Filtyp
Multiple superdeformed rotational bands have been identified in a nucleus for the first time. Cascades of 14, 13, and 11 transitions have been assigned to three bands in Dy153. Despite the small intensities, it has been possible to follow the decay of these bands from an angular frequency of 0.7 down to 0.4 MeV/Latin small letter h with stroke. In all three cases, the dynamic moment of inertia scr
The particle-rotor model using strong coupling basis functions is briefly reviewed. Recent developments are discussed. For example, a formalism for odd-odd nuclei (and negative parity states in even nuclei) is presented. With a standard neutron-proton interaction, measured spins and moments of transitional and deformed Ho nuclei are used to extract their main configurations. Total energy calculati
New high spin states in Mg25 (up to 13.3 MeV in excitation) have been located using the N12,p)25Mg reaction at a laboratory beam energy of 23.5 MeV. Gamma decay from 28 neutron unbound levels has been observed (24 of which are reported here for the first time) up to 7 MeV above the neutron drip line. Tentative identification of the yrast line up to (17/2+ has been made, along with an extension of
High-spin states in 154Dy have been studied using the TESSA2 γ-rays spectrometer following the 110Pd(48Ca,4n)154Dy reaction at a beam energy of 210 MeV. States up to 44+ and 37- have been observed. Below spin 30 the data display regular rotational behaviour which can be interpreted in terms of the cranked shell model. Above spin 30, sequences of levels connected by stretched E2 transitions, which
Six rotational bands up to energies Ex = 24.7 MeV and spins Jπ=(79/2−) have been identified in 109Sn using the GAMMASPHERE γ-detector array. Four of the bands show smoothly decreasing dynamic moments of inertia at rotational frequencies ℏω > 0.6 MeV. The bands arise at medium spins from a coupling of a valence d5/2, g7/2 or h11/2 neutron to the deformed 2p2h proton excitation of the Z=50 core 108S
The moments of inertia of rotational bands in the cranked harmonic oscillator are explored. The important role played by the maximum spin is pointed out. A qualitative agreement is found with the properties of recently observed superdeformed bands.
New high spin states in 25Mg have been located above the neutron threshold using the 12C(14N, pγ)25Mg reaction at E=23.5 MeV. The members of the ground state rotational band (Kπ= 5 2+ have been tentatively identified up to 15 2+. The yrast 15 2+ (not a member of the ground state band) and 17 2+ states have also been tentatively assigned. These results support the interpretation of the new 17 2+ st
General properties of terminating bands are briefly reviewed and exemplified on the observed high-spin properties ofl58Er andl56Er. The very similar features of the positive parity high-spin spectra of the N = 88 isotones of Dy, Er and Yb are pointed out and discussed. The possibility to estimate £(E2)-values in terminating bands from measured feeding times is explored. The spin contribution from
Predictions on terminating configurations in nuclei with 10-12 valence particles outside the 146Gd core are compared with recent experimental data. Observed and calculated spectra show a remarkable similarity, at least for 158Er and 156Er which nuclei are discussed in detail here.
It is shown that the band crossings observed at frequencies ≈h{stroke};hω ≈ 0.5 MeV can be qualitatively explained from Nilsson-Strutinsky calculations with no pairing correlations. The crossing bands are characterized by a different number of protons in h 11 2 orbitals leading to different deformationtrajectories in the (∋, γ)-plane. Above the band crossings, the calculated transition energies co
The evidence for ground-state octupole deformation in a region of nuclei around 145Ba is considered, and signatures that might be observed in the deformed single-particle states of odd-mass isotopes are calculated. The measured ground-state spins and electromagnetic moments of 145Cs and 145Ba can be accounted for by single-particle orbitals at the reflection-asymmetric equilibrium shape.
A comparison between the observed spectrum of 155Dy and calculations suggests that the yrast states in the I+30-40 region are built from bands whose deformation smoothly changes towards oblate shape (γ=60°) with band terminations in the I=45-50 region. The presence of other bands which show no terminating features is also naturally understood within the same theoretical framework.
The deexcitation of the 8.6 μs isomer of 9939Y has been studied using γ-ray spectroscopy techniques at LOHENGRIN and JOSEF. The resultant level scheme is analyzed within the ' framework of the particle-rotor coupling model. The ground-state band, to spin 19 2u+, is found to have band properties consistent with a π[422 5 2] Nilsson assignment. The 8.6 μs isomer and a side band with a band-head half
The unusual yrast spectrum of Yb158 at very high spins is interpreted in terms of a band termination at Iπ=36+. A similar spectrum with band terminations is obtained in microscopic cranking calculations for this nucleus. A basic element of the theory is that the finiteness of rotational bands is connected with a gradual shape change until the rotation takes place around a symmetry axis.
The collective and non-collective high-spin configurations in selected A {reversed tilde equals} 80 nuclei are analysed in detail using a shell-correction approach taking care of individual configurations and the pairing self-consistent cranking method with a non-axially-deformed Woods-Saxon potential. Shape transitions, shape coexistence, band-termination effects and alignment processes are discu
Magnetic Weyl semimetals have emerged as a fertile ground for exploring quantum phases of matter and quasiparticles. The latter includes unconventional fermions with larger Chern numbers than those of conventional Weyl fermions and topologically nontrivial band structures in bosonic excitations. They hold potential for further experimental exploration of emergent quantum matter, magnon-polarons, w
A method of calculating high-spin states of nuclei within the cranked Nilsson-Strutinsky framework is presented and discussed in some detail. With this method, various high-spin features of nuclei are studied, such as shape coexistence, shape changes, band crossings and band terminations. Nuclei with different mass numbers such as 106Pd, 118Te, 158Yb and 187Au are used to exemplify the formalism.
The effect of an octupole component in the intrinsic mean field at high spin is demonstrated by a Woods-Saxon-Bogolyubov cranking calculation. The nature of nuclear rotation becomes nearly collective instead of collective plus single-particle, because octupole couplings with l up to 3 "dilute" the high-j shells. Theory is consistent with experimental data on Th222 and could be tested further by st
The microscopic-macroscopic method Nilsson and Strutinsky is used to calculate potential energy surfaces with the modified oscillator potential for both neutron deficient, beta-stable and neutron excess nuclei. These calculationsreiterate the previous suggestion that in the medium mass nuclei with A ∼ 70-140 moderate deformation results from the cooperative formation of a potential minimum from th
Strutinsky-type potential-energy calculations are performed using various models for the microscopic as well as macroscopic energy terms. The following conclusions are nearly model-independent: Ra-Th nuclei around A {reversed tilde equals} 225 have ground-state equilibrium shapes with both quadrupole and octupole deformation; nuclei in the heavy barium region are just barely unstable with respect
