Description of deformed nuclei in the sdg boson model

Abstract

We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei.

Detailed spectroscopy of quadrupole and octupole states inYb168

“…A better agreement was found in Ref. [12] where the g boson was also included at the cost of additional free parameters. From the trajectories in the IBM symmetry triangle found in Ref.…”

“…The new transitions determined in the present experiments allow for a reliable deduction of the mixing with the yrast band. Using the E2 branching ratios of the 4+ and 6+ we have obtained Zp(4+) = 0.0110(54) and Zp(6+) = 0.0145(12), which agree within the error margins. For other states where both M1 and E2 transitions are possible…”

“…Since we are interested to see how well the CBS rotor model can reproduce the experimental B{E2) values, we define also the E2 transition operator, which takes the form [40] T f K=0(E2) = eeg(P/Pm)D2 m, (12) where eeff = e<i)pM(cosy)r is the effective charge and D denotes the Wigner function. Thus, the model provides three parameters to be adjusted to data: rp and Bpl, for level energies and eeft for transition probabilities.…”

“…These studies mostly concentrated on investigating the positive-parity states at low and medium spins. Various nuclear structure models have been employed to explain the structure of this nucleus and its neighboring isotopes, such as the interacting boson model (IBM) with different types of bosons [11][12][13][14], the interacting vector boson model [15], and the quasiparticle random phase approximation [16]. High-spin states have also been studied [5,17] and interpreted in the framework of the angular momentum projected Tamm-Dancoff approx imation [18].…”

Studies of the electric dipole transition of deformed rare-earth nuclei

“…The effect of the different terms in the transition operator may play different roles, a combination of them may conceal some of the properties of the individual term. For instance, in the SU(3) limit of the sdg-IBM, each term in the E2 transition operator has an L(L+3) dependence, which plays an important role at large L. But this dependence disappears for the SU(3) generator form of the E2 transition operator; this L(L+3) dependence term is concealed, and leads to the reduction of collectivity problem [36,37]. To see the effect of each individual term, we have calculated the reduced matrix elements of sp, dp and df terms respectively.…”