Proton Orbital[541]1/2 and Backbending in ^(178)W

The microscopic mechanism of nine experimentally observed bands in ^178W is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of nine bands in ^178W, are reproduced well by the particle-number conserving calculations, in which no free parameter is involved. Calculations demonstrate that occurrence of sharp backbending comes mainly from the contribution of high-j intruder orbitals vi13/2 or πh11/2 and their interference effect with orbitals near the Fermi surface. Theω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.

Study on Superdeformed Bands of ^(152)Dy and Its Neighboring Nuclei

152^Dy is the first observed superdeformed nucleus, whose band structure reflects the typical distribution of high j low Ω orbitals of superdeformed nuclei in A-150 mass region. The particle-number conserving treatment of the cranked shell model with monopole and quadrupole paring interactions is adopted to investigate the observed six superdeformed bands in 152^Dy. The π[523]7/2 orbital is emphasized for the first time to interpret the microscopic structure of band 2 and 3 of 152^Dy. A new comprehension is proposed on the basis of ever existing experimental and theoretical results, and the reliability is illustrated by several superdeformed bands of neighboring nuclei.

Microscopic Mechanism of Large Fluctuation in Odd-Even Differences in Moments of Inertia for Actinide Nuclei

The experimental large fluctuation in odd-even differences in moments ofinertia of deformed actinide nuclei is investigated using the particle-number conserving (PNC)method for treating the cranked shell model with monopole and quadrupole pairing interactions. PNCcalculations show that the large odd-even difference in moments of inertia mainly comes from theinterference contributions j(μv) from particles in high j intruder orbitals μ and v quite near theFermi surface, which have no counterpart in the BCS formalism. The effective monopole andquadrupole pairing interaction strengths are determined to fit the experimental odd-even differencesin binding energies and bandhead moments of inertia. The experimental results for the variation ofmoments of inertia with rotational frequency ω are reproduced well by the PNC calculation. Thenearly identical experimental moments of inertia between ~(236)U(gsb) and ~(238)U(gsb) at lowfrequencies hω ≤ 0.20 MeV are also reproduced quite well.

Effects of Rotation, Blocking and Octupole Deformation on Pairing Correlations in the U and Pu Isotopes

including octupole correlations in the Nilsson potential,the ground-state rotational bands in the reflection-asymmetric(RA)nuclei are investigated by using the cranked shell model(CSM)with the monopole and quadrupole pairing correlations treated by a particle-number-conserving(PNC)method.The experimental kinematic moments ofinertia(Mols)for alternating-parity bands in the even-even nuclei ^(236,238)U and ^(238,240)Pu,as well as paritydoublet bands in the odd-A nuclei 237U and 239Pu are reproduced well by the PNC-CSM calculations.The higher J(1)for the intrinsic s=-i bands in ^(237)U and ^(239)Pu,compared with the s=+1 bands in the neighboring even-even nuclei ^(236,238)U and ^(238,240)Pu,can be attributed to the pairing gap reduction due to the Pauli blocking effect.The gradual increase of J(i)versus rotational frequency can be explained by the pairing gap reduction due to the rotation.The Mols of reflection-asymmetric nuclei are higher than those of reflection-symmetric(RS)nuclei at low rotational frequency.Moreover,the inclusion of a larger octupole deformation 8,in the RA nuclei results in more significant pairing gap reduction compared with the RS nuclei.

Shape change induced by g_(9/2) rotational alignment in ^(84,86)Mo

Neutron-deficient Z ≈ N nuclei84,86Mo have been investigated using pairing-deformation self-consistent cranked shell modelcalculations up to spin I > 20 . Our calculations are in good agreement with the experimental data, indicating γ-soft triaxial shapesat low rotational frequency and well-deformed triaxial-oblate shapes at high rotational frequency for both nuclei. The shape changeis due to the alignments of the g9/2protons and g9/2neutrons.

High-spin states and signature inversion in odd-odd ^(182)Au

High-spin states in182Au have been produced and studied via the152Sm(35Cl,5nγ)182Au reaction. The level scheme consisting of the πh 9/2?νi 13/2 and πi 13/2?νi 13/2 bands has been established for the first time. The low spin signature inversion in both bands has been found. The observed signature inversion phenomena can be interpreted qualitatively using the pairing and deformation self-consistent cranked Wood-Saxon calculations.

Backbendings of superdeformed bands in ^(36,40)Ar

Experimentally observed superdeformed(SD) rotational bands in36Ar and40Ar are studied by the cranked shell model(CSM) with the pairing correlations treated by a particle-number-conserving(PNC) method.This is the first time that PNC-CSM calculations have been performed on the light nuclear mass region around A=40.The experimental kinematic moments of inertia J~((1))versus rotational frequency are reproduced well. The backbending of the SD band at frequency around ω =1.5 Me V in36Ar is attributed to the sharp rise of the simultaneous alignments of the neutron and proton 1 d5/2[202]5/2 pairs and 1 f7/2[321]3/2 pairs, which is a consequence of the band crossing between the 1 d5/2[202]5/2 and 1 f7/2[321]3/2 configuration states. The gentle upbending at low frequency of the SD band in40Ar is mainly affected by the alignments of the neutron 1 f7/2[321]3/2 pairs and proton 1 d5/2[202]5/2 pairs.The PNC-CSM calculations show that besides the diagonal parts, the off-diagonal parts of the alignments play an important role in the rotational behavior of the SD bands.

Phase transition in odd-N Pd-isotopes

Phase transition in odd-N isotopes ^99,101,103 Pd are investigated via the E-GOS（E-Gamma Over Spin）curves, which strongly suggest a structure evolution from vibration to rotation along the yrast lines with increasing spin. Theoretical calculations have been performed for the ground state bands of ^99,101,103 Pd in the framework of the cranked shell model（CSM） and the alignment properties observed experimentally are analyzed employing this model. The results show that the phase transition in the ground state bands of ^99,101,103 Pd can be interpreted as the valence nucleons start to occupy the g9/2 proton orbitals with increasing spin which would polarize the core to a small, but rigid quadrupole deformation.