipole resonance in hot nuclei is interpreted as indicating a remarkable constancy with temperature of the width with which the giant resonance couples to the compound nucleus.

ISSN:0094-243X    

DOI:10.1063/1.42584

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The intense decay of a five‐quasiparticle isomer in179W into the backbending region exposes for the first time a full set of S‐band states. A high value for the K‐quantum number is inferred from gamma‐ray branching ratios in the band‐crossing region, providing a basis for understanding the unusual decay of the isomer, as well as other highly K‐forbidden electromagnetic transitions in the A=180 region. The location of the full S‐band is discussed in connection with the superfluid‐to‐normal phase transition.

ISSN:0094-243X    

DOI:10.1063/1.42585

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.42586

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A statistical analysis of the distribution of level spacings for states with the same spin and parity is described in which the average spacing is calculated for the total ensemble. The resulting distribution of level spacings for states of deformed nuclei with A=155–185 and Z=62–77 is the closest to that of a Poisson distribution yet obtained for nuclear levels. However, when only the even‐spin, positive‐parity data for even‐even nuclei are considered, the level‐spacing distribution becomes double peaked. The anomalously‐large separations are shown to be the result of the low energy of the strongly‐correlated, completely‐paired yrast configuration of even‐even nuclei. Average values of the level spacings also are discussed as a function of spin, parity, and nuclear type (even‐even, even‐Z–odd‐N, etc.). Likewise, deviations from a Poisson distribution for several spacings (s) less than about 60 keV are compared with similar values for116Sn on an absolute scale. Such discrepancies are attributed to interactions (level repulsions) which become increasingly significant for s≤60 keV.

ISSN:0094-243X    

DOI:10.1063/1.42587

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.42588

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Different types of crossings between bands are discussed. New detailed spectroscopy allows the determination of the interaction strength with higher accuracy when the energies of both bands are established for some spin units in the crossing region and the decay pattern between them also taken into account. The well known crossing between the g‐band and the S‐band in even‐even nuclei is analysed and the expected oscillating dependence of the interaction strength on the Fermi level in the &ngr;i13/2subshell is established in the light rare earth region. A signature dependence of this strength for an odd‐Z nucleus is discussed in terms of a shape difference between the two signatures, which both have &ggr;≠0 below the rotational frequency of the crossing. In a new experiment carried out with the NORDBALL a crossing between bands built on the &pgr;h11/2and &pgr;h9/2configurations in163Tm has been established. From an analysis of the decay pattern at this crossing it is possible to extract new information on the shape difference between these two configurations which have very different driving forces. The results are discussed in relation to the shift of the &ngr;i13/2band crossing observed for the h9/2[541]1/2−configuration in this and many neighbouring odd‐Z nuclei.

ISSN:0094-243X    

DOI:10.1063/1.42589

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Experimental evidence for octupole deformation in the light actinide nuclei is illustrated through examples from high spin states physics. Recent experiments are reported and special attention is brought to effects observed in transitional nuclei where a new type of octupole deformation has presumably been observed.

ISSN:0094-243X    

DOI:10.1063/1.42590

出版商:AIP    

年代:1992

数据来源: AIP

ISSN:0094-243X    

DOI:10.1063/1.42592

出版商:AIP    

年代:1992

数据来源: AIP