Conversion coefficients and band assignments in Ta-180

The conversion coefficients for several bandhead decays in Ta-180 have been measured using pulsed-beam techniques and the Yb-176(Li-7,3n)Ta-180 reaction. The spin and parity of the 520 keV Intrinsic state is established as 4(+) and several earlier assignments are confirmed. Two-quasiparticle configurations for the 520 and 592 keV states are discussed and following reanalysis of the band properties, a consistent interpretation is reached. The 520 keV 4(+) state is associated with the favored coupling of the nu 1/2(-)[521]x pi 9/2(-)[514] configuration while the 592 keV (5(+)) state is identified with the nu 1/2(-)[510]x pi 9/2(-)[514] configuration

The GDR width in the excited 147 Eu compound nucleus at high angular momentum

Abstract High-energy γ -rays emitted in the decay of the hot compound nucleus 147 Eu have been measured in coincidence with low-energy γ -rays. The γ transitions from the different residual nuclei were detected by a multiplicity filter and by Ge detectors. The employed reaction was 37 Cl + 110 Pd at bombarding energies of 160, 165 and 170 MeV. The measured high-energy γ -ray spectra were analysed within the framework of the statistical model using the Cascade code. The GDR width in the angular momentum interval between 35 and 50 ℏ was found to increase weakly and to be rather well predicted by the thermal shape fluctuation model. Also the deformation parameter β as a function of the average angular momentum extracted from the data was found to be in general agreement with the model

Occurrence of a chiral-like pair band and a six-nucleon noncollective oblate isomer in ¹²⁰I

We report for the first time two distinctive features in the odd–odd nucleus 120 I: a pair of doublet bands and a high-spin isomer built on the πh11/2νh11/2 configuration. For producing the excited states of 120 I, a fusion-evaporation reaction 118 Sn( 6 Li, 4n) at E =lab48 MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with Z=53 . The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the πh11/2νh11/2 configuration. In contrast, the high-spin isomer with a half-life of 49(2) ns at spin-parity Jπ=25+ can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the 114 Sn core: three protons (g7/2)1(d5/2)1(h11/2)1 and three neutrons (h11/2)3 . This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of 114 Sn with Z=50 and N=64 .Dr. C. Yuan acknowledges the National Natural Science Foundation of China (11775316

Spherical and deformed isomers in Pb-188

Several isomers in Pb-188 have been identified using pulsed beams, the recoil-shadow technique, and the Er-164(Si-28,4n) Pb-188 reaction. Two of the isomers feed the 10(+) state of the yrast sequence and are suggested to be the 11(-) and 12(+) states from oblate and spherical configurations, respectively. The 12(+) isomer is fed weakly by another isomer with a relatively long lifetime, but it has not been characterized. A fourth isomer with a lifetime of about 1.2 mu s leads via a complicated path to the 8(+) and lower spin yrast states. It is a candidate for the K-pi = 8(-), two-quasineutron state which occurs systematically in N = 106 prolate-deformed nuclei, supporting the assumption that the intruding collective well is prolate

Observation of the 0+ 2 and γ bands in 98Ru, and shape coexistence in the Ru isotopes

Excited states in 98Ru were investigated using γ-ray spectroscopy following the β-decay of 98Rh, and via the 100Ru(p,t) reaction. Combining the results from the two experiments, two states were revised to have spin-parity of 4+ and subsequently assigned to the 02+ and “γ” bands, respectively. The observed structures in 98Ru are suggested to be deformed and rotational, rather than spherical and vibrational, and fit well into the systematics of these excitations in the Ru isotopes. The 02+ excitation is suggested as a shape coexisting configuration. This observation eliminates some of the last remaining candidates for nearly harmonic vibrational nuclei in the Z≈50 region. Beyond-mean-field calculations are presented that support shape coexistence throughout the Ru isotopes with N=52–62, and suggest a smooth evolution of the shape

Possible Conservation of the K -Quantum Number in Excited Rotating Nuclei

The \ensuremath{\gamma} cascades feeding into low-K and high-K bands in ${}^{163}$Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1${0}^{9}$ triple coincidences, \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region 30\ensuremath{\Elzxh}\ensuremath{\le}I\ensuremath{\le}40\ensuremath{\Elzxh} is suggested as explanation

Triaxial Superdeformation in 163 Lu

Abstract High-spin states in 163 Lu have been investigated using the Euroball spectrometer array. The previously known superdeformed band has been extended at low and high energies, and its connection to the normal-deformed states has been established. From its decay the mixing amplitude and interaction strength between superdeformed and normal states are derived. In addition, a new band with a similar dynamic moment of inertia has been found. The experimental results are compared to cranking calculations which suggest that the superdeformed bands in this mass region correspond to shapes with a pronounced triaxiality ( γ ≈±20°)

Competing T = 0 and T = 1 structures in the N = Z nucleus 3162Ga

The low-lying levels in the odd-odd N = Z nucleus 62Ga have been identified for the first time. These data reveal a cascade of stretched-E2 transitions based on a T = 0, 1+ bandhead which decays directly to the T = 1, 0+ ground state. The observed levels are interpreted in the context of theshell model, using as a basis, the pf5/2g9/2 orbits with a 56Ni core