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High-spin states in the N = 128 nucleus 218Th have been investigated following fusion–evaporation reactions, using the recoil-decay tagging technique. Due to the short-lived nature of the ground state of 218Th prompt γ rays have been correlated with the α decay of the daughter nucleus 214Ra. The level scheme representing the decay of excited states has been extended to (16+) with the observation of six previously unreported transitions. The observations are compared with the results of shell model calculations and within the context of the systematics of neighbouring nuclei. [ABSTRACT FROM AUTHOR]

High-spin states of the odd–odd 194 Bi nucleus have been studied by means of nuclear spectroscopy for the first time. Two low-lying rotational bands were observed. The positive-parity band built on a short-lived isomeric state 633 keV above the α and β decaying long-lived (10 - ) state is assigned a π i 13 / 2 ⊗ ν i 13 / 2 - 1 configuration, while the other band is attributed to the π h 9 / 2 ⊗ ν i 13 / 2 - 1 configuration. Both of these bands are assumed to have oblate shape. Three band-like structures composed predominantly of Δ I = 1 transitions were also found. One of the shears band candidates is firmly linked to the lower lying level structures whereas for the other two links to lower-lying structures remain missing. [ABSTRACT FROM AUTHOR]

Low-lying negative-parity states in 11Be having dominant p-wave neutron configurations were studied using the 12B(d, ³He) 11Be proton-removal reaction in inverse kinematics. The 1/2-1 state at 0.32 MeV, the 3/2-1 state at 2.56 MeV, and one or both of the states including the 5/2-1 level at 3.89 MeV and the 3/2-2 level at 3.96 MeV were populated in the present reaction. Spectroscopic factors were determined from the differential cross sections using a distorted wave Born approximation method. The p-wave proton removal strengths were well described by the shell model calculations while the Nilsson model calculation underestimates the spectroscopic factors for the higher excited states. Results from both variational Monte Carlo and no-core shell-model calculations were also compared with the experimental observations. [ABSTRACT FROM AUTHOR]

Excited states have been observed for the first time in the very neutron-deficient odd-odd nucleus 57 120 La 63. The observed γ rays have been assigned based on coincidences with lanthanum X rays measured with the JUROGAM 3 array and with A = 120 fusion-evaporation residues measured with the MARA separator. The observed γ rays form a rotational band which decays to the ground state via a cascade of four low-energy transitions. Based on the systematic comparisons with the heavier odd-odd La isotopes we assign spin-parity 4 + to the ground state and a π h 11 / 2 ⊗ ν h 11 / 2 configuration to the rotational band. The nuclear shape has been investigated by the cranked Nilsson-Strutinsky model. Two quasiparticle plus triaxial rotor model calculations including the np interaction nicely reproduce the spin of the inversion between the even- and odd-spin cascades of E 2 transitions, giving credit to the np interaction as an important parameter responsible for the mechanism inducing the inversion. The position of the Fermi levels, in particular for neutrons, also has a strong impact on the observed inversion in the chain of lanthanum nuclei. [ABSTRACT FROM AUTHOR]

Excited states in the odd-odd, highly neutron-deficient nucleus 166Re have been investigated via the 92Mo(78Kr,3p1n)166Re reaction. Prompt γ rays were detected by the JUROGAM II γ-ray spectrometer, and the recoiling fusion-evaporation products were separated by the recoil ion transport unit (RITU) gas-filled recoil separator and implanted into the Gamma Recoil Electron Alpha Tagging spectrometer located at the RITU focal plane. The tagging and coincidence techniques were applied to identify the γ-ray transitions in Re166, revealing two collective, strongly coupled rotational structures, for the first time. The more strongly populated band structure is assigned to the πh11/2[514]9/2- ⊗ νi13/2[660]1/2+ Nilsson configuration, while the weaker structure is assigned to be built on a two-quasiparticle state of mixed πh11/2[514]9/2- ⊗ ν[h9/2f7/2]3/2- character. The configuration assignments are based on the electromagnetic characteristics and rotational properties, in comparison with predictions from total Routhian surface and particle-rotor model calculations. [ABSTRACT FROM AUTHOR]

The lifetime of the 2+ → 0g.s.+ transition in the neutron-deficicient nucleus 112Te has been measured for the first time using the DPUNS plunger and the recoil distance Doppler shift technique. The deduced value for the reduced transition probability is B(E2:0g.s.+ → 2+) = 0.46 ±0.04 e²b², indicating that there is no unexpected enhancement of the B(E20g.s.+ → 2+) values in Te isotopes below the midshell. The result is compared to and discussed in the framework of large-scale shell-model calculations. [ABSTRACT FROM AUTHOR]

Excited states in the neutron-deficient nucleus 72161Hf89 have been populated using the 118Sn(48Ti,5n) 161Hf and 110Pd(56Fe,5n) 161Hf fusion-evaporation reactions at 240 and 270 MeV, respectively. The level scheme for 161Hf has been extended with the observation of new band structures and an Iπ = (13/2+) isomeric state with a half-life of 4.8(2) μs has been identified. The decay path from this isomer to the (7/2-) ground state is established. The yrast band, based on the (13/2+) isomeric state, is extended up to (73/2+) and side band structures are identified up to (69/2-) and (55/2-). Quasiparticle assignments for these rotational structures are made on the basis of their alignment properties and Woods-Saxon cranked shell-model calculations. [ABSTRACT FROM AUTHOR]

Candidates for three excited states in the 66Se have been identified using the recoil-ß tagging method together with a veto detector for charged-particle evaporation channels. These results allow a comparison of mirror and triplet energy differences between analog states across the A = 66 triplet as a function of angular momentum. The extracted triplet energy differences follow the negative trend observed in the f7/2 shell. Shell-model calculations indicate that the strength of the Coulomb isotensor part alone is not sufficient to account for this trend in the case of the A = 66 triplet. [ABSTRACT FROM AUTHOR]

Abstract: Excited states in the proton-unbound nucleus 151Lu have been established using γ-ray coincidence techniques. The lifetime of the first excited state above the proton-emitting ground state has been measured using the recoil-distance Doppler-shift method combined with recoil-decay tagging. The experimental level scheme and extracted lifetime have been compared with state-of-the-art theoretical calculations based upon a non-adiabatic deformed Woods–Saxon potential. This comparison suggests that the proton-emitting ground state in 151Lu is mildly oblate with a deformation and represents the best evidence to date for proton emission from an oblate nucleus. [Copyright &y& Elsevier]

Excited states in the neutron-deficient odd-odd proton-unbound nuclide 158Ta have been investigated in two separate experiments. In the first experiment, 166Ir nuclei were produced in the reactions of 380 MeV 78Kr ions with an isotopically enriched 92Mo target. The α-decay chain of the 9+ state in 166Ir was analyzed. Fine structure in the α decay of the 9+ state in 162Re established a 66 keV difference in excitation energy between the lowest-lying 9+ and 10+ states in 158Ta. Higher-lying states in 158Ta were populated in the reactions of 255 MeV Ni58 ions with an isotopically enriched 102Pd target. Gamma-ray decay paths that populate, depopulate, and bypass a 19- isomeric state have been identified. The general features of the deduced level scheme are discussed and the prospects for observing proton emission branches from excited states are considered. [ABSTRACT FROM AUTHOR]