Nuclear Data Sheets for A = 137☆

The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with [Formula: see text]. The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.

https://iopscience.iop.org/article/10.1088/0034-4885/79/7/076301/pdf

Review of metastable states in heavy nuclei

Rotational bands in the doubly odd nucleus 134Pr

Nuclear Data Sheets for A = 212

Nuclear Data Sheets for A=212

The level structures of the doubly-odd nuclei $^{136}\mathrm{Pm}$ and $^{134}\mathrm{Pr}$ have been studied to high spin following the reactions $^{114}\mathrm{Cd}$${(}^{27}$Al,5n${)}^{136}$Pm, $^{116}\mathrm{Sn}$${(}^{24}$Mg,p3n${)}^{136}$Pm, and $^{114}\mathrm{Cd}$${(}^{27}$Al,\ensuremath{\alpha}3n${)}^{134}$Pr. The two nuclei show very similar collective features. In both nuclei a rotational band built on the \ensuremath{\pi}${h}_{11/2}$\ensuremath{\bigotimes}\ensuremath{\nu}${h}_{11/2}$ configuration has been observed. This band shows a constant signature splitting of \ensuremath{\sim}50 keV with no backbend in both cases. In addition, a sideband built on the \ensuremath{\pi}${[413](5/2}^{+}$\ensuremath{\bigotimes}\ensuremath{\nu}${h}_{11/2}$ configuration has been observed in $^{136}\mathrm{Pm}$. This band becomes yrast at high spins and shows a gain in alignment of \ensuremath{\sim}8\ensuremath{\Elzxh} at a frequency of \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\sim}0.28 MeV due to the decoupling of a pair of ${h}_{11/2}$ protons. In $^{134}\mathrm{Pr}$ the sideband was only observed above the band crossing. Experimental ratios of reduced transition probabilities, B(M1)/B(E2), have been extracted from transitions within the bands and compared to theoretical values obtained from a semiclassical model.

Similar rotational band structures in doubly-odd 136Pm and 134Pr

Excited states in 212,213Rn were populated in the bombardment of 204Hg by 14C ions of energies 80-94 MeV. The depopulation of the excited states was studied using in-beam spectroscopic methods including γ-ray excitation, γ-ray angular distribution, γ-γ-t coincidence, pulsed-beam-γ timing and conversion electron measurements. Spins up to Jπ = 30 and a tentative J = (73/2) were observed, respectively. In 212Rn the previous level scheme was confirmed, with the addition of five new transitions of which one feeds the 30+ state. In 213Rn the previously reported level scheme was mainly confirmed and it was extended to (71/2) or (73/2), which is the highest spin observed to-date in a lead-region nucleus. Several transition rates B(λ) were deduced from isomeric half-lives or branching ratios in both isotopes. Deformed Independent Particle Model (DIPM) calculations were performed to assign configurations, which in 213Rn usually consist of the odd neutrons vg9/2 and vj15/2 coupled to the four-proton states in 212Rn. The highest levels include neutron core-excitations, since the maximum valence-nucleon angular momentum in 213Rn is 55/2. The very topmost levels even need 2- particle-two-hole excitations. Shape changes in these two Rn isotopes are discussed, as are the transition rates.

Very-high-spin and core-coupled states in 213Rn. a test of the applicability of the deformed independent particle model

Collective bands based on a low-K \ensuremath{\pi}${h}_{11/2}$ orbital have been populated to high spins in the odd-proton nuclei $^{135}$,137Pm following the reactions $^{116}\mathrm{Sn}$${(}^{24}$Mg,p4n${)}^{135}$Pm and $^{114}\mathrm{Cd}$${(}^{27}$Al,4n${)}^{137}$Pm, respectively. Both nuclei exhibit a band crossing in the \ensuremath{\pi}${h}_{11/2}$ band at a frequency of \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\sim}0.42 MeV. In $^{135}\mathrm{Pm}$, an upbend is observed, while a weaker interaction backbend is observed in $^{137}\mathrm{Pm}$. Cranked-shell model calculations, including triaxiality, imply that this crossing is due to the alignment of the second and third valence ${h}_{11/2}$ protons. The systematics of this alignment in the Pm isotopes will be discussed. In addition, positive parity three-quasiproton states were observed in both nuclei. These structures also contain a pair of aligned ${h}_{11/2}$ protons, in this case the first and second valence protons which align at a much lower frequency of \ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\sim}0.28 MeV.

L. Hildingsson

Papers

Similar rotational band structures in doubly-odd 136Pm and 134Pr

Very-high-spin and core-coupled states in 213Rn. a test of the applicability of the deformed independent particle model

Collective band structures in the odd-proton nuclei 135,137Pm.