Nuclear Data Sheets for A = 137☆

Nuclear Data Sheets for A = 131

Quadrupole pairing interaction and signature inversion

Rotational bands in the doubly odd nucleus 134Pr

Nuclear Data Sheets for A = 133

Excited states in the odd-odd nuclei 128,130La have been investigated to high spin using gamma -ray spectroscopy. Two distinct bands are seen, one based on a pi h11/2(X) nu h11/2 structure and the other on a pi h11/2(X) nu g7/2 configuration. Backbends are observed in both configurations for both nuclei and the nature of the particles responsible can be conclusively proved. Experimental variation in the energy-level signature splitting and B(M1)/B(E2) ratios are discussed in terms of the polarising effects of the odd proton and odd neutron on the soft collective core. The results are discussed in terms of the cranked shell model, odd-odd particle-rotor calculations and total Routhian surface calculations. They are also compared to neighbouring odd and odd-odd systems.

http://iopscience.iop.org/article/10.1088/0954-3899/15/4/012/pdf

The competition between collective and single particle behaviour in the odd-odd isotopes 128,130La

Excited states in the nuclei 128,130La have been investigated to high spin using gamma -ray spectroscopy techniques. In addition to the main rotational structures based on a prolate collective rotor, and a superdeformed band in 130La, two bands are seen with properties similar to the collective oblate structure proposed for 131La. The experimental evidence for these bands is discussed in terms of the variation in energy-level signature splitting, B(M1)/B(E2) ratios and mixing ratios as a function of rotational frequency and single-particle configuration. These results are interpreted using odd-odd particle-rotor model calculations and self-consistent cranking calculations. They are compared with the proposed 'collective oblate' bands in other nuclei in the A=130 region and possible evidence for collective oblate shape co-existence is presented.

http://iopscience.iop.org/article/10.1088/0954-3899/15/5/019/pdf

Collective oblate structure in the odd-odd isotopes 128,130La

The quadrupole moments (${\mathit{Q}}_{0}$) of the highly deformed, second minimum bands in $^{133}\mathrm{Nd}$ and $^{137}\mathrm{Nd}$ have been extracted from mean lifetime measurements using the Doppler shift attenuation method. The reactions $^{105}\mathrm{Pd}$${(}^{32}$S,2p2n${)}^{133}$Nd at 152 MeV and $^{104}\mathrm{Ru}$${(}^{36}$S,3n${)}^{137}$Nd at 145 MeV were used. A standard centroid shift analysis was carried out in both cases, which gave values of ${\mathit{Q}}_{0}$=(6.0\ifmmode\pm\else\textpm\fi{}0.7)e b and (4.0\ifmmode\pm\else\textpm\fi{}0.5)e b for $^{133}\mathrm{Nd}$ and $^{137}\mathrm{Nd}$, respectively, corresponding to axial prolate deformations of ${\mathrm{\ensuremath{\beta}}}_{2}$\ensuremath{\simeq}0.33 and \ensuremath{\simeq}0.22. A line-shape analysis was also carried out for $^{133}\mathrm{Nd}$ to check against the possible effect of sidefeeding. The result was ${\mathit{Q}}_{0}$=(6.7+0.7)e b, with sightly slower sidefeeding times corresponding to ${\mathit{Q}}_{\mathrm{sf}}$\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\simeq}5.3e b. The results are in good agreement with the predictions of total Routhian surface calculations, and are discussed in the context of other highly deformed bands in the A=130--140 mass region.

Second minimum lifetime measurements in 133Nd and 137Nd.

A mean lifetime measurement has been carried out on the states in the superdeformed band found in 131Ce using the Doppler shift attenuation method (DSAM). The measured intrinsic nuclear quadrupole moment is Q0 approximately=6 eb, assuming constant deformation, which corresponds to a quadrupole deformation beta 2 approximately=0.35. This is considerably smaller than the value deduced for 132Ce.

http://iopscience.iop.org/article/10.1088/0954-3899/16/4/016/pdf

Quadrupole moment of the superdeformed band in 131Ce

Six rotational bands have been established in 136Sm following heavy-ion induced reactions carried out at the Nuclear Structure Facility, Daresbury. The yrast band has been observed up to Ipi =(24+) and undergoes three band-crossings. A band was observed built on the low-lying 2+ gamma-vibrational state, in addition to two negative parity sidebands built on two-quasiproton excitations. A dipole band showing the characteristics of collective oblate rotation was also established. The results are discussed in terms of total Routhian surface and cranked Woods-Saxon model calculations.

https://iopscience.iop.org/article/10.1088/0954-3899/19/6/007/pdf

Y. J. He

Papers

The competition between collective and single particle behaviour in the odd-odd isotopes 128,130La

Collective oblate structure in the odd-odd isotopes 128,130La

Second minimum lifetime measurements in 133Nd and 137Nd.

Quadrupole moment of the superdeformed band in 131Ce

Prolate and oblate rotational bands in 136Sm