Negative parity bands in even–even isotopes of Ra, Th, U and Pu

There are negative parity bands, conveniently labelled Kπ = 0−, 1− and 2−, with very similar patterns of excitation energies in many of the even–even isotopes of Ra, Th, U and Pu. Furthermore, the 3− states in many of these bands decay to the 0+ ground state with reduced B(E3) transition strengths closely similar to one another and comparable to the strengths found in the isotopes of Pb. We propose a Pb core plus exotic cluster model explanation of these observations. Such a treatment accounts for the persistence of these features across many isotopes and gives a good description of the excitation energies and E3 rates for all of them. The wavefunctions generated are intermediate between the weak and strong coupling limits. They suggest that the Kπ = 1− bands consist of doublets, possibly inverted, and thereby give rise to a novel proposal for a unification of some of the disparate band structures seen in 238U.

[1]  B. Buck,et al.  Parameter-free characterization of nuclear band spectra , 2007 .

[2]  B. Buck,et al.  Negative parity bands in 238U , 2007 .

[3]  W. Scheid,et al.  Parity shift and beat staggering structure of octupole bands in a collective model for quadrupole-octupole-deformed nuclei , 2006, nucl-th/0603057.

[4]  D. Lenis,et al.  Parameter-free solution of the Bohr Hamiltonian for actinides critical in the octupole mode , 2005, nucl-th/0512017.

[5]  Balraj Singh,et al.  Nuclear Data Sheets for A = 240☆ , 2004 .

[6]  D. Kusnezov,et al.  Octupole correlations in U and Pu nuclei , 2003 .

[7]  M. J. Martin,et al.  Nuclear Data Sheets for A = 238 , 2002 .

[8]  Y. A. Akovali Nuclear Data Sheets for A = 242 , 2002 .

[9]  W. Scheid,et al.  Cluster interpretation of parity splitting in alternating parity bands , 2001 .

[10]  B. Buck,et al.  Normal and superdeformed cluster bands in heavy nuclei , 2000 .

[11]  B. Buck,et al.  Systematic study of exotic clustering in even-even actinide nuclei , 1998 .

[12]  N. Zamfir,et al.  Octupole states in deformed actinide nuclei with the interacting boson approximation , 1998 .

[13]  B. Buck,et al.  Alternative view of collective bands in actinide nuclei , 1998 .

[14]  D. Cline,et al.  High-spin properties of octupole bands in 240 Pu and 248 Cm , 1998 .

[15]  B. Buck,et al.  Exotic clustering in 232,234,236,238U , 1997 .

[16]  B. Buck,et al.  Exotic clustering in 222,224,226Ra , 1997 .

[17]  B. Buck,et al.  Mass-symmetric form for cluster-core potentials , 1997 .

[18]  P. A. Butler,et al.  Intrinsic reflection asymmetry in atomic nuclei , 1996 .

[19]  H. R. Andrews,et al.  Rotational bands in 238U , 1996 .

[20]  Y. A. Akovali Nuclear data sheets for A = 226 , 1996 .

[21]  Pérez,et al.  Exotic cluster states in actinide nuclei. , 1996, Physical review letters.

[22]  B. Buck,et al.  Calculation of exotic decay half-lives for all observed cases , 1994 .

[23]  Y. A. Akovali Nuclear data sheets for A = 234 , 1994 .

[24]  H. Maier,et al.  Collective E1 transitions in even-A Ra, Th, and U nuclei , 1993 .

[25]  C. Fleischmann,et al.  Coulomb excitation of 226Ra , 1993 .

[26]  Y. A. Akovali Nuclear Data Sheets for A = 230 , 1993 .

[27]  I. N. Mikhailov,et al.  Coulomb excitation of230Th with32S,84Kr and142Nd projectiles , 1989 .

[28]  B. Buck,et al.  Rotational bands in deformed nuclei , 1987 .

[29]  R. Baldock,et al.  Alpha cluster states in 16 O , 1984 .

[30]  R. Simon,et al.  First Observation of Backbending in an Actinide Nucleus , 1983 .

[31]  N. Trautmann,et al.  Structure of high-spin states in 232Th, 234U and 236U , 1982 .

[32]  A. M. Friedman,et al.  Two-neutron quasiparticle states observed in $sup 236$U with the (d,p) reaction , 1973 .

[33]  M. E. Rose,et al.  Some Properties of the Racah and Associated Coefficients , 1952 .